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TRYPANOSOMES AND TRYPANOSOMIASES
TRYPANOSOMES
AND
TRYPANOSOMIASES
BY
A. LAVERAN
Membre de l'Institut, et de l'Acad^mie de M^decine, Paris
AND
F. MESNIL
Chef de Laboratoire A l'Institut Pasteur
TRANSLATED AND MUCH ENLARGED BY
DAVID NABARRO, M.D., B.Sc, D.P.H., Lond.
Member of the Royal College of Physicians, London ; Assistant-Professor of Pathology
AND Bacteriology, University College, London : Scientific Assistant in Pathology
at the University of London ; Royal Society Commissioner for the Study
of Sleeping Sickness in Uganda, 1903
WITH COLOURED PLATE AND EIGHTY-ONE FIGURES IN THE TEXT
./t
CHICAGO
W. T. KEENER & CO.
90 WABASH AVENUE
1907
\ 907
PREFACE TO THE ENGLISH EDITION
Three years have elapsed since the publication of Professors
Laveran and Mesnil's ' Trypanosomes at Trypanosomiases.' When
the work appeared it contained practically all that was known about
the subject at the time ; consequently, it has been an indispensable
book of reference to all subsequent investigators in this particular
branch of pathology. During the past three years a great deal of
work has been done in Europe, Asia, Africa, and America upon the
life-history and development of the trypanosomes, as well as upon
the trypanosome diseases of man and the lower animals. The great
activity in this direction is, no doubt, largely due to the stimulus
given by the discovery (made in 1903) that sleeping sickness is a
stage of human trypanosomiasis — in fact, that it is a human tsetse-
fly disease.
This large output of original work — over 200 new references to
recent papers are given in this edition — has made it necessary to do
more than merely publish a translation of the original book. The
work has been brought thoroughly up to date, considerable additions
being made to practically every chapter. All such additions are
enclosed within square brackets [-], and for the added matter I
alone am responsible. Among the most important additions may be
mentioned : The spirochsetes ; the Leishman-Donovan body ; several
new trypanosomes of small mammals, birds, Batrachians, and fishes ;
recent observations on the occurrence of flagellates in tsetse-flies,
mosquitoes, leeches, etc., and the possible relation of these parasites
to the sexual forms of the trypanosomes of vertebrates ; the recent
observations upon the prevalence of human and animal trypano-
somiases in various parts of Africa and in Asia ; many facts in con-
nection with human trypanosomiasis ; and the microscopic changes
found in the central nervous system in sleeping sickness and in
dourine. A new chapter has been written on the ' Treatment of the
Trypanosomiases.'
The result of incorporating all the latest information has been to
increase the work by more than one half the original size ; but by the
use of a larger page, and the rather free use of closer type for a con-
siderable portion of the added matter, the book contains only 100 pages
more than the original. The labour involved in carrying out the
work has been very great — far greater, indeed, than I anticipated
vi PREFACE
when I began the translation. The excellent abstracts by Mesnil in
the Bulletin de I'Institut Pasteur of practically all papers dealing with
trypanosomes have been of considerable assistance to me, and have
rendered my task somewhat lighter than it would otherwise have
been. I am greatly indebted to Professor Mesnil for permission to
quote from these abstracts, and I have done this in several instances,
due acknowledgment being made in the text.
I wish to acknowledge my indebtedness to many English and
foreign periodicals, more particularly to the various reports of the
Sleeping Sickness Commission of the Royal Society ; the Comptes
Rendus des Seances de I'AcadSmie des Sciences, and of the Societe de
Biologie ; the Annates and the Bulletin de I'Institut Pasteur; the
Journal of Infectious Diseases ; the Thompson Yates and Johnston
Laboratory Reports ; the Lancet and the British Medical Journal ;
the Arheiten aus dem kaiserlichen Gesundheitsamte ; and the Central-
blatt fiir Bakteriologie.
My thanks are due to all who have kindly helped me during the
progress of the work, especially to the authors for sending me copies
of their own papers, as well as of those of their pupils, and for the
interest they have taken throughout ; to Dr. A. C. Stevenson for
drawing many of the new illustrations ; to Professors E. A. Minchin
and F. G. Novy and Drs. Mott and G. Martin for sending me copies
of their publications ; to Professor L. Brandin, Dr. G. C. Chubb,
and Messrs. E. E. Austen and W. G. Hartog for constant help ; and,
lastly, to Mr. Wilfred Trotter and Dr. H. M. Woodcock for much
valuable criticism and help in reading the proofs. My thanks are
also due to the publishers for the patience they have shown during
the delayed production of the work, and for their invariable courtesy.
In conclusion, I can only hope that this ampHfied English edition
may be as favourably received as was the original, and that it may
prove as useful to subsequent investigators ; I shall then not have
laboured in vain.
DAVID NABARRO.
University College, London,
/«//, 1907.
CONTENTS
PAGE
Authors' Introduction -..--.. xv
CHAPTER I.
Historical : Geographical Distribution of the Trypanosomiases - i
CHAPTER II.
Technique for the Study of the Trypanosomes.
Section i. — Examination in the Living State ----- 7
„ 2. — Staining Methods ------- 8
„ 3. — Preservation z'« wVr(7 and Cultivation of Trypanosomes - - 13
„ 4. — Inoculation Experiments -- - - - -15
CHAPTER III.
Comparative Study of the Trypanosomes.
Section i. — General and Comparative Morphology - - - - 16
„ 2. — Biology of the Trypanosomes - - - - - 27
„ 3. — Historical Survey of the Genera of Trypanosomes - -31
„ 4. — Position of the Trypanosomes amongst the Flagellates - - 35
*The Spirochetes ------- 45
*The Leishman-Donovan Body - - - - - 48
„ 5. — Significance of the Basal Corpuscule of Trypanosomes ; its
Centrosomic Nature - - - - - -51
CHAPTER IV.
Trypanosoma lewisi — Parasite Peculiar to Rats.
Section i. — Historical Review and Geographical Distribution - - 58
jj 2.— The Course of Experimental Infection - - - - 61
ij 3. — Study of Trypanosoma lewisi - - ■ - - 68
„ 4. — Agglomeration of Trypanosoma lewisi - - - - 80
,j 5.— Natural Modes of Infection in Rats - - - - 88
^^ 6. — Active Immunity : its Mode of Production - - 90
„ 7.— Passive Immunity: Attempts at Treatment - - - 93
CHAPTER V.
Different Trypanosomes of Small Mammals.
Section i. — *Trypanosome of the Mouse (T. duiioni) ■ - - - 99
2. — Trypanosome of the Bandicoot ( 7". ^a«^2ffi, n. sp.) - - - no
„ II. — *Trypanosome of the Badger ( T'. /^j'^awaz) - - -no
CHAPTER VI.
Nagana and Allied African Diseases.
Historical Review and Geographical Distribution - - - - in
PART I.— NAGANA.
Section i. — Animals Susceptible to Nagana; Refractory Animals ; Symptoms
and Course of the Disease in Different Animals - ■ 121
„ 2. — Pathological Anatomy ------ 14c
♦Changes in the Blood and Internal Organs - - - 143
„ 3. — R^sumd of Symptoms and Pathological Anatomy - - 146
„ 4. — Morphology of Trypanosoma brucei ; Action of Heat and Cold ;
Cultivation Experiments; Agglomeration; Involution Forms - 150
„ 5. — The ^Etiology of Nagana ; the Role of the Tsetse-Fly and of the
Big Game .,-.._- 164
„ 6. — Treatment - - - - - - - -169
„ 7. — Prophylaxis - - _ . . - - - 178
PART 11.— DISEASES ALLIED TO NAGANA.
Section i. — *General Considerations ; Classification of the Trypanosomiases ;
Methods of Differentiation and Identifying the Pathogenic
Trypanosomes - - - - - - - 185
2. — Trypanosomiasis of German East Africa - - - - 190
3. — Trypanosomiasis of Togoland ----- 1^3
4. — *Trypanosomiases of Cameroon ----- jgg
5. — *Trypanosomiasis of Somaliland ----- 201
6. — *Trypanosomiases of Abyssinia and Erythrea - - - 202
7. — *Trypanosomiases of the Anglo-Egyptian Sudan - - 203
8. — *Trypanosomiases of Uganda and Adjacent Parts of East Africa 204
9. — Trypanosomiases other than Dourine, found in Algeria - - 210
10. — Trypanosomiases of the French Sudan - - - . 219
1 1. — *Trypanosomiases of French Guinea - - . . 226
CHAPTER VII.
Trypanosomiasis of Horses in Gambia.
Section i. — *Geographical Distribution ..... 229
„ 2.— The Course of the Disease in Horses .... 230
„ 3. — Course of the Disease in other Animals - - - - 233
„ 4. — Trypanosoma dimorphon ------ 240
„ 5. — Individuality of Trypanosoma dimorphon - - ■ . 243
„ 6. — Mode of Propagation ---._. 244
„ 7. — Treatment -------- 245
CONTENTS IX
CHAPTER VIII.
Surra.
I'AGE
Section I. — Historical: Geographical Distribution of the Disease - - 246
„ 2. — Animals Susceptible to Surra ----- 254
„ 3. — Pathological Anatomy - - - - - - 271
„ 4. — Trypanosoma evansi ...... 272
„ 5. — Surra is a Distinct Disease _ . _ . - 277
„ 6. — Etiology; Mode of Infection . - _ . - 278
„ 7. — Treatment ; Prophylaxis ------ 282
Appendix A. — Lingard's Giant Trypanosome of Cattle - - - 285
„ B. — *Trypanosomiasis of Horses in Annam - - - 286
CHAPTER IX.
Mal de Caderas.
Section l. — Historical ; Geographical Distribution - - - - 292
-Animals Susceptible to Caderas ----- 293
-Pathological Anatomy - - . . 302
-Trypanosoma equinuni ------ 303
-Caderas is a Distinct Disease - - - ' - - 306
-Mode of Propagation ------ 307
-Treatment ; Prophylaxis ------ 308
CHAPTER X.
DOURINE.
Section I. — Historical Survey and Geographical Distribution - - - 312
„ 2. — Dourine in the Equidae .-_--. 314
*Pathological Anatomy ------ 320
,, 3.— Experimental Dourine in Susceptible Animals - - 322
Refractory Animals - - - - - - 331
„ 4. — Trypanosoma equiperdum ------ 332
„ 5. — The IndividuaUty of Dourine ----- 335
„ 6. — Mode of Propagation ------ 337
„ 7. — Treatment ; Immunity ; Prophylaxis - - - - 338
Appendix. — ' Maladie de Soemedang,' Java ----- 341
CHAPTER XI.
Galziekte (Gall-Sickness).
Section i. — Historical ; Geographical Distribution - - - . 343
„ 2. — Gall-sickness is a Disease Peculiar to the Bovidas - - 345
„ 3. — Course of the Disease; Symptoms . - - . 346
„ 4. — Pathological Anatomy ------ 347
„ 5. — The Pathogenic Agent ------ 347
„ 6. — Mode of Propagation - - - - - - 35°
„ 7. — Treatment; Prophylaxis - - - - - - 351
CHAPTER XII.
Human Trypanosomiasis, including, Sleeping Sickness.
Section i. — Historical -------- 352
„ 2. — Geographical Distribution - - - . - 35^
X CONTENTS
PAGE
Section 3.— Predisposing Causes ; The Influence of Age, Sex, Occupation,
Race, etc. .--...- 366
„ 4. — Description of the Disease - - - - ■ 3°9
,, 5. — The Pathogenicity of Trypanosoma gambiense for Different
Animals - - - - - - - 3°2
,, 6. — Pathological Anatomy - - - - • - 39i
*The Changes in the Brain and other Organs in Sleeping
Sickness -------- 393
7. — The Pathogenic Agent : Trypanosoma gambiense - - 39^
8.— Mode of Propagation ------ 406
,, 9. — Diagnosis -------- 409
,, 10. — Prognosis -------- 410
,, II. — Treatment; Prophylaxis - - - - - 411
CHAPTER XIII..
*The Treatment of the Trypanosomiases.
Section i. — *Historical Review of the Treatment of the Trypanosomiases in
General - - - - - - - - 41 5
,, 2. — *Experiments on Treatment with Agents other than Chemical
Substances : Serums and Spleen Extracts ; Cultures of
Organisms; X Rays and other Rays; Light - - - 417
,, 3. — *Recent Experiments on Treatment with Arsenic Compounds,
including Atoxyl, and with Trypanred - - - - 420
,, 4. — *Treatment by Means of Benzidine Dyes - - - - 426
,, 5. — *Treatment of Human Trypanosomiasis and of Experimental
Infections with Trypanosoma gambiense in Animals ■ - 433
CHAPTER XIV.
Trypanosomes of Birds.
Section i. — Historical Review and Geographical Distribution - • 439
„ 2. — Morphology and Cultivation of the Trypanosomes of Birds - 443
*Novy and McNeal's Observations on the Trypanosomes of Birds 45 1
CHAPTER XV.
Trypanosomes of Reptiles.
Trypanosoma damomce oi the TortOKQ - ----- 4-7
* Trypanoso>na boueii of the Lhard ...... ^^g
CHAPTER XVI.
Trypanosomes of Batrachians.
Section i. — Historical and Geographical Distribution - - - . 460
„ 2. — Trypanosoma rotatorium - - - - - - 465
* Trypanosoma borreli .--..- ^gg
*Cultivation of Trypanosoma rotatorium - - - - 470
„ 3. — Trypanosoma inopinatuin - - - • _ . . ^7^
*Development of Frog Trypanosomes in Leeches - - 474
„ 4- — *Other Trypanosomes of Batrachians - - - - 475
*Trypanosoma nelspruitense of Frogs in the Transvaal - - 475
♦TVy/a^ojowza fe//z, n. sp. of Frogs in Hong-Kong - - 476
*Trypanosoma somalense oiX\ie'S,fyca.2X'\axi6,'YQ2LA - - 477
*Trypanosome of the Newt . . . - . 477
„ 5. — Modes of Infection ------- 478
CONTENTS xi
CHAPTER XVII.
Trypanosomes of Fishes.
PAGE
Section I. — Historical; Species known to be Infected - ... 479
„ 2. — Technique ; Preservation of the Trypanosomes of Fishes - 484
„ 3. — Description of the Trypanosomes of Fishes belonging to the
Genus Trypanosoma - ■ - - - - 4S5
*The recently described Species of this Genus • - - 493
„ 4.- — ^Description of the Trypanosomes of Fishes belonging to the
Genus Trypanoplasma ------ 496
*Recent Observations on the Trypanoplasms of Fishes - - 501
„ 5. — Mode of Multiplication of the Trypanosomes of Fishes - - 502
„ 6. — Modes of Infection ...... 502
*Development of Trypanosomes and Trypanoplasms in Leeches 504
CHAPTER XVIII.
The Tsetse-Flies and their Trypanosomes.
Part i.—*The Trypanosomes of Tsetse-Flies ----- 508
,, 2. — The Tsetse-Flies - - - - - - jn
Index ---------- 522
TABLES.
1. Table showing the Results obtained in Various Animals infected with
Nagana by Different Investigators - - . - - 124
2. Table showing the Results obtained by Schilling and by Martini with the
Togo Virus . - . . . . - 197
3. Table giving the Dimensions of the Bird Trypanosomes - - - 447
4. Dichotomous Table of the Species of the Genus G/ojjz^a - - - 521
MAPS.
1. Map showing the Geographical Distribution of the Animal Trypano-
somiases ---.-.-. 4
2. Map showing the Distribution of Surra in India and Indo-China - - 250
3. Map of Equatorial Africa, showing the Distribution of Human Trypano-
somiasis .----.-. 260
LIST OF ILLUSTRATIONS
1. Map showing the Geographical Distribution of the Animal Trypano-
somiases ..---..- 4
2. Trypanosomes of Mammals and Batrachia — Trichomonas - - i7
3. Trypanosomes of Fishes - - - - - - - 18
4. Flagellates. Spermatozoa. Flagellated Spore oi Noctiluca - - 39
5. Transformation of an Ookinete of an Intracorpuscular Parasite into a
Trypanosome --------42
6. Transition of Trypanosomes into Spirochaetes - - - - 43
*7. Treponema pallidum and various Spirochaetes - - - - 46
*8. The Development of the Leishman Bodies in Cultures - - - 49
*9. Stages in the Development of the Flagellum in Cultures of the Leishman
Body --------- 50
10. Multiplication Forms of 7Vj7iaK<7j'<7;«a /^a//jz - - - - 71
11. Trypanosoma lewisi \X). \!s\^ G\i\-a&s,-^\g. Involution Forms - - 73
12. Culture Forms of Trypanoso?na lewisi - - - - - 79
13. Agglutination Forms of Trypa/iosoma lewisi - - - - 83
*I4. Sexual and Conjugation Forms of Trypanosoma lewisi - - - 89
15. Engulfment of a Trypanosome by a Leucocyte - - - - 92
16. Trypanosomes of Mus rattus, of the Rabbit (Petrie), and of the Indian
Squirrel (Donovan) ------- 103
*I7. Trypanosomes of the Mole {T. talpa) and Bat [T. vespertilionis) - 109
18. Temperature Charts of Three Dogs with Nagana - - - 127
19. Temperature Charts of a Donkey and Horse with Nagana - -133
20. A Horse suffering from Nagana - - - - - -134
21. Chart showing the Temperature and Number of Parasites in a Cow with
Nagana - - - - - - - -137
22. yivX'CvpXxcz.'Cxon. oi Trypanosoina brucei - - - - - I53
*23. Details in the Division of Nucleus and Ceutrosome oi Trypanosoma irucei 155
24. Involution and Agglomeration Forms of Trypanosoma brucei - - 163
25. Temperature Charts of Two Horses suffering from the Gambian Try-
panosomiasis -------- 232
26. Temperature Chart of a Dog infected with Trypanosoma dimorphon - 237
27. Temperature Chart of a Goat infected with Trypanoso?na dirnorphon - 239
28. Trypanosoma dimorphon ------- 242
29. Map showing the Distribution of Surra in India and Indo-China - 250
30. 31. Temperature Charts of Horses suffering from Surra - - 254, 256
32. Temperature Chart of a Calf infected with Surra- - - - 260
33, 34. Temperature Charts of Two Dogs infected with Surra - 262, 263
35. Temperature Chart of a Sheep infected with Surra - - - 270
36. Trypanosomes of Surra, of Nagana, and of Caderas - - - 273
*37. Culture forms of the Philippine Surra Trypanosome - - - 275
38. The Giant Trypanosome of Lingard ----- 286
39. Temperature Chart of a Horse with Caderas - - - . 294
40. Temperature Chart of a Dog with Caderas - - . . 298
* The figures marked with an asterisk have been added, and are not given in the
original.
xiii
xiv LIST OF ILLUSTRATIONS
FIG. PAGE
41. Trypanosome of Caderas ------- 304
42 Photograph of a Horse with Dourine - - - - - 3^5
43. Temperature Charts of a Horse and Donkey with Dourine - - 3^7
44. Trypanosoma equiperdtim ....-- 333
45. Trypanosoma theileri axidi Trypanosoma transvaaliense - - - 347
46. Hippobosca rufipes -------- 350
47. Map of Equatorial Africa showing the Distribution of Human Trypano-
somiasis -------- 360
48. Temperature Chart of a Patient in the Early Stage of Human Trypano-
somiasis - - - - - - - -371
49. Temperature Chart of a Sleeping Sickness Patient - - - 373
*5o. Photograph of an Advanced Case of Sleeping Sickness in a Native of
Uganda - - - - - - - - - 374
*5i. Photograph of a Persian suffering from Sleeping Sickness - - 375
52. Temperature Chart of a Dog inoculated with 7'ry;)rt«oj'(5;»a^awz&>;2.fe - 386
*53> 54i 55- Changes seen in the Brain in Sleeping Sickness - - 394, 395
*56. Section of a Vessel in a very Chronic Case of Sleeping Sickness, showing
Marked Perivascular Infiltration ----- 396
57. Trypanosoma gambiense ----- - - 402
*58. Sexual and Indifferent Forms of Trypanosojna gambiense - - 403
59. Trypanosomes of Birds (after Danilewsky) - - - ' ■ 443
60. Trypanosoma avt'utn oi the Owl - - - - - - 445
6r. Trypanosomes of Different Birds ------ 446
62. Trypanosom,a damonicE - - - - - - - 458
63. Trypanosoma rotatorium of Rana esculenta - - - - 467
64. Trypanosoma mega and Trypayiosoma karyozeukton - - - 468
65. Trypanosome of Hyla arborea . . . . . 46g
*56. Culture forms of Trypanosoma rotatorium - - - - 472
67. Trypanosoma inopinatum ------- 474
*68. Trypanosoma belli from a Frog in Hong-Kong - - - 476
69. Trypanosoma remaki of the Pike ------ 485
70. Stages in the Multiplication of Trypanosoma remaki - - - 487
71. Trypanosomes of the Carp and Tench ■ - ■ - - - 488
72. Trypanosomes of the Sole and Eel - - - • -491
73. Trypanosomes of the Dogfish and Ray ----- 492
74. Trypanoplasma borreli ------- 4^7
*75. Trypanosomes of the Tsetse-Fly (7!, _^rayz') . - _ . 509
*76. Trypanosomes of the Tsetse-Fly (T". /«//(7f;^z') - - - - 510
77. Glossina morsitans - - - - - - "512
78. Glossina morsitans, 'Reiore and loiter Yeed\n% - - - "5^3
79. Pupa of the Zululand Tsetse-Fly - - - - - -515
80. External Mouth Parts and Pharynx of G^/oMz?za ;«o^«'/a«j' - - 517
81. Glossina palpalis - - - - - - - '517
Coloured Plate at End of Volume.
AUTHORS' INTRODUCTION
In 1892 one of us was able within the compass of a short article
in a medical journal^ to give a resume of our knowledge of the
Trypanosomes. To-day it requires a whole volume to relate all
that is known about these hsematozoa and the diseases to which
they give rise.
The subject of the Trypanosomes and the Trypanosomiases has
grown very considerably during the past twelve years. In 1892
the existence of trypanosomes had been demonstrated in several
of the lower animals, but the morphology of the parasites was little
known, and only one pathogenic species had been described — namely,
that which produces, especially in the Equidse, the disease known as
surra in India.
In recent years numerous investigators have devoted themselves
to the study of the trypanosomes. Methods of staining, preserving,
cultivating, and inoculating the parasites into a number of different
animal species have made immense progress ; questions of mor-
phology have been elucidated ; and, finally, successive discoveries
of the greatest interest and importance have shown that trypanosomes
play, in veterinary and in human pathology, a part the importance
of which was hitherto unsuspected.
In addition to surra, it has been found necessary to include
successively amongst the animal trypanosomiases the following
diseases : nagana, or tsetse-fly disease ; mal de caderas ; dourine ;
galziekte (gall-sickness) ; a disease amongst horses in the Gambia
Colony ; and several other African trypanosome affections, of which
the study is still incomplete. The importance of surra itself has
increased, on account of serious epidemics of the disease in
Mauritius, Java, and the Philippines outside its endemic area.
The discovery of a human trypanosomiasis in Africa — a
trypanosomiasis to which must undoubtedly be attributed the
symptoms known for more than a century under the name of
sleeping sickness — has shown that trypanosomes must henceforth
take their place amongst the pathogenic agencies, whose study is
as indispensable to the physician as to the veterinary surgeon.
In 1892 trypanosomes had little interest for practitioners outside
certain regions of India where surra was prevalent. This is no
^ A. Laveran, Arch. mid. expMm., March i, 1892.
xvi AUTHORS' INTRODUCTION
longer the case. It can now be said that trypanosomiases are
amongst the most widely distributed of diseases. The importance of
the trypanosomiases cannot be too much impressed upon vetennary
surgeons. All practitioners, as well as all veterinary surgeons, may
be called upon to diagnose cases of trypanosomiases, even away
from their endemic areas.
The extension of the colonial empires of European nations m
Africa, the means of rapid transport, and the growing facilities for
ocean travel, will undoubtedly favour the spread of human trypanoso-
miasis, of which a certain number of cases have already been observed
among Europeans.
On the Congo and in Uganda the invincible progress of sleeping
sickness has been evident for several years.
As to the animal trypanosomiases, the danger of their spread
from the endemic areas is proved by a number of facts. This
danger is increased by the development of commercial intercourse
and the transportation of animals by sea, and also by the fact that
the trypanosomiases of cattle and horses often run a slow and
insidious course.
The serious outbreak of surra which has recently afflicted
Mauritius is a notable instance of the ravages which certain trypano-
somiases can cause, when prompt and energetic measures are not
taken to prevent their spread.
In two years (1902-1903) the people of Mauritius lost nearly all
their draught animals (horses and mules) and a large number of their
cattle. The nature of the disease having been unrecognised at the
outset, it is easy to see how the animals, scattered over the whole
island, rapidly caused the spread of the infection. In Java more
energetic prophylactic measures succeeded in limiting the extent
of a similar outbreak. [Animal trypanosomiases also occur in the
Philippines, and quite recently have been recognised in Hong Kong.]
So far as the French possessions are concerned, these diseases have
been already noted in Algeria, Tonkin, Cochin China, French Guinea,
and the Sudan. Moreover, the fact cannot be ignored that Reunion
and Madagascar are seriously threatened.
[Most of the British possessions in Africa, as well as India and
Burmah, are similarly smitten by these animal trypanosomiases —
parts of Cape Colony, Natal, Orange River Colony, and Transvaal ;
British Central Africa, Uganda, and the East African Protectorates ;
the River Gambia Colony, Sierra Leone, and Nigeria.]
For several years we have been studying the trypanosomes.
It appeared to us that the time had come to collect and to condense
the numerous publications on the subject, in order to lessen the
labour of investigators, who must find it increasingly difficult to
procure the monographs written in all languages, or the articles
scattered throughout a large number of journals. Moreover, it is
AUTHORS' INTRODUCTION xvii
impossible to get these references in the small stations in our
colonies, where the study of the human and animal trypanosomiases
is so essential at the present day.
It might have been wiser perhaps to wait some years before
writing this book. Our knowledge of the trypanosomes is still
incomplete, and we are justified in believing that the rich harvest
of discoveries concerning these hsematozoa made during the last few
years is not nearly completed. Science, especially natural and
medical science, is always undergoing evolution, and one can never
hope to have said the last word upon any branch of it. The only
aim in writing a book such as this, is to gather together facts known
at the present time about a special subject, and to facilitate the
study of that subject by future investigators.
We have been particularly fortunate during our researches upon
the trypanosomes. We have succeeded in getting together at the
Pasteur Institute in Paris an almost complete collection of try-
panosomes, and we have been able to study them, not only in
stained preparations, but also in the living state, which has enabled
us to follow the evolution of the trypanosomiases in a large number
of species of lower animals, to compare the trypanosomes in them,
and to differentiate several species which had hitherto been confused.
The trypanosome of the rat, which is found almost everywhere, is an
excellent one to study. We used it in our earliest researches upon
the morphology and biology of trypanosomes. We have succeeded
in procuring successively the trypanosomes of nagana, dourine,
surra, mal de caderas, a disease amongst horses in the Gambia
Colony, mbori, and human trypanosomiasis of the Gambia Colony
and Uganda.
Further, we have been able to study the trypanosomes of birds,
Batrachia, Chelonia, and fishes. We have described several new
species of trypanosomes, notably amongst salt-water fishes, and we
have found a trypanosome in a fresh-water fish — the red-eye — which
has enabled us to establish the existence of a new genus, the genus
Trypanoplasma .
The study of the trypanosomes, or at least of some of them,
presents considerable difficulties. Several mammalian trypanosomes
resemble one another so closely that it is impossible to distinguish
them by their morphological characters alone. This applies to
the trypanosomes of nagana, surra, dourine, and sleeping sick-
ness. Moreover, trypanosomes belonging to distinct species may
present close analogies from the point of view of their pathogenic
action on certain animals. On the other hand, the virulence of a
trypanosome is influenced by various factors. It varies specially
with the origin and race of the animals inoculated. A trypanosome
only slightly virulent for a species of animal from the Sudan, for
example, may be very virulent for the corresponding European
species. Also the same trypanosome may present slightly different
xviii AUTHORS' INTRODUCTION
morphological characters in the blood of different species of animals.
It follows, therefore, that it may often be difficult to identify a
trypanosome, and on that account several of these hsematozoa still
lack identification.
Some observers have maintained that the names surra and nagana
referred to the same disease, while others have sought to identify
mal de caderas with surra. On the other hand, it was believed for
some time that the trypanosome found in the blood of man in
Gambia was different from that found in Uganda in the cerebro-
spinal fluid of sleeping sickness patients. At the present day there is
a little uncertainty about the nature of several African trypanosomes
— notably that of the epizootic disease amongst dromedaries in Tim-
buctoo, which has been described under the name vibori}
To identify a trypanosomiasis one must take into consideration :
(i) the morphological and biological characters of the trypanosomes ;
(2) the symptoms of the disease as it occurs naturally ; (3) the
pathogenic action on different mammals ; and (4) the action of
the particular trypanosome upon animals immune against allied
species of trypanosome. In this way we have succeeded in showing
that nagana, surra, and mal de caderas are three distinct morbid
entities ; that the trypanosomiasis of horses in Gambia has nothing
in common with the human disease ; and, lastly, that the Trypano-
soma gambiense and Trypanosoma tigandense should be regarded as
identical.
Nocard and Lignieres have shown in the same way that dourine'
is distinct from nagana and from mal de caderas.
In certain trypanosomiases and amongst certain species of
animals the parasites are very scanty in the blood and body fluids,
a fact which greatly increases the difficulties of investigation. In
animals with dourine it is rare to find trypanosomes in the blood,
whereas they are met with in large numbers in the oedema fluids.
In sleeping sickness it is often necessary, in order to demonstrate
the presence of trypanosomes, to centrifuge the blood or the cerebro-
spinal fluid obtained by lumbar puncture.
The paucity of the parasites in the blood does not preclude their
pathogenic action. In addition to dourine and human trypano-
somiasis, animals may succumb to other trypanosomiases even when
the parasites are very scanty in their blood. In this respect there
are great differences amongst mammals. The trypanosomes of surra,
nagana, and mal de caderas swarm in the blood of infected rats,
mice, and dogs, whilst they are scanty, or very scanty, in the blood of
infected rabbits, goats, sheep, and cattle. Although the trypanosomes
appear to multiply with difficulty in these animals, the infection is
none the less serious. Surra, nagana, and mal de caderas always
cause death in rabbits.
^ [It has recently been shown by Laveran that mbori is merely a variety of
surra. See Chapter VI.]
AUTHORS' INTRODUCTION xix
We know how the majority of the trypanosomiases are spread.
Tsetse-flies convey nagana and human trypanosomiasis. Other
biting flies convey surra and gall-sickness, whilst dourine is trans-
mitted by coitus.
Prophylactic measures based on these setiological data can render,
and already have rendered, great service.
Our knowledge as to the treatment of trypanosome diseases is
less advanced. It is especially to that aspect of the subject that
future investigators should direct their efforts and attention.
Professors Nocard and Valine have been good enough to com-
municate to us the results of experiments upon the different trypano-
somiases carried out at the Veterinary College at Alfort, parallel
with those which we carried out at the Pasteur Institute, and with
the same parasites. These communications have been a great help
to us. We should much have liked to express our sincere thanks to
Nocard, but unfortunately we can only deplore the untimely death
of this indefatigable worker — our devoted friend.
Professor Valine is kindly continuing the valuable co-operation
whiph we have been accustomed to find in the college at Alfort. We
ask him to accept our best thanks.
Paris, /une i, 1904.
TRYPANOSOMES
AND THE TRYPANOSOMIASES
CHAPTER I
HISTORICAL— GEOGRAPHICAL DISTRIBUTION OF
THE TRYPANOSOMIASES
Under the general name Trypanosomes are included organisms
belonging to the class Flagellata, of the phylum Protozoa, charac-
terized by the possession of a fusiform body, more or less elongated ;
with, at its anterior extremity, a flagellum, which is continued along
the body of the parasite as the thickened edge of an undulating
membrane. In some cases there is a flagellum at both ends. All
the known species of typical trypanosomes have their normal habitat
in the blood of vertebrates.
We shall designate under the name of the Trypanosomiases'^ those
human and animal diseases produced by certain of these trypano-
somes. Everyone agrees in ascribing to Valentin of Berne the
discovery of the first trypanosome, observed by him in the blood of
the trout {Salmo fario) in 1841. In 1842 and 1843 appeared papers
by Gluge of Brussels, Mayer of Bonn, and Gruby of Paris, upon the
trypanosome of frogs. It was for these parasites of the frog that
Gruby introduced the name Trypanosoma (from Tpviravov, trupanon,
a wimble or borer; and aw/xa, soma, body).
Between 1843 and 1880 our knowledge of the trypanosomes
made but little progress. They were rediscovered and studied anew
at varying intervals in the blood of Batrachia (Wedl, 1850 ; Chaussat,
1850 ; Ray Lankester, 1871 ; Rattig, 1875) and of various fishes
(Remak, 1842 ; Gros, 1845 ; Berg, 1845 ; Chaussat, 1850). It is
possible that Gros and Wedl had seen them in birds, but this is
doubtful. Gros, in 1845, found trypanosomes in the blood of the
field-mouse and mole; Chaussat, in 1850, found them in the black
rat. But attention was only effectually drawn to the trypanosomes
of mammals by the work of Lewis (1878) on the parasites of the
^ [Brumpt has suggested the name ' trypanosomosis ' for the disease due to a
trypanosome, which agrees with the nomencldture of other protozoan diseases — ■
e.^., piroplasmosis, coccidiosis, etc.]
I
2 TRYPANOSOMES AND THE TRYPANOSOMIASES
blood of rats in India. The reason is that Lewis's discovery preceded
by a short time that of the first truly pathogenic trypanosome.
It is a fact which at first sight may seem remarkable that the first
pathogenic trypanosome was only discovered in 1880, forty years after
Valentin's discovery. But one must remember that trypanosome
diseases are essentially tropical in distribution, and that the study of
them was taken up only during the last quarter of the last century.
From 1880, the date of the discovery by Evans ^ of the trypanosome
of surra amongst horses and camels in India, down to 1894, the
date of the discovery by Bruce of the trypanosome of nagana amongst
horses and cattle in Zululand, apart from some experiments upon
the artificial reproduction of surra, investigations were confined to
the non-pathogenic trypanosomes.
Our knowledge of these different parasites was enriched by the
researches of Lewis (1884), Crookshank (1886), Danilewsky and
Chalachnikov (1888), upon the trypanosomes of rats ; of Danilewsky
(1888) on those of birds ; of Danilewsky (1885), Chalachnikov,
Mitrophanov (1883), on those of Batrachia and fishes. The most
important amongst those researches are certainly those of Danilewsky,
who studied at the same time the intracorpuscular hsematozoa of
reptiles, and especially those of birds, which are so closely allied to
that other pathogenic Protozoon, the malarial parasite. But the
knowledge of the trypanosomes acquired was limited to the different
aspects of the parasite in the living state, and, in the case of some of
them, to certain details concerning their mode of equal or unequal
longitudinal division.
A resume of the state of our knowledge towards the end of
that period will be found in an article written by one of us in
March, 1892,^ with the object of bringing into prominence the
interest of those researches upon the trypanosomes. In the writer's
opinion, these researches ought to be undertaken side by side with
those of the endoglobular hasmatozoa of the type of the hasmato-
zoon of malaria.
During the last twelve years our knowledge of the trypanosomes
has increased by leaps and bounds. Two notable investigations
should be mentioned as the starting-point of this forward movement :
First, the remarkable paper by Bruce upon nagana in Zululand,
which appeared in extenso in 1897, and proved conclusively the
role played by a trypanosome in this disease, and at the same
time cleared up the aetiology (the role of the tsetse-flies ; the big
game as reservoirs of the virus). Moreover, it was through Bruce
that the first pathogenic trypanosome was introduced into the
laboratories of Europe, where it has given rise to innumerable
investigations which have materially increased our knowledge.
^ It is interesting to note that the publication of this discovery, made on
December 3, 1880, followed by about a week that of the malarial parasite
(November 23, 1880).
^ A. Laveran, ArcA. mid. exper., March i, 1892.
HISTORICAL 3
Next should be mentioned the work of Rabinowitsch and
Kempner, published in i8gg, on the trypanosome of rats. Here for
the first time the cytological study of a trypanosome was made.
These authors showed that satisfactory results are obtained only by
employing those methods which had just been shown to succeed
so well with the intracorpuscular heematozoa — namely, a suitably
combined mixture of eosin and methylene blue.'^ It is true Rabi-
nowitsch and Kempner from their earlier work did not arrive at
unassailable conclusions ; and the researches carried out in 1900,
first by Wasielewski and Senn and later by ourselves, have intro-
duced corrections into the morphological work of Rabinowitsch and
Kempner. But to these investigators undoubtedly must be given
the credit of having inaugurated the cytological study of the
trypanosomes.
We believe we were the first to give a precise cytological account
of the pathogenic trypanosomes, and to describe in detail their mode
of longitudinal division into equal parts, with figures illustrating
these changes. Our results have all been confirmed and extended
by our own further researches and by the work of others on the
pathogenic trypanosomes, as well as upon the non-pathogenic
trypanosomes of the Batrachia, fishes, reptiles, and birds. During
the progress of our researches we discovered in the blood of a fresh-
water fish — the rudd or red-eye — a trypanosome having, amongst
other peculiarities, a flagellum at each extremity of its body. In
Chapter III. we shall dwell more fully upon its morphological
interest. We may add that closely-allied organisms have recently
been found in the blood of the carp and minnow,^ and that they
appear to be pathogenic for these fishes. Finally, in connection
with the trypanosomes themselves, we have the interesting discovery
made in 1903 by Novy and McNeal, who obtained pure cultures in
a blood-agar medium, first of the rat trypanosome and later of the
nagana parasite.
But it is especially in the discovery of the trypanosome diseases
in man and the lower animals that the last decade was so prolific.
We shall enumerate in the chronological order of the discovery of
their causal agent all the trypanosomiases known at present, with a
general survey of their geographical distribution (for the Animal
Trypanosomiases, see Fig. i).
Surra, the trypanosome of which was discovered in 1880 by Evans,
is very prevalent among the Equidai and Camelidse of the provinces
of Northern India, Bombay, Burmah, Southern China, and various
parts of French Indo-China. It has also been described in Sumatra,
Java, and the Philippines. [Trypanosomiases identical with, or closely
allied to, surra have been found to occur in various parts of Africa.]
' Ziemann, since 1898, had thus stained the two chromatic masses in the
trypanosome of the frog.
^ [In Chapter XVII. will be found the names of other fishes in which similar
parasites occur.]
I — 2
4 TRYPANOSOMES AND THE TRYPANOSOMIASES
In India cattle are but slightly affected. On the other hand,
during the past four years surra has caused a heavy mortality
amongst the cattle in Central Java, and for three years amongst
those in Mauritius.
Nagana, or a disease closely resembling it, appears to be associated
with the presence of one or more species of tsetse-fly. Since Bruce's
discovery the trypanosome has been found in many parts of Africa
GEOGRAPHICAL DISTRIBUTION 5
where fly diseases are prevalent : in Northern Transvaal ; amongst
cattle in German East Africa; cattle and horses in British East
Africa ; dromedaries in Ogaden ; cattle, sheep, and donkeys in the
Belgian Congo territory ; various mammals in the Cameroons ;
horses and cattle in Togoland ; horses in Nigeria, French Guinea,
and the valley of the River Shari ; and amongst the dromedaries and
cattle in Timbuctoo.
Perhaps there are several distinct diseases in the areas just
enumerated.
In the Gambia Colony there is also a trypanosome disease
-affecting horses, discovered in 1903 by Dutton and Todd, which is
undoubtedly distinct from the nagana of Zululand.
In 1894 Rouget found a trypanosome in the blood of a horse
suffering from dourine in Constantine, in Algeria. This discovery
was confirmed in 1899 by Schneider and Buffard, who proved con-
clusively the causal relation of the trypanosome to the disease.
This trypanosomiasis, known also by the name of mal du co'it (for so
far as is known it is conveyed only by coitus), attacks only stallions
and brood mares. It occurs along the African and Asiatic shores
of the Mediterranean, in Persia, and in Turkey ;i cases are still
occasionally met with in Hungary and the North of Spain. It
occurs also in the United States, in the region of the Illinois, and
possibly, too, in Java.
In Algeria dourine is apparently not the only trypanosome
disease which attacks animals. Quite recently trypanosomiases
amongst horses and dromedaries have been described, differing from
dourine both in their mode of propagation, which is not by coitus,
and by the characters of their respective trypanosomes.
In 1901 Elmassian, director of the Bacteriological Institute at
Asuncion, Paraguay, discovered a trypanosome in the blood of
horses with mal de caderas (disease of the hind-quarters). This
disease is prevalent over the whole of the Gran Chaco, the hunting
and cattle-rearing district, and over the adjacent parts of the
Argentine, Uruguay, Paraguay, and Bolivia. Mal de caderas has
also been recognised further north, in the Brazilian province of
Matto-Grosso.
In 1902 Theiler discovered in the Transvaal a disease peculiar to
cattle — galziekte, or gall-sickness, due to a trypanosome which Bruce
and Laveran have described, at the same time drawing attention to
its unusually large size. [This disease has since been described in
other parts of Africa and in Transcaucasia.]
Until 1900) it was thought that the trypanosome diseases were
confined to the lower animals, and that man was immune. In
support of this hypothesis, nagana and other allied fly diseases of
horses and cattle were frequently cited as having never attacked
man, although he had often been bitten by the fly.
1 [Dourine occurs also in India, where it has recently been studied by Lingard
and others. (See Chapter X.)]
6 TRYPANOSOMES AND THE TRYPANOSOMIASES
The researches of the past five years have clearly shown the part
played by trypanosomes in human pathology. Towards the end
of igoi Button discovered a new trypanosome in the blood of a
European resident in the Gambia Colony who was suffering from
irregular pyrexia and enlarged spleen.^ This discovery of a trypano-
some pathogenic for man was soon confirmed in the Gambia Colony
by Button and Todd, and elsewhere (Congo, Uganda) by others.
In May, 1903 was published the important discovery by Castel-
lani in Uganda of a trypanosome in the cerebro-spinal fluid of
negroes suffering from sleeping sickness. This discovery was
speedily confirmed by Bruce and Nabarro, who clearly demonstrated
the intimate association between this trypanosome and sleeping
sickness. It has been recognised, moreover, that this trj'panosome
is identical with that discovered in 1901 by Button [and Forde].
Sleeping sickness is merely the final stage of a blood infection with
trypanosomes.
This human trypanosome is conveyed by a particular species
of tsetse-fly. Human trypanosomiasis has the same geographical
distribution as sleeping sickness — the valleys of West Africa from
the Senegal down to St. Paul de Loanda, and the northern shores of
the Victoria Nyanza. (See special map. Chapter XII.)
This rapid resume shows clearly the importance of the trypano-
some diseases. Their elucidation is, therefore, one of the important
problems of colonial expansion. The experimental study of the
various trypanosomiases has already led to very important results,
which will be found in detail in this book.
Unfortunately, we have progressed very little so far as prevention
and treatment are concerned. It is not possible to inoculate
against these diseases. Graduated treatment with arsenic leads to
an improvement in the condition of animals or human beings
suffering from trypanosomiasis, but a cure has never been effected.
' Trypanrot ' of Ehrlich and Shiga has hitherto cured only mice
inoculated with the trypanosome of mal de caderas. Serum-therapy
has furnished a result interesting from a theoretical point of view,
but not of practical value- — namely, the action of human serum upon
the animal trypanosomes.
[Buring the past few years some progress has been made in the
preventive inoculation of animals, and the recent investigations of
Laveran upon the action of arsenic and trypanred combined, of
Mesnil and Nicolle and of Thomas upon the action of various dyes
and of an arsenic compound (atoxyl), mark a distinct advance
in the prevention and treatment of the trypanosomiases. (See
Chapter XIII. on 'Treatment.').]
1 [It would seem that Forde first discovered the parasite in blood-films but
that Dutton recognised its character. (See chapter on Human Trypanosomiasis.)]
CHAPTER II
TECHNIQUE FOR THE STUDY OF THE
TRYPANOSOMES
Section 1. — Examination in the Living- State.
To study the trypanosomes in fresh blood, a drop of blood from an
infected animal is necessary. In the case of a mammal this is
obtained from a prick or small incision in the ear, or, in the case of
rats and mice, from the end of the tail. In birds prick one of the
big veins on the internal surface of the wing ; in the case of reptiles
take the blood from the extremity of the tail or from a digit ; in
Batrachia cut a digit of one of the limbs, preferably the thumb of an
anterior limb ; finally, in fishes cut one or two rays of the catidal
fin, or make a small cut in the gills.
The drop of blood is taken on a slide and covered with a cover-
slip. To study the structure of the parasites the blood should be
in a thin layer,- otherwise the trypanosomes may be entirely hidden
by the red corpuscles. The movement which the trypanosomes
impart to the red corpuscles enables one to recognise the presence
of the parasites with very slight magnification (loo diameters) when
they are numerous in the blood, and it facilitates finding them, with
greater magnification (300 or 400 diameters), when they are scanty.
In the latter case, if one wishes merely to ascertain the presence of
the parasite in the blood, it is better to take a relatively thick film
of blood, so that the corpuscles form an apparently uniform layer
by being pressed one against the other. With a little practice the
presence of trypanosomes can be recognised by the rotary move-
ments imparted to the adjacent corpuscles. In this way one has the
advantage of examining a relatively big drop of blood.
In doubtful cases, especially if a microbiological diagnosis of
a trypanosome is required, it may often be necessary to examine
successively several blood preparations, and even to repeat the
observation several days afterwards, so long as the examination
is negative {e.g., in the case of ruminants suffering from nagana
or surra; men and various mammals infected with the human
trypanosome).
To facilitate the finding of trypanosomes in the blood, Kanthack,
Durham, and Blandford advised centrifuging the blood rendered
7
8 TRYPANOSOMES AND THE TRYPANOSOMIASES
uncoagulable (as by the addition of sodium citrate solution). The
trypanosomes are found in the middle or leucocytic layer. ^
In the case of dourine, we shall see that it is the blood-stained
oedema fluid which should be examined. In sleeping sickness the
blood and the cerebro-spinal fluid obtained by lumbar puncture
should be examined for trypanosomes after centrifuging.
When it is desired to watch the parasites for a considerable
time, it is necessary to make hanging-drop preparations ringed with
vaseline or paraffin. Such preparations are very useful, especially for
studying the phenomena of agglutination. The blood is diluted with
physiological salt solution and then defibrinated, or with citrated salt
solution to prevent coagulation, or with serum from another animal.
Francis," for Trypanosoma lewisi, advises letting the blood coagulate :
the trypanosomes pass out into the serum, where they can be
studied apart from the red corpuscles. Generally at the end of an
hour in an ordinary slide and coverslip preparation, or a little longer
in the case of a hanging drop, the trypanosomes become less active,
and one is then able to study their shape and the movements of their
various parts more in detail.
In order to reduce or arrest this movement of the trypanosomes,
Plimmer and Bradford ^ recommend adding a drop of a i per cent,
solution of gelatine [or of a weak solution of cherry-gum] to the
blood.
Section 2. — Staining Methods.
In the fresh state the general form of trypanosomes, their move-
ments, and the action of physical and chemical agents upon them,
can be studied. In order to obtain, however, a clear idea of their
intimate structure, it is essential to study preparations stained by
a special method — namely, a mixture of eosin and methylene blue
in definite proportions. This mixture was first used by Romanowsky
for staining hsematozoa (the malarial parasite). It was applied to
the staining of trypanosomes in 1898 by Ziemann,* who thus stained
the nucleus and centrosome in the trypanosome of the frog. The
following year Rabinowitsch and Kempner^ stained T. lewisi by this
method; but the most beautiful results were obtained in igoo by
Wasielewski and Senn,^ also with T. lewisi. They used Nocht's
modification of Romanowsk5''s method.
The following method^ has given us excellent results :
1 We found this method useful in collecting together above the layer of red
corpuscles the trypanosomes from a rat or dog with nagana when the parasites
were more numerous than the red corpuscles.
2 Francis, Bull. No. ii, Hyg. Laby., U.S. Pub. Health and Mar. Hosp. Serv.
Washington, 1903.
^ Plimmer and Bradford, Ceittralbl. f. Bakter., I, v. 26, 1899, p. 440 ; [also
Quart. Journ. Micr. Sc, v. 45, 1901, p. 451.]
* Ziemann, Centralbl. f. Bakter., I, v. 34, 1898.
'' Rabinowitsch and Kempner, Zeitschr.f. Irlyg., v. 30, 1899, p. 251.
•" Wasielewski and Senn, Zeitschr. f. Hyg.., v. 33, 1900, p. 444.
'' A. Laveran, Compt. Rend. Soc. Biol., June 9, 1900.
TECHNIQUE FOR STUDY OF THE TRYPANOSOMES g
The blood is spread in a thin layer on a glass slide witlr-the
edge of a visiting-card [or of another microscope slide] ^ried very
rapidly, and fixed in absolute alcohol for five to ten minutes. The
follovi^ing solutions should be prepared beforehand :
1. Methylene blue with silver oxide or Barrel blue. Take 50 or
60 c.c. distilled water in a flask of about 150 c.c. capacity, and add
some crystals of silver nitrate. When these are dissolved, fill the
flask with a concentrated solution of caustic soda and shake. A
precipitate of silver oxide is formed. This is washed several times
with distilled water, so as to get rid of any silver nitrate or excess
of soda. A saturated watery solution of methylene blue (' medicinal
methylene blue,' Hoechst) is then poured on to the silver oxide and
allowed to remain for a fortnight, the flask being shaken from time
to time.
2. Watery solution of eosin, i per 1,000 ('water-soluble' eosin,
Hoechst).
3. Solution of tannin, 5 per cent., or, better, a solution of tannin-
orange, which can be obtained ready made up.
The staining mixture is prepared at the time of using, according
to the following formula :
Solution of eosin (i per 1,000) ... ... 40.0.
Borrel blue ... ... .. ... ... i c.c.
Distilled water ... ... ... ... 6 c.c.
The mixture is at once poured into a flat dish, such as a Petri dish,
or, better, a square or oblong dish with sloping bottom- _apficially
nradefur Th^^urpoSE^^^ The slide on which the blood-film has
been spread and fixed is placed film downwards in the staining
solution (a piece of glass rod or a projection from the bottom of the
dish preventing the slide from touching the bottom, where a pre-
cipitate nearly always forms), and left there for five to twenty
minutes. Five to ten minutes' staining is long enough for most
trypanosomes, especially for the mammalian parasites ; twenty
minutes' staining is necessary for certain species — e.g., T. lewisi,
particularly when undergoing reproduction. After removal from
the staining solution the slide is well washed in a large quantity
of water J^r by blowing a strong stream of water on the film with a
wash-bottle], then treated with the solution of tannin for several
minutes, again washed in excess of water, and finally in distilled
water and dried. If a precipitate is formed, which would render
microscopical examination difficult, wash the film with oil of cloves,
then with xylol, and gently rub the surface of the preparation with a
piece of soft linen soaked in xylol.
^ [Such dishes, made of vulcanite, each to take one slide 3"Xi", have been
made at the suggestion of Dr. A. C. Stevenson by Messrs. Townson and Mercer,
of 89, Bishopsgate Street, E.C. We have found these dishes extremely useful,
especially for the prolonged staining of parasites, such as the trypanosomes and
the Treponema pallidum (Spirockata pallida) of syphilis.]
10 TRYPANOSOMES AND THE TRYPANOSOMIASES
The preparations keep better uncovered than if covered with
balsam or cedar-wood oil, in which case they rapidly lose their stain.
When the staining has been successful, the protoplasm of the
parasite is pale blue ; the nucleus, flagellum, and edge of the
undulating membrane are purplish ; the centrosome is deep violet^
a little different from the nucleus ; the undulating membrane is
unstained, or stained a very pale blue (see coloured plate). The red
corpuscles are pink, the nuclei of the leucocytes dark purple.
Equally good results are obtained with a mixture of azure
blue II and eosin. This mixture has been strongly recommended
by Giemsa,^ and Griibler supplies the blue prepared according to
Giemsa's directions. We have modified the method as follows :" Dry
and fix the film in absolute alcohol, then stain for ten minutes in —
Watery eosin (i per 1,000) ... ... ... 2 parts.
Watery solution of azure blue II (i per 1,000) i part.
Distilled water 8 parts.
Wash in water ; treat with 5 per cent, tannin for two to three
minutes ; wash again and dry. By this method we have obtained
good specimens of the trypanosomes of nagana and caderas.
Finally, we have used the powders prepared by Jenner, Leish-
man, J. H. Wright, etc., by mixing together solutions of eosin and
methylene blue, collecting the precipitate formed, and, after washing
thoroughly in distilled water, drying and pulverizing. The powder
is dissolved in absolute methyl alcohol, and is then ready for use.
In staining blood-films by this method, preliminary fixation of the
film is unnecessary.
[Leishman's stain answers admirably for trypanosomes, as well as for
the malarial parasite, piroplasms, the ' Leishman body ' of kala-azar and
tropical splenomegaly (see Chapter III.), and other chromatin-containing
parasites. It is best used as follows : Having obtained a blood-film or a
smear of an organ or tissue in the ordinary way, draw two lines with a
wax pencil (preferably blue, as with the other colours the wax tends to
float off) across the whole width of the slide, one on either side of the blood-
smear. This prevents the stain from running all over the slide, so that
1 Giemsa, Centralbl.f. Bakter., I, Orig., v. 37, igo2, p. 308.
[Giemsa's solution is prepared as follows: Take azure Il-eosin, 3 grammes,
and azure II, 0'8 gramme ; dry and powder. Dissolve at 60° C. in 250 grammes
chemically - pure glycerine, shaking the mixture to hasten solution. Add
250 grammes methyl alcohol, previously warmed to 60° C. ; shake, leave standing
for twenty-four hours at room temperature, and filter.
To use, fix air-dried films in ethyl alcohol, or, more quickly (two to three
minutes), in methyl alcohol ; dry with blotting-paper. Dilute the stain with water
in a wide graduated vessel, shaking the mixture. Use I drop of stain (dropped
from a drop-bottle) to about i c.c. distilled water, preferably warmed to 30° or
40° C. When properly mixed, pour the freshly diluted stain on to the film, and
leave on for ten to fifteen minutes (or the staining may be done in the small dishes
mentioned on p. 9). I hen wash in a stream of water, blot, dry, and mount in
balsam. Giemsa states that it is not advisable to use his solution in the way that
Leishman's stain is used. .
If an alkaline solution of the stain is required, add to 10 c.c. distilled water
(before diluting the stain) i or 2 drops of a i per cent, solution of potassium
carbonate.]
2 A. Laveran, C. R. Soc. Biol., March 7, 1903, p. 304.
TECHNIQUE FOR STUDY OF THE TRYPANOSOMES ii
less stain is necessary, and a cleaner preparation is ultimately obtained.
Without previous fixation, run a few drops of stain on to the film from a fine
pipette (5 to ID drops, according to the size of the film), and after thirty
seconds run on double the number of drops of distilled water — again from
a pipette^taking care that the water does not overstep the wax boundary
lines. Tilt the shde carefully to mix the stain and the water, and allow
the diluted stain to act for five to fifteen minutes. The stain is then
poured away, the film is washed for ten or fifteen seconds in distilled
water in a beaker, or blown on from a wash-bottle, and allowed to dry in
the air. The slide may be preserved uncovered, or it may be covered in
the ordinary way with a coverslip and xylol balsam, the latter, however,
causing the stain to fade after a time.]
[Marino's 1 stain also gives very good results with trypanosomes. The
alcoholic solution is obtained by dissolving in pure methyl alcohol the
precipitate formed by adding an aqueous solution of eosin to an alkaline
solution of methylene blue and azure blue in certain proportions.^ Four to
8 or 10 drops of the alcoholic stain are run on to the film (the number of
drops varying with the size of the film), and left on for three minutes.
Then double the number of drops of an aqueous solution of eosin
(0-05 gramme to 1,000 c.c. water) are added, and left on for two minutes,
after which wash, dry, and mount. Some trypanosomes, such as those of
birds and fishes, require rather longer to stain well — four to ten minutes
with the blue, and eight to twenty minutes with the eosin.]
If it be desired to stain a film rapidly, or if these special stains be
not at hand, an alcoholic solution of fuchsin, or, better, a watery
solution of magenta, or, better still, a solution of carbol thionin,
may be used. Staining takes place rapidly, often in less than a
minute. The nucleus, flagellum, and centrosome are stained more
deeply than the protoplasm, and in this way sufficiently good results
can be obtained when one wishes merely to ascertain the presence of
the trypanosomes and their relative numbers.
By Heidenhain's method (hasmatoxylin and iron alum) the
nucleus, centrosome, and flagellum are stained darker than the
■protoplasm, but of course are less distinctive than when stained by
our method or that of Romanowsky [or Leishman, Giemsa, etc.], in
which they assume a tint different from that of the protoplasm.
The methods of fixation and staining just described for blood
will answer for other liquids which may contain trypanosomes, such
as the blood-stained oedema fluids, cerebro-spinal fluid, culture
media, anaemic blood, or blood diluted with salt solution or sodium
citrate. In these cases, however, fixation is never so perfect as with
pure blood ; often the trypanosomes in these liquids appear vacuo-
^ [Marino, Ann. Inst Pasteur, v. 18, 1904, pp. 761-766.]
^ [The directions for preparing the stain are as follows : Take an aqueous solu-
tion of methylene blue and azure blue (methylene blue, 05 gramme ; azure blue,
0'5 gramme ; water, 100 c.c.) and mix with an aqueous solution of sodium carbonate
{o'5 per cent.). Keep the mixture in the 37° C. incubator for one to two days, or,
betl:er,'in the thermostat at a higher temperature ; then add an aqueous solution of
eosin to the blue mixture. The best strength of eosin solution varies with the
quality of the blue, and must be ascertained by actually trying the effect of different
strengths (o'( to 0'3 per cent.). The eosin-blue mixture is then filtered, and the
precipitate obtained is soluble in water and in methyl alcohol. The alcoholic
solution mentioned in the text contains 0*04 gramme of the dried precipitate dis-
solved in 20 c.c. pure methyl alcohol.]
12 TRYPANOSOMES AND THE TRYPANOSOMIASES
lated. This is particularly the case with the trypanosomes in the
cerebro-spinal fluid of sleeping sickness patients, so much so that at
first we looked upon this as a characteristic feature of the sleeping
sickness trypanosome. The examination of the same trypanosome
in the blood, however, soon showed that such was not the case.
When the trypanosomes are very scanty in the blood, it is best
to make thick smears, from which the haemoglobin is subsequently
dissolved out.^ In Ross's method « the thick blood-film is dried and
stained by one of the methods mentioned above without previous
fixation. The watery solutions of the stains dissolve out the hasmo-
globin, at the same time staining the leucocytes and the parasites.
This method is specially to be recommended for mammaHan blood,
which often contains very few parasites. By this method, however,
the blood-film is often washed away, and, moreover, the trypano-
somes are very deformed and often diificult to recognise.
Ruge^ has advised fixing the blood before staining by means of a
2 per cent, solution of formalin, to which is added acetic acid to the
extent of o"5 to i per cent. Fixing by this method does not prevent
the subsequent solution of the haemoglobin.
The following method has yielded good results in our hands :
fixing in absolute alcohol, then dissolving out the haemoglobin with
I per cent, acetic acid.
[Bradford and Plimtner* got the best results by fixing with osmic and
acetic acid vapours (osmic acid, 2 per cent., and glacial acetic acid, equal
parts), and staining with a mixture of methylene blue and erythrosin.
In the case of cerebro-spinal fluid, lymphatic gland juice, and intestinal
contents of flies containing trypanosomes, it is often difficult to stain the
chromatin. Gray and Tulloch^ overcame this difficulty by fixing the
films while still wet in osmic acid vapour, then adding fresh blood-serum,
as recommended by Leishman for sections (see below). After washing ofl"
the serum, the films were stained as usual by Leishman's stain.]
[Staining Trypanosomes in Sections. — For staining trypanosomes
and other chromatin-containing parasites in sections, Leishman" recom-
mends the following method : Paraffin sections (stuck on slides or
coverslips), after treating with xylol and spirit, are washed in water and
carefully blotted ; fresh blood-serum is added and allowed to remain on for
five minutes ; the excess is then removed by blotting and the rest allowed
to dry on. The stain is mixed — 2 parts ' Leishman ' to 3 of distilled
water — and poured on the section, which is then covered and left for one
to one and a half hours. It is advisable to put on fiesh stain once or twice
during that time. The stain is poured off and the section washed in
distilled water. With a low power, the cell nuclei should be almost black.
Decolourize and differentiate, using first a i in 1,500 solution of acetic acid,
then a i in 7,000 solution of caustic soda. The acid removes excess of
blue, the alkali excess of eosin, and the solutions are used alternately until
1 The method, which consists in dissolving out the hasmoglobin with water or
water acidulated with acetic acid, in order to show up any parasites which may be
in the blood, is an old one. It has been recently reintroduced by Ronald Ross.
2 Ronald Ross, Lancet^ January 10, 1903, p. 86.
^ Ruga, Deutsche vied. Wochenschr., March 19, 1903, p. 205.
* [Bradford and Plimmer, Quart. Journ. Micr. Sc., v. 45, pp. 451, 452.]
° [Gray and Tulloch, Sleeping Sickness Comm. Reports, No. 6, p. 286.]
^ [Leishman, /o urn. Hyg., v. 4, 1904, pp. 434-436.]
TECHNIQUE FOR STUDY OF THE TRYPANOSOMES 13
the desired contrast stain is got, as seen under a low power. When the
cell nuclei of the tissue are a deep Romanowsky-red colour, and the rest of
the tissue a very pale pink or light blue, wash well in distilled water, drain
and blot off excess of water, dehydrate rapidly with absolute alcohol, clear
with xylol, and mount in balsam.]
[Giemsa's stain used as in Leishman's method, safranin and indigo
carmine (Neporojny and Jakimoff), and polychrome methylene blue
(Marchand and Ledingham, Mott, Halberstaedter), also stain the trypano-
somes well in sections.]
[Halberstaedter 1 gives the following details of the method used by him :
Small pieces of tissue are fixed immediately after death in sublimate-
acetic mixture (concentrated watery solution HgClg, 150 parts ; distilled
water, 150 parts ; glacial acetic acid, 4 parts) for twelve to twenty-four
hours ; then washed in running water for twenty-four hours, and, after
passing through alcohol, etc., embedded in paraffin. Stain thin sections for
ten minutes in polychrome methylene blue, wash in water, treat for a fey
seconds in absolute alcohol (not too long), clear with xylol, and mount in
balsam.]
Section 3.— Preservation in vitro and Cultivation of
Trypanosomes.
Until quite recently no method of cultivating trypanosomes was
known, but they could be kept alive in vitro for a variable time,
either in hanging-drop or in sterile tubes. The essential condition
is to obtain the blood aseptically from the heart or carotid artery in
the case of small animals, from the jugular vein in larger animals.
It is at once mixed with physiological saline, and defibrinated in
sterile flasks containing glass beads, or, better still, it may be mixed
with citrated salt solution (NaCl 5 grammes, sodium citrate
5 grammes, water 1,000 c.c.) to prevent coagulation.
Even under these conditions most parasites can be kept alive only
a few days, a notable exception being T. lewisi, which will live for a
considerable time if kept in the ice-chest. The addition of different
serums keeps the trypanosomes alive a little longer.
McNeal and Novy^ in 1903 succeeded in cultivating trypano-
somes — first T. leivisi, and later T. brucei. We have also been able
by using McNeal and Novy's method to cultivate T. lewisi and
T. evansi.^
The culture medium employed is comparatively simple. It
consists of nutrient agar containing i to 3 per cent, of peptone,
to which defibrinated blood is added. From certain observations
of McNeal and Novy it appears that the haemoglobin plays an
important part in this medium, for if the haemoglobin undergo any
change, the medium is useless and growth in it will cease.
Agar prepared in the ordinary way is cooled down to 59° C,
' [Halberstaedter, Centralbl.f. Bakter., v. 38, 1905, pp. 525-532.]
"- McNeal and Novy, ' Contributions to Medical Research,' dedicated to V. C.
Vaughan, June, 1903 ; Journ. Infec. Dis., v. i, January 2, 1904.
^ [Recently Novy and McNeal and Thiroux have succeeded in cultivating bird
trypanosomes, Thiroux that of the mouse, Petri that of the rabbit, and Bouet that
of the frog.]
14 TRYPANOSOMES AND THE TRYPANOSOMIASES
and two or three times ^ its volume of defibrinated blood taken
aseptically from a rat, guinea-pig, or, more commonly, a rabbit, is
added to it. The culture tubes are sloped in the usual way, and the
medium allowed to solidify. As soon as this has occurred, the tubes
are placed upright, so as to ensure the rapid formation of a large
quantity of water of condensation, which collects at the bottom of
the tubes. This water of condensation is inoculated with a loopful of
blood from an infected animal or of a previous culture.
As the culture tubes are often kept for months, precautions are
necessary to prevent the evaporation of this water of condensation.
If the cultures are made at 20° to 25° C, McNeal and Novy at first
recdmmended sealing the tubes with wax ; now they use thick
rubber caps for the tubes, which we have also found to answer well.
If incubated at 34° to 37° C, McNeal and Novy put the tubes in a
large desiccator or apparatus such as is used for anaerobic cultures
containing some cotton-wool well soaked in perchloride of mercury
solution.
In the water of condensation in blood-agar tubes, the trypano-
somes grow either at the room temperature or in the incubator
at 34° to 37° C. In this way pure cultures can be obtained.
Bacterial contamination usually causes rapid death of the trypano-
somes ; nevertheless we have succeeded in keeping T. lewisi alive
and virulent for more than a fortnight in a tube in which many
organisms had developed. [Novy and Knapp- also found that
exceptionally some bacteria are not unfavourable to trypanosomes,
and that mixed cultures may be kept alive for six months or more.]
[For the isolation of trypanosomes from accompanying bacteria they
recommend the following method : With a small glass spatula take a little
of the mixed growth, and spread it in a series of streaks on solidified
blood-agar in six Petri dishes, using dishes which can be effectually sealed
by means of a wide rubber band. At the end of ten to twelve days at
room temperature the last plate or two of the series will show isolated
colonies of the trypanosomes, which can then be subcultivated in the
ordinary way in test-tubes.]
[Mathis^has recently improved upon Novy and McNeal's original
medium by heating it to 75° to 100° C. for half to one and a half
hours one or more times. The advantages claimed for this modifica-
tion of the original medium are — (i) that it sterilizes the medium,
which therefore need not be prepared so carefully ; (2) that it is
fixed or more uniform in composition, and can therefore be prepared
long in advance ; and (3) that it alters the blood of various animals,
such as the goose, rabbit, dog, and goat, so that they are all
equally serviceable.
1 T. lewisi, according to McNeal and Novy, grows in media containing i part
of blood to 5 or even 10 parts of agar ; but it prefers media rich in bluod, the
optimum being apparently 2 parts of blood to 1 of agar. T. brucei will only grow
in media containing at least as much blood as agar, the optimum mixture contain-
ing 2 to 3 parts of blood to i of agar. Even under these conditions cultures are
difficult to obtain. (See special chapter.)
2 [Novy and Knapp, _/d/iir«. Hyg., v. 6, 1906, p. iii.]
^ [C. Mathis, C. R. Soc. Biol., v. 61, 1906, pp. 550-552.]
TECHNIQUE EOR STUDY OF THE TRYPANOSOMES 15
This modified medium was found most useful for the non-
pathogenic trypanosomes, less so for the pathogenic. Thus T. rota-
toritim in two days showed numerous trypanosomes, and in seven
days they were very abundant. T. lewisi in two days showed fairly
numerous characteristic rosettes ; in one month the culture was very
rich in trypanosomes, and intraperitoneal injection infected rats in
less than three days.]
Section 4. — Inoculation Experiments.
Nothing verj' special need be said upon this point. Blood (pure,
defibrinated, or citrated), blood-stained oedema fluid, or cerebro-
spinal fluid containing trypanosomes, may be injected with an
ordinary hypodermic syringe or pipette. In the case of the patho-
genic trypanosomes the inoculation may be made subcutaneously
(or even to the freshly injured surface of an abrasion), intra-
peritoneally, or intravenously, with hardly any difference as to the
final result. The mode of inoculation merely affects the period of
incubation, parasites appearing in the blood sooner after an intra-
peritoneal than after a subcutaneous injection.
In the case of the non-pathogenic trypanosomes (T. lewisi, trypano-
somes of fishes), intraperitoneal inoculations appear to be the most
reliable.
Certain trypanosomes {T. equiperdum of dourine) can apparently
be inoculated upon healthy non-excoriated (?) mucous surfaces.
Inoculation through the mouth or stomach does not occur with
any try.panosome, except when the buccal mucous membrane pre-
sents recent abrasions.
Trypanosomes appear to be virulent in the minutest doses, a
single trypanosome sufficing to bring about an infection. It is
merely a question of the duration of the incubation period. For
example, in the case of nagana, the incubation period may be less
than twenty-four hours after the intraperitoneal inoculation of many
parasites ; on the other hand, it may be as long as ten days when
few are present in the material injected. The difference is still more
marked in the case of other trypanosomes.
Before inoculation it is as well to make sure, by microscopic
examination, of the condition of the trypanosomes to be injected.
The incubation period and, in the case of trypanosomes that have
been kept, the success of the inoculation depend on the condition of
the parasites injected.
Finally, the inoculation of a large quantity (up to 10 c.c.) of blood
or other fluid is always indicated when the trypanosomes have not
been visible on microscopic examination (as in the case of ruminants
and pigs infected with or suspected of nagana, and horses suspected
of dourine). The inoculation should be made into a susceptible
animal — rat, mouse, or dog in the case of nagana ; dog in the case of
dourine. If rats or mice are used, several must be inoculated.
CHAPTER III
COMPARATIVE STUDY OF THE TRYPANOSOMES
Section 1.— General and Comparative Morpholog-y.
We shall begin by giving a general account of the structure of
trypanosomes, such as appears to us to embody the results of
recent observations. Figures 2 and 3 show the 'principal varia-
tions in the form of trypanosomes, and at the same time bring out
clearly the features by which these parasites may be recognised,
at least in the form we shall call adult. There is a spindle-shaped,
more or less elongated, protoplasmic body containing two chromatic
masses — one small mass, which we call the centrosome, generally
placed at the posterior end ; the other, nearly always mesially
situated, which is larger and is called the nucleus. A folded
membrane, which is known as the undulating membrane, starts from
the centrosome, and runs along the protoplasmic body. Its thickened
border is generally prolonged anteriorly into a free part, constituting
the flagellum.
In the case of certain parasites found in the blood of fishes, for
which we have created a special genus, Trypanoplasma, several
peculiarities are to be noted : first, the undulating membrane, which
extends from one end of the body to the other, is prolonged
posteriorly into a free flagellum, while anteriorly it bends round and
reaches the end of a large elongated mass of chromatin, from which
the anterior flagellum also starts ; secondly, the protoplasmic body
does not contain a large and a small chromatic mass, but two masses
of almost the same size and about as large as the nucleus of the true
trypanosomes.
We shall now study more in detail the various parts of the
trypanosomes (using this term in its wider sense), pointing out at
the same time the variations found in different members of the
group.
The body proper is, as a rule, spindle-shaped. In certain
parasites found in the Batrachia this spindle is almost as broad as
it is longi (40 fj, by 60 /a), and the ends are rounded off, leading
1 In measuring trypanosomes, it is advisable to measure the width in the
region of the nucleus, taking into consideration the undulating membrane, and
the length including the flagellum. At the same time the length of the body and
of the free flagellum should be measured separately ; but these measurements are
16
COMPARATIVE STUDY OF THE TRYPANOSOMES 17
eventually to flattened forms with an ellipsoidal outline, which would
be a true geometrical figure were it not for a slight prolongation
anteriorly which accompanies the flagellum. We find the opposite
extreme in forms such as those seen in Fig. 2, /, where the body is
only T"5 /J^ wide, or, better still, in certain parasites of fishes, such as
those of the eel, which are 80 /j. long by only 2'5 fj- broad. Between
these two extremes there are many intermediate forms, some of
which are characteristic of certain species parasitic in reptiles or
birds, others not possessing any specific value. Thus, for example,
the trypanosomes of Batrachia may assume various forms — some
relatively thin (see Fig. 63, Chapter XVI.), which we give in Fig. 2
(j and 7), as types of ' stumpy ' forms ; also the broad forms of
T. lewisi (our ' thin ' type, Fig. 2, i) when reproduction is about to
take place.
The trypanoplasms are of medium length, the body being in the
form of a ribbon, which is constantly changing its shape.
Fig.
-Trypanosomes of Mammals and Batrachia — Trichomonas.
I. T. lewisi : n, nucleus : c, centrosome ; in, undulating membrane. These letters
have the same significance in the other figures. 2. T. briicei . 3 and 4. T. rota-
torium of Rana esciilinta (frog) : striated form (3) and flat form (4). 5. Trichomonas
intcstiiuilis, from the intestine of the guinea-pig : ii, internal rod ; 6, anterior tlagella.
(Magnification about 1,800 diameters.)
The shape and size of trypanosomes afford very good means of
diagnosing species.^ It must be remembered, however, in the case
of trypanosomes pathogenic for different species of animals, that
often difficult, for it is sometimes not easy to determine where the free flagellum
commences, so that there is in such a case a liability to err, which is not present
when the whole parasite (flagellum included) is measured. It is for this reason that
.we lay most stress upon that dimension (namely, total length) in differentiating
species.
[Lingard [Joio-n. Trap. Vet. Science, v. 1., igo6) suggests making the follow-
ing measurements: (l) Post-centrosomic part; (2) from the centrosome to the
posterior end of nucleus ; (3) length of nucleus ; (4) distance from the anterior
end of nucleus to anterior end of body ; (5) free flagellum. The sum of these
five measurements gives the total length. He also measures the ma.\imum width.
As pointed out in the first part of this note, however, it is often difficult, if not
impossible, to say where the body ends anteriorly and the free flagellum begins.]
^ [The recently described — probably se.Kual — morphological difterences in
various mammalian trypanosomes are referred to later on in this chapter.]
2
i8 TRYPANOSOMES AND THE TRYPANOSOMIASES
these tr3'panosomes show certain \'ariations in length, and even in
shape, according to the species of animal infected. Thus, T. brucet
is longer in Eqaidse than in experimental rodents ; it is more
stumpy in rats and mice than in dogs. It follows, therefore, that if
one wishes to compare two allied species of trypanosomes for
example, T. brucei and T. evansi — one should examine the parasites
in the blood of the same species of animal.
The anterior extremity is generally elongated ; it extends some
way along the flagellum, sometimes (as in the case of T. diiiwrphon
of horses in Gambia and of T. johnstoni of birds) even to its tip.
The posterior extremity varies very much in shape, not only
in different species of trypanosomes, but also in the same species, and
even in the blood of the same animal. Evidently this part of the
bod}- has a certain amount of plasticity or power of amceboid move-
FiG. 3. — Trypanosomes of Fishes.
I. T. remaki, var. parva : », nucleus ; c, centrosome ; 111, undulating membrane. These
letters have the same significance in the other figures. 2. T. remaki, var. magna.
3. T. soleis. 4. Trypanoplasma borreli : fa, anterior flagellum ; fp, posterior flagellum.
The anterior end is the lower one in the figure.
ment, by virtue of which it can elongate and shorten. None the
less it presents, in a given species, certain peculiarities which are
really s/)ccf)^c, but we must always be verj' careful in interpreting such
peculiarities.
Thus, T. lewisi (Fig. 2, /) is characterized by a long pointed
posterior extremity, like an acute-angled cone. In some cases this
part is almost as long as the rest of the body, whilst in others it is
relatively short. In the trypanosomes of the type brucei (Fig. 2, 2)
the posterior extremity is less slender and generally short ; it is
rarel}' pointed, but nearly always in the form of a blunt cone. In
the other pathogenic trypanosomes of mammals, the posterior end
is usually rounded off in the form of a hemisphere, and the centro-
some is very near the end ; but even in these species manj' of the
parasites have a bluntly conical end. It is, however, in the trypano-
somes of the Batrachia that the greatest variation in shape is seen.
Some have a posterior extremity as long as the rest of the body,
and at times it even appears to be prolonged into a flagellum, so
much does it taper off; in others, as has been mentioned before, the
end is rounded off in the form of an ellipse, and one often observes
COMPARATIVE STUDY OF THE TRYPANOSOMES 19
under the microscope the conical posterior extremity of a parasite
becoming rounded off.
The protoplasm stains more or less deep blue by our eosin-
methylene blue mixture.^ This is due to the presence of a great
number of barely visible very fine granules. The blue colour is
deeper with some trypanosomes than with others ; for example, the
pathogenic trypanosomes of mammals and those of fishes stain more
deeply than T. lewisi or other members of the same group. The
blue colour is never very uniform, and there are always paler areas
to be seen ; but we would draw attention to the fact that these clear
areas always appear to be irregularly distributed, and we have
never found, in the case of any particular trypanosome, anything
characteristic in their form or distribution.
The clear oval vacuole which authors have described in the
posterior part of certain trypanosomes, and which they identify with
the contractile vacuole of the non-parasitic Flagellata, has appeared
to us of variable form when present. Moreover, it is found especially
in preparations made from liquids other than the blood {e.g., blood-
stained oedema fluid, cerebro-spinal fluid in cases of sleeping sick-
ness), and the presence of this vacuole is doubtless due, as we have
said above, to the fact that we do not know how to fix these liquids
properly. These vacuolated forms are not found in the blood. One
cannot, therefore, attribute any specific importance to the presence
of these vacuoles, to their shape, or to their relation to the centro-
some.^
The protoplasm often contains chromatic granules stained deep
violet, very variable in number, shape, and size. They are generally
a little irregular in shape, but more or less rounded, and do not
exceed i /t in diameter. Seme species of trypanosomes do not possess
them ; in others they are scanty, and often localized to the immediate
neighbourhood of the nucleus ; in yet others they are immerous and
scattered throughout the body of the parasite. They are absent
from T. lewisi, are very scanty in T. dimorphon and T. evansi, less
rare and larger in T. brucei and T. equinum. In the latter species
sometimes one or two of the granules are more than i ^ci in diameter
and quite circular, in which case they may be mistaken for the
centrosome. Up to a certain point these granules are of value in
determining species, but too much weight must not be attached to
their presence, as this depends to a certain extent upon the condi-
tion of health of the animal under investigation. When the death
of an infected animal is approaching, the trypanosomes are usually
less vigorous, and their protoplasm contains more granules than
in the case of normal parasites. The same thing is seen in the
1 Throughout this description we shall refer solely to preparations stained by
this method (see p. 9 et seg.).
^ [I do not agree with the authors that 'vacuolated' forms are not normally
found in the blood; see footnote in Chapter XII. under the morphology of
T. gambiense ; also article by Woodcock, ' 'I'he Heemoflagellates,' in Quart. Journ.
Micr. Sc, V. 50, part i., April, 1906, pp. 211, 212.]
2 — 2
20 TRYPANOSOMES AND THE TRYPANOSOMIASES
trypanosomes from animals undergoing treatment with human serum
or arsenious acid.
These violet granules are almost the only ones seen in trypano-
somes. In addition, we may mention the non-staining granules
seen in T. rotatorium of the frog and the refractile non-stainmg
granule seen in T. lewisi in the blood of guinea-pigs. The refractile
granules seen in culture forms of T. brucei are undoubtedly of the
same nature.
In some trypanosomes one can distinguish fine longitudinal
striae, more or less marked, generally characterized by a linear
arrangement of the microsomic granules. These strias are apparently
quite superficial. They probably represent the broad, well-marked
striae seen in some forms of T. rotatorium. In this trypanosome the
striae are arranged in the form of a helix, the axis of the helix being
almost transverse and the stria; arranged in a longitudinal direction.
The body of the parasite appears to have no definite investing
membrane. We have been unable to make out around the body
a special layer of protoplasm, the so-called ectoplasm or periplast.^
It is only along the ridge formed by the undulating membrane that
the surface of the body presents any peculiarities, and these will be
referred to later on.
The nucleus [macronucleus, trophonucleus] — that is to say, the
larger chromatic corpuscule of trypanosomes — round or oval in shape,
is generally situated about the middle of the body. Rarely, as in
T. lewisi, it is situated in the anterior part of the body, which is a
diagnostic feature of that species of trypanosome. [In T. longo-
caudense (Lingard) of the rat, T. duttoni (Thiroux) of the mouse, and
in the bat trypanosome, the nucleus is also anteriorly placed. In
some forms of T. theileri the nucleus is situated behind the middle of
the body.] The size of the nucleus appears to be independent of the
size of the parasite ; for example, the nucleus of the large trypano-
somes of frogs is scarcely bigger than that of the thin trypanosomes of
mammals.
The nucleus appears as a collection of chromatic granules, stain-
ing purple by the ordinary methods. This collection of granules is
relatively compact, the granules being of various sizes and shapes,
and joined together by a feebly staining cement substance. No
network or nuclear membrane can be distinguished. It is a rela-
tively simple type of nucleus. Prowazek,^ who distinguishes four
types of nucleus among the Flagellata, considers this nucleus to be
of the simplest type.
^ [It is pointed out later on (pp. 24 and 6g) that Prowazek and others describe
the undoubted occurrence of an ectoplasmic layer in some cases.]
2 [Prowazek, Arch. f. Protistenkunde, v. 3, 1903, p. 195. But, according to
Prowazek's recent investigations, the nucleus of l . lewisi and T. brucei is very
complex, and resembles the complex nucleus originally described by Schaudinn
iri 7". noctucE. The nuclei of other mammalian trypanosomes are probably also
more complex in structure than has hitherto been supposed. (See the accounts
given later of T. lewisi and 7'. brucei.y]
COMPARATIVE STUDY OF THE TRYPANOSOMES 21
Usually the granules are scattered uniformly throughout the
nuclear mass. There are few exceptions : T. reniaki of the pike,
which has in the centre of the nucleus a clear space containing
a single large granule, the smaller granules forming a ring around
the central vacuole. Perhaps this is also the case in T. solece, but we
have seen too few specimens of it to be sure.
The nucleus always divides amitotically.^ Sometimes it elongates
hardly at all before dividing ; at others {e.g., T. brncei, Fig. 22, 2)
the nucleus elongates considerably and becomes rod-shaped, and,
finally, the intervening part where no chromatic granules are
present becomes constricted and obliterated. In such cases there
is a suggestion of mitotic division, but much less than in the micro-
nuclei of the ciliated Infusoria, for example.
The small chromatic body which we call the centrosome^ is
situated quite near the posterior extremity in many species of
trypanosome. But that position is not absolutely constant. At first,
in certain species {e.g., T. le-wisi of the rat), when the parasite has
just divided, the centrosome is close to the nucleus. In other
species — at least, in certain varieties — it occupies normally, and
without any reference to fission — -this central position near the
nucleus. This is seen in some forms of T. rotatorium of the frog
(Fig. 2, j) and in T. transvaaliense (Fig. 45, Chapter XL). In
these cases the centrosome is situated deep down in the interior of the
protoplasm.
The centrosome of true trypanosomes occurs as a small com-
pact and homogeneous mass of chromatin, staining a deep violet,
slightly different from the colour of the nucleus. It is generally
round, rarely elliptical, though it is frequently so in T. lewisi. In
size it is usually o'5 /x o'l fi, with one exception, the T. eqinnum of
caderas, in which the centrosome is only 5- /a in diameter, and is
difficult to recognise at the extremity of the flagellum. Often the
centrosome is surrounded by a clear space or halo, which makes it
appear the more distinct. When the centrosome is fairly large this
halo is not visible ; the centrosome then occupies the whole width
of the parasite, and sometimes appears even to extend beyond it,
doubtless owing to its refractile character in stained specimens.
The centrosome divides in a simple fashion. It elongates,
becomes halter-shaped, and finally the two halves separate. Some-
times, as in T. lewisi, it elongates transversely to the long axis of
the body ; more often, as in T. brucei and others, it lengthens longi-
tudinally, so that the two resulting centrosomes are situated the
'■ Wasielewski and Senn have represented, in a case of multiple division of
T. lewisi, nuclear division with equatorial plates. We have never seen anything
like this. [We shall see later, however, that more complex forms of nuclear division
have been described in the case of T. noctiicc (Schaudinnj, T. lewisi, and T. brucei
(Prowazek).]
^ [This little body, the significance of which has been much discussed (see
Section 5), is also called the micronucleus, the blepharoplast, and the kineto-
nucleus by other authorities.]
22 TRYPANOSOMES AND THE TRYPANOSOMIASES
one in front of the other in the long axis of the parasite (Fig. 22,
Chapter VI.).
In the species which we have placed in the genus Trypanoplasma,
the two chromatic masses are about equal in size, each being as large
as the nucleus of an ordinary trypanosome. They are laterally
placed, often along two transverse diameters near together. They
differ a httle in their staining reactions. Thus, according to Miss
Plehni, who has recently described in the carp a new species of this
genus, the chromatic body in connection with the ilagella (which
we identify with the centrosome of Trypanosoma) stains deep violet,
like the nuclei of the carp's erythrocytes ; the other body (the true
nucleus) stains lilac, like the nuclei of the leucocytes and the blood-
platelets. Amongst the numerous trypanosomes which we have
examined we have never seen an arrangement intermediate between
that found in Trypanoplasma and that observed in Trypanosoma.
Originating in the centrosome of the true trypanosomes is a very
clear filament, which runs along the edge of the undulating mem-
brane, and is then usually prolonged beyond the end of the body
into a free part. We shall call this filament throughout its whole
length the flagellum. In it three parts can be distinguished : the
first part or root, which is very short, and extends from the centro-
some to the undulating membrane ; the second, which runs along
the edge of the undulating membrane ; while the third part is the
free flagellum. The flagellum has the same appearance and the
same chromatic reaction throughout. It stains purple, exactly like
the chromatic granules of the nucleus, differing slightly from the
deep violet colour of the centrosome.
The connection between the flagellum and centrosome is un-
doubted. In those forms in which the centrosome is surrounded by
a clear space, the flagellum appears to end at the border of that
clear area ; but it is, nevertheless, connected with the centrosome, as
the examination of other trypanosomes in stained preparations will
demonstrate. The flagellum, isolated from the undulating membrane
and the rest of the body of the parasite, nearly always remains
attached to the centrosome.
The undulating" membrane appears as a ridge or crest extending
laterally from the body of the parasite along a variable part of its
length. Its longitudinal extent along the body of the parasite
obviously depends upon the position of the centrosome. If the latter
is near the posterior extremity, as is usually the case, the undulating
membrane extends along the greater part of the body of the parasite ;
if, on the other hand, the centrosome is near the middle of the body,
1 M. Plehn, Arch. f. Protistenkunde, v. 3, 1903, pp. 175-180. Miss Plehn has
since written us (March 26, 1904) that she was mistaken about the chromatic body
in relation with the undulating membrane. We transpose, therefore, what the
author says about these two bodies. The same facts have also recently been
made out by Leger (C. R. Acad. Sciences, v. 138, March 28 and April 4, 1904),
and agree with our own recent observations.
COMPARATIVE STUDY OF THE TRYPANOSOMES 23
the undulating membrane will be found only along the anterior half
of the trypanosome.
The undulating membrane is always very thin, much more so
than its border, which is constituted by the flagellum. We think it
is always composed of protoplasm identical with that of the body
itself; we have never made out any special protoplasm, periplast or
otherwise. It is always homogeneous ; we have never seen any
reinforcing striae as occur, for example, in the Trichomonas (Fig 2, 5).^
The variations in the membrane amongst the different species
depend largely upon the number of folds which it exhibits. The
largest number of folds is seen in T. rotatoriiim (Fig. 2, 3 and ^),
T. avium (Fig. 60, Chapter XIV.), and T. granulosum of the eel. The
pathogenic trypanosomes of mammals of the type brucei have
membranes more folded than the non-pathogenic trypanosomes of
the type lewisi. Finally, there are forms (T. dimorphon, etc.) in which
the flagellum is so closely applied to the body that the membrane is
reduced almost to nothing. These few examples are sufficient ; a
study of the numerous figures in this book is of more value than any
description.
The undulating membrane is often prolonged anteriorly beyond
the body itself; or, in other words, the body is represented
anteriorly only by the continuation of the undulating membrane, of
course with the flagellum along its edge. Generally a free portion
of the flagellum, of variable length, extends beyond this part (longer,
for example, in T. lewisi than in the pathogenic trypanosomes of
mammals), the dimensions of which furnish specific characters of a
certain value. Sometimes the flagellum has the same thickness right
up to the end ; at other times it gradually tapers off. This free part
of the flagellum may be absent, however, as in T. dimorphon (Fig. 28,
Chapter VII.) and T.johnstoni (Fig. 61, /., Chapter XIV.). It is also
the case in a species which Broden has recently found in mammals
(sheep and donkey) on the Congo. A similar appearance is observed
in certain forms of T. rotatoriiim, in which case it seems to be due to
a change of shape — into a spherical iorm, with retraction of the
undulating membrane — in a certain number of the parasites after
leaving the frog's bloodvessels.
Even amongst species of the type brucei where the majority of the
parasites have a free flagellum, some occasionally have no free
flagellum. This is probably connected in some way with repeated
subdivision {vide infra).
Taking all the known forms into consideration, it is impossible to
attach great importance {e.g., a generic importance) to the presence
or absence of a free flagellum. For example, we should not on
that account alone put T. dimorphon in a genus different from the
T. gambiense or T. brucei.
' [Since Schaudinn's original description of the ectoplasmic origin of the undu-
lating membrane in T. nociua, and of the occurrence of reinforcing striae in this
membrane, several observers have described a similar structure in other trypano-
somes.]
24 TRYPANOSOMES AND THE TRYPANOSOMIASES
In forms without free flagellum the anterior extremity of the
body tapers off just as much as in those with flagellum.
[Since the interesting and very revolutionary observations of
Schaudinn upon the blood parasites of the owl (Athene noctua ; see
Section 4), in which he describes sexual forms as well as a highly
complex structure of the parasites, Ziemann, Prowazek, and others,
have described analogous sexual and ' indifferent ' forms, and also
great complexity of structure, in several of the mammalian trypano-
somes. Prowazek's first observations were upon T. lewisi, and in
Chapter IV., Section 3, the reader will find an account of the results
obtained by Prowazek with this try.panosome as regards the sexual
forms, the presence of an ectoplasm and of myonemes, and the
complexity of the nucleus.]
In Trypanoplasma the undulating membrane runs along the
whole length of the parasite, but it is only clearly recognizable by its
border (formed by the flagellum), which follows the convex surface of
the body. The membrane has few folds, is not prominent, and in
certain places is very closely applied to the body. Anteriorly, after
coursing along the anterior rounded end of the body (see Fig. 3, ^),
it turns back again along the concave side of the body to within a
short distance of the centrosome, where it appears to be inserted.
Posteriorly, the thickened edge of the membrane gives rise to the
free posterior flagellum. Another free flagellum is seen anteriorly,
which is inserted in front of the centrosome, like the undulating
membrane. Are the relations between the centrosome and the
flagella as close as in the case of the true trypanosomes ? We have
no definite observations on this point.^
The longitudinal division of the flagellum in trypanosomes has
been studied with the greatest detail. We may note in passing that
it is the first definite observation of division of the flagellum amongst
the flagellates.
Division always starts in the centrosome. Two modes of division
are clearly recognisable : (i) That seen in T. lewisi, where only the
root of the flagellum is duplicated. This root is seen to broaden out
at first, then to divide into two. (2) That seen in the majority of
the other trypanosomes, where the duplication of the flagellum and
the undulating membrane proceeds gradually from the centrosome
to the extremity of the undulating membrane. Sometimes the free
flagellum is also duplicated.
In the first case the short flagellum thus formed grows in a
centrifugal manner, beginning from its centrosome.
[From Schaudinn's observations upon T. noctuce of the owl, it
appears that the whole of the new flagellar apparatus is developed
^ [In Trypanoplasma borreli Leger has described a centrosomic granule
('diplosome ') at the base of each flagelhim ; and Keysselitz suspects the presence
of similar granules in Trypanophis. Prowazek also frequently figures such a
centrosomic granule, situated between the centrosome and the base of the
flagellum, in both T. lewisi and T. brucei^
COMPARATIVE STUDY OF THE TRYPANOSOMES 25
independently of the original ilagellum — from the daughter centro-
some. Prowazek states that this is also the case with T. lewisi and
and T. brucei (see Chapters IV. and VI.). McNeal has described
the same phenomenon in culture forms of T. brucei. There is some
doubt, therefore, whether the flagellum of trypanosomes does really
split, although blood-films in which fission forms occur certainly
give one the impression that the flagellum is actually splitting.]
There remains little to be said about the multiplication of
trypanosomes, since we have already spoken about the division of
the nucleus, centrosome, and flagellum. The simplest mode of
division, as seen in the pathogenic trypanosomes of mammals and
the trypanosomes of fishes, is a longitudinal division into equal or
subequal parts. It begins in the centrosome,^ follows in the nucleus
and undulating membrane, and ends in the protoplasm (Fig. 22,
Chapter VI.).
In T. lewisi, and also undoubtedl)' in certain trj'panosomes of
birds, the process of division is apparently more complicated. We
shall be content to mention here only those points which appear to
us to be the most important for the comprehension of the type,
Trypanosoma, leaving the consideration of less important details to
the chapter dealing specially with T. lewisi.
The trypanosomes first enlarge considerably, and then divide
longitudinally into two unequal parts. One of the resulting trypano-
somes has a nucleus and centrosome exactly like those of its con-
gener, but has less protoplasm, and a short flagellum without
undulating membrane. Those forms without undulating membrane
can divide again, and give rise, by longitudinal and equal division of
all their parts, to others similar to themselves— namely, small fusiform
parasites, with the centrosome near, and sometimes even in front of,
the nucleus, and without undulating membrane. In cultures only these
forms are found. These forms in their turn can give rise to others of
the adult type with undulating membrane, probably by displacement
backwards of the centrosome and the elongation and lateral dis-
placement of the flagellum, which comes to be the border of a
projection from the side of the body. As we shall see later on, these
rat trypanosomes thus pass through a stage which is the adult
condition in other flagellates — the genus Herpetomonas-
All the flagellates parasitic in the blood known up to the present
can be grouped in two genera :
I. Trypanosoma, Gruby, 1843 (Laveran and Mesnil, 1901,
amended):'- Flagellates with fusiform body, presenting laterally an undu-
lating membrane, whose thickened edge ends posteriorly , in the posterior
half of the body, in a centrosomic corpuscide {clearly differing from the
nucleus in structure), and anteriorly is usually prolonged as a free
1 [Although the centrosome is usually the first to divide, division may some-
times begin in the nucleus.]
- We reproduce here, with very slight alteration, the description we gave in
1901 (C. R. Acad. Sciences, v. 133, p. 131).
26 TRYPANOSOMES AND THE TRYPANOSOMIASES
flagelhim. Binary longitudinal division into equal or unequal parts.
Certain species pass through a stage without undulating membrane.
Parasitic in the blood of all classes of vertebrates.^ A very large
number of species known.
2. Trypanoplasma, Laveran and Mesnil, 1901 (amended 1904) :
Flagellates with elongated body, presenting laterally an undulating
membrane, whose thickened edge is prolonged posteriorly as a flagellum,
and turns back anteriorly to reach a mass {centrosome) which is as large
as, and has up to a certain point the same structure as, the nucleus. An
anterior free flagellum has its origin in the same mass. Multiplication
is probably by binary equal longitudinal division. Parasitic in the blood
of fishes.^ Several species known. ^
The differences between the characters of the two genera are
so clear and sharply defined* that the necessity of dividing the
flagellated hasmatozoa into these two genera is unquestionable.
Is it necessary to create a larger number of genera ? The various
species^ of the genus Trypanoplasma are closely allied, therefore no
difficulty arises on that point. As to the species of the genus
Trypanosoma, there are (as we have already shown in previous pages,
and as a study of our figures will also demonstrate) all stages of
transition from one to another. A further generic subdivision, based
on any single characteristic or group of characteristics, appears to
us quite impossible.^
In another paragraph we shall justify the generic names we use.
[Woodcock'^ places the flagellate of the owl, the life cycle of which has
been so fully worked out by Schaudinn, in a new genus {Trypanomorpha).
Llihe, in his article on the blood-parasites in Mense's ' Handbuch der
Tropenkrankheiten,' v. 3, igo6, 'creates the new genus Trypanozoon
(with flagellum anterior) for all the mammalian trypanosomes. On the
other hand, he thinks (without giving reasons for so doing) that the
1 [We shall see later that trypanosomes have been described in tsetse-flies,
though, of course, it is possible that the flies had obtained their trypanosomes by
sucking the blood of some vertebrate which contained the parasites.]
^ [Leger has since described (in C. R. Soc. Biol., v. 58, 1905, p. 511) an
inteslinat trypanoplasm in fishes. In the same paper he expresses the opinion
that Keysselitz's new genus Trypanophis (see footnote 4) is so like Trypano-
plasma that the former should be included in the latter.]
^ [In the original it is stated that two species are known, but since that was
written several other species have been described and named (see Chapter XVII.).]
^ Poche has recently discovered (Arbeit, a. d. zool. Inst, zu Wien, v. 14, 1903,
p. 307) amongst pelagic Ccelenterata of the group Siphonophora, a flagellate
with undulating membrane which he has called I'rypanosoma grobbeni. The
subject has recentiy been further studied by KeysseHtz at Rovigno. In his paper,
which has recently appeared {Arch. f. Frotistenkunde, v. 3, IQ04, p. 367), he
regards this flagellate as the type of a new genus Trypanophis, characterized by
a short anterior flagellum and a long flagellum posteriorly ruiming along the
whole length of the body, accompanying an undulating membrane. The centro-
some (or iDlepharoplast), situated quite in front, is much smaller than the nucleus.
Evidently this new genus is closely allied to Trypanoplasma, according to the
modified description we give above.
^ Perhaps the flagellated htematozoon seen by Dutton and Todd in the blood
of mice m the Gambia Colony (see Chapter V.) is neither a Trypanosoma nor a
Trypanoplasma. According to the observers, it had no undulating membrane,
and reminded one of a Herpetomonas. As their observations were made only 011
fresh specimens, it is as well to keep an open mind upon the subject.
" [Woodcock, Quart. Journ. Micr. Sc, v. 50, part ii., 1906, pp. 283-289.]
COMPARATIVE STUDY OF THE TRYPANOSOMES 27
trypanosomes of fresh -water fishes have the flagellum posteriorly situated,
and he puts them in the genus Hamatomonas, created for them by Mitro-
phanov. He does not commit himself upon the trypanosomes of other
vertebrates, and therefore leaves us in doubt as to the morphological
orientation of the type species, T. yotatorium ' (Mesnil).i]
Section 2. — Biology of the Trypanosomes.
The general survey we are making of the trypanosomes would be
incomplete without referring briefly to their behaviour in the blood
or body-fluids of infected animals immediately after leaving the
body and in vitro under different conditions.
Nutrition and Movement. — Trypanosomes derive their nutri-
ment by osmosis. No digestive vacuoles or solid bodies of any kind
are ever seen in them. Trypanosomes displace the red corpuscles
by their movements, but we have never seen them attack the red
corpuscles, either to absorb them or to penetrate into their interior.
Nevertheless, judging from McNeal and Novy's attempts to cultivate
them, haemoglobin seems to be useful, if not indispensable, to them.
[Goebel^ has studied the osmotic properties of T. hrucei by adding a
drop of blood rich in trypanosomes to i c.c. of saline solutions of various
strengths. In strong solutions the trypanosomes are rendered motionless
at once, and lose their virulence, but retain their shape. In isotonic
solutions they remain motile, while in weak solutions they become
deformed and involuted. Trypanosomes immobilized by strong solutions
remain alive for some time (e.g., one hour in a normal solution of NaCl),
and on diluting sufficiently, regain their mobility and virulence.
The action of the saline solutions upon the trypanosomes is almost the
same as on the red corpuscles ; perhaps the latter are a little more sensitive
than the trypanosomes.]
The movements of trypanosomes are due chiefly to the undu-
lating membrane and the free flagellum. When moving sluggishly
in loco one can study in detail the movements of the membrane,
which consist of undulations, first in one direction then in another.
It is possible to make out also that the free flagellum has a lashing
movement, oscillating alternately to the right and left. When the
trj'panosomes move from place to place, with the flagellum foremost,
which is their usual mode of progression, this movement of the
flagellum to right and left can again be distinguished if the parasite
is not moving too quickly. When it is very active, however, one can
see only a darting, arrow-like movement of the whole of the parasite.
Besides these movements of the undulating membrane and
flagellum, there are others due to a contraction of the whole of the
protoplasmic body. This contraction is apparently dependent upon
a kind of myocyte layer, such as has been observed in gregarines
and other Sporozoa, [or upon the somewhat spirally-arranged
myonemes described by Prowazek and others in several of the
trypanosomes.] Finally, there are amceboid movements localized in
' [Mesnil, in Bull. Inst. Past., v. 4, 1906, pp. 793-795']
''■ [Goebel, Ann. Soc. mid. de Ga7id, 1906, p. 1 1 ; abstract by Mesnil, in Bull.
Inst. Past., V. 4, 1906, p. 256.]
28 TRYPANOSOMES AND THE TRYPANOSOMIASES
particular parts of the body especially the posterior part (see section
on Morphology for variations in shape of this part of the body).
One or other movement predominates, according to the species.
Amongst the mammalian trypanosomes it is the flagellar motion,
but this varies in degree in the different species. For example,
T. lewisi easily traverses the field of the microscope with an arrow-
like motion ; trypanosomes of the type brucei hardly move from
the spot where first seen, except T. evansi, which is sometimes seen
to travel across the field of the microscope, but always more slowly
than T. lewisi}
The contractile movements of the protoplasmic body are often
seen in the trypanosomes of fishes — for example, the parasites of the
eel or of the Selachii, which are often contorted and coiled up on
themselves. The trypanoplasms also move about very actively, so
as to resemble a piece of drapery or muslin thrown into a succession
of folds or curves. Lastly, T. rotatorium of frogs exhibits marked
amoeboid movements, consisting mainly of contractions of the ex-
tremities of the body, especially the posterior, with constant changes
of shape.
Infectivity and Virulence. — Trypanosomes develop in the
body of an animal owing to their power of reproduction. By the
pathogenic trypanosomes this power is retained throughout the illness,
but is more or less developed according to the species of animal
infected and the period of the disease. For example, in a horse with
nagana'the trypanosome's power of reproduction coincides with the
febrile attacks. In the case of the non-pathogenic trypanosomes,
the period of multiplication of the parasite is limited to a certain
number of days at the beginning of the infection. Later on only
adult forms of the parasite are seen in the blood and internal organs,
developmental forms being absent.
Even in the case of the non-pathogenic trypanosomes the power
of infection may vary within certain limits. Such is the case, for
example, with T. lewisi, where the variation depends upon both the
origin of the trypanosome and the rats inoculated. We shall see,
moreover, that this species is in certain cases really virulent, the rats
dying from it not showing any more trypanosomes than other rats
which, infected with another strain of parasite, are unaffected thereby.
Apparently, therefore, infectivity and virulence may be independent
of one another.
1 [I have very often seen the human trypanosome, both in human blood and
cerebro-spinal fluid and in the blood of inoculated animals, travel very rapidly, so
that it was with difficulty kept under observation by moving the slide about. The
same rapidity of movement was seen in the case of several animal trypanosomes
found in Uganda. Possibly the difference between my own and the authors'
observations may be due to. the fact that in our laboratory in Uganda the
temperature was generally about 80° F. and the air very moist, and that the
cover-glasses were always ringed with a layer of vaseline at once to prevent
evaporation.
Ziemann has also described, in the blood of cattle in Cameroon, a very active
trypanosome, which, on account of its great activity, he calls T. vivax (See
Chapter VI.)] ^
COMPARATIVE STUDY OF THE TRYPANOSOMES 29
For a given pathogenic trypanosome the virulence varies, first,
with the species of animal inoculated. Every chapter of this book
furnishes so many instances of this that there is no necessity to
insist upon it here. Secondly, it varies with the race of the
mammal ; thus it seems clear that races acclimatized to the countries
where such trypanosomiases are endemic are less susceptible than
corresponding races of unaffected areas — e.g., dogs imported into
South Africa or India, cattle from Madagascar, etc.
Thirdly, it varies with the origin of the trypanosomes, and thus
seems to depend on conditions we are unable to determine accurately.
All the evidence brought forward hitherto^ goes to show that all the
human trypanosomes seen in Africa belong to a single species —
T. gmnbicnse, yet the parasite studied by Brumpt and Wurtz was
clearly more virulent than that from the Gambia studied by Button,
Todd, Annett, and ourselves. The latter was more virulent than
that of Bruce, Nabarro, and Greig from Uganda, and finally Manson,
with a trypanosome from another source (Congo), was unable to
infect any animals.
Fourthly, virulence apparently varies, though only to a slight
extent, with passage through certain definite species of animals.^ To
this undoubtedly must be attributed the different results obtained by
Kanthack, Durham, and Blandford in England, and by ourselves in
France, with the same strain of trypanosome, and with very closely
allied races of mammals. Other instances of this will be found later
on in this volume, and we shall see that Koch and Schilling at one
time thought that a method for vaccinating bovines against T. brucei
might be based upon this diminution of virulence by passage.
Preservation of Trypanosomes in vitro. — Trypanosomes can
be kept alive for a time in the defibrinated or citrated blood of an
infected animal. The addition of physiological saline to defibrinated
blood rather favours the preservation of trypanosomes, while the
addition of ordinary or distilled water brings about their death more
or less rapidly, according to the proportion of water added.
A large number of chemical substances are harmful to trypano-
somes in vilro. A list of them will be given in the account of our
attempts at the treatment of nagana.
Trypanosomes are very sensitive to heat. Few pathogenic
trypanosomes can stand for even a very short time a temperature of
40° C. or above. Exact data will be found in the chapter on
T. brucei. T. lewisi is more resistant to temperatures above 40° C.,
but its sensitiveness is still very marked, and it never lives longer
than twelve hours under those conditions.
Trypanosomes are better able to resist a lowering of temperature.
1 [The only exception is that of PHmmer, to which reference is made in
Chapter XII., but which has not been confirmed by any other observer.]
2 [We shall see later on, however, that the 'genealogy' of a parasite — that is to
say, the number of times it has been passed through animals and the different
species of animal through which it has passed — may have a decided effect upon
the virulence, often resulting in a virus-fixe. (See Chapter VI., part ii.)J
30 TRYPANOSOMES AND THE TRYPANOSOMIASES
This is particularly the case with T. lewisi, which has been kept for
two months at a temperature of 5° to 7° C. This parasite can live
between the extremes of temperature 5° and 40" C. On the other
hand, pathogenic tr\-panosomes do not live for more than five or six
days at 5° C.
Trj'panosomes show a certain amount of resistance to tempera-
tures below zero, but some die very rapidly. The lower the tem-
perature, the more rapidly does death take place. Jvirgens has
shown that T. lewisi kept for two hours at —17° C. is no longer
virulent. Under very similar conditions we have found a few trypano-
somes still motile and highly infectious for the rat.
After a quarter of an hour's exposure to liquid air ( - igi° C), all
the trypanosomes with which we have experimented (various patho-
genic trypanosomes and T. lewisi) were found still virulent. It is true
the large majority had died, and only a very few were found motile.
After an hour and a quarter's exposure (on two occasions) T. lewisi
was still able to infect a rat. Blood containing T. dimorphon was no
longer infectious after an hour's exposure, although motile parasites
were still visible. After twenty-four hours' exposure T. lewisi and
T. dimorphon were all completely destroyed or spherical in shape ;
neither was virulent on inoculation.
Before dying the trj-panosomes undergo various changes of form,
of which the following are the most important : The appearance of
vacuoles in the protoplasm, especially at the centrosomic end,
granular degeneration of the protoplasm, detachment of the flagellum
from the undulating membrane, and conversion of the protoplasmic
body into spherical forms, passing through intermediate stages, such
as tadpole forms, in which a little protoplasm still accompanies the
flagellum. Some of these degenerative stages are seen in vivo, as,
for example, during the last hours of the life of an infected animal ;
also, in a marked degree, in an animal treated with human serum or
with arsenic.
Another very curious phenomenon exhibited by trj'panosomes is
agglutination. But in this case, contrary to what has been observed
in the case of bacteria, agglutination is not preceded by loss of
motility. The results of agglutination are very peculiar : rosettes
composed of a variable number of parasites, all joined together by
their posterior extremities, and with the undulating membranes and
flagella still carrying on their different movements.
These phenomena, which take some time to appear in the case
of trypanosomes kept in the defibrinated blood, occur very rapidly
and to a marked degree on adding to defibrinated or citrated blood
serums obtained from species of animals different from that which
has furnished the trypanosome, or, as in the case of T. lewisi, a
specific serum from the same animal species.
Cultures. — Cultivations of trypanosomes are best made in the
water of condensation in tubes of a solid medium, consisting of
COMPARATIVE STUDY OF THE TRYPANOSOMES 31
nutrient agar, to which is added, when at a temperature of 50° C,
as much defibrinated blood as possible (up to two or three times the
volume of the agar). This method of cultivation has been particu-
larly successful in the case of T. lewisi. Inoculations from one tube
into another succeed, and sometimes give rise to a copious growth,
in which the parasites are typical in appearance. Generally, how-
ever, the culture forms have no undulating membrane, and the
flagellum is inserted in front of the nucleus. The parasites are of
all sizes, from i to 2 /i in length (without flagellum). Some parasites
seem to be able to pass through a Berkefeld filter, for the filtrates of
cultures are infectious.
Results obtained with the pathogenic trypanosomes are much less
satisfactory, and the culture forms, containing as they do numerous
protoplasmic granules, give the impression of being under unfavour-
able conditions.
Cultures do well at 25° C, or even at the ordinary laboratory
temperature. The organisms grow slowly, but remain alive and
virulent for a very long time. At 34° to 37° C. growth takes place
more rapidly, but the cultures die in a few days. Temperatures
above 37° C. are quickly fatal. These facts are analogous to those
which we have noted in connection with the preservation of trypano-
somes in vitro.
Section 3.— Historical Survey of the Genera of Trypanosomes.
Neither Valentin, who discovered the trypanosome of the trout
in 1841, nor Gluge, who discovered that of the frog in 1842, thought
of giving new specific or generic names to these parasites. The
former author simply classes his haematozoon with the Proteus or
AmcehcB of Ehrenberg. Mayer, in July, 1843, gave specific names to
the parasite of the frog {Amceba rotatoria, Paramcecium loricatum
and costatum), but, nevertheless, placed it in two old genera, Atnceba
and Paramcecitim, where it evidently could not remain.
It is therefore undoubtedly Gruby^ who, in November, 1843, was
the first to give a new generic name to the organisms we are study-
ing, and that name, Trypanosoma, should be retained to designate
the trypanosome of the frog (species, sanguinis, Gruby, antedated
by rotatorium, Mayer) as well as the other flagellates, which ought
to be included under the same generic name as the species of Mayer-
Gruby. We have shown in a preceding paragraph that all the
haemoflagellates known up to the present should be so included,
with the exception of the new species of parasite found in fishes, for
which a new generic name is necessary. These points admitted,
we shall inquire into the synonyms of the genus Trypanosoma.
In 1871 Ray Lankester,^ unacquainted with the work of Gruby
and his predecessors, rediscovered the T. rotatorium of the frog and
1 Gruby, C. R. Acad. Sciences, v. 17, November, 1843, p. 1134.
2 Ray Lankester, Quart. Journ. Micr. Sc, v. 11, 1871, p. 387.
32 TRYPANOSOMES AND THE TRYPANOSOMIASES
described it under the name of Undulina ranarum. Undulina is,
therefore, the first synonym of Trypanosoma.
Saville Kent, in vol. i. of his ' Manual of Infusoria ' (1880-1881),
classifies the genus Trypanosoma Gruby with two species : (i) T. san-
guinis of the blood of Rana esculenta and R. temporaria (with Undulina
ranartim Lank, as synonym) ; (2) T. eberihi (n. sp.) for the parasite
of the caecum of birds described by Eberth in 1861.^
In another part of his book Kent creates the genus Herpetomonas
for the form figured by Stein in his ' Infusionthiere ' (part iii., 1878)
under the name of Cercomonas musccE-domesticcE and identified with
the Bodo musccB-domesticce of Burnett and the C. muscarum of Leidy.
The parasite seen by Lewis in the blood of rats in India is included
provisionally by Kent in this new genus Herpetomonas; he calls it
Herpet. lewisi. This inclusion of the flagellate of rats in the genus
Herpetomonas was admitted in 1884 by Biitschli (article ' Protozoa ' in
the work ' Tierreich '), and was retained until recent years, at least
provisionally, by Wasielewski and Senn and by ourselves in our earlier
publications.^ For example, Senn in igoo, in the article dealing
with the Flagellata in the ' Pflanzenfamilien ' of Engler and Prantl,
gives the following differential diagnosis of the two genera Trypano-
soma and Herpetomonas :
Undulating membrane thickened in the form of a flagel-
lum along the outer border, and not reaching to
the posterior extremity of the cell ... ... ... Herpetomonas
Undulating membrane not thickened along the edge,
and running from the anterior to the posterior
extremity of the cell ... ., ... ... ... Trypanosoma
But recent researches have shown that the retention of the genus
Herpetomonas to designate the flagellates of the type lewisi is impos-
sible for two reasons : First, the Herpetomonas muscx-domesticcB, the
type-species of the genus Herpetomonas, from its morphology (whether
one accepts the description of L^ger or the more recent one of
Prowazek) should belong to a genus different from that containing
the flagellate of the blood of rats (constant absence of the undu-
lating membrane in the case of the parasite of the fly, etc.) . Secondly,
the study we made in 1901 ^ of the type-species of the genus Trypano-
soma showed that this species did not differ, in any essential
character having a real generic value, from the species lewisi (it has,
in fact, all the characters which Senn gives to his genus Herpetomonas),
and that there was no reason to classify that species, and all the
allied species, in a new genus different from Trypanosoma.
All the facts discovered since that time, establishing, as they do,
the existence of a series of trypanosomes intermediate in all respects
' Eberth, Zeitschr. f. Wiss.-Zool., v. 11, 1861, p. 98. It is twenty-five years
since Leuckart called attention to the fact, as Stein had already done, that this
supposed trypanosome is probably a Trichomonas. We also agree with this view.
''■ Since then certain authors (Danilewsky, Chalachnikov, Balbiani, Laveran)
have included under the same generic name the parasites of the rat and frog.
^ Laveran and Mesnil, C". R. Soc. Biol., June 22, 1901.
COMPARATIVE STUDY OF THE TRYPANOSOMES 33
between T. rotatorium and T. lewtsi, have confirmed our view, which
has, moreover, been accepted by Senn^ and all competent authorities.
The genus Herpetomonas, with the modified meaning given to it by
Senn, ought to disappear. It should be retained in its original
sense and with its type-species.
In 1882 Grassi,^ while accepting the genus Trypanosoma Gruby,
created a genus Paramoecioides to designate a special parasite of the
blood of Rana esculenta, with undulating membrane, but no free
flagellum. We shall show, when speaking of T. rotatorium, in
agreement with the majority of authors (Butschli, Danilewsky, etc.),
that the form for which Grassi created a new name is a special
form of T. rotatorium. The genus Paramcecioides should therefore
also be considered a synonym of Trypanosoma.
In 1883 Mitrophanov^ introduced a new name — ^the genus
Hamatomonas — for two species of hasmatozoa of fishes with an
undulating membrane and anterior flagellum. The author's
description and drawings show clearly that the organisms in
question were what we understand by the name Trypanosoma (as
opposed to Trypanoplasma).
[It has already been mentioned that Liihe also places the
trypanosomes of fresh-water fishes in the genus Hcematomonas of
Mitrophanov. He has further created the new genus Trypanozoon
for all the mammalian trypanosomes.]
This name Hcematomonas was applied by Crookshank,* in 1886,
to the trypanosomes of Lewis and Evans, but Crookshank only
regarded it as a sub-genus of Trichomonas Donn^, 1837. It is only
necessary to glance at Fig. 2, 5, which represents a Trichomonas, to
be convinced that such a generic assimilation is untenable. No one
else has adopted Crookshank's view.
Of the work of Danilewsky (1885-1889)^ we shall say but little
here. He disregards the Linnean rules of nomenclature and never
troubles about rules of priority. He designates the flagellated
hasmatozoa generally under the name of Trypanosoma, but he
creates names of generic value to designate certain phases in their
development. Thus he calls the flagellated forms of Trypanosoma
without undulating membrane Trypanomonas. We shall find this
name Trypanomonas used by Labbe as a generic term to designate
a parasite from the digestive canal of leeches.
Doflein,^ in his book which appeared in July, 1901, places all
the hsematozoa with undulating membrane in the single genus
Trypanosoma, but he divides it up as follows :
1 Senn, Arch.f. Protistejikunde, v. i, 1902, p. 344.
^ Grassi, Arch. ital. de Biol., v. 2 and 3.
3 Mitrophanov, Biol. Centralbl., v. 3, 1883, p. 35.
* Crookshank, yo«r«. Roy. Micros. Soc, December, 1886, p. 913.
^ Danilewsky, Biol. Centralbl., v. 51, 1885, p. 529, and 'La parasitologic
comparee du sang,' i.,Charkov (1888 in Russian, 1889 in French).
8 Doflein, ' Die Protozoen als Parasiten und Krankheitserreger,' Jena, Fischer,
[901, p. 57.
3
Chief flagellum absent, or very short and
thick ... ... ... ... ... Sub-genus Trypanosoma
34 TRYPANOSOMES AND THE TRYPANOSOMIASES
genus Trypam
{sensti stricio).
genus Trypam
(Danilewsky-Labbe)
Chief
flagellum
present
Undulating membrane prolonged
as a posterior flagellum (two
flagella present) Sub-genus Trypanomonas
No posterior flagellum. Undu-
lating membrane terminating
with the body, or even not
reaching the end of the body Sub-genus Herpetosoma
(new).
The name Herpetosoma replaces Herpetonionas, to which Doflein
restores its original significance. The sub-genera Trypanosoma and
Herpetosoma correspond to the two genera Trypanosoma and Herpeto-
nionas in Senn's classification.
In the sub -genus Trypanosoma Doflein places three species:
Trypanosoma sanguinis Gruby, type-species of the genus, T. eberthi
Kent, and T. balbianii Certes, 1883. We have already stated (see
p. 32, footnote) that T. eberthi was, in all probability, a Trichomonas.
The T. balbianii was discovered by Certes ^ in 1883, and studied anew
by Mobius, Certes himself, and Lustrac. It is found in the digestive
tube and crystalline style of oysters and of other bivalves. These
various authors have described it as a very motile organism, with
undulating membrane along the whole length of the body, but no
free flagellum. We have shown ^ that it was not of the nature of a
flagellated Protozoon, but of a Bacterium. The chromatin substance
is not condensed into a definite nucleus, but scattered throughout
the protoplasm of the body. Moreover, there is, strictly speaking,
no undulating membrane, but rather a loose sheath, in which the
body floats, joined to the body by its two extremities. There is
certainly no thickened edge to the membrane as in Trypanosoma.
[This parasite, which is perhaps a true Spivocheta, and ought to be
called S. balbianii, has recently been closely investigated by Perrin.^ He
describes sexual and ' indifferent ' forms of the parasite, as well as encyst-
ment of the female and indifferent forms. Many of his figures, however,
do not readily suggest the interpretation which Perrin places upon them.
Vies* describes flagella in bunches, but recognises — as, indeed, some of his
figures suggest — that these ' flagella ' may be due to fragmentation of the
membrane.]
Finally, Doflein gives an inexact definition of the Trypanosoma
sanguinis. That definition amended, and the two species eberthi and
balbianii omitted, the sub-genus Trypanosoma of Doflein blends with
his sub-genus Herpetosoma, and, as we have already had occasion to
mention, the creation of these two sub-genera is no longer justified.
As for the sub-genus Trypanomonas, its definition is the same
as, only shorter than, that of the genus Trypanoplasma, which we
created some months later.
1 Certes, Bull. Soc. zool. France, v. 7, 1882, p. 7.
^ Laveran and Mesnil, C. R. Soc. Biol., October 19, 1901.
3 [W. S. Perrin, Proc. Roy. Soc, Series B, v. 76, 1905, pp. 368-375 ; Arch.f.
Protistenkunde, v. 7, 1906, pp. 131-156.]
* [Vies, C. R. Soc. Biol., November 16, 1906, p. 408.]
COMPARATIVE STUDY OF THE TRYPANOSOMES 35
We come next to the creation by ourselves, in October, 1901,1
of a new genus, Trypanoplasma, with the characters we have given
above. We shall now give our justification for this new generic
name.
It is quite probable that organisms answering to the characters of
the genus Trypanoplasma had been previously seen by others. Cha-
lachnikov has described varieties of trypanosomes in fishes (especially
of the carp) with two flagella, anterior and posterior. There was
some doubt about this description of the trypanosome of the carp
until M. Plehn described a trypanoplasm of the carp. There is
little doubt that Plehn saw and described the parasite seen by
Chalachnikov. The latter did not create a special generic name for
his bi-flagellate species. Since then other bi-flagellate trypanosomes
have been described, but we have such scanty details about these
parasites that their existence can hardly be considered as proved.
The trypanosome of the guinea-pig of Kunstler ^ is figured with two
flagella, but the figure is not accompanied by any description.
There were possibly also two flagella — the author is not very explicit
on the point — in a trypanosome found by Labbe ^ in the digestive
tract of leeches which had sucked mammalian blood (from the horse
or ass, Labb6 thinks). Labbe compares this trypanosome with
the forms described by Danilewsky under the name Trypanomonas,
and he calls it Trypanomonas danilewsky i. But we now know that
Trypanomonas is a particular evolution form of certam species of the
genus Trypanosoma which never has two flagella. Hence, even if the
trypanosome of Labbe were really bi-flagellate, it would not be
correct to adopt the generic name Trypanomonas for the bi-flagellate
trypanosomes, as Doflein does. The name Trypanomonas should
disappear from the nomenclature, since, taken in its original sense,
it designates only particular forms of Trypanosoma.
In conclusion, we may say that the existence of parasites with
undulating membrane and two flagella had not been established
before our discovery, in 1901, of the hasmatozoon of the red-eye or
rudd, and, in any case, it was necessary to create a new genus for these
organisms, since no existing name was qualified to designate them.
Section 4.— Position of the Trypanosomes among-st the
Flag-ellates.
The position of the trypanosomes (genera Trypanosoma and
Trypanoplasma) in the classification of animals is still far from being
definitely established. Let us, therefore, give the views of the best
authorities.
In 1880 Saville Kent* made the Trypanosomaia the first order of
1 Laveran and Mesnil, C. R. Acad. Sciences, v. 133, October 29, 1901.
'^ Kunstler, Bull, scientif. France et Helg., v. 31, 1898, p. 206.
2 A. Labbd, Bull. Soc. zool. France, v. 16, 189 1, p. 229.
* Saville Kent, 'A Manual of Infusoria,' v. I, 1880-1881.
3—2
36 TRYPANOSOMES AND THE TRYPANOSOMIASES
the class Flagellata. Thus he gives them an isolated position in his
classification. We may add that this order comprises the single
genus Trypanosoma, and that the parasite of the rat's blood is placed
in the genus Herpetomoiias {vide supya), which forms part of the family
CercomonadincE.
We find almost the same thing in the article ' Protozoa,' by
BiitschHi in the ' Tierreich ' of Bronn. Trypanosoma and Herpeto-
nionas (including the parasite of the rat) are placed correctly in the
same sub-order, Monadina Biitschli ; but Trypanosoma there occurs as
an appendix to the family Rhizomastigina of Saville Kent (flagellates
which emit pseudopodia), whiht Herpetomonas forms part of an allied
family, Cercomonadina (also of Kent).
Danilewsky,^ in 1888, insists upon the affinities of the trypano-
somes, especially in their simple form (without undulating membrane)
Trypanonionas, with the H erpetomonas and Leptomonas of Kent.
Senn,^ in 1900, places the two genera H erpetomonas and Trypano-
soma (with the descriptions given above) side by side in the family
Oicomonadacecs {= Cercomonadina; of Kent), of the order Protomasti-
gincF, the simplest of the Flagellata. This family, characterized by
the presence of a single flagellum, and the absence of a lip-like or
collar-like process of protoplasm at the anterior extremity, is made
up as follows :
/No undulating membrane... Gen. Oicomonas, Leptomonas, "
No ' AncyromonaSjPhyllomonas.
envelope I Undulating membrane ... Gen. Herpetomonas and Try-
y panosoma.
Envelope Gen. CodoncBca and Platy-
theca.
Later, in 1902,* in a review of recent researches upon the
trypanosomes, he admits the identity of Herpetomonas (as he under-
stood it in 1900) and Trypanosoma, and he recognizes the existence
of the new genus Trypanoplasma. But he thinks this genus should
be placed in a family distinct from the Oicomonadacece — namely, the
family Bodonaccs, characterized by two anterior flagella. He adds
that Trypanoplasma is not exactly like any particular member of the
BodonaccB ; it should be placed near Bodo as a genus differentiated
through having acquired a parasitic habit.
In the interval, and before the discovery of the genus Trypano-
plasma, Doflein, in 1901,^ placed the trypanosomes in the order
Protomonadina of Blochmann. He divides the Protomonadina into
three families : (i) Trypanosomidce, comprising the single genus
' Biitschli, Bronn's 'Tierreich,' 'Protozoa,' v. I, fasc. 2, ' Mastigophora,'
pp. 811-813, 1884.
2 Danilewsky, ' La parasitologie comparee du sang,' i., Charkov, 1888 and i88g.
^ G. Senn, 'Die natiirhchen Pflanzenfamilien von Engler und Prantl,' Parts
202 and 203, Leipzig, 1900.
■• Senn, Arch.f. Protistenkunde, v. I, 1902, p. 353.
* Doflein, 'DieProtozoen als Parasiten, etc.,' loc. cit.
COMPARATIVE STUDY OF THE TRYPANOSOMES 37
Trypanosoma ; (2) Cercomonadiniz, with the genus Herpetomonas Kent,
amended Doflein (excluding the parasite of blood of rats) ; and
(3) Bodonidce.
[Minchin^ divides the Flagellata into {a) Choanofiagellata (with
one flagellum and one or two collars at its base) and (b) Lissoflagellata
(flagellum single or multiple, no collar, and sometimes an undulating
membrane). The Lissoflagellata comprise three orders : (i) Monadidea,
(2) Euglenoidina, and (3) Phytoflagellata. All forms of parasitic
Flagellata hitherto known are referred to the first of these orders,
the Monadidea. Minchin gives three sub-orders of this order — namely,
(r) Pantastomina, (2) Protomastigina , and (3) Polymastigina. The
sub-order Protomastigina is the most important from our point of
view, including as it does (i) the genus Trypanosoma and its allies
{Trypanoplasma, and perhaps Trypanophis), grouped together as the
{a.mi\y Trypanosomatidcs ; (2) the gcnas Spirocht;eta a.nd allied forms ;
and (3 and 4) the genera Herpetomonas and Crithidia.]
L6ger, in his publications of 1902 and 1903,^ in which he gives
precise cytological details concerning Herpetomonas and creates a
new genus, Crithidia (body pyriform or like a barleycorn, instead of
fusiform, as in Herpetomonas), also draws attention to the close connec-
tion between these genera and the genus Trypanosoma, based no
longer upon a simple external resemblance, but upon a resemblance
in the cytological details. Moreover, as he has found some of these
forms in the intestine of blood-sucking insects, he has suggested that
they were perhaps stages in an evolutionary cycle in the life-history
of the Trypanosoma.
[During the past few years flagellates of the genera Herpetomonas
and Crithidia have been described by various observers in several
other invertebrates.]
[In 1898 Ross^ found ' amoebulas and flagellulse ' in mosquitoes (Culex
fatigans, and once in Anophelina) in India. Their habitat was chiefly the
intestinal canal of the larva, pupa, and imago, and Ross states that many
of them resembled trypanosomes. Since then the same or a similar
organism has been seen in Anophelina by Chatterjee, Stephens and
Christophers, and by Leger, who has given it the name Crithidia
fasciculata.]
[The Sergents* describe a new flagellate, which they call Herpetomonas
algeriense, from the intestine of many Culex pipiens, and one Stcgomyia
fasciata reared from larvae in their laboratory. Two forms were seen —
elongated motile forms and spherical motionless forms — but they both
differed from Crithidia fasciculata in having the centrosome posterior to the
nucleus. The Sergents also found in the digestive tube of a larva of
Anopheles maculipennis a flagellate closely resembling Herpetomonas jaculum
Leger.]
' [Minchin, article on the 'Parasitic Protozoa,' in AUbutt and Rolleston's
'System of iMedicine,' v. 2, part 2, 1907. I am indebted to Professor Minchin for
allowing me to see the proof-sheets of this article before publication.]
^ L^ger, C. K. Acad. Sciences, March, 1902; C. R. Sac. Biol., April, 1902;
Arch.f. Protistenkunde, v. 2, 1903.
^ [R. ^oss, Journ. Hyg., v. 6, 1906, pp. 101-108.]
■• [Ed. and Et. Sergent, C. R. Soc. Biol.., v. 60, 1906, pp. 291-293.]
38 TRYPANOSOMES AND THE TRYPANOSOMIASES
[Similar parasites have been found in a blow-fly by Prowazek -^ in the
gut of a sheep-louse [Melophagus ovinus) by Pfeiffer ;- in the body-cavity of
the silkworm [Bomhyx mori) by Levaditi ;^ in fleas which had fed on
jerboas harbouring the Hcemogregarina balfouri, by Balfour ;* in the gut of
Stomoxys, in Uganda, by Gray i^ and in the intestine of Tabanus glaucopis
by Leger,^ who has named this parasite Hevpetomonas subulata.]
[Novy, McNeal, and Torrey^ examined over 800 mosquitoes, after
allowing them to feed on rats, guinea-pigs, and pigeons, which were
certainly free from hsematozoa, and found that 15 per cent, had an intes-
tinal flagellate infection. In some cases masses of rosettes, with centrally
disposed flagella, were met with. Different forms of flagellates were
found, the most common being Cnihidia fascicidata, and a species probably
identical with Hevpetomonas subulata. From their researches on the
cultivation of the trypanosomes of birds, Novy and McNeal maintain
that the flagellates (' trypanosomes ') seen in the stomach and digestive
tract of mosquitoes, tsetse-flies, lice, leeches, etc., are ' cultural ' forms in
vivo, corresponding to those obtained in vitro. ^
[Most, if not all, of the parasites above mentioned occur in two
forms : (i) a flagellated monadine form (the body being long and
acicular in most of the Herpetomonas, pyriform in the Crithidia, and
rarely intermediate between these two forms as in Hevpetomonas (or
Crithidia) minuta of Tabanus tevgestinus ; (2) a gregariniform resting
stage, with a rudimentary or no flagellum and two chromatic cor-
puscules, the parasite resembling the Leishman body of kala-azar
and, to some extent, the piroplasms.]
[As has already been mentioned, rosettes of parasites occur in some
cases, and, moreover, in H. subulata, H. bombycis, and in the parasite
of the sheep-louse {Melophagus ovinus), a rudimentary undulating
membrane has been described.]
[We come lastly to the interesting fact that flagellates (trypano-
somes) have been found in the gut of tsetse-flies. This is important
in view of the statements of Gray and Tulloch and of Koch that
ingested mammalian trypanosomes (7". gambiense, T. bvucei) undergo
developmental (? sexual) changes in tsetse-flies. Novy and Minchin,
Gray, and Tulloch, from an extended study of the trypanosomes of
Glossina palpalis (their results are given in detail in Chapter XVIII.),
have come to the conclusion that the trypanosomes found in freshly-
caught tsetse-flies have nothing to do with T. gambiense. Novy^
thinks that they are ' cultural ' forms of harmless non-parasitic
flagellates, corresponding to the equally harmless Hevpetomonas and
Crithidia observed by him in mosquitoes.]
1 [Prowazek, Arb. a. d. kaiserl. Gesund., v. 20, part 3 ; trans, in Journ. Trop.
Med., V. 8.]
^ [Pfeiffer, Zeitschr.f. Hyg. und Infektionskrank., v. 50, 1905, p. 324.]
2 I Levaditi, C. R. Acad. Sciences, v. 141, 1905, p. 631.]
* [Balfour, ' Second Report of the Wellcome Research Laboratories at Khar-
toum,'' 1906, pp. 103-110.]
^ [Gray, Sleeping Sickness Conitn. of the Roy. Soc, Rep. No. 8, 1907, Art. 21,
App. 3, p. 133 ; also Proc. Roy. Soc, Series B, v. 78, 1906, p. 254.]
^ [L^ger, C. R. Soc. Biol., v. 58, 1904, p. 613 ; abstract in Bull. Inst. Past., v. 3,
1905, p. 190.]
' [Novy, McNeal, and Torrty, Journ. Hyg., v. 6, 1906, p. no.]
^ [Novy, yo«^7z. Infect. Dis., v. 3, 1906, pp. 394-411.]
COMPARATIVE STUDY OF THE TRYPANOSOMES 39
Schaudinn^ has also suggested that Trypanosoma is closely
related to both Herpetomonas and Trypanoplasma.
To sum up, all authors are agreed in recognising the connec-
tion between Trypanosoma and the genera without undulating
membrane, such as Herpetomonas of Kent and Crithidia of Leger,
which are nearly all parasitic in the intestine of insects.
Indeed, everything tends to show that this is the correct view.
It is only necessary to compare the figures which Leger gives of
Herpetomonas and Crithidia (two of them are reproduced in Fig. 4,
Fig. 4. — 1-3, Flagellates ;
4-6, Spermatozoa ;
noctildca.
Flagellated Spore of
, Crithidia minuta Leger, from the gut of Tahanus iergestinus (after Leger). 2. Herpeto-
monas jaculum Leger, from the gut of Nepa cinevea (after Leger). 3. Herpetomonas
musccB-iomesticce Burnett (after Prowazek). 4. Immature spermatozoon of Rana
fusca (after Broman). 5. Immature spermatozoon of the snail, Helix pomatia (after
von KorfQ. 6. Adult spermatozoon of Bombinator (after Broman). 7. Flagellated
spore of VortiiKM (after Ishikawa). n, Nucleus ; c, Cj, Cj. centrosomes ; A, supporting
rod ; m, undulating membrane.
I and 2) with those of the developmental or cultural forms of
T. lewisi, to be struck by their great similarity.
The difference in the adult forms consists only in the presence
of an undulating membrane in Trypanosoma and its absence in the
genera studied by Leger. ^ This is to be regarded primarily as a
character of adaptability, and correlated with the parasitic mode of
existence of trypanosomes. It has appeared, doubtless for analogous
reasons, in a group of organisms very different from the trypano-
^ Schaudinn, Ar&. a. d. kaiserl. Gesund., v. 20, 1904, p. 387.
2 [We have seen, however, that a rudimentary undulating membrane has since
been described in certain species of Herpetomonas. This makes the resemblance
of these organisms to Trypanosoma still greater.]
40 TRYPANOSOMES AND THE TRYPANOSOMIASES
somes — that containing Trichomonas. We cannot agree with Kent,
Danilevvsky, and Doflein, who see in it a sufficient reason for
placing Trypanosoma in a separate family, and we adopt the view of
Senn, who regards Trypanosoma as a special genus of the family
Oicomonadince or CercomonadincB.
Amongst all the members of that family, trypanosomes included,
movement takes place with the flagellum foremost. It is, therefore,
natural to suppose that in all of them, including trypanosomes, the
flagellated end is morphologically the anterior end. Recently, how-
ever, it has been suggested by some that the morphologically anterior
end of Trypanosoma is the non-flagellated one.^ That opinion is
based on : (i) a consideration of Trichomonas,"^ in which the un-
dulating membrane appears as a flagellum directed backwards,
its free end being posterior (see Fig. 2, 5 /) ; (2) the fact that in
Herpetomonas, as figured by Leger, the centrosome is close to the
anterior extremity, and that it should be the same in Trypanosoma.
Facts do not lend themselves to such an interpretation. The develop-
ment of T. lewisi shows us, amongst other things, forms identical
with the Herpetomonas of Leger, where the centrosome, at first
situated in front of the nucleus, travels gradually towards the
posterior end of the body, taking along with it the flagellum, which
elongates and at the same time becomes separated laterally from
the body of the parasite, so that it comes at last to be joined to it by
merely a thin ridge — the undulating membrane. There is thus no
evidence of a turning backwards of the flagellum ; and, as it is evident
that the anterior extremity of the Herpetomonas-fovm is likewise the
anterior extremity of the adult form, it must be agreed that it is
always the flagellated end.
[Leger,3 Liihe, and others regard trypanosomes as diphyletic in origin.
Those with a morphologically aiifenor flagellum — recognisable by their
becoming attached or fixed by the flagellated end— would be derived from
a Herpetomonas or Crithidia, by the migration backwards of the centrosome
and the gradual development of the undulating membrane ; whereas
those trypanosomes with a morphologically posterior flagellum — such
parasites becoming fixed by their non-flagellated end — would be derived
from a Tiypanoplasma by the loss of its anterior flagellum. Mesnil* does
not agree with this view, but regards all trypanosomes as having the
flagellum morphologically anterior, and therefore considers the genus
Trypanosoma monophyletic. In support of his view, he states that no
importance can be attached to the pole of fixation, since in the same
species one may find rosettes of trypanosomes with the flagella directed
centripetally, and others with the flagella at the periphery. (See later
under T. lewisi.)]
It remains now to review the genus Trypanoplasma. Senn places
it in Bodonacce; Schaudinn, on the other hand, regards it as closely
1 Samhon, /ourn. Trap. Med., v. 6, July i, 1903, p. 205, note; J. Guiart,
ibid., V. 7, January i, 1904, p. 4. [See also Lilhe, Minchin, and Woodcock, in the'
articles previously quoted.]
2 One can add, in the light of Lager's recent work, ' and of the Trypanoplnsma:
^ [Ldger, C. R. Soc. Biol., v. 58, 1904, pp. 613-617.]
"* [Mesnil, Bull. hist. Past., v. 3, 1905, p. 190.]
COMPARATIVE STUDY OF THE TRYPANOSOMES 41
allied to Trypanosoma. He even regards Trypanoplasma as the most
primitive form of all the hsemoflagellates. The trypanosomes are
derived from it by the atrophy of one of the flagella, and by the
diminution in size of one of the originally equal chromatin masses.^
The genus Trypanophis (see p. 26, footnote 3) would represent one of
the stages in the evolution : one of the flagella is reduced in size, and
the two chromatin masses are no longer equal.
The Trypanosoma noctuce of the owl would represent another
stage : the two chromatin masses are unequal, the one being derived
from the other by heteropolar mitosis; but the smaller mass has
still a true nuclear structure, and is not reduced almost to a dot,
as it is in Trypanosoma. In other respects T. noctuce is a true Try-
panosoma.
As for the genus Herpetomonas, Schaudinn, basing his opinion on
the recent researches of Prowazek,^ who describes two flagella very
close together at the anterior extremity (Fig. 4, j), regards it as
being probably derived from the primitive form Trypanoplasma, by
the approximation of the flagellar apparatus leading to the fusion of
the opposite poles.
The recent researches of Leger^ lead to the conclusion that
Trypanoplasma should be regarded as a Bodo (see the figures of Bodo
lacerta recently published by Prowazek*), of which the flagellum,
directed backwards, is closely applied to the body, just as Tricho-
monas may be looked upon as a Trichomastix with the flagellum
directed backwards and applied to the body.
As to the affinities of Trypanoplasma and Trypanosoma, they appear
to us, in the present state of our knowledge, difficult to define
accurately. The argument of Leger, who looks upon the trypanosomes
as trypanoplasms which have lost their anterior flagellum, and con-
quently as organisms with the flagellum morphologically posterior,
cannot, in our opinion, prevail against that based, on the one hand,
upon the development of T. lewisi {vide supra), and, on the other
hand, upon the comparative morphology of different species of the
genus {e.g., transvaaliense and rotatorium), which leads to the conclu-
sion that the flagellated end is the anterior.
It is thus possible that the relations of Trypanoplasma and
Trypanosoma are not so close as Schaudinn and Leger suppose them
to be, and that the points of similarity are partly of the nature
of adaptability to environment.
In conclusion, the trypanosomes appear to us to be the repre-
sentatives of one of the simplest and most primitive groups of the
flagellates.
We cannot leave this subject without making reference to the
' We have already made this suggestion as to the origin of the centrosome in
trypanosomes. We shall refer to it again later.
^ Prowazek, Arb. a. d. kaiserl. Gesund., v. 20, 1904, p. 440.
^ Leger, C. R. Acad. Sciences, v. 138, March and April, 1904.
4
Prowazek, Arb. a. d. kaiserl. Gesund., v. 21, 1904 (Plate II., Figs. 43-46).
42 TRYPANOSOMES AND THE TRYPANOSOMIASES
recent work of Schaudinni (loc. cit.), in which he regards the trypano-
somes (and also the spirochaetes which, according to him, have
fundamentally the same structure as trypanosomes) ' as forming part
of the developmental cycle of intracorpuscular hsematozoa (Hsemo-
cytozoa). That view is based upon observations made upon two
particular species of intracorpuscular parasites of the little owl
(Athene nodua), which both complete their evolutionary cycle in the
body of the common mosquito, Culex pipiens.
In one species {Trypanosoma noctuce), the ookinete, or product of
fertilization of a female by a male element, is transformed into a
true trypanosome in the stomach of the mosquito. Fig. 5, copied
from Schaudinn, shows the different stages of this transformation,
which is accomplished in the following manner : The nucleus
Fig. 5. — Transformation of an Ookinete of an Intracorpuscular Parasite into
A Trypanosome (after Schaudinn).
divides, by heteropolar mitosis, into A and a (Fig. 5, i) the central
filament of the division spindle persisting. The part a divides in its
turn into a and a" (Fig. 5, 2), the new central filament again per-
sisting. A is the principal nucleus, a the accessory nucleus or
blepharoplast. Finally, a" divides by mitosis, and gives rise to the
whole of the flagellar apparatus (Fig. 5, j, 4., 5). The edge of the
undulating membrane and the free flagellum are the central filament
of the spindle greatly elongated (which explains how it is the flagellum
has a chromatin-staining reaction). The peripheral filaments of the
division spindle also persist.
' [A complete translation of this paper by Schaudinn appeared in the numbers
of the Journ. Trap. Med., June i to November t, 1904. A very full analysis of
it is given by Woodcock in his article in the Quart. JoKrn. Micr. Sc, v. 50. At
the express wish of the authors, I have simply translated what they wrote in
the original of their book, without making any alterations. I have, however, made
some additions to the authors' original short resume. — Ed.]
2 [But Schaudinn afterwards abandoned this view that all spirochsetes would be
found to have fundamentally the same structure as trypanosomes.]
COMPARATIVE STUDY OF THE TRYPANOSOMES 43
In the other species^ there is formed on the surface of the
ookinete a large number of small trypanosoraes (like those repre-
sented in Fig. 6, /, very highly magnified). These trypanosomes
elongate, divide longitudinally (Fig. 6, 2), often forming pairs joined
by their posterior extremities (Fig. 6,j), and in the same straight
line. Thus are produced, says Schaudinn, parasites indistinguishable
from true spirochsetes, having the power when they are in pairs of
moving equally well in either direction, and capable of further sub-
division (Fig. 6, ^andj). They are of all sizes (Fig. 6, 2,j, and (5 to ^),
and some are so small that they are recognisable under the micro-
scope only when agglomerated into rosettes, and one can easily
imagine, says Schaudmn, that they could pass through a Chamber-
land filter.
[In the above brief resume of Schaudinn's paper several interesting
facts have been omitted by Laveran and Mesnil. (A) Trypanosoma nocture. — ■
Fig. 6. — Transition of Trypanosomes into Spirochsetes (after Schaudinn).
(i) When an infected mosquito feeds on an owl, it injects into the blood
of the bird ' male,' young ' female,' or ' indifferent ' forms of the trypano-
some. The male forms rapidly die ; the indifferent forms multiply ; and
the young females mature, the last two passing through alternate intra-
corpuscular and extracorpuscular phases. For six days and nights the
intracorpuscular (Halteridimn) stage in the owl alternates with the extra-
corpuscular or trypanosome stage, the former occurring in the peripheral
blood by day, the latter in the internal organs by night. The ' indifferent '
forms of the parasite are fully developed at the end of this six days'
alternation, but the 'female' forms mature more slowly. (2) Female
gametocytes may multiply by parthenogenesis, and give rise to ' indifferent '
trypanosomes, or to ' male ' or ' female ' forms. To undergo their normal
development, however, the male and female gametocytes must be
swallowed by a mosquito with a meal of blood. Both forms of game-
tocyte contain melanin pigment, which is got rid of during the subse-
quent development of the zygote. (3) Eight slender microgametes (of
complex structure) are formed from the microgametocyte. (4) The female
gametocyte, soon after arriving in the mosquito's stomach, undergoes
' [This parasite of the white corpuscles of the owl has been called SpirochcEta,
or Trypanosoma siemanni (Schaudinn), Hmnamosba ziemanni (Laveran), and
Leucocytozoon ziemanni (Liihe).]
44 TRYPANOSOMES AND THE TRYPANOSOMIASES
nuclear reduction, and becomes a ripe macrogamete. It remains spherical,
but develops no flagellar apparatus, and is fertilized by a microgamete,
with fusion of the two nuclei. When fertilization is complete, the resulting
ookinete may develop in one of three ways : it may become an ' indifferent
or a ' female ' trypanosome, or it may give rise to eight small ' male '
forms. These male trypanosomes soon die off in the stomach of the
mosquito, as they also do in the blood of the owl. The ' indifferent ' and
' female ' forms gradually pass along the gut of the mosquito, and
eventually break through the gut wall, getting into the body-cavity.
Mdst of the trypanosomes eventually reach the proboscis, ready to infect
a bird the next time the mosquito sucks blood ; but some of the parasites
may be carried to the mosquito's ovaries, and so give rise to hereditary
transmission of the infection.]
[(B) Spirochceta ziemanni. — In addition to the spirochaetiform and
trypaniform stages described above, PivoplasmaAAke resting stages — which
resemble the Leishman body of kala-azar — are figured by Schaudinn ;
also very large sexual forms, which after conjugation produce a zygote,
and ultimately, by sporulation, an enormous number of spirochsetes.
These spirochaetes flood the gut and Malpighian tubes of the mosquito,
and multiply by fusion, as shown in Fig. 6.]
These facts are not in agreement with the ordinarily accepted
views, and require confirmation.
According to Schaudinn, trypanosomes or spirochetes represent
the asexual multiplication forms (produced by binary longitudinal
division) of the intracorpuscular ha8matozoa in question, both in
the mosquito and in the bird.
We shall confine ourselves to this resume of Schaudinn's work,
referring the reader to the original memoir for a more complete
account of the facts and of the conclusions drawn from them by the
author.
[Since Schaudinn published his paper giving the remarkable life-
history of these two parasites of Athene noctua, some of his results
and conclusions have received confirmation in certain quarters — '■
notably from the work of the Sergents — but have been severely
criticized by Novy and McNeal, Ross, and others.^ There are two
possible sources of error in the experiments of Schaudinn : (l) Some
of the mosquitoes may have been — and probably were — infected with
intestinal flagellates {Herpetomonas or Crithidia), which, as we have
already seen, frequently occur in species of Culex. After the in-
gestion of the blood of an owl these flagellates, if present in the
mosquito's gut, would multiply. This might lead to the erroneous
conclusion that the parasites found in the mosquito after feeding
were derived from others preserit in the blood of the bird. (2) The
observations of Novy and McNeal, Thiroux, Billet,^ and others show
^ [The following are some of the papers bearing on Schaudinn's work on die
'Alternation of Generations and Change of Host' : Billet, C.R. Soc. Biol., v. 57,
1904, p. i5i ; Brumpt, ibid., v. 57, p. 165, and v. 61, 1906, p. 167; Ed. and Et.
Sergent, ibid., v. 57, p. 164, and v. c.Z, p. 57 — all abstracted by Mesnil in Bull. Inst.
Past, V. 2, 1904, pp. 724, 725; Novy and McNeal, 'On the Trypanosomes of
Huds,' Journ. Inject. Dis., v. 2, 1905, pp. 256-308; also 'Trypanosomes of Mos-
quitoes,' Journ. Hyg., V. 6, 1906, p. no; Ross, ibid., p. 96 ; Tniroux, Ann. Inst.
Past., 1905, pp. 65-83.]
^ [Billet, C. R. Acad. Sciences, October 10, 1904.]
COMPARATIVE STUDY OF THE TRYPANOSOMES 45
that birds, frogs, etc., frequently suffer from a double or even a
multiple infection, as with one or more species of trypanosomes
together with one or more species of Hasmocytozoa. The trypano-
somes, moreover, may be very scanty in the blood, so that only one
or two are found on examining several slides, or they may only be
detected by cultivating the blood ariificially in vitro, or in the gut of
some blood-sucking insect (mosquito, leech). Two conclusions are
possible from these observations : (i) That the flagellates are stages
in the life-cycle of the intracorpuscular parasites, as believed by
Schaudinn and his followers ; or (2) that the flagellates and the
intracorpuscular parasites are quite distinct, and that the animals
harbouring them are suffering from a mixed infection, as believed by
Novy and McNeal, Ross, Thiroux, and their adherents. When such
blood containing both parasites is artificially cultivated or taken up
by an insect and only flagellates are found subsequently, the
absence of Halteridium, Drepanidium, etc., would be due to the fact
that these die off, owing to unfavourable conditions.]
[Novy and McNeal conclude from their observations that
Schaudinn has wrongly interpreted his facts in recognising a genetic
relation between trypanosomes and Cytozoa. They interpret his
results quite differently, and say that ' he has cultivated trypanosomes
in vivo, and has obtained forms which agree fully with those obtained
by us (Novy and McNeal) in artificial culture in vitro.']
[MesniP makes the following remarks in this connection : ' In our
opinion, this is going too far. It is highly probable — and this is, we
know, Schaudinn's opinion — that there are avian trypanosomes which
always occur in the trypanosome form ; similarly, there are Cytozoa
without trypanosome-like stages. But we cannot conclude from
Novy and McNeal's interesting observations that Schaudinn's con-
clusions are incorrect, obtained as they are by the zoological method
and based entirely upon observations made on mosquitoes. There
was no doubt about the transformation of an ookinete into a trypano-
some, the melanin pigment helping to trace the stages in the
evolution ; it cannot be said, therefore, that in this case it is the
trypanosomes from the bird's blood which have grown.']
[The Spirochetes. — These organisms are possibly closely
related to the family of trypanosomes, and may in some cases — as
appears to follow from Schaudinn's observations upon Spirochceta
(Trypanosoma or HcBinamoeba) ziemanni — even be a stage in the life-
cycle of a trypanosome. At first Schaudinn suggested that on care-
ful examination, all spirochastes would be found to be similarly allied
to true trypanosomes. In a later paper^ he recognises, however,
that the ' spirochaetiform ' stage of this parasite of the owl is far
1 [Mesnil, Bull. Inst. Past., v. 3, 1905, pp. 363-367.]
2 [Schaudinn, Deutsche med. Wochenschr, October 19, 1905, p. 1665 ; abstract
by Mesnil in Bull. Inst. Past., v. 3, p. 879.]
46 TRYPANOSOMES AND THE TRYPANOSOMIASES
removed from the true spirochsetes (such as Sp. plicatilis Ehrenberg,
which is the type-species), and that it has only very distant phylo-
genetic relations with them.]
[Numerous ' spiral ' organisms are now known, but there is still
much difference of opinion as to their true nature, especially in the
case of the mammalian parasites. This is due to the fact that some
of them closely resemble the genus Spirillum of Bacteria, and further,
being very slender organisms, it is exceedingly difficult to make out
the details of structure — such as the presence of flagella or of an
undulating membrane — which are relied upon to distinguish between
the genera Spirillum and Spirochcsta. Thus, to take one example, the
organism of relapsing fever, for a long time known as the Spirillum or
7
s "
Fig. 7. — Treponema pallidum and various Spiroch.etes.
I. Treponema pallidum, ordinary or 'indifferent' form. 2, 6, and 7. Stages in division
of ttie Spirochata-torm of Treponema pallidum. 3. Spirochigta refringens. 4. Spiro-
chtBta of ulcerated cancers (note the blunt ends and the undulating membrane).
5. S. plicatilis, the end of a long parasite. 8. Conjugation of the male and female
elements (Trypanosoma-iorra.) . The small clear spaces in these sexual forms are
regarded as representing the nucleus. (1-5, after Schaudinn ; 6-8, after Krzysz-
talowicz and Siedlecki).
SpirochcBta obermeieri, had come to be regarded as a true spirochaste ;
recently, however, Borrel and Zettnow have described flagella in
Sp. obermeieri and in the Sp. gallinarum of fowls, in which case these
organisms should be regarded as Bacteria and not as Protozoa.^
Novy and Knapp,^ in a recent comprehensive paper upon Sp.
ob'ermeieri and allied forms, express this opinion and recognise as a
distinct species, to which they give the name Spirillum duttoni, the
parasite of African tick fever. Breinl and Kinghorn,^ while retaining
the generic name Spirochceta, agree with Novy and Knapp that these
are distinct species, but Koch regards the two organisms as identical.]
1 [Other details of structure, such as the absence of undulating membrane and
of chromatin, point to the same conclusion.]
^ [Novy and Knapp, yo/^rw. Infect. Dis., v. 3, 1906, part iii.]
^ [Breinl and Kinghorn, Liverpool Sch. Trop. Med., Memoir 21, 1906, pp. 1-52,
with full bibliography.]
COMPARATIVE STUDY OF THE TRYPANOSOMES 47
[Fig. 7, 5 shows the end of a Spirochceta plicatilis, the type-species
of the genus. The characteristic features (according to Schaudinn)
of a true spirochsete are exhibited by this organism — blunt ends, no
flagella, presence of undulating membrane. The chromatic sub-
stance extends along the whole length of the body.]
[The most interesting and important of this group of organisms is
the one first described by Schaudinn and Hoffmann ^ in syphilis, and
called by them Spirochceta pallida. A later study of this organism
led Schaudinn to conclude that 5. pallida differs from all the other
spirochsetes studied by him, viz., S. plicatilis, S. refringens (Fig. 7, j),
which often accompanies 5. pallida in scrapings of superficial
syphilitic lesions, the spirochsete of Vincent's angina, the spirochsete
of ulcerated cancers (Fig. 7, /), etc., in that it shows no trace of an
undulating membrane, its transverse section is circular, and it has a
long flagellum at each end. In one case (see Fig. 7, 2) two flagella
were seen at one end, suggesting longitudinal division.]
[All the other spirochsetes (Fig. 7, j to 5) have a well-developed
undulating membrane, the body is flattened, and flagella are entirely
absent. Schaudinn therefore thinks that S. pallida should be
removed from the genus Spirochceta, and has created the new genus
Treponema,^ so that the organism is now known as the Treponema
pallidum. It may be mentioned that Castellani has discovered a
similar parasite in yaws, to which he has given the name Spirochceta
pertenuis.~\
[Treponema pallidum (Fig. 7, /, 2, 6 and 7) is a very delicate, actively
mobile organism, almost transparent in the living condition. It has
a long, slender, corkscrew-like body with pointed ends, and according
to Schaudinn, there is a long slender flagellum at each end. The
length of the organism varies from 4 /i to 14 /Li ; its curves vary from
ten to twenty or more in number. The curves are narrow, sharp,
and corkscrew- like, and are always more numerous than in 5. re-
fringens, in which the curves are less abrupt and are broad and
undulating.]
[To show the Treponema in scrapings of syphilitic lesions, the
films should be fixed in absolute alcohol for ten minutes, or, better, in
osmic acid vapour for a few seconds (Schaudinn), and then stained
by the Giemsa or Borrel-blue method (see Chapter II.).]
[Krzysztalowicz and Siedlecki^* describe trypanosome-like forms (which
they regard as sexual phases) in addition to the ordinary spirochsetiform
parasites, which they say are asexual. The latter divide by longitudinal
fission (Fig. 7, 2 and 6), and frequently the two daughter individuals may
remain attached by one end. Other appearances these authors interpret
as phases of conjugation (Fig. 7, 8). Convinced of the trypanosomal
nature of this parasite, they propose the name Trypanosoma Ms for it. In
1 [Schaudinn and Kofimann, DeufscAe tned. Wochenschr, May 4, 1905, p. 711.]
2 [Spironema was suggested by Vuillemin and adopted by Schaudinn, but was
found to be preoccupied.]
3 [Krzysztalowicz and Siedlecki, Bull. Acad. Sc. Cracovie, November, 1905,
pp. 713728 ; abstract by IVlesnil, in Bull. Inst. Past., v. 4, 1906, p. 204.J
48 TRYPANOSOMES AND THE TRYPANOSOMIASES
the case of such a delicate organism as the Treponema pallidum, one has to
be careful not to mistake adventitious objects, such as shreds of tissue or
fibrin, or fragments of chromatic substance from the nuclei of leucocytes,
for phases of the parasite. As Minchin remarks, these observations
urgently need confirmation.]
[It is an interesting fact that dourine, a trypanosome disease of
horses and mares (see Chapter X.), is also conveyed by coitus, and
that the nervous symptoms seen during life, as well as the micro-
scopic lesions found post-mortem in the nervous system, very closely
resemble those seen in syphilis (Mott).]
[The Leishman-Donovan Body. — This organism, the parasite of
kala-azar, tropical splenomegaly, and cachexial fever, was first
discovered by Leishman in igoo, in smears of the splenic pulp of a
patient who had died of Dum-dum fever. Leishman's first account
was published in 1903^ and since then the parasite has been found
in similar cases in many other parts of India,^in Arabia and Egypt,*
in China,* and in the Sudan^ and other parts of Africa. Similar
organisms have been found in the tropical skin lesion known as
tropical ulcer, Delhi boil, bouton d'Alep, etc.®]
[The parasite is usually intracellular and occurs in greatest
numbers in the spleen, then in the liver, bone-marrow, and the
lymphatic glands. It is much more rarely found in the other organs.
Statham,^ who studied its distribution in the organs very carefully,
could not find the parasite in the blood, urine, faeces, or small
cutaneous ulcers during life. He says the parasite is never free
or inside the red corpuscles, but other observers (Laveran and
Mesnil, Donovan) describe endoglobular as well as free forms — the
latter being possibly liberated by rupture or disintegration of the
cells containing them. Stacham found them in the endothelial cells
of the capillaries, and also in the reticular cells, myelocytes, and
mononuclear and polymorphonuclear leucocytes of the organs pre-
viously mentioned. In the spleen the parasites often occur in very
large cells, ' macrophages ' (see Fig. 8, /), which may contain as
many as 150 or more of these bodies]
[The Leishman-Donovan body is rounded, oval, or pyriform, and
measures 2 /u. to 3'5 fi in length by i'5 fi to 2 /j, in breadth. The
cytoplasm is described as being finely granular and is sometimes
vacuolated. There are two chromatic corpuscules, the larger of
which is more or less spherical and stains faintly, while the smaller
1 [Leishman, Bni. Med. Journ., May 30, 1903, p. 1252.]
2 [Donovan, Lancet, September 10, 1904, and January 21, 1905, giving the
earlier bibliographical references on the subject ; Christophers, Sc. Mem. of the
Govt, of India, Nos. 8, 11, and 15, 1904, 1905 ; James, ibid., Nos. 13 and 19, 1905 ;
Rogers, Brit. Med. Journ., May 28, 1905, p. 1249 ; Discussion at the I5.M.A.
Meeting, Brit. Med. Journ., September 17, 1904, pp. 642-658 and 687, 688.]
^ [Phillips, /oz^rw. Trap. Med., August I, 1904, p. 236.]
* \K.&x-c, Journ. Trop. Med., v. 8, 1905, p. 220.]
•^ [Neave, B7-it. Med. Journ., May 28, 1904, p. 1252.]
" \y* Rabinowitsch and Kempner and Francis failed entirely in their attempts to
infect the guinea-pig. Per cotitra, Musgrave and Clegg state that they succeeded,
like ourselves, in producing with T. lewisi a mild infection, which was transitory
and unaccompanied by any symptoms.
'TRYPANOSOMA LEWIS!' 67
still remaining quite recognisable. Next the centrosome disappears,
for leucocytes containing only the nucleus of a trypanosome are often
to be seen. The appearance of this nucleus, however, shows that it
is undergoing digestion ; some chromatic granules are alone visible,
the nuclear fluid having disappeared, undoubtedly on account of the
destruction of the nuclear membrane. The destruction of trypano-
somes in the guinea-pig is thus brought about by a process of
phagocytosis — the trypanosomes, surrounded while still living and
motile, are digested by the guinea-pig's mononuclear leucocytes.
[McNeali does not agree with the view that phagocytosis plays the
chief part in the final destruction of trypanosomes. He repeated Laveran
and Mesnil's experiment of injecting trypanosomes into the peritoneal
cavity of (immunized) guinea-pigs, but could find no evidence of phago-
cytosis. The parasites became motionless and were gradually ' dissolved,'
like the process of bacteriolysis in Pfeiffer's reaction. McNeal thinks,
therefore, that trypanosomes disappear as the result of the action of
cytolytic (' trypanolytic ') agents, and not by phagocytosis.]
Lingard says that the blood of Indian bandicoots {vide Chapter V.)
containing trypanosomes is infectious for the guinea-pig, parasites
appearing in the blood on the fourth, fifth, sixth, and eighth days
after inoculation. On the other hand, it is not infectious for the
mule, ass, or rabbit. This fact is interesting in view of the almost
identical degree of susceptibility of the guinea-pig to the rat trypano-
some.
Other Animal Species. — All other species of animals appear to
be quite refractory to inoculations with T. lewisi.
It is true that Lingard states that he succeeded in infecting
various species of animals with the rat trypanosome, but he confused
this trypanosome with that of surra, and the horses which he claims
to have infected with the rat trypanosome had simply become
naturally infected with surra. In our opinion we must only take into
account those of his experiments which relate to field-rats {Nesokia
providens). Two of these rats showed parasites in their blood seven
days after inoculation, and the trypanosomes were constantly present
until the death of the animals, which occurred 102 and 168 days
later. In two other Nesokia trypanosomes did not appear in the
blood until after twenty-four and thirty-nine days respectively.
Koch, Rabinowitsch and Kempner, and we ourselves, have tried
to inoculate this trypanosome into different animals, but without
success. Mice (grey and white), field-mice [Mus sylvaticus and Arvi-
cola arvalis), rabbits, dogs, goats, and horses were all experimented
with. Even the hamster, which is often found to be infected with a
trypanosome closely allied to T. lewisi, is refractory.
When the blood of infected rats is inoculated into any of the
above animals, some trypanosomes can be found in the blood of the
1 [McNeal, yoKr«. Infec. Dis., v. i, 1904, pp. 526, 527.)
5—2
68 TRYPANOSOMES AND THE TRYPANOSOMIASES
inoculated animals for twenty-four or forty-eight hours, but they do
not multiply and rapidly disappear.
After injecting blood rich in trypanosomes into the peritoneal
cavity of white mice, we found that the parasites could be recovered
from the abdominal cavity and from the blood after twenty-four
hours. At the end of forty-eight hours, however, they had all
disappeared. That was also found to be the case with monkeys
(Macacus) inoculated in India by Vandyke Carter and Lingard.
The former found some trypanosomes in the blood on the second
and third days, the latter on the third day. After that trypanosomes
could no longer be found.
Section 3. — Study of Trypanosoma lewisi.
Trypanosoma kwisi IN the Body of the Rat. — First we shall
study the parasite as it occurs in the living body : (i) the fully-
developed parasite ; and (2) the multiplication forms.
(i) Adult Form of T. lewisi. — In fresh blood, examined either in
film or hanging-drop preparations, T. lewisi appears as a very
active worm-like body. It is the most motile of all the trypano-
somes. It moves about very actively amongst the red corpuscles,
to which it imparts varied movements without changing their shape
in any way. It is often seen to travel, flagellum foremost, right
across the field of the microscope like an arrow, which is quite
unusual with trypanosomes. When it moves more slowly slight
oscillations of the flagellum to the right and left alternately can be
made out. In preparations which have been made some time the
movements become still slower, and one can then see the wave-like
undulations of the undulating membrane, which occur first in one
direction, then in another.
[Some authors (Rabinowitsch and Kempner, Prowazek) state
that T. lewisi can also move with the flagellum posterior. Prowazek,
in describing the movements of T. lewisi, says : ' In addition to
movements of the body through contractions of the myonemes,
which often cause a slight spiral motion of the body, one observes
also a forward movement of the parasite through the vibrations of
the undulating membrane and flagellum.']
Fine granules can be seen in the protoplasm, and often, towards
the posterior extremity, a very retractile granule corresponding to
the centrosome. The nucleus is not visible.
T. lewisi measures 24 /i to 25 ^n in length, including flagellum, by
about i"5 /x in breadth.
After staining by the eosin-Borrel-blue and tannin method
mentioned in Chapter II., the structure of the parasite is distinctly
seen (Fig. 10, /, and Fig. i of the plate). The protoplasm, which
is stained pale blue, contains the nucleus {a) stained lilac, and a
much smaller chromatic body (6), situated towards the posterior end.
•TRYPANOSOMA LEWISI ' 69
stained a deep violet. Along the free border of the undulating
membrane c is a filament stained lilac, continuous at the one end
with the flagellum d, whilst at the other it leads to the corpuscule
marked b in the figure. The undulating membrane is unstained
except its thickened edge, which is continuous with the flagellup.
The protoplasm often contains fine granules.
The nucleus, usually situated much nearer the anterior than the
posterior extremity, is oval in form. It contains granules staining
more intensely than the general chromatic body of the nucleus.
The centrosome, which is deeply stained, is usually in the middle
of a clear space, at the border of which the flagellum generally ends,
or appears to end. There is no doubt, however, that the flagellum
and centrosome are connected. When trypanosomes break down
without being entirely destroyed (in blood which has been kept for
some time), stained preparations often show altered trypanosomes
reduced to a flagellum and centrosome, representing, so to speak,
the skeleton of the parasite (Fig. 11, 16), and in such cases the
continuity of the flagellum with the centrosome is quite apparent
(Laveran and Mesnil, Francis).
[From a recent study of T. Icwisi, Prowazek'^ concludes that the
structure and life- history of the parasite are much more complicated
than is usually supposed. As Wasielewski and Senn {loc. cit.) had
originally observed, Prowazek confirms the presence of a peripheral
ectoplasmic layer, or 'periplast,' all round the parasite. He also
describes a number (eight) of fine fibrils — myonemes — like those
seen by Schaudinn in T. noctuce, but much more delicate and difficult
to see. The nucleus is very complicated, possessing a reticulum and
karyosome, and with the chromatin concentrated into eight minute
granules or chromosomes ; there is also said to be a filament joining
the nucleus and centrosome.]
■[Prowazek distinguishes three forms of parasites in the blood :
(i) ' indifferent ' forms, with many granules, and the nucleus not
sharply outlined; (2) 'male' forms, smaller than (i), often stain-
ing more deeply, with an elongated nucleus rich in chromatin ;
and (3) ' female ' forms, with a larger and rigid-looking body, and a
reticular pale-staining cytoplasm. He describes also in the blood of
the rat various nuclear changes — ' auto-synthesis ' ot the nuclear
karyosome (division into four, two parts disappearing and the other
two joining up again), and nuclear reduction (Mesnil, in Bull. Inst.
Past.).]
(2) Multiplication Forms of T. lewisi. — Authors are not agreed upon
the manner in which T. lewisi multiplies.^
^ [Prowazek, Ard. a. d. kaiserl. Gestaid., v. 22, 1905 ; abstract by Mesnil in
Bull. Ins/. Past., v. 3, 1905, pp. 551-554.]
2 As has been stated in a preceding paragraph, in order to study multiplica-
tion forms, it is necessary to examine the blood of a rat inoculated four to eight
days previously ; after that time only adult trypanosomes are found in the blood.
This is the condition foimd in most of the sewer rats infected naturally, and,
as a rule, after a sufficient lapse of time multiplication forms are not seen. The
70 TRYPANOSOMES AND THE TRYPANOSOMIASES
According to Danilewsky, two forms of multiplication must be
distinguished — (i) longitudinal division which occurs while the try-
panosome is actively motile ; and (2) multiplication by segmentation.
In the latter mode of division the flagellum and undulating mem-
brane disappear, the parasite becomes spherical, and the nucleus by
repeated subdivision gives rise to a variable number of young forms.
Rabinowitsch and Kempner recognize — (i) longitudinal division,
(2) transverse division, and (3) segmentation ; in the last case the
flagellum and undulating membrane entirely disappear.
Wasielewski and Senn hold that all the processes of division of
trypanosomes are reducible to a longitudinal division, as is the case
with the other flagellates, except that in dividing trypanosomes the
mother cell is always recognizable by being larger than the daughter
cell or cells. The parent cell and the daughter cells may remain
together for some time, forming a kind of rosette. These authors
are somewhat reticent upon the subject of simple multiple segmenta-
tion. They give a figure, however, illustrating multiplication of the
parasite, in which it is impossible to distinguish the parent cell, as
they say can always be done.
The division forms of T. lewisi are very varied, and on first
examining a specimen of blood in which these multiplication forms
are numerous, one can hardly recognise them as such. Very large
forms are seen side by side with very small ones ; some are practically
normal in appearance, others may assume all varieties of shape.
In fresh blood it is easy to make out, by means of these variations
in shape, whether the trypanosomes are multiplying or not ; but it is
only in well-stained preparations that the evolution of these parasites
can be satisfactorily studied. Fresh blood containing dividing forms
reveals the interesting fact that the trypanosomes while dividing
continue to move, only less actively than usual.
On examining a large number of dividing forms in a well-stained
preparation, they are seen to be divisible into two groups — group a,
represented by Fig. 10, 2 to 5 ; group b, by Fig. 10, 6 to 10.
Group a. — A parasite about to divide enlarges in all dimensions —
in length often to 35 ^, in width to three or four times the normal
(Fig. 10, 2). At the same time the nucleus and centrosome enlarge,
the latter becoming elongated, and the root of the flagellum thickens.
Finally, the nucleus and centrosome come to lie close together.
Later on the nucleus and centrosome divide, sometimes the one,
sometimes the other dividing first. With the division of the centro-
some, the thickened base of the flagellum divides (Fig. 10, j).
[McNeal and Prowazek maintain, however, that the original
flagellum never divides, but that the entire flagellar apparatus of the
daughter trypanosome is developed from the new centrosome.]
peritoneal fluid of a rat inoculated intraperitoneally one or two days previously
also contains numerous multiplication forms, but this exudate does not lend itself
to the cytological study of these parasites.
TR YPA NOSOMA LE WISI '
71
The newly-formed flagellum separates from the old one before
the latter has divided in its whole length, so that at this stage there
is a large trypanosome with two nuclei, two centrosomes, and two
flagella, of which one is much longer than the other. The new
flagellum rapidly grows. The protoplasm next divides, giving rise
to a young trypanosome with short flagellum, attached more or less
closely to the parent trypanosome. Before the young parasite is
liberated it may subdivide, and the parent trypanosome may also
give rise to other parasites ; in this way is brought about the rosette-
like arrangement sometimes seen with one large trypanosome and
several smaller ones.
Group b. — The multiplication forms in this group differ from
the preceding in that the parent trypanosome can no longer be
Fig. 10. — Multiplication Forms of T. lewisi.
I. Adult trypanosome : ir, nucleus ; 6, centrosome ; c, undulating membrane ; rf,
flagellum. 2-5. Trypanosomes in process of division ; 5 shows a small parasite
about to separate from its parent cell. 6-8. Other kinds of multiplication forms,
g. A young free parasite. 10. Division of a young form, (Magnified about 1,700
diameters.)
distinguished. These forms were certainly seen by Rabinowitsch
and Kempner, but with the flagella unstained. Wasielewski and Senn
doubt the existence of them without absolutely denying it. [McNeaP
has recently stated that the characteristic feature of this group b
does not exist in reality, and that ' unbroken multiplication rosettes
show the mother cell.' Petrie ^ also thinks that multiplication takes
place in every instance by unequal longitudinal division.] We were
the first to describe .these forms accurately. Rabinowitsch and
Kempner^ have recently confirmed our observations in every detail.
The parasites vary in size and are spherical, ovoid, or irregular
in shape. In the protoplasm is seen a variable number of nuclei
^ [McNeal, /oar«. Infec. Dis.^ v. i, 1904, p. 523.]
2 [Petrie, /(7«r«. Hyg., v. 5, 1905, p. 194.]
^ Rabinowitsch andKempner, Central/)./. Bakfer., I, Orig., v. 34, 1903, p. 804.
72 TRYPANOSOMES AND THE TRYPANOSOMIASES
with centrosomes near them, and, arising from the centrosomes,
small flagella of equal length.
The nuclei may number 2, 4, 8, or 16. The centrosomes may
be twice as numerous as the nuclei, because division of the former
precedes that of the latter.
At first, although the nuclei, centrosomes, and flagella are
multiple, there is no trace of segmentation of the protoplasm
(Fig. 10, 6). Later on the periphery of the parasite becomes
indented (Fig. 10, 7, and Fig. 2 in coloured plate), and finally the
protoplasm divides into as many parts as there are nuclei and
centrosomes (Fig. 10, 8). The nuclei always multiply by simple
division.^
In the parasites undergoing multiplication the flagella are always
seen in well-stained preparations. During the earlier stages of our
researches upon T. lewisi, we often obtained results like those figured
by Rabinowitsch and Kempner in which the flagella had apparently
disappeared. Since we have learnt to stain our preparations better
we never get such forms, the flagella always being visible, and this
is in agreement with what we said above about the motility of
trypanosomes which are undergoing division.
The multiplication forms in group b are evidently derived from
those in group a. When the young trypanosome (Fig. 10, 5) has
separated from the parent form, its nucleus, centrosome, and
flagellum continuing to divide without concomitant division of the
protoplasm, one can easily understand the formation of such forms
as those represented in Fig. 10, 6, 7, and c?. The small forms
(Fig. 10, p and Fig. 3 in the plate), arising from the breaking up of
the rosettes, may further subdivide into two (Fig. 10, 10), thus
accounting for the existence of verj' small forms.
To sum up, the method of multiplication of the rat trypanosome
is always the same : there is always a division of the nucleus,
centrosome, and root of the flagellum,^ but the variations in appear-
ance which result from the simple or repeated subdivision of these
elements and from the early or late segmentation of the protoplasm,
are numerous.
Trypanosoma lewisi in the Guinea-pig — In the guinea-pig T. lewisi
shows certain differences which are probably attributable to a process
of involution. The multiplication forms occurring in the peritoneal
cavity after inoculation are abnormal. They are still more varied
than they are in the rat, very small forms predominating. After
twenty-four or forty-eight hours, the trypanosomes in the peritoneal
fluid and blood show a highly refractile spot, which at first sight,
on account of its constant proximity to the posterior end of the
1 [Wasielewski and Senn, however, have described a form of mitosis in a case
of multiple division of T. lewisi (see footnote, p. 21) ; Prowazek (see p. 69) and
Byloff {loc. cit.) have also described complex nuclear divisions.]
2 [It is possible that the flagellum does not divide (see p. 70).]
'TRYPANOSOMA LEWIS!'
73
body, might be mistaken for the centrosome. In stained prepara-
tions, however, it is easy to see that the centrosome has its usual
appearance, and that by its side there is a rounded, unstained
vacuole corresponding with the refractile spot seen in the living
trypanosome.
Fig. II, // shows a trypanosome seen in the fresh blood of
a guinea-pig: Fig. ii, 12 a stained parasite from the blood of the
same animal.
Differential Characters of Trypanosoma Uwisi. — T. Uwki
differs considerably from the pathogenic trypanosomes of mammals.^
The size is practically the same, but the general appearance is
different. T. lewisi is thinner and more pointed, and its undu-
Fig. II. — T. lewisi in the Guinea-pig. Involution Forms.
II. Trypanosome in the fresh blood of the guinea-pig: v, refractile vacuole.
2. Trypanosome in a stained specimen of guinea-pig's blood: c, centrosome;
V, vacuole. 13 and 14. Stained trypanosomes after being kept for twenty days in the
ice-chest. 15. Deformed trypanosome after nine days in hanging-drop preparation
(blood and serum of fowl). 16. Centrosome and flagellum, remains of a trypano-
some in stained specimen.
lating membrane less folded. It is more active, and may often
be seen to travel across the field of the microscope without
difficulty ; this is rarely seen in the case of the pathogenic trypano-
somes, except with T. evansi.'^
The protoplasm of T. lewisi stains faintly, and never contains
the large and numerous granules so common in the pathogenic
trypanosomes. The nucleus, except in those parasites about to
1 In his recent work Martini {!oc. cit.) has drawn particular attention to these
differences.
2 [I have myself often seen human trypanosomes from cases of ' trypanosome
fever ' and of sleeping sickness, as well as animal trypanosomes from various
diseased mammals in Uganda, very actively motile in fresh specimens of cerebro-
spinal fluid or blood. In fact, it was sometimes difficult to keep the parasites
under observation, so rapidly did they travel across the field of the microscope.
This difference between my own observations in Uganda and those of the authors
is probably to be explained by the fact that, whereas I was able to study the
parasites directly in the blood of the naturally-infected individuals, the trypano-
somes studied by the. authors had been many times passed through experimental
animals. T. vivax (Ziemann) is also very acti^e (see p. 200). — Ed.]
74 TRYPANOSOMES AND THE TRYPANOSOMIASES
undergo multiplication, is not situated in the middle of the parasite,
as it is in the case of the trypanosomes of the type bnicei, but is
always near the anterior end of the body. The posterior extremity
of T. lewisi is usually very pointed, but too much importance must
not be attached to this characteristic. Lastly, the multiplication
forms arc very different.
Rats infected with T. lewisi are just as susceptible to T. brucci or
T. evansi as are healthy control rats, as Koch {op. cit.), Rogers,^ and
we ourselves have shown. In fresh blood-films of doubly infected
rats it is very difficult to distinguish the two species of parasite, but
in stained specimens the diagnosis presents no difficulty.
Sivori and Lecler have repeated the experiment with T. equinum
of mal de caderas with analogous results.
T. lewisi further differs from the pathogenic trypanosomes in
question by the length of time it can be kept alive at low temperatures,
and the relative ease with which it can be cultivated artificially {vide
infra) .
The morphological differentiation of T. lewisi from the non-
pathogenic trypanosomes of small mammals (which probably con-
stitute so many distinct species or, what amounts almost to the same
thing, varieties specially adapted to their particular host) is much
more difficult, and we shall see in the next chapter that the differential
characteristics of T. lewisi and of the trypanosomes of the rabbit
(Petrie), of the Indian squirrel (Donovan), [of the mouse (Thiroux),
and of the bat (Petrie, Sergent)] are not always easy to define.
Preservation of Trypanosoma lewisi. — The time that trypano-
somes can be kept in hanging-drop preparations or in blood pre-
served in sterilized tubes is very variable.
Danilewsky observed living trypanosomes in rat's blood kept for
eight or nine days in a pipette at the room temperature. Young
trypanosomes, he says, can live a little longer, up to ten or twelve
days.
Our own observations, confirmed by Jiirgens, Francis, Musgrave,
and Clegg, have shown that the temperature has a marked influence
upon the length of time T. lewisi can be kept alive.
During the summer trypanosomes kept in the laboratory hardly
ever survived longer than four days. In winter we kept blood con-
taining trypanosomes (mixed with serum from the rat, fowl, or
pigeon) in hanging-drop at the laboratory temperature for eighteen
days. At the end of that time the blood was profoundly altered, but
several active trypanosomes were still visible.
Trypanosomes so kept gradually become granular and their
movements become sluggish. Fig. ii, 75 represents a trypanosome in
a stained preparation made from blood mixed with fowl serum, and
kept for nine days in hanging-drop. Most of the parasites in this
1 L. Rogers, Proc. Roy. Soc, May 4, 1901.
'TRYPANOSOMA LEWI SI' 75
specimen of blood were deformed. In other cases the trypanosomes
assumed characteristic ' tadpole ' forms.
At the temperature of the ice-chest (5° to 7° C. above zero),
T. lewisi can be kept alive for a considerably longer time.^
We have found active trypanosomes in defibrinated blood mixed
with salt solution and kept in the ice-chest for 30, 36, 44, 47, 49, 50,
51, and 52 days. Francis has kept them alive under the same
conditions for 81 days. On coming out of the refrigerator the try-
panosomes are alwa5's sluggish, but become more active as their
temperature rises. The number of living trypanosomes, however,
diminishes in proportion to the length of time they are kept in the
cold, and those which survive are not as active as they were
originally. Examined fresh they are seen to be distinctly granular.
Large granules appear in trypanosomes kept in the cold for a fort-
night or longer. These granules stain like the centrosome, and are
often as large, but their size and distribution vary. Fig. 11, ij and
//, show two trypanosomes stained after being in the refrigerator for
twenty days.
Lastly, agglomeration of the parasites, in twos or more, may
occur after as short a time as two or three days in the ice-chest.
The parasites are always joined by their posterior extremities. In
this way rosettes may be formed, and, as the trypanosomes are still
active, each organism in the rosette continues to move its flagellum
and undulating membrane. The number of free trypanosomes
diminishes the longer they are kept in the cold, but side by side with
the agglomerated parasites one nearly always finds some free ones
even after a month or more. (For the details of agglomeration, see
later.)
Specimens of blood containing trypanosomes kept in the ice-chest
for 44, 47, 51, 52, and 53 days were still virulent, but the incubation
period in rats inoculated with such blood was longer than usual (vide
svipra). The length of time trypanosomes can be thus preserved is
much diminished if the blood is not collected aseptically and if many
bacteria develop in it.
This great vitality of T. lewisi at low temperatures is one of the
most characteristic features of this species. It enables us to distin-
guish it, and, if necessary, to separate it from the pathogenic species
of the type brucei. The effect upon the other non-pathogenic try-
panosomes should be studied. We shall see later that Petrie has
shown that the trypanosome of the rabbit lives for a month in the
ice-chest.
Jiirgens says that these trypanosomes live only two to four days
at 37° C. We have shown that they can withstand a temperature of
41° C. quite well. At 50° C. the motility rapidly diminishes, and at
the end of five minutes no motile trypanosomes can be seen.
Jiirgens has, however, found that they are still infective after being
1 Laveran and Mesnil, C. R. Soc. Biol., October 6 and November 10, 1900.
76 TRYPANOSOMES AND THE TRYPANOSOMIASES
.heated for two hours to 50° C. and then slowly cooled down. They
cannot withstand the same length of exposure to 58° C.
In a general way, one may say that T. lewisi is affected by
temperatures above 40° C, but certainly less so than are the try-
panosomes of the type brncei.
T. lewisi can also withstand low temperatures well. Thus Jurgens
has kept it alive in slide preparations for at least seven days at
a temperature of -5° to -8° C. When he w^armed the blood for
the daily examination he noticed that the trypanosomes, at first
motionless, gradually regained their motility.
The same observer found that blood kept for two hours at
— 17° C. was no longer infective. We have repeated this experi-
ment under almost identical conditions. A tube of citrated rat's
blood was placed for two hours in a mixture of ice and sea-salt, the
temperature varying from -I5'5° to - 18-5° C. At the end of that
time we found on warming the blood that the majority of the try-
panosomes were motionless, but several were still quite active. Half
a c.c. of this blood injected intraperitoneally into a rat produced
a severe infection after an incubation period of six and a half
days.
We may add, finally, that T. lewisi is able to withstand for
a certain time the temperature of liquid air. Some citrated blood,
kept for a quarter of an hour at a temperature of —191° C. — (very
few of the trypanosomes remained active ; the others were, as a rule,
well preserved, but often granular) — infected a rat on injection of
h C.c. intraperitoneally (incubation five days; infection severe). The
same blood cooled to - 191° C. for a quarter of an hour, then warmed
up and again exposed to liquid air for one hour (on microscopical
examination of the blood, one active trypanosome was found after
a long search), infected a rat again after injection of \ c.c. intraperi-
toneally (incubation six days ; infection severe). In blood exposed
to liquid air for twenty-four hours the trypanosomes were all spherical
and the blood was not infective.
Action of Radium. — T. lewisi in hanging-drop was submitted to
the action of radium through the cover-glass and the sheet of mica
which closed the tube containing the radium. Several experiments
showed that it required about twelve hours to render the trypano-
somes motionless. Trypanosomes are, therefore, more sensitive to the
action of radium than are bacteria.
[Russ^ exposed T. lewisi to the action of X rays, but could detect
no change in the parasite under the microscope.]
Cultivation. — Hitherto we have dealt only with the preservation
of T. lewisi. We are now going to show how this trypanosome may be
artificially cultivated. At different times various observers have
claimed to have obtained, either accidentally or otherwise, the
growth in vitro of various trypanosomes. Thus Danilewsky and
^ [V, K. Russ, Arch.f. Hyg.,\. 56, 1906, p. 354.]
'TRYPANOSOMA LEWISr 77
Chalachnikov have described in detail the changes of shape (into
spherical forms with loss of flagella) and the segmentation of the try-
panosomes of birds, Batrachia, and fishes, when preserved in pipettes.
In the case of T. lewisi, Chalachnikov has claimed to have
obtained cultures by inoculating blood containing trypanosomes into
dog's serum. On looking at the author's figures of the culture forms,
there is no doubt that some of them, at any rate, represent agglutina-
tion rosettes.
More recently Jiirgens (loc. cit., p. 286) mentions having seen, in
hanging-drop preparations of rat's blood containing ' young ' trypano-
somes, and kept at 37° C, ' division forms and developmental stages
which were not seen the day before.' But even if we admit that the
author was not the victim of a mistake, we cannot say that the
problem of the cultivation of trypanosomes was solved.
There is now, however, no doubt that the problem is solved,
especially so far as T. lewisi is concerned, by the researches of
McNeal and Novy, which we have been able to repeat.
In the chapter on Technique we stated under what conditions
trypanosomes could be cultivated ; it is unnecessary, therefore, to
refer again to the subject here.
T. lewisi was the first trypanosome to be cultivated. This is
comparatively easily done in the water of condensation of the blood-
agar medium of McNeal and Novy. By inoculating several tubes
with blood from an infected rat, one nearly always succeeds in
obtaining a culture, and subcultures are equally easy to obtain.
According to McNeal and Novy, T. lewisi grows in media con-
taining I part of blood to 5 and even 10 of agar. But it prefers
media rich in blood, the best proportion being apparently 2 of blood
to I of agar. In their earliest experiments these observers generally
used a medium containing i part of blood to 2 of agar.
At the laboratory temperature growth is very slow, especially if
the medium is inoculated with few parasites. 1 At the end of a
certain time one sees, in addition to isolated trypanosomes, rosettes,
which become more and more numerous and are often composed
of a large number of parasites — as many as 1,000. All these
trypanosomes are actively motile. Later on the number of living
trypanosomes diminishes. In the middle of the rosettes numerous
spherical degenerated forms are seen, and finally they all die. This
final stage is reached at the end of a variable time, which may be
several months when the medium has been freshly prepared and
inoculated with few trypanosomes. By modifying the type-medium
we have described, which served for the cultivations in series of
tubes, McNeal and Novy succeeded in keeping trypanosomes alive
in the same tube for as long as 306 days.
The medium in this case was composed of 2 parts of agar, i part
1 [As previously stated (p. 14), Mathis has recently found that growth occurs
more rapidly in media that have been heated for some time to 75° to 100° C]
78 TRYPANOSOMES AND THE TRYPANOSOMIASES
of rat's blood, and i part of a solution containing i per cent, of
glycocoll and i per cent, of sodium asparaginate. After the tube
had been cooled some defibrinated rabbit's blood was added to the
water of condensation. Defibrinated rabbit's blood alone seems to-
be an excellent medium for the growth and preservation of T. lewisi.
Lastly, good results may be obtained by using ordinary sloped agar
tubes, in which some defibrinated blood is added to the water of
condensation.
At the laboratory temperature McNeal and Novy obtained
between May i6, 1902, and May 19, 1903, eleven generations of
cultures, using a medium containing 2 parts of agar to i of de-
fibrinated blood. A little of the growth of the tenth generation,
inoculated intraperitoneally into two rats, infected them after an
incubation period of four days.
[In May, 1904, Novy, McNeal, and Hare^ stated that this culture
had passed through twenty-six generations in two years. After a
year, says McNeal,^ T. lewisi has become so well adapted to its new
conditions of growth that true colonies, white and glistening like
the colonies of bacteria, often appear on the agar. Smedley^ has
subcultivated T. lewisi through nine generations in nine months, and
' the last generation multiplied rapidly and was quite as infective as
the preceding ones.']
At a temperature of 34° to ^'j° C. growth is more rapid — attaining
its maximum in eight to twelve days — but is otherwise similar in all '
respects to that occurring at the room temperature. After fifteen to
twenty days all the parasites are dead. McNeal and Novy attribute
this rapid death to the transformation of the haemoglobin into
haematin, which occurs rapidly at the body temperature.
From December 4, 1902, to May 23, 1903 (170 days), McNeal
and Novy obtained a series of twenty-two subcultures at the body
temperature. It should be added, however, that the seventh and
ninth tubes of the series were grown at the room temperature. The
sixth tube having accidentally been kept at 40° C. for several hours,
its trypanosomes rapidly degenerated, and subcultures made when
this degeneration was noticed would not grow at 35° C, but only at
the room temperature. The eighth tube of the series, incubated at
37° C, did not grow well, and the ninth tube would not grow at all
at that temperature. It was, therefore, necessary to use a tube of the
ninth subculture grown at the room temperature.
These details show clearly how badly cultures of trypanosomes
can withstand temperatures of 37° C. and above.
Trypanosomes from three tubes of the twentieth subculture of
the series were inoculated into rats. One animal developed only
a very mild infection, but the other two showed parasites in the
1 [Novy, McNeal, and Kave,Jciurn.Am^r. Med. Assor., May 28, 1904.]
2 [McNeal, /oa^w. In/ec. Dis., v. i, 1904, pp. 517-543.]
3 [Smed\ey, Jo II r/u Hyg., v. 5, 1905, p. 29.]
TRYPANOSOMA LEWISI'
79
blood after an incubation period of five to six days. The infection
was ver}' severe and both rats died. McNeal and Novy also found
that, of two tubes of the tenth generation grown at the body
temperature, one (containing an alkalized medium) did not produce
an infection in a rat, while the other (containing ordinary medium,
non-alkalized) gave rise to a normal infection. It is impossible to
draw any definite conclusion from these facts, for the rats which
resisted infection may have been naturally immune.
We have given a mild infection to a rat with a culture of the
second generation grown for twenty-two days at 20" C. Two other
rats became severely infected by intraperitoneal inoculation of i drop
of an original culture thirty-five days old, in which for about twelve
days a copious growth of bacteria and various moulds had developed.
' The T. lewisi as found in cultures varies greatly in size. It is
Fig. 12. — CoLTURE Forms of T. lewisi.
not unusual to find minute forms which, not counting the whip
(flagellum), are but i to 2 /t in length. There are others which are
typical in form, but are not much longer than the diameter of a red
corpuscle. While most of the spindle-shaped cells range from le^.fj, to
20 fi in length, some trypanosomes can be found at times which are
50 ,C4 to 60 /n long. The existence of the small form accounts for the
fact that we have repeatedly been able to infect rats with Berkefeld
filtrates of such cultures' {Journ. of Infect. Dis., v. i, p. 27).
By means of its long flagellum the parasite is able to travel with
great rapidity and almost in a straight line.
Cultures of T. lewisi contain numerous colonies of rosettes, com-
posed of hundreds of fusiform parasites, having rather a stiff or rigid
appearance. In these rosettes, contrarily to what is seen in the
agglutination rosettes,^ all the flagella are turned towards the centre.
1 [Most authorities are agreed upon the central arrangement of the flagella in
the culture rosettes. Prowazek, on the other hand, describes rosettes in culture
media with the flagella peripherally situated, and suggests that the centrosomes
secrete, and pass out on to the surface of the body, a viscid substance, which
causes the end of the body to become sticky. McNeal (Journ. Infec. Dis., v. i,
pp. 517-543) has also ascribed rosette formation and agglutination to a stickiness
of the body of the trypanosomes.]
8o TRYPANOSOMES AND THE TRYPANOSOMIASES
In the culture forms the centrosome is on the same side of the
nucleus as the flagellum, instead of at the other end, as in the forms
found in the blood. It is, therefore, nearer the centre of the rosette
than is the nucleus.
Figure 12 gives an idea of the forms met with in cultures,
(i) Free forms, rounded or spindle-shaped. Some (/ to 3) show
undoubted division forms (equal binary division) ; others (6 and 7)
are interesting because, although the centrosome is on the same side
of the nucleus as the flagellum, the latter is joined to the body by a
short undulating membrane. This is an intermediate stage between
the Herpetomonas without undulating membrane and the adult form
seen in the blood, and its existence proves that the undulating mem-
brane is not formed by the attachment to the protoplasmic body of
a flagellum folded backwards. There are all stages between these
different types.
(2) Rosette forms — some (^) of rounded or pear-shaped parasites,
with short flagella ; others (5) of fusiform parasites, with well-
developed flagella. The former appear to be an early stage of the
latter. Indications of division, especially of the centrosome and
flagellum, are numerous in these rosette forms.
[McNeal (loc. cit., p. 528) studied living cultures by making a Ranvier
slide preparation of i loopful of an actively-growing culture with
2 loopfuls of fresh condensation fluid i'rom a blood-agar tube. On
watching small rosettes — say of four or five cells — he found that at
30° C. complete division of a cell took about one hour, and that the cell
may proceed to a second division within about four hours.]
[Smedley (loc. cit., p. 33) states that Laveran and Mesnil's eosin-Borrel-
blue stain gives the best results with cultures ; and that ' Romanowsky's
stain and similar stains deposit masses of precipitate, and fail to bring out
any detail in the organisms.']
Section 4. — Ag-glomeration of Trypanosoina Jeivisi.^
T. lewisi is, of all the trypanosomes, the one which lends itself
best to the study of the phenomena of agglomeration. On account
of the interesting nature of these phenomena, we are devoting to
them here a section, reproduced almost verbatim from our paper
published in igoi.
Under certain conditions T. lewisi forms very characteristic and
regular colonies. The conditions which bring about the formation
of these colonies may be classified under two distinct headings :
I. Agglomeration is produced in defibrinated blood kept for a
shorter or longer time in the refrigerator. In this case the
phenomenon is always partial, and lasts until the death and degene-
ration of the parasites (see Chapter X.).
1 These phenomena, which we were the first to describe in 1900 (C. R. Soc.
Biol; October 6 and November 10, 1900), and in greater detail in 1901 {Ann. Inst.
Past), have since been studied in the case of the rat trypanosome by Jurgens
and Francis.
'TRYPANOSOMA LEWISI' 8i
2. When defibrinated blood or serum ^ containing trypanosomes
is acted upon by the serum of certain animals, and particularly of
rats which have had one or more injections of blood containing the
parasite, a rapid and often complete massing together of the trypano-
somes is observed. Agglomeration may occur in a few minutes.
Sometimes it persists until the death of the parasites ; sometimes the
agglomerated masses break up again. All the phenomena in the
second category have this in common — that they are brought about
by substances which, by analogy with what is known of the aggluti-
nation of bacteria and red corpuscles, may be called agglutinins,
from their behaviour to heat.
Formation and Morphology of the Agglutinates. — To
study in detail the manner in which these masses of trypanosomes are
formed, it is best to select cases in which the various phases occur
very slowly and the agglutination is never very marked, as, for
example, when physiological saline is added to blood containing
trypanosomes.
The first fact to note, and certainly the most important as
underlying all the peculiarities we shall point out, is that the
agglutination of the trypanosomes is not preceded by any loss of
motility. The trypanosomes which agglomerate are as active as those
which remain isolated, either in the same or in control preparations.
Agglomeration always begins in the same way : two trypano-
somes join by their posterior non-flagellated ends ^ (Fig. 13, /). The
area of contact is very small, but suffices to keep together the
two parasites, which form a straight line, and show considerable
activity.^
Generally the process does not end there, but other parasites
come and join the first two, forming a rosette of a variable number of
individuals, all arranged with the posterior ends towards the centre
of the group, the free and active flagella towards the periphery
(Fig. 13, 2). In this way masses of a hundred or more parasites
may be formed, and they are very interesting to watch. Each
trypanosome retains its movements independently, and seems to be
trying to escape from its fetters, which in some cases it succeeds in
doing. Sometimes, especially in the case of cooled blood, there is a
leucocyte or a group of blood-platelets more or less damaged, in the
centre of the agglomerated mass.
1 Francis recommends allowing trypanosome-containing blood to coagulate,
when the parasites pass out into the serum, and one is then not troubled by the red
corpuscles. He took a precaution which we have never found necessary. As the
blood of infected rats often contained an auto-agglutinin (vide infra), Francis
got rid of this by filtration through porcelain and frequent washings with distilled
water. The trypanosomes collected thus on the filter were suspended in a quantity
of liquid equal in volume to that of the original serum. It seems to us that these
operations would greatly alter the character of the trypanosomes.
2 In examining fresh specimens, there may be some doubt as to which ends are
in contact; in stained specimens there is never any doubt. Figs. 13, i and 3, are
reproduced from stained smears.
2 When we study the trypanosome of nagana we shall quote cases in which the
agglutination is reduced to this pairing of the parasites.
6
82 TRYPANOSOMES AND THE TRYPANOSOMIASES
The agglomerated masses are not always so slowly formed.
When due to true agglutinins, one sees a large number of trj-pano-
somes joining together almost immediately to form a mass. In such
cases the trypanosomes approach one another without the least
regard to orientation, and often this stage is so short that there is no
opportunity of watching it. Soon, however, the parasites arrange
themselves in proper position ; all the posterior ends come together,
and produce the rosette formation we have described.
When dealing with highly agglutinating, and especially with
specific, serums, the process may be more complicated. A number
of rosettes become grouped together so as to form enormous secondary
masses (Fig. 13, j), which, by reason of the movements of all their
component elements, scatter the red corpuscles by which they are
surrounded. Such a condition is quite visible to the naked eye in
hanging-drop preparations, as clear areas with a greyish centre on a
red background.
Finally, when agglutination persists, it is seen that the trypano-
somes in the centre of these secondary masses become motionless
and degenerate, those at the periphery alone remaining motile.
The parasites in these masses are often so adherent to one
another that the blood can be spread in thin films without disturbing
the agglomeration. In this wa}^ very pretty stained preparations
may be obtained. We have never seen any morphological changes
in recently agglomerated trypanosomes.
Agglomeration of Dead or Paralyzed Trypanosomes. —
As we have said above, agglomerated trypanosomes usually retain
their motility. What happens with trypanosomes previously ren-
dered motionless ? We have been able to answer this question in
two ways : (i) by killing the parasites with chloroform or formalin;
and (2) by studying the action of several specific serums which in
big doses paralyze the trypanosomes.
If a thick film of blood containing trypanosomes be exposed to
the vapour of chloroform, all the parasites die in from five to fifteen
minutes, and become granular ; their outhnes become less distinct,
so that the parasites are less easily seen. A trace of formalin added
to the blood gives better results : the trypanosomes are well fixed,
and retain their refractile appearance.
Serums which agglutinate living trypanosomes agglutinate dead
ones equally well, and vice versa, but the agglomerations differ from
those we have described above. The individual parasites in them are
disposed without any attempt at regularity.
Thus, in the case of trypanosomes killed by chloroform there are
masses in which the parasites form a network, with meshes more or
less closely interwoven. In the case of formahn-fixed trypanosomes
the masses are very compact, but the parasites show no definite
arrangement in them.
Our paral3-zing serums in big doses do not render the trypano-
'TRYPANOSOMA LEWISI '
83
somes quite motionless, but only considerably less motile. Under
these conditions the masses formed are like those obtained with
Fig. 13. — Agglutination of T, kwisi.
I and 2. From stained specimens. 3. From fresh specimens, i. Two trypanosomes
joined by their posterior extremities. 2. Rosette of trypanosomes (primary agglu-
tination). 3. Colony or mass of rosettes (secondary agglutination).
trypanosomes killed with formalin, when they are often in the
form of sheaves. In small doses these serums do not exert any
5—2
84 TRYPANOSOMES AND THE TRYPANOSOMIASES
paralyzing influence, but still have great agglutinating power. In
such cases rosettes are formed.
We think that all these facts admit of only one interpretation.
The particular form the agglomerate assumes in ordinary cases
depends upon the motility of the trypanosomes. In a colony which
is in process of formation each trypanosome tries to escape flagellurn
foremost ; the condition of equilibrium which results is, therefore,
represented by a rosette, in which all the parasites have their
posterior extremities directed towards the centre and the flagella
towards the periphery.
DisAGGLOMERATioN. — The motility of trypanosomes also accounts
for a curious phenomenon often seen in agglomerated masses of
the parasites, but never seen in bacterial agglutinates.
Trypanosomes agglomerated almost immediately on coming in
contact with a serum may subsequently become free and isolated
again. The secondary masses disaggregate, the rosettes either
completely breaking up or losing a large number of their component
parasites.^ This fact is very confusing when these phenomena are
first studied. It is not brought about by all serums, and with any
particular serum it is more marked with small than with large doses
of the serum. On the other hand, it does not occur unless the
trypanosomes are actively motile. Those parasites which are not
too tightly held succeed in freeing themselves, and one might imagine
that if the motility of the trypanosomes diminished, the phenomenon
of agglutination might reappear. We have, indeed, seen this happen
on several occasions. Disagglomeration may be prevented by putting
the preparations in the refrigerator ; for, as we have shown, under
these conditions the trypanosomes retain their vitality for a long
time, but their activity is diminished. Looked at from another
point of view, it is seen that, if our explanation of disagglomeration
is correct, its intensity should be in inverse ratio to the agglutinating
power of the serum used.
Vitality and Virulence of Agglomerated Trypanosomes.
— We have made a large number of observations on this point,
particularly with specific serums, of which we always carefully
studied the agglomerating properties before using them for prophy-
lactic purposes. For example, we used the same trypanosome-con-
taining blood mixed either with salt solution or with the serum of a
healthy rat. The mixtures were kept in hanging-drop preparations
at the room temperature (15° C), and in tubes plugged with cotton-
wool in the refrigerator.
The agglutinated mixtures always showed living trypanosomes
as long as the ' control ' preparations, and, moreover, these parasites
were just as infective.
There remains one observation to be made in this connection.
1 The observations were made in hanging-drop preparations at about 1 5° C.
'TRYPANOSOMA LEWI SI' 85
We have already stated that, in the case of persistent secondary
agglutination masses, the trypanosomes in the interior of the mass
die very quickly. That, however, is not to be looked upon as an
exception to the general rule. The trypanosomes die as the indirept
result of the agglomeration, because in the interior of the mass they
find the conditions unfavourable for their vital processes. The
survival of the peripheral parasites is in favour of this interpretation.
Let us now inquire into the details of agglomeration as it occurs
in different cases.
Specific Agglutinins. — The serum of normal rats — white or
speckled rats, or sewer rats {Mus decumanus) — does not agglutinate.'^
As a result of successive inoculations with trypanosome-containing
blood, rat's serum acquires agglutinating properties, which become
more marked in proportion to the immunity produced.^ Even after
a single inoculation, there is distinct agglutinative power when the
infection is at an end. The serum of a rat even during the progress
of the infection may agglutinate slightly, sometimes agglutinating
its own trypanosomes, as we shall see later on.
After five to ten intraperitoneal inoculations the rat's serum has
an agglutinating value varying from 5 to 50 — that is to say, it is
necessary to add to a given quantity of defibrinated blood at least
one-fifth or one-fiftieth of its volume of the serum, in order to produce
agglutination of its trypanosomes. Francis records a case in which
the agglutinating value of the serum was 200. When minimal
doses of serum are used, agglutination masses are formed, which
subsequently break up again almost completely. In larger doses
and with highly-agglutinating serums, rnost of the masses remain
agglutinated, and this is always the case when the agglutinating
value of the serum is higher than 10.
With highly agglutinating serums used in quantities of at least
double the minimal dose, secondary agglomeration masses are usually
formed. Lastly, we have already mentioned the case of rats (which
had had more than ten inoculations) whose serum, in a dilution of
I in 20 (it was not tested in higher dilutions), produced persistent
clumps, and in stronger doses had a distinctly paralyzing effect.
One of these rats, which in seven months had been inoculated
thirteen times, had a serum so paralyzing that, with a dilution
of I in 10, rosettes of the agglutinated trypanosomes were no longer
produced.
The paralyzing power of specific serums thus develops very slowly
during immunization, contrary to what occurs with antibacterial
serums, in which the paralyzing power is always associated with the
power of agglutination.
^ We have, moreover, noted that, on adding to defibrinated trypanosome-
containing blood some rat's serum instead of salt solution, the trypanosomes did
not agglutinate when placed in the ice-chest.
^ It is curious that Rabinowitsch and Kempner, who were the first to prepare a
specific serum, state that their serum had no agglutinating power.
86 TRYPANOSOMES AND THE TRYPANOSOMIASES
Specific serums contain a true agglutinin. Heating to 55° to
58° C. for half or three-quarters of an hour does not diminish their
agglutinating value, but the clumps produced by heated serums are,
as a rule, not so marked nor so persistent as with non-heated
serums. Serum heated to 63° to 65° C.^ for half an hour loses its
agglutinating power.
The serum of a guinea-pig which had been inoculated with
trypanosomes on several occasions was slightly agglutinating ; that
of a normal guinea-pig has no agglutinating power whatever.
Agglutinins in Different Normal Serums.' — The serum of
the guinea-pig, white mouse, man, pigeon, or frog has no
agglutinating properties for T. lewisi. That of the sheep, goat, dog,
or rabbit is slightly agglutinating. In order to obtain definite
results it is necessary to use equal volumes of serum and of blood
containing trypanosomes. Even then agglutination is never
complete, and, as a rule, the rosettes contain only few parasites.
With the serum of the rabbit disagglomeration is almost complete
at the end of some hours. The agglomerates are more persistent
with the serum of the sheep or dog, and with the latter secondary
agglomeration masses may even occur.
The serums of the fowl, horse, and, according to Francis, of the
cat, are much more agglutinating than the above-mentioned, their
value being from 2 to 10. One drop mixed with one or even two
drops of blood containing trypanosomes brings about complete
agglomeration of the parasites. The rosettes contain a very large
number of component trypanosomes, and enormous secondary masses
are formed, quite as large as in the case of specific serums. The
only difference is that in the case of these normal serums the
clumps separate again more or less completely. The agglutinin
present in these serums is affected by heat in exactly the same way
as that of specific serums.
There is a certain parallelism between the agglutinating power of
these various serums for the rat's red corpuscles and for trypano-
somes. Thus, of the mammalian serums which have been investi-
gated, that of the horse is the most active in both cases. Fowl's
serum is also very potent, while the pigeon's is inactive. The
agglutinating value is always much higher for the red corpuscles
than for trypanosomes ; thus, the serum of a fowl had an aggluti-
nating value of 20 for red corpuscles, whilst for trypanosomes its
value was only between 4 and 5.
In these different serums trypanosomes, whether agglutinated or
■not, remain alive for a long time. The serum of the fowl and
pigeon appear to us to possess remarkable properties in this respect
(see p. 74).
1 Rat's serum is coagulated at that temperature. It must, therefore, be mixed
with an equal volume of salt solution. After heating, a very opalescent liquid is
obtained.
'TRYPANOSOMA LEWISI' 87
The Agglutinating Power of the Body Fluids of Infected
Rats for their own Trypanosomes. — This phenomenon is par-
ticularly well seen when the peritoneal fluid of actively or passively
immunized rats injected with trypanosomes is examined in hanging-
drop ; but in such cases only small rosettes are formed, which may
be permanent or temporary.
Sometimes, when the blood of a rat is examined during the
course of an infection, the trypanosomes in an ordinary slide pre-
paration show a distinct tendency to arrange themselves into groups,^
occasionally forming definite rosettes, but we have never seen such
clumping persist.'^
Only a small proportion of our rats have at any time shown this
phenomenon. It appears to have been present in all Francis's rats,
and, moreover, the agglutinins must have been very active, for that
observer was able to get stained specimens showing persistent
rosettes. Francis has observed, and we can confirm his observation,
that the appearance of what he calls ' auto-agglutinins ' in the blood
precedes by a few days the ultimate recovery of an infected rat.
The rats of McNeal and Novy also frequently showed the presence
of auto-agglutinins. [McNeal thinks that agglutination and rosette
formation are due to increasing difficulty in division, and to a gradu-
ally increasing stickiness of the body of the trypanosome, and that
these phenomena indicate commencing antagonistic action of the
host.]
In conclusion, the fact which dominates the phenomena of the
agglomeration of trypanosomes, and which gives them so special a
character, is that the trypanosomes remain active.^ From the point
of view of the general conception of the phenomenon of agglutina-
tion, this fact proves that in the case of actively motile organisms
loss of motility does not necessarily precede agglomeration, or, in
other words, that the paralyzing and agglutinating substances are
different. Certain facts suggest the coexistence of these two sub-
stances in the case of motile bacteria, but in the case of trypanosomes
it is distinctly proved.
During immunization the agglutinating power of the serum
appears rapidly, even while the infection lasts ; on the other hand,
the paralyzing power is manifested only by highly immunized animals,
and we shall see subsequently that the preventive power develops
much later.
^ If one were not aware of this phenomenon, one might think it was the first
stage of conjugation. Stassano {Soc. de Biol., January, 1901) has indeed given it
this interpretation.
^ Laveran and Mesnil, Ann. Inst. Past., v. 15, p. 696.
^ Ledoux-Lebard {Ann. Inst. Past., v. 16, 1902) has recorded analogous results
when blood-serum (from the guinea-pig, for example) acts upon Paramcecia.
These Infusoria retain their motility and agglomerate into rosettes, with their
posterior ends towards the centre of the rosette. The Infusoria are kept aggluti-
nated by a viscid substance, which they eliminate.
88 TRYPANOSOMES AND THE TRYPANOSOMIASES
Section 5. — Natural Modes of Infection in Rats.
The natural infection in grey wild rats seems to be conveyed by
means of fleas and lice, which, after sucking the blood of infected
animals, bite healthy animals.
On crushing lice caught on infected rats, we have found, in
well-stained specimens of the stomach contents, absolutely normal
trypanosomes amongst the red blood-corpuscles. [McNeaP has
also found trypanosomes in lice fed on infected animals ; and in one
experiment such lice infected a health}- rat. He was unable to
make out any developmental stages in the lice. Prowazek's^ observa-
tions are very interesting and important, because he was able not
only to distinguish trypanosomes in various stages in the body of a
rat-louse {Hcematopinus spinulosus) , but also to observe the formation
of sexual forms, as will be described more in detail later. From
these experiments of Prowazek it seems to follow that the Hcemato-
pinus is a true alternate or definitive host, and not merely a mechanical
carrier of the parasite. This is the first time that a sexual cycle of
development in a mammalian trypanosome has been observed.]
Sivori and Lecler have found living T. lewisi in fleas. Rabino-
witsch and Kempner did not succeed in finding trypanosomes in fleas
caught on infected rats, but when they crushed some of these insects
in salt solution, and inoculated the mixture into the peritoneal cavity
of healthy rats, an infection occurred in five out of nine cases.
Sivori and Lecler have successfully repeated this experiment.
Rabinowitsch and Kempner have, in addition, made the following
observations :
1. An infected white rat was kept together with healthy rats. At
the end of eleven to fifteen days trypanosomes appeared in the blood
of the healthy animals. (Sivori and Lecler and we ourselves have
confirmed this observation.)
2. About twenty fleas caught on infected rats were placed upon
a healthy rat. At the end of two to three weeks trypanosomes
appeared in its blood.
These experiments tend to show that fleas play a part in the
transmission of T. lewisi analogous to that of the tsetse-fly in the
transmission of nagana. The transmission by fleas and lice, which
are apterous insects, explains why the infection in rats in any
particular locality may be ver}" localized ; for example, the loft in
Ann Arbor where McNeal and Novy found all the rats infected.
Attempts to produce infection by the mouth or stomach have
given negative results with all observers except Francis {vide supra).
It is certain that rats may become infected by eating food mixed
with blood containing trjpanosomes or by devouring infected rats,
but only when there is an abrasion of the muzzle or buccal mucous
1 I McNeal, _/(?«?-?;. Infec. Dis., v. i, 1904, pp. 517-543.]
2 [Prowazek, Ard. a. d. kaiserl. Gesimd., v. 22, 1905.]
'TRYPANOSOMA LEWISI ' 89
membrane. It is impossible to say whether this mode of infection
plays any part under natural conditions.
[In lice which had fed on infected rats Prowazek saw trypanosomes
first in the stomach or fore-gut, in which he succeeded in studying the
peculiar sexual changes, and even, though rarely, saw the actual process
of conjugation and subsequent development. At the second meal the
trypanosomes are forced towards the middle-gut, and later into the hind-
gut, where they accumulate in the region of the Malpighian tubes. The
parasites then get into the blood-stream, and, as in the case of the mosquito
studied by Schaudinn, reach the pharynx. From there they are inocu-
lated into the body of the host the next time the louse bites. Prowazek
only once found trypanosomes in an ovum, so that hereditary transmission
of the infection appears to be exceptional in the louse.]
[' Various forms were observed in the louse, of which the following
appear to be the most interesting : Forms with a chromatic reduction of
Fig. 14. — Sexual and Conjugation Forms of T. lewisi.
I. Male (sexual) form. 2 and 3. Stages in conjugation of T. kwisi. 4. Ookinete
(zygote). (After Prowazek.)
both nucleus and centrosome, each of these dividing twice, so that the
final nucleus has only four chromosomes. Later, the male and female
forms are differentiated. The male forms are smaller and the nucleus
very elongated and band-like. Prowazek was able to observe, though
very rarely, different stages in conjugation. Fig. 14 shows two stages in
conjugation, and the final result — the ookinete with a single nucleus and
no flagellar apparatus — exactly resembling those of the Plasmodiwn or
Hamanioeba. One finds all stages between these zygotes (ookinetes) and
flagellated forms, in which the centrosome is in front of and near the
nucleus, and which in some respects resemble culture forms, but, unlike
the latter, would have a sexual origin. Prowazek maintains that, during
the development of the flagellated forms from the zygotes, the centro-
some is derived from the nucleus of the zygote by heteropolar mitosis, as
was described by Schaudinn in T. noctua.'^]
The parasites do not seem able to pass through the placenta.
When pregnant females are infected trypanosomes are not found in
1 [From Mesnil's abstract of Prowazek's paper, BztU. Inst. Past., v. 3,
PP- 55I-5S4-]
1905,
90 TRYPANOSOMES AND THE TRYPANOSOMIASES
the blood of the foetus. Chaussat had already noted this fact,
which has been confirmed by Lewis, Lingard, Rabinowitsch and
Kempner, and by ourselves.
Section 6.— Active Immunity : its Mode of Production.
In the short paragraph in their report setting forth the differential
characteristics of T. lewisi (which they call T. sanguinis), and of the
parasite of nagana, Kanthack, Durham, and Blandford state that
rats which have had one infection are refractory to a second inocula-
tion. These observers, therefore, deserve the credit of having shown
the existence of an active immunity against a trypanosome. But it
was Rabinowitsch and Kempner who drew particular attention to
the fact and insisted upon its importance. They say that a rat
which has recovered from a first infection never becomes reinfected,
no matter how large a dose of infective blood be injected into the
peritoneum. This was confirmed by us, then by Jurgens and
Francis. There are, however, exceptions to this rule.
Thus, of thirty rats which we carefully studied from this point
of view, only two became reinfected as a result of a second injection
of blood containing trypanosomes. Perhaps we should mention also
the case of a rat which resisted a first inoculation, but became
severely infected (the infection lasting at least two and a half months)
after a second inoculation. Lastlj', one of our rats, which was severely
infected (three and a half months) after an injection of blood mixed
with J c.c. of a slightly active specific serum, developed a mild infec-
tion, lasting about twenty days, after a second inoculation, and a very
severe infection after a fourth inoculation. On the other hand, we
have already referred to two rats which were quite refractory to the
first and all subsequent inoculations (p. 6i).
Francis has also recorded two exceptions to this rule in the case
of the two rats which received their first infection, the one by way of
the stomach (?), the other through the mouth.
These exceptions, however, do not affect the generality of the law
laid down by Rabinowitsch and Kempner. A first infection, even
though it last only two days and there be very few trypanosomes in
the blood, confers an active immunity upon rats.
Are the Young born of Immunized Mothers themselves
Immune ? — A female rat immunized by us had two litters. The sole
survivor of the first litter resisted all inoculations, but the eight young
of the second litter were as susceptible as normal rats. All the young
of two other females were susceptible. Finally, of two offspring of
a fourth immune female, one resisted the first inoculation, but
became severely infected after the second inoculation, whereas the
other was susceptible to the first injection. These facts show that
immunization through the placenta or by lactation is exceptional, if
'TRYPANOSOMA LEWIS!' 91
it occur at all. We also found that the agglutinating substance does
not pass through the placenta.
Francis likewise found, on infecting five pregnant females, that
the young ones, born without a blood infection, had no particular
resistance to subsequent inoculation.
The immunity . of the guinea-pig after a first infection does not
appear to be so easily acquired or so complete as that of the rat.
Thus, of four guinea-pigs two resisted all inoculations subsequent to
the first, the trypanosomes not reappearing in the blood, while the
two others became freshly infected after the third injection. These
observations are, however, too few in number to enable one to draw
any conclusions from them.
The Mode of Production of Active Immunity in Rats. —
What becomes of the trypanosomes injected into the peritoneal
cavity of an immune rat ? Only very rarely do they appear in the
blood, and in such cases they are present in it only for a very short
time and in small numbers. The trypanosomes, therefore, are destroyed
in the peritoneal cavity itself.
It takes a variable time for all the parasites to disappear. In
large rats, which have already received several injections, one hour, or
even less, is often 'sufficient for the complete destruction of all the
trypanosomes contained in i or I c.c. of blood very rich in parasites
(one trypanosome to one to three red corpuscles).
How is this destruction of the parasites effected ? In order to
ascertain this, a little fluid is removed from the peritoneal cavity ot
rats at varying intervals and examined in hanging-drop. It is seen
that all the trypanosomes in the fluid remain motile, normal in
appearance, and isolated until they completely disappear. It is
absolutely necessary to examine the fluid directly it is withdrawn
from the peritoneal cavity, in order to see that the parasites are
unclumped in the fluid, for in a few minutes after removal from the
body small clumps are formed. The body fluids of immunized rats
are agglutinating, but in our experiments this property has always
been only feebly developed (see Section 4).
The peritoneal fluid withdrawn contains many leucocytes, of
which about two-thirds are polymorphonuclear and one-third mono-
nuclear. One is struck by the fact that the trypanosom;es are often
adherent by one of their extremities to a leucocyte. The parasites
are often seen in process of absorption by the leucocytes. The
leucocyte sends out a prolongation shaped like a truncated cone, in
the long axis of which is seen a part (either the anterior or'posterior
end) of the body of a trypanosome. The free part of the parasite
remains quite motile, and, if this be the flagellated end, the flagellum
moves about vigorously. The leucocytes of immunized rats, therefore
(and we have made many control experiments with normal rats with
negative result), engulf living trypanosomes.
These observations, made at the moment that the fluid is removed
92 TRYPANOSOMES AND THE TRYPANOSOMIASES
from the abdominal cavity, may be continued in the hanging-drop
preparations. The engulfment of the trypanosomes goes on uninter-
ruptedly if the slide is placed on a warm stage at 15° to 20° C. under
the microscope, and can be seen after an interval of one to two
hours. At 37° C. the engulfment of a trypanosome is seen to take
place with great rapidity. At first the parasite is simply adherent
to the white corpuscle, and it often happens that the trypanosome
succeeds in getting away again. Sometimes, however, the leucocyte
gains the upper hand ; it sends out processes all round the tr3'pano-
some, which in a few minutes is drawn in towards the centre of the
leucocyte. Here it rapidly loses its characteristic shape, and becomes
mixed up with the more or less granular protoplasm of the leuco-
cyte, so that in a very short time it is indistinguishable (see
Fig. 15. — Engulfment of a Trypanosome by a Leucocyte.
The figure represents various stages in the engulfment of a trypanosome by a leucocyte
in the peritoneal exudate of a rat, four hours after intraperitoneal injection of
infective blood. A. The free part of the trypanosome is still distinctly motile, but
sluggish ; the part already engulfed is less distinct than the rest of the parasite.
B. The same corpuscle at the end of five minutes : the trypanosome is seen merely
as a process of the corpuscle, the nature of which could be easily mistaken if one
had not followed the stages of the engulfment of the parasite. C. The same after
another five minutes : the trypanosome has been completely swallowed up, and the
leucocyte has resumed its normal appearance.
Fig. 15, A to C. which represents successive stages, drawn at in-
tervals of five minutes, in the engulfment of a trypanosome by a
leucocyte). At a temperature of 15° to 20° C. engulfment takes place
in a similar manner, but much more slowly (the stage represented in
Fig. 15, A is very often met with ; the conical process is sometimes
much more elongated).
To sum up, we may say that the engulfment of trypanosomes by
the leucocytes is the only mode of destruction we have seen in cases
of active immunity, and we have no hesitation in saying that this is,
in our opinion, the only method which occurs.^
We wished to find out, by means of stained specimens, how the
trypanosomes were digested by the leucocytes. In this we have not
*■ [McNeal does not agree with this view. (See addition made on p. 69.)]
'TRYPANOSOMA LBWISI ' 93
been so fortunate as with the peritoneal exudate of the guinea-pig.
Probably the destruction of the parasites occurs very rapidly/ for we
have already seen that observations on the absorption of trypano-
somes in vitro show that the parasites rapidly become deformed.
Undoubtedly the protoplasm is rapidly digested, and only the nucleus
and centrosome remain. Inside the leucocytes, especially the mono-
nuclear, chromatic bodies are often seen, frequently a large one
associated with a smaller one, which we think are the remains of
a trypanosome which has been swallowed up.
We have obtained the best results, showing phagocytosis in vitro,
by mixing together in hanging-drop some exudate (obtained by
injecting intraperitoneally some fresh broth twenty-four hours pre-
viously) from an immune rat and blood containing trypanosomes.
On making smears some hours later we have thus observed several
trypanosomes beginning to be engulfed.
The manner in which trypanosomes are engulfed by the leucocytes
of the rat closely resembles the processes described and figured by
Sawtchenko for the incorporation of the spirochsetes of relapsing
fever by the leucocytes of the guinea-pig.^ In that case, however,
the spirochsetes can be seen a long time afterwards in large vacuoles,
especially on staining with methylene blue intra vitam. These
peculiarities can be accounted for by the differences in the structure
of trypanosomes and spirochsetes.
Section 7. — Passive Immunity. Protective Value of the Serum
of Immunized Rats. Attempts at Treatment. The Mode of
Production of Passive Immunity. The Results of Passive
Immunization.
It is to Rabinowitsch and Kempner that we owe the important
discovery that the serum of rats which have received several injec-
tions of infective blood is protective. In their experiments i c.c. of
serum injected into rats, either at the same time as the infective
blood or twenty-four hours before or after, completely protects the
animals from infection, whereas control rats contract a short infection
(four to seven days). The serum of a normal rat, of a rat passively
immunized, of a hamster infected with trypanosomes (of the
hamster), and of a dog, did not show any protective power. The
same is true of emulsions of brain, spleen, liver, and bone-marrow
of rats whose serum was protective. This last observation is inter-
esting, inasmuch as it creates a strong presumption in favour of the
leucocytic origin of the protective substance. We have already seen
that the trypanosomes are destroyed and digested by the leucocytes.
1 On adding methylene blue, or, better still, neutral red, to a hanging-drop,
one is struck by the large number of leucocytic inclusions which are stained ; but
only on two or three occasions have we seen trypanosomes within the leucocytes,
still recognizable by their shape, stain with neutral red.
2 Sawtchenko, 'Archives russes de pathologie et de bacteriologie ' (Podwys-
sotzky), I goo.
94 TRYPANOSOMES AND THE TRYPANOSOMIASES
As to the mode of production of this passive immunity, Rabino-
witsch and Kempner make the very unlikely suggestion of an
antitoxic action. T. lewisi, which is so feebly pathogenic, is certainly
not a parasite one would associate with any toxic action.
We have repeated the experiments of Rabinowitsch and Kempner,
and have confirmed their observation that the serum of rats im-
munized against T. lewisi has protective properties.^ All our experi-
ments were made with young rats of 30 to 125 grammes. With
these rats the infection is always long and severe, and there are three
well-marked stages in the evolution of the parasite. In such cases
one can easily see the effect of the inoculation of a serum upon this
evolution of the parasite, even when it does not entirely stop the
infection.
In our control experiments we used the serum of various animals :
normal rats, sheep, rabbit, horse, and fowl. In most of the experi-
ments the different serums were mixed in the syringe itself with
blood containing trypanosomes, and the mixture was at once injected
into the peritoneal cavity of rats. In doses of o'5 to i"3 c.c. the
various normal serums were unable to prevent an infection from
following the inoculation.
As to the specific serums, their action varied with the rat furnish-
ing the serum, and particularly with the number of injections the
animal had received. Usually the serum of rats, which had been
inoculated at least five times with infective blood, was active in doses
of o'5 c.c. when it was injected intraperitoneally mixed with trypano-
somes. Under those conditions the parasites disappeared from the
abdominal cavity in from a few to forty-eight hours without under-
going any development, and did not appear in the peripheral blood
at all. Our most potent serums were furnished by rats which had
received thirteen and ten injections respectively.
The serum of the former of these rats was active, when mixed with
the virus, in doses of o'l c.c. ; but this was evidently the minimal
dose, for the trypanosomes injected took twenty-four hours to dis-
appear from the peritoneum, and the rat had a very mild blood
infection lasting four days. In doses of \ c.c. the blood infection
was prevented, and the trypanosomes took only four hours to
disappear from the peritoneum.
The Action of Heat upon the Protective Properties of
THE Serum. — Heated for half or three-quarters of an hour to 58° C,
and even to 64° C, the serum still retains its protective power; but
in these cases larger doses must be given, and the destructive action
on the parasites is slower. At temperatures of 58° to 64° C, there-
fore, the serum loses part of its power. When the serum is heated
to 55° to 58° C, its value is reduced to about one half the original,
and on heating to 64° C. it is reduced still more.^
1 Francis states that he has also confirmed the discovery of Rabinowitsch
and Kempner.
2 As we have said previously, the serum, before being heated to 64° C, must
be diluted with an equal volume of salt solution.
'TRYPANOSOMA LEWISI ' 95
Action of the Serum Unmixed with the Virus. — The serum
also acts when it is injected subcutaneously at the same time that the
trypanosomes are injected intraperitoneally ; but in that case, even
though a much larger dose is given, the action is slow, and a mild
blood infection follows. Injected twenty-four hours after the
trypanosomes, the serum can stop an infection already started, pro-
vided it be given in big doses (i c.c), but the trypanosomes do not
disappear at once. Our experiments have also shown that the
serum injected twenty-four hours before the trypanosomes prevents
an infection, but for this purpose it is necessary to use slightly larger
. doses than are used in mixtures of serum and infective blood.
We have also injected the serum intraperitoneally instead of sub-
cutaneously in doses of i c.c, twenty-four and forty-eight hours after
the commencement of an infection. In all cases the blood infection
was cut short, but sometimes there was a subsequent very short
relapse. These cases should be looked upon as instances of cure
rather than of prevention, because the trypanosomes were already
numerous in the blood, and showed abundant signs of multiplication
in the peritoneum, particularly in the forty-eight-hour experiments.
Attempts at Treatment. — We have been less successful in our
attempts to stop an infection in the declared stage. Rabinowitsch
and Kempner have similarly failed, judging by the following sentence
{op. cit., p. 282) : ' In the case of rats whose blood contained many
parasites, serum injected intraperitoneally for a week showed no
antiparasitic properties.'
We have tried the effect of serum by injecting it into rats on the
eighth day after infection (the beginning of the third stage), on the
thirteenth, thirty-fourth, and fifty-first days. On each occasion there
were many trypanosomes in the blood, and in none of the rats did
the infection show any signs of diminution.
Some rats received, in several injections, as much as 4 c.c. of
serum from immunized rats, control rats receiving similar doses of
serum from normal rats. The results were by no means constant. In
some of the animals the number of trypanosomes diminished in the
blood immediately after the injection, and the parasites disappeared
in a few days. In others a transitory diminution in the number of
trypanosomes occurred, and in fresh specimens the movements were
seen to be sluggish, with an occasional tendency to agglutination.
Lastly, in half of the rats treated we could not detect any antiparasitic
action even on injecting 4 c.c. of serum from immunized rats in some
cases. The serum of normal rats never had any effect.
The serum, therefore, has a slight action in some cases, but this
beneficial effect is not by any means constant, nor is it rapidly pro-
duced.
We have tried, but unsuccessfully, to treat our rats with sodium
arsenite, trypanred, and human serum, which all have a decided effect
upon the animal trypanosomiases.
96 TRYPANOSOMES AND THE TRYPANOSOMIASES
The Mode of Production of Passive Immunity. — We have
seen in Section 4 that in vitro a specific serum is always agglutinat-
ing, rarely paralyzing, and never microbicidal. As a rule, the
agglutinating and preventive properties of a serum develop pari passu.
Our paralyzing serums had the greatest protective powers.
Do these agglutinating and protective properties play any part in
passive immunity ? This is, a priori, hardly likely when the follow-
ing facts are borne in mind : (i) Heat affects these properties
differently ; the agglutinating power is not appreciably altered at
temperatures below 58° C, but has completely disappeared at 64° C,
whereas the protective power, though reduced one half at 58° C,
is not entirely lost at 64° C. (2) Highly agglutinating serums of
normal animals (fowl, horse) have no protective power, whereas a
specific serum, heated to 64° C, whereby it is deprived of all its
agglutinating properties, is still protective.
A close study of what happens in the peritoneal cavity proves
that passive immunity is not humoral in origin, but cellular. On
removing a little of the peritoneal fluid at varying intervals, from
immediately after the injection until the complete disappearance of
the parasites, and examining it in hanging-drop and stained pre-
parations, the following changes are seen :
The trypanosomes in the peritoneal cavity always remain very
active ; they are never motionless, and do not appear altered at all.
The only thing noticed in hanging-drop preparations is slight agglu-
tination of the parasites, which is not surprising seeing that the
serum injected is highly agglutinating. This agglutination which is
seen to occur under the microscope is not to be compared with that
described in Section 4, and, moreover, it is always incomplete.
Lastly, it occurs quite as markedly in the exudate of rats injected with
certain normal serums which have no protective power, such as the
serum of the sheep. Agglutination can, therefore, play only an un-
important part in the protection of the body from trypanosomes.
It is not uncommon to find, on first examining a hanging-drop
preparation, that the majority of the trypanosomes, though very
active, are closely associated with the leucocytes, and that some are
in process of being engulfed by them. On examining the prepara-
tion for some time, all the stages of the engulfment of a very active
trypaiiosome by a phagocyte may be observed. The details of the
process are identical with those we have already described in con-
nection with active immunity.
Stained specimens are less instructive. As in the case of active
immunity, the trypanosomes are destroyed very rapidly, and only
the chromatic remnants — very numerous, it is true — are seen in the
mononuclear and, less frequently, in the polymorphonuclear leuco-
cytes in the exudate. ^ Passive immunity is, therefore, phagocytic
1 This contains two-thirds polymorphonuclears and one-third mononuclears.
'TRYPANOSOMA LEWISI' 97
in origin. In active immunity, as in passive, there appears to be a
stimulation of the leucocytes.
Results of Passive Immunization. — Are rats which resist
inoculation as a result of the action of a prophylactic serum really
immune ? We have inoculated all our passively immunized rats
during the second week after ' immunization.' About one half of
them were refractory ; the others became infected, but the infection
was always mild and of short duration. Moreover, we have noted
in the majority of these rats that, in hanging-drop or ordinary fresh
preparations of the blood, the trypanosomes show a distinct tendency
to agglutination, sometimes forming small rosettes. We have already
referred to this. It follows, therefore, that the agglutinating sub-
stance inoculated persists longer in the body-fluids of the rat than
does the preventive substance. This phenomenon is not absolutely
distinctive of rats passively immunized ; we have seen it, though
very rarely, in rats which have never received any serum, but
Francis states that he has seen it constantly in such cases.
We may add that the rats which were refractory to a second
inoculation had nearly always contracted a mild infection after the
first inoculation with infective blood, plus prophylactic serum.
CHAPTER V
RODENTIA
DIFFERENT TRYPANOSOMES OF SMALL MAMMALS
There are a certain number of trypanosomes parasitic in the blood
of various mammals, and apparently not pathogenic. The best
known of them resemble T. lewisi — (i) in structure ; (2) in that, as
with T. lewisi in rats naturally infected, one does not as a rule find
multiplication forms in the blood ; and (3) in that these trypano-
somes can develop only in a single species or in a small number
of allied species of animals.
Such trypanosomes have been met with in the following species
of mammals :
/Field-mouse (Gros, 1845).!
Mouse (Button and Todd, Gambia, 1903 [P];^ [Thiroux,,
Senegal, 1905; Pricolo,Rome; Kendall, Panama, 1 906] )., .
[Bandicoot (Lingard)].
Rabbit (Jolyetand de Nabias, 1881 ; Nicolle; Petrie, 1904;
[Codergue, Spain ; Bosc, France, 1904 ; Manca, Sar-
dinia ; Bettencourt and Fran9a, Portugal, 1906]).
Guinea-pig (Kunstler, 1883).
Hamster (von Wittich, 1881 ; Koch, 1881 ; Chalachnikov,
1888; Rabinowitsch and Kempner, 1899).
Spermophile (Chalachnikov, 1888).
Indian squirrel {Sciurus palmanmi) (Donovan).
Dormouse {Myoxus avellanarius) (Galli-Valerio, 1903).
,, [{Myoxus glis) {Bmra-Yii, 1905)].
■Miniopterus schreibersii (Dionisi, 1899).
Species from the Roman Campagna (Sambon; Testi, 1902).
Phyllostoma (sp. ?) of Brazil (Durham, 1902) [P].^
Ptenpus mediiis of India (Donovan).
[Myotis mufimts (Sergent, Algeria and Tunis, 1904).
VespeHilio kuldi (Seigent, Algeria and Tunis, 1904 ; Nicolle
and Comte, 1906).
Vespeftilio noctula (Battaglia, Italy, 1904).
Vespevtilio nattereri (Bettencourt and Fran9a, Portugal, 1905).
Vesperugo pipistrelhis (Bettencourt and Fran9a, Portugal,
1905 ; Kisskalt, Giessen, 1905).
Vespenigo serotinus (Bettencourt and Franca, Portugal, 1905).
y.Pipi$trellus pipistrellus (Petrie, 1904)].
Insectivora — Mole (Gros, 1845 ; [Petrie, 1904 ; Thomson, 1906]).
[Carnivora — Badger (Bettencourt and Franca, Portugal, 1905).*]
^ Gros, Bz/iL Sac. Naiiir., Moscow, First Series, v. 18, 1845, p. 423. Gros
writes as follows: 'The blood of a field-mouse showed worm-like bodies which
were so numerous that the red corpuscles appeared endowed with movement.
The parasites were so small as to be hardly recognizable when magnified
400 diameters. The blood of moles often presents the same appearance.'
These parasites have not been seen since.
^ [It is not quite certain whether the flagellate seen by Button and Todd was a
trypanosome or not,]
•* [There is some doubt about this observation. See later.]
* Finally, Ziemann (Arc/i. f. Schiffs u. Tropenhyg., v. 6, No. 10, October,
98
Cheiroptera
DIFFERENT TRYPANOSOMES OF SMALL MAMMALS 99
Section 1. — Trypanosome of the Mouse.
[T. duttoni, Thiroux.]
Whereas rats in different parts of the world are so frequently
infected with trypanosomes, mice appeared until recently to be quite
free from these hsematozoa. The discovery recently made by
Dutton and Todd of a flagellate in the blood of mice (species ?)
found in houses on MacCarthy Island, in the River Gambia/ is all the
more interesting on this account.
This flagellate, however, cannot be a trypanosome, or, to be more
exact, a species of the genus Trypanosoma.
Unfortunately, it has hitherto only been studied in the living condition.
It has the form of a long spindle with rounded ends, the thinner end
having attached to it a flagellum a little longer than the body. Its
discoverers could not see any trace of an undulating membrane. The flagellum
is the only organ of locomotion the animal possesses, as one can easily
verify by "watching the movements of these parasites in a blood pre-
paration. This flagellum acts chiefly as a propelling organ, but at the
same time, by its whip-like movements, it pushes aside the red corpuscles
or other solid bodies which might get in the way of the body of the
parasite, which it drags after it.
The body is 20-8 /x long by 3-2 /x in greatest width. At about 5 /x from
the anterior extremity there is a very retractile spot from which the
flagellum starts. Other retractile granules exist in the anterior half of the
body. The body is flexible, and often takes the form of the letter S.
Of fourteen mice examined, three showed the parasite in their blood
but always in very small numbers, and the animals were apparently not
ill. Field-mice in the same locality were free from infection (twenty
examined).
A rat inoculated with infective blood remained free from infection.
' This parasite,' Dutton and Todd conclude, ' closely resembles Her-
peiotnonas (Leptomonas) bi/tschtii (Kent). The published figures of this
organism very closely resemble our flagellate, except that in the latter the
non-flagellate end is not so conical in shape.' H erpetomonas bhtschlii
inhabits the gut of a nematode (Trilohus gracilis).
[Thiroux- was the first to describe a true trypanosome in the
blood of the domestic mouse [Mus musculus), and the following
account is taken from Thiroux's paper. This trypanosome was
found in one out of thirt)--three domestic mice [M. niiisculus)
caught in St. Louis (Senegal). Morphologicalh', it closely resembles
the trypanosomes of other small mammals — rat, rabbit, and
squirrel.]
1902) has seen trypanosomes (in very small numbers) in the blood of a chimpanzee
in the French Congo, resembling in appearance the 'stumpy' form (preparatory
to division) of T. lewisi, with this difference, that the free flagellum was a
quarter as long again. The undulating memhrane was very easily seen. The
after-history of the chimpanzee was not followed. Perhaps this was the human
trypanosome of Dutton.
"■ Dutton and Todd, 'Trypanosomiasis Expedition to Senegambia,' yo/mj-Zcwz
and Thompson Yates Labor. Reports, v. 5, 1903, pp. 56, 57.
2 [Ttiiroux, Ann. hist. Past., v. 19, 1905, pp. 564-,572.j
7—2
100 TRYPANOSOMES AND THE TRYPANOSOMIASES
[Morphology. — Examined in the living condition, T. duttoni is
seen to be very actively motile, always moving flagellum foremost,
and often getting out of the field of the microscope. When its
movements become more sluggish an undulating membrane is visible.
When stained, its total length is 25 /x to 30 jx, width 2-5 fi. The
centrosome is fairly large, stains a deep violet by the Borrel-blue
method, and is 5 /a from the posterior end. The nucleus is 3'3 /u.
long by t6 /ti to 2 /x broad, stains well, and is 6 /i to 8 /x from the
centrosome. There are sometimes fine chromatic granules in the
protoplasm in the posterior half of the body. Anteriorly the body
appears to end abruptly about 3"3 /x from the nucleus, but on careful
inspection the protoplasm is seen to be prolonged along the flagellum
for a variable distance, which may be as much as 5"6 /u. The free
flagellum measures 6"6 a to 10 fx, and there is a thin undulating
membrane starting from the centrosome.]
[Multiplication. — Multiplication forms are seen only in animals
that are severely infected. Parasites showing binary longitudinal
fission are then not uncommon, and all stages of division may be
seen. Rarely multiple division forms with several nuclei and flagella
may be met with. The division forms of T. duttoni seen in the
blood of mice closely resemble those seen in rats infected with
T. lewisi.']
[Cultures. — In a special medium (a slight modification of that
of Novy and McNeal), containing i part of bouillon-peptone agar to
2 parts defibrinated rabbit's blood, ^ Thiroux succeeded in growing
T. duttoni artificially at 25° to 26° C. Growth was slow in the first
three generations, taking ten to fifteen days, but the fourth generation
showed definite signs of growth on the fourth day. The parasite
evidently takes some time to become accustomed to the altered
conditions, as Thiroux had previously found to be the case with
cultures of T. paddm.']
[The trypanosomes develop in zooglceal masses (of rosettes or colonies),
which usually float on the surface of the water of condensation. Growth
is scanty in the earlier cultures, but in the later ones these masses are
much more numerous, and colonies of the parasite, resembling those of
B. coli, may even develop on the agar itself. The parasites seen in cultures
are slightly smaller than in the blood. They vary much in shape — round,
oval or pyriform, and fusiform. Thiroux does not agree with Novy and
McNeal in thinking that these different forms are sexually different, for
all intermediate stages are seen. On staining, it is seen that the centro-
some is anterior to or at the side of the nucleus, and that there is no
undulating membrane. T. duttoni thus resembles T. lewisi in giving rise
to Herpetomonas-ioTtns in culture. Reproduction takes place by binary
fission or by division into three, but the commonest is multiple division,
which gives rise to pretty rosette forms. As in cultures of T. lewisi, the
flagella are always directed towards the centre of the rosette.]
[Inoculation Experiments. — T. duttoni is inoculable into
domestic mice (M. musculus), white mice, and harvest mice
' [For details of the preparation of this medium, see Thiroux's paper, loc. at.,
pp. 566, 567.]
DIFFERENT TRYPANOSOMES OF SMALL MAMMALS loi
(M. minutus). The incubation period is four to nine days, and the
infection lasts two to four weeks. Tlie infection may be sHght or
severe, but the trypanosome is not pathogenic, and the presence of
large numbers in the blood does not inconvenience their host. Intra-
peritoneal injections of cultures of the third and fourth generation,
fifteen and twenty-five days old, were found to be as efficacious as
injections of infective blood.]
[White rats (two), ordinary grey rats {M. rattus) (six), guinea-pigs
(four), and an owl (species ?), were found to be insusceptible.]
[The blood of cured animals does not agglutinate T. duttoni in
the blood of mice. The spontaneous formation of rosettes in
cultures prevents one seeing whether the blood of cured animals
causes agglutination. Such blood does not agglutinate T. lewisi in
rat's blood.]
[It is impossible to say with certainty whether T. duttoni is the
same as the parasite seen by Button and Todd, as these investigators
studied their flagellate only in the living state, and consequently
gave incomplete details of its structure. T. duttoni is peculiar to mice,
but appears to be inoculable into all species of mice. In spite of its
morphological and cultural resemblances, it cannot be confounded
with T. lewisi, because neither trypanosome is inoculable into the
other's host.]
[Kendall^ has described, under the name T. vmsciili, a trypano-
some which he found in about 8 per cent, of mice (M. nmsculus) in
Panama. He says that morphologically, in its great motility, and in
its mode of division it resembled T. lewisi. It was lo /i to i6 // long
by 3 M wide; the posterior end was pointed, and the nucleus, which
was round in young forms and more elongated later, was situated in
the centre of the body. This trypanosome was not pathogenic for
the mouse, and was not inoculable into rats.]
\T. musculi is much smaller than T. duttoni, which is 25 /* to 30 /x
long, so possibly it may be a distinct species.]
[Pricolo- found trypanosomes in at least forty out of a hundred
grey mice {M . musculus) caught in the garden of a laboratory in
Rome. In its general morphology (total length about 35 f.-, of which
free flagellum is about 12 /a), its great motility, and its inoculability
into white mice, this trypanosome resembles T. duttoni. The
number of parasites in the blood was found to vary from time to
time. A mild infection did not seem to incommode the mice, but
Pricolo found that mice harbouring many trypanosomes in the blood
when caught, usually died in twenty-four or forty-eight hours. Post-
mortem, there was anaemia of all the organs and serous effusion into
the pericardium.]
[Trypanosomes were found in fleas caught on the infected mice,
but no developmental stages could be made out in them.]
' [A. I. Kendall, /fwrw. Infec. Dis., v. 3, 1906, pp. 228-231.]
2 [A. Pricolo, Centralb.f. Bakter., I, Orig., v. 4.'; Part 3, 1906, pp. 231-235.1
102 TRYPANOSOMES AND THE TRYPANOSOMIASES
[Pricolo describes some interesting oDservations in connection with
this trypanosome. When fresh blood swarming with trypanosomes was
allowed to stand for ten hours, nearly all the parasites had disappeared,
and were replaced by rounded or oval bodies, free or intracorpuscular.
These bodies were also seen in stained specimens ; they were mostly
endoglobular, and all stages in the formation of these bodies were seen.
Pricolo regards them as resistant forms of the trypanosome, but it is more
likely that they were involution or degenerative forms than resistant
forms.
[Pricolo found that this trypanosome was able to pass through the
placenta and to multiply in the foetus, the latter showing a number of
different forms, which he considers as part of the cycle of development of
the trypanosome. Among the various multiplication forms were some
undergoing binary longitudinal fission ; others in the form of rosettes, with
the centrosomes towards the centre and the flagella peripheral ; others,
again, which seemed to divide transversely ; and, finally, many forms of
multiple division. In some the protoplasm had nearly or entirely disap-
peared, leaving only a rod-like centrosome and a nucleus, which gave rise
to forms closely resembling the Leishman body. Pricolo looks upon these
as phases in the progressive development of the bodies seen by him in the
blood. In addition, he describes bodies of the nature of oocysts, in the
interior of which young parasites, with nucleus and centrosome, are
developed. Holmes^ had previously drawn attention to similar forms
seen by him in the spleen and other organs in cases of surra. Moore,^
in a cattle trypanosomiasis observed in Nigeria, also describes coccus-like
bodies occurring free in the plasma. After pairing, they are said to invade
the red corpuscles, in which they become snail-shaped. These are again
extruded into the plasma, and this is followed by the appearance of many
trypanosomes in the blood, and by the extrusion of the ' tail-spot ' of the
parasites — apparently the same as the free coccus-like bodies.]
Section 2. — Trypanosome of the Bandicoot,
[T. bandicotti, Lingard.^]
According to Lingard, young and half-grown bandicoots [Mus
(Nesokia) giganteus] in Bombay and the Dekkan are infected with
trypanosomes. The adult animals are not infected. The proportion
of infected animals is 25 per cent. Lingard has not shown whether
this trypanosome of the bandicoot is the same species as that of
M. rattus and M. decuinanus. It is, however, very likely that they
are the same, for Lingard infected another species of Nesokia
{N . providens) with T. leicisi. Musk rats {Sorex ccerulciis) and mice
{M. spicatus) in the same districts are never infected.*
[We have seen (p. 69) that Lingard succeeded in infecting
guinea-pigs with the bandicoot trypanosome, but that the mule, ass,
and rabbit proved refractory. The fact that guinea-pigs died of the
infection tells against the identity of T. bandicotti and T. ]ewisi.~\
1 [Holmes, 'Evolution of T. evanst,' Journ. Comp. Path, and Thenip., v. 17,
1904^ pp. 210-214.]
- [Moore, Lancet, 1904, v. 2, p. 950.]
■' [Lingard, Indian Med. Gazette, December, 1904, p. 445.]
'' [The above paragraph appeared as a footnote on p. 56 of the original.]
DIFFERENT TRYPANOSOMES OF SMALL MAMMALS 103
Section 3.— Trypanosome of the Rabbit.
[T. cuniculi, Blanchard.]
This trypanosome was discovered by Jolyet and de Nabias in
1891.1 It was not rare in Bordeaux, at least at that time, for these
observers found it in four out often rabbits examined.
Jolyet and de Nabias give a good description of the movements
of the parasite, both of translation — flagellum end foremost — and
in loco.
They also describe agglomeration of two or three parasites
joined by their posterior ends, but still showing considerable motility.
In January, at a temperature approaching zero, the parasites remained
alive at least five days in an ordinary slide preparation, the edges of
the cover-glass having been ringed with vaseline. They appeared
to live very well in rabbit's blood kept at 41° and 42° C.
Fig. 16. — Trypanosomes of M. Rattus, of the Rabbit' (Petrie), and of the
Indian Squirrel (Donovan).
I. Two T. lewisi of M. rattus. 2. Three trypanosomes of the rabbit (from a preparation
of G. F. Petrie). 3. Two trypanosomes of Sciiiyus palmarum (from a preparation of
C. Donovan). All these trypanosomes were drawn with the camera India under the
same magnification, 1,400 diameters.
Blood fixed with osmic acid, then dried and stained with
concentrated alcoholic solution of dahlia-violet or fuchsine, enabled
Jolyet and de Nabias to study the structure of the parasite, which
is 30 ;a to 36 /i long (free flagellum 15 yii) by 2 /a to 3 /.i wide. These
observers saw the undulating membrane, the nucleus, and probably
also the centrosome, but they did not recognize the intimate relation
of the latter body with the undulating membrane.
' The health of the animals does not seem to be affected by the
presence of this animalcule, even though it be present in the blood
in very large numbers, at least hundreds of thousands, each drop of
blood containing more than fifty. It should be added, however,
that the parasite is to be met with more often in rabbits which are
wasted and ill, or in those which have suffered from diarrhoea, than
in healthy rabbits.'
1 F. Jolyet and B. de Nabias, Soc. (FAnat. et Physiol, de Bordeaux, Feb-
ruary 16, 1891 ; Joum. de Med. de Bordeaux, March 18, 1901 ; and Travaux du
labor, de M. Jolyet, v. i, 1891, pp. 39-42.
104 TRYPANOSOMES AND THE TRYPANOSOMIASES
Dr. M. Nicolle some years ago, in Constantinople, described a
trypanosome in the blood of cachectic rabbits. This trypanosome
was kept alive for a considerable time in the laboratory by passage
through rabbits. The inoculated animals showed the parasite in
their blood, became cachectic, and died. The trypanosomes were
never abundant in the blood, and only appeared in it at intervals.
The trypanosome of Nicolle was therefore pathogenic, but, unfortu-
nately, it has been lost. (Unpublished communication of M. Nicolle.)
In 1904 Petrie,^ at Elstree, Hertfordshire, found three perfectly
healthy tame rabbits spontaneously infected with a trypanosome
(Fig. 16, 2) which closely resembled T. lewisi of the rat — (i) in its
morphology (it is, however, a little smaller, and its post-centrosomic
end is very short and slender) ; (2) by its agglutination with the
serum of the horse, i in 10 ; and (3) by remaining alive for at least a
month in the refrigerator.
The parasite was abundant in the blood of Petrie's rabbits, one
of which had the trypanosome in its blood for six months.
The animals (ten rabbits, three guinea-pigs, one rat) inoculated
intravenously, intraperitoneally, and subcutaneously with this
trypanosome, did not become infected ; but, nevertheless, this
trypanosome-containing blood appears to be toxic, for four out of
the ten rabbits died, without any sign of bacterial infection.
[Although it was in tame rabbits that Petrie- first found the trypano-
some, further observations have shown that the infection is rare in tame
rabbits (230 examined, not a single one infected), but commoner in wild
rabbits (four infected out of forty examined). Petrie was unable to
transmit the infection to tame rabbits or to white rats. He succeeded in
cultivating the wild-rabbit trypanosome on rabbit-blood agar, forms
similar to those of T. hwisi being obtained.]
[Bosc^ found a rabbit spontaneously infected at Montpellier. The
trypanosome resembled that described by Petrie, but was slightly larger.
Bosc thinks that the centrosome and chromatic protoplasmic granules are
nuclear in origin. He also figures early stages of division and conjugation
forms, but many of his figures are unconvincing (Mesnil).'']
[The infection could not be transmitted to guinea-pigs, rats, or to three
rabbits out of four. The fourth rabbit had a very mild infection of short
duration.]
[Bettencourt and Fran^a^ found rabbits spontaneously infected in
Portugal, and Manca'' a young wild rabbit (Lepus ctiniculus) in Sardinia.
The animals did not appear ill. Bettencourt and Fran9a succeeded in
infecting two rabbits out of five inoculated intraperitoneally, the infection
lasting twenty days. Mice, rats, and guinea-pigs were refractory, which
proves the individuality of T. cuniciili.']
1 G. F. Petrie, Centralb. f. Bakter., I, Orig., v. 35, January 16, 1904,
pp. 484-486.
^ \Vt.tx\%Journ. Hyg., v. 5, 1905, p. 193.]
-' Bosc, Arch.f. Protistenk., v. 5, 1904, pp. 40-77.]
■• Mesnil, BiiU. Inst. Past.., v. 3, 1905, p. 144.]
* [Bettencourt and Franga, Arch. Inst. roy. de Bacter. Cainara Pesiana, v. i,
1906, p. 167.]
^ [Manca, C. R. Soc. Biol., v. 6q, 1906, p. 494.]
DIFFERENT TRYPANOSOMES OF SMALL MAMMALS 105
Section 4.— Trypanosome of the Guinea-pig-.
Kunstler recorded the existence of this trypanosome in 1883/
without giving a description of it. In 1898 he gave a figure of it,^
but without any description or context, nor was the magnification
mentioned. The figure represents a very long organism with a
much-folded undulating membrane extending from one end of the
body to the other. Posteriorly (?) it terminates in a flagellum which
is about one-third as long as the body. Anteriorly there is also a
flagellum quite as long as the first, but which does not appear to be
continuous with the undulating membrane. In the neighbourhood
of the anterior extremity there is a small oval granule, which is the
only detail of the internal structure of the parasite that Kunstler
figures. According to this figure the parasite is rather a Trypano-
plasma than a trypanosome properly so called.
Kunstler writes to us : ' It is so rare that I have only found it in a
few animals out of, perhaps, several hundreds which I have had the
opportunity of examining.'
We may just recall the fact that we obtained an abortive infec-
tion with T. lewisi in the guinea-pig.
Section 5. — Trypanosome of the Hamster.
[T. rabinowitschi, Brumpt;^ Trypanozoon criceti, Luhe.*]
This trypanosome, discovered by Koch^ and von Wittich'' in
1881 in the blood of the hamster (Cricetus friimentarins) , has since
been further investigated by Chalachnikov^ in 1888, and by Rabino-
witsch and Kempner^ in 1899.
The latter authors state, without giving any details, that the
trypanosome of the hamster is morphologically hardly distinguish-
able from that of the rat, but they find that the trypanosome of the
hamster cannot multiply in the body of the rat and vice versa. They
conclude that the trypanosomes of the hamster and rat constitute at
least two varieties of the same species, if not two distinct species.
They found that several rats which had been inoculated intra-
peritoneally with the trypanosome of the hamster, but unsuccessfully,
were able to resist a subsequent inoculation with T. lewisi. Other
rats, on the other hand, did • not acquire any resistance to the
^ Kunstler, C. R. Acad. Sciences, v. 97, 1883, p, 755.
2 Kunstler, Bull. Scienlif. France et Belgique, v. 31, p. 206.
' [Brumpt, C. R. Soc. Biol., v. 60, 1906, p. 162.]
* [Liihe, in the article on Blood Parasites in Mense's ' Handbuch der Tropen-
krankheiten,' igo6, v. 3, pp. 69-193.]
^ Koch. Mittheil. a. d. kaiserl. Gesiind., v. i, 1881, p. 8.
" Von Wittich, Centralb. f. t/iediz. Wissensch., 1881, No. 4. These two
references are taken from Rabinowitsch and Kempner's paper.
' Chalachnikov, ' Researches upon the Parasites of the Blood of Cold- and
Warm-blooded Animals,' Charkov, 1888 (in Russian).
^ Rabinowitsch and Kempner, loc. cit., pp. 275 and 277.
io6 TRYPANOSOMES AND THE TRYPANOSOMIASES
T. lewisi as a result of a previous inoculation with the trypanosome
of the hamster.
Most of the inoculation experiments with this trypanosome have
been done on rats. Von Wittich inoculated several guinea-pigs un-
successfully, but as the inoculations were made subcutaneously and
not intraperitoneally, no definite conclusions can be drawn from
these experiments.
Section 6.— Trypanosome of the Spermophile.
In the same work in which he speaks of the trypanosome of the
hamster, Chalachnikov mentions (p. 88) having found in the blood of
Spermophilus miisiviis and guttatus, of the district of Cherson (South
Russia), a trypanosome which he regards as being morphologically
identical with the trypanosomes of the rat and hamster. It
measures about i fj. wide by 30 yu, to 40 /a or more long. It lives in
broth and 0"5 per cent, salt solution for six days. Twelve per cent,
of the spermophiles were infected.
Section 7.— Trypanosome of the Indian Squirrel.
(Scturiis paUnarum.)
\T. indicum, Llihe, 1906.]
We have been able to make a careful study of the adult form of
this trypanosome, thanks to the preparations which Dr. Donovan, of
Madras, has been good enough to send us.
Of eleven squirrels examined in August, 1903, two only were
infected ; in one the parasites were fairly numerous, in the other
they were scanty. The trypanosome of the squirrel is closely allied
to T. lewisi. In the preparations which were sent us only those
forms, which in the case of T. lewisi we call ' thin adult forms,' were
present ; we did not see a single parasite undergoing division.
The general shape of the body (Fig. 16, 3) is the same as that of
T. lewisi. The posterior end is a little shorter, but the centrosome
is equally large and striking. The edge of the undulating membrane
is almost straight, and as in T. lewisi, and contrary to what is found
in the group brucci, it is only slightly folded. The nucleus is
situated nearer the middle of the body than in the lewisi, in which it
is anteriorly placed. The total length, including Hagellum, is 18 /x to
20 /li, which is a little less than that of lewisi. Fig. 16, 3 gives a
sufficiently clear idea of the trypanosome of the Indian squirrel.
To sum up, a differential diagnosis between this trypanosome
and T. lewisi is possible, although the differences are slight. We
cannot be sure that we are dealing with two morphologically distinct
species, for these differences are hardly greater than those which
may occur in the same species in different mammals (for example,
T. brucci in the horse and mouse).
But it is very probable that the two species are at least physio-
logically distinct, like the trypanosomes of the rat and hamster.
DIFFERENT TRYPANOSOMES OF SMALL MAMMALS 107
Section 8. — Trypanosome of the Common Dormouse.
( Myoxus arellanarius.)
[T. myoxi, Blanchard ; T. blanchardi, Brumpt.]
Galli-Valerio\has recently seen in the unstained blood of }\Iyoxits
avellanarius, probably of Swiss origin, two specimens of a flagellate.
He writes thus upon the subject : ' They present an elongated body
with one of the ends rounded, the other end prolonged into a
flagellum joined to the body by a thin membrane slightly folded and
motile by reason of its undulatory movements. The spherical
nucleus is situated towards the rounded end of the body. Some-
times these tv/o parasites became shrunken and assumed a spherical
form, but one could distinguish at the periphery a portion of the
•membrane and of the flagellum. They were about 22 /i long.'
Galli-Valerio concludes that the characters presented by these
flagellates show that they are closely allied to the trypanosomes.
[Brumpt- has found trypanosomes in the common dormouse,
Myoxus glis. Young animals were most frequently infected ; animals
a year old rarely harboured the parasite and appeared to be actively
immunized. Morphologically this trypanosome, to which Brumpt
has given the name T. blanchardi, closely resembles T. Incisi, and,
like it, has the nucleus nearer the anterior end.]
[After intraperitoneal injection, the trypanosomes multiply rapidly,
and from the third to the eighth day multiplication forms, similar to
those of T. lewisi, are seen in the blood. After the eighth day, all
the parasites are adult forms, no longer able to divide.]
[Infected animals do not appear ill. T. blancliavdi is not inocu-
lable into rats, nor T. lewisi into the dormouse.]
Section 9.— Trypanosomes of Bats.
[r. vesper tilionis, Battaglia.]
Dionisi,^ in 1899, recorded the occurrence of trypanosomes in an
Italian bat, Miniopterus schrcihersii. He found them frequently in
bats infected with intracorpuscular hsematozoa, as well as ifi healthy
bats. F. Testi* has also recorded them in bats in the Agro Gros-
setano. Sambon has recently told us that he found them in two
bats iji the Roman Campagna.
Trypanosomes undoubtedly exist also in the small bats of the
genus Phyllostuina, occurring in Brazil (Para). Durham^ having
placed a Stegomyia fasciata with one of these Cheiroptera, found the
bat dead on the following day and the mosquito gorged with blood.
1 Galli-Valerio, Centralb.f. Bakter., I, Orig., v. 35, p. 85.
2 [Brumpt, Revue Scientif., 1905, second semestre, pp. 321-332.]
^ Dionisi, Atti d. Soc.p.g. Siudi. di Malaria, v. i, 1899, p. 145.
* F. Testi, Boll. Soc. Zool. I/al., 1902, quoted from the Cenlralbl. f. Bakter.,
Referate, v. 34, p. 66.
° Durham, 'Report of the Yellow Fever Expedition to Para,' 1900, p. 79.
io8 TRYPANOSOMES AND THE TRYPANOSOMIASES
In this blood were numerous trypanosomes, which, according to
Durham, were different from those of the rat and of nagana.^
Dr. Donovan informs us that he has observed trypanosomes in
the blood of a large frugivorous bat, Pteropus mediiis, from the neigh-
bourhood of Madras. The infected animals were not very common,
and hitherto Donovan has not been able to find them again or to
send us preparations of their blood.
[Since then trypanosomes have been found in various other
species of bats in different parts of the world. In Vespertilio kuhli
(lo out of 26 infected) and in Myotis muriniis (7 out of 35) by
Ed. and Et. Sergent- in North Africa; in Vespertilio noctula
(2 out of 6) by Battaglia^ in Italy; in Pipistrcllus pipistrellus (3 out
of 8) by Petrie* at Elstree ; in V esperugo pipistrellus (5 out of 40) by
Kisskalt''^ at Giessen in Germany, and in 2 out of g by Bettencourt
and Franca'' in Portugal; in Vesperugo serotinus (i out of 4) and
Vespertilio nattereri (3 out of 14), also by Bettencourt and Fran9a.
Nicolle and Comte'' found nearly a quarter of the adult Vespertilio
kuhli in Tunis infected ; the young bats were never found infected.]
[The Sergents describe two forms of trypanosomes in bats. A smaller
one, rather like T. lewisi, with very pointed posterior end. Total length
20 /x to 24 /i, width 1-5 /Li, free flagellum 4 /x to 5 /u. Like T. lewisi, it is very
motile, the nucleus is rather nearer the anterior end, and the centrosome
is some distance from the posterior extremity. They call this trypano-
some T. nicolleormn, but it may be the same as T. vespertilionis (Battaglia,
1904), in spite of certain differences in the description given. In two of
the bats {V. kuhli) examined, much larger trypanosomes (25 ju to 30 /x long
by 6 /x wide) were seen, in fresh films only. The name T. vespertilionis
was given to these large forms, but as this had been previously used by
Battaglia for the small trypanosome described by him, a new name will
have to be found, if it be proved eventually that these large forms are a
different species. The Sergents themselves recognised the possibility of
these being individuals about to divide, though they say no intermediate
forms were seen. Woodcock^ suggests that they may be sexual (female)
individuals.]
[The trypanosome seen by Battaglia, which he calls T. vespertilionis
(1904), was 12 ;u to 15 /x long by 2 /x to 3 /x wide ; the undulating membrane
feebly developed, no free flagellum, and a large centrosome quite at the
posterior end of the body.-^ He thinks that T. vespertilionis, as well as
T. lewisi, multiplies by means of ' spores ' which originate from the
nucleus by division.]
1 [In the light of recent observations (see p. 37), it is quite possible that the
flagellates seen by Durham were parasites peculiar to the mosquito, especially as
the described trypanosomes of bats are so like T. lewisi, and Durham states that
those seen by him were different from those of the rat. See note by Mesnil, Bull.
Inst. Past., V. 4, 1906, p. 606.]
2 [Sergent, C. R. Soc. Biol., v. 58, 1905, pp. 53-55.]
^ [Battaglia, Aiiit. di med. navale, v. 2, 1904, fasc. 5.]
■• \V&\.x\^, Journ. Hyg., v. 5, 1905, pp. 191-200.]
^ [Kisskalt, Cenlralb. f. Bakfer., I, Orig., v. 40, 1905, pp. 213-217.]
" [Bettencourt and Franga, C. R. Soc. Biol., v. 59, 1905, pp. 305-307 ; Arch.
Inst. roy. de Bact^r. Cam'ara Pestana, v. i, 1906, pp. 187-194.]
' [Nicolle and Comte, C. R. Soc. Biol., v. 60, 1906, pp. 736-738.]
' [Woodcock, Quart. Joiirn. Micr. Sci., v. 50, 1906, p. 292.]
' [Mesnil, Bull. List. Past., v. 3, 1905, p. 286.]
DIFFERENT TRYPANOSOMES OF SMALL MAMMALS 109
[The trypanosome seen by Petrie resembles T. nicolleofum (Sergent).
In the fresh condition it is very active and shows more contortions than
T. lewisi. In stained films it often assumes a characteristic circular or oval
form, and hence it is difficult to measure accurately. One was 16 /x long,
including free flagellum 8 /x (see Fig. 17, ^ to 6). On rabbit-blood agar
at room temperature there were signs of commencing multiplication in
eight days, but the tube then became contaminated.]
[Kisskalt says that the trypanosome seen by him was probably the
same as Petrie's. It was smaller and more slender than T. lewisi, and in
fresh films some of the parasites looked almost like spirochetes. When
stained, the centrosome was found quite at the posterior end, and seemed
half out of the body. One of the bats harboured, in addition to the
trypanosomes, small ring-shaped endoglobular parasites containing one or
more chromatin dots. This parasite was found in eighteen other bats.
Kisskalt was unable to trace any connection between this parasite and
the trypanosome.]
[Bettencourt and Franja originally thought that their trypanosome was
Fig. 17. — Trypanosomes of the Mole (T. talpce) and Bat (T. vespertilionis).
(After Thomson and Petrie.)
I and 2. Trypanosomes of the mole, with nucleus and centrosome compact and sharply
defined ; in 2 the posterior end is partially retracted (Thomson). 3-6. Trypano-
somes of the bat, showing frequent contortions of the body (Petrie).
a new species, and called it T. dionisii, but in their later paper {loc. cit.) they
come to the conclusion, with which Mesnil agrees, that all the described
species of bat trypanosomes should be included in a single species,
T. vespertilionis, Battaglia, 1904.]
[NicoUe and Comte in Tunis studied, in stained films, the two forms
of trypanosomes described by the Sergents. The larger form they found
to be 24 yii, by 4 yu. ; free flagellum very short, 3 /"■ at the most. On account
of the association or the alternation of the two forms in the same bat, these
observers think that they belong to the same species.]
[These trypanosomes appear to be non-pathogenic for bats, and are
not inoculable into rats, mice, guinea-pigs, or rabbits. Nicolle and
Comte succeeded in only one out of twenty experimental inoculations
into healthy bats.]
[The carrier of the parasite is unknown ; Kisskalt examined two
fleas and many mosquitoes with negative results.]
[We may mention here that Laveran^ inoculated a bat, Pteropus
meditis, subcutaneously with the Mauritian surra trypanosome. The
bat became severely infected after five days' incubation, and died
nine days after inoculation — that is, sooner than the average rats
and mice inoculated with the same virus.]
1 [Laveran, C. R. Soc. Biol., v. 58, 1905, p. 8.]
no TRYPANOSOMES AND THE TRYPANOSOMIASES
Nicolle and Comte^ injected two bats {Vespertilio kuhli) intra-
peritoneally with the trypanosome of dromedaries in Algeria (see
Chapter VI.). The bats became infected after an incubation of
two days, the trypanosomes were most numerous at the end of four
days, and disappeared after six days. The bats died in eighteen
and twenty-two days (undoubtedly through captivity) without again
showing trj'panosomes in their blood. A control rat, inoculated at
the same time as the bats, died of trypanosomiasis in thirteen days.]
Section 10. — Trypanosome of the Mole. {Talpa, europea.)
{Trypanosoma talpce, new species.]
[Petrie,^ at Elstree, found six out of twenty moles infected with
trypanosomes. They were always scanty in the blood, and in size
and form resembled T. lewisi. Satisfactory stained preparations
were not obtained. A white rat was inoculated intraperitoneally
with infective blood, but was refractory.]
[Thomson,^ in May and June, igo6, found trypanosomes in three
out of fourteen moles examined at Elstree. All three moles
harboured in addition intracorpuscular parasites, but this may have
been merely a coincidence. Thomson was more successful than
Petrie in obtaining stained specimens of the parasite. Only adult
forms were seen, and they were fairly uniform in size and shape.
The most striking feature of this trypanosome is the long, pointed,
proboscis-like posterior end, looking sometimes almost like a posterior
flagellum. The nucleus is relatively small (2 /tt long) and lies close
to the ventral border. There appears to be a narrow, slightly-
folded undulating membrane (see Fig. 17, i and 2). The average
dimensions are as follows : Total length 2.yb //., free flagellum 5'2 )jl,
post-centrosomic end g"3 /it, greatest width about 3"5 /i. Intra-
peritoneal inoculation into a white rat and attempts at cultivation
proved unsuccessful.]
[This parasite of the mole appears to be a new species, for which
I propose the name Trypanosoma talpce.]
[Section 11. — Trypanosome of the Badg-er. {Meles tascus.y]
[T. pestaiiai, Bettencourt and Franga, 1905.]
[This trypanosome was found by Bettencourt and Fran9a* in
two badgers {Meles taxus) out of four examined from the neighbour-
hood of Cintra, Portugal. It is 30 /x to 32 /x long by 5 /x to 6'5 fi wide,
and is therefore relatively stumpy. The posterior extremity is long
and thin, the centrosome being a considerable distance (10 /a) from
the tip. There is a well-developed and actively motile undulating
membrane. The infected animals seemed quite well.]
1 [Nicolle and Comte, C. J?. Soc. Biol., v. 58, 1905, pp. 245, 246.]]
2 [Petrie, loc. cit., p. 194.]
3 [J, D. Thomson, /(jz^r??. Hyg., v. 6, 1906, pp. 574-579.]
* [Bettencourt and Fran(;a, Arch. Inst. roy. Bad. Cam. Pest., v. i, 1906,
PP- 73-75 ; also C. R. .Soc. Biol., v. 59, 1905, pp. 305, 306.]
CHAPTER VI
NAGANA AND ALLIED AFRICAN DISEASES
Historical Review and Geographical Distribution of Nagana,
and of the allied african trypanosomiases
Historical. — ' Nagana, or the fly disease,' says Bruce,^ who dis-
covered its parasite, ' is a specific disease which occurs in the horse,
mule, donkey, ox, dog, cat, and many other animals, and varies in
duration from a few days or weeks to many months. It is invariably
fatal in the horse, donkey, and dog, but a small percentage of cattle
recover. It is characterized by fever, infiltration of coagulable
lymph into the subcutaneous tissue of the neck, abdomen, or
extremities, giving rise to swelling in these regions, by a more or
less rapid destruction of the red blood-corpuscles, extreme emaciation,
often blindness, and the constant occurrence in the blood of an
infusorial parasite ' — a trypanosome.
The excellent astiological and experimental study made by Bruce
in Zululand will remain the fundamental work upon the subject of
nagana.
An infected dog was sent by Bruce to England in November,
i8g6. This was the starting-point of the researches of Kanthack,
Durham, and Blandford,^ which were carried on first in London,
then in Cambridge, from November, 1896, to August, xSgS. A
resume of this joint work on the tsetse-fly disease was published at
the end of 1898. It contains numerous interesting experimental
facts. It is to be regretted that the complete work has not
appeared.
Plimmer and Bradford^ continued these researches in London,
and occupied themselves mainly with the morphology of the
^ David Bruce, ' Preliminary Report on the Tsetse-Fly Disease, or Nagana,
in Zululand,' Ubombo, Zululand, December, 1895. ' Further Report,' etc.,
Ubombo, May 29, 1896; London, 1897. Nagana is a Zulu word which, accord-
ing to Bruce, alludes to the state of depression and weakness of the sick animals.
^ Kanthack, Durham, and Blandford, Proc. Roy. Soc, v. 64, 1898, p. 100.
^ Plimmer and Bradford, Proc. Koy. Soc, v. 65, 1899, p. 274; Centra! b. f.
Bakter., I, v. 26, 1899, p. 440 ; and Quart. Joiirn. Micr. Set., v. 45, February,
1902.
112 TRYPANOSOMES AND THE TRYPANOSOMIASES
haematozoon, which they called Trypanosoma brncei^ (xSgg), and
with its distribution in the bodies of infected animals.
It was also the Zululand parasite, for which we were indebted to
Miss Florence Durham and to Dr. W. Mitchell, which we used in
the series of investigations which we have carried out upon
Trypanosoma brucei.^
Nocard used the same parasite for the experimental demonstration
of the non-identity of nagana and dourine,^ and for his inoculation
experiments with cattle and sheep, and it was this parasite again
which Novy and McNeal used for their cultivation experiments.^
At the present time the study of this trypanosome has advanced
more than that of any other pathogenic trypanosome, and it may
therefore serve as a type.
The nagana of Zululand, or an allied disease, occurs in many
other parts of Africa. Its existence, as we shall see later on, is
associated with that of the tsetse-fly (genus Glossina), or, more
accurately, with that of one or a few species of that genus. It is
mainly, therefore, in the terrible accounts which explorers in South
and Central Africa have given us of the ravages caused by this fly
that it has been necessary until quite recently to study the distribu-
tion of the group of diseases with which we are dealing. All
references to the tsetse-flies in these accounts have been analyzed
and collated in the excellent monograph by Austen called ' Monograph
of the Tsetse-Flies,' from which we shall have occasion to quote
frequently.
Since the discovery by Bruce of a trypanosome as the causal
agent of nagana, the microscope has helped materially in the
elucidation of these ' fly diseases,' and at the present time papers
upon the microscopic examination of the blood of sick ,animals
and experiments upon laboratory mammals are becoming quite
numerous.
We may mention the works of Koch^ upon the trypanosome of
German East Africa ; of Theiler^ upon that of the Northern Trans-
vaal ; of Brumpt' upon that of Ogaden ; of Schilling,* Ziemann,"
^ [Plinimer and Bradford spelt it brucii, but Laveran and Mesnil state that,
according to the rules of nomenclature, the spelling should be brucei, which is the
form used by most authors.]
2 Laveran and Mesnil, C. R. Soc. Biol., March 23, 1901 ; Ann. Inst. Past.,
1902, V. 16, pp. 1-55 and 785-817 ; and Bull. Acad. AIM., June 3, 1902, p. 646.
3 Nocard, C. R. Soc. Biol., May 4, 1901.
* Novy and McNeal, yoz Livingstone, ' Missionary Travels and Researches in South Africa,' first
edition, 1857; 'The Last Journals,' London, 1874.
* [Ochmann, £eri. Tierarztl. Wochenschr., 1901;, No. 19, pp. 337, 338. The
animals were brought down from the cool uplands of Usambara, German East
Africa, to the hot coast districts, when several became ill and died. Five of
the pigs looked very ill and were unable to stand ; the respiration was hurried and
there was high fever (io5'8 F.). In three of the five animals many trypanosomes
were present, and in one the spleen was much enlarged the day before death.
The trypanosome was very short and broad, and had a very short flagellum. If
this should prove to be a new species, Ochmann suggests the name T. suis^
^ Stordy, The Veterinarian, v. 72, January, 1899, pp. 11-20, and June, 1899,
pp. 385-388. , . _ .,kS,
<> [The later observations of Nabarro and Greig in Uganda show that animal
trypanosomiases are more prevalent , there than was at first supposed (see;
Section 8, second part of this chapter.)]
NAGANA AND ALLIED AFRICAN DISEASES 115
In the country of the Somahs and the Gallas fly diseases have
been recorded at different times (Donaldson Smith in 1894, Prince
Nicholas D. Ghika in 1898), especially along the banks of the River
Webi-Shrebeli. In the same country, in the district of Ogaden,
Brumpt, naturalist of the mission of the Bourg of Bozas, observed
an epizootic due to a trypanosome amongst the camels of the
mission. This trypanosome is said to be carried by the Glossina
longipennis. The Somalis call this camel disease, as well as the fly
which conveys it, Ai'no. [Theiler^ has also recorded the presence of
this epizootic in thirty-four out of thirty-six camels that were brought
from Somaliland to Pretoria.]
Our knowledge of these diseases further to the north is much less
exact, but is being gradually extended.
Agatarchides and James Bruce have recorded the presence of
flies, probably tsetse-flies, in Abyssinia. During the English expedi-
tion in Abyssinia (1867) a large number of the horses died. The
veterinary surgeon, Hallen, who afterwards went to India, was struck
by the likeness of this Abyssinian epizootic to surra. ^
According to Savour^, in a recent paper in the Journal d' Agriculture
tropicale, surra occurs in cattle in Abyssinia. The disease appears to
have been imported from Bombay by the Italians. It is therefore
possible that in Abyssinia and Ogaden the trypanosomiasis is surra,
and not nagana. That is not the opinion of Brumpt, who thinks,
that this disease is the same as that occurring in the Juba Valley and.
in East Africa to the south of Juba River. He bases his opinion,
upon the commercial relations of Ogaden with these regions.
[Memmo, Martoglio, and Adani^ have described a trypanosome
epizootic, particularly virulent for cattle, sheep, and goats, in
Erythrea, the Italian colony along the south-west shore of the
Red Sea. Guinea-pigs, rabbits, dogs, and monkeys appear to be
refractory to this trypanosomiasis, which in this and other respects
resembles the disease described by Cazalbou in the French Sudan
(Haut-Niger, see later) under the name Souma.~]
[Balfour* and Head^ have described trypanosomiases amongst
donkeys, mules, and cattle in the Anglo-Egyptian Sudan. These
are possibly the same diseases as those recorded by Nabarro and
Greig in the animals in Uganda.]
Finally, we may quote the opinion of Westwood, that the tsetse,,
extending beyond its ordinary limits, gave rise to the fourth plague
of the ■ Egyptians. ' A host of very dangerous flies came into the
houses of Pharaoh, of his servants, and all over Egypt ' (Exod.
^ [Theiler, Revue giln. med. veter., v. 7, igo6, p. 298.]
2 Brumpt thinks it was horse plague, and not a trypanosomiasis {Soc. Biol.f
April 23, 1904, p. 675.).
^ [Memmo, Martoglio, and Adani, Ann. dUgiene Sper., 1905, pp. 1-46.]
* [Balfour, Brit. Med. Journ., 1904, No. II, pp. 1455, 1456 ; Edin. Med. Jour?t.y
N.S., V. 18, 1905, p. 202 ; Jour7t. Path, and Bact., v. 11, 1906, p. 209.]
^ [Head, /(S/^rw. Comp. Path, and Therap., v. 17, 1904, p. 206.]
8—2 .
ii6 TRYPANOSOMES AND THE TRYPANOSOMIASES
viii. 24). The fifth plague, the murrain of animals, would thus have
been the result of the fourth.^
We shall now examine the distribution of the fly diseases in the
river basins of West Africa.
Exact accounts of the existence of nagana in the Congo Free
State are still scanty. Bruce refers to Schloss on this point.
Broden (loc. cit.) has published observations upon trypanosome
epizootics occurring amongst cattle, sheep, and donkeys on farms in
the Free State around Leopoldville.^
At the south-eastern extremity of the Free State, in the district of
Katanga — that is to say, quite in the interior of Africa — the presence
of the tsetse-fly has been recorded by different explorers.^ These
flies were said to be quite harmless to cattle, donkeys, etc. ; but
a little further north, in the neighbourhood of Lake Moero,
Drs. Ascenzo and Derclaye have recorded a great mortality amongst
cattle and donkeys. All these observations, however, lack scientific
precision.
In Cameroon,* Ziemann has noted the existence of trypano-
somiases along the whole shore of the German colony. Cattle,
sheep, goats, donkeys, horses, mules, and dogs are attacked. Accord-
ing to this author, the trypanosomes differ more or less from those
which he observed in Togo in previous years, and the trypanosomes
in the blood of a sheep were specifically distinct from the trypano-
somes of Togo.
[After a more extended study of the trypanosomiases in Cameroon,
Ziemann^ has come to the conclusion that, in addition to nagana,
1 Westwood, quoted by Laboulbtee, art. 'Tsetse' in the 'Diction, encyclop.
des Sciences m^dic'
2 Broden saw seven head of cattle of the herd succumb to nagana (a
trypanosome morphologically almost identical with that of Bruce). He used the
blood of a cow to infect a goat, which still lives ; the trypanosomes are numerous
in its blood, and the temperature is raised frequently to 4r5° C. (106° F.). On
the same farm Broden saw two sheep die with trypanosomes in their blood. These
trypanosomes were only io'5 /i to I5'5 11. long by 17 /^ to 2'5 /n wide ; the flagellum
had no free portion. Broden suggests the name T. congolense for this trypano-
some, which he thinks is a new species. These trypanosomes killed a macaque
monkey in twenty-five days and a guinea-pig in twenty-six days. In the monkey
the trypanosomes presented a pleomorphism with forms identical with those of the
sheep and others, 20'5 \j. long, with free flagellum. The trypanosome in the guinea-
pig appeared to differ hardly at all from T. brucei ; the validity of the species
congolense is, therefore, somewhat questionable. On the same farm a young
donkey contracted a trypanosome infection, the parasites resembling those found
in the sheep. [In a later paper (Bull. Acad. ray. Belgigve, 4th ser., v. 20,
1906, pp. 387-416), Broden retains the name T. congolense provisionally. Since
writing his earlier paper, he has found trypanosomes in Bovidas in Stanleypool
and the region of the equator, and in dromedaries in Leopoldville. All the
trypanosomes were similar to those previously found in the ^heep and donkey.
Mesnil {Bull. Inst. Past., v. 4, p. 1026) thinks that the trypanosome is T. dinior-
phon^
^ Captain Lemaire, Bull. Soc. beige Geogr. Connnerc, 1900. Letter from the
Secretary-General of the Department of Finances of the Congo Free State,
June 20, 1903, and Letter from the President of the Special Committee, Katanga,
December 19, 1902 (communicated to one of us). We have examined the flies.
They are Glossina morsitans and Gl. longipalpis.
* Ziemann, Deutsche mediz. Wochenschr., 1903, April 9, p. 268 ; .'^.pril 16, p. 289.
^ [Ziemann, Centralb. f. Bakter., I, Grig., v. 38, 1905, pp. 307 and 429.]
NAGANA AND ALLIED AFRICAN DISEASES 117
which is mainly confined to the hinterland, there is an infection very
prevalent along the coast and in the river valleys, due to a trypano-
some, which he calls T. vivax, on account of its extraordinary motility.
This trypanosome is morphologically much like T. evansi, the parasite
of surra, and Ziemann agrees with Laveran and Mesnil in thinking
that possibly T. vivax may be the same as T. evansi, but is a species
distinct from T. brucei.]
[The fly diseases in Cameroon have also been studied by Diesing,i
who attempted to immunize cattle against nagana, and was to some
extent successful.]
[In 1903 Ziemann [loc. cit., p. 314) found a trypanosomiasis pre-
valent in Lagos amongst the domestic animals, the horses often
dying of the disease.]
In 1899 Christy recorded a trypanosome epizootic amongst horses
in Upper Nigeria.^
Likewise Hewby has noted the existence of a disease which
appears to be nagana along the north bank of the river Benue, in
Northern Nigeria.^ It was caused by the Gl. palpalis, and attacked
horses (which died in from three to ten weeks) and cattle. The
disease is caught solely during the rainy season.
[W. F. Gowers^ caught many specimens of tsetse-flies (Gl. morsitans)
near Yola, on the bank of the River Loko, a small tributary of the Benue.
The local natives all agree that cattle, horses, and donkeys are killed by
the bite of the fly, while it is harmless to sheep and dogs. Gowers adds :
' I fancy that the tsetse-fly will be found to be pretty well distributed
throughout the southern portion of Northern Nigeria.' The same observer
found Gl. fachinoides along the Benue River, between Lau and Lokoja, in
Northern Nigeria, and states that, with the exception of one or two small
spots, no horses or cattle can be kept in this area. Above Lau, however,
the river banks swarm with cattle, especially in the dry season (October
to April), when the fly is scarce.]
[In Southern Nigeria, Moore' has observed a fly disease in cattle
which presents certain peculiar symptoms not usually noted in
nagana.]
1 [Diesing, Arch.f. Schiffs u. Trap. Hyg., v. 9, 1905, pp. 427-431.]
^ Appendix H in Austen's monograph, p. 310.
■' In Dutton and Todd, 'Trypanosomiasis Expedition to Senegambia,' p. 44.
* [See in Austen, 'Supplementary Notes on the Tsetse- Flies,' Brit. Med.
Journ., September 17, 1904..]
^ [Moore, Lancet, 1904, v. 2, p. 15. The following symptoms were noted:
Diminution of milk, unwillingness to eat (due probably to a loosening of the
teeth), running from the eyes, and puffy swelling of the legs. The animals had,
difficulty in passing urine, 'hunching' themselves, and straining very much during
the act. The flow of urine was intermittent, suggesting loss of contractility of the
bladder. They wasted rapidly ; the lymphatic glands rapidly enlarged ; there was
moderate intermittent fever, and during the early stage the respiration was in-
creased and there was a dry, hacking cough.]
[After a month drowsiness supervened, deepening into profound slumber, which
lasted thirty-six hours, and ended in death. Most animals, however, died before
the sleepy stage from obstinate constipation and retention of urine (due probably
to paralysis of intestine and bladder). Trypanosomes were found in the blood by
Chichester, and one animal showed numerous and active spirochastes. (For the
appearances described by Moore in the blood, see p. 102). Fowler's solution
by the mouth did no good, but hypodermic injections of (alkaline) sodium arseniate
gave good results.]
ii8 TRYPANOSOMES AND THE TRYPANOSOMIASES
In Togo the existence of epizootics due to trypanosomes was first
established by Koch^ in 1895 by the examination of blood-films
which had been sent to him. This epizootic was studied with the
greatest care by Schilling {loc. cit.), v/ho has written about it in three
papers, to which we shall have occasion to refer later. There are in
Togo three species of tsetse-fly, of which Gl. morsitans is one, but
neither the flies nor the disease exist at the coast, both being con-
fined to the hinterland. The epizootic of Togo has also been studied
by Ziemann {loc. cit.) [and by Martini,^ and Laveran and MesniF].
[Ziemann states, in his paper already referred to, that ' Schilling
has in Togo ... in addition to the ordinary T. bnicei, rediscovered
the parasite T. vivax,' which Ziemann had found in the Cameroons
in 1903, and had already differentiated from T. bnicei. Schilling
thinks that T. vivax is not distinct from T. brucei, and that all the
trypanosomiases in Togo are nagana. Laveran and Mesnil have
recently concluded from their experiments on serum diagnosis that
Schilling's Togo virus is probably not nagana, and that Martini's
Togo virus is probably neither nagana nor surra.]
The French veterinary surgeon Cazalbou has recently noted that
the region of the Bani (a big tributary of the right bank of the Niger)
is badly infected. According to native reports, it is impossible to
keep alive any domestic animal along the banks of this river. Four
horse's taken along the banks of the Bani to 45 kilometres to the
south-east of Segou and kept there — two for one day and two for
four days — all became infected with trypanosomes. The insects,
which were caught in large numbers upon the horses, included
ordinary flies, tsetse, and horse-flies. Cazalbou thinks that the
trypanosomiases which developed in these horses were not of the
same species (different diseases from both the clinical and experi-
mental points of view) ; he admits that one of these species is very
probably nagana.
[Laveran* has examined a number of animals (sheep and dogs) which
were inoculated at Segou by Cazalbou with the blood of equines or
bovines suffering from trypanosomiases, and recognises the existence of
three distinct infections. A dog inoculated from a dromedary showed a
trypanosome identical with that of mbori and of surra, T. evansi ; a sheep
showed a trypanosome closely resembling T. dimorphon ; another sheep
showed a trypanosome which appeared to be that of souma. Laveran
thinks this is a new species, which he calls T. cazalboni. The Massina
appears to be the principal focus of souma, but this disease has also been
observed at Bamako and at Kati. According to Cazalbou and Pecaud,
the disease is propagated by horse-flies (Tabinidae). The trypanosome which
resembles T. dimorphon also appears to be a new species, for which Laveran
has recently proposed the name T. pecaudi.^]
[In 1904 Major F. Smith'' discovered a small trypanosome (about
1 Koch, Reiseberichte, etc., Berlin, 1898, p. 66.
2 [Martini, Zeitschr.f. Hyg. u. Infektionskrank.., v. 50, 1905, pp. 1-96.]
^ Laveran and Mesnil, C. R. Acad. Sciences, v. 142, 1906, see pp. i486, 1487.]
^ [Laveran, C. R. Acad. Suences, v. 143, 1906, pp. 94-98.]
5 Ibid., V. 144, 1907, pp. 243-247.]
* [See R.A.M.C. Jozirn., v. 3, 1904, p. 330.]
NAGANA AND ALLIED AFRICAN DISEASES 1x9
13 fi long) in a blood-film taken from an ox post-mortem in Sierra
Leone. Possibly this may have been the small form of T. diniorphon.
Smith states that Gl. palpalis is found all over the colony.]
In 1904 one of us^ observed trypanosomes which have the greatest
resemblance to the trypanosome of nagana (general appearance,
structure, size) in blood-films taken by Dr. Tautain, Secretary-
General of French Guinea, at the autopsy of a horse which died at
Konakry. This horse, which Tautain only saw the day before death,
staggered and was almost completely blind.
[Martin,"^ in 1905, found numerous trypanosomiases existing in
Lower Guinea, the mountainous districts of Fouta Djalon and of
Labe, and along the banks of the Niger. These diseases were acute
or chronic, and Martin found spontaneous infections in the horse,
ass, mule, ox, sheep, goat, dog, and pig. Nearly all the trypano-
somes had common characters, and appeared to belong to the type
dimorphon. The trypanosome of souma is also prevalent in various
parts of French Guinea.]
Information about the trypanosome epizootics in Gambia is
furnished by Button and Todd {loc. cit.), who collected it at the
same time that they were making their extended inquiries into the
distribution of human trypanosomiases, about which we shall have
more to say in another chapter. The disease amongst horses exists
at the coast, at Cape St. Marie, and along the whole extent of the
Gambia, It is very common, and is largely responsible for the great
mortality amongst horses in the colony. This trypanosome of the
horse is different from that of nagana, and will form the subject of a
special chapter (Chapter VII.). At Maka, in French Senegal, quite
close to the frontier of Gambia, 150 miles inland. Button and Todd
also observed two horses infected with trypanosomes, which must
have been caught in English territory. From the similarity of the
symptoms they thought that the so-called ' malaria ' of horses which
is seen at St. Louis, in Senegal, was the same trypanosome epizootic.
The existence of a similar epizootic, endemic in the region of Upper
Senegal, between Kayes and the Niger, had already been rendered
probable by the works of the French veterinary surgeons Bupuy,^
Lascaux, Richard, and Pierre.* Button and Todd also saw cases of
this disease, but were unable to discover a trypanosome in associa-
tion with it.
■ 1 A. Laveran, C. A'. Sac. Biol., February 27, 1904, pp. 326, 327.
2 [^Q_ Martin, Ann. Hyg. et Mid. Colon., v. 9, 1906, pp. 304-314; C. R. Soc.
Biol., V. 61, 1906, pp. 107-109.]
' Dupuy, Rec. Med. Vitir., 1888, pp. 535 and 594 ; 1889, p. 253.
■* Pierre, see report, Cadiot, Bull. Soc. cent. med. viUr., March 30, 1896.
p. 148. Concerning the parasite Pierre writes thus : ' Almost constantly we have
met with in our preparations a crescentic element, thickened and pigmented at
; the summit of the arc ; a transparent zone clearly marked off from the rest of the
little body sometimes joins the extremities of the crescent. The disappearance of
the parasites amongst the red corpuscles is sometimes very rapid, and if one does
not take care to fix the blood previously upon the slide they disappear before there
is time to make out their characters' (pp. 154, 155). Pierre thought the disease
identical with human malaria and Indian surra.
120 TRYPANOSOMES AND THE TRYPANOSOMIASES
Observations in Cameroon and in Gambia show that these
trypanosome epizootics may exist close to the coast. We tind them
also occurring in the heart of the African continent. Thus Dr. Morel/
medical officer of the colonial forces, has furnished accurate informa-
tion upon the distribution of trypanosome diseases in the region
of Lake Chad. The tsetse-flies (probably Gl. morsitans from the
specimens which we have been able to examine) and nagana only
exist along, and close to, the banks of the River Shari. The disease
occurred during the rainy reason, and attacked horses, donkeys, and
cattle. A favourite habitat of the fly is a large sensitive plant.
Mimosa polyacantha. Along the shores of Lake Chad there is no
mimosa, no fly, and no nagana.^
In blood-films taken by Morel from sick animals we found a
trypanosome closely resembling T. brucei in shape and size.
More recently another colonial surgeon, Decorse, has observed,
also in the Shari Valley (at Kousri and Fort Archambault), epizootics
amongst horses and cattle. In blood-films which he has given us
we have seen a trypanosome differing markedly in its dimensions
from T. brucei. Its average length is 15 //. (instead of 25 im to 30 /i),
and its width is in proportion. There seems to be no free flagellum,
but we cannot be quite certain about this. It resembles T. dimorphon
of Gambia (see Chapter VII.). In this region Decorse caught many
specimens of Gl. tachinoides^ and also some of Gl. morsitans. He
noted that the tsetse-fly exists there independently of the mimosa.
The trypanosomiases of camels and cattle in the regions of
Timbuctoo and of Massina have formed the subject of careful
investigations by Cazalbou, who has written several papers on them
in the Bull. Acad. Med.^ These trypanosomiases will be considered
in a special paragraph later (see also p. 118).
Do trypanosome epizootics, allied to nagana, occur in Algeria ?
It appears to us that this is no longer a debatable point, since the
discoveries by Szewczyk^ and Rennes^ of a trj^panosome epizootic
amongst the horses of the Spahees in the extreme south-west of
Algeria (valley of the Zusfana), and by the brothers Sergent^ of a
1 Morel, Ann. Hyg. and MM. colon,, v. 5, 1902, p. 305, and v. 6, 1903, p. 264.
2 [Brumpt (C. R. Sac- Biol., April 16, 1904, p. 629), however, makes the follow-
ing statement : ' Gl. decorsei {i.e., Gl. tachinoides) has been found only in the Shari
basin and along the shores of Lake Chad' (italics not in the original), ' where it
seems to exist exclusively at the water's edge.']
^ [In the original of Laveran and Mesnil's book this is called Gl. palpalis, var.
tachinoides (Austen), but from the study of further material Austen has come
to the conclusion that Gl. tachinoides (Westwood) is in reality a perfectly
distinct species. See Austen, ' Supplementary Notes on the Tsetse-Flies,' Brit.
Med. Journ., September 17, 1904/] It is undoubtedly the same species which
Brumpt {Soc. Biol., April 16, 1904, p. 628) has recently described under the name
Gl. decorsei, n. sp.
* See the reports of Laveran, Bull. Acad. Med., June 30, 1903, p. 307 j
April 26, 1904, p. 348.
^ Szewczyk, Bull. Soc. centr. me'd. v^tilr., April 30, 1903, p. 218.
" Rennes, ibid., September 30, 1903, p. 424, and April 30, 1904, p. 248.
'' Ed. and Et. Sergent, C. R. Soc. Biol., January 23, 1904, p. 120.
NAG AN A 121
-disease amongst dromedaries in the district of Constantine. In
discussing later on the characters of these epizootics and their
relation to nagana, we shall show that it is difficult to identify them
with dourine, the only trypanosome epizootic known in the North of
.Africa down to 1903. The case of the horse seen by Chauvrat in
1892 must also, in all probability, be classed with these diseases allied
to nagana.^
In the following pages we shall be concerned solely with the
nagana of Zululand and its trypanosome discovered by Bruce. We
shall then consider the trypanosomes of the African diseases allied
to nagana, about which we have rhore or less accurate information,
drawing particular attention to the points in which they resemble,
and differ from, nagana.
NAGANA.
Pathogenic Agent : Trypanosoma bnicei, Plimmer and Bradford,
1899.
Section 1 . — Animals susceptible to Nagana. Refractory Animals.
Man. Symptoms and Course of the Disease among-st the
Different Species of Animals.
Whereas the majority of protozoal diseases (malaria, piroplasmosis,
etc.) are confined to a particular animal species or to a small number
of allied species, nagana, like almost all the trypanosome diseases, can
occur in a large number of species of mammals.
The list of species susceptible to nagana, whether naturally or
experimentally, is already a long one, and even now is far from
complete. One may say that, with very few exceptions, all mammals
are susceptible to nagana. A certain number of species, especially
ruminants living in the wild state, appear to have great tolerance,
for they can harbour the T. brucei in their blood without being
inconvenienced thereby ; but they are not really refractory. We
shall have occasion to refer to these cases again later, especially in
the Section dealing with the spread of nagana.
Fortunately man is refractory to this terrible disease. Living-
stone, Foa, and all the explorers who have travelled in countries
where nagana is prevalent, relate that they have been bitten
thousands of times by tsetse-flies without experiencing anything
more than slight irritation analogous to that produced by mos-
quitoes.^
Other than mammals, we do not know of any animal susceptible
to nagana. Birds are particularly refractory, the destruction of the
trypanosomes inoculated apparently depending upon the high tempera-
^ Chauvrat, Rec. m^d. veUr., 1896, p. 344.
2 The recent discovery of a human trypanosomiasis does not invalidate this
assertion, since the trypanosome is different from T. brucei.
122 TRYPANOSOMES AND THE TRYPANOSOMIASES
ture of birds {vide infra). [Schilling^ has, however, succeeded in infect-
ing geese experimentally with his Togo virus, which he calls nagana,
but which Laveran and Mesnil think is probably not nagana, but an
allied disease. Mesnil and Martin,^ who repeated Schilling's experi-
ments, found a goose susceptible to the original Zululand T. brucei.
Goebel,'' using Laveran and Mesnil's virus, recently succeeded in
infecting fowls.]
Nagana can be easily inoculated, and inoculations always succeed
provided they are made beneath the epidermal or epithelial layers.
When blood containing trypanosomes is injected into a vein or into
the peritoneal cavity, infection takes place more quickly than when
the inoculation is made in the subcutaneous tissue, but by the latter
method infection occurs just as certainly as by the former.
The duration of the incubation period — that is, the time which
elapses between the inoculation and the appearance of the parasites
in the blood — varies with the species of animal, with the number of
trypanosomes injected, and with the stage in which the parasites are
on injection.
[Several observers have also found that the virulence of a particular
trypanosome for the same species of animals may become increased by a
series of passages, until finally a stage of vims-fixe is reached. This
increase in virulence is evidenced by a shortening of the incubation period,
but more especially by a diminution in the duration of the disease. Thus,
working with the same strain of parasite (the Zululand T. brucei), Laveran
and Mesnil found the virulence for guinea-pigs greater than Kanthack,
Durham, and Blandford had done, as regards both the incubation period
and the total duration of the infection. Jakimoff, again, found the same
parasite more virulent than Laveran and Mesnil had done. Nabarro and
Stevenson, with the same strain of T. brucei which they obtained from the
Lister Institute, London, in a rat, found that at first guinea-pigs lived for
eight to eighteen weeks after inoculation, but that after a considerable
number of passages through guinea-pigs, a stage of virus -fixe was
reached, which killed the animals in fourteen or fifteen days. Martini
found, in his experiments with the Togo virus, that a low virulence was
often associated with a short form of trypanosome without free flagellum.
After several passages through animals, trypanosomes with free flagellum
appeared, and this was accompanied by an increase of virulence. This
relation of virulence to length of flagellum was by no means constant,
however.]
When the fluid injected contains a very small number of parasites,
the incubation period is longer than when blood rich in trypanosomes
is injected. The incubation period is also prolonged when the
trypanosomes have been kept for one or two days at the room
temperature, or exposed for one or two hours to a tempera-
ture of 40° or 41° C. This will be referred to again later. The
diminution in virulence is manifested only by this prolongation
' [Schilling, Art. a. d. kaiserl. Gesund., v. 21, 1904, p. 476.]
'^ [Mesnil and Martin, C. R. Soc. Biol., v. 60, igo6, p. 739.]
' [O. Goebel, ibid., v. 61, 1906, p. 321.]
NAGANA 123
of the incubation period, the infection itself being just as severe.^ In
the experiments to be described, infection was always produced,
except when otherwise stated, by the injection of numerous trypano-
somes in a normal condition.
In certain animals, especially rats and mice, T. brucei multiplies
rapidly and regularly, so that the microscopical examination of the
blood is sufficient to study the progress of the infection. In other
animals the tr3'panosomes are very scanty, at least at certain periods
of the disease, so that the diagnosis cannot be made by a simple
blood examination. It is then necessary to inoculate i to 3 or
more c.c. of blood from the suspected animal into an animal in
which the evolution of nagana is rapid and progressive. Throughout
this volume we shall come across numerous instances showing that
it is often indispensable to have recourse to inoculation experiments
in order to be certain whether an animal is infected or not. (See
especially the observations upon the pig, sheep, goat, and ox.)
The duration of the disease produced by T. brucei varies greatly
with the animal species ; from this point of view animals may be
divided into three groups :
(i) Animals in which nagana runs an acute course : mouse, rat,
lield-mouse (Arvicola), marmot, hedgehog, dog, monkey, [cat,
fox, squirrel] ;
(2) Animals in which nagana runs a subacute course : rabbit,
guinea-pig, field-mouse [Mns sylvaticus), garden dormouse (Eliomys
quercinus), equines, pig ;
(3) Animals in which nagana runs a chronic course : cattle, goat,
sheep, [goose, fowl].
The three forms of nagana may be studied in the above order.'
[The table^ on p. 124 summarizes the results obtained by different
investigators in various animals infected with nagana.]
^ The following table shows clearly the influence of the number of trypanosomes
injected, and of the mode of entry, upon the length of the incubat'on period.
Fluid inoculated.
Incubation Period in the Mouse inoculated with
uV c.c. Fluid.
Intraperi toneally.
Subcutaneously.
Blood rich in tr> panosomes,
diluted I in 5
The same, diluted i in 500 ...
The same, diluted i in 50,000
1 day (died in 3 days).
2 days (died in 4 days).
4 days (died in 6 days).
2 days (died in 5 days).
4 days (died in b\ days).
5 days (died in 7 days).
^ For a number of details see Laveran and Mesnil, Bull. Acad. Mdd., June 3,
1902, p. 646.
^ [This table is not in the original French edition.]
1
1
m
S-2
(5-9 days) in rats
and mice, after
i nj ec tion of
t r y p a n somes
passed through
the pig or sheep.
3 This was a
spleenless cat.
'i After pas-
sage through a
sheep one ^ dog
showed an incu-
bation period of
7 days, and total
duration of 21J
days.
* Post-mortem
advanced p u I -
monary tubercu-
losis present.
/.P. means
' intraperitoneal
inoculation.'
Su&c. means
'subcutaneous
injection.'
The numbers
in brackets ,de-
note average
duration.
Note. — Schil-
ling's and Mar-
tini's experi-
ments with the
Togo virus are
given separately
later.
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NAG AN A 125
(1) Animals in which Nagana runs an Acute Course.
Rats and Mice. — The course of the disease is the same in tame
rats (white and speckled), in sewer rats {Mus decumanus), and in tame
or wild mice.
A rat from which the spleen had been removed eight days
previously behaved exactly like a control rat, as did also rats highly
immunized against T. lewisi.
When an animal receives subcutaneously a moderately large dose
of trypanosomes — for example, ^ c.c. of blood containing many
parasites — the incubation period is about two days ; with a smaller
dose the incubation period is longer, and may even reach ten to
twelve days. The duration of the incubation period gives important
information about the number of trypanosomes contained in a
specimen of blood when the microscopic examination is negative.
After intraperitoneal inoculation of a fairly large dose of the
parasites, the incubation period is less than twenty-four hours, and,
together with a multiplication within the blood-stream, there occurs
an intraperitoneal reproduction of the parasite.
Upon this question of incubation period we are quite in accord
with English observers. We do not agree with them, however,
concerning the total duration of the infection : Kanthack, Durham,
and Blandford give, for rats, from six to twenty-six days (average
twelve) ; for mice, from eight to twenty-five days (average thirteen) ;
Bradford and Plimmer give from six to nine days for rats and mice.^
Starting, as these observers also did, with an incubation period of
two days, we found the total duration of infection, incubation
included, to be only three and a half to five and a half days. After
intraperitoneal inoculation, there is an incubation period of some
hours, and the animal dies in two and a half days or in three days
(rat and mouse respectively).
From the time that the trypanosomes appear in the blood, their
numbers increase constantly and regularly until death, when they
are as numerous as, if not more so than, the red blood-corpuscles.
If the incubation period has been prolonged, the animal usually
succumbs, as in the previous cases, two or three days after the first
appearance of the parasites in the blood.
There are some exceptions to this rule. Animals inoculated with
the blood of a pig (in the third month of the disease) or of a sheep
(in the fourth and sixth months of the disease) sometimes suffer from a
long infection (five to nine days instead of two or three). The
trypanosomes, after having appeared in the blood, diminish in
number for a time and then increase again. The trypanosomes of
these animals suffering from a mild infection, inoculated into other
rats and mice, are of ordinary virulence. We had a similar result on
[One of Bradford and Plimmer's rats died in five days; loc. cit., p. 463.]
126 TRYPANOSOMES AND THE TRYPANOSOMIASES
inoculating into a rat trypanosomes which had been kept in contact
with toluidin blue until they were completely motionless.^
The temperature in the case of two of our rats showed no definite
rise. During life there is no lesion or morbid symptom^ noticeable,
but the animals appear in good health until the approach of death.
The majority of mice and a certain proportion of rats appear drowsy
in the last hour of their life and die without convulsions. Some
mice and the majority of rats, on the other hand, while apparently
perfectly healthy, become very excited ; this is followed by convulsions
immediately preceding death.^
[Jakimoff* found that rats and mice inoculated by him behaved
similarly. For details of the incubation period and duration of the
infection, see Table, p. 124].
Field- Mice {Arvicola arvalis). — We have experimented upon six
field-mice, two inoculated intraperitoneally and four subcutaneously.
Although it is difficult to keep these animals alive long when in
captivity, fairly definite results were obtained with them. Two of
them behaved exactly like rats or mice which served as controls :
the trypanosomes appeared rapidly in the blood and quickly increased
in numbers, the animals dying in four days with very many trypano-
somes in the blood. The spleen was three times the normal size.
The other field-mice contracted a less acute infection ; the trypano-
somes appeared in the blood quickly or onty after four to six days,
but in all cases they were scanty in it. The animal then died in
about a week, but death was undoubtedly hastened by captivity.
The spleen was enlarged.
Marmots. — According to Blanchard,^ who used the same virus
as we did, the marmot, when awake and also when very lethargic,
suffers from an acute infection with many trypanosomes in the blood,,
death occurring in nine to fourteen days. On the other hand, when
sound asleep the marmot is either less susceptible or entirely
refractory. Unfortunately, the experiment quoted by Blanchard
does not lead to any definite conclusion.
Hedgehogs. — Kanthack, Durham, and Blandford inoculated a.
hedgehog. Infection occurred rapidly, and the animal died
seventeen days after inoculation, having lost a quarter of its original
weight.
We have also experimented upon a hedgehog weighing
1 One of our rats survived after having shown trypanosomes in its blood. This-
rat was inoculated intraperitoneally on April 26, 1901, with a mixture of equal
volumes of toluidin blue and of trypanosome-containing blood injected after being:
mixed for fifteen minutes, when the trypanosomes were quite motionless. On
May I trypanosomes were present in the blood ; on May 3 they Avere very scanty,,
after which the examinations were always negative ; tested later this rat was not
immunized.
2 Kanthack, Durham, and Blandford note lesions of the eyeball in their rats.
3 Our researches include observations upon more than 500 rats and mice.
4 [W. L. Jakimofif, Centralb.f. Bakter., I, Orig., v. 37, p. 668.]
^ R. Blanchard, C. R. Soc. Biol., July 25, 1903, p. 1122.
NAG AN A
127
420 grammes, which was inoculated subcutaneously on January 7,
1903.
Trypanosomes appeared in its blood after four days. They were
scanty for several days, then very numerous from January 16 to 18, and
more so on the 19th and 20th, when the animal died. The disease lasted
thirteen days. At the time of death' the animal weighed only 340 grammes.
Spleen weighed 10 grammes, undoubtedly much enlarged.
Dogs. — The dog is very susceptible to nagana. The incubation
period, after subcutaneous injection, was from four to six days in the
experiments of Kanthack, Durham, and Blandford, from two to four
days in our own. Fever is often slightly marked; in the majority of
cases the temperature is raised from the third to the fifth day, but
1 2 J 4 5 6 7 8 9 10
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Fig. 18.-
A and B, Our own observations. C. After Bruce. In the case of dogs A and B the
weight is noted. In the case of dog C the dotted lines represent the variations in the
number of trypanosomes present, the figures indicating the number of parasites per
cubic millimetre of blood.
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-Temperature Charts of Three Dogs with Nagana.
never goes beyond 40° C. [104° F.]. Bruce noted continued fever
with exacerbations to 40° and 41° C, and we have had similar cases-
(see charts. Fig. 18).
The total duration of the infection was from eight to sixteen days
in Bruce's experiments ; from fourteen to twenty-six (average
eighteen) in those of Kanthack, Durham, and Blandford ; from six
to fourteen in the experiments of Nocard and in our own. In one
instance one of our dogs died twenty-one and a half days after
inoculation, the incubation period lasting seven days. It had been
inoculated with blood containing few trypanosomes, probably of
modified virulence by passage through a sheep.
During the last hours of its life the dog appears very weak, and it
128 TRYPANOSOMES AND THE TRYPANOSOMIASES
dies without apparently suffering. (Edema of the genital region
(sheath, testicles), with considerable hypertrophy and congestion of
the inguinal glands, is frequently, but not constantly, present. Less
frequently, transient oedema of the face, particularly of the eyelids,
and opacity of the cornea are observed. We have never seen, as
have Bruce, Kanthack, etc., blindness following these corneal
troubles ; nor have we ever seen the pustular eruption described by
Bruce. The animal rapidly wastes and often presents transient
paresis.
When the course of the disease is rapid (six to nine days), the
trypanosomes constantly increase in number from the time that they
appear in the blood, or, rather, their number remains stationary for
several days and increases later. When the disease lasts twelve days
there is generally a diminution in the number of parasites, followed
by an increase, which lasts until death. Finally, in our dog which
lived for twenty-one and a half days there were several such periods
of diminution, followed by an increase.
Speaking generally, one may say that, after the rat and mouse,
the dog shows most trypanosomes in its blood during the course of
the disease.
Cats. — The cat appears less susceptible than the dog to nagana,
and perhaps, when nagana in the cat has been more studied, it will
be necessary to classify this animal with those in which the disease
runs a subacute course.
Kanthack, Durham, and Blandford give five days as the incubation
period. Death occurs in twenty- two to twenty-six days. The animal
has fever ; trypanosomes are present in the blood, but their number
shows marked daily fluctuations. As with the dog, an affection of
the aqueous humour, with fibrinous deposits in the anterior chamber,
and opacity of the cornea, are observed.
Plimmer and Bradford state that trypanosomes are less numerous
in the cat than in the dog. A cat from which the spleen had been-
removed died twelve days after inoculation with nagana.
We have never experimented on cats, and can only quote the
following observation, for which we are indebted to Dr. Chantemesse.
On October 20, 1903, a cat ate an infected mouse which had just died.
A month later the cat was losing weight, its head was swollen, and its
eyes affected. These troubles became more marked, and the animal
died on December 3, forty-four days after this accidental inoculation. The
blood swarmed with trypanosomes, the spleen was considerably en-
larged, (35 grammes for an animal of 2,040 grammes) ; the Hver was also
enlarged. The animal was completely blind owing to opacity of the
cornea and lens. All round the eyes the hair had fallen away and scabs
had formed. 1
^ Since then we have observed another cat, which died twenty-five days after
having eaten an infected guinea-pig, with practically the same symptoms as the
preceding ; during the last days of its life trypanosomes were numerous in the
blood.
NAG AN A 129
[Ziemanni inoculated a cat with T. brucei from a chronic case in a
horse; the incubation period was five days, and the disease lasted
thirty days. Lacomme^ has recorded two cases of nagana in cats
which had eaten rats just dead of the disease; the cats died in
twenty-eight and fifty-two days. For other experiments on cats
see table, p. 124.]
Monkeys. — Monkeys, at least the genus Cercopithecus, are easily
infected, trypanosomes rapidly multiplying in the blood, where they
are met with in large numbers. The disease had an average duration
of fifteen days, and terminated fatally in each of three cases. A
baboon inoculated by us proved refractory.
The chief symptoms are : fever, anaemia, oedema (very slight in
the case observed by us), and general weakness, which becomes
very marked in the last stages of the disease. About the fourth day
after inoculation the temperature rises from the normal (37' 5° C. in
the monkey^) to about 40° C, and after remaining up for several
days, falls again to normal. The monkey, of which a detailed
account is given below, died with a remarkably low temperature ;
the day before death the rectal temperature was only 28*5° C.
[83-4° F.].
Kanthack, Durham, and Blandford experimented upon a Macacus
rhesus ; it survived the inoculation a fortnight, and died in ' an
advanced condition of pulmonary tuberculosis . . . ; very many
hsematozoa were present in the blood until death occurred.'
Nocard experimented upon ' an old Macacus, active and very
spiteful, which received under the skin of the tail several drops of the
blood of a mouse. Four days later the monkey was quiet, refused its
food, and allowed itself to be handled with impunity. Its temperature
rose to 41° C. [106° F.], and the blood contained an enormous
number of trypanosomes.' This monkey — so Nocard kindly informed
us — died fifteen days after inoculation ; it had fever, oedema of the
eyelids and pouches, and very many parasites in the blood from the
fifth day onwards. At the time of death the parasites were more
numerous than the red corpuscles.
A Cercopithecus we inoculated with nagana died in thirteen days.
As it showed certain symptoms resembling those produced by the
inoculation of T. gambiense, we reproduce the detailed record of
the monkey as we presented it to the Academie de Medecine in 1902.
A monkey, Cercocehus fuliginosus {Cercopithecus), was inoculated on
March 23, 1902, under the skin of the abdomen with the blood of a mouse
which had just died of nagana. At the time of injection the trypanosomes
were very motile.
Rectal temperature of the monkey before injection, 37-6° C. [99'6° F.].
Weight, 2,040 grammes.
' [Ziemann, Centralbl. f. Bakter., I, Orig., v. 38, p. 314.]
^ L. \^z.zoraxa^, Joiirn. de Phys. et Path, gen., v. 8, 1906, pp. 115-117.]
^ [In Uganda we found the average normal temperature of monkeys {Macacus
and Cercopithecus) to be \qi'i° F. (39° C.).]
130 TRYPANOSOMES AND THE TRYPANOSOMIASES
March 26 : Few trypanosomes in the blood.
March 27 : Trypanosomes very numerous. In the evening the tempera-
ture rose to 40° C. [104° F.] ; the monkey does not appear ill, and has a
good appetite.
March 28 : Trypanosomes numerous; E. 40*1° C. i04'2° F._.
March 29 : Trypanosomes numerous ; E. 39"9° C. io3'8° F.].
March 30 : Trypanosomes have appreciably diminished ; M. 367° C,
[98° F.]. The monkey is less lively than usual, but eats well.
March 31 : Trypanosomes very scanty ; M. 38-1° C. [ioo-6° F.].
April i: Trypanosomes scanty; M. 37-4° C. [99-4° F.] ; E. 39-8° C.
[103-6° F.].
April 2 : Trypanosomes scanty ; M. 36-4° C. [97-6° F.] ; E. 36-3° C.
[97-4° F.]. The monkey is getting weaker ; remains quiet almost con-
tinually, with his head between his legs. A little cedema of the right
eyelids present ; appetite diminished.
April 3 : Trypanosomes scanty ; weakness increasing, subnormal
temperature very marked ; M. 34-4° C. [94° F.] ; E. 33-4° C. [9_2-2°_F.].
April 4 : The monkey is so weak that it can hardly maintain the
sitting posture ; it constantly reels and falls on its side. The tempera-
ture continues to fall, reaching only 28-5° C. [83-4° F.] in the rectum.
Trypanosomes very scanty. The blood is very fluid, and flows freely
from a small cut in the ear, which was made to obtain blood for examina-
tion. The blood fixes badly, and the red corpuscles are greatly diminished
in number.
The monkey was found dead on the morning of April 5. It weighed
1,920 grammes; the spleen, 19-5 grammes. The tissues were anaemic;
the blood watery, as in the severe anaemias ; no oedema or infiltration of
the serous membranes ; urine normal.
[Fox. — Jakimoff injected a fox subcutaneously. The incubation
period was short — three days — and the trypanosomes were very
numerous, coming even to exceed the red corpuscles in number.
The disease ran a very acute course, death resulting on the eighth day].
[Squirrel. — Mathis^ has shown that the squirrel is susceptible to
experimental inoculation. A common French squirrel {Sciurus
vulgaris) became infected after an incubation period of seven days,
and died thirty-eight days after injection. In an Annamese squirrel
{Sc. griseimanus) the incubation period was four days, and the total
duration of the infection nineteen days. Trypanosomes were very
numerous in the blood, and the animals did not appear ill until a
few days before death. In one case there was opacity of the cornese
and marked wasting. Both animals were drowsy shortly before
death. Post-mortem the spleen was much enlarged in one of the
(2) Animals in which Nagana runs a Subacute Course.
Rabbits. — The duration of the incubation period noted by
Kanthack, Durham, and Blandford is about eight days. In our
experiments we frequently observed, with intravenous or subcutaneous
inoculation, that it was only two or three days.
The temperature runs a very variable course. Sometimes in
1 [C. Mathis, C. R. Soc. Biol., October 13, 1906, v. 61, p. 273.]
NAGANA • 131
cachectic rabbits, which succumb quickly, the temperature rises
when the parasites appear in the blood. In more resistant rabbits
during the eight or ten days which follow the inoculation the
temperature remains below 40° C. [104° F.]; then there is inter-
mittent fever, with irregular rises to 40° and 41° C. [104° to I05'8° F.],
rarely above 41° C. These exacerbations of temperature do not
appear necessarily to coincide with an increase in the number of the
parasites. We have sometimes seen the first rise of temperature
coincide with the appearance of oedema.
The total duration of the infection varies, according to Kanthack,
Durham, and Blandford, from thirteen to fifty-eight days (average
thirty days). It may be as long as three months (Bradford and
Plimmer). According to our observations, it varies from ten to
fifty days, not taking into account those rabbits which were wasted
at the time of inoculation.
In rabbits which survive more than twenty days certain local
symptoms occur. At first there is a little blepharo-conjunctivitis
with coryza; very soon follow cedemas, localized especially to the
head (the root of the ears more particularly), to the anal mucous
membrane, and to the external genital organs. Congestion of the
testicles or true orchitis may be present. The hair falls out around
the eyes and nose and at the root of the ears, sometimes also in
different parts of the abdornen and back. // the animal survive a long
time, these bald patches may ulcerate and exude a purulent fluid.
In these cases, too, the blepharo-conjunctivitis increases and
becomes purulent, the eyelids are stuck together, pus accumulates
beneath them, and the cornea is rapidly affected. It becomes-
opaque, and blindness may ensue. [Two rabbits inoculated by
Jakimoff died in thirteen and forty-nine days respectively ; both of
them had purulent eye lesions — conjunctivitis, keratitis, and iritis.]
In animals which succumb rapidly trypanosomes are frequently
seen on microscopical examination, but they do not become very
numerous until two or three days before death. In those cases in
which the disease runs a relatively slow course, microscopical examina-
tion may be constantly negative, but inoculation into a mouse proves
the presence of trypanosomes in the blood.
GuiNEA-PiGS. — Kanthack, Durham, and Blandford give the in-
cubation period as five to seven days. In our experiments it was
from two to four days.
Throughout the disease the guinea-pigs have continued fever with
occasional intermissions, the temperature being as a rule above
40° C. Kanthack, Durham, and Blandford's guinea-pigs died in
from 20 to 183 days (average fifty days). The disease may last
eighteen weeks (Bradford and Plimmer) ; the majority of our guinea-
pigs died in from fifteen to thirty days after subcutaneous or
intraperitoneal inoculation ; some died five or six days after, while
two survived forty-six and sixty-one days. When the disease lasts
9—2
132 TRYPANOSOMES AND THE TRYPANOSOMIASES
more than twenty days, the animal generally shows lesions of the
eyes, such as loss of hair around the eyes, and a little purulent
conjunctivitis, oedema of the vulva or sheath, and of the anus.
Except in those cases in wTiich death occurs rapidly, the number
of parasites in the blood does not increase with any regularity. On
examining the blood, parasites may be found for several days, then
they may disappear, and after some days reappear again. This may
be repeated several times. As a general rule, the parasites are more
numerous than in the blood of the rabbit, and sometimes they are
very numerous, or may even swarm for several days together. In the
two guinea-pigs which survived forty-six and sixty-one days the
parasites were seen under the microscope from the fifth to the
eleventh day after inoculation, then they were not seen again until
the last days of the disease.
FiELD-MousE. — We have experimented upon only one field-
mouse (Mus sylvaticiis), weighing 15 grammes; it proved very
resistant.
It was inoculated subcutaneously on December 21,1 902. Trypanosomes
did not appear in the blood until December 29, and were scanty until
January 10. They were very numerous from the nth to the 13th (on
the 13th there was marked tendency to agglutination) ; they were scanty
from January 13 until death (January 21). No external symptoms.
Spleen was enlarged, and weighed o'ly gramme ; the duration of the disease
was thirty days.
One may note the great difference in susceptibility between the
field-mouse and the mouse, although so closely related.
Dormouse. — We have experimented upon a dormouse {Eliomys
quercinus), which throughout the experiment was kept in the incubator
at 22° C.
From November 18, 1902 — when inoculated subcutaneously — to
December 20, the daily examination of the blood was negative.
On November 25 two drops of blood did not infect a mouse ; later
(November 30, December 6 and ig) blood inoculated in doses of 2 to
4 drops infected mice with an incubation period of four to six days.
From December 20 to January 10 trypanosomes were seen in the blood
on three occasions. The animal was very lively, and ate well ; its weight
increased from 43 to 48 grammes. From January 10 to 20 the animal
lost weight. Trypanosomes were found almost every day (always in
small numbers) on microscopic examination. There was marked weak-
ness, especially of the right side of the body. The animal was found dead
on January 21. It weighed only 30 grammes; spleen was not enlarged,
weighing o'o8 gramme. The disease lasted sixty-three days.
Equid^. — We have numerous accounts of the course of the
disease in equines, for it is these animals which are specially liable
to be attacked by the natural disease in South Africa, and, moreover,
Bruce experimented upon a certain number of them. The horse,
ass, mule, and, according to the experiments of Kanthack, Durham,
and Blandford, zebra-horse hybrids (male zebra and mare, stallion
and female zebra) and zebra-donkey hybrids (male donkey and
female zebra) are susceptible. The zebra is refractory according to
NAG AN A
133
the accounts given by explorers, but we know that animals have
often been considered refractory when really the disease runs a very
chronic course in them.^ Recent experiments of Grothusen and oi
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1 [When at Naivasha, British East Africa, I had the opportunity of examining
the blood of several zebras, which had been tamed by Mr. R. J. Stordy, P.V.O.,
but no trypanosomes were ever found. — Ed.]
I54't TRYPANOSOMES -^^^D THE TRYPANOSOMIASES
zebra to these parasites. The same thing is probably true for the
original Zululand trypanosome of nagana.
When the disease in equines is contracted as a result of the bite
of tsetse-flies, the incubation period is on an average ten days.
Kanthack, Durham, and Blandford record an incubation period of
seven days, while in the horse and donkey with which we experi-
mented the incubation period was four days. In these experimental
cases the amount of the virus injected was considerable compared
with that which even a large number of tsetse-flies can convey.
[Theiler gives three to twelve days as the incubation period.]
Fever occurs simultaneously with the appearance of trypano-
somes in the blood. It is always remittent or continued, and lasts
Fig. 20. — A Horse suffering from Nagana.
until death. In some cases there may be hyperpyrexia just before
death.
The first rise of temperature generally exceeds 41° C. [106° F.],
and may reach 42° C. [i07"6° F.], but later rises rarely exceed 41° C.
We shall see later on that various ruminants show this great initial
rise of temperature. The accompanying charts (Fig. ig) from our
experiments with a donkey and a horse show the two types of fever,
remittent and continued.
Death occurs in from fifteen days to two or three months, and
depends in great measure upon the resisting power of the animal.
Our horse, which was an old one, lived twenty-seven days, while the
donkey, which was young and active, lived fifty-nine days. The
zebra-horse and zebra-donkey hybrids succumbed in eight weeks.
[Theiler, in the Transvaal, found the disease run a very acute course
in equines— one to two weeks.]
NAG AN A 135
Equines suffering from nagana may show, during the course of
the disease, a number of characteristic symptoms as recorded by
Bruce :
' The first appearance of a horse being affected by nagana is that
his coat stares and there is a watery discharge from the eyes and
nose. Shortly afterwards a sHght swelhng under the belly or a
puffiness of the sheath may be noticed, and the animal falls off in
condition.
' The hind extremities also tend to become swollen ; and these
various swellings fluctuate, one day being marked, another day being
less marked or having disappeared. During this time the animal is
becoming more and more emaciated ; he looks dull and hangs his
head ; his coat still stares, becoming harsh and thin in places ; the
mucous membranes of the eyes and gums are pale, and probably a
slight milkiness of the cornea of the eyes is observable. In severe
cases and in the last stages a horse presents a miserable appearance.
He is a mere scarecrow covered with rough harsh hair, which has
fallen off in places. His hind extremities and sheath may be more
or less swollen, sometimes to a great extent, and he may have
become quite blind. At last he falls down unable to rise, his
breathing becomes shallower and shallower, and he dies of exhaus-
tion. During his illness he has shown no symptoms of pain, and up
to the last day has had a fairly good appetite.'
Our two animals did not show all these symptoms. The horse
had great oedema of the whole of the ventral region, as shown in
Fig. 20. The ass had no cedema, but during the last three weeks of
its life it was profoundly lethargic, which was commented upon by
all who saw the animal.
We have mentioned the coincidence of the appearance of trypano-
somes in the blood and the first febrile paroxysm. Our charts show
better than any description the striking parallel between the curve
of the temperature and that of the parasites in the blood.^ Trypano-
somes could be found almost every day on microscopic examination,
but they were never very numerous. The red corpuscles gradually
diminished, and at the time of death were reduced to one half their
original number or even less.
Pig. — We showed, at the same time as Plimmer and Bradford,
the great susceptibility of the pig to nagana.^ We shall here merely
1 This parallelism is particularly well seen in the case of the ass. One notes
the great regularity with which the maximum number of trypanosomes occurs
at intervals of about seven days ; also the striking parallel (much more marked
than in the case of the horse) between the temperature curve and that of the
parasites. It should be noted that the maximum number of parasites generally
preceded the maximum temperatures by twenty-four hours. The disappearance
of the parasites during the last four days of the illness is probably due to two
injections of sodium arsenite.
2 [Bradford and Plimmer state {/oc. cit., p. 462) : ' The pig shows the organism
in the blood very rarely and in very small numbers, and dies with pulmonary
symptoms.' Nocht and Mayer, in Kolle and Wassermann's ' Handbuch der
pathogenen Mikro-organismen,' state that the pig is fairly resistant. Schilling
and Martini also found that the pig is not very susceptible to the Togo virus.]
136 TRYPANOSOMES AND THE TRYPANOSOMIASES
refer to the case of the young pig which we inoculated, and which
died ninety- four days later (see detailed account in Bull. Acad.
Med., January, 1902). Its temperature fluctuated between 39-5°
and 40-5° C. [103° and 105° F.] (which is a little higher than the
normal temperature of a young pig), except during the last few days
of life.
During the first forty days the animal showed no symptoms, but
gained steadily in weight. Trypanosomes were never found in the
blood on microscopic examination, but a few drops of the blood
inoculated intraperitoneally into a mouse always infected it. About
the fortieth day there was marked weakness of the limbs. This
weakness rapidly increased, and soon the animal was no longer able
to stand. Its anterior extremities, which were constantly bent,
became oedematous and ulcerated at the knees. There was marked
arching of the back at the level of the lower dorsal vertebrae.
During the last month the animal lay either on its belly or on its
side, and it was necessarj^ to support it in order that it might eat.
The left cornea became opaque. During the last three days the
temperature fell, and was markedly subnormal when the animal
died. Two days before death the microscopic examination of the
blood was positive -for the first time. On the day of death trypano-
somes were numerous.
Lignieres,^ at Buenos Ayres, infected two pigs, one of which was
immunized against caderas. At the end of fifteen days and of one
month the blood of the two pigs was virulent ; after two months the
blood of the pig immunized against caderas was no longer virulent ;
after three months the blood of the other pig was also non-virulent.
These two animals, therefore, made a rapid recovery.
(3) Animals in which Nag"ana runs a Chronic Course,
BoviDiE. — ' There is,' says Bruce, ' a great difference in the
duration of the disease in cattle : a few will die within a week of
taking the disease, many die within a month, and others linger on
for six months or longer. The general opinion among the traders
and natives in Zululand is that only a very small percentage recover.
' The general symptoms in cattle are less marked than in horses
and dogs. They gradually waste away ; the hair, at first harsh and
staring, tends to fall off; there is the same trickling of a watery fluid
from the eyes and nose, and a tendency to diarrhcea, which, however,
I have never found marked. In many cases the dewlap becomes
swollen and baggy, but I have not found the same tendency to the
swelling of the under surface of the belly or the extremities as in the
other animals, nor have I ever seen blindness occur in cattle. The
hsematozoa are also much less numerous in the blood of cattle than
in that of horses and dogs, and often require to be looked for on
several days in succession before they can be demonstrated.'
1 J. Ligniferes, Bo/, de Ai^Tic. y Gaiiad., third year. No. 50, February i, 1903.
NAG AN A
137
The fever, which is continued, is less marked than in horses,
bearing in mind the higher normal temperature of cattle (about
38'4° C. or 101° F.), but the temperature sometimes rises above
41° C. [105-8° F.]. _
The accompanying chart, taken from Bruce's paper, gives an
idea of the course of the temperature and of the number of trypano-
somes. In this case the number of red corpuscles diminished from
5,260,000 to 1,800,000 per cubic millimetre. When death occurs
more rapidly the diminution is less marked.
At Alfort, Nocard inoculated several Breton cows subcutaneously.
They all survived, and ■ exhibited only the slightest symptoms of
ill-health. There was a rise of temperature above 40° C. five days
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WITH Nagana (after Bruce).
As it was a case of spontaneous infection, the curves start from tlie day on which the
disease was recognised. The normal temperature of the cow is about 101-4° F-
after inoculation, and on that day a few trypanosomes were visible
in the blood. Two days later the temperature was normal, and
remained so until the end of the infection. The general condition
of the animals was good. Microscopical examination of the blood
was always negative, but the blood remained infective for mice for
five months. At the end of that time the blood was no longer
infective, and the cow was immunized against nagana.
Is this marked resistance of Breton cows to trypanosomes a
question of race, or is it due to the fact that the virus injected had,
through long disuse with cattle, lost its virulence for them ? Further
experiments are necessary in order to decide this point. We may
note that Argentine cattle are also only slightly susceptible to our
virus (Lignieres).
Nocard introduced infective blood (2 c.c. of rat's blood rich in
trypanosomes) into the teat of a cow which had recently calved.
138 TRYPANOSOMES AND THE TRYPANOSOMIASES
This did not infect the animal, nor was there any fever, mastitis,
or alteration of the milk.
Sheep and Goats. — According to Bruce, the native goats and
sheep of South Africa are less susceptible than other mammals, the
disease as a rille running a chronic course and lasting five months.
In Bradford and Plimmer's experiments a goat died in two months.
Nocard has given us a complete account of the disease in a sheep
which died in six and a half months (197 days). The animal had on
the sixth day after inoculation a rise of temperature to 41° C, after
which it fell to between 39° and 40° C. On the twenty-fourth day
it rose again to 4i'5° C. [io6-8° F.], and remained for a considerable
time at about 41° C. There was oedema of the face and eyes, then
of the testicles. It was only during this period that trypanosomes
could be found on microscopical examination, and for about a week
several could be found in each field of the microscope. The
swellings increased, and extended as far as the hind quarters and
shoulder by the end of the third month, after which they
rapidly disappeared. During the fourth, fifth, and first half of the
sixth months, the animal had apparently recovered ; its temperature
was about 39° or 40° C, but its blood was still infective. During
the last month it wasted rapidly, and after death there were found
signs of profound cachexia, and gelatinous exudation about the
throat, pericardium, and pleurae.
Some of our sheep died after infection with nagana without
showing any local symptoms, but as they were all somewhat
cachectic, it is possible that nagana was not the sole cause of death.
On the other hand, two of our sheep recovered. One of them was
carefully watched from day to day ; its history was as follows :
The infection lasted six to seven months. The disease started
two days after inoculation with a rise of temperature, which on the third
day reached 4i'5° C. [io6-8° F.]i; on the same day trypanosomes were
seen on microscopic examination, but this was the only day on which the
microscopical examination was positive.
For the next four months the temperature remained high, with several
rises to 41° C, and the animal wasted considerably. At first the blood
was almost always virulent for the mouse in doses of a few drops ; the
incubation period for the mouse was four to eight days, so that the
trypanosomes inoculated must have been very few. During the fourth
month the blood was no longer infective in doses of i c.c, but it became
infective again later. The fifth month, although trypanosomes were still
present in the blood, and the temperature was considerably raised (about
40° C._), the sheep gained in weight. At the end of the sixth month its
condition improved, the temperature coming down to 39° C, and the
blood became gradually less infective, so that sometimes there was
not a single trypanosome in i c.c. At the end of the seventh month
5 c.c. of blood failed to infect two rats, so that the animal may be con-
sidered cured. It was immunized. During the six and a half months
that the disease lasted the animal did not show the least sign of
oedema.
' This great rise during- the first week occurred with all our goats and sheep.
NAG AN A 139
Lignieres, working with our virus, found that Argentine sheep
tecome infected, but recovered in less than three months.
Bradford and Plimmer's goat which died in two months had
■cedema of the genital organs and opacity of the eyes.
We have inoculated a nanny goat and a billy goat. The billy goat
succumbed very rapidly after a severe infection, but we cannot say
with certainty whether death resulted from the infection or was due
to sonje other unknown cause.
The history of the nanny goat is particularly interesting, as it
furnishes a proof of the non-identity of nagana, caderas, surra, and
the Gambian horse disease. The goat ended finally by succumbing
to the last-named infection. We append a short account of the
nagana infection in this goat.
Nanny goat, weighing 24J kilogrammes, inoculated October 25, 1901,
with the blood of a mouse with nagana. A very mild infection followed,
the symptoms being fever (rises to 41° C), wasting (the weight fell to
20 kilogrammes), and the presence of trypanosomes in the blood. The
parasites were always very scanty ; they could be seen on examining the
blood only on October 28 and 29, and then only in very small numbers.
Afterwards, in order to demonstrate their presence, it was necessary to
inoculate the blood into a rat or a mouse. In November or December
two or three drops of blood were sufficient. On January 31 and February 6,
igo2, I c.c. of blood was no longer infective. Animals inoculated on
February 24 and March 10 with f and 2 c.c. of blood respectively con-
tracted the infection.
From April r injections of the goat's blood failed to produce an infec-
tion, in spite of large doses (up to 3 c.c), and of the fact that the goat was
frequently reinjected with blood containing many trypanosomes. Its
cure and its immunity from nagana were established.
On April 23 the goat was inoculated subcutaneously with i c.c. of
diluted blood from a mouse. From May 8 to October 4 it received in all
fifteen injections of blood from infected dogs. On one occasion 60 c.c. of
blood was injected ; frequently the dose was 50 c.c, and altogether the
goat received 500 c.c. of infective blood. During July and August
inoculations were few and far between, the reason being that the goat had
a very large abscess, which took a long time to heal.
Later on we shall come across this goat again in connection with
other trypanosomiases. (Goat I.). Here we may just mention that
the animal was still immune against nagana in May, 1903, after
having recovered from an infection of caderas, and in December, 1903,
after having recovered from an infection of surra.
Many other ruminants are susceptible to nagana. Thus Plimmer
and Bradford have seen a springbok {Antidorcas euchore) succumb at
the end of four weeks, after having shown parasites in its blood
and having exhibited nervous symptoms. The duration of the
disease was remarkably rapid if it were due entirely to the virus
inoculated.
The wild ruminants of Zululand are susceptible to nagana, as
shown by Bruce's experiments, about which we shall speak in the
paragraph on propagation. Bruce infected dogs with nagana by
140 TRYPANOSOMES AND THE TRYPANOSOMIASES
inoculating them with blood from the African buffalo and various
Zululand antelopes : Tragelaphus scriptus sylvaticus (bushbuck),
Catoblepas gnu (wildebeest), Strepsiceros capensis (koodoo). These
animals had been hunted and shot, and trypanosomes were never
visible in their blood on microscopic examination. It is, therefore,
probable that, although they have T. brucci in their blood, the
disease in them is extremely mild.^
There is a belief, very prevalent amongst explorers and sportsmen,
that animals born in the ' fly country ' are much less susceptible
than animals of the same species which are imported, and this is
said to apply not only to ruminants, but also to horses and dogs.
[Geese. — Until Schilling,^ in 1904, succeeded in infecting geese
with the Togo virus, all authors, with the exception of Voges, were
agreed that birds were refractory to the pathogenic mammalian
trypanosomes. Schilling's positive results were obtained with the
Togo virus, and will be considered more fully in the section dealing
with the Togo trypanosomiases. Mesnil and Martin^ repeated these
observations on geese and fowls, using the following trypanosomes :
(i) T. brucei (Zululand strain) ; (2) T. evansi (Indian) ; and (3) T. equinum
(caderas). One goose inoculated with T. brucei became mildly
infected — the infection lasting about three months, and resulting in
the immunity of the bird — but all the other experiments yielded
negative results. In the only positive experiment, the trypanosomes
were never found on microscopical examination of the blood, but
the blood was infective for guinea-pigs.]
[Goebel* has recently succeeded in infecting fowls with the
Zululand T. brucei by injecting 2 c.c. doses of virulent guinea-pig
blood. The fowls never showed trypanosomes in blood-films, but
the blood was virulent for guinea-pigs as long as fifty-five days after
the birds were inoculated. The fowls became immunized, and when
their blood was no longer infective, reinjection failed to reinfect.]
Section 2. — Patholog-ieal Anatomy.
Nagana is one of those diseases in which very few lesions are found
post-mortem. Most authors mention hypertrophy of the spleen as
the only constant lesion. It is always present in rats, mice,^ and
dogs,'' but is rather rare in guinea-pigs and rabbits. According to
Bruce, it is equally present in the larger domestic animals. As a
1 Compare the susceptibility of the buffalo to the trypanosome of Togo noted
by Martini (second part of this chapter).
^ [Schilling, Ari. a. d. kaiserl. Gesund., v. 21, pp. 476-536.]
^ [Mesnil and Martin, C. R. Hoc. Biol., v. 60, 1906, p. 739.]
* [Goebel, C. Ji. Sac. Biol., v. 61, 1906, p. 321.]
^ The spleen of a normal mouse is about ^J^y of its weight (7 centigrammes in
a mouse weighing 20 grammes) ; that of a mouse which has died of nagana
is "I Jo of its weight. It is, therefore, increased threefold. The spleen of a rat with,
nagana is very variable in weight : sometimes its weight is trebled, at other times
it is increased tenfold.
" The normal spleen of a dog is about ^Jfj of its weight. In a dog with nagana
it is sometimes doubled, in others quadrupled in weight.
NAG AN A 141
general rule, we may say that enlargement of the spleen is most
marked in those animals which have shown a very large number of
trypanosomes in their blood during life. [Occasionally in guinea-
pigs the enlarged spleen may become so soft that it ruptures, either
spontaneously or as the result of the animal being handled.]^ In the
rat hypertrophy is due to congestion of the organ, no appreciable
histological changes being visible on microscopical examination. ,
In smears of the spleen and liver, the numerous parasites present
are often deformed, if the autopsy has not been made immediately
after death. The parasites are often arranged in groups suggesting
reproduction forms.
Kanthack, Durham, and Blandford, and Plimmer and Bradford,
have drawn particular attention to the enlargement of the lymphatic
glands, especially of those nearest to the site of inoculation.
This hypertrophy is indeed marked, but, contrary to the opinion
of the two last-named authors, it does not appear to us to be
associated with a considerable multiplication of the parasites in situ :
as a matter of fact, they are rather scanty in the glands.
In a spleenless rat which died of nagana the lymphatic glands
on the side inoculated were considerably enlarged, but not more so
than those of a control rat with nagana. It is said that animals
which become infected by eating virulent material always show
enlargement of the glands in the region of the head or neck, which
proves — so say these authors — that the infection first enters the
system through an abrasion of the mouth or nostrils. At the
autopsy on horses which have died of nagana hypertrophy of the
spleen and liver, yellowish gelatinous infiltrations under the skin and
mucous membranes and between the muscles, pleural and pericardial
exudations, and subpericardial ecchymoses are found.
At the autopsy on our horse, made eleven hours after death, the
lesions were insignificant. The spleen did not appear enlarged
(weight = 3,i5o grammes), but its surface was uneven and covered
with dark brown mottling ; 200 c.c. of pale red fluid was present in
the pleural cavities, and 150 c.c. in the pericardium, both containing
a few trypanosomes. There were some ecchymoses under the
pericardium and endocardium ; the myocardium and all the other
organs were normal.
[Martini made the interesting observation that the cerebro-spinal
fluid may be increased in equines dying of tsetse-fly disease, and that
many trypanosomes may be found in the cerebro-spinal fluid
immediately after death. In this respect, as well as in the typical
bent attitude, the tsetse-fly disease of the horse and donkey resembles
human trypanosomiasis (sleeping sickness). Martini also found
trypanosomes in the fluid in the anterior chamber of the eye in
animals with corneal opacity (dog, cat, rabbit). Jakimoff found
1 [Laveran and Mesnil, Markl, Nabarro and Stevenson, and Sauerbeck have
seen this happen.]
IJ2 TRYPANOSOMES AND THE TRYPANOSOMIASES
several of the body fluids of experimental animals infective ort
inoculation — the cerebro - spinal fluid, pleural, pericardial, and
peritoneal exudations, bile, and subcutaneous oedema fluid. The
urine was not infective.]
At the post-mortem on the young pig which died of nagana after
showing very marked paralytic symptoms we found the following
condition present. The bones of the spinal column were softened
so that the vertebrse could easily be cut with a knife. This
softening of the skeleton, a true osteomalacia, explains how, under
the influence of the paralysis and of the faulty position of the hind
limbs which followed it, a very marked arching of the back in the
dorsal region was produced. The lower part of the spinal cord was
surrounded by a gelatinous exudate, a partially coagulated serous
effusion analogous to that found in the pericardium and subcutaneous
tissue, but there was no spinal meningitis. The spinal cord removed
in its entirety and carefully examined did not show any macroscopic
changes — there were no patches of softening. The medulla
oblongata, cerebrum, and cerebellum appeared normal. The spleen
was not enlarged. There were 20 c.c. of straw-coloured fluid present
in the pericardium, and a little in the pleural and peritoneal cavities.
Finally, we may note that from the time an infected animal dies,
and sometimes even during the agony, the trypanosomes which it
contains diminish in vitality. Twenty - four hours after death,
especially in small animals, there are no longer any active parasites
in the blood or internal organs. They may, however, be present in
very small numbers, for the blood is sometimes still virulent.
[Since 1904, numerous investigations have been carried out on the
changes produced in the blood, and on the microscopical appearances
seen in the various organs of animals infected with nagana. Amongst
those dealing with the blood changes may be mentioned the
researches of Goebel and Demoor,^ Markl,^ Massaglia,^ Mayer,*
Nissle,^ Sauerbeck,^ and Jakimoff.'' The papers dealing with the
pathological histology of, and the distribution of trypanosomes in, the
internal organs are those of Baldwin,* van Durme,^ Halberstaedter,^*
' [O. Goebel and A. Demoor, Ann. Soc. de Med. de Gand, 1906, pp. 137-148.
See also Mesnil, abstract in Bull. Inst. Past., 1906, v. 4, p. 667.]
- [Markl, Centralb.f. Bakter., I, Orig., v. 37, p. 530.]
3 [A. Massaglia, Boll. R. Accad. med. di Genova, 21st year, No. I., 1904 ; see
abstract by Mesnil, Bull. Inst. Past., v. 4, 1906, pp. 667, 668.]
* [Mayer, Zeitschr. f. Path. ti. Ther., v. I, l_905.]
5 [Nissle, Arch.f. Hyg., v. 53, 1905, pp. 181-204 ; and v. 54, 1905, pp. 343-353.]
" [Sauerbeck, Zeitschr. f. Hyg. u. Infektions., v. 52, [905, pp. 31-86 ; see also
abstract by Mesnil, Bull. Inst. Past., v. 4, 1906, pp. 317, 318. In the Ergebn. d.
allgem. Path. u. pathol. Anat. des Menschen. u. der Tiere, v. 10, 1906, pp. 305-
379, Sauerbeck gives a long r&umd of our knowledge of the trypanosomes, as well
as an extensive bibliography.]
'■ [W. L. Jakimoff, Centralb. f. Bakter., I, Ref., v. 38, 1906, pp. 13-16.]
*■ 'Baldwin, _/oz/r«. Infec. Dis., v. I, 1904, pp. 544-550.]
" [Van Durme, An7i. Soc. de Med. de Gand, 1905, p. 231 ; Arch, de Parasit.,
V. 10, 1906, p. 160.]
1" [Halberstaedter, Centralb.f. Bakter., I, Orig., v. 38, 1905, pp. 525-532.]
NAG AN A 145
Massaglia,"^ Neporojny and Jakimoff,^ Prowazek,' Rodet and Vallet,*
and Sauerbeck^].
[Blood-Changes. — Coincident with the first appearance of the
trypanosomes in the blood and with their multiplication in it, there
is a diminution in the number of the red blood-corpuscles, which in
extreme cases may fall to one-third of the original number. As a
rule, the corpuscles themselves look normal, but Nissle has described
various pathological changes in them (alterations in shape, poly-
chromatophilia), and also very varied endocorpuscular forms of the
parasite. These, he says, are to be seen in the blood when the
trypanosomes are undergoing destruction either spontaneously or as
the result of injections (B. prodigiosus, trypanred, etc.)]
[The leucocytes are always increased, but Goebel and Demoor
state that at the outset there is a marked leucopenia. At first the
polymorphonuclears are increased and the mononuclears relatively
diminished, but soon the polymorphonuclears are diminished (from
78'5 to 38 per cent, in a dog, Jakimoff), and the mononuclears are
increased (15 to 48 per cent, in the same dog, Jakimoff). There is
no eosinophilia.]
[Jakimoff found that the alkalinity of the blood is diminished in
dogs infected with nagana, caderas, and dourine. Martini found
that the blood of nagana animals is diminished in coagulability.
The blood-proteids undergo the same changes as in bacterial
infections, the ratio of albumin to total globulins falling from i"5, or
2 to I (Mayer). At death there may be lipasmia (Massaglia), as
Mayer has also shown in the cases of dogs with caderas.]
[The Distribution of the Trypanosomes in the Body. — As
we have already seen, the trypanosomes, once they appear in the
blood, may steadily and progressively increase in number until death
■ — as in rats and mice ; or they may be present in large and small
numbers alternately, being sometimes very numerous and at other
times very scanty, or even absent in blood-films — as in guinea-pigs ;
or the parasites may be very scanty in the blood throughout the
infection, except, perhaps, just before death — as in rabbits. During
the remission stage (in the guinea-pig) Goebel and Demoor found
the trypanosomes fairly numerous in the lymphatic glands, and very
abundant in the testicles, but none could be found in the other organs.]
[Van Durme, who examined the blood and freshly teased-up
organs of rabbits killed at varying intervals after the onset of the
infection, found that the parasite multiplies first at the site of
inoculation. Thus, after intraperitoneal inoculation, trypanosomes
are present for ten days in the peritoneum. Soon after there is an
increase in the blood, and it is at this stage of the onset that the
' [See references on p. 142.]
^ [Neporojny and Jakimoff, Centralb.f. Bakter., I, Ref , v. 35, 1904, pp. 467, 458.].
2 [Prowazek, Arb. a. d. kaiserl. Gesund., v. 22, 1905 ; see abstract b)' Mesnil,,
Bull. Inst. Past., v. 3, 1905, pp. 553, 554.]
* [Rodet and Vallet, A^ch. mfd. expdr., v. 18, July, 1906, p. 450-494.]
144 TRYPANOSOMES AND THE TRYPANOSOMIASES
parasites are most numerous in the blood. Shortly after this they
are found in the testicles, which explains the orchitis and other
lesions of the genitalia so commonly seen in rabbits. The glands
are next infected, then the conjunctiva, the skin in the region of the
oedematous swellings, and the nasal mucous membrane. In all
these organs and tissues the number of trypanosomes increases
progressively and then diminishes, pari passu with the well-known
clinical affections shown by them. The order given by van Durme
corresponds almost exactly with the order of the clinical symptoms.
The secretions (semen, conjunctival pus) are free. The spleen,
salivary glands, liver, kidneys, suprarenal capsules, lungs, brain and
spinal cord, lachrymal and thyroid glands, thymus, bone-marrow,
and ovary were always negative (except once in the case of the first
two). In the rabbit, therefore, T. brucei may be more abundant in
certain organs than in the blood, and these organs are precisely those
which present functional derangements and macroscopic lesions.^]
[Halberstaedter obtained somewhat similar results in his rabbits,
except that he never found trypanosomes in the testicle. In the cedema-
tous swellings about the eyes and nose, trypanosomes were found in the
altered skin cells and between the cells under the epithelium, as well as
down in the subcutaneous tissues, but never in the bloodvessels. In
mice, on the other hand, he found trypanosomes in all the bloodvessels in
the internal organs, especially the liver, and in the skin.]
[In other animals Prowazek and Neporojny and Jakimoff found
masses of parasites, causing capillary embolism in the brain, lungs, and
liver.]
[Nabarro and Greig, in Uganda, nearly always found subserous
petechial haemorrhages (pleural, pericardial, and endocardial) in their
experimental animals (monkeys, dogs, guinea-pigs) dying of various
animal trypanosomiases. Smears of these petechise usually contained
masses of trypanosomes (many more than were present in the blood of
the animal), which led these observers to conclude that the petechias were
really embolic areas, the emboli being the masses of the parasites. ^J
[The Place and the Mode of Destruction of Trypanosomes. —
Most authorities are agreed that trypanosomes are destroyed by the
phagocytic action of various cells.]
[Prowazek found all stages of destruction of the parasites in the poly-
morphonuclears (and exceptionally in the eosinophiles), as well as in the
mononuclears.]
[Sauerbeck, working with rats, guinea-pigs, rabbits, and dogs, could
not find any degenerating forms in the blood, but saw them easily in the
internal organs, especially in the spleen, lymphatic glands, bone-marrow,
liver, and, !o a less extent, in the lungs. These involution forms, ^ Sauer-
^ [The above account is taken from Mesnil's abstract in Bu^. Inst. Past., v. 4,
1906.]
2 [They made a somewhat analogous observation in the case of dogs dying of
piroplasmosis. These animals also showed petechial haemorrhages, especially
under the pleura, and smears of these areas showed many more infected red
corpuscles and more parasites in the corpuscles (8 to 10 were sometimes seen),
than did the peripheral blood-films.]
^ [Sauerbeck draws attention to the similarity of the commonest involution
forms to the Leishman body, but this morphological resemblance is not sufficient
to warrant our putting the trypanosomiases and tropical splenomegaly in the same
category, as Sauerbeck,- Marchand, and others would do. See Mesnil's abstract in
Bull. Inst. Past., v. 4, 1906, pp. 317, 318.]
NAG AN A 145
beck thinks, explain the so-called amceboid and plasmodial forms of
Bradford and Plimmer. The involution forms of trypanosomes in the
organs are, as a rule, intracellular. The hypertrophy and the histological
changes in the organs are due to a phagocytic proliferation. In the
lymphatic glands it is the cells of the lymphoid tissue which destroy the
trypanosomes ; in the spleen, the cells of the pulp and, to a less degree,
those of the follicles ; in the bone-marrow, the medullary cells ; in the
liver — unlike the foregoing organs — it is the endothelial cells of the capillaries ;
and, lastly, in the lungs, the alveolar epithelium. The cells concerned
become very large and amceboid. In them one or more degenerating
trypanosomes, easily recognisable in the form of Leishman's bodies, may
be found ; but often there are only remnants, or even only empty vacuoles,
doubtless marking the place where a parasite has been digested. The
cellular hypertrophy is followed by hypersemia of the phagocytic organ,
and the two together give rise to enlargement of the organ. Secondarily
there are thromboses and catarrhal desquamation of the lungs.^]
[Rodet and Vallet,^ on the other hand, ascribe the extensive destruc-
tion of trypanosomes in the spleen to an extracellular trypanolysis. The
method they employed — that of making smears — is not a good one
(Mesnil), as many intracellular parasites may become liberated thereby.]
[It has been found that injection of a culture of B. prodigiosus
(Nissle) or an intercurrent microbic infection, as with streptococci
(Massaglia), causes a rapid disappearance of the trypanosomes from
the blood. It is possible that the scarcity of trypanosomes in the
blood of patients in the later stages of human trypanosomiasis
(sleeping sickness) is also due to the concomitant bacterial infection,
which is frequently present as a terminal phenomenon.]
[Changes in the Organs. — Microscopic changes have been described
in several of the tissues and organs.]
[Baldwin found the spleen most affected. Microscopically there were
congestion accompanied by hyperplasia of the reticulum of the pulp, and
a variable degree of hyperplasia of the cells resembling the myelocytes
seen in the blood in certain diseases. There were also present some red
blood-corpuscles and giant cells like those of the bone-marrow. The
myelocyte-like cells and the giant cells could be seen de^'eloping from
endothelial cells of the pulp. There was also an abundant deposit of the
iron-containing pigment, haemosiderin, which Baldwin suggests is formed
by a haemolytic action of a soluble toxin of the trypanosomes. The other
haematopoietic organs, the glands, and the bone-marrow also showed
hyperplasia. The lungs were engorged, and the alveoli often contained
desquamated epithelial cells and granular exudate.]
[Neporojny and Jakimoff found the spleen enlarged in all their animals.
Microscopically some Malpighian bodies were enlarged, and others were
undergoing degenerative changes. The lymphatic glands were enlarged
in chronic cases, and in such cases the bone-marrow was red. The lungs
showed considerable microscopic changes, the capillaries being filled with
trypanosomes, and sometimes even the larger vessels were thrombosed
from the same cause. The kidneys and the liver showed the most marked
changes. In the former there was congestion of the cortex, often with
^ [This catarrhal desquamation of the lungs may explain why catarrhal
pneumonia is so frequently a terminal phenomenon in human and several
animal trypanosomiases.]
'' [A. Rodet and G. Vallet, C. R, Acad. Sciences, v. 142, 1906, pp. 1229-1231 ;
also Arch. m^d. exper., July, 1906.]
10
146 TRYPANOSOMES AND THE TRYPANOSOMIASES
petechial haemorrhages, which microscopically were found to have their
seat in the glomeruli. The authors think that this lesion of the kidneys
explains the fact that Jakimoff constantly found albumin in the urine of
infected animals, and they make the suggestion that possibly the frequent
cedemas, fits, and drowsiness seen clinically are ursemic in origin.]
[The liver is usually enlarged and finely granular on the surface. The
changes in it seem to occur as follows : Owing to masses of trypanosomes
in the capillaries, the blood-flow is sluggish, and in places completely
stopped. As a result, degenerative changes take place, with atrophy,
fatty degeneration, necrosis, and karyolysis of the liver cells and of the
capillary endothelium. Around these degenerating areas are zones of
inflammatory reaction with karyokinetic figures in the liver cells and in the
endothelial cells. The latter are definitely phagocytic, engulfing and
digesting trypanosomes and leucocytes.]
[Halberstaedter, on examining the characteristic testicular swellings in
rabbits, found a marked round-cell infiltration between the tubules ; the
epithelium of the latter was degenerating, but no trypanosomes were seen.]
[Massaglia always found the kidneys most affected, and in a condition
of subacute hgemorrhagic parenchymatous nephritis, with marked degenera-
tion of the epithelium of the tubules. The liver showed subacute hepatitis
with fatty degeneration ; the spleen, lymphatic glands, and bone-marrow
showed lesions similar to those already described.]
Section 3.— Resume of Symptoms and Patholog-ical Anatomy.
The variations in the symptoms and course of nagana in
different species of animals will be clearly seen from the following
accounts.
If we were not acquainted with the pathogenic agent it would
be difficult to believe that the very varied conditions produced by
T. briicei in the rat and mouse, in the horse, pig, ox, and goat,
were due to the same disease. We have seen that nagana may
sometimes occur as an acute or subacute disease which is always
fatal, sometimes as a chronic disease which may end in recovery.
Amongst the most constant symptoms should be mentioned
fever, anaemia, and cedema, but here again there are great variations
in the different species of animals.
In rats there is no fever or oedema, even when, by means of
appropriate treatment {vide infra), the life of these animals is
prolonged for two months or more. In the rabbit the febrile
paroxysms are very irregular. In the guinea-pig and .dog the fever
is often of a continued type, with more or less marked morning
remissions. The horses and cattle of Zululand suffer from remittent
fever during the whole course of the disease. In European cattle,
after an initial rise, the temperature falls to normal and remains so.
In the dog the temperature is usually raised until death occurs.
Other animals, such as the pig and monkey, die with a subnormal
temperature. In the monkey, the account of which we have given
above, the temperature fell below normal several days before death,
and on the day the animal died the rectal temperature had fallen to
28-5° C. [83-4° F.].
The cedematous swellings, which are usually very marked in the
NAG AN A 147
rabbit and horse, are less marked or entirely absent in the guinea-
pig, dog, sheep, and goat. Blepharo-conjunctivitis, coryza, ulcerations
of the skin, and partial loss of hair, are common symptoms in the
rabbit, but rare in other animals. Opacity of the cornea is seen in
certain species of animals and not in others. In the horse and
donkey, and sometimes in dogs, there is paresis of the posterior
extremities towards the end of the disease. The pig with which we
experimented had almost complete paralysis of all four limbs and
osteomalacia. Rats often die suddenly with convulsions ; this mode
of death is much rarer in the mouse, and has not been observed in
any other species of animal.
The way in which the trypanosomes multiply in the blood also
varies considerably.
In the mouse and rat they increase rapidly and regularly, so
that at the time of death the number of parasites may be at least
equal to that of the red corpuscles. In the dog and monkey
the trypanosomes multiply fairly rapidly, but less regularly than
in rodents, and rarely to so great an extent. In the rabbit
trypanosomes are almost always scanty, even at the time of
death. In the guinea-pig there is no regular increase in the
number of the trypanosomes. In equines the curve of the trypano-
somes shows great oscillations, almost parallel with those of the
temperature. In the pig trypanosomes are so scanty that they are
not found on microscopical examination, and it is only during the
last days of the disease, when the temperature is subnormal, that
the parasites multiply in the blood. In the cow, sheep, and goat,
especially in our experiments, the trypanosomes are nearly always so
scanty that it is necessary to inoculate susceptible animals to show
that the blood is infective.
The pathological anatomy of the disease also differs in different
animals ; thus splenic hypertrophy, which is constant and well
marked in rats and mice, is very generally absent in rabbits.
Why does nagana present such variable symptoms in different
animal species ?
There are evidently many factors which may increase or diminish
the virulence of T. brucei. The facts we have adduced above suggest
that the virulence of T. brucei for rodents has increased as the result
of numerous passages through these animals which, in preference to
others, are used in laboratories for the preservation of the parasite,
and that at the same time the virulence has diminished for other
species — Bovidae, for example.
The virulence of trypanosomes may be somewhat attenuated by
passage through different species. We have quoted instances of
this — e.g., nagana in mice, rats, and dogs, produced by a trypano-
some which had been for a long time in the pig or the sheep ; but
T. brucei readily adapts itself to its new conditions in passing from
one species to another, and in all cases it rapidly regains its natural
10 — 2
148 TRYPANOSOMES AND THE TRYPANOSOMIASES
virulence. We shall return to this subject in the paragraph upon
immunization.
The trypanosome of nagana evidently finds the blood of certam
animal species a more favourable medium for its multiplication than
the blood of other species; but this explanation merely alters the
form of the question. Why is the blood of certain mammals a
better medium for T. brucei than that of other mammals ?
The temperature of the animal seems to play a part. The
trypanosome of nagana cannot withstand long exposures to a
temperature of 40° to 41° C. in vitro, and no doubt the same thing
is true in vivo.
When the temperature of an infected animal is raised (40° to
41° C), the trypanosomes are seen to diminish in number, and when
the temperature falls, the parasites begin to multiply again in the
blood. This explains the almost parallel oscillations, in the Equidffi,
of the number of trypanosomes and of the temperature ; after the
febrile paroxysms the curve of the trypanosomes falls.
In the young pig of which an account has already been given
the effect of temperature is evident. The pig had a normal rectal
temperature of 40° C, and during the whole of the disease the
trypanosomes were so scanty that they could not be seen on
microscopic examination, but some days before death the temperature
fell, and at the same time the trypanosomes multiplied in the blood.
The high temperature of birds appears to play an important
part in rendering them refractory to nagana ; [but, as we have
seen, Schilling, Mesnil and Martin, and Goebel have succeeded in
infecting geese and fowls, so we can no longer consider birds
absolutely refractory to mammalian trypanosomes].
The effect of temperature upon T. hnicei only partially explains
the facts ; it is certain that other factors help to modify the course
of nagana.
Human serum injected into infected animals causes the trypano-
somes to disappear, at least for a time, and this property of human
serum no doubt depends upon the natural immunity of man against
nagana. One may ask whether the leucocytes of certain animals do
not contain a substance analogous to that which gives to human
serum its remarkable properties, but in too small a quantity to
give the serum of these animals an action upon T. brucei com-
parable with that of human serum.
How does the T. hrucei act ? An infection so intense as that
found at the moment of death in rats, mice, and certain other
animals, leads to the natural supposition that such an enormous
number of parasites must produce serious and even fatal effects upon
the general nutrition. But we must not forget that rats infected with
T. lewisi may also have a very large number of parasites in their
blood without apparently suffering any inconvenience. And, more-
over, in the experiments on treatment with arsenic, of which we
NAG AN A 149
shall speak later, rats have lived for more than a fortnight with
almost as many trypanosomes as red blood-corpuscles in their blood.
In animals which survive for a considerable time there is marked
anaemia, but it is never sufficiently pronounced to be the sole cause
of death. [Jakimoff also thinks that the blood-changes found by him
are not sufficient to account for the fatal issue. He says death may
be due to a number of causes : (i) Well-marked histological changes
in all the parenchymatous organs and plugging of the capillaries
with trypanosomes ; (2) poisoning by the toxins of the trypano-
somes ; (3) oligocythsemia ; and (4) uraemia, for during the disease
he always found albumin in the urine.]
The trypanosomes, when they occur in very large numbers in the
blood (as in the last stage of the disease in rats and mice), may act
mechanically by plugging the small vessels of the brain or bulb. In
this way is probably to be explained the rapid death, accompanied by
convulsive movements, which is common in rats. But this is not
always the case,^ and moreover, in many animals which die of
nagana trypanosomes may be very scanty during the whole course
of the disease, as, for instance, in the rabbit. Consequently one is
almost forced to admit that the trypanosomes produce a toxin
which gives rise to the febrile paroxysms, the pareses, the disorders
of nutrition, the apathetic condition, and finally death. It is possible
that the nervous system of certain animal species is more susceptible
than that of others to this toxin, and this would explain the pre-
dominance of a particular symptom in a particular species of animal.
Kanthack, Durham, and Blandford, and later we ourselves, have
tried to prove the existence of such a toxin.
(i) The fresh serum of infected animals filtered through a
Berkefeld filter; (2) blood or serum kept for several days in order
that all the trypanosomes should be dead ; (3) blood in which the
parasites had been killed by heating to 50° C. ; (4) extracts of the
organs of animals which had died of nagana ; and (5) extracts of
trypanosomes from the blood of the dog or rat separated, as much
as possible, from the red corpuscles by centrifuging, then exposed
to a temperature of 42° C. for sixteen hours or dried over sulphuric
acid, did not, even in enormous doses, produce any toxic symptoms
in animals when inoculated, either under the skin, or, as we have
done, into the brain. Blood very rich in trypanosomes, enclosed in
a collodion sac, and inserted into the peritoneal cavity of a guinea-
pig and of a cat, produced no effect. The whole of the blood of a
very sick rabbit was inoculated into a healthy rabbit without
producing any immediate symptoms of acute intoxication.
[McNeal^ has obtained some evidence of a toxin formation in cultures
of T. hrucei. He found that the first two or three subcutaneous injections
' [The trypanosomes might possibly be present in the small vessels in some
other form — e.g., like the Leishman bodies— which is not very easily recognisable
in sections.]
^ [McNeal, yo«r/z. Infec. Bis., v. i, 1904, p. 538.]
150 TRYPANOSOMES AND. THE TRYPANOSOMIASES
of an attenuated culture into guinea-pigs produced no local effect, but only
a slight general effect. Later injections, however, produced both local
effects (ulceration) and general effects (rapid rise of temperature).]
[Mayeri was unable to prove the presence of a soluble toxin, but found that
precipitins occur in the blood of nagana dogs. T. hrucei treated with trypsin
for three days at 37° C. furnishes on filtration a liquid which, when mixed
with the serum of a nagana dog (o'l to 0-5 extract with 0-5 serum), gives
a turbidity in less than an hour, and later a precipitate. Trypanosomes
not treated with trypsin do not furnish this ' precipitinogen.' The same
' precipitinogen ' hquid remains clear when mixed with the serum of a
caderas dog, thus showing the specificity of the reaction. Mayer thinks
this reaction may be of use in comparing allied trypanosomiases.p
Amongst the factors which may influence the course of the disease
and its severity must be mentioned the race of the animals, and,
probably, heredity in countries in which nagana is prevalent. The
wild animals of Central Africa — buffaloes, antelopes, etc. — although,
susceptible to nagana, can multiply in those districts in which the
tsetse-fly abounds.
Finally, it may be mentioned that animals which are old, badly
nourished, or in a feeble condition, live a shorter time. Horses and
cattle suffering from nagana live for a considerable time if not allowed
to work.
It would be a mistake to attribute the survival of animals, such
as cattle and goats, to the effects of treatment or to the use of an
attenuated virus, without bearing in mind the variable susceptibility
of animals for T. hrucei, and the fact that cattle and goats may
recover spontaneously.
Animals which recover are immune. This fact alone is sufficient
to show the necessity for studying the evolution of nagana in
different species of animals. That study should serve as a basis for
researches having as their aim the treatment or the prevention of
the disease.
Section 4. — Morphology of Trypanosoma hrucei. Effect of
External Agents (Heat, Cold). Cultures. Agglomeration of
the Trypanosomes. Involution Forms.
T. hrucei in the Blood of Infected Animals. — In fresh blood
T. hrucei appears as a small, very motile worm-like body, with an
undulating membrane and flagellum. "When its movements become
sluggish, as happens quickly in ordinary preparations, the wave-like
undulations of the undulating membrane are well seen. The
parasite usually moves with the flagellar end foremost, so that this
must be regarded as the anterior extremity. The posterior extremity
varies in shape : sometimes it is drawn out, sometimes rounded off
or truncated. The movements which are produced by the un-
dulating membrane and the flagellum are not very extensive. The
1 [Mayer, Zeitschr.f. exp. Ther. u. Pathol., v. i, 1905.]
2 [Quoted from Mesnil's abstract of Mayer's paper, Bull. Inst. Past., v. 3,
1905, p. 681.]
NAG AN A 151
parasite does not move about much in the field of the microscope ;
neither does it show the darting, arrow-like movement of T. lewisi.
In the fresh condition neither the nucleus nor the granules,
which are clearly seen after staining, can be distinguished. Never-
theless, neutral red, toluidin blue, and methylene blue stain the
granules in the interior of living trypanosomes ; but when the action
of these substances is continued for a certain time, the parasites are
killed, and the staining becomes general.
All the trypanosomes are approximately of the same length in the
blood of any particular animal. Very small forms are not seen side
by side with the large ones, as in the case of T. lewisi during the
stage of multiplication. The only variation noticeable is that certain
trypanosomes are broader than others, and that they have two
undulating membranes ; these are forms in process of division, with
which we are not concerned at the present moment.
According to Bruce, the trypanosome of nagana assumes different
forms in the blood of different animal species. In the dog the
parasite is relatively short and stumpy, with a blunt posterior
extremity ; in the horse it is almost twice as big, and the posterior
extremity drawn out and pointed.
According to Plimmer and Bradford, the dimensions of the
parasite vary with the period of the disease and the species of
animal : the largest forms are seen in the rat at the moment of
death, the smallest in the rabbit during the early days of the disease.
We have studied T. brucei in different animal species — rat, mouse,
guinea-pig, rabbit, dog, horse, donkey, sheep, and goat — and we have
not seen such marked differences as are recorded by those observers.
When the parasites are examined only in fresh blood, it is easy to
fall into error with regard to their size on account of the variation
in size in the different animal species of the red corpuscles, which
one uses instinctively for the purpose of comparison. Thus, in the
goat the diameter of the red corpuscles is only 4 /i to 4'5 /x, in the
mouse 5'5 /x to 6 //., and in the rabbit 6 /x to 7 ;«,; consequently, if one
examine trypanosomes in the blood of these three animals, the
tendency will be to regard the parasites as larger in the goat and
mouse than in the rabbit. In order to obtain an accurate estimate
of the size of trypanosomes, it is necessary to measure them in blood
preparations well fixed and stained. In that way we have shown
that T. brucei has approximately the same size in the rat, mouse,
guinea-pig, rabbit, and dog — namely, 26 /* to 27 /x long (flagellum
included), by 1*5 jj. to 2*5 /x wide. In the horse and donkey the
parasite is longer, varying from 28 /x to 33 /t, its width being about
the same.i
^ This passage is quoted from our paper in the Ann. Inst. Past., January, 1902.
We have never altered our opinion on this point, as might be supposed from a
sentence in the recent paper of Rabinowitsch and Kempner. In our note of
November 17, 1900, we gave the length as 30 /n to 34 /x, as at that time we had seen
the trypanosome only in the blood of the horse. In our note of March 23, 1901, we
gave 25 fi to 30 ft as the length of the trypanosomes seen in the blood of the rat,
mouse, dog, and rabbit. The figures we have given since are simply more exact.
152 TRYPANOSOMES AND THE TRYPANOSOMIASES
When the blood is centrifuged, the trypanosomes gather together
at the upper part of the layer formed by the red corpuscles.
Kanthack, Durham, and Blandford recommend this procedure when
looking for the parasites in a blood in which they are very scanty.
If the blood contains very many trypanosomes, the parasites form
an obvious whitish layer. In this way the parasites can be obtained
almost pure.
Trypanosoma hrucei IN Stained Preparations (Fig. 4 in coloured
plate). — After staining by the method given in Chapter II., the
structure of T. hrucei can be well made out.
The protoplasm stains a deep blue, and, as a rule, very
large deeply-staining granules are seen in it, especially in the
anterior half of the body (Fig. 22, /). The posterior extremity of
the parasite often has the appearance of a truncated cone. The
nucleus, situated about the middle of the body, is elongated ; in its
interior are numerous granules staining more deeply than the chief
chromatic mass (Fig. 22, a)} Near the posterior extremity is the
centrosome (6), staining more intensely than the nucleus; it is often
surrounded by a small clear space.
The flagellum, free anteriorly {d)^ is continued posteriorly along
the whole length of the undulating membrane (c), of which it shows
up the folds, and extends back to join the centrosome. Although
the flagellum appears to be separated from the centrosome by a
small clear area, there is no doubt that it is continuous with it. In
studying the involution forms later on, we shall see that isolated
ilagella, still attached to the centrosome, are frequently met with
when the protoplasm and the nucleus have disappeared.
[The trypanosomes seen in stained films are not always of the same
type. Prowazek^ differentiates three kinds of parasites in the blood,
which are very similar in appearance to those described in the case of
T. levjisi, and are regarded by him as indifferent, male, and female
■■ [Quite recently Ronald Ross and J. E. S. Moore have stated {Brit. Med.
Jo2irn., January 19, 1907, p. 138), that on staining hquid blood containing T. brucei
and T. equiperdum with nuclear stains, such as basic fuchsin and thionin, the
whole of the nucleus does not become coloured, as it does by the various modifi-
cations of the Romanowsky, method. A much smaller central sphere stains by
basic fuchsin, etc., and it is suggested that this is the true chromatin portion of
the nucleus of the trypanosome. The peripheral part of the nucleus is regarded as
a vesicle bounded by the nuclear membrane, and usually filled up by the red
colouring matter of the Romanowsky reagents. Ross and Moore think that
their observation tends to reopen the cytology of trypanosomes and aUied
organisms.]
^ One sees a certain proportion of trypanosoijnes in which the protoplasm
extends along the flagellum right to the end ; in such cases one cannot, strictly
speaking, talk of a free part of the flagellum. Those forms are undoubtedly
associated with repeated subdivision. Moreover, after the division of a trypano-
some with free flagellum, as a rule one of the two individuals retains the free part
of the original flagellum ; the other has, therefore, at first a flagellum without a free
portion.. The occurrence of such forms is not the rule with T. brucei, although it
is, as we shall see later on, with T. dimorphon (Chapter VII.).
^ [Prowazek, Arb. a. d. kaiserl. Gesund., v. 22, 1905.]
NAG AN A
153
forms. Prowa2;ek also describes the same complexity of structure in
T. brucei as in T. lewisi (see p. 6g).]
Multiplication Forms. — Bruce states that multiplication takes
place by longitudinal division, but he dismisses the subject in a few
words.
Kanthack, Durham, and Blandford did not see any multiplication
forms of the parasite. They record the occurrence in the lymphatic
glands, in the bone-marrow, and in the spleen, of small forms
I /* to 2 /i in diameter, oval in shape, and with or without a
short flagellum, which they look upon as young forms of the
parasite.
According to Plimmer and Bradford, there are two modes of
reproduction for the trypanosome of nagana: (i) direct division (longi-
tudinal or transverse); and (2) reproduction preceded by conjugation,
Fig. 22. — Multiplication of T. brucei.
I. Trypanosome of nagana (a, nucleus; b, centrosome; c, undulating membrane;
d, flagellum). 2. The same trypanosome at the commencement of division (there
are two centrosomes, and the flagellum and nucleusfare undergoing division).
3, 4, 5. More advanced stages of division. (Magnified about 2,000 diameters.)
resulting in the formation of amoeboid and plasmodial masses which
are found in the spleen. These latter forms are said to give rise to
flagellated parasites by a process of segmentation. The second
mode of multiplication is stated to be commoner than the former.
We have seen above that, on examining fresh blood, large forms
are seen which have two undulating membranes, and sometiines two
flagella. The simple observation of fresh blood shows, therefore,
that multiplication by longitudinal division takes place. To study
the different phases of division it is necessary to examine stained
preparations. In animals infected with nagana dividing forms are
always seen in the blood. The study of those forms is, therefore,
easier than in the case of T. lewisi, which has a very limited period
of multiplication, after which only adult parasites are seen in the
blood.
154 TRYPANGSOMES AND THE TRYPANOSOMIASES
Fig. 22 (2, J, ^, and 5) represents different stages in the division
of r. brncei} A trypanosome about to divide increases in size and
enlarges in all dimensions. The centrosome, flagellum, nucleus,
and protoplasm successively divide, the centrosome always dividing
first.
1. Division of the Centrosome and Flagellum."— The centrosome
becomes elongated, then divides into two small rounded bodies,
placed, as a rule, one above the other (Fig. 22, 2) ; at the same time
the adjacent part of the flagellum thickens and divides. Fig. 22
{2, J, and 7) shows different stages in the duplication of the flagellum.
In Fig. 22, 4, the new flagella are separate up to the point where the
flagellum becomes free, but sometimes the ffagellum divides through-
out its whole length.
2. Division of the Nucleus. — The nucleus increases in size,
and becomes elongated ; the chromatin collects at the extremities
(Fig. 22, 2), and finally the two daughter nuclei separate (direct
division). At first close together, the nuclei soon separate from one
another (Fig, 22, j and 7). They are usually oval in shape.
3. Division of the Protoplasm. — The protoplasm divides into two
almost equal parts around the nuclei. In well-stained preparations
this division is very obvious ; a clear space separates the two masses
of protoplasm, which are stained blue.
The two parasites remain close together for some time, and
this explains the large forms with two undulating membranes seen
in fresh blood.
The parasite remains active throughout the whole period of
division, motility being only slightly diminished.
The division of the cytoplasm may begin at the anterior part of
the body, as in Fig. 22, 5, or at the posterior. It sometimes happens
that the two parasites resulting from the division of a trypanosome
themselves subdivide before the division of the cytoplasm is complete,
but such cases are very rare.
We have carefully examined the peritoneal fluid, the lymphatic
glands, and the spleen of animals inoculated intraperitoneally, but
we have never seen either multiplication forms or the small forms
which Kanthack, Durham, and Blandford have described as young
T. brucei. Moreover, we have not met with the amoeboid or
plasmodial forms of Plimmer and Bradford. When studying the
agglutination of the trypanosome of nagana and its involution
forms later on, we shall have occasion to return to this question, and
shall show how Plimmer and Bradford were led to believe in the
existence of conjugation and plasmodial forms.
The method of multiplication of T. brucei is in reality very
simple ; it always occurs by longitudinal division, and after the two
^ Laveran and Mesnil, ' On the Mode of Reproduction of the Trypanosome of
Nagana,' Soc. de Biol., March 23, 1901.
^ [For recent accounts of the details of division of T. brucei see later.]
NAG AN A
155
resulting trypanosomes separate, they are almost of the same size.
The multiplication forms in fresh blood differ from the ordinary
forms only by their greater width, which explains how observers,
who had not at their disposal a method of staining by which they
could study the different stages of fission, came to err regarding the
mode of multiplication of these parasites. One is always inclined to
look for small forms as multiplication forms of a parasite, but in this
case, as a result of the particular mode of subdivision, the young
forms are almost as large as the adult.
Schilling and Martini,^ who have studied the Togoland virus,
have, like ourselves, observed only one mode of division, namely,
longitudinal fission.
[According to Prowazek's recent researches {loc. cit.), the details
of the division of T. brucei, as of T. lewisi, are very complicated. The
Fig. 23. — Details in the Division of Nucleus and Centrosome of T. brucei.
1,2. Division of the centrosome. 3,4. Division of the nucleus. {A!fter Prowazek.)
centrosome becomes thickened and elongated, and subsequently
dumb-bell shaped. The two thicker terminal portions then separate,
but remain connected by a slender thread (see Fig. 23, /, 2). The
nucleus also enlarges ; its chromatin becomes grouped into eight
rod- shaped chromosomes, which divide in a similar fashion to the
centrosome. The nuclear karyosome (karyocentrosome) has usually
divided at this stage. Fig. 23, 4., shows the karyocentrosome drawn
out with the chromatin grouped around its two ends. The chromatic
granules in the protoplasm may also divide, as in Fig. 23, j.]
[As in the case of T. lewisi, Prowazek maintains that the flagellum
does not divide,^ but that the whole of the flagellar apparatus is
derived from the new centrosome. He found that the nucleus,
^ Martini, Zeitschr. f. Hyg., v. 42, 1903, pp. 341-350, and Festschrift zumdo,"'
Gebitrtstage von R. Koch, Jena, 1903, p. 219.
2 [McNeal says the same thing of T. brucei in cultures.]
156 TRYPANOSOMES AND THE TRYPANOSOMIASES
centrosome, flagellum, periplast or ectoplasm, and the special
' myoneme,' or fibrillary layer surrounding the body, withstand the
digestion of phagocytosis the longest. From this observation he
concludes that all these structures are of nuclear nature and origin.]
[Although the sexual phases of this trypanosome would normally
only occur in the appropriate tsetse-fly, Prowazek occasionally,
though rarely, observed the maturation process of female parasites
in the blood. This, he states, consists of two divisions of both
nucleus and centrosome, only one of the four elements of each kind
persisting. In one case, in the blood of a guinea-pig just dead,
Prowazek saw the process of conjugation completed on the slide, and
he found several stages in a stained specimen of the blood. ^]
[The Morphology of the Trypanosomes in the Tsetse-Fly.
— Koch^ has described two well-marked forms of the parasite in the
digestive-tube of infected tsetse-flies {Glossina morsitans and Gl.fusca).
(i) Large forms, with abundant cytoplasm staining dark blue, and with
a large, round, reticulated nucleus; and (2) thin, elongated forms, with
feebly-staining protoplasm, and a long rod-shaped nucleus composed
of a homogeneous mass of chromatin. These Koch regards as female
and male forms respectively. Koch states, moreover, that the sexual
forms of T. brucei in Gl. morsitans and Gl.fusca are distinct from
those of T. gambiense in Gl. palpalis, and that these differences in the
evolution forms will serve to differentiate the pathogenic mammalian
trypanosomes.]
[Novy,^ from his observations on the flagellates of mosquitoes
and of tsetse-flies, thinks that the forms described by Koch as
resulting from the development of T. brucei and T. gambiense in
Glossina, have really nothing to do with these flagellates. As
Minchin had previously shown, they are probably ' wild ' or native
trypanosomes of the tsetse-flies.]
Differential Diagnosis of T. bnicei from Allied Trypanosomes. —
In Chapter IV. we drew attention to the differences between
T. brucei and T. lewisi. The reader is referred to subsequent
chapters for the differences between T. brucei and the other patho-
genic mammalian trypanosomes.
The Preservation of T. brucei in the Blood in vitro. —
According to Bruce, the blood of animals infected with nagana is
still infective four days after it has been collected in vitro, provided
it is not allowed to dry. Dried blood was sometimes still infective
at the end of twenty-four hours, but that was exceptional. •
Kanthack, Durham, and Blandford found that T. brucei may
remain alive in vitro from one to three days, exceptionally from four
to six days.
In preparations of blood ringed with vaseline Plimmer and
1 [From Mesnil's abstract in Bull. Inst. Past., v. 3, 1905, pp. 553, 554.]
2 [Koch, Sitzungsber. d. K.pr. Akad. d. Wiss., v. 46, 1905, p. 958.]
^ [Novy, _/3«r«. Infec. Dis., v. 3, 1906, pp. 394-411.]
NAG AN A 157
Bradford sometimes found living trypanosomes at the end of five to
six days. Blood collected aseptically and preserved in contact with
oxygen remains virulent for at least three days, according to the
same observers.
Blood containing T. brucei collected aseptically, mixed with
citrated salt solution, and kept at the temperature of the laboratory,
may be still virulent at the end of three days. Such a rpsult is not
constant, however, and blood kept for only forty-eight hours may
sometimes be found to have lost its virulence.
We have already seen that in animals inoculated with trypano-
somes preserved in vitro the appearance of the parasites in the
blood is considerably delayed. It is very important to remember
this fact in these experiments, otherwise one may record as negative
inoculations the results of which are really only delayed.
Trypanosomes keep well and remain active for a longer time in
blood mixed with serum than in pure blood. We have seen trypano-
somes still active at the end of three days in defibrinated rat's blood
mixed with an equal quantity of horse serum, whereas in pure blood,
even at the end of twenty-four hours, no living trypanosomes could
be seen. Human serum and that of animals resistant to nagana
(birds) are just as useful for the preservation of trypanosomes as
the serums of the most susceptible animals (see later ' Cultures ').
[Jakimoffi has recently made some similar observations. Defibrinated
trypanosome-containing blood after being kept for two days at 0° to 5° C,
or for six days at 20° C, was still infective for mice. The addition of horse
serum to the blood had no effect, the mixture being infective for mice after
keeping for six days at 20° C. The addition of 6 per cent. NaCl, on the
other hand, was distinctly harmful. He found that blood diluted even
50,000 times can still infect ; the incubation period is prolonged to fifteen
days, and death occurs three days later. Different germicides killed the
trypanosomes very rapidly : potassium permanganate, i per cent., in one
minute; HgClj, o'l per cent., in two to three minutes; carbolic acid,
5 per cent., in four to five minutes.]
The Action of Cold. — We have already drawn attention to the
long time that T. lewisi can be kept alive in the ice-chest. T. brucei
does not possess the same property, for it does not keep better in
the ice-chest (5° to 7° C. above zero) than at the temperature of the
laboratory.
Blood kept for three to five days in the refrigerator has on
several occasions given us negative results on inoculation. Such
negative results may even be obtained when on microscopical
examination some slightly active trypanosomes are still found.
In blood which is kept in the ice-chest the trypanosomes rapidly
alter their shape. Later on we shall describe these changes of form,
which are produced in other ways, as well as by prolonged exposure
to cold (see ' The Involution Forms '). Cold diminishes the activity
1 [Jakimoff, Centralb. f. Bakter, I, Ref., v. 38, 1906, pp. 13-16.]
158 TRYPANOSOMES AND THE TRYPANOSOMIASES
of the trypanosomes, but on taking them out of the ice-chest their
activity becomes more marked.
Ahhough the trypanosomes of nagana cannot resist the prolonged
action of moderate cold, they show great resistance to sudden falls of
temperature to —50° C, —55° C, and even —191° C, as the
following experiments will show.
In all these experiments we used rats' blood containing many T. bnicei,
diluted with citrated salt solution.
Experiment i. — Blood exposed for half an hour to a temperature of
-15° to -i8°C.
Experiment 2. — Blood exposed for twenty minutes to - 15°, and after-
wards for eight minutes to - 25° to - 30° C.
Experiment 3. — Blood exposed for half an hour to — 15°, and afterwards
for five minutes to — 50° to - 55° C.
Experiment 4. — Same as preceding, except that the blood was warmed
up quickly, and not slowly, as in Experiment 3.
In all these cases at the end of two hours many normal active trypano-
somes were found in the blood, when thawed and warmed up again to
the temperature of the laboratory.
Mice inoculated subcutaneously with these trypanosomes (two mice
for each experiment) died of nagana as quickly as control mice, except in
Experiment 4, in which the control mouse died first.
Experiment 5. — Rat's blood containing many T. hrucei, diluted with
citrated salt solution, was exposed to the temperature of liquid air. At
the end of five minutes the tube was withdrawn and allowed to warm up
again. One-quarter c.c. was used to inoculate mouse i ; the remainder was
again exposed for ten minutes to — 191° C. ; after being warmed up again
it was used to inoculate mice 2 and 3. Finally the blood kept for twenty-
five minutes at — 191° C. was used to inoculate mouse 4. On cursory
examination, the trypanosomes in these experiments appeared motionless.
They were, however, still virulent.
Mouse I became infected in 5 days, and died in 9-| days.
'» 2 " »j )' 5 " >> 02 »>
JJ 3 J» '» 5 " n Qt )>
JJ 4 )' )» - )) jj D ,,
„ control „ „ 2 „ „ 5^ „
Action of Heat. — Two factors must here be considered: (i) the
temperature, and (2) the time during which the blood is exposed to
the raised temperature.
Specimens of blood heated for three hours to 40° C, and for one hour
and twenty minutes to 42° C, were still virulent ; other specimens heated
for forty minutes to between 41° and 44° C, and for twenty minutes to
44-5° C, did not produce an infection in animals on inoculation. Heat-
ing to 44° to 45° C, therefore, very rapidly kills the trypanosomes, whilst
with temperatures of 40° to 43° C. prolonged exposure is necessary.
When one examines the blood which has been exposed for an hour to a
temperature of 41° C, at first sight it appears as though all the trypano-
somes were destroyed ; the parasites are motionless, deformed, and almost
unrecognisable by anyone who has not often seen them in this condition.
The majority are spherical and appear dead, but blood inoculated into a
rat or a mouse still produces an infection, only after a slightly longer
incubation period.
NAG AN A 159
In animals inoculated with blood heated to 40° C. from one hour and
fifty minutes to three hours we have seen trypanosomes appear in the
blood on the fifth or sixth day.
We have already seen that the number of trypanosomes in the
blood of different species of animals infected with nagana varies
considerably. The temperature of the blood seems to play an
important part in this connection. When the temperature goes up
to 40° or 41° C, the trypanosomes diminish gradually in number in
the general circulation. In the case of the pig recorded previously
the rectal temperature was, as a rule, about 40° C, and under these
conditions the parasites were never seen in the blood.
We have not only studied the action of heat and cold upon the
trypanosomes of nagana, but we have submitted these parasites, «»
vitro, to the action of a large number of chemical substances, in order
to find out, from the point of view of treatment, the toxic effect, if
any, of these substances upon the T. hrucei (see Section 6).
[Action of X Rays and other Agents. — Exposure of liquid prepara-
tions of blood containing active trypanosomes to the action of Roentgen
rays, Finsen rays, and radium emanations for half to one hour was found
by Rossi to have no harmful effect upon the parasites. De Nobele and
Goebel had previously shown that X-rays have no action in vitro upon
trypanosomes, and more recently they have found that radio-therapy has
no effect upon the course of experimental nagana in animals (see
Chapter XIII. on ' Treatment ').]
[Goebel 2 has studied the action of cobra venom on T. hrucei. He
finds that at 37° C, i c.c. of a i per cent, solution of venom in physio-
logical saline mixed with o-i c.c. suspension of trypanosomes from guinea-
pigs' blood, causes haemolysis and trypan olysis in fifteen minutes. At
19° C. it takes two hours, and at 0° C. there is no action. The trypano-
somes are rapidly destroyed, and no intermediate involution forms are
seen.]
Cultures. — The brilliant results obtained by Novy and McNeal
in the cultivation of T. lewisi led them to attempt to cultivate patho-
genic trypanosomes.^ They succeeded with T. brucei. The methods
used being the same as for T. lewisi, the reader is referred to the
account given in Chapter II. The authors lay stress upon the fact
that T. brucei grows only exceptionally in the condensation water of
an agar medium containing only a half, or less than half, its volume of
blood. The best results appear to be obtained with mixtures con-
taining 2 to 3 parts of blood to i of agar.* Even on these media
only one or two out of a large number of tubes show any sign of
growth; and, moreover, nearly all the trypanosomes inoculated
succumb, and the cultivation always starts, at the end of about twenty
days, from a very small number of parasites which have survived —
1 [Ross, Brit. Med. Journ., 1906, v. i, p. 798-]
2 [O. Goebel, Ann. Soc. Med. Gand, 1905,3rd fasc. ; abstract by Mesnil in
Bull. Inst. Past., v. 3, 1905, p. 714.]
3 Novy and McNeal, /(Jk;';?. Amer. Med. Assoc, November 21, \<)o^; Joum.
Infect. Dis., v. I, January 2, 1904, pp. 1-30.
* We have seen that T. lewisi grows in media containing i part of blood to 2,
5, or even 10, of agar, but it prefers media containing 2 parts of blood to i of agar.
i6o TRYPANOSOMES AND THE TRYPANOSOMIASES
' survival of the fittest.' In order to give an idea of the difficulty, it
is sufficient to state that only four out of fifty attempts to cultivate
trypanosomes from the blood of animals suffering from nagana
(obtained from Zululand, Bruce) were successful. But once a
culture begins to grow the difficulty ceases, for subcultivations are
easily made.
[In their first paper (loc. cit.) Novy and McNeal state that one of
their cultures had grown through eight generations of subcultures
in 100 days. In a later paper^ they stated that one of the cultures,
started on August 27, 1903, was then in its twenty-seventh generation,
but no mention is made of its virulence] .
Cultures grow at the room temperature, at 25° C. and at 34° C,
but the higher the temperature the sooner does the culture die. At
the room temperature cultures have been found still living after
forty- five days.
Trypanosomes which have been kept at 25° C, and have really multi-
plied, are rarely as virulent as parasites occurring in the blood. As an
exception it may be mentioned that trypanosomes of the third genera-
tion, which had been outside a host for sixty-two days, killed mice in
three to five days, like trypanosomes passed through animals. As a
rule, trypanosomes in cultures kill rats and mice in seven to ten days,
instead of three to five days. Cultures twenty-two days old may
still be virulent.
If cidtures grown at 25° C. are heated to 34° C, they generally lose
their virulence in less than forty-eight hours, although the trypano-
somes may remain alive for several days.
In culture tubes, even without multiplication taking place, the
parasites inoculated sometimes remain alive for ten and even eighteen
days. These inoctdated trypanosomes, before losing their motility,
lose their virulence, generally after five days, but exceptionally only
after ten days. Before losing their virulence they become somewhat
attenuated, as is shown by the prolongation of the incubation period.
These are analogous to the results obtained with preserved trypano-
somes, but the disease, once declared, is always fatal. An inocula-
tion not followed by infection does not confer any immunity.
Attempts at immunization by non-virulent cultures did not give
any appreciable result (merely a delay of one or two days on subse-
quent inoculation of the virus), probably because 'the material
injected in the first inoculation was too feeble ' (Novy and McNeal).
When grown at 25° C, T. brucei shows two large, highly refractile
granules in the anterior half of the body. At 34° C. these granules
increase in number and size, and may attain a diameter of i /x. They
probably stand in some relation to an alteration in vitality of the
parasites, for they are not found in the blood of animals inoculated
with these cultures. This fact, together with all we have said about
the difficulty in obtaining cultures, of the loss of virulence in cultures,
I [Novyiand McNeal, /ijz/r«. Amer. Med. Assoc, May 28, 1904.]
NAG AN A i6i
especially when heated to 34° C, proves, as Novy and McNeal state,
that the ideal medium for the cultivation of T. brucei has yet to be
discovered.
In cultures of T. brucei the parasites are either in pairs, joined
by their posterior extremities, or in colonies of 10 to 20 long, thin
parasites showing wriggling movements, with the flagella apparently
arranged around the periphery. The parasites vary a little in size,
measuring from 15 /* to 17 /^ in length (flagellum, undoubtedly, not
included). T. brucei is longer and proportionately narrower than
T. lewisi ; its flagellum is very short.
' The motion of T. brucei is slow and wriggling, and only excep-
tionally is a slowly progressive form observed. The wave motion
slowly passes along the thick undulating membrane, and gives the
appearance of a spiral rotation to the entire cell ' (Novy and McNeal).
[McNeal 1 and Smedley^ have recently made further observations
upon the cultivation of T. brucei. McNeal recommends a modification ^
of the original blood-agar medium for isolating the trypanosome from an
infected animal. For subcultures he used a blood-agar containing four
times as much meat extractives. Transplantations from the first culture
were made as early as the fourteenth day and as late as the fifty-second
day. He found 25° C. to be the best temperature, though the room
temperature is fairly good.]
[By a special method of treatment,'' McNeal was able to show that the
new flagellum was not produced by a splitting of the original flagellum,
but that it developed from the new centrosome by the side of the old
flagellum.]
[Smedley- succeeded in cultivating T. brucei on rabbit-blood agar
three times out of ten. In young cultures he found the trypanosomes to
possess very active movements, and to move across the field fairly quickly.
The cultural forms were somewhat smaller than the forms seen in the
blood, the average dimensions in stained films being 18 ju. to 23 // long
(including free flagellum, which measured 3 /^ to 5 /x) by 2-5 fx to 3'5 /i
wide. The undulating membrane was well developed, and the centro-
some was nearly always posterior to the nucleus (unlike T. lewisi in
cultures). The colonies of T. brucei were unlike those of T. lewisi, being
much smaller and muchlessnumerous; the flagella are directed peripherally
in them, and secondary massing together of the colonies does not occur to
any extent. The cultural characteristics, therefore, are sufficient by them-
selves to distinguish T. brucei from T. lewisi. |
Agglomeration. — Under certain conditions the trypanosomes
of nagana become arranged in a regular fashion, like those of the
1 [W. J. McNeal, /(7«r«. In/ec. Dis., v. i, 1904, pp. 5I7-543-]
2 [R. D. Smedley, /cz^ra. Hyg., v. 5, 1905, pp. 24-43.]
^ [Add 2 volumes sterile defibrinated rabbit's blood to i volume of the following
medium, previously sterilized in tubes or flasks and cooled to 60° C. : The extractives
of 125 grammes of beef in 1,000 c.c. distilled water ; agar, 20 grarnmes ; peptone,
20 grammes ; common salt, 5 grammes ; normal solution of sodium carbonate,
10 c.c]
^ [Add a drop of defibrinated rat's blood, rich in trypanosomes, to a mixture of
-J c.c. defibrinated rabbit's blood and j c.c. of a molecular solution of noimal
sodium phosphate. Let it stand for half an hour, make films, and stain. '1 he alkaline
phosphate dissolves away the unduladng membrane which sheaths the flagellum,
and this is then set free.]
II
i62 TRYPANOSOMES AND THE TRYPANOSOMIASES
rat. They often join together in pairs.^ Sometimes they form
primary agglomeration rosettes, but the large secondary agglomera-
tions, which are common in blood containing T. lewisi, are rarely
seen with this trypanosome. The trypanosomes are always joined by
their posterior ends, as can be readily made out in stained specimens.
Fig. 24, 12, represents trypanosomes agglomerating in rosette form,
as seen in fresh blood ; Fig. 24, ij, shows two trypanosomes in a
stained specimen joined by their flattened posterior extremities, so
that the line of separation between the parasites is hardly visible.
These trypanosomes united in pairs suggest conjugation, but such
an interpretation is inadmissible. Agglomeration is not seen in pure,
fresh blood, but is produced only under abnormal conditions, and,
moreover, ■ the number of parasites which agglomerate varies very
much.
With T. brucei, as with T. lewisi, one may observe the rosettes
break up after a variable interval.
We have seen agglomerations of trypanosomes form in pure
blood a half to one hour after removal from the heart ; in peritoneal
exudates after intraperitoneal injection into rats or mice of blood
containing many parasites ; and in blood mixed with salt solution
kept for twenty-four hours on ice, or heated for half an hour to 41° C.
On mixing equal parts of horse serum and defibrinated blood
from a rat or mouse rich in trypanosomes, we have obtained very
beautiful persistent agglomeration masses. At the end of some
hours, however, the trypanosomes lose their characteristic shape.
On mixing i part of horse serum with 10 of blood, agglomeration
masses are not produced. Pig serum also agglomerates well.
Sheep serum mixed with an equal volume of the blood of a rat or
mouse rich in T. brucei gave in one case well-marked agglomeration
masses, but in another case the agglomeration was less marked and
not persistent. The serum of a goat gave, with an equal volume of
blood, small and non-persistent rosettes. Human serum was neither
agglutinating nor microbicidal.
The following serums, mixed with an equal volume of the blood of
a rat or mouse containing many T. brucei, did not exhibit any
agglutinating properties : the serum of a rat, either normal or
immunized against T. lewisi, and agglutinating those trypanosomes ;
the serum of a normal fowl, and that of a fowl inoculated on
several occasions with T. brucei ; the serum of a normal goose, and
that of a goose inoculated on several occasions with blood rich in
T. brucei.
On adding a drop of water slightly acidulated with acetic acid to
1 These combinations of two parasites are particularly abundant in the peritoneal
fluid of rats or mice inoculated intraperitoneally.
[McNeal (loc. cii.) also saw numerous pairs of trypanosomes, joined by a consider-
able portion of their posterior ends, in the blood of mice shortly before death. The
contact was so intimate that there was no line of demarcation and the centrosomes
showed such various forms (fusion, dumb-bell shapes, and tetrads) that it would
seem to indicate an actual conjugation, as described by Bradford and Plimmer.]
NAG AN A
163
several drops of blood containing many T. hriicci, the trypanosomes
agglomerate and soon change their shape. On the other hand, a
drop of water made faintly alkaline with soda does not produce
agglomeration.
Dead trypanosomes also tend to agglomerate, but in such cases
agglomeration is very irregular.
Involution Forms. — When the trypanosomes of nagana are
under unfavourable conditions, which, however, are not sufficient to
bring about rapid death of the parasites, they show involution forms,
which it is important to recognise. We have seen these forms
produced under various conditions : rat's blood rich in trypanosomes
mixed with the serum of other animals, and kept for several hours in
hanging-drop preparation or in ordinary fresh films ; blood heated
Fig. 24. — Involution and Agglomeration Forms of T. brucei.
7, 8. Spherical forms of trypanosomes in blood mixed with horse serum ; 8 shows
a trypanosome which was undergoing division when it became spherical.
9. Agglomeration of spherical trypanosomes. 10. Trypanosome undergoing disin-
tegration ; the trypanosome has almost entirely disappeared, and the nucleus is very
pale. II. Free flagellum with centrosome. 6- 11 were drawn under a magnification
of 1,400 diameters. 12. Trypanosomes, agglomerated in the form of a rosette, seen
in fresh blood (1,000 diameters). 13. Two trypanosomes, joined by their posterior
ends, seen in a specimen of stained blood (1,600 diameters).
to 41° or 42° C. for an hour or more; blood injected into the
peritoneal ca-O'ity or into the connective tissue of birds, and e.xamined
at the end of one to three hours ; blood kept in the ice-chest or
frozen ; blood of rats treated with arsenic, etc. Fig. 24, 6 to //,
shows different involution forms of T. brucei.
The trypanosome becomes short and stumpy (Fig. 24, 6), then
spherical (Fig. 24, 7). On staining, spherical forms of the parasite
are seen, containing a nucleus, centrosome, and flagellum. Fig. 24, 8,
represents a trypanosome which was undergoing division when it
became spherical ; two nuclei, two centrosomes, and two flagella can
be seen in it.
II — 2
i64 TRYPANOSOMES AND THE TRYPANOSOMIASES
The spherical forms may produce small agglomeration masses
(Fig. 24, p). It is very probable 'that it was these masses which
Plimmer and Bradford saw and described as plasmodia giving rise
to flagellated parasites.
[Rodet and Valleti regard these abnormal parasites not as true involu-
tion forms, which arise gradually as the result of unfavourable conditions,
but as parasites which have undergone a sudden and active change in shape
in response to an abnormal stimulation. By pricking an infected animal
through a drop of i per cent, osmic acid, they found that the trypano-
somes so obtained were all of this ' amoeboid ' type. Rodet and Vallet
suggest that possibly the chemical agents used to fix tissues may account
for the amoeboid forms seen in sections of organs.]
Trypanosomes which are spherical and no longer show any
signs of movement are not always dead, however, for on injecting
blood containing this form of the parasite into a rat or mouse, the
trypanosomes sometimes appear in the blood after a lengthened
incubation period, varying in length with the degree of alteration in
the parasites injected.
If the trypanosomes remain exposed to harmful conditions, they
die and undergo profound alterations, which are seen most clearly
in stained preparations.
The protoplasm disappears first, and can no longer be stained ;
the outline of the parasite becomes considerably narrowed (Fig. 24, 10),
and the nucleus stains badly. Later on the protoplasm and nucleus
have disappeared altogether, and the flagellum is seen either alone or
with the centrosome forming a small swelling at one end (Fig. 24, //).
Section 5. — ^tiolog-y of Nag-ana. The Role of the Tsetse-
Fly and of the Big Game.
Bruce's experiments have placed beyond all doubt the role of the
tsetse-fly in the spread of nagana.^ It is true the part played by
this fly had long been suspected, and Livingstone in particular
had clearly recognised and well described the effects of the bite of
the tsetse upon domestic animals; but for a long time we were
mistaken in our idea of the exact manner in which the bite of this
fly produced its harmful effects. It was thought that the fly itself
was poisonous, and several observers looked, but in vain, for poison
glands in the insect. It was Bruce who showed that the tsetse-fly
is not poisonous, and that if its bite is, as a rule, so dangerous, it is
because the fly sucks alternately the blood of animals suffering from
nagana and of healthy animals, and that it inoculates into the latter
the pathogenic trypanosomes.
It is, nevertheless, right to state that other observers had suspected
the truth. ' The poison germ,' wrote Livingstone in 1857, • • • •
'seems capable, although very minute in quantity, of reproducing
1 [Rodet and Vallet, Arch. mM. exp^r., v. 18, July, igo6.]
- For the biology, morphology, and classification of the tsetse-flies, see
Chapter XVIII.
NAG AN A 165
itself . . . .' In 1875 M^gnin .stated that the tsetse-fly carries a
virus, and does not inoculate a poison of its own. In 1879, the day
after the discovery of the role of the mosquito in filariasis,
J. J. Drysdale suggested that the fly 'might be an intermediate host
of some . . . blood parasite, or the means of conveying some infectious
poison.' In 1883 Schoch expressed himself almost in the same
terms. In 1884 Railliet and Nocard, who also suspected this,
found that inoculations with the proboscis of the tsetse v/ere
harmless.
We come next to Bruce's experiments, which prove conclusively
that a tsetse-fly which has bitten an infected animal, and after-
wards bites a healthy animal, can convey the disease to the
latter. Bruce used dogs in his experiments. First he showed that
flies fed on infected animals, then kept in captivity for several days,
and afterwards placed on two dogs, did not infect. The tsetse,
therefore, cannot give rise per se to a local or general disease in
susceptible animals. Secondly, flies fed on a sick dog and
immediately afterwards on a healthy dog conveyed the disease to
the latter. The flies were infective for twelve, twenty-four, and
even forty-eight hours after having fed on an infected animal ; but
under these conditions infection was not easily produced, many and
repeated bites being necessary.
That point being proved, Bruce tried to find out whether the fly
acted as a simple carrier or as a true intermediate host. He found
that the blood of an infected animal after drying on threads was still
infective, though rarely, after twenty-four hours — never after forty-
eight hours. On the other hand, blood kept moist in an aseptic
condition was still infective at the end of four days, but not after
seven days. As the proboscis of the fly to a certain extent prevents
the blood from drying up, it follows, if the fly acts as a simple
carrier, that the figures found by Bruce for the time that the virus
remains active in the fly should be intermediate between those
obtained with dried and with liquid blood.
It is, therefore, by means of the fly that animals living in
infected areas contract nagana. Horses were taken for several
hours during the day into such districts ; they were not allowed to
eat or drink during that time ; they were bitten by the tsetse-flies
and contracted the disease. Drinking-water and food, which had
often been suspected, could not have played any part in the
causation of the disease in this experiment, so that it must have
been the flies which communicated the disease.
A final experiment proves that this is the case. Flies were
collected every day in a district where nagana was prevalent, and
were placed upon a healthy animal living in a district where the tsetse
was not found. Care was taken to collect these flies from healthy
animals, yet they gave the disease to animals (a horse and a dog)
upon which they were allowed to feed.
i66 TRYPANOSOMES AND THE TRYPANOSOMIASES
We may, therefore, conclude, with Bruce, ' that it is proved that
the tsetse-fly does commonly, in a state of nature, convey the disease
from animal to animal, and that, on the other hand, there is no
proof that the drinking-water or the eating of soiled herbage plays
any role in the process.'
Can all the species of the genus Glossina play such a part ?
Bruce speaks only of Gl. morsitans, but Austen states that he has
confused two species, the true Gl. morsitans and a closely allied
species, Gl. pallidipes (the photographs in Plate II. in Bruce's paper
represent the latter species).
The question is far from being settled. By analogy with what
is found in malaria and Texas fever, certain authors, such as Stuhl-
mann and Schmidt, think that Gl. morsitans is the only species
which is able to convey nagana. One might immediately raise the
objection that the trypanosomiasis of camels in Somaliland is most
probably spread by Gl. longipennis ; but as the identity of this disease
with nagana is doubtful, the objection has no weight in the present
state of our knowledge.
There is, however, in this connection another point of consider-
able importance. It is hardly questionable that the species of
Glossina have a special action upon the African trypanosomes
which other flies do not possess. We cannot do better than repro-
duce the following passage from Bruce's paper :
' That all blood-sucking flies are not capable of transferring the
fly disease from affected to healthy animals is, I think, shown by the
fact that up here at Ubombo, where we have several species of these
pests, no single instance of the disease arising spontaneously has
occurred, although healthy horses, cattle, and dogs, have been con-
stantly and closely associated with those suffering from the disease.
Why this should be so is at present a mystery, and it is to be hoped
that some point may be discovered which will throw light on the
subject. There may be some anatomical peculiarity in the tsetse
which enables it to act as carrier, or there may be some undiscovered
fact in the life-history of the parasite associating it with this particular
species of fly.'
These questions remain unanswered at present. Considerations
based upon the comparative geographical distribution of the tsetse-
fly and of the trypanosomiases of the type of nagana do not allow
any definite conclusion to be drawn. However, if we note, on the
one hand, the very close agreement existing between the distribution
of nagana and of Gl. morsitans (we have already disposed of the
objection in the case of the trypanosomiasis of dromedaries in
Somaliland),^ and, on the other hand, the fact that nagana does not
1 'At the present moment.' says Austen, 'there is no definite information of the
presence of nagana in a locality where Gl. morsitans does not occur. The unex-
pected discovery of Gl. morsitans in Togo, where the existence of a trypano-
somiasis resembling nagana has been recognised, is an important fact in this
NAGANA 167
appear to occur in regions infested by other tsetses, we have evidence,
not absolutely amounting to proof, but very strongly in favour of the
hypothesis that Gl. morsitans (and undoubtedly also Gl. pallidipcs,
which appears to have the same geographical distribution) is the
carrier of nagana, to the exclusion of the other species of Glossina.
The study of the other trypanosomiases has lately received such
an impetus that facts in connection with them accumulate rapidly,
and no doubt very soon all these questions will be answered.
[From the evolution which the malarial parasite is known to undergo
in the body of the mosquito, it seemed probable that trypanosomes would
be found to undergo an analogous development in the body of some blood-
sucking insect or insects. Schaudinn, Prowazek, Koch, and others would
seem to have shown that this is the case with certain trypanosomes.
Schaudinn has described the sexual development of T. nocttia: of the owl
in the body of mosquitoes ; Prowazek that of T. lewisi in the rat-louse ;
and Koch that of T. brucei in the tsetse-fly. We have seen, however, that
Novy, Ross, Minchin, aad others, have found flagellates in mosquitoes
and tsetse-flies which had not been fed experimentally on infected animals,
so that the conclusions drawn by Schaudinn and Koch as to the evolution
of T. noctua and T. brucei in Citlex and Glossina respectively may prove to
be incorrect.]
[Koch^ found that the trypanosome of tsetse disease in German East
Africa is carried by Gl. morsitans, Gl. pallidipes, and especially GZ./;(sc(7. The
other species of Glossina — Gl. tachinoides, Gl. palpalis, and probably also
Gl. longipennis — found there are not concerned in the transmission of tlie
disease. By pressing on the bulb at the root of the proboscis, a small
drop of liquid can be expressed, and in this trypanosomes are found (fifty-
eight times in fuse a, once each in morsitans Sind pallidipes), evidently ready
to be inoculated. These trypanosomes are in various stages of develop-
ment, and no red blood-corpuscles are mixed with them. Koch concludes
from this that there is an undoubted development in the fly. In the
intestines the trypanosomes are rare or absent, nor are they found in other
organs. In the stomach of the fly the trypanosomes multiply and increase
very much in size. There is, then, a well-marked difference between the
large and the thin, elongated forms (described on p. 156), which Koch
regards as female and male respectively. In the posterior part of the
stomach very large forms are seen, with only one centrosome and one
flagellar apparatus, but usually four — sometimes two or eight — nuclei.
These large forms may possibly be fertilized females. Koch did not
follow out the subdivision of these forms, but he supposes that the
elements with nucleus and without centrosome are derived from them.
Eventually Herpetomonas-iorms, with the centrosome in front of the
nucleus, arise.]
[In the liquid expressed from the proboscis all stages in the develop-
ment of the trypanosomes are seen, and some are like the ordinary forms
found in the blood. It is these which determine the infection of a fresh
mammal, and Koch was unable to infect rats with the trypanosomes from
the flies' stomachs. Flies fed on recently infected cattle did not become
infected, but they did when fed on oxen and mules with a chronic infection,
connection. Several localities are known in which the G/. morsitajis occurs with-
out nagana being present. This is quite comparable with the fact that Anopheles
may occur in districts where malaria is absent.'
^ [Koch, Deutsche mediz. Wochenschr., November 23, 1905, pp. 1865-1S69 ;
abstracted in Brit. Med. Journ., January 6, 1906, pp. 31, 32, and in Bull. Inst. Past..
V. 4, 1906, p. 34, 35, by Mesnil.]
i68 TRYPANOSOMES AND THE TRYPANOSOMIASES
and with only a few trypanosomes in their blood. Koch suggests that prob-
ably the blood trypanosomes must be in a certain phase of development,
which is found in slightly susceptible animals, such as the buffalo and
antelope, in order to be carried over. (Novy's criticism of Koch's con-
clusions will be considered in the section dealing with the trypanosomes
of tsetse-flies, Chapter XVIII.)]
The proof that the trypanosome of nagana is conveyed by the
tsetse-fly is not sufficient by itself to solve the problem of the aetiology
of the disease. For example, the disease may be contracted in a
district where not a single sick domestic animal exists. Whence
does the fly obtain the virus which it inoculates ? Bruce again has
answered this question for us.
When he arrived in Zululand the Europeans were of opinion
that it was the fly which caused the disease, and we have seen that
they were not wrong. The natives, on the other hand, thought that
the disease was caused by the presence of big game, the wild animals
contaminating the herbage or water by their saliva or their excretions.
A priori, the two hypotheses are not mutually exclusive, and the fact
that the association of the tsetse and wild game is confirmed by all
explorers tends to reconcile them.
Bruce was successful in combining the two hypotheses by proving
that the blood of the wild animals in Zululand may contain the
trypanosome of nagana. It is true the parasite is always very
scanty, for Bruce says in his report that he never saw it on micro-
scopical examination/ but this blood in doses of 5 to 10 c.c. was
infective for dogs. Thus, the blood of one out of eight buffaloes,
of three out of thirteen wildebeest (Catoblepas gnu), and of three out
of four koodoo {Strepsiceros capensis) examined, was found infective
on injecting into dogs. Finally, the blood of a bush-buck {Tragdaphns
scriptus sylvaticus) and of a hyena was found similarly infective.
These animals, therefore, constitute a reservoir of the virus from
which the fly may obtain its supply. As we have already stated in
a previous paragraph, the infection appears to be chronic in these
animals and hardly to affect their health. Nevertheless, it makes
them a source of great danger to these susceptible domestic animals
which are introduced into their neighbourhood.
Is the spread of nagana by means of the fly the only way in
which this disease may be propagated ?'- That appears to be cer-
tainly the case with herbivorous animals. Carnivorous animals,
such as the dog, may often contract the disease through eating
animals which have recently died of nagana, and whose blood
^ Later, however, he found them in the blood, according to a verbal communica-
tion made to Theiler, and published by the latter author.
2 [Markl {Centralb. f. Bakter., I, Orig., v. 37, p. 530) states that in guinea-pigs
the trypanosomes do not seem able to pass through the placenta. This is in
agreement with the observations of Chaussat, Laveran and Mesnil, and others, on
the rat trypanosome, but we have seen that Pricolo observed the passage of
trypanosomes {T. duttoni?) through the placenta of infected mice and their
development in the fcetus (see p. 102) ]
NAG AN A 169
swarms with virulent trypanosomes. Bruce quotes instances of
dogs having contracted the disease in this way. It is well known
that in infected districts the disease in dogs especially affects the
sporting dogs which are introduced into those parts. We have
quoted the case of two cats which became similarly infected ; [also
the two cases in cats recorded by Lacomme. In Uganda, Nabarro
and Greig had a jackal which developed a fatal infection after
devouring a monkey with many trypanosomes in its blood.
Lignieres'^ has recorded instances in which the infection has been
conveyed by the bite of infected animals (capybara) to dogs. He
concludes from this that the saliva itself may contain trypano-
somes and be infective, but it is more likely that the trypanosomes
present were due to an admixture of blood from the gums.^]
It is quite easy to understand that this method of propagation
is much less important than the first method. In a country which
is immune it is impossible for the disease to become endemic or
even epidemic in this way. From the point of view of prophylaxis,
we need concern ourselves only with the former mode of propa-
gation.
Section 6. — Treatment.
I. Treatment by Means of Chemical Substances.
Sodium Arsenite. — Stimulated by Lingard's experiments upon
the arsenical treatment of surra, Bruce in Zululand treated several
horses and donkeys by adding to their food each day a dose varying
from 6 to 12 grains (o"384 to 0768 gramme) of arsenic in the form of
sodium arsenite.' In the most favourable cases the parasites dis-
appear from the blood (on microscopical examination) a few days after
the commencement of the treatment,* and rarely reappear. There is
no ansemia; the animals often remain strong and healthy, and can
do work, which is quite impossible in the case of infected horses
which are untreated. Treated animals survive an appreciably longer
time than control animals, but the treatment has always to be dis-
continued, as the animals can no longer tolerate it, and the trypano-
^ [Ligni^res, Bui/, ct Mem. Soc. cenlr. veter., v. 83, June 30, 1906, pp. 363-
366 ; also Report presented to Section of Pathology, Eighth International Congress
of Veterinary Medicine, Budapest, September, 1905. Abstracts by Mesnil mBuU.
Inst. Past.., vols. 3 and 4, 1905 and igo6.]
^ [Ligniferes also records the case of a rabbit, vaccinated against dourine, which
became infected with nagana by licking the sore places and eating the crusts of a
rabbit with nagana kept in the same cage. He thinks this seems to prove that
T. bfucei can pass through intact mucous membranes, but Mesnil does not agree
with him.]
3 This arsenical treatment of nagana was in vogue long before we were
acquainted with the cause of the disease. See, in this connection, James Braid,
G. W. Balfour, Livingstone (Brit. Med. Joiirn,, 185S, pp. 135, 214, 360).
* Bruce quotes an experiment in which 5 c.c. of the blood of a horse under
treatment did not infect a dog.
I70 TRYPANOSOMES AND THE TRYPANOSOMIASES
somes then reappear in the blood. Only one donkey appears to have
been cured, and he did not acquire immunity.^
Horses and a donkey which were saturated with arsenic rapidly
contracted nagana when taken into a fly area. In a dog prophy-
lactic treatment with arsenic was equally ineffectual. Bruce con-
cludes from his investigations that arsenic is quite useless in the
prevention of nagana, but that it is of use in prolonging the life of
animals after the disease has once started.
The indication was obviously to study, in laboratory animals,
the effect of arsenic compounds which had given, in the hands of
Lingard and Bruce, more or less favourable results in the treatment
of surra or nagana. We have studied the arsenic treatment, particu-
larly in the rat, mouse, and dog. For the treatment of rats we use
the following solution :
Arsenious acid ... ... ... i gramme
Sodium carbonate ... ... ... i gramme
Distilled water ... ... ... 500 c.c.
Boil.
Syringes holding i c.c. are graduated as a rule in twenty divisions,
which gives o'l milligramme of arsenious acid for each division of
the syringe.
For the treatment of mice it is advisable to dilute this solution to
half the strength ; on the other hand, in the treatment of dogs
a stronger solution may be used.
At first in the dog we used intravenous injections of the arsenic
solution, but we found that subcutaneous injections gave quite
as good results as intravenous, and since that time we have used
exclusively the hypodermic method, which is not only more con-
venient, but is the only one applicable to very small animals.
The subcutaneous injections of arsenic in the abdominal region
of rats and mice often give rise to abscesses. This may be avoided,
however, by injecting the fluid into the muscles of the shoulder.
The hair is cut and the skin washed with perchloride of mercury.
The injection is a little painful, and produces in rats and mice an
obvious malaise, which sometimes lasts several hours.
The action of arsenious acid upon the trypanosomes of nagana
is very remarkable, if the drug is used in sufficient doses. In the
rat and mouse we have found that it is necessary to use O'l milli-
gramme of arsenious acid per 20 grammes of animal.
Should a rat of 100 grammes be infected with nagana and have
numerous trypanosomes in its blood, 5 milligrammes of arsenious
acid are injected into the muscles of the shoulder. One to two hours
1 [Moore {Lancet, 1904, part 2, p. 15) states that in the treatment of tsetse-fly
disease in cattle (? nagana) in Nigeria, sodium arseniate (i ounce of a t per cent,
solution, made alkaline with sodium carbonate) given hypodermically once a week
had very good and lasting effects, even in apparently hopeless cases. He does not
state, however, whether the animals w^'ce. permanently cured.]
NAGANA 171
after the injection the blood examination shows no change, but at
the end of five to six hours there is an obvious diminution in the
number of parasites, and at the end of twenty-four hours they can
no longer be found in the blood, or, if present, they are extremely
scanty.
When trypanosomes are swarming in the blood at the time the
treatment is commenced their disappearance is less rapid. It may
not take place in less than thirty-six or forty-eight hours, and some-
times even a second injection is necessary. Unfortunately, this
disappearance of the parasites from the blood is only temporary, and
at the end of forty-eight hours, or at the most of three to four days,
the parasites reappear, at first in small numbers, and rapidly multiply
if a second injection is not given. By repeating the injections of
arsenic at intervals of two to three days, the life of the animal may
be considerably prolonged, but a permanent cure never results. There
comes a time when the arsenical treatment can no longer be
tolerated : diarrhoea, wasting, neuritis, and oedema at the seat of
inoculation are produced. The animal dies of nagana if the treat-
ment is stopped, or of arsenical poisoning if the treatment is
persisted in.
Whereas rats infected with nagana and untreated die on an
average in five days, those treated with arsenic may live for two or
two and a half months. The longest time that we have kept them
alive has been seventy-eight and seventy-nine days.^ ^
In mice arsenic produces the same results as in rats, only it is
more difficult to use in their case, because the drug has to be pushed
more in mice than in rats before improvement occurs. In mice
weighing 14 to 20 grammes o'l milligramme of arsenious acid may
be injected.
Arsenic has given us less satisfactory results with dogs than with
rats. The treatment obviously prolongs the life of the animal,
but much less so than with rats. We have injected into dogs
from 2'5 to 3"5 milligrammes of arsenious acid per kilogramme of
animal.
The earliest injections of arsenic cause the trypanosomes to
disappear more or less completely from the blood, but they soon
reappear, and the animals die in spite of repeated injections. It
seems that arsenious acid loses its effect more rapidly in the dog
than in the rat. In nine dogs infected with nagana' and treated
with arsenious acid, the average duration of the disease was twenty-
five and a half days, the maximum being forty-six days. In dogs
which were untreated the duration of the disease was from six to
sixteen daj's (average ten and a half).
The Mode of Action of Arsenious Acid upon the Trypanosomes of
Nagana. — When blood rich in trypanosomes is diluted with solution of
1 For the details of these experiments, see Ann. Inst. Past., v. l6, p. 792.
^ By a virus which was not obtained from a ruminant.
172 TRYPANOSOMES AND THE TRYPANOSOMIASES ■
citrate and mixed in vitro with the arsenical solution, the trypano-
somes are rapidly killed. If, for example, to 15 drops of blood one
adds I drop of a 2 per 1,000 solution of arsenic, the trypano-
somes are seen to become motionless at the end of fifteen to twenty
minutes, sometimes even more rapidly, whilst in control prepara-
tions (blood without the addition of arsenical solution) mobility
persists.
Arsenious acid is therefore toxic for the trypanosome of nagana
j» vitro, but from that we cannot conclude that it has the same
action in vivo. Some substances which are highly toxic for the
trypanosome in vitro — formalin, for example — have no effect upon it
in vivo.
In order to study the action of arsenious acid upon the trypano-
some of nagana in vivo, we have examined the blood of infected rats
at varying intervals after the injection of solutions of arsenic. The
blood was examined fresh and after staining in the ordinary way.
As a rule, involution forms are found among the trypanosomes two
hours after the injection ; at the end of four to five hours an obvious
diminution in the number of parasites has occurred, and at the end
of twenty-four hours they have entirely disappeared.
The involution forms in rats treated with arsenic are the same as
those which are seen when blood containing trypanosomes is exposed
to a temperature of 41° to 42° C. for some time. The movements of
the trypanosomes become less marked, the parasites are deformed
and granular, and finally assume the characteristic spherical form.
Later on the protoplasm and nucleus disappear, so that in stained
preparations isolated flagella, sometimes with an adherent centro-
some, are seen.
In certain cases there is slight leucocytosis. We have looked
in vain for signs of phagocytosis of living trypanosomes, but
have often seen leucocytes which had engulfed the remains of
trypanosomes, sometimes the nucleus and centrosome being quite
distinguishable.
We think it may be concluded that arsenious acid is micro-
bicidal for the trypanosome of nagana, and that the leucocytes take
up only dead trypanosomes, or those in an advanced stage of in-
volution.
We have endeavoured to ascertain whether the susceptibility
of trypanosomes to arsenic in vitro is diminished in rats previously
treated with this drug for some time. On mixing the arsenical
solution in the same doses (i) with the blood of an infected rat
which had been treated for a long time with arsenic, and (2) with
the blood of an infected rat which was untreated, no appreciable
difference could be observed ; the trypanosomes were destroyed very
rapidly in both cases.
How is it that arsenious acid, although it has an obvious micro-
bicidal effect upon the trypanosomes of nagana, never cures infected
animals? The trypanosomes which are present in the general
NAG AN A 173
circulation are destroyed, but those in certain out-of-the-way parts
of the body^ evidently escape the action of the drug. When the
bulk of the arsenious acid has been eliminated or fixed by the
tissues, these trypanosomes come out again into the blood, and there
multiply rapidly. One might suppose that the spleen was a place
of refuge for the trypanosomes of nagana, as it is for the malarial
parasite. Experiments have shown, however, that arsenical treat-
ment gives no better results in splenectomized animals than in
normal animals.
Trypanred (Trypanrot).^ — We shall see (Chapter IX.) that
Ehrlich and Shiga have introduced a red dye of the benzo-purpurin
series, which they call ' trypanrot,' for the treatment of mice infected
with caderas. According to these authors, this substance is of less
value in the case of mice infected with nagana. The disappearance
of the trypanosomes is never permanent, but a relapse always
occurs.
We have been able to verify this action of trypanred, used in
doses recommended by Ehrlich and Shiga, upon mice and a rat
having numerous T. brncei in their blood. If treatment be not too
long delayed, the trypanosomes disappear from the blood in twenty-
four to forty-eight hours ; the diminution in number and the appear-
ance of involution forms beginning to take place at the end of
twenty-four hours. The action of this substance is, therefore, slower
than that of arsenic or of human serum {vide infra).
In vitro trypanred is only feebly microbicidal. At the end of
three hours' exposure to trypanred (i part of a i per cent, solution
mixed with an equal volume of citrated blood), the trypanosomes
are exactly the same as in a control preparation. One can therefore
understand why it is that involution forms appear very slowly in the
blood of animals treated with this substance. In the leucocytes the
chromatic remains of the parasites acted upon by the trypanred are
seen.^
We have obtained unsatisfactory results in attempts to treat rats,
mice, or dogs, by subcutaneous injections of the following sub-
stances : cacodylate of sodium, arrhenal (dimethylarseniate of
sodium), liquor iodi, iodide of potassium, salts of quinine, toluidin
blue, and methylene blue, all of which have a slight action in vitro
upon trypanosomes ; and of perchloride of mercury, the double
iodide of mercury and arsenic, salts of silver (lactate, fluoride or
^ [Possibly the trypanosomes take refuge in the bone-marrow, or they may
assume a more resistant form, which is different from the typical form, and not
easily recognisable.]
^ [For Mesnil and Nicolle's experiments with other dyes, and for the recent
attempts at treatment, see special article on ' Treatment,' Chapter XI H.]
' A mouse weighing 19 grammes had, on April 7, 1904, numerous trypanosomes
in its blood, and received ^ c.c. of a i per cent, solution of trypanred. On the 9th
the trypanosomes had disappeared, but had become very numerous again on the
1 5th. A fresh injection of | c.c. was given, and the parasites again disappeared.
On April 24 trypanosomes were again numerous, and -J c.c. fluid was injected.
The next morning the mouse died, with very few parasites in its blood.
174 TRYPANOSOMES AND THE TRYPANOSOMIASES
tachiol, and caseinate or argonine), and formalin, all of which have
a considerable effect upon trypanosomes in viiro.
Amongst the drugs which we have tried without success in
nagana may be added : carbolic acid, salicylic acid, chinosol, essence
of garlic, solution of calcium chloride, chloral, and, more recently,
colloidal silver (collargol) .^ The glycerinated bile of dogs which
have died of nagana is also useless for treatment.
2. Attempts at Serum-therapy.
Our researches in this direction include the action of normal
serums and of the serum of animals immunized against nagana.
Amongst the normal serums, human serum is the only one which
has any microbicidal effect upon T. brucei.^
Human Serum. — Human serum, injected in sufficient doses into
infected animals, has a marked effect upon the course of the disease.^
The trypanosomes disappear from the blood, at least for a time,
the progress of the disease is delayed, and sometimes even complete
cure may result.
The serum of adults is much more active than that of the
newly-born.''
Human serum retains its power for some time when it has been
collected aseptically, but serum in which moulds or bacteria have
developed loses its activity rapidly.
Dried human serum retains the properties of the liquid serum for
at least six months; O'l gramme of dried serum corresponds to
about I c.c. of liquid serum, and when used should be dissolved in
I c.c. of distilled water.
Pleural fluid is less active than blood-serum, and ascitic fluid is
still less active than pleural fluid.
Our experiments upon the treatment of nagana with human
serum have been carried out almost exclusively upon rats and mice.
In these days, when bleeding is rarely resorted to, it is difficult to
obtain human serum, and we have had to make the most of the small
quantities of serum we have succeeded in obtaining. We have
made, however, certain experiments upon dogs.
In mice of lo to 20 grammes the dose of human serum used was,
as a rule, from J to l c.c. ; in rats of 50 to 100 grammes it was
I to 2 c.c. If into a mouse of 20 grammes with T. hrucei in its
blood h to I c.c. of human serum is injected, one finds, at the end of
twenty-four to thirty-six hours, that the trypanosomes have dis-
. 1 Blanchard has also tried without success the effect of this drug upon the
trypanosome of nagana in the marmot.
- [Laveran has since shown (C. R. Acad. Sciences, v. 139, 1904, pp. 177-179)
that the serum of the baboon (Cynocephalus) has a similar eflect upon 7'. brucei (as
well as on T. evansi, T. cquinum, and T. ga/npiense), but that it is distinctly less
potent than human serum.]
^ Laveran, Acad, des Sciences, April i, 1902, and July 6, 1903 ; Laveran and
Mesnil, Ann. Inst. Past., November 25, 1902.
^ Compare this fact with others recorded by Halban and Landsteiner {Milnch.
mediz. Wochetischr., 1902, No. 12), who have shown that the maternal serum is more
hsemolytic, more bactericidal, etc., than the foetal.
NAG AN A 175
appeared from the blood. The same result is obtained in a rat
of 100 grammes, on injecting i to 2 c.c. of human serum.
The disappearance of the parasites is less rapid when they are
very numerous at the time of injection. Account must also be taken
of the difference in activity of serums. We have had serums which,
in doses of 5 and even ~j c.c, have caused the disappearance of the
trypanosomes from the blood of a mouse weighing 15 grammes.
It sometimes happens that the trypanosomes do not reappear, but
this is exceptional. Although we have treated a large number of
infected rats and mice with human serum, we have had only four
cases of cure in mice after one or two injections. Two of these
mice were reinoculated twenty -five and thirty days after they had
recovered, and contracted an ordinary trypanosome infection.
As a general rule, human serum causes only a temporary dis-
appearance of the trypanosomes from the blood, and after a variable
time the parasites reappear, and require a fresh injection of serum
to make them disappear again. In rats and mice with nagana the
trypanosomes often disappear f6r four to eight days, after one
injection of human serum ; and in some of our mice treated with
human serum the parasites disappeared from the blood for twelve
and even eighteen and nineteen days. When the trypanosomes have
reappeared in the blood of an animal undergoing treatment, they
rapidly multiply and swarm as in untreated animals, and death soon
follows if the serum is not injected again. .
In this way frequent injections of human serum will considerably
prolong the life of an animal suffering from nagana. In those cases
in which recovery has taken place it has always been as the result
of one or two injections, and it is noteworthy that animals which
had to be treated for a long time did not recover.
One might think that human serum frequently injected into an
infected animal would lose its effect upon the trypanosomes. That
is indeed so, but the diminution of activity occurs only very slowly,
so that an animal may be successfull)- treated in this way for two or
three months.
Usually in animals treated with human serum we have waited
for the reappearance of the parasites in the blood before giving a
fresh injection, but sometimes we have made the injections every
two or three days without waiting for the parasites to reappear. We
have not obtained better ultimate results by so doing.
Animals tolerate these injections of human serum quite well ;
thus we have injected, without any ill effects, as much as 2 c.c. into
a mouse weighing 15 grammes. In rats and mice the injections are
made under the skin or into the muscles of the shoulder, with the
usual antiseptic precautions. With a human serum of good quality
it is quite easy to prolong the life of rats and mice for two months,
control animals untreated dying of the disease in four to five days.
In some cases animals have survived for three months when treated.
By injecting arsenious acid and human serum alternately we
176 TRYPANOSOMES AND THE TRYPANOSOMIASES
have obtained still more favourable results. A rat lived 127 days
and a mouse T03 days ; but we have obtained no cures by using
these two substances, either alternately or simultaneously.
Mode of Action of Human Serum. — It is difficult to study in vitro
the action of human serum upon the trypanosome of nagana, because
the movements of this trypanosome very rapidly become sluggish.
On mixing equal parts of trypanosome-containing blood and human
serum the trypanosomes become less active at the end of half to one
hour, and as a rule they are motionless at the end of two to three
hours ; but practically the same thing happens in blood which has
not been mixed with human serum. The action of human serum
upon these trypanosomes is not sufficiently rapid to be studied
in vitro, as is that of arsenious acid.
Human serum does not agglutinate T. brucci, whereas the serums
of the guinea-pig, goat, sheep, and pig, which do not possess any
curative property, give rise to well-marked agglutination rosettes.
We see once again, therefore, that the agglutinating power may
exist without any microbicidal power.
On carefully examining the blood of animals treated with human
serum, the mode of action of the serum can be studied in detail.
The examination should be made at short intervals during the
twenty-four hours immediately following the injection of the serum
into a severely infected animal.
During the first few hours after the injection the trypanosomes
remain normal, but at the end of four to five hours it is seen that in
fresh blood, and, better still, in stained preparations, many of the
trypanosomes are changed in shape, and have assumed a tadpole or
spherical form. Later on the protoplasm and the nucleus dis-
appear in those parasites undergoing involution. These changes
which the trypanosomes undergo are, therefore, similar to those seen
in animals treated with arsenious acid.
There is no marked leucocytosis. Leucocytes containing recog-
nisable remnants of trypanosomes (such as nucleus and centrosome)
are seen, but phagocytosis appears only to occur with trypanosomes
which are dead or markedly involuted. We see, therefore, that
human serum has a microbicidal effect upon the trypanosome of
nagana analogous to that of arsenious acid.
Human serum heated to 56° C. for one hour loses about one half
its power, but good results may, nevertheless, be obtained with it by
increasing the dose a little. A mouse treated only with serum which
had been heated to 56° C, lived for forty-three days. On heating
to 62° C, human serum becomes almost entirely inactive.
No doubt there is a close relation between man's immunity from
nagana and the microbicidal action of human serum upon T. brucei.
Probably the active principle of the serum is produced by the
leucocytes, which would account for the fact that the serum is more
potent than pleural fluid, and that ascitic fluid, which is very poor
in leucocytes, is almost inactive. In one experiment citrated human
NAG AN A 177
plasma was found on]y slightly active compared with the serum ; but
it is conceivable that human plasma may contain sufficient of the
active principle to protect the body against the invasion of the
trypanosomes without being Sufficiently potent to have a curative
effect when it is injected into animals, and is thus diluted with
a relatively large volume of inactive plasma.
Perhaps, also, the microbicidal substance of human serum is,
in the circulating blood, contained solely in the leucocytes, thus
rendering them able to destroy the trypanosomes of nagana. It was
of interest to ascertain whether repeated injections of human serum
into an infected animal might not give rise to the formation of an
antibody which would ultimately neutralize the active principle of
the serum. Experiments which have been made do not confirm
this hypothesis.
Normal Serum of Animal Origin. — The serum of none of the
lower animals has an effect upon the trypanosome of nagana at all
comparable to that of the serum of man.i The following serums
injected into rats or mice with nagana gave us negative results :
fowl, goose, horse, sheep, goat, and pig.
It is interesting to compare the action of monkey's serum upon
T. briicei with that of human serum. The serum of a Cercopithecus
was found to be inactive, which is in agreement with the marked
susceptibility of these monkeys to nagana. The serum of a chim-
panzee, even in doses of i c.c, had no effect upon the course of
the infection in a mouse.
The Serum of Animals Refractory to Nagana, after
Repeated Injections of Blood containing T. brucei. — We
have made repeated injections of trypanosomes into birds (goose,
fowl), but the curative power of the serum of birds thus treated has
always been nil. [Mesnil and Martin were able to confirm this
observation in the case of the geese which they found refractory to
nagana, surra, and caderas. The serum of a goose which contracted
a mild infection with nagana, from which it recovered, was found
equally inactive, although the goose had become immunized.]
The Serum of Animals which have acquired Immunity
against Nagana. — Nagana, which always runs a fatal course in a
large number of mammals, is less serious in certain species. Goats,
sheep, and cattle show a fairly large percentage of cures, and animals
so cured are immunized against nagana.
In this way we have cured {vide supra) a goat and two sheep.
After ascertaining that these animals had quite recovered and were
immunized against nagana, we made experiments to see whether
their serum possessed any curative properties. These serums were
only found active when mixed with blood containing T. brucei,"^ but
1 [But see footnote, p. 174, re the action of the serum of Cynocephalusi\
^ We may note once more that this shght activity as a rule disappears at the
end of a few days in serums kept in the ice-chest, contrary to what occurs with
human serum.
12
178 TRYPANOSOMES AND THE TRYPANOSOMIASES
on injection into infected animals they never arrested the march of
the infection. Similarly, they produced no effect whatever when
injected simultaneously with the infective blood, but into some other
part of the body.
We endeavoured to increase the immunity of the goat and sheep
by injecting very large doses of infective blood into them ; thus, the
goat received sixteen injections of dog's blood containing trypano-
somes (vide supra). Its serum, tested for curative power upon mice,
in doses of i and even 2 c.c, always gave a negative result.
[Martini, Schilling, and Kleine and Hollers succeeded in im-
munising animals against the Togo virus, and Diesing immunized
asses against the Cameroon virus. The serums of these immunized
animals had preventive and agglutinating properties, but were
rarely, if ever, curative. As the identity of these diseases with the
nagana of Zululand is questionable, the details of these observations
will be considered later (see second part of this chapter)].
In conclusion, we can say that arsenious acid, trypanred, and
human serum, are the only therapeutic agents which have any
appreciable effect in the treatment of nagana.^
Arsenious acid may be of use in prolonging the life of draught
animals, but, except in these special cases, its use cannot be
recommended. Animals thus treated are hardly ever cured, and,
moreover, may spread the infection amongst healthy animals, and
finally, it would be dangerous to give the large doses of arsenious
acid which are necessary to combat nagana to animals destined for
the food of man.
Human serum, which in our hands has quite cured several mice,
in most cases cannot do more than prolong the animal's life for a
time. Moreover, the treatment of large animals with human serum
is impracticable on account of the enormous doses of serum it would
be necessary to use.
Section 7. — Prophylaxis.
In order to protect animals against a microbic disease,
immunizing serums may be used, or the animals may be inoculated
with microbes of diminished virulence — that is, an attenuated virus —
so as to produce mild attacks of the disease, which lead to immunity.
In these two ways we have tried to immunize animals against nagana.
I. Attempts to prepare an Immunizing Serum. — Human
serum has slight preventive power against nagana. If one inoculates
into a mouse xo c.c. of infective blood mixed with yg- c.c. or more
of human serum, the animal does not become infected. Sometimes
infection is prevented when the virus and the serum are injected
simultaneously in different parts of the bodj', but in that case the
1 [This statement requires modification, for certain dyes, notably o-dichloro-
benzidine + aa'rf H, as well as one or two arsenic derivatives, notably atoxyl, have
given better results as regards prevention and cure than trypanred and arsenious
acid respectively (see Chapter XIII.).]
NAG AN A 179
result is not constant ; infection may occur after a slightly longer
incubation period.
If a rat be inoculated with i c.c. of human serum, and twenty-four
hours later with infective blood, the animal contracts the disease,
but the incubation period is prolonged, the trypanosomes appearing
in the blood at the end of five to nine days. On injecting T. bntcei,
together with blood from an animal which has been recently treated
with human serum, one finds in the same way that the incubation
period is prolonged, but once the trypanosomes appear in the blood
the disease runs its ordinary course.
Nagana has developed in mice inoculated with trypanosomes
which had been mixed with human serum and then washed ; there
was merely a delay in the appearance of the trypanosomes in the
blood. Mice inoculated with a mixture of infective blood and human
serum, in which an infection does not follow, do not acquire any
immunity against nagana.
The serum of the dog, sheep, goat, horse, fowl, or goose, mixed
with trypanosomes, does not prevent an infection occurring in
animals injected with the mixture, and, moreover, the incubation
period is not prolonged. This property of human serum seems,
therefore, to be peculiar to it.^
One might have hoped that the serum of animals which had
recovered from nagana, and were thus immunized against the disease,
would have possessed immunizing properties superior to those of
human serum. Here again our expectations have not been realized,
as the following observations show:-
The serum of a billy goat infected with nagana forty-seven days .
previously, and still suffering from the disease, showed slight
preventive power. Two mice inoculated with a mixture of iV c.c. of
infective blood and i or 2 c.c. of serum survived. The serum of this
goat was active, however, only when mixed with the infective blood
injected.
The serum of a nanny goat which had recovered from nagana, and
so acquired immunity against the disease, and which was frequently
injected with blood rich in trypanosomes (see p. 139), was tested
four to eight days after each inoculation. It was found to possess
only a very slight preventive power, comparable with that which it
rapidly acquires during the course of an infection. This power did
not increase, however, although the goat was reinoculated every
week with 30 to 40 c.c. of dog's blood. The serum of this
immunized goat, mixed in vitro with trypanosome-containing blood,
had no definite microbicidal action. On examining the mixture
kept for one to two hours at the room temperature, and then placed
^ [As has already been stated, Laveran has found that the serum of the baboon
has an action similar to that of human serum, but that it is distinctly less potent.]
^ [Martini, Kleine and MoUers, and Diesing have shown that the serums of
calves and asses immunized against the diseases of Togo and Cameroon, closely
allied to nagana, have preventive properties (see second part of this chapter).]
12 — 2
i8o TRYPANOSOMES AND THE TRYPANOSOMIASES
in the ice-chest for twenty-four hours, we found that the majority of
the trypanosomes were still living, but less motile. This serum,
therefore, behaved like a normal serum, and was no more aggluti-
nating than the serum of a normal goat.
This serum was only found active when mixed with the virus, and
even then only in the big dose of i c.c. for a mouse. In smaller
doses it merely prolonged the incubation period one or two days.
Serum injected twenty-four hours before the virus, or even at the
same time, but in some other part of the body, had no effect or
merely prolonged the incubation period one or two days.
We obtained similar results with the serum of the two sheep
which had recovered from nagana, and which had received, the one
six and the other three, inoculations of nagana blood. The serum
of the latter sheep protected a mouse in doses of | c.c. mixed with
the virus, and in doses of 2 c.c. inoculated in some other part of
the body.
According to Schilling, i cattle which have acquired immunity as
a result of repeated injections of infective blood furnish a serum
possessing microbicidal properties for T. brucei. He quotes the
following experiment : A bull which had apparently recovered from
an attack of nagana was injected subcutaneously with ig c.c. of
defibrinated horse blood containing numerous trypanosomes. On
the ninth day after injection a few trypanosomes were found in the
blood of the bull, and they had disappeared by the twelfth day. A
fresh injection of trypanosomes was given intraperitoneally, and it
was then found that the serum of the bull had a specific action
in vitro upon the trypanosomes of nagana, which became motionless
thirty and even twenty-one minutes after being mixed with this serum.^
Nocard was not able to confirm this observation. He inoculated
into a cow in one week 852 c.c. of blood from a cat or dog very
rich in trypanosomes. The serum was found to have a marked
agglutinating effect upon the trypanosomes, but was not microbicidal.
In vivo this serum, mixed with trypanosome-containing blood, very
appreciably delayed the appearance of the parasites in inoculated
mice, but unless used in mixture it had no effect.
The serum of this cow^ actively immunized against nagana was
therefore only slightly prophylactic, although attempts were made
to increase the immunity by means of intraperitoneal injections of
blood rich in trypanosomes. None of the mice used in this series
of experiments had acquired any resistance whatever to the virus.
The serum of a fowl and goose which had been injected with
1 Schilling, Centralb.f. Bakter., I, v. 31, 1902, p. 452.
2 [We shall see later that Martini, Kleine and MoUers, and Diesing have
succeeded in obtaining similar results.]
^ This cow, like the one mentioned on p. 137, showed a rise of temperature to
40"8° C. [io5'4° F.] three days afier inoculation, and several trypanosomes were
seen on microscopical examination. The next day the temperature was normal
again. Krom that day the cow received enormous doses of virulent blood. It
remained, however, in excellent condition, and its blood was not virulent for more
than two months.
NAGANA i8i
blood rich in trypanosomes showed very slight, if any, preventive
power, as the following experiment shows : A mouse inoculated with
I c.c. of serum of an inoculated fowl mixed with infective blood
lived for fifteen days, whereas a control mouse died in a week. The
trypanosomes inoculated in this experiment, however, were only
slightly motile at the time of injection.
[Even the goose which Mesnil and Martin "^ succeeded in infecting
with nagana did not, after its recovery from the infection, furnish a
prophylactic serum. Mice inoculated subcutaneously with f c.c. of
goose serum mixed with trypanosomes did not live longer than
control mice.]
The serum of rats with nagana which had received from three to
seven injections of arsenic showed only slight preventive properties.
We have observed, as Bruce had done, that arsenic has no preven-
tive action whatever upon nagana. Animals treated with arsenic as
a prophylactic become infected quite as easily and as quickly as
control animals, and the course of the disease is not altered in any
way.
2. Attempts to produce Attenuation of the Virus. — We
have tried in several ways to attenuate the virulence of T. brucei.
The blood of animals suffering from nagana very rapidly loses its
virulence when kept on ice or at the room temperature. At the end
of several hours the trypanosomes become much less active, -while
at the end of twenty-four hours most, and sometimes all, of them
are motionless.
When such blood is inoculated the incubation period is consider-
ably longer than when fresh blood containing very active parasites
is injected ; but the alteration in the trypanosomes has no other effect
upon the course of the disease. From the time that the parasites
appear in the blood of inoculated animals they develop with the
usual rapidity, and the disease loses none of its severity.
We have experimented with blood heated to different tempera-
tures and for variable lengths of time. On examining blood rich
in trypanosomes, which has been heated for an hour to 41° C, it is
seen that the parasites are motionless, deformed, and spherical.
Blood thus heated gives rise to an infection after a markedly
increased incubation period, but the disease is just as severe as usual.
A more prolonged exposure to 41° C. or a shorter exposure to a
temperature of 44° C. kills the parasites. We see, therefore, that
by heat it is not possible to attenuate the virulence of nagana, or,
rather, that attenuation of the virus results only in a prolongation of
the incubation period.
We have seen (p. 160) that the trypanosomes in Novy and
McNeal's cultures ceased to be virulent some days before they died.
This loss of virulence was produced in forty-eight hours on heating
to 34° C. cultures grown at 25° C. Mice inoculated with these non-
' [Mesnil and Martin, C. R. Soc. Biol., v. 60, 1906, p. 739.]
i82 TRYPANOSOMES AND THE TRYPANOSOMIASES
virulent trypanosomes were almost as susceptible to virulent para-
sites (even although slightly attenuated by culture) as control mice.
The virulence of T. brucei may be diminished by mixing a i per
cent, solution of toluidin blue with the blood of an infected animal.
Animals inoculated with this mixture show a longer incubation
period than animals inoculated with the blood alone.
In two rats inoculated with a mixture of 8 parts of trypanosome-
containing blood and i part of toluidin blue, which was allowed to
stand twenty minutes after mixing, trypanosomes appeared in the
blood only on the seventh or eighth day. In a guinea-pig inocu-
lated with a mixture of infective blood and i per cent, toluidin blue
(injected two minutes after mixing) the parasites did not appear in
the blood until the twelfth day.
As a general rule, the diminished virulence of the trypanosomes
is shown only by this increase in the incubation period, for the
disease, once it has declared itself, runs a normal course. There are,
however, exceptions.
In a mouse inoculated with a mixture of trypanosomes and
toluidin blue the parasites appeared only on the eighth day after
inoculation, and the disease ran quite an unusual course. In a rat
similarly inoculated trypanosomes appeared in the blood on the
fifth day after inoculation, and permanently disappeared at the end of
three to four days. This experiment is quite unique for nagana in
rats. The rat which thus suffered from a mild form of the disease
was not immunized by it.
This last experiment resembles those cases of reinfection in mice
cured of nagana by means of human serum (p. 175). It seems
proved that an attack of nagana induced by an attenuated virus or
modified by treatment is not sufficient to confer immunity. We
have observed immunity against nagana only in those animals
(goat, sheep, cow) which, after a prolonged infection, have been
cured spontaneously. From this it may be concluded that it is
difficult to immunize animals against nagana by injecting into them
trypanosomes of diminished virulence, and so producing in them a
mild attack of the disease.^
Preliminary inoculations with infective blood kept for several
days on ice or for several hours above 40° C, or kept for a time in
contact with a dye by which the virulence is destro3'ed, do not
prevent an infection resulting from the injection of a fresh or of an
attenuated virus under the conditions we have just mentioned, and
do not in any way modify the course of the disease.
1 A female rat, inoculated September 23, 1902, and treated alternately with
human serum and arsenic starting from September 25, gave birth on October 14 to
seven well-developed young ones, which she reared. On November 10 the young
rats were able to eat. Two of them were inoculated subcutaneously with infective
blood at the same time as two young ones of about the same weight born of a
healthy rat. The four young rats showed the same susceptibility to nagana, which
was a little greater than that of adult rats.
NAGANA 183
We shall see (pp. 191 and 195) that Koch and Schilling have
tried to attenuate for cattle the virulence of trypanosomes allied to
that of nagana, by passing these parasites through different species
of animals, and that they claim to have obtained certain favourable
results in this way.^ The facts quoted by these authors do not
appear to us to be conclusive. Koch is said to have obtained his
' vaccine ' by two passages only — the first through the rat, the second
through the dog.
We cannot form any definite conclusion from the cure of Koch's
two oxen, for it is by no means rare for cattle to recover spon-
taneously from nagana and surra, and animals which so recover are
immune, as were Koch's cattle.
In his first paper Schilling stated that he had vaccinated two
calves by inoculating them with a virus of the third passage through
dogs. But he very quickly recognised that two or even three
passages through the dog or rat were not sufficient to attenuate the
virus for cattle ; and in his paper, published in January, 1903, he
speaks of a virus which had been passed seven times alternately
through the dog and rat, then from eighteen to twenty-one times
through dogs alone. That is a very different thing from the two
■ passages of Koch. Thirty-six oxen were inoculated with this virus,
each one on two or three occasions, with the result that they
contracted a mild and temporary^ infection, and were then taken
into a fly area. What happened to these cattle we shall see in the
second part of this chapter.
This process, as Schilling himself acknowledges, is useless for the
vaccination of horses.
According to our own observations the virulence of T. brucei may
be slightly attenuated by passage through different species of animals,
but the trypanosome loses little of its virulence in passing from one
animal species to another, and in all cases rapidly regains its viru-
lence, as the following experiment shows :
On April 24, 1902, a dog was inoculated with the blood of a sheep
infected with nagana for six months. On May i trypanosomes had
' appeared in the dog's blood. On May 2 one rat and two mice were
inoculated subcutaneously with several drops of the dog's blood con-
siderably diluted with citrated salt solution. On May 4 parasites appeared
in the blood of the rat and mice ; on the 6th they were very numerous,
and all the animals were found dead on the morning of the 7th.
^ [Martini's experiments on the same lines seem to have been to some extent
successful. Diesing has obtained from immunized asses a serum which is able to
produce a temporary passive immunity in animals, sutBcient to enable them to pass
through a fly belt.]
^ About half these cattle showed parasites in the blood ten days after inocula-
tion. At the end of the first month microbicidal properties were found to be present
in the serum of five out of eight cattle examined from this point of view. The
trypanosomes in the peritoneal exudate of an infected dog, mixed with an equal
volume of ox serum, were killed by the serum in twenty minutes. We have already
quoted a similar result, p. 180.
i84 TRYPANOSOMES AND THE TRYPANOSOMIASES
Trypanosomes which had been passed through the sheep and
then through the dog thus gave rise in a rat and in mice to infections
just as acute as those produced by parasites inoculated direct from
rat to rat or from mouse to mouse.
It is possible, however, that attenuation of the virus for a
particular species of animal may be produced as a result of numerous
passages through another species. That is, perhaps, the case with
the virus we have used in our experiments. Although cattle suffer
severely from nagana in Africa, our virus, inoculated by Nocard into
three cows, produced in them only a mild infection. It may be due
to the difference in race of the cattle, but it may also be due to
attenuation, resulting from the innumerable passages through
different mammals other than ruminants, which the virus has
undergone since 1896, when it was imported from Zululand into
Europe. It would be very important to test the virulence of
these trypanosomes, which we have at the present moment under
observation, upon South African cattle. It is just possible, if our
second hypothesis is correct, that this virus has become a vaccine
which might be used in Africa to protect cattle against the natural
infection.
In conclusion, we must admit that hitherto we have succeeded
no better in preventing nagana than we have in our attempts to cure
it, but we must not regard the conclusions at which we have arrived
as final. We hope to continue our investigations, and no doubt
other observers will do the same. Perhaps experiments made with
other animal species than those which we have had at our disposal
might yield better results. It would be interesting, for example, to
experiment upon African antelopes or buffaloes, which, although
often infected with nagana, are very resistant to the disease. Such
experiments could only be carried out in Africa.
In the actual state of our knowledge we may say that we are
not acquainted with a certain and practical remedy for nagana,
nor with any reliable process of immunizing animals against the
disease.
[The experiments of Thomas with atoxyl, and those of Mesnil
and Nicolle with atoxyl and various benzidine derivatives, are a step
in the right direction. Mesnil and Nicolle were able to prevent, as
well as cure, an infection of nagana in mice with atoxyl and a
particular derivative of benzidine. Possibly these drugs will be
found useful in the prevention and treatment of nagana in cattle and
horses. Full reference to these experiments is given in Chapter XIII.,
on Treatment.]
Prophylactic measures intended to limit the areas in which
nagana is endemic, and to prevent its introduction into countries
still immune, are therefore of considerable importance. The dan-
gerous areas should be mapped out accurately. This is relatively easy,
because we know that it is only certain species of tsetse-fly which
CLASSIFICATION OF THE TRYPANOSOMIASES 185
propagate the disease ; but it would be as well to find out exactly
which species of tsetse convey the parasite, by fresh experiments on
the lines of Bruce's.
The invariable result of the civilization of a country is to destroy
or to drive away the big game. In this way, then, we may hope
that the areas of nagana will become narrowed in proportion to the
advance of Europeans into the African continent, of which until
recently only the coast regions were known, but which is already
being intersected at various points by railways into the interior. In
fact, Foa and Theiler have already observed that the destruction of
the big game has rendered the fly areas more healthy. At the
present moment, at any rate, there is no question of attempting to
exterminate the fly.
When the fly and nagana areas are well known, it is often
possible to take effective precautions, if it is merely a question of
passing through those areas. Perhaps the best precaution is to
travel only at night, as the tsetse-fly does not, as a rule, bite at
night. [Diesing recommends injecting the serum of highly-
immunized animals, by which a temporary passive immunity is
produced, sufficient to allow the susceptible animals to pass through
the fly belt. He obtained fairly good results with cattle in this way.]
Then, it has been recommended to rub different substances, par-
ticularly creolin, over the animals one wishes to protect. In the
hinterland of Togo the natives rub the juice of a plant, Amoiimm
melegueta, over the animals, in order to protect them against the
bite of the tsetse. Smoke drives away the flies, and may be used,
for example, in encampments. Good results have been obtained by
placing horses in boxes in which the apertures are closed with
gauze, or in stables in which horse manure is constantly burnt. ^
Precautionary measures are, or should be, taken by the sanitary
authorities to prevent the importation of nagana, particularly in fly
districts which are free from the disease. (See Prophylaxis of Surra,
p. 284.)
AFRICAN DISEASES ALLIED TO THE NAGANA OF
ZULULAND.
[Section 1.— General Considerations. Classification of the Try-
panosomiases. Methods of Diffepentiating- and Identifying
the Pathogenic Trypanosomes.^]
[The African trypanosomiases, which resemble the nagana of Zulu-
land more or less closely, may be divided into two groups — those occurring
in districts where tsetse-flies are found, and which are probably spread by
means of these flies, and those occurring where the tsetse-fly is absent
and which are probably spread by other biting flies, such as Tabanidae or
1 A Report by Pitchford, of Natal, analyzed in Bull. Soc. d'Hudes colon.,
June, 1903.
2 [The whole of this section, down to p. 190, has been added. — Ed.]
i86 TRYPANOSOMES AND THE TRYPANOSOMIASES
Stomoxys. In the first group would come the trypanosomiases of cattle
and pigs in German East Africa (described by Koch, Ochmann, and
others) ; of dromedaries in Ogaden, Somaliland (Brumpt, Theiler) ; of
donkeys, mules, and cattle in the Anglo-Egyptian Sudan (Balfour,
Head) ; of cattle, mules, and dogs in British East Africa, Uganda, and
adjacent territory (Stordy, Bruce, Nabarro, Greig, and Gray) ; of cattle
in the Congo Free State (Broden) ; of Equidae and cattle in Cameroon
(Ziemann, Diesing) ; of cattle and horses in Nigeria (Christy, Hewby,
Moore) ; of cattle and horses in Togo (Koch, Schilling, Ziemann,
Martini) ; of oxen in Sierra Leone (Smith) ; and perhaps a trypano-
somiasis of horses in French Sudan (Cazalbou). The second group
would include the Zusfana disease of horses in Algeria (Szewzyck, Rennes,
Roger and Greffuhle) ; Dehah, a disease of dromedaries in Algeria
(Sergent) ; Mhori, a disease of dromedaries in French Sudan and
Timbuctoo (Cazalbou) ; Sotmia, of cattle and horses in French Sudan
(Cazalbou) and in Guinea (Martin) ; the trypanosomiases of cattle and
Equidas in Erythrea (Memmo, Martoglio, and Adani) ; of cattle and horses
in Abyssinia (Savoure and others) ; of cattle, sheep, and goats in Cameroon
(Ziemann) ; and of oxen and Equidae in Haut and Moyen-Niger (Pecaud).]
[In the present state of our knowledge it is impossible to speak
with certainty about the nature of many of these diseases. Some of
them have been called nagana, others surra, and others again, such
as Souma, are thought to be distinct diseases. The fact that certain
of these diseases occur in tsetse-infested districts, while others are
found in the absence of the tsetse, suggests the classification adopted
above into the ' tsetse group ' of trypanosomiases and those not
dependent on the tsetse for their transmission. Many of the latter
may eventually prove to be varieties of surra. This has been shown
by Laveran to be the case with mbori. It is extremely probable
that further investigation may show that nagana and surra are not
two individual diseases, but rather two distinct groups of diseases,
the one group (nagana) being dependent on the tsetse-fly for its
transmission, the other (surra) on Tabanidse, Stomoxys, or other
biting flies.]
[The subject is rendered all the more difficult by the fact that
the trypanosomes of these various diseases present only very slight
morphological differences. These differences between the various
trypanosomes are not greater than those seen in the same trypano-
some in the blood of different animal species. Sometimes, indeed,
one finds greater morphological differences in the same trypanosome
in the various species of animals than are found between the
trypanosomes of nagana and of surra. This has led Koch and many
other German authorities to regard nagana and surra as identical.
This view of Koch, Musgrave, and others, is almost certainly
erroneous, as various recent methods of differentiating trypanosomes
prove ('cross-immunization' experiments, cultivation of the respective
trypanosomes, etc., see later). Moreover, as a result of his recent
researches in German East Africa on the development of trypano-
somes in Glossina — results which can, however, be interpreted other-
wise than Koch has done — Koch appears to be modifying his original
DIFFERENTIATION OF THE TRYPANOSOMIASES 187
views, and to regard at least T. hrucei and T. gambiense as distinct
species.]
[Koch's Classification of Trypanosome Diseases. — Koch 1 divides the
trypanosome diseases into two groups :
Group I., including the trypanosomiases of rats and of cattle (Theiler).
In these the trypanosomes are constant in their more important characters,
and are sharply separated from the other mammalian trypanosomes. The
most important properties, according to Koch, are (i) the morphological
characteristics, (2) the virulence, and (3) their relations to the domestic
animals. The trypanosomes in this group are said to be constant in all
these characters, and to show no variation. This is not absolutely true,
however, for several observers have shown that the virulence of T. lewisi
for rats may vary.
Group II. includes human trypanosomiasis, nagana, surra, and mal de
caderas, but no mention is made by Koch of dourine or of the Gambian
horse disease. These trypanosomiases are said to be in a stage of
mutability. In the three important properties mentioned above the
trypanosomes are fluctuating and variable ;. thus they are not sharply
differentiated morphologically from each other, their virulence fluctuates
over a wide range, and they are not found exclusively in one host. From
this Koch argues that they are not yet developed into distinct species.]
[Methods of Differentiating and Identifying the Pathogenic Trypano-
somes. — Attempts have been made by different observers to differentiate
these trypanosomes by their morphology — e.g., by the presence or
absence of vacuoles or of chromatic granules in the protoplasm, the
length of the body and of the free flagellum, the shape of the
posterior end, and so on ; but it has been pointed out that such
variations may occur in the same trypanosome, consequently they
are valueless in the determination of species.]
[i. Animal Inoculations. — The morphological characters failing to
differentiate these trypanosomes, the next step was to inject the
parasites into various species of animals. In certain closely allied
diseases, such as nagana, surra, and several other less definite African
trypanosomiases, the effects produced in animals are not sufficiently
characteristic to enable us to state, from animal inoculations alone,
that these are distinct morbid entities. But some results of animal
experiments are fairly constant — e.g., nagana in rats and mice is
usually very rapidly fatal, and at death the blood generally swarms
with trypanosomes, while T. gambiense sometimes fails to infect these
animals altogether, and the trypanosomes are never so numerous as
in nagana ; dourine produces characteristic cutaneous ' plaques,'
which are rarely seen in the other trypanosomiases.]
[Animal inoculations are made subcutaneously, intraperitoneally,
or intravenously, an infection usually following any of these pro-
cedures. Dourine is to be distinguished from the other trypano-
somiases by the fact that infection may occur — both naturally and
experimentally — through intact mucous membranes.']
[2. 'Cross-Immunization' Experiments (Laveran and Mesnil). —
This method has been used with success by Laveran and Mesnil for
' [R. Koch, Deutsche med. VVoehenschr., November 17, 1904, pp. 1705-1711 ;
translation in Brit. Med. Journ., November 26, 1904, pp. 1445-1449.]
i88 TRYPANOSOMES AND THE TRYPANOSOMIASES
differentiating several of these trypanosomiases. In this way they
showed the individuaHty of surra, of nagana, of caderas, and of
Gambian horse disease ; also the identity of Indian and Mauritius
surra and mbori. Nocard and Lignieres found that dogs immunized
against dourine were as susceptible to nagana and caderas as normal
animals.]
[This method is rather long and tedious. Resistant animals,
such as sheep, goats, and calves, must be used as a rule, and it takes
a long time for these animals to recover from their chronic infection,
and to become immunized. When their blood, on inoculation into
small animals, is found to be no longer infective, the original
trypanosome, on reinoculation, does not give rise to a fresh infection
(or sometimes there may be a slight transient blood infection),
whereas a different species of trypanosome produces the same effect
as it does in a normal animal.]
[Koch {loc. cit.) has criticised this method of differentiating trypano-
somes, and has stated that the experiments upon which Laveran and
Mesnil base their opinions are inconclusive, for the following reasons :
(i) The experiments were made upon goats, which are only slightly
susceptible to surra, and therefore ill adapted to the study of the disease.
(2) Animals which appear to have acquired immunity against a trypano-
somiasis retain the parasites for long periods in their blood, and if the
blood of a goat immunized against nagana, and subsequently inoculated
with surra, becomes again virulent, it is perhaps because the animal is
still infected with nagana. (3) The fact that animals immunized against
one trypanosome are susceptible to a trypanosome from another source
does not show conclusively that these parasites are different species,
animals which resist a variety of trypanosomes of feeble virulence being
capable of infection by a more virulent variety of the same trypanosome.]
[Laveran and Mesnil 1 have answered these criticisms of Koch as
follows : (i) In order to obtain animals immunized against surra or
nagana it is, of course, impossible to employ species in which these infec-
tions are always fatal. One is, therefore, obliged to use animals, such as
goats, in which these trypanosomiases may end spontaneously in recovery.
Moreover, surra and nagana do not produce in goats such mild infections
as Koch seems to think, and several goats died during the course of the
experiments. Further, these goat experiments have been confirmed by
others with bovines. Vallee and Carre ^ have shown that a cow immunized
against nagana was susceptible to surra. Vallee and Panisset^ immunized
bovines against surra, and found that they were then not susceptible to
mbori.]
[The same method has given good results with other trypanosomiases,
and goats were not the only animals used. A goat and sheep immunized
against nagana were as susceptible to caderas as normal animals.* An
ox, sheep, and pig immunized against caderas were normally susceptible
to nagana (Ligniferes).^ Lastly, dogs immunized against dourine were
as susceptible to nagana and caderas as normal dogs (Nocard and
Ligniferes)."]
^ [Laveran and Mesnil, C. R. Acad. Sciences, v. 140, March 27, 1905, p. 831.]
2 [Vallee and Carre, Ibid., October 19, 1903.]
^ [Vallee and Panisset, Jbid., November 21, 1904.]
* I Laveran and Mesnil, Jbid., November 17, 1902.]
^ Lignieres, Bol. Agricolt. y Ganad., Buenos Aires, February i, 1903.]
•^ [ Nocard, Soc. Biol., May 4, 1901 ; Ligniferes, Riv. Soc. med. Argent., v. 10,
1902, pp. 112-114]
DIFFERENTIATION OF THE TRYPANOSOMIASES 189
[(2) Koch's statement that animals apparently cured of a trypanosome
infection, and which have thereby acquired an apparent immunity, may
nevertheless retain trypanosomes in their blood for a considerable time is
quite true, but it is the exception, not the rule. Thus as much as 50 c.c.
of blood from such an animal has been injected into dogs without pro-
ducing an infection, which proves that the blood cannot have contained
any trypanosomes. Laveran and Mesnil showed also that the blood of
rats immunized against T. lewisi, as the result of an attack of this
trypanosomiasis, was no longer infective.]
[(3) The statement that an animal which has resisted a feeble virus
sometimes becomes infected when inoculated with a stronger virus'of the
same species is also true, but this again appears to be the exception rather
than the rule. Laveran and Mesnil forestalled this objection by inoculating
the ' weaker ' virus into animals immunized against the ' stronger ' virus.
Thus their goat immunized against nagana became infected with surra ;
so also did Vallee and Carre's bovine, although the Zululand nagana
experimented' with is undoubtedly more virulent than Mauritian surra.J
[3. Serum - Diagnosis. — The ' cross-immunization ' method of
diagnosis being a long and tedious one, and the practical difficulty
of always having immunized animals available being great, Laveran
and Mesnil ^ have attempted to elaborate a method of serum-
diagnosis. They had found previously ^ that the serum of sheep
cured of nagana had an action upon T. brucei, but not upon
T. equinum. Similarly, Kleine and Moellers^ have shown recently
that the serum of a donkey, which had a considerable action upon
Martini's Togo virus, is without action upon T. gambiense.]
[Laveran and Mesnil used the serums of three cured goats : one
(N) cured of nagana (Zululand), another (NS) of nagana and of
Indian surra, and the third (S) of Mauritian surra, then of the
Annamese horse trypanosomiasis (see Chapter VIII.). The usual
method was to mix the serum with the virus, in vitro, one or
two minutes before injecting subcutaneously into mice. The serum
of goat N, in doses of o'l to o'5 c.c, completely protected the mice
from nagana ; even dried serum kept for two months was found to
be protective. When injected apart from the virus, either twenty-
four hours before or at the same time, this serum was much less
active. The serum had little or no action upon the virus of caderas,
of Indian surra, of Annam, and of Togo. We may add that goat N
was inoculated with Schilling's Togo virus, to which it succumbed in
a month.]
[Similar results were obtained with the serums of the other two
goats. Laveran and Mesnil conclude that such serums acquire
specific properties, which can be used as a means of identifying
trypanosomes. There are, however, certain fallacies* which con-
siderably diminish its value as a means of diagnosis. Bearing in
1 [Laveran and Mesnil, C. R. Acad. Sciejices, v. 142, 1906, p. 14S2.]
2 Laveran and Mesnil, Ibid., v. 135, 1902, p. 838.]
^ [Kleine and Moellers, Zeitschr. f. Hyg., v. 52, 1905, p. 229.]
* [The serum of goat N in one experiment had an action upon the surra
trypanosome. The serum of goat S immunized against Mauritian and Annamese
surra had very little action upon the trypanosome of the latter.]
igo TRYPANOSOMES AND THE TRYPANOSOMIASES
mind these fallacies, Laveran and Mesnil think it follows from their
experiments that (i) the Annamese trypanosomiasis is different from
the Indian ; (2) Schilling's Togo virus is not nagana, but a species
of trypanosome very virulent for goats, killing them in one to two
months ; and (3) Martini's virus is neither nagana nor surra.]
[4. Cultural Characteristics. — We have seen that T. lewisi and
T. brucei, when grown artificially on Novy and McNeal's medium,
show considerable differences (T. Uwisi is much more motile, forms
large colonies of rosettes, flagella are directed towards the centre, etc. ;
T. brucei is less active, has an undulating membrane, colonies are
small, etc.),' by which these two trypanosomes can be easily dis-
tinguished (see pp. 79, 161). Novy, McNeal, and Hare have
cultivated the Philippine surra trypanosome, and find that the
cultures differ from those of T. brucei in several important respects.]
[5. The ' Precipitin ' Reaction. — Mayer has found (see p. 150)
that a specific precipitin is present in the serum of nagana animals,
and he thinks that this reaction may be a means of diagnosing allied
trypanosomes.]
[6. Fly Experiments. — Koch suggests that the different evolution
forms of trypanosomes seen in the appropriate species of Glossina
may be a help in diagnosis. It must be remembered, however, that
a certain percentage of 'fresh' flies may harbour 'wild' trypanosomes,
and Novy and Minchin are of opinion that some of Koch's ' evolution '
forms of T. brucei and T. gambiense have no relation to these parasites,
but are trypanosomes peculiar to the tsetse.]
[Nabarro and Greig, by dissecting flies — Glossina and Stomoxys —
at varying intervals after feeding on infected animals, found that
trypanosomes from various sources (human trypanosomiasis, Uganda
cattle disease, Abyssinian dog disease, and Uganda mule disease)
remain actively motile in the stomach-contents of flies for very
different lengths of time (see Section 8). This may prove to be a
means of differentiating species of trypanosomes, where live tsetse-flies
are to be obtained.]
[7. ' Chromo-Therapeutic' Reactions. — 'Mesnil and Nicolle, Wenyon,
and Aubert have made numerous observations upon the action of
various dyes in animals inoculated with different pathogenic trypano-
somes (see Chapter XIII.). From the results obtained it seems
probable that the ' chromo-therapeutic ' reaction will be a means of
differentiating the pathogenic trypanosomes.]
Section 2. — Trypanosomiasis of German East Africa.
It is to Koch^ that we are indebted for the earliest accounts of
the trypanosomiasis of German East Africa. He observed it there
in 1897, and found that it affected chiefly cattle. The incubation
' Koch, ' Reiseberichte,' etc., Berlin, 1898, pp. 65-73, 87, 88, and Deutsches
Kolonialblail, No. 24, 1901. Stuhlmann has published a map giving (i) the exact
areas in which the disease has been found ; (2) the routes along which herds of
cattle have become infected. The disease exists in the region of the heights of
TRYPANOSOMIASIS OF GERMAN EAST AFRICA igi
period is from nine to twelve days. At the outset the disease is
manifested by a rise of temperature and the appearance of the
heematozoa in the blood; then the animal becomes weak, anaemic, and
thin, and death occurs more or less rapidly. Nearly all the cattle die.
According to Sander,i this trypanosomiasis of cattle may present
itself in an acute or chronic form.
Veterinary Surgeon Schmidt^ states that the incubation period
is from five to six weeks. The presence of the parasite in the blood
coincides with the rises of temperature. The number of parasites,
the condition of the animal, and the amount of work it is made to
do, all help to affect the course of the disease. Cattle which are
allowed to be idle may live for years, whilst those which work
suffer from a very acute form of the disease. Cattle are more
susceptible than mules.
Koch made a certain number of experiments during his short
stay in the German colony. We reproduce here .those of his
experiments which he quotes in support of his method of vaccina-
tion, already mentioned (p. 183).
Blood containing many trypanosomes from a spontaneously
infected ox was inoculated into the following animals :
Result.
Remained healthy.
Died in 39 days.
,, 41 and 49 days.
Remained healthy.
■ ■ ■ )) 5)
Died in 34 and 52 days.
„ ig days.
The blood of one of the two rats in the previous experiment was
inoculated into :
One rat, which died in 68 days (trypanosomes in its blood 13 days after
inoculation), and one dog, which died in 42 days.
The blood of the dog was inoculated into :
Two dogs, which died in 19 and 26 days.
Three rats, which died in 67, 73, and 80 days.
Four Masai donkeys, which remained well.
Two oxen, in which the parasites appeared from the loth to the 13th
day, and remained present for 3 to 4 weeks ; after that they were no
longer seen. The oxen were cured and were immune. They had shown
no sign of illness at any time.
Usambara (northern boundary of the colony near the sea) ; in the region of Dar-es-
Salaam and the island of Mafia ; from the sea (the disease, perhaps, exists on the
island of Mafia itself, according to Panse, Zeitschr. f. Hyg., v. 46, 1904, p. 376) to
Usagara and along the whole valley of the Ruaha ; opposite Kiloa ; in the valley
of the Rovuma, which serves as the southern boundary of the colony, from the sea
right up to Lake Nyassa ; and finally, quite in the interior along Lake Tanganyika,
in latitude about 5° S.
1 L. Sander, Deutscher kolon. Kongress, 1902.
^ Schmidt, in Stuhlmann, ' Ber. lib. Land. u. Forstwirtschaft in Deutsch-
Ostafrika,' v. I, June, 1902, p. 137.
Animal.
Dose.
I Masai donkey . . .
5C.C.
I cow
5 >.
2 calves ...
5 ..
2 monkeys (sp. J,)
4 ..
2 guinea-pigs
2 ,,
2 rats
2 „
I dog
5 ..
192 TRYPANOSOMES AND THE TRYPANOSOMIASES
We have seen that Koch regarded this experiment with cattle as
the basis of his method of vaccination against nagana.
These statements of Koch relative to the immunity of Masai
donkeys (or Masai and Muscat hybrids) have been received with a
certain amount of scepticism, although Koch has founded his state-
ments upon current opinion as well as upon his experiments.
The objection has been raised that he simply placed blood
containing trypanosomes in contact with an abrasion on the ears of
the donkeys, a method of inoculation which is not infallible.
Since then Koch's statements have been disproved by means of
more exact experiments. Stuhlmann^ has seen trypanosomes in
the blood of sick Masai donkeys at Mombo, at the foot of the
heights of Usambara. Kummer^ has observed a heavy mortality
amongst the donkeys of German East Africa whenever they
have been taken into fly areas, and he has found trypanosomes in
the blood of the sick animals. He adds that the differences in race
of the donkeys used in this district are not recognisable by a
European. Grothusen^ also states that Masai donkeys are
susceptible to nagana. He rubbed some blood from one of these
donkeys into a wound on the ear of a zebra. The zebra died
seventeen days later, after showing symptoms of nagana, and with
many trypanosomes in its blood. This result, confirmed by that of
Martini, obtained with a virus coming from Togo, is important, for
it proves that the zebra, which has been regarded as refractory to
the African trypanosomiases, is susceptible to these diseases.
The various experimental data given by Koch show a consider-
able difference in the virulence of the German East African and
Zululand parasites. For example, we see that monkeys and guinea-
pigs are refractory, or only very slightly susceptible ; that in rats the
disease is very chronic, instead of fatal in a few days ; and that the
disease in dogs is also more protracted than is the nagana of Zululand.
As to the morphology of the trypanosome, we possess only a very
diagrammatic drawing which Koch has published in his ' Reiseberichte '
sufficient to differentiate it from T. lewisi, which Koch had in his mind
at the time, but not for a critical comparison with T. fo'MCgj of Zululand.
Further observations are obviously necessary before we can come
to a definite conclusion as to the relation between the nagana of
Zululand and this disease of German East Africa.
It would appear that Glossina morsitans carries the infection.
[Koch has since made a further study of this East African
disease, and considers its trypanosome to be T. brucei. It was with
this trypanosome that he made the observations on the evolution of
the parasite in Glossina, mentioned on p. 156. He states that in
German East Africa this trypanosome is carried by Gl. morsitans,
Gl. pallidipes, and especially by Gl. fusca].
1 Stuhlmann, loc. cit.
2 Kummer, Tropenpflanzer, 1902, No. 10, pp. 525, 526.
3 Grothusen, Archiv f. Schiffs u. Tropenhyg., v. 7, August, 190,3, p. 387.
TRYPANOSOMIASIS OF TOGOLAND 193
[A natural infection of pigs has been observed by Ochmann in
German East Africa, but whether it is true .nagana or an allied
disease is uncertain (see p. 114).]
Section 3, — Trypanosomiasis of Tog'oland.
The existence of a trypanosomiasis in Togoland was recognised
by Koch, who in 1895 examined in Berlin two specimens of the
blood of a horse coming from this German colony on the Gulf of
Guinea.
Since then some important papers upon the nagana of Togoland
have been published by Schilling and Ziemann, who carried on their
investigations in the colony itself, and by Martini, whose researches
originated in the discovery of a trypanosome pathogenic for mammals
in the blood of a pony imported from Togo into the Zoological
Gardens in Berlin.
According to Schilling ^ the disease affects horses, donkeys, and
cattle throughout the whole hinterland of Togo. Fever is inter-
mittent, and there is no definite relation between the temperature
and the number of parasites in the blood. The symptoms are not con-
stant, and the parasite is often absent on microscopical examination.
In a horse which he had under observation during the last ten
days of its life Schilling noted wasting, swelling of the testicles,
penis, joints, and belly, and a purulent discharge from the eyes and
nose ; its appetite remained good until the end. Seven days before
death its hasmoglobin was only 25 to 30 per cent. No morbid
conditions were found post-mortem. Neither in this nor in any of
the other horses did Schilling find enlargement of the spleen.
Trypanosomes may be absent from the blood and the peritoneal
cavity at the time of death, but, according to Schilling, they are
always present in the marrow of the bones. Anaemia would appear
to be due, not to a destruction of the red corpuscles in the peripheral
circulation, but to diminished production in the bone-marrow.
Schilling inoculated various animals : horses, donkeys, oxen,
goats, pigs, and dogs. They were all susceptible except the pig.
The course of the experimental disease in the horse differs from the
natural infection in that the symptoms are less marked, the swellings
being almost entirely absent.
The disease in the horse may be acute or chronic, death occurring
after an interval of from forty-three days to more than eight months.
Sudan donkeys appear more susceptible than the horse, for two of
them died in eleven and eighteen days respectively after inoculation.
In his first paper Schilling describes the evolution of the parasite
in several dogs inoculated subcutaneously or intraperitoneally. In
dogs inoculated intraperitoneally, and also in a dog in which an
abrasion on the ear was smeared with blood containing trypanosomes,
1 Schilling, Centralb.f. Bakter., I, Orig., v. 30, October 30, 1901, p. 545 ; v. 32,
April 16, 1902, p. 452, and v. 33, January, 1903, p. 184.
13
194 TRYPANOSOMES AND THE TRYPANOSOMIASES
there occurred intraperitoneal as well as intravascular multiplica-
tion of the parasite. A dog inoculated in the peritoneum with
I c.c. of horse blood containing few trypanosomes died in twenty-
eight days.
Schilling also infected a dog by allowing it to be bitten on several
occasions by a tsetse-fly which had previously fed upon a dog with
numerous trypanosomes in its blood.
Two dogs inoculated in Berlin with Schilling's trypanosome by
Stahelin/ with the object of studying the metabolism of animals
with nagana, died in twenty-four and twenty-eight days respectively.
During the course of the disease they suffered from remittent fever,
chemosis, corneal trouble, hypopyon, and wasting, and during the
last two days of life they had a subnormal temperature.
[Schilling's 2 later observations on the trypanosomiasis of Togo are
summarized by MesniF as follows : The trypanosome appears not to differ
from the type hnwei, but we have seen that Laveran and Mesnil, from their
experiments on ' cross-inoculation ' and serum-diagnosis, conclude that
this Togo disease is probably not true nagana. Schilling describes a form
of the parasite — possibly a sexual form — which is fairly wide and shorter
than the ordinary form, especially as regards the flagellum. The cyto-
plasm is pale — like the undulating membrane — and is poor in granules.]
[In the horse this disease is less acute in Togo than in South Africa.
The incubation period is 6 to 12 days ; the average duration, 50 days.
The haemoglobin may fall to 25 per cent, of the normal.]
[In the donkey the incubation period is 4 to 5 days, and the average
duration 10 to 18 days. In bovines the incubation period is 4 to 9 days,
and the symptoms are slight, the disease usually ending in recovery.]
[Berlin pigs are susceptible, but the parasite is only visible at the
beginning of the infection, and the animals recover from the infection.
Schilling had previously found that the Togo pig was refractory.]
[Most of the experiments on rodents and birds were done with a virus
passed twenty-five times through the dog. White rats died in about
28 days, but they lived considerably longer with a virus passed through
the pig (54 days) or goose (80 days). White mice died in about 37 days,
a grey mouse {M. musctilus) died in 100 days, and a M. agmrius in
122 days. Schilling thinks these long survivals are due to the passage of
the virus through dogs, for with a diyect virus he killed rats in 4 to 10 days
in Togo. The ' pedigree ' of the parasite would therefore appear to be of
considerable importance ; and the virulence of trypanosomes for the same
species of animals may vary enormously, according to the ' genealogy ' of
the parasites. This may possibly account for the fact that Schilling was
able to infect a goose, which no previous investigator had succeeded in
doing.*]
[Four animals were inoculated in Berlin and developed a mild infection,
with only febrile symptoms at the outset. These included two cows inocu-
lated (the first on three occasions) with a virus of the twenty-sixth to thirty-
first passage through dogs ; a young bull, inoculated with the blood of the
second cow ; and a calf of the first cow (born during the infection, but free
from it), inoculated when forty-five days old with the bull's blood. The
serum of these four animals did not show the bactericidal properties noted
^ Stahelin, Arch. f. Hyg., v. 50, 1904, p. ']'J.
^ [Schilling, Arb. a. d. kaiserl. Gesund., v. 21, 1904.]
3 [Mesnil, Bull. Inst. Past. 1905.]
* [These experiments, together with those on other animals, are summarized in
the table on p. 197.]
TRYPANOSOMIASIS OF TOGOLAND 195
in the Togo animals similarly treated. These microbicidal serums had
no action in vivo.]
[Passage through resistant animals did not attenuate the virus for the
dog ; but a virus of the third passage through the goose was much
attenuated for the donkey.]
Schilling has paid particular attention to the vaccination of cattle.
An ox inoculated with the virus after five passages through cattle
died in forty-one days. On the other hand, oxen or calves inoculated
with a virus which had been passed a certain number of times
through the dog or rat (three times from dog to dog in the first
experiment ; seven times alternately through dog and rat, then
exclusively through the dog up to the eighteenth and twenty-first
passage, in a second experiment) contracted a mild and temporary
infection, which rendered them immune. We have already discussed
(p. 183) the significance of these facts.
[In recent papers Schillingi gives the after-history of the 36 cattle
vaccinated by him at Sokode in 1902 (see p. 183). Seventeen were sent
into fiy areas, and of these 13 died, probably of nagana, doubtless, thinks
Schilling, because they were exposed to the fly too soon. Of the
4 survivors, i died of nagana after a fresh journey, and 3 were in perfect
health 3 years after their vaccination.]
[Of the 19 cattle kept at Sokode, 2 died fairly quickly — perhaps
from the vaccination ; 4 out of 8 tested were still infected at the end of
II months (10 c.c. blood injected into dogs).]
[At the end of 14 months 18 vaccinated cattle were taken to the
coast : 3 died (2 of nagana) and 2 others became infected, but recovered.
Three of these cattle were inoculated 2 years after their vaccination with
fairly virulent trypanosomes. A very mild infection followed, and at the
end of 3 months the blood was no longer infective in doses of 5 to 10 c.c,
while at the end of 10 months only i was infective (40 c.c. blood injected
into a dog). Schilling insists on the importance of this observation,
which seems to prove the reality of cures — contested by Koch— and
which in any case shows that ' cured ' animals are not a great source
of danger as reservoirs of infection. Schilling thinks it is advisable to
. vaccinate animals when very young.]
[A final observation of Schilling's shows how carefully one must
interpret the results of this method of vaccination, and that it is not of
much value practically. Six cattle (3 vaccinated, 3 unvaccinated) were
taken through a very bad fly belt : 5 became infected, and of these 2 died
(i vaccinated); 2 were still infected 9 months later (i vaccinated), and
I recovered quickly (unvaccinated). Of the 3 vaccinated animals, there-
fore, I died, I was still infected after 9 months, and the third did not
become infected at all.]
In igoo Ziemann^ had under observation two horses and one
dog ? which were spontaneously infected. The blood of the dog
was used to infect a goat which became ill. This goat showed
numerous trypanosomes on the eighth day, few on the eleventh, many
on the twelfth and thirteenth, few on the fourteenth and sixteenth,
and very few on the seventeenth days, after which it was rare to
find even one under the microscope, and the animal was cured.
^ [Schilling, Deui/sck. Kolonialbl., No. I, 1904; Zeitschr. f. Hyg.,v. 52, 1905,
pp. 149-160 ; abstract by Mesnil in Bull. Inst. Past., v. 4, 1906, pp.' 185, 186, from
which the above account is taken.]
2 Ziemann, Berlin klin. Wochenschr., October 6, 1902, p. 930.
13—2
ige TRYPANOSOMES AND THE TRYPANOSOMIASES
The other animals — a duck, a fowl, a pigeon, and a sucking-pig —
inoculated by Ziemann remained healthy. This last observation
confirms that of Schilling,^ but differs from the results of experiments
obtained with the Zululand virus (see p. 136). We may add that
Martini found the pig susceptible to the Togo virus.^
Martini has also inoculated his virus into a female Egyptian
buffalo and a zebra from Kilimanjaro. The buffalo died in six weeks
of typical trypanosomiasis (severe anaemia, etc.), with an enormous
number of parasites in its blood. The zebra lived for a longer time,
and, although trypanosomes were present in the blood from the
fourteenth day after inoculation, the animal remained in good health
for three and a half months. It died, however, a fortnight later,
after having shown the symptoms characteristic of nagana in the
Equidae.^
Martini* has given a very detailed account of the morphology of
his Togoland trypanosome, which appears not to differ in any
essential point from the typical T. brucei.
[Martini 5 has made an exhaustive study of the trypanosomes of two
Togo ponies which were brought to Berlin.^ The trypanosome of the
stallion was very virulent and deadly, while that of the mare was originally
only slightly virulent. Martini thought at first that the more virulent
strain was morphologically different from the less virulent one, the former
having a long flagellum, the latter a short flagellum. Later he found,
however, that the more virulent strain could have a short flagellum and
still retain its virulence. The less virulent parasite, after passage through
the horse and dog, became more virulent for a number of animals, and at
the same time the flagellum increased in length. As a rule, the short-
flagellated forms of both strains appeared more frequently in those animals
which were less susceptible to the fly disease, and which presumably had
protective bodies in their serum. This relation of length of flagellum to
virulence was, therefore, by no means constant.]
[The Trypanosome of the (J Pony. — This trypanosome killed the
original stallion in 100 to 120 days. The blood of this animal was injected
into a number of animals, with the results shown in the table on p. 197.
Martini tried especially to create a series of particular strains by repeated
passages through the same animal species. Passage through Equidee
(horse and ass) and cats did not affect the virulence much, but passage
through rats and mice resulted in the formation of a vinis-fixe, which killed
1 [We have seen, however, that SchilUng has since found Berhn pigs sus-
ceptible to his Togo virus.]
^ Martini, Arch. f. Schiffs u. Tropenhyg., v. 7, November, 1903, p. 499.
^ Martini, Deutsche med. IVoche/ischr, August 6, 1903, pp. 573-575. It should
be noted that this susceptibility of the zebra (see p. 192) to experimental inoculation
contrasts with the fact, which appears well established, that the zebra may pass
with impunity through fly areas where nagana occurs, and that its blood never
contains trypanosomes and is not infective for susceptible animals. Martini
recognises that further investigations are necessary upon this point — for example,,
upon animals living for a long time in fly areas and made to do work.
^ Martini, Zeitschr.f. Hyg.,v. 42, 1903, p. 341, and Koch's 'Festschrift,' Jena,
1903, p. 219.
^ [IVIartini, Zeitschr.f. Hyg. u. Infec, v. 50, 1905, pp. 1-96 ; abstract by Mesnil,
Bull. Inst. Past.,\. 3, 1905, pp. 463-466.]
" [Practically the whole of the following 14 pages, down to the end of Section 8,
has been added. — Ed.]
TRYPANOSOMIASIS OF TOGOLAND
197
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214 TRYPANOSOMES AND THE TRYPANOSOMIASES
Probably mal de la Zusfana is prevalent in many other parts of Algeria, but
its distribution, the mode of transmission, and the animal constituting the
reservoir of the virus, all require further investigation. Tsetse-flies do not
occur in Algeria, so that this is not true nagana or one of the nagana-like
diseases propagated by Glossina; but until more is known of the disease
and its trypanosome, it is better not to use the name North African surra.]
Trypanosomiasis of Dromedaries or El Debab.^ — In October,
1903, the Sergents detected the presence of trypanosomes in the
blood of several dromedaries at Oued-Athm6nia, department of
Constantine. In a herd of twenty animals three were found infected,
of which two were thought to be ill by the camel- drivers. One of
them, an old female, had aborted each time she had become
pregnant. She had been ill for two years, but, except for marked
wasting, there was no obvious sign of disease — no ulceration of the
vulva or anus, nothing in the belly, eyes, or lips. The mouth
temperature was 38'9° C. [102° F.]. As many as three parasites
were seen in a field with the immersion lens. The third animal was
a camel six months old, which showed no sign of disease. There
were two or three parasites in each preparation of its blood. It
seems, then, that the only symptom is progressive wasting, which
ends in death.
The morphology of this trypanosome resembles that of the
parasites of nagana and surra, and, moreover, presents no charac-
teristic differences. [The Sergents state, however, in a later paper^
that the avferage size of their trypanosome is ig /x long by i"5 /^ broad,
the average length of the nagana and surra parasites being 25 /a.]
The centrosome stains well, and division forms are seen in the
peripheral blood. The Sergents inoculated the trypanosome from
the blood of the old camel into different laboratory animals. They
also made series of passages through rats and mice, by which the
virus became altered in virulence.
From the outset white rats were consistently susceptible to the
trypanosome. The disease lasted on an average sixteen days after
subcutaneous inoculation, and nine and a half days after intra-
peritoneal inoculation. The incubation period was respectively
three days and one day. Three or four days after their appearance
in the blood of the rats the parasites diminished in number or
disappeared completely for some days, then reappeared and were
constantly present. When death occurred, the trypanosomes had
either become very numerous or they diminished in number during
the last few days of the animal's life.
1 That is the name which the Sergents suggest. In publications of the period
1850-1860, particularly in Vallon's paper upon the dromedary, this disease of
dromedaries, which at that time formed the subject of several works, was thus
designated. El debab means the fly, or horse-fly. According to information
obtained from the Arabs by the Sergents, the disease is contracted in the Tell,
where the horse-flies occur, during the short period of summer (forty days only).
See in this connection Railliet, Zool. mMic. et agricole, p. 793.
2 [Ed. and Et. Sergent, Ann. Inst. Past., v. 19, 1905, pp. 17-48].
TRYPANOSOMIASES OF ALGERIA 215
At the autopsy the only lesion noted was an enormous hypertrophy
of the spleen, which in some cases weighed ten times as much as the
normal.
Sewer rats reacted as a rule in the same way as white rats, but
some of them lived for a longer time. Thus, the Sergents had a
sewer rat which lived for live and a half months after inoculation.
It showed trypanosomes in its blood at first nearly every day, then
at fairly long intervals, and continued to do so until it died.
White mice seem to be a little less susceptible than white rats.
Some of them died in twelve days with the parasites swarming in
the blood, but in others the disease was more prolonged, and on
some days the parasites were absent from the peripheral blood. The
average duration of the incubation period was four days after subcu-
taneous inoculation, and two days after intraperitoneal inoculation.
At the autopsy there was very considerable enlargement of the spleen.
Grey mice reacted very irregularly, some of them not becoming
infected after inoculation with virulent blood. Others developed
a mild infection, which was only temporary, and these animals
appear to have recovered.
By repeated passages through rats and mice, the virulence, which
at first varied somewhat for diiferent animals of the same species
(particularly mice), became more constant and at the same time
more exalted. Inoculations with such an exalted virus produce a
form of the disease which progresses, with constant increase in the
number of parasites in the blood.
[In later experiments it was found that this debab virus, which
at first killed mice in about twelve days, became less virulent for mice
after being passed through rats for two years. Thus, five white mice,
after injection with rat's blood, developed only a slight infection,
from which they recovered cured, but not permanently immunized.
That they were cured is shown by the fact that the blood and
extracts of the organs of two of them — killed one year after inocula-
tion — did not infect rats. Two others of these cured mice were not
immune, but were much more resistant than control mice. The
latter died in seven to eighteen days, the two former in fifty-four and
sixty-one days.]
Rabbits reacted to inoculation with this trypanosome, as they do
with the other pathogenic mammalian trypanosomes. The disease
followed an irregular course ; the trypanosomes increased from time
to time in the blood, the increase coinciding sometimes, but not
always,' with a rise of temperature. There were also oedema of the
genital organs and anus, loss of hair about the tail and the base
of the ears, and purulent conjunctivitis. In three rabbits the
average duration of the disease was nineteen days, but other rabbits
survived fifty days.^ After subcutaneous, intraperitoneal, and intra-
' [One hundred and fifty days is the maximum given in a later publication of the
Sergents.]
2i6 TRYPANOSOMES AND THE TRYPANOSOMIASES
venous inoculation, the incubation period was eight and a half da}'s,
six days, and two days respectively.
In guinea-pigs the shortest duration of the disease was twelve days,
but some lived for more than four months, two guinea-pigs, still alive,
having been infected for four and a half and seven and a half months.
[One guinea-pig ( ? ) lived eleven months after inoculation.^ She gave
birth to two uninfected young ones, which were found to be normally
susceptible to the virus.] The incubation period was, on several
occasions, only three days after subcutaneous inoculation, but was
sometimes much longer. After intraperitoneal inoculation it was
about four and a half days. The parasites were, as a rule, numerous
in the blood of the guinea-pig, and the animal sometimes lived in that
condition for several weeks. The external lesions so characteristic in
the rabbit were not seen in the guinea-pig.
In the dog the course of the disease was rather irregular, the
appearance of the parasites in the peripheral circulation coinciding
with the rises in temperature. In a dog which died thirty days after
inoculation the parasites swarmed in the blood towards the end
of the animal's life, and this was accompanied by a marked fall
of temperature. The other dogs, which died in thirty-five and
thirty-seven days, did not have a subnormal temperature.
A Macacus died two months and eight days after subcutaneous
inoculation. The parasites were fairly numerous from the fourth to
the seventh day, when the monkey had a subnormal temperature.
The trypanosomes then disappeared from the blood, and became fairly
numerous again from the fifteenth to the seventeenth day; but from
that time they were very scanty or even absent on microscopical
examination, particularly during the last month. As a rule, the
monkey's temperature was subnormal, and the presence of trypano-
somes definitely concided with the rises of temperature above 37° C.
[g8"6° F.]. The monkey died with a subnormal temperature, after
having slept for two or three days.^ On the last day the temperature
was below 25° C. [77° F.], yet trypanosomes were present.
A goat weighing 34 kilogrammes became infected after subcu-
taneous inoculation with the blood of a rat. At the end of five days
trypanosomes were seen on microscopical examination, and subse-
quently they were only seen again, and then only in very small
numbers, from the tenth to the fourteenth day. After that time
microscopical examination was always negative ; but rats inoculated
with 5 c.c. of the goat's blood one month and two months after the
inoculation of the goat very rapidly became infected. The goat,
which appeared on the road to recovery, died very suddenly three
months after inoculation. During the progress of the disease its
weight had fallen to 21 kilogrammes, but at death it had risen again
to 27J kilogrammes.
1 [This is the maximum duration given in a later pubhcation of the Sergents.]
2 [In the Sergents' paper, An;z. Inst. Past., v. 19, 1905, it is stated that the
monkey slept for ^. fortnight before death.]
TRYPANOSOMIASES OF ALGERIA 217
Lastly, the Sergents inoculated a horse, which died in three and
a half months. It had intermittent fever, with rises of temperature
to about 40° C. from the eighth to the eleventh day and from the
sixteenth to the eighteenth day, and to between 40° and 41° C.
[104° to 105-8° F.] from the twenty-third to the twenty-sixth day,
from the thirty-fourth to the thirty-eighth, forty-fifth to forty-eighth
day, and on the sixty-sixth, seventy-seventh, and ninety-fifth days.
In the intervals the temperature was generally normal. These
rises of temperature coincided with increases in the number of
parasites in the blood, which were, as a rule, only visible in films
during these febrile attacks. During several of the paroxysms they
were numerous in the blood ; they were scanty or absent during the
few days before death. The course of the disease closely resembled
that of surra.'
At the end of a week the horse had a patch of oedema the size
of a hand in the abdominal wall, and also oedema of the sheath.
This oedema spread in the form of a longitudinal band, occupying
the whole ventral region. During the course of the second month
the horse passed dark brown or reddish urine, but neither red
corpuscles nor haemoglobin could be detected in it. The horse died
in a wasted condition.
[Several bats (Myotis murinus) were inoculated by the Sergents
intraperitoneally, but they died in six days without becoming in-
fected. Nicolle succeeded, however, in infecting bats {Vespertilio
tuhli) with this trypanosome. The infection was a mild one, and
the bats recovered from it (see p. no).]
This trypanosomiasis of dromedaries does not appear to be
dourine. The pathogenicity of its trypanosome for the goat and
monkey,^ and the fact that the young camel which had never had
connection became infected, make this diagnosis improbable. More-
over, the characteristics of the disease experimentally produced in the
horse differ markedly from the normal course of dourine. In the
former disease (i) the febrile paroxysms are not restricted to the
onset of the disease; and (2) trypanosomes are often present, and
even numerous, on microscopical examination, which is never the
case in dourine.
The trypanosome of the Sergents is evidently different from that
of caderas, since its centrosome is easily visible.
What is the relation of this trypanosomiasis of dromedaries to
nagana and surra ? This is a question requiring further study for
its elucidation. It is particularly important to compare this disease
with the trypanosomiasis of dromedaries in Timbuctoo. The disease
attacks the same animals, and the natives call it by the same Arabic
name (el debab) in the two districts. The disease is spread most
^ [This argument no longer holds good, since Mesnil and Rouget have shown
that monkeys and goats are susceptible to the virus of dourine ; nevertheless, the
observations of the Sergents recorded later prove almost conclusively that debab
and dourine are different diseases.]
2i8 TRYPANOSOMES AND THE TRYPANOSOMIASES
probably by means of these debab, which are similar, if not identical,
flies (horse-flies).
These are the only two African diseases in which insects other
than the tsetse are incriminated.^ Finally, if intercourse by means of
caravans between Timbuctoo and Twat is not frequent, it none the
less exists, and it is quite likely that the Algerian and Sudanese
diseases in question may have a common origin.
[The recent observations of the Sergents^ have materially increased
our knowledge of these Algerian trypanosomiases. In addition to dourine,
there are two diseases — (i) the well-defined disease of dromedaries, called
debab; and (2) the isolated cases or limited epizootics amongst horses
called by Rennes mal de la Zusfana. The natives in various parts of
Algeria have long recognised these diseases of camels and horses, which
they say are occasioned by the bites of horse-flies. The horses in
Constantine are said to become infected in the spring — when these flies
are very prevalent — and never to survive the succeeding winter. The
symptoms usually appear with the cold season. There is marked dragging
of the legs, but wasting and loss of appetite and strength are absent. In
the Oran animals, which become infected in the Tell district (see footnote,
p. 214), the symptoms are more marked. They include loss of appetite,
fatigue, wasting, hanging of the head, staring of the coat with partial
loss of hair, and oedemas ; there is no marked weakness of the hind-
quarters or limbs. The disease is always fatal in horses, and lasts a
shorter time than debab does in dromedaries.]
[The examination of the blood of animals from various parts of Algeria
shows that the disease in dromedaries is very widely distributed. Of
352 dromedaries examined during 1904 and 1905, 33 (9*4 per cent.) were
found to be infected, whereas of 594 Equidse examined during the same
period only i (o'ly per cent.) was found infected.]
[Big game cannot be the reservoir of the virus in Algeria ; therefore it
is probably the dromedaries which serve as the source of infection for
camels and horses. The occurrence of these small epizootics among the
horses of the Spahees is explained by the occupation of oases by cavalry,
and by the habits of the Tabanidae, which prick several horses — sufficiently
to inoculate them with the virus — before finally settling on one to feed.]
[The Sergents think that the two diseases, as observed in dromedaries
and in horses, are probably identical. Taker and tmerdjin are two local
names for the horse disease, but these should be merged into debab if
certain cross-inoculation experiments still in progress show that the
diseases are identical.]
[The Experimental Study of the Viruses. — The tahev virus killed
white vats in six to forty days, and a rabbit in five months. Guinea-pigs were
easily infected, but showed no lesions. In a sheep no trypanosomes were
found, but the blood was still infectious for rats on the thirty-third day.]
[Oran debab killed white rats in sixteen to seventy-five days, and white
mice in seven to thirty days. Guinea-pigs and sheep reacted as with the
taher virus.]
[Constantine debab, which was the virus used by the Sergents in the
experiments already recorded (see pp. 214-217), was passed through rats
for a year, then inoculated into a goat, in which it was found ten months
later, and afterwards again passed through rats. Two sheep were still
infected a year after inoculation, and two goats ten months after
inoculation.]
1 [We have seen, however, in various parts of this chapter, that several other
trypanosomiases, resembling nagana, have been described in districts where the
tsetse-fly has not been found.]
^ [Ed. and Et. Sergent, Ann. Inst. Past., v. 20, August, 1906.]
TRYPANOSOMIASES OF THE FRENCH SUDAN 219
[Infection Experiments. — Tabanidae seem to be the carriers of the
infection. Two species — Atyloius [Tabanus) nemoralis (Meigen) and At.
(Tab.) tomentosus (Macquart) — are specially incriminated. The Sergents
were able to convey the disease to healthy animals by a single prick,
without suction of blood, of a sittgle fly. These' positive results were obtained
when there was no interval between the pricking of the diseased animal
and that of the healthy animal, and in one case after an interval of twenty-
two hours. Motile trypanosomes were never found in the stomach of
Tabanidffi one hour after a feed. Stomoxys a.nd Hcematobia are never found
on camels, and are consequently of no importance in the propagation of
the disease.]
[Similar experiments with the same species of Tabanidae gave positive
results with the trypanosomes of nagana (five out of nine positive), mal
de la Zusfana (one out of six), and dourine (two out of two). These
positive results were all obtained when the pricking of the infected and
of the healthy animal took place without an interval. All the other ex-
periments were negative.]
. [Experiments with young ticks, hatched from eggs laid by a mother
living on heavily infected animals, were negative. Inoculation experi-
ments by way of intact mucous membranes (conjunctival and genital —
rnale and female) gave positive results with dourine in four cases out of
eight. Similar experiments with debab (six in number) were all negative.]
Section 10.— Trypanosomiases of the French Sudan. ^
Trypanosomiasis of Dromedaries or Mbori. — Early in the
year 1903 the military veterinary officer Cazalbou was commissioned
to investigate the disease of the dromedary known as mbori, or the
fly disease, which causes the death of most of the camels coming
from the Sahara to the Sudan.
Cazalbou, at Timbuctoo, examined seventeen dromedaries which
were said to be infected. The animals were wasted, and sixteen of
them showed trypanosomes in the blood.
The sick animals have rises of temperature to about 40'5° C.
[105° F.], and it is when the temperature is high that the trypano-
somes are most numerous in the blood. Fever and wasting are the
only constant symptoms of the disease. There is no oedema,
swelling of the limbs, or paralysis. Frequently there is a copious
watery discharge from the eyes, and sometimes diarrhoea is present.
The disease usually ends fatally after an average duration of
five to six months. Animals which recover are immune.
Cazalbou took to Segou two dogs and two sheep which had been
inoculated at Timbuctoo with the blood of camels suffering from
mbori. He was thus able to study the course of the disease in
different species of animals. A dog which was brought to Paris
enabled one of us to corroborate and to complete Cazalbou's
experiments.
"• [A. Laveran, 'Reports to the Acaddmie de Mddecine,' June 30, 1903, and
April 26, 1904. [L. Cazalbou, Rec. de mid. vdtdr., v. 81, October 15, 1904, p. 615 ;
C. R. Soc. Biol., V. 58, April i, 1905, pp. 564, 565 ; Revue gdn. mid. vit., v. 8, 1906,
pp. 240-248. P^caud, C. R. Hoc. Biol., v. 60, 1906, pp. 58, 59.]
220 TRYPANOSOMES AND THE TRYPANOSOMIASES
The results of the researches upon this trypanosome may be
summarized as follows :
Rats and Mice. — In the grey rats of the Sudan which were
inoculated by Cazalbou, subcutaneously or intraperitoneally, with
blood rich in trypanosomes the parasites appeared in the blood on
the second or third day, and gradually increased in number until
death, which occurred on the eighth or ninth day. In white rats in
Paris the parasites appeared in the blood on the third or fourth day,
and became increasingly numerous until death, which occurred from
the thirteenth to the sixteenth day. The spleen was greatly en-
larged, weighing 2-2 to 3 grammes in rats of 165 to 190 grammes.
In the grey mice (? species) of the Sudan the trypanosomes
appeared from the third to the sixth day after inoculation. At first
they were numerous in the blood on several occasions, but later on
they were present only in small numbers and at longer or shorter
intervals. Of four mice inoculated at Segou, two died 115 and 141
days after inoculation ; the other two were still alive 138 and 148
days after inoculation.
Two wild grey mice in Paris died in eight and nine days. Three
white mice (Paris) died in seven, fourteen, and twenty-four days.
Trypanosomes appeared in the blood two to three days after inocula-
tion, and steadily increased in number until death occurred.
In the ' giant rat ' of the Sudan the parasites appeared on the
seventh day, and increased in number until the eleventh to
the thirteenth day, when death occurred. Adult rats were more
resistant than young rats.
Guinea-pigs and Rabbits. — Of four guinea-pigs inoculated in
Paris only one showed many parasites in its blood ; in the other
three the parasites were always scanty. Three of these animals
died in twenty-seven, twenty-eight, and forty days ; the fourth was
still alive two months after inoculation, [but died on the T26th
day with numerous trypanosomes in its blood]. ^ Post-mortem
the spleen was only slightly, if at all, enlarged ; [but in the animal
which survived 126 days the spleen weighed 3 grammes, the total
body-weight being 500 grammes].^ Two rabbits inoculated — the one
intraperitoneally, the other subcutaneously — became infected. One
month later the trypanosomes were very scanty in the blood, and
one of the rabbits was very thin and was suffering from double
blepharo - conjunctivitis. Of these two rabbits, one died on the
fifty-first day of the disease ; the other was still alive two months
after inoculation, but the trypanosomes were extremely scanty in its
blood. [This rabbit died ninety-six days after inoculation ; its
weight was 1,360 grammes, that of the spleen being i gramme] .'■
Dogs. — Four Sudanese dogs died thirty, forty-eight, fifty-six, and
seventy-five days after inoculation. The dog in which the virus was
brought from the Sudan to France died in sixty-five days. Of two
^ [Information kindly furnished by the authors.]
TRYPANOSOMIASES OF THE FRENCH SUDAN 22T
dogs inoculated in Paris, one died in twelve and the other in
seventeen days after inoculation, with many parasites in their
blood. The chief symptoms of the disease in the Sudanese
dogs were febrile paroxysms, coinciding with increases in the
number of the parasites, wasting, and swelling of the inter-
maxillary space and throat (in three out of four cases). Post-
mortem there was serous infiltration of the connective tissue of
the intermaxillary space and throat with enlargement of the cervical
lymphatic glands. The spleen was much enlarged in two out of
four cases. In the Sudanese dog which was brought to France the
spleen weighed 160 grammes (weight of dog 8,300 grammes) ; in the
dog weighing gj kilogrammes, which died in twelve days, the spleen
weighed 60 grammes.
Cats. — A kitten four months old inoculated by Cazalbou on
July 24, 1903, showed the trypanosome in its blood on the seventh
day and afterwards only at intervals. On January i, 1904, 161 days
after inoculation, the cat was still alive.
[Panisset,^ at Alfort, inoculated a cat with the trypanosome
of mbori ; the cat died in four months. Mbori took considerably
longer to kill cats than did the Mauritian surra].
Sheep and Goats. — Two rams inoculated at Timbuctoo with
the blood of a dromedary died in twenty and twenty-one days, but
it is not certain that they succumbed to the trypanosomiasis. A
ram inoculated on May 20, 1903, had a series of febrile paroxysms,
the temperature going up to 40'3° to 40"9° C. [i04'6° to 105-5° F.].
Seventy days after inoculation this animal's blood was still infectious
for rats, but 100 days after it was no longer so, and the ram must be
regarded as having recovered from the disease.
A nanny goat injected on August 6, 1903, was still infected on
November 10 (ninety-seventh day). The chief symptoms were rises
of temperature and enlargement of the pharyngeal lymphatic glands.
Trypanosomes were never found on microscopical examination of the
blood, and it was always necessary to inject rats in order to show
the presence of the infection. The after-history of the disease in this
goat is unknown.
A sheep and a hilly goat inoculated in Paris became infected. The
trypanosomes were very scanty in the blood of these animals, which
never had any rise of temperature.
[The sheep died six and a half months after inoculation. The
goat was cured eleven months after inoculation, and had then
acquired immunity against mbori, for on reinoculation with the
virus of mbori the animal did not become reinfected.^ Two months
after being unsuccessfully reinoculated with mbori, the goat was
subcutaneously inoculated by Laveran with the Mauritian surra
trypanosome (see Chapter VIII.). There was a marked febrile
reaction — for a fortnight the temperature was about 40° C. [104° F.],
1 [Panisset, C. R. Soc. Biol., v. 58, 1905, p. 16.]
2 [Laveran, C. R. Acad. Sciences, v. 141, December' 26, 1905, p. 1204.]
222 TRYPANOSOMES AND THE TRYPANOSOMIASES
and on three occasions reached 40-8° C. [los's" F.]. The blood,
however, never showed trypanosomes, nor did any of the test animals
inoculated ever become infected. Thus, the goat which had acquired
immunity against mbori was also immune against Mauritian surra.
This result confirms those of Valine and Panisset,^ who had pre-
viously shown that bovines which were immunized against surra were
likewise immune against mbori.]
Roebucks {Sudanese). — -An inoculated roebuck showed very many
trypanosomes in its blood on several occasions. On the 183rd day
after inoculation it was still in excellent condition. Another roe-
buck inoculated simultaneously with the preceding died rapidly with
nervous symptoms — inco-ordination of movements and convulsions.
Trypanosomes were numerous in its blood.
Horses. — Three horses were inoculated by Cazalbou — two in
the jugular vein and the third subcutaneously. All three became
infected, trypanosomes appearing in the blood about the fifth day.
They multiplied in the blood irregularly, the exacerbations usually
coinciding with the febrile paroxysms.
Apart from fever, the chief symptoms observed were wasting,
oedema of the scrotum and sheath, swelling of the fetlocks, profuse
sweating, epiphora, and conjunctival hsemorrhages. At a later stage
of the illness there was an abundant papular eruption, especially on
the head, neck and shoulders, back, and hind-quarters. The lesions
were covered with scabs, which, on falling off, left small round,
superficial sores. One of these horses died 136 days after inocula-
tion ; the other two were lost sight of on the 144th and 184th days of
the disease.
[A horse inoculated with mbori at Alfort was alive six months
later, and its blood was still infectious for test animals. The average
duration of surra in the horse is one to two months, so that the
trypanosome of mbori is distinctly less virulent than that of Indian
and Mauritian surra.]
Pathogenic Agent. — The trypanosome of mbori measures 20 /i
to 25 /i long, by i"5 /* to 2 juwide at its middle. Usually it is slender,
and resembles T. evansi more than T. brucei. The centrosome is
about as large as in these two trypanosomes, and there is no
characteristic feature by which this trypanosome can be differentiated
from them.
Human serum and trypanred have a marked effect upon the
trypanosome of mbori, causing it to disappear, either temporarily or
even permanently, from the blood of inoculated mice and rats.
[Laveran has found that mice infected with mbori are rapidly
cured by one injection of trypanred. Rats were also sometimes
cured by one or two injections of this dye, and in all cases com-
bined treatment with trypanred and arsenious acid gave excellent
results in these animals. Mice and rats infected with surra were
^ [ValMe and Panisset, C. R. Acad. Science, v. 139, November 21, 1904, p. 901.]
TRYPANOSOMIASES OF THE FRENCH SUDAN 223
more difficult to cure in this way. In mice the injections of
trypanred had to be repeated or the combined treatment used ;
with rats the latter method had always to be employed, or there were
many failures.]
Mode of Propagation. — There seems to be no tsetse in the
neighbourhood of Timbuctoo, but the natives agree in saying that
mbori is propagated by means of a fly called debab, which is a Tabanus.
To sum up, mbori is not sharply differentiated from nagana (in
Paris dogs died in twelve days), surra, or the trypanosomiasis of
dromedaries in Algeria.
Many of the symptoms of mbori occur also in nagana or in
surra : irregular- rises of temperature, oedema of the scrotum and
sheath in horses, ecchymoses in the mucous membranes, especially
the conjunctiva (which is frequently seen in surra, as in mbori), and
hypertrophy of the spleen.
Other symptoms seem special to mbori : swelling of the inter-
maxillary space and throat in dogs, enlarged cervical glands in
several species of animals, and in the horse a papular eruption
similar to that seen in caderas.
[Cazalbou's original belief that mbori is a distinct morbid entity
has been disproved by the experiments of Laveran and of Vallee and
Panisset. From these experiments it may be concluded that the
trypanosomes of surra and mbori are the same species. The
trypanosome of mbori is merely a variety of T. evansi, a little less
virulent than the trypanosome which produced the serious epizootic
in Mauritius. Laveran remarks : ' This is the first time that Indian
surra has been recognised on the continent of Africa, a grave epizootic
having previously been observed (1902-1904) in the island of
Mauritius. It is possible that other African epizootics recently
described as due to trypanosomes other than T. brucei may likewise
be varieties of surra.'] ^
Trypanosomiasis of Cattle or Soumaya. — Cazalbou describes
under the name sownaya or souma, borrowed from the dialect of the
Bambaras, a trypanosomiasis which periodically attacks cattle in
the French Sudan and kills a large number of them. In 1903 this
epizootic appears to have started in the humped cattle (zebus) of
Macina, which arrived at Segou suffering from the disease. The
Macina district, which is a cattle-rearing centre situated higher
up the river and to the south-west of Timbuctoo, is periodically
inundated by the Niger. It is in November, when the herds of
cattle are brought into the areas which are becoming dry, that the
epizootic usually breaks out. From this centre it spreads to the
neighbouring districts, to Guinea, and as far as the Ivory Coast and
1 [See Laveran's remarks upon Valine and Panisset's communication in
C. R. Acad. Sciences, v. 139, p. 901.]
224 TRYPANOSOMES AND THE TRYPANOSOMIASES
Dahomey, the spread being favoured by the considerable export of
cattle from Macina which takes place.
From January to July, 1903, of 4,694 head of cattle taken to
Segou 676 died, the mortality being at its maximum in June (155
per 1,000). If, as is probable, infection occurred in November, the
average duration of the disease in the animals which succumbed was
seven to eight months.
The two races of cattle in the Sudan — those with humps (zebus),
and those without humps — as well as their cross-breeds, are attacked
by soumaya.
[Pecaud^ has also observed this epizootic in the neighbourhood
of Bamako, the new capital of Haut-Senegal and Niger, and of
Kati. It affects oxen, Algerian mules, native horses, and asses.
The mortality amongst oxen is about 20 per cent. In horses there
is fever and oedema of the legs, rarely oedema of the abdominal
walls. Death occurs in about fifty days in horses, but in the mule
the disease is more chronic, and recovery is more frequent than in
the horse.]
[The disease begins in July — the middle of the rainy season — and
lasts until January. Pecaud remarks that this seems to be a special
trypanosomiasis propagated by the oxen of Macina.]
[Cazalbou^ saw the disease in horses in the region of the River
Bani. These horses developed the trypanosomiasis after being
taken to the river banks, where they were bitten by tsetse and many
Tabanidas.]
In cattle the onset of the disease is insidious, but about the third
month there is a certain degree of wasting, which gradually becomes
more pronounced. The skin becomes harsh and the coat stares ;
there is a watery discharge from the eyes, and occasionally slight
diarrhoea is present. In the zebu, which always has a well-developed
dewlap, there is often oedema in that region, sometimes extending to
the lower part of the thorax. In the cattle without humps oedema
is rare. In the later stages of the disease emaciation is extreme,
and at the same time the gait becomes slow and heavy ; the hair is
thin, and is easily pulled out ; there is marked anaemia, digestion is
impaired, and diarrhoea is often present.
During the course of the disease there are irregular rises of
temperature, the fluctuations being often very considerable [from
96° to io6'8° F.] ; death occurs with hyperpyrexia.
The duration of the disease is from four to twelve months, the
average being seven to eight months.
Besides the emaciation, there is no constant lesion found post-
mortem, the spleen being very rarely enlarged.
The trypanosomes are always scanty in the blood ; they very
closely resemble the parasite of mbori.^
1 [Pecaud, C. R. Soc. Biol., v. 60, 1906, pp. 58, 59.]
2 [Cazalbou, Rec. de mid. veter.., v. 81, October 15, 1904.]
^ [Details of morphology are given later.]
TRYPANOSOMIASES OF THE FRENCH SUDAN 225
Cazalbou thinks that soumaya is propagated by a large Tabanns,
which is very common in French Sudan in wet districts, along the
borders of ponds and the banks of the rivers. [Pecaud is also of
opinion that the disease is propagated by horse-flies (Tabanus), and
not by tsetses. Bouffard^ has recently succeeded in transmitting
the disease experimentally from an infected to a healthy calf by the
bites of Stomoxys. He states that large numbers of flies were caught
around the different stations in this district, where the mortality
amongst horses and oxen was very great. These flies were mainly
Stomoxys and Hippohosca ; not a single Tabanus or tsetse-fly was
among them.]
Cazalbou made experiments on different animals in order to study
the pathogenic effects of the trypanosome of soumaya. Three grey
rats died in 27, 30, and 58 days. Mice died in 4 to 7 months after
inoculation. The cat and the Sudanese dog^ appear to be refractory.
[Laveran,^ who has studied this disease and its pathogenic try-
panosome in a sheep inoculated by Cazalbou at Segou with the
blood of a naturally infected horse, and taken to Paris in April, igo6,
has come to the conclusion that the trypanosome of souma (or
soumaya) is a new species, which he calls T. cazalboui.~\
[Morphology. — The length of this trypanosome, including free
flagellum, is about 21 ^; its width i"5 /x. The nucleus is oval, and is
situated about the middle of the body. The centrosome is distinct,
round in shape, and close to the posterior end of the body, which is
rounded off. There are fine chromatic granules in the cytoplasm.
The undulating membrane is poorly developed, and shows few folds,
like 7\ lewisi. It is bordered by the flagellum, which becomes free
at the anterior end. Division of the trypanosome is by binary
fission, and usually starts in the centrosome.]
[In its pathogenic effects upon different species of animals,.
T. cazalboui differs markedly from allied species of trypanosomes.
The natural infection occurs in Equidas and Bovidse. Small
ruminants (sheep, goats, antelopes) are very susceptible, but rodents
(rats, mice, guinea-pigs), monkeys, and dogs are, as a rule, refractory.
P6caud also found the dog refractory.]
[In the goat and sheep the incubation period is about ten days.
The principal symptoms are fever (the temperature rose to 413° C.
[io6"4° F.] in one case), wasting, and general weakness. In the two
goats inoculated by Laveran kerato-conjunctivitis occurred at an
early stage of the infection. Trypanosomes were often found in
blood-films, which is not the case in other trypanosome infections in
these animals.]
^ [G. Bouffard, C. R. Soc. Biol., v. 62, 1907, p. 71.]
^ [Cazalbou originally said that dogs were susceptible and died in three ta
five months (see Laveran and Mesnil, Orig., p. 198), but in a letter to Laveran,
dated January 5, igo6, Cazalbou states that dogs inoculated with souma did not
become infected. In his earlier experiments he was evidently dealing with another
trypanosome.]
5 [Laveran, C. R. Acad. Scietices, v. 143, July, 1906, p. 94.]
15
226 TRYPANOSOMES AND THE TRYPANOSOMIASES
[Cross-inoculation experiments show that souma is distinct from
surra and mbori.]
[The Macina appears to be the principal focus of souma in the
French Sudan, but Pecaud has also observed it at Bamako and
Kati, in the district of Moyen-Niger, The same disease has been
described by G. Martin in French Guinea (see next section), and
possibly the trypanosomiasis of cattle in Erythrea (Memmo) and
that of cattle in Uganda (see p. 205), are due to this trypanosome.]
[In addition to mbori and souma, there appears to be a third
trypanosomiasis in the Haut-Niger district (French Sudan), for in
one of the inoculated sheep brought to Paris by Cazalbou, Laveran
found a trypanosome closely resembling that of the Gambian horse
disease, T. dimorphony]
[In a recent paper ^ Laveran states that it is probably a new species
of trypanosome, for which he proposes the name T.pecaudi. A sheep
which recovered from the infection and proved refractory on reinocu-
lation subsequently developed a typical infection with T. dimorphon.
From this Laveran concludes that T. pecmidi and T. dimorphon are
distinct species.]
[As in the case of T. dimorphon, two forms of the parasite occur in the
blood of infected animals : (i) Long, slender parasites, 25 /n to 35 /"• long,
by about i'5 /a wide. Posterior end more or less pointed; undulating
membrane very narrow ; free flagellum fairly long ; nucleus elongated.
(2) Short, broad forms, 14 /i to 20 /x long, by 3 /i or even 4 fj, wide.
Posterior end very blunt ; undulating membrane very wide and with few
folds ; no free flagellum ; nucleus rounded. All the inoculated animals
showed both forms, and intermediate stages were rarely seen.]
[Human trypanosomiasis is rare in the Haut-Niger district, but
is endemic in several other parts of the French Sudan.]
Section 11. — The Trypanosomiases of French Guinea.
[In 1904 Laveran^ found trypanosomes in blood-films taken
from two sick horses at Conakry, in French Guinea, by Dr. Tautain.
One horse belonged to the station of Telemele, in Fouta-Djalon, the
other to that of Toumanea, on the boundary between Fouta-Djalon
and the Sudan. The latter horse was taken from Touman6a to
Sanguiana (in Balaya), where it remained a month, and where it
was bitten by flies called sigui tegue. On its return to Toumanda it
began to waste. The wasting increased ; there was extensive oedema
of the abdominal walls, and later of the hind-limbs ; fever was almost
continuous at this time, but for a fortnight before death, which
occurred about three months after the horse Was brought back to
1 [In his article in the Jiec. de niM. vetdr. Cazalbou states that true nagana
occurs along the banks of the River Bani, and another trypanosomiasis — baleri — in
the Haute-Volta district.]
2 [Laveran, C. R. Acad. Sciences, v. 144, 1907, p. 243.]
^ [Laveran, C. R. Soc. Biol., February 27, 1964 ; C. R. Acad. Sciences, v. 139,
1904, p. 658, and V. 140, 1905, p. 75.]
TRYPANOSOMIASES OF FRENCH GUINEA 227
Toumanea, the temperature was generally subnormal. Towards the
end of the illness weakness and wasting were extreme ; .there were
no eye lesions.]
[Post-mortem the spleen and liver were enlarged and friable ;
small ecchymoses were present under the serous membranes, and
there was gelatinous substance about the heart.]
[The trypanosomes found in the blood of these two horses
were short (about, 14 /^ in length), and morphologically resembled
T. dimorphon/]
[This observation of Laveran proves that in French Guinea an
equine trypanosomiasis exists, as well as the human disease which is
endemic in the greater part of Upper Guinea. But it is to the very
thorough investigations of G. Martin ^ that we are indebted for our
present knowledge of the various trypanosomiases of French Guinea.
Martin found numerous trypanosomiases existing in Lower Guinea,
in the mountainous districts of Fouta-Djalon and of Lab6, and along
the banks of the Niger and of the Rio-Nunez. [These diseases
are present throughout Upper and Lower Guinea in endemic form,
and epidemics frequently arise in which the mortality is from 30 to
40 per cent.]
[These diseases were acute or chronic, and natural infections
were met with in the horse, ass, mule, ox, sheep, goat, dog, and pig.
There appear to be at least two animal trypanosomiases in French
Guinea : ' the one, the more important, caused by T. dimorphon,
which was found, not only in the blood of Equidae and of Bovidee,
but very probably also in that of sheep, dogs, and pigs ; the other
particularly prevalent in the region of the Niger, and affecting Equidae
and Bovidas imported from Beledougou and Macina, which is due to
r. cazalboui' (Martin). The trypanosome of the goat disease also
resembled that of souma {T. cazalboui).~\
[The more important of these trypanosomes, the T. dimorphon, examined
fresh, showed parasites of various sizes, some very active, but the
majority only slightly motile, and not travelHng out of the field of the
microscope. The undulating membrane is feebly developed. The trypano-
somes, when numerous in the blood of a rat or mouse, show a marked
tendency to agglutinate as soon as the film is made. In stained speci-
mens, too, many paired forms are visible, the joined ends overlapping to
some extent, so that the centrosomes come to lie side by side. The
trypanosomes measure 13 yu. to 15 /x, 20 /x to 23 /x, and some even 27 /u, to
28 ,..]
[In stained films of the blood of animals inoculated with trypanosomes
from different sources, Martin was unable to see, as were Laveran and
Mesnil, and Thomas and Breinl (see next chapter), the long free flagellum
described by Button and Todd. Even in the long forms of the parasite,
the free flagellum is rudimentary or absent. Nevertheless, in the blood
of naturally infected animals flagellated forms were sometimes seen,
and these may even persist for a time in the inoculated animals. These
observations confirm those of Button and Todd, and show that the forms
1 [G. Martin, ' Les Trypanosomiases de la Guinde Frangaise,' Paris, 1906,
pp. 1-120, with several figures and maps, A. Maloine ; also C. R. Soc. Biol., v. 61,
1906, pp. 107-109. The account given of these diseases is taken almost verbatim
from Martin's summary (Chap. I.) in his monograph.]
15—2
228 TRYPANOSOMES AND THE TRYPANOSOMIASES
with free flagellum may exist for some time and then disappear. It will
be remembered that Martini observed similar morphological changes
in his two Togo trypanosomes.]
[Animals infected spontaneously are wasted and walk slowly and with
difEculty, owing to great weakness of the posterior extremities ; the
hair falls off, digestion is impaired, and blindness is not infrequently
observed.]
[Rats, mice, and guinea-pigs were susceptible to all the strains of
T. dimorphon met with. Rats died in 14 to 30 days ; mice died either fairly
quickly (5 to 11 days) or slowly (40 to 48 days); guinea-pigs died in 12,
39, and 57 days ; a rabhit died in 23 days. Monkeys (Cercopithecus calli-
trichus) died in 43 days, 3 months, and 5 months. A heifer lived 54 days ;
cats, ig, 20, and 151 days; dogs, 11, 16, 22, 30, and 97 days; a sheep
3 months and 13 days. In all the animals the spleen was much enlarged.
To put it briefly, after a fairly long incubation period, these different
strains of trypanosomes produced in all the experimental animals sub-
acute or chronic infections, resembling one another and also those observed
with T. dimorphon.]
[Differentiation by Laveran and Mesnil's method with cured animals
was not possible, for Martin's animals did not acquire immunity. A
billy goat and a sheep, cured of the natural disease (blood not infective
in doses of 20 c.c. and 15 c.c. for dogs), were re-inoculated with a trypano-
some from a guinea-pig and a laboratory strain of T. dimorphon respec-
tively. Ten days later the blood of both animals was infective for
mice, and the goat and sheep themselves showed parasites in their blood
in 24 and 16 days respectively after injection. No difference could be
made out between the two parasites. We shall see (Chapter VII.) that
Thomas and Breinl had similar cases — a sheep apparently cured of
T. dimorphon developed a fresh infection and died. The natives in Guinea
often stated that sick animals could recover, then have a recurrence the
following year and die.]
[The other trypanosome found in horses, cattle, and goats
closely resembles T. cazalboui. In fresh blood it is very motile. In
the horse the total length is 26 /^ to 28 /^, free flagellum 6 /x to 7"5 /«. ;
in cattle the total length is 22 /x to 28 /*, free flagellum 6 fi to 8 fj..
This trypanosome is not pathogenic for guinea-pigs, rats, or dogs.]
[On one occasion, in a Kankaya cow, Martin found a giant trypanosome,
very long and with a very active undulating membrane, but which,
nevertheless, travelled very slowly, gliding between the red corpuscles
without displacing them, after the manner of a spirillum. The flagellum
was well developed. Only one such trypanosome was seen in several
films examined. The blood of the cow was injected into a rabbit,
guinea-pig, and rat without result. Centrifuging the cerebro-spinal fluid
also failed to discover any more parasites. The animal was a hide-bound
skeleton, and had lost nearly all its hair. Two months before it was seen
it had given birth to a still-born calf.]
[Human trypanosomiasis is also very prevalent throughout
Guinea.]
[Many species of Glossina have been found in this vast area.
Gl. tachinoides, Gl. longipalpis, and Gl. fusca occur at Boke and
elsewhere along the banks of the Rio-Nunez, but it is G I. palpatio
and Gl. morsitans that are the most widely distributed and practically
universal.]
[Other biting flies found here include several species of Tabanidas,
and one or more species of Hippobosca.~]
CHAPTER VII
TRYPANOSOMIASIS OF HORSES IN GAMBIA
Pathogenic Agent : Trypanosoma dimorphon, Button and Todd,
1904.
[Section 1, — The Geographical Distribution of the Disease.]
This trypanosomiasis was discovered by Dutton and Todd^ (1902),
during their investigations upon human trypanosomiasis, which was
itself discovered the year before by Dutton. These two investigators
explored the Gambia from September 2, 1902, to May 7, 1903, and
were able to examine thirty-six horses in all. Horses are very scarce
in Gambia ; Dutton and Todd estimate that there are not more
than a hundred throughout the colony, and the majority are of
Senegalese origin.
Of these thirty-six horses, ten had trypanosomes in the blood.
Eight of them were in the maritime districts (five at Cape St. Mary,
and three at Bathurst), whilst two were discovered a long way from
the sea, at Maka, a French station a little to the north of the River
Gambia. It is therefore probable that the disease occurs throughout
the British colony on the Gambia, and even extends to the neigh-
bouring regions in the basin of the Senegal.
During their stay at St. Louis and Dakar, on the Senegal, Dutton
and Todd examined, but with negative results, a number of sick
animals (horses, mules, cattle, and camels) coming from a region of
the Sudan where there is a disease with symptoms closely resembling
those of the trypanosomiasis of horses in Gambia.
Only one out of ten horses showing trypanosomes was really ill
at the time of the blood examination, and it died six days later. The
disease is so insidious that it escapes the otherwise acute observation
of the natives, who state that the animals die of simple inanition.
[The earlier statement of the authors that ' the horse appears to
be the only animal which suffers from the disease naturally, and that
cattle and other domestic animals do not become spontaneously
infected, although they are susceptible to experimental inoculation,' ^
needs modification in the light of recent researches. We have
already seen that Laveran, Cazalbou, and Pecaud, in studying the
^ Dutton and Todd, First Report of the Trypanosomiasis Expedition to Sene-
gambia (1902). Thompson Yates and Johnston Lab. Reports, v. 5, 1903.
^ [Laveran and Mesnil, in the original, p. 200.J
229
230 TRYPANOSOMES AND THE TRYPANOSOMIASES
trypanosomiases of Haut - Niger, found a trypanosome closely
resembling, if not identical with, T. dimorphon.^ Also that Laveran
and Martin described the same trypanosome in horses in French
Guinea, and that Martin found the same infection in Bovidje, and
very probably in sheep, dogs, and pigs, throughout Guinea.]
[In addition to the Gambia colony, Haut-Niger, and French
Guinea, this trypanosome appears to occur in the Shari basin
(Decorse). The trypanosomiasis in an ox in Sierra Leone, discovered
by Smith, was probably a dimorphon infection (see p. 119-]
[The trypanosomiasis of mules in the Bahr-el-Ghazal province,
discovered by Balfour, and that of cattle in Uganda (Jinja), dis-
covered by Nabarro and Greig, were in all probability also due to
T. dimorphon. ~]
[Button and Todd found a similar trypanosome in antelopes and
cattle all along the Congo from Leopoldville to Kasongo. Both long
and stumpy forms of T. dimorphon were seen in these animals.]
[It is therefore permissible to suppose, says Martin, that a wide
belt of the African continent, parallel with the Equator, and extend-
ing from Gambia and Guinea on the west to the Anglo- Egyptian
Sudan and Uganda on the east, is infected with T. dimorphon^
Section 2. — The Course of the Disease in Horses.
Spontaneous Infection in the Horse. — According to Button
and Todd, the following is a resume of the symptoms of the natural
disease in horses : The first symptom is loss of strength. The
temperature seldom rises above 39° C. [i02"2° F.]. The parasites are
scanty in the blood, sometimes ten being seen in a slide, but often
they are fewer, and they may even be absent for long periods.
Two or three weeks later the animal is really ill ; it wastes, hangs
its head, the eyes become dim, and weakness is very apparent. At
this time there are periodical rises of temperature, generally associated
with the presence of parasites in the blood.
The next month wasting becomes more marked, so that the ribs
are visible. It seems as though the flesh passes from the chest to
the abdomen, but, in spite of this enlargement of the abdomen,
there is no cedema. The scrotum is pendulous, and the testicles
hang so low that at first sight it seems as though they were
oedematous. Sometimes there is a slight watery discharge from the
eyes. In none of the sick horses did Button and Todd find definite
cedema of the abdomen, scrotum, or limbs, or staring of the coat,
which are usually so pronounced in horses suffering from nagana.
The stage of the disease just described lasted ten months in one
horse. Buring that time trypanosomes were seen in the blood only
on four occasions, each time in association with a slight rise of tem-
perature to about 39'5° C. [i03'2° F.].
1 [Laveran has recently come to the conclusion, however, that this trypanosome
is distinct from T. dimorphon (see p. 226).]
TRYPANOSOMIASIS OF HORSES IN GAMBIA 231
With the progress of the disease emaciation becomes gradually
more marked, so that the ribs and pelvis are very prominent. The
animal is now characteristically apathetic. CEdema is still absent ;
there is often a slight whitish discharge from the eyes, and sores
appear in the lumbar region where the bones project. There are
never any hsemorrhages, either from the mucous membranes or from
the kidneys. During this stage trypanosomes are almost constantly
present in the blood, often in large numbers. The temperature is
nearly always high (up to 40"5° C. [105° F.]) and fluctuating (see
Fig. 25, A).
Button and Todd saw two horses die of this disease. One of
them lingered for three days, scarcely able to raise itself owing to
extreme weakness ; the breathing was laboured ; there was almost
constant sweating, and just before death a slight convulsion. The
other horse, whose temperature chart is given in Fig. 25, A, died
almost suddenly. Shortly before death, but not earlier in the disease,
the animals showed a diminution of the red corpuscles and of haemo-
globin.
Post-mortem there was a yellowish, gelatinous cedema, of the
sheath, and in the first horse also of the abdominal walls. Amber-
coloured fluid was present in the peritoneal, pleural, and pericardial
cavities ; there was general enlargement of the lymphatic glands,
the spleen was not enlarged, the liver was fatty, the lungs congested.
It is impossible to give precisely the duration of the disease. One
horse was infected for more than a year. Of two colts a year old,
one was alive six months after the disease was recognised in it, while
the other died two months after. Possibly some horses recover from
the disease. [A naturally infected horse, which was brought from
the Gambia to England, was still alive and in excellent condition
two years and five months after it first came under observation ; but
its blood was still infective, though only in larger doses than formerly —
I to ih c.c. for rats, 3'5 c.c. for rabbits (Thomas and Breinl).]
The disease can only be diagnosed with certainty by finding the
trypanosome in the blood. It may, however, be suspected in animals
which look dejected, and have a temperature above 38*3° C. [101° F.].
The natural disease in horses to some extent resembles nagana
in its clinical history, but the symptoms are less definite, and the
disease runs a much more chronic course.
By means of the virus, for which we are indebted to Dutton,
Todd, and Annett, we have succeeded in infecting a certain number
of animals, including a horse. ^ The very complete account which we
are able to give of this horse confirms, and in certain respects com-
pletes, the description of Dutton and Todd.
Experimental Infection of the Horse. — The horse we
inoculated was strong and had particularly thick-set limbs. It
weighed 575 kilogrammes [about 1,265 pounds]. It was inoculated on
^ Laveran and Mesnil, C. R. Acad. Sciences, v. 138, March 21, 1904, p. 732.
232^'^TRYPANOSOMES AND THE TRYPANOSOMIASES
November 13, 1903, under the skin of the neck with ^ c.c. of diluted
blood of a rat containing many trypanosomes. Fig. 25, B, shows
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the temperature curve for two months from the day of inoculation,
and also the relative number of trypanosomes in the blood.
The horse never suffered from continued fever. There was a rise
of temperature to 39-4° C. [103° F.] on the eleventh and twelfth
days coincident with the appearance of trypanosomes in the blood.
TRYPANOSOMIASIS OF HORSES IN GAMBIA 233
After that there was an apyretic period of seven days, during which
the parasites could not be found on microscopical examination. On
the igth and 20th days the temperature rose to 41° C. [io5'8° F.], on
the 23rd and 24th days to 39'5° C. [io3'2° F.], and on the 29th day to
39"i° C. [i02"4° F.]. During this period, from the i8th to the 30th day,
a few trypanosomes were always found in the blood on microscopical
examination, and they continued to be present until the 53rd day,
although the temperature had become normal, except for a small
rise to 39° C. [102-2° F.] on the 42nd day. From that time the tempera-
ture was practically normal, and trypanosomes were found only
once, on the 8ist day. That they were still present, however, is
shown by the fact that | c.c. blood, taken on the 105th day, infected
a mouse, and blood taken on the 121st, 157th, and 183rd days pro-
duced, in doses of 2*5 c.c, an infection in rats after a prolonged
incubation period.
About the 50th day the scrotum was swollen, and two days later
there was a very characteristic large oedematous swelling near the
middle of the abdomen. This persisted for about one and a half
months and then entirely disappeared. No other external sign of
disease was seen, and the horse never seemed ill. [Seven months
after inoculation this horse had recovered, and 15 c.c. of its blood
was not infective on injection into a susceptible animal. It subse-
quently became infected with mbori. to which it succumbed.^]
We would draw attention to the oedema present in our horse,
which is like that seen in nagana, but which, according to Button
and Todd, does not occur in the sick horses in Gambia.
Section 3. —Course of the Disease in Mammals other than the
Horse.
[Button and Todd, Laveran and Mesnil, Thomas and Breinl,^
and G. Martin have investigated the effects of this trypanosome
upon various species of animals, and have found that most mammals
are more or less susceptible to T. dinwrphon. Martin's results with
the Guinea trypanosome, as well as those of Balfour and of Nabarro,
Greig, and Gray with those of the Sudan and Uganda, which were
probably also T. dimorphon, have already been given in different
Sections of Chapter VI.]
Rodents. — Rats, mice, guinea-pigs, and rabbits are susceptible.
In the rat, according to Button and Todd, the incubation period
varies from three to twelve days. Beath occurred, with one excep-
tion, in twenty to seventy days after inoculation. Trypanosomes
are nearly always present in the blood. Sometimes, when the disease
runs its course in twenty to twenty-five days, the trypanosomes
gradually increase in number until the end. In rats which are
1 [Information kindly furnished by the authors.]
^ [Thomas and Breinl, Thompson Yates and Johnston Lab. Reports, v. 6,
partii., 1905, pp. 25-31.]
234, TRYPANOSOMES AND THE TRYPANOSOMIASES
rather more resistant, the parasites diminish in number at times,
and they may even be absent on microscopical examination. In some
of these rats Button and Todd noticed oedema of the tunica vaginalis
and of the abdominal parietes, and occasionally a slight diminution
in the number of red corpuscles.
Our own observations agree with those of Button and Todd.
We find the average duration of the disease in ordinary white or
speckled rats to be twenty-three days (minimum ten, maximum forty-
two). As a rule trypanosomes are numerous in the blood. Post-
mortem the spleen is considerably enlarged, particularly in rats
which showed a certain resistance to the disease — for example, in a
rat weighing 125 grammes, which lived forty-two days, the spleen
weighed 5 grammes.
[Thomas and BreinP obtained very similar results with their rats.
One rat showed a marked degree of resistance to the parasite. It
developed a mild infection after the second intraperitoneal inocula-
tion, but it very soon recovered, and was then immune against large
doses of the virus.]
[Post-mortem the spleen was considerably enlarged in chronic
cases ; the lymphatic glands were also enlarged and often hsemor-
rhagic. Hsemorrhagic nephritis was noted in two chronic cases ; the
urine contained a few trypanosomes, and numerous small haemorrhages
were found under the capsule and in the substance of the kidneys.]
Mice, according to Button and Todd, are a little more susceptible
than rats ; incubation two to seven days, death in sixteen days to
one month. In our experiments white mice were about as resistant
as rats, some, however, living for months with the disease. One
animal will suffer from a fairly acute infection lasting at least a
week, while another may have a chronic infection lasting some-
times more than five months, but always terminating fatally. In
the one case, as in the other, trypanosomes are generally numerous
in the blood during the course of the disease. In very chronic
cases the enlargement of the spleen, which may be enormous,
is quite characteristic. The mouse becomes deformed, and on
palpation the hypertrophied spleen can easily be felt as an abdominal
tumour. In two mice, weighing 24 to 25 grammes, in which the
disease lasted 92 and iil days, the spleens weighed 2*62 . and
2'55 grammes respectively. Even when the disease runs its course
in from one to two weeks, the spleen of a mouse of 20 grammes never
weighs less than 0'4 gramme ; that is to say, six times the normal
weight.
One of our mice deserves special notice, as it died five and a half
months after infection.
Inoculated November 12, 1903 ; trypanosomes present November 18 ;
died April 24, 1904. During November and December it had three
' [Thomas and Breinl, Thompson Yates and Johnston Lab. Reports, v. 6,
part ii., 1905, pp. 25, 26.]
TRYPANOSOMIASIS OF HORSES IN GAMBIA 235
injections of human serum, which caused the trypanosomes to disappear
for a very short time. During January parasites were always found on
examining the blood, sometimes in large, sometimes in small numbers.
From the middle of February trypanosomes were always numerous or
very numerous in the blood. From January 15 the spleen was enormous ;
at the autopsy it weighed 3 grammes, the mouse weighing only 27
grammes.
The trypanosomes in this mouse were attenuated in virulence. Thus,
a rat inoculated subcutaneously on March 2 did not show trypanosomes
in its blood until April 2. Two mice were inoculated on March 18. One,
moculated intraperitoneally, showed parasites on the 30th and died
April 4, while the other, inoculated subcutaneously, did not show any
trypanosomes in its blood until April 8. On different occasions we
found, on microscopical examinations of stained specimens, numerous
intraleucocytic trypanosomes, always spherical in form, but recognisable
by their nucleus and centrosome. We never succeeded in observing the
engulfment of normally shaped trypanosomes. During the last few days
of life the mouse lost much of its hair.
Two guinea-pigs inoculated by Button and Todd died in 29 and
31 days ; incubation period 8 and 4 days respectively. The tempera-
ture was between 39-5° and 40° C. [103-2° to 104° F.]. Trypano-
somes were nearly always present on microscopical examination, and
were numerous at the time of death. We likewise inoculated two
guinea-pigs, which died in 24 and 30 days. During the last few
days of life trypanosomes were fairly numerous. The spleen was
found slightly enlarged.
[Thomas and BreinI (op. cit., p. 26) found the incubation period to
vary from 4 to 15 days, average 4 to 6 days ; the disease lasted from
9 to 60 days. The temperature was usually slightly raised when the
parasites first appeared, but after that it varied little from the
normal. There was moderate anaemia and loss of weight. Trypano-
somes gradually increased in number, until there were as many as
forty to sixty to a field. These high numbers continued for ten
days before death, or there was a diminution coincident with a
leucocytosis. In the more chronic cases there was marked periodicity
in the number of the parasites.]
[Rupture of the spleen occurred in seven cases, five of which
were of the very acute type. Enlargement of the glands was not
marked in any of the guinea-pigs.]
A rabbit inoculated by Button and Todd had an incubation
period of 13 days, and died 53 days after inoculation. Its tempera-
ture was constantly raised and even reached 42° C. [107-6° F.].
Two rabbits we inoculated subcutaneously died in 76 and 115 days,
after an incubation period of about 12 days. Parasites were always
scanty on microscopical examination. The first rabbit died in an
anaemic and cachectic condition, while the second appeared paralyzed
the day before death, but had not lost weight. The spleen weighed
20 grammes, the weight of the rabbits being about 2 kilogrammes.
[Thomas and BreinI found the incubation period in rabbits to vary
from 4 to 15 days. It was shortest after intravenous inoculation.
336 TRYPANOSOMES AND THE TRYPANOSOMIASES
longer after intraperitoneal, and longest after subcutaneous injection.
The disease ran an acute course in some animals, death occurring in
26 to 35 days after intravenous inoculation. In others the disease
was more chronic, and lasted 78 to 157 daj's. Trypanosomes were
sometimes present in large numbers in acute cases, but not nearly so
frequently as in the gumea-pig. In the more chronic cases there
was marked periodicity in the number of parasites seen in the blood.
Profound anaemia, loss of weight, staring of the coat, and slight
oedema of the hind-limbs and base of the ears, were the chief symptoms
noted. Discharges from the eyes, nose, and genitals were rarely
seen. The temperature was raised with the first appearance of
the parasites, then became irregular, often showin"g considerable
elevations, and towards the end became subnormal. The spleen
and lymphatic glands were found enlarged.]
Monkeys. — A mangrove monkey {Cercopithecus ?) inoculated by
Dutton and Todd showed parasites in its blood four days after
subcutaneous injection of blood rich in trypanosomes. Unfortu-
nately, it escaped the following night.
Three baboons (Cynocephalus sphinx) inoculated by Dutton and
Todd were absolutely refractory, for their blood in doses of as much
as 3 or 3j c.c. was not infective for rats. Thomas and Linton,
continuing these researches at Liverpool, succeeded in infecting a
baboon.
[The temperature was irregular, and loss of weight was marked,
especially when the parasites 'were first seen. The baboon died
six and a half months (204 days) after inoculation. Its spleen and
lymphatic glands were slightly enlarged. Thomas and Breinl also
successfully inoculated a Cercopithecus callitrichus, a Macacus rhesus,
and a Jew monkey with this trypanosome. The first died in 160 days,
and the last in 75 days after inoculation. The Macacus became
infected on the seventh day, but after this parasites were hardly
even seen, and the monkey died finally from dysentery.]
We have injected the T. dimorphon into a baboon, but, like
Dutton and Todd, with a negative result.
Dogs. — Interesting results have been obtained with dogs. Three
young dogs inoculated by Dutton and Todd died in ig, 32, and
36 days (after an incubation period of less than 8 days, 11 days,
and 3 days respectively). The animals had remittent fever, and
trypanosomes were constantly present in the blood.
An adult dog inoculated by us behaved similarly : Incubation
period 10 days ; death in 25 days ; fever continued (see Fig. 26) ;
trypanosomes almost constantly present on microscopical examina-
tion, and fairly numerous a few days before death. Through-
out the disease there were no obvious physical signs externally, and
post-mortem the only lesion found was enlargement of the spleen,
which was about six times the normal size (weight, 97 grammes in
a dog of 7|- kilogrammes).
TRYPANOSOMIASIS OF HORSES IN GAMBIA 237
Button and Todd inoculated a dog ( '^ ) which was alive ten and
a half months later. At first the disease resembled that seen in the
other dogs : Incubation period nine days ; trypanosomes constantly
present in the blood in small numbers for four months ; and rises of
temperature to 40-2° C. [i04'4° F.] at the first appearance of trypano-
somes in the blood, and to 39° or 40° C. [i02'2° or 104° F.] with
each recrudescence of the parasites. Since that time the dog has
always been in good health, and has undoubtedly recovered, for
in the tenth month 2J c.c. of its blood were no longer infective.
[This bitch was brought to England, and was still alive three years
after inoculation. While in England it had pups, which were found
JOUl^S
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Fig. 26. — Tempeeatdre Chart of a Dog infected with T. dimorplwn.
O indicates absence of trypanosomes ; + , present but scanty ; + + , fairly numerous ;
+
+ +'
, numerous.
to be quite as susceptible as normal pups, and to succumb in the
usual time. The serum of the bitch was not protective.]
[Thomas and Breinl found the incubation period to be 4 to
8 days, and the total duration of the disease 10 to ig days in adult
dogs, 9 to 26 days in puppies. Trypanosomes were almost con-
stantly present; fever was irregular or continuous, the tempera-
ture being usually subnormal before death ; loss of weight and
anaemia were prominent features. Post-mortem the spleen was
often considerably enlarged (two or three times the normal size).
The lymphatic glands were enlarged and sometimes hasmorrhagic]
[Cats. — Four cats and two kittens were inoculated by Thomas
and Breinl. The incubation period was 12 to 14 days in adult cats,
and 75- days in a kitten. In the former the disease was chronic
(9 to 10 months), but a kitten died in 23 days. In the full-grown
animals the parasites were scanty, and appeared in the blood at
irregular intervals ; in the kitten they were constantly present
and in greater numbers. The temperature was raised, but irregular,
in all the animals, being higher in the acute disease (kitten). In the
chronic form (adults) the anaemia and loss of weight were not so
238 TRYPANOSOMES AND THE TRYPANOSOMIASES
pronounced as in the acute form in the kitten. In both forms
there was at times a discharge from the eyes or nose.J
[Two cats aborted during the infection, but the blood of the
foetuses was not infective on injection.]
[Post-mortem the spleen was enlarged in all cases, but more in
the acute than in the chronic cases. The lymphatic glands were not
much enlarged.]
Cattle. — Dutton and Todd inoculated a calf ((?) six months
old and an ox. Nine days later in the former and twelve days later
in the latter animal some trypanosomes were found on centrifuging
the blood. Trypanosomes were always scanty in the blood, that of
the ox, for example, showing usually only three parasites in j c.c.
In the calf the temperature rose to 40'6° C. [105° F.] two days
after inoculation, but fell again the next day ; it was raised again on
the seventh to the ninth days, and also on the eleventh day ; on the
eighteenth day there was another small rise. The animal died
twenty days after inoculation. In the ox the temperature was below
39° C. [i02"2° F.] for the first twenty days, but towards the end of
the first month it rose to 40-5° C. [105° F.] for two days. The
animal died forty day's after inoculation. Cattle, therefore, appear
to be very susceptible to the Gambian trypanosomiasis, yet Dutton
and Todd never met with a case of natural infection in these
animals.
Post-mortem there was nothing characteristic except, perhaps,
enlargement of the lymphatic glands, which were congested or
oedematous.
Goats. — Two goats were inoculated by Dutton and Todd, who
found the incubation period to be three or four days. During the
following two or three weeks a few parasites were occasionally seen
in blood-films. At the first appearance of the trypanosomes the
temperature rose to 407° C. [io5'2° F.], and this was followed by
irregular fever. The two animals were still alive nine months and
ten and a half months after being inoculated, and the blood of one
of them was found to be still infective five months after inoculation.
[These two goats were brought to England in 1903, and sub-
sequently appeared to have recovered. The blood of goat i was not
infective for animals in doses of 2 to 3 c.c. nine months after inocula-
tion, but this goat had not become immunized, for it was successfully
re-inoculated by Thomas and Breinl, and succumbed to the infection.
Goat 2 had apparently recovered a year after inoculation, but five
months later, when accidentally killed, loo c.c. of heart blood
infected a guinea-pig after a prolonged incubation period. The
serum of these goats did not cause any permanent agglutination.]
We have also infected two goats by injecting under the skin
of the ear blood of a rat containing T. dimorphon. Goat i died in
twelve and a half days with an acute infection. Six days after
inoculation the temperature rose to 39"5° C. [103-2° F.] ; on the next
TRYPANOSOMIASIS OF HORSES IN GAMBIA 239
two days it was 40"6 C. [105° F.], and on the succeeding days 41°, 40"5°,
40-5°, and 39-5° C. [105-8°, 105°, 105°, and I03'2° F.]. Trypanosomas,
scanty seven days after inoculation, were numerous from the eighth
day until death. Goat 2 was inoculated on December 28, 1903. The
disease began, as in goat i, with high fever and many parasites in
the blood ; but later the temperature, after a series of oscillations,
gradually returned to normal (see Fig. 27), and the trypanosomes
became scanty in the blood. For the first month they were almost
constantly present at the daily blood examination, but after that
time they diminished very much in number, so that on several
occasions they could not be found. [The goat lived for twenty-one
and a half months after inoculation, and at death T. dimorphon was
still present in considerable numbers.]^ The course of the disease
Dales ^«
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Fig. 27. — Temperature Chart of a Goat infected with T." dimorphon.
The signs O, +, etc., have the same significance as in Fig. 26.
in this goat closely resembled that in the two goats inoculated by
Button and Todd.
Sheep. — Button and Todd infected a native sheep six months
old. Trypanosomes appeared in the blood in eight days, and were
numerous during the following week. Later they were still present
but scanty, and finally they disappeared. With the first appearance
of the parasites the temperature rose to 4i'9° C. [i07-4° F.], which
was followed by irregular fever, with rises to 40-5° or 41° C. [105° to
T05'8° F.] The animal died, without showing any symptoms, 182
days after inoculation, on its way to England.
[Thomas and Breinl inoculated a ram intraperitoneally. On the
sixteenth day there was a slight rise of temperature, and trypano-
somes were seen in the blood. Ten days later they were numerous
(ten to forty in a field), and continued so for a week. After this
they diminished, and remained scanty until death, which occurred
eighty-four days after inoculation. Anaemia was constant, and the
animal wasted rapidly. Post-mortem there was no enlargement of
the spleen or lymphatic glands.]
Birds. — Two fowls were inoculated several times, but un-
successfully, by Button and Todd.
1 [Information furnished by the authors.]
240 TRYPANOSOMES AND THE TRYPANOSOMIASES
In conclusion, T. dimorphon gives rise in those mammals which
have hitherto been experimented upon either to an acute or subacute
disease (as in rodents, dogs, and cattle), or to a chronic infection (as
in goats, sheep, [monkeys, and cats]) ; but the disease is never so acute
as that caused by T. hrucei. Baboons are, as a rule, refractory.
[Changes in the Organs induced by T. dimorphon. — These have
been studied by Breinli in artificially infected monkeys, dogs, rabbits,
guinea-pigs, and rats.]
[The leptomeninges of the brain and spinal cord were very congested
in all the chronic cases. On section the grey matter was also congested,
and showed many small hsemorrhages. The liver and spleen were much
congested, the latter often showing haemorrhages in its substance.]
[Microscopically, the perivascular spaces in the grey matter of the
nervous system were often filled with red blood-corpuscles, pigment
granules, and a few leucocytes. The spleen showed extreme congestion,
especially near the periphery where frequently only red blood-corpuscles
were to be seen. Many hyaline cells were present containing red blood-
corpuscles and much blood-pigment. There was great proliferation of
the endothelium of the vessels, so that in some places these appeared to be
obstructed.]
[The lymphatic glands presented marked changes. Very often the
lymphoid tissue was much reduced ; the spaces between the bands of
lymphoid tissue network contained a few lymphocytes, hyaline cells with
two or more nuclei, cells with a large quantity of included pigment
giving the iron reaction, and very many large free pigment granules.
In some cases, in which the spleen contained only traces of pigment, the
glands were practically filled with it (Breinl). The degree of pigmenta-
tion increases with the duration of the infection.]
[The cells of the liver and kidneys were often degenerated, being fatty
and atrophied. Blood-pigment was often found in the liver.]
Section 4. — The Trypanosoma dimorphon.
In a fresh blood-film this trypanosome can be easily identified,
on account of the great difference in size of the various forms.^
There are parasites 20 /i to 25 /^ long, which in their general appear-
ance closely resemble T. hrucei, the only difference being that the
anterior part is less slender or drawn out, the reason of which
we shall see presently. Other parasites are not more than 12 /a
long ; the posterior end is quite rounded off, and the body becomes
gradually thinner right up to the anterior end. These forms have a
very characteristic movement. They move from place to place by
twisting on themselves like a tadpole, then suddenly they stop and
start again in a similar fashion, the undulating membrane being
only slightly visible. Between these two extreme types there are
all kinds of transitional forms.
In stained specimens these various forms are also seen, but as
our own observations are not entirely in agreement with those of
1 [Breinl, op. cit, pp. 87-89.]
^ [We have seen, however (p. 226), that a trypanosome, morphologically re-
sembling T. dimorphon, occurs in the French Sudan, .and that Laveran has
concluded that these two trypanosomes are distinct species.]
TRYPANOSOMIASIS OF HORSES IN GAMBIA 241
Button and Todd, we shall give first a r6sum6 of their observations
and then our own.
Button and Todd distinguish three forms of the parasite :
(i) ' Tadpole forms.' These are 11 /* to 13 ,«. long, by o"8 fito 1 /j-
wide. The free flagellum is very short, the centrosome almost at the
end of the body, and just in front of it there is a clear space. A few
chromatic granules are present. The body increases in size before
dividing by fission. This form of the parasite is seen in the horse,
rat, and mouse at the beginning of an infection, but tends to
disappear later.
(2) ' Long forms.' These are 26 ^ to 30 /«. long, by i'6 « to 2 ^ wide.
The body is long and slender, and there is a long free flagellum.
The posterior extremity (post-centrosomic part) measures from i'6 /m
to 3'2 /J,, and resembles the head of a pike. There are no blue-
staining protoplasmic granules. This form predominates in the
blood during the days which precede the death of the animal.
(3) ' Stumpy forms.' The body is short (16 /j, to 19 fi) and squat
(3'5 A' wide) ; the free flagellum is very short, and no division forms
are seen. The centrosome is quite close to the rounded posterior
extremity, and in front of it a clear space can usually be made out.
The protoplasm contains several chromatic granules. This form is
very common in the blood when the disease is not yet far advanced.
It really does not differ from the so-called ' tadpole form,' and the
three forms may, therefore, be reduced to two. This is the origin of
the name dimorphon suggested by the investigators of the Liverpool
School of Tropical Medicine to designate the trypanosome of horses
in Gambia. (Letter from Br. Annett, Becember 18, 1903).
We ourselves have not been able to see any difference
between the ' tadpole ' and ' stumpy ' forms. We have seen short
parasites, 10 /i to 15 /u, long, by 07 /x to i'5 /ti wide, but have never
seen forms 3 '5 /a wide in good blood-films, and the same remark
applies to the spherical forms which Button and Todd say are
derived from the ' stumpy ' forms. We recognise the existence of a
short form and a long form (average length 22 (jl ), the width of the
former being about i /i, and of the latter about i'5 fx. The short
form cannot be looked upon as a young individual of the large form,,
because each form multiplies by longitudinal fission.
It is particularly with regard to the long form that we differ from
the English investigators, who describe and figure a long free
flagellum. According to our own observations, the protoplasm of the
body is continued along the flagellum almost or quite to the end. As a
result, the really free part of the flagellum is very short, or even absent,
in the long form as well as in the short. We have already pointed
out a similar appearance in T. brucei just after division, but in the
case of T. dimorphon all the parasites occurring in the blood show it..
[Thomas and Breinl and G. Martin agree with Laveran and
Mesnil as to the absence of Button and Todd's long form, witk
16
242 TRYPANOSOMES AND THE TRYPANOSOMIASES
long free flagellum, from the blood of subinoculated animals. But
we have already seen (Chapter VI., Section ii) that in the blood ot
naturally infected sheep in Guinea, Martin found trypanosomes with
a long free flagellum, and that these flagellated forms even persisted
for a time in the blood of experimental animals.]
As already stated, transitional forms exist between the short and
long varieties (see Fig. 28, / to 4). Some long forms have a pointed
post-centrosomic end (Fig. 28, / and 5) ; others (Fig. 28, 2) have a
rounded end, like all the short forms; while Fig. 28, <5, shows an
intermediate condition. The undulating membrane is never well
developed; in the small forms it is closely applied to the body
proper.
Fig. 28, 5 to 7, represents the stages of division in a long form
(Fig. 28, s and 6), and in a form transitional (Fig. 28, 7) between
Fig. 28. — Trypanosoma dimorphon.
I and 2. Long forms. 3. Intermediate form. 4. Short form. 5, 6, and 7. Dividing
forms. (Magnified about 2,000 diameters.)
the short and long forms. The mode of division is the ordinary
longitudinal fission into equal or subequal parts.
There is one other point to be mentioned, namely, that the proto-
plasm of all the forms of T. dimorphon stains a very deep blue, and
only very exceptionally are protoplasmic granules visible.^
We have seen parasites with pale-staining protoplasm, as
mentioned by Dutton and Todd, and compared by them with the
hyaline forms of T. brucei of Plimmer and Bradford. We think
that, in this case as in the other, they are involution forms.
The morphological differences between T. dimorphon and the
trypanosomes of the type brucei are so obvious that it is unnecessary
to dwell upon them.
An interesting feature of T. dimorphon is its great tendency to
agglutinate as soon as the blood of a rat or mouse containing many
parasites is placed on a slide and covered with a cover-glass.
1 [Thiroux and Teppaz state that they often found protoplasmic granules in this
trypanosome, as Dutton and Todd had done. They also describe endocorpuscular
forms of the parasite.]
TRYPANOSOMIASIS OF HORSES IN GAMBIA 243
[Thomas and Breinl and Martin have also noticed this phenomenon .
The first two observers saw it with the blood of rabbits and guinea-
pigs, as well as with that of rats and mice.]
In stained specimens many trypanosomes are seen in pairs, but
instead of the two posterior ends facing one another, as is the case
with T. hrucei and T. lewisi, the two parasites are in contact laterally
for a poirtion of their length, so that frequently the centrosomes are
on the same level.
We have exposed to liquid air citrated and diluted rat's blood
containing many trypanosomes. This blood, before the action of
liquid air, injected in doses of two drops, killed mice in thirteen and
fifteen days. After fifteen minutes' exposure to liquid air, most of the
parasites were killed, but some survived, for the blood, in doses of
J c.c, killed mice in twenty-seven and thirty-two days. After one
hour's exposure to — igi° C. a few active trypanosomes were present,
yet the blood failed to infect two mice in doses of i c.c. Blood, kept
for twenty-four hours at — 191° C., which on microscopical examina-
tion showed only some small spherical bodies, did not infect on in-
jection. The mice inoculated with the blood cooled for one hour
and for twenty-four hours did not acquire any immunity.
We made only one attempt to cultivate T. dimorphon in Novy
and McNeal's medium. Under those conditions we kept the try-
panosomes alive for more than a month at 25° C, but from the
fourteenth day onward they constantly diminished in number.
During the second fortnight we saw forms with three, and even four,
flagella, which appeared to us to be true multiplication forms ; but
development stopped there, and subcultures were unsuccessful.
[Using a slight modification of Novy and McNeal's medium (the
same as they used for T. gambiense ; see Chapter XII.), Thomas and
Breinl made a number of culture experiments with T. dimorphon..
Cultures made at 22° C. were infective for animals up to the
twenty-third day, when injected in large amounts. Subinoculated,
but non-virulent, cultures remained alive as long as the fifty-sixth
day. In one case two feebly motile trypanosomes were found, in a
second generation tube, on the seventy-sixth day.]
Section 5. — Individuality of Trypanosoma dimorpJion.
The tr3'panosomiasis of horses in Gambia existing side by side
with human trypanosomiasis, it was necessary to ascertain whether
the two causal agents of these diseases, T. dimorphon and T. gambiense,
were really distinct species. We agree with Button, Todd, and
Annett in answering this question in the affirmative, for the following
reasons : (i) Morphologically, T. dimorphon differs from T. gambiense
as well as from the other well-defined trypanosomes. (2) Animals
which have acquired immunity against T. gambiense are susceptible
to T. dimorphon, as we have shown to be the case with mice. We
16 — 2
244 TRYPANOSOMES AND THE TRYPANOSOMIASES
may add that in all these mice (six in number) the dimorphon
infection was always acute. (3) Human serum, which has no action
upon T. gambiense (see later), has a marked effect upon T. dimorphon,
though less than it has upon the parasites of nagana, surra, and
caderas.
It was equally advisable to compare T. dimorphon with the
parasites of the other animal trypanosomiases. The morphological
differences between T. dimorphon and the other trypanosomes, and
the details of its effect upon various susceptible mammals, already
left little doubt about its individuality. After our two experiments
on the goats quoted above, there can remain no doubt at all about it.
Goat I, which died so rapidly, had, as a matter of fact, become
immunized against the nagana of Zululand, against caderas, and against
the surra of Mauritius (see its history in Chapters VI., VIII., and IX.).
It was infected with nagan* from October 25, 1901, till March, 1902 ; with
caderas from November 8, 1902, till April, 1903; and with surra from
June 5, 1903, till the end of October, 1903. After recovery from each
infection it was tested with the virus from which it had just recovered.
In addition, it was tested with nagana on May 20, 1903, and December 15,
1903, but did not become infected (on the latter occasion, however, the
T. hnicei remained in the blood at least a week). On December 28, 1903,
it was inoculated with T. dimorphon.
Goat 2 was immunized against caderas and surra. We have already
seen that these two goats were very susceptible to inoculation with
T. dimorphon, especially Goat i, which succumbed in twelve and a half
days.
Section 6. — Mode of Propagration.
Glossina palpalis^ is prevalent in Gambia along the banks of the
rivers and in the brushwood as much as two miles from any water.
This fly is particularly abundant in the mangrove swamps. On the
other hand, under similar conditions it would appear to be absent
from the Senegal.
Button and Todd made a certain number of experiments to show
the possible part played by this fly in the transmission of the
Gambian trypanosomiases. Flies caught in a locality where five
horses out of six suffered from trypanosomiasis did not infect three
white rats (44, 69, and 62 flies respectively were allowed to bite
these rats). Other flies were placed upon a rat after having previously
fed on an infected horse and rat. All these experiments gave negative
results.
Button and Todd had similar failures with the two species of
Stomoxys, which are very plentiful on the Upper Gambia. They
think that possibly their failures were due to the fact that the
1 [Mr. Austen informs me that the Gambia tsetse-fly is a local race of GL
palpalis, with femora and abdominal markings pale. He thought formerly that
this fly was the Gl. papalis, var. fachinoides, but since examining a long series of
specimens from Northern Nigeria he has come to the conclusion that Gl.
tachinoides, Westwood, is a species perfectly distinct from Gl. palpalis. — Ed.]
TRYPANOSOMIASIS OF HORSES IN GAMBIA 245
experiments were made during the dry season. Possibly they were
also due to the animal chosen for experiment — namely, the rat.
[In French Guinea and other parts of Africa, in which the
dimorphon'^ infection exists, several other species of Glossina, notably
Gl. luorsitans, as well as other biting flies (Tabanidse, Hippobosca),
have been shown to occur. It will be remembered, too, that Nabarro
and Greig, in Uganda, were able to convey the Jinja virus (probably
T. dimorphon) from infected to healthy monkeys by the bites of
Gl. palpalis.']
Section 7. — Treatment.
One of us^ has made some experiments with arsenic, in the form
of sodium arsenite, and with human serum. Both have some effect.
Human serum injected in sufficient doses into mice and rats with
many T. dimorphon in their blood usually causes the parasites to
disappear in thirty-six or forty-eight hours, but they soon reappear.
In cases in which the trypanosomes are numerous, the only effect
of the injection of human serum may be to diminish the number of
parasites. The action of human serum is therefore quite definite,
but less than in nagana, surra, and caderas.
Arsenious acid also has an effect upon T. dimorphon, but
apparently less than it has in the case of other trypanosomiases.
We have also studied the action of trypanred upon T. dimorphon
in mice ; it causes a temporary disappearance of the parasites from
the general circulation.^
1 [Thiroux and Teppaz {Ann. Inst. Past., v. 21, 1907, pp. 211-223) state that
this trypanosomiasis is present in the region of Nianing and in other parts of
French Sdn^gal. Many biting flies occur there, including Gl. palpalis and
Gl. longipennis .^
- [Laveran, C. R. Acad. Sciences, v. 138, Feb. 22, 1904, p. 450.
^ [See also Chapter XIII., on Treatment.]
CHAPTER VIII
SURRA
Pathogenic Agent r Trypanosoma evansi, Steel, 1885.
This name has been used from time immemorial by the natives of
certain parts of India for a disease of horses characterized by
profound cachexia, without any lesion post-mortem to account for
this cachexia. As a result of the researches of the last twenty-five
years, we now know that surra occurs naturally, not only in horses,
but also in other Equidse, in camels, and in cattle. Epizootics have
also been recorded among sporting dogs in certain parts of India.
According to G. H. Evans (quoted by Lingard), elephants in Burmah
are also affected by the disease.
The disease closely resembles nagana, in being a kind of per-
nicious anaemia, with remittent or intermittent fever, wasting (in
spite of a healthy appetite), oedema of the limbs and belly, frequent
lesions of the eyes and eyelids, great muscular weakness, and
terminal paresis. In horses the disease lasts from one to two
months, sometimes less ; in the camel it may run a similarly rapid
course, but usually it lasts three years, whence the name Tibarsa,^
which means three years, given to the disease in camels in some
parts of the Punjab.
Cattle in India are resistant as a rule, and for a long time this
was looked upon as the most important difference between surra
and nagana. In Mauritius, where the disease has recently been
introduced from India, the mortality amongst cattle has been
considerable.
Section 1 . — Historical. Geographical Distribution of the Disease.
In 1880 Griffith Evans,^ working in Dera Ismail Khan (Punjab),
near the Indus, discovered in the blood of horses, mules, and camels
affected with surra a filiform, very motile organism, which at first he
took to be a spirillum. He soon recognised, however, as did Lewis,
who had just discovered the flagellate of the blood of rats, the
animal nature of the parasite. He concluded that the characteristic
^ [See Pease, ' Tibarsa Surra,' \r\Journ. Trap. Vet. Sc, v. i, 1906.]
2 G. Evans, ' Report on Surra,' published by the Punjab Government, Military
Department, December 3, 1880.
246
SURRA 247
parasite found by him in the blood was the immediate cause of surra.
By means of subcutaneous inoculation of blood he succeeded in
giving the disease to the dog and horse.
J. H. Steel/ in 1885, found the same organism in the blood of
transport mules in British Burmah. He regarded it as allied to the
parasite of relapsing fever, and called it Spirochcsta evansi. He trans-
mitted the disease to the monkey {Macacus) and dog.
Crookshank,^ in London, examined films of camel's blood sent to
him by Evans, and described the chief characteristics of the parasite
— e.g., the undulating membrane, its relation to the flagellum, etc.
This hffimatozoon is now universally known as the Trypanosoma
evansi (Steel).
The discovery of Evans and Steel was soon confirmed by a
number of medical and veterinary practitioners in India — Vandyke
Carter, Gunn, C. E. Nuttall, etc., and especially Lingard.^
Since then the name surra could be used in a fully specific sense,
and at the same time it was necessary to widen its meaning so as to
include all the pathological conditions produced by the hsematozoon
of Evans in different species of animals.
From investigations made during the past twenty years in India
and Burmah, and which are summarized in Lingard's various
Reports published from 1893 to 1899, it appears that under the
heading surra must be included a large number of diseases bearing
different names, according to the district in which they occur, the
particular species of animal affected, and the most prominent
symptom.*
[Until it was demonstrated by Vallee, Panisset, and Laveran
that mbori, the trypanosomiasis of dromedaries in the Sudan, first
described by Cazalbou, is merely a variety of surra, this disease
was not known to occur on the continent of Africa. Further investi-
gations may show that many of the other trypanosome epizootics
described in various parts of Africa (see Chapter VI., Part II.) are
true surra, or members of the ' surra ' group of diseases. Novy,
McNeal, and Hare,^ in their paper on ' The Cultivation of the Surra
1 J. H. Steel, Report on his investigation into an obscure and fatal disease
among transport mules in' British Burmah, 1885.
2 Crookshank, ' Flagellated Protozoa in the Blood of Diseased and Apparently
Healthy AnimaXs,' /ourn. 0/ i/ie Roy. Micros. Soc, December, 1886, plate 17.
Crookshank classed the parasite of surra with the Hamatomonas (flagellates in
the blood of fishes) of Mitrophanov ; the only mistake he made was to place the
genus Hcematomonas in another genus of Flagellata, Trickomonas. Osier (Brii.
Med. Journ., March 12, 1887) reintroduced the genus Hcematomonas j lastly,
Balbiani {Journ. de Micrograpkie, 1888, p. 399) adopted the old generic name of
IGruby, Trypanosoma.
2 H. Vandyke Carter, 'Scientific Memoirs by Medical Officers of the Army
of India, 1887,' Calcutta, 1888. Alfred Lingard, 'Report on Horse Surra,' v. i,
Bombay, 1893. Summary of ' Further Report on Surra,' Bombay, 1894. Ibid.,
1895. Annual Report of the Imperial Bacteriologist for the official year 1895-1896.
Report on ' Surra in Equines, Buffaloes, and Canines, etc.,' v. 2, Bombay, 1899.
* Consult p. I of Lingard's last Report in this connection.
^ [Novy, McNeal, and B.a.re, /ourn. of the Ainer. Med. Assoc, May 28, 1904.]
248 TRYPANOSOMES AND THE TRYPANOSOMIASES
Trypanosome of the Philippines,' even go so far as to suggest, on
morphological grounds alone, that the Mauritian and Philippine
trypanosomes are probably distinct species.]
In 1886 Blanchard,! in Tonkin, recorded an epizootic among
mules, due, in all probability, to T. evansi.
In recent years surra has been observed in nearly all parts of
French Indo-China (1901-1903), in the Dutch East Indies (since
1899), in the Philippines (1901), in Mauritius (1902), [in Hong Kong-
(1905), and in Perak,^ Federated Malay States (1905)]. The in-
vestigations and experiments made in these different countries have
materially increased our exact knowledge of this deadly epizootic.
As regards India and the countries bordering upon it, Lingard's
last Report (1899) contains detailed information concerning the
geographical distribution of surra, which we shall summarize briefly.
The disease occurs in twenty-two out of thirty-one districts of the
Punjab, in the North-West Provinces, in Kumaon (in the Himalayas),
in the north-east part of the district of Jalpaiguri (Bengal), in Raj-
putana, and in the Bombay Presidency. In other words, nearly the
whole of Northern India is affected, and through Rajputana the
disease reaches as far west as Bombay. The Dekkan is almost
immune. Lingard records an outbreak in 1893 at Secunderabad
(Hyderabad). According to information supplied to us by Drs.
Donovan and Gouzien, the disease is unknown in the neighbourhood
of Madras and of the French possessions in the south-east of India*
(Pondicherry).
Outside India the disease is found in Persia, according to Haig
(quoted by Lingard). It certainly occurs along the shores of the
Persian Gulf, because trypanosomes have been found in horses
imported into Bombay from those parts.
Nearly the whole of British Burmah, Manipur, and Assam are
infected. Steel's original observations having been made at Rangoon
and Taunghu. The same is true of the countries bordering on
China — the Shan Provinces (Lingard) and Yunnan (Blin). We
have no idea of the extent of this epizootic in China, but there are
reasons for thinking that the disease of ponies and cattle recorded by
W. G. Campbell in Korea (quoted by Lingard) is really surra,
although microscopical confirmation is still lacking. [Gibson has
recorded a case of unsuspected trypanosomiasis in a Chinese buffalo,
which was brought to the abattoir in Hong Kong from the neigh-
bourhood of Kowloon (see p. 258).]
In French Indo-China surra is not unknown. Blanchard observed
it amongst the mules imported into Tonkin, and now the disease is
endemic in that region.
^ See MoUereau, Bull. Soc. centrale med. vdter.^ December 30, 1888, p. 694.
^ [Gibsori, Joiirn. Comp. Path, and Therap., v. 18, 1905, pp. 79, 80. |
■* [Leicester, in Report of British Resident-General for the Federated Malay
States, 1905.]
* Donovan has, however, seen trypanosomes resembling T. evansi in a calf
from the neighbourhood of Madras (private communication).
SURRA 249
From information obtained by Blin and Carougeau, veterinary
surgeons at the Pasteur Institute in Nha-Trang(Annam), the regions
most affected are Laos, Upper Tonkin, and Annam (especially in the
neighbourhood of Nha-Trang). Horses and dogs — particularly
European dogs — are affected, and in certain districts this epizootic
is so widespread that horse-rearing is impossible. It is said to be
propagated by horse - flies (?). The experimental investigations
made by Carougeau at Nha-trang,^ and the examination of specimens
of the blood of infected animals (horses and dogs) which he sent us
on two occasions, clearly demonstrate the nature of this epizootic of
Indo-China.
[Recent investigations have shown that trypanosomiasis is
present in practically all provinces of French Indo-China in endemic
form, and that from time to time it becomes epidemic. VassaP has
made an extended study of the trypanosomiasis of horses in Annam,
and has met with epizootics at Nha-trang, Khan-hoa, Vinh, and
other places in Annam. Vassal states that every year there is a
great mortality amongst the horses in the Laos district. Recently
the districts of Vientiane, Muong-Sieng, Luang - Prabang, and
Muong-Sau have been visited by the epizoqtic, which has spread to
the adjacent Siamese provinces. The natives have for a long time
noticed that the horse-flies are always very abundant at the height of
the epizootic. Yersin^ thinks that Laos is an important endemic
focus of the disease. At Yen- Lay, in the province of Ninh-Binh,
Bodin* came across several cases of the disease. Several foci of this
equine epizootic have been met with in Tonkin by Lepinte and by-
Seguin (at Hanoi, Vietri, and Bac-Kan).]
Further south the disease also occurs, for recently a trypanosome
epizootic in horses has been observed at Hatien, a seaport on the
borders of Cochin-China and Cambodia.' [In 1905 Brau, Saint-
Sernin, and Mutin-Boudet^ proved microscopically the presence of
surra in horses in Saigon, which had already been suspected by the
veterinary officers Blin^ and Chaptal.^ It appears that the cases
were always sporadic, coming either from Annam or from a focus at
Cape St. Jacques and environs (Cochin-China).]
The accompanying map (Fig. 29), showing the distribution of
^ Carougeau, Bu/L Soc. centrale mM. vdter., June 30, 1901, p. 295.
2 [J. J. Vassal, Ann. Inst. Past., v. 20, 1906, pp. 256-295.]
^ [Yersin, Bull, econom. de I' Jndo-Ckine, No. 27, 1904, and Ann. Inst. Past.,
1904.]
* [Bodin, Bulletin iconomique. No. 46, October, 1905.]
^ KermoTgant, Bzill. Acad. Me'dedne, v. 50, November 3, 1903, p. 262. Montel,
Ann. dHyg. et de Med. colon., 1904, v. 7, p. 219. The presence of the trypano-
some of surra in the blood of animals suffering from this disease was established
by one of us.
8 [Brau, Saint-Sernin, and Mutin-Boudet, Bull. Chambre d' Agriculture de
Cochinchine, ninth year, February 10, 1906, pp. 39-50. Abstract by Mesnil in Bull.
Inst. Past., V. 4, igo6, p. 674.]
' [Blin, Rev. gen. me'd. v^t., 1903, I., p. 213.]
^ [Chaptol, Rapport au Lieut. -Gouverneur de la Cochinchine, August 8, 1905,
Bull. Chambre d' Agriculture, )>io. 8, August, 1905.]
250 TRYPANOSOMES AND THE TRYPANOSOMIASES
surra in Asia, is borrowed, so far as India is concerned, from the
R.A.M.C. Journal for January, 1904.
In the Dutch East Indies surra was first observed among the
Equidae and buffaloes (var. 'Karboiiw^) of the districts Samarang and
Rembang, in Java. It appears to be spreading, for Schat^ records it
in the interior of Java (in Kediri and Soerabaya), where in igoi an
epizootic attacked cattle and buffaloes. Owing to the energetic
measures taken — the slaughter or isolation of infected animals and
protection against the bites of flies — the outbreak has been checked,
\ c\fcn N \
7 lok \— ,
/o
C^ '"■-•—! '\\s
'(J \ Tinins
Y \
9 ^ 9
Fig. 29. — Map showing the Distribution of Surra in India and Indo-China.
The areas in which the disease is endemic are marked witli a + ; those in which it has
been observed only sporadically or as a temporary epizootic are marked with an O.
and it will doubtless be possible to prevent it from establishing itself
in that region. In Sumatra a spontaneous infection of horses appears
to have been seen by Vrijburg, veterinary officer at Deli.^
[Probably the epizootic of surra in Perak, investigated by
Leicester in 1905, was imported from Sumatra.]
1 Penning, Veeartsenijk. Bladen v. Ned. Indie, v. 12 and 13, 1899 and 1900.
2 Schat, paper published in 1902 in the Archives de V Industrie sucriere ix
Java. We are indebted to M. Van Reuth and Dr. L. Vincent for the translation
of this paper, which is in Dutch.
^ Vrijburg, Veeartsenijk. Bladen v. Ned. Indie., v.
Geneesk. Tijdschr. v. Ned. Indie, v. 41, 1901.
13, quoted by de Does,
SURRA 251
Since September, 1901, surra has been known in the Philippines,
and its presence there induced the Bureau of Animal Industry at
Washington to publish in its Bulletin, No 42 (1902), an ' Emergency
Report on Surra,' by Salmon and Stiles, containing a summary of
the publications on trypanosomes in general, and on surra in par-
ticular. In their work Salmon and Stiles reproduce the reports of
the veterinary oificer Slee, and of Drs. Allen Smith and Kinyoun.
Discovered first among the horses in Manila, it was soon recognised
that the epizootic occurred throughout the island of Luzon. Accord-
ing to Curry, it also attacked buffaloes (var. Kerabau). Musgrave and
Williamson have given a detailed account of the disease in horses.^
They consider that the instances of infection seen by Curry in
buffaloes were exceptional, and that no importance need be attached
to them.
It is by no means certain how the disease originated. Salmon
qnd Stiles incline to a recent importation of the disease. They
think that Anglo-Indian troops carried it from India to China, and
the Americans from China to Luzon. On the other hand, the
medical and veterinary officers who have studied the disease on the
spot are of opinion that the disease existed in the Philippines before
the American occupation, and that it was known there among horses
under the name of Calentura. The report by Maus,^ dated Septem-
ber, 1901, is almost conclusive on this point. He describes what is
evidently the trypanosome of the blood of horses suffering from
calentura under the name of Spirillum, without suspecting that he
had before him a flagellated Protozoon, which was the parasite of a
well-known group of diseases.
In their recent work Musgrave and Williamson state that surra
could not have existed in the Philippines before May, 1901. Their
inquiries lead them to suspect that Australian horses imported the
disease. We may remark here, however, that the presence of surra
in Australia has not yet been proved. Musgrave and Clegg have
published an important work upon the epizootic of surra in the
Philippines.
In Mauritius a trypanosome epizootic amongst horses and cattle
was recorded during 1902, at the beginning of the sugar-growing
season. Already, in June, igo2, according to the veterinary of&cer
Deixonne, the mortality was appalling, the majority of the draught
animals having succumbed.^
^ Musgrave and Williamson, Biolog. Laboratory, 1903, No. 3. Musgrave
and Clegg, ' Trypanosoma and Trypanosomiasis, with Special Reference to Surra
in the Philippine Islands.' Department of the Interior, Biolog. Laboratory, No. 5,
Manila, 1903.
''' Summarized in a leading article in New York Med. Journ., February 8, 1902.
^ On the subject of the epizootic in Mauritius consult : Laveran, Acad, de MM.,
October 28, 1902; Edington's Reports of August 8, 14, and 18, 1902; Report of
the Committee of Inquiry to Study the Steps to be taken to stop the Progress of
the Epizootic in Mauritius, 1903 ; Vassal, ' Sur le Surra de Maurice,' /oa^?/. off. de
Madagascar, June 27, 1903. We have also utilized the information contained in
letters sent to one of us by Dr. A. Lesur and by M. Deixonne, veterinary officer in
Mauritius.
252 TRYPANOSOMES AND THE TRYPANOSOMIASES
Dr. A. Lesur wrote to one of us on June 27, 1902, as follows :
' Surra has been prevalent in Mauritius since the end of last year.
The markets of Madagascar, which have always furnished the colony
with its oxen for transport and for food, having been practically
closed to us on account of the competition of the English military
authorities during the Transvaal War, our traders thought it would
pay them better to import cattle from India. A cargo of them
arrived in September, igoi,but a number of the animals having died
during the voyage, the vessel was put in quarantine. The mortality
continuing, the sanitary authority ordered post-mortems, which,
however, did not reveal the cause of death. Vague and general
explanations were deemed sufficient, and the animals were allowed
to land. Nevertheless, the animals went on dying in the stalls
where they were kept under observation, and the cause of death
remained as obscure as ever. Finally, the animals which survived
were sent to their consignees, who placed them in a district in the
north of the island, where they became a centre of infection, which
gradually spread. At the present time practically the whole of the
island is infected.
' The epizootic at first appeared to be almost exclusively confined
to oxen ; then it attacked mules, donkeys, and horses, without, how-
ever, in any way diminishing its ravages upon cattle. The destruc-
tion of draught animals has gone on lo such an extent that farmers
are anxiously asking themselves whether they will be able to gather
in the harvest. It is true we have already begun to import fresh
animals — healthy ones this time — but as there is no law compelling
the owners of sick animals to slaughter them, we are providing
fresh material which will serve to perpetuate the epizootic.
' The nature of the disease was quite misunderstood at the
outset, which is due to the fact that the veterinary officers in
Mauritius had never seen cases of surra. The diagnosis usually
made was gastro-enteritis, due to bad feeding.
' Last March my brother, Dr. Aime Lesur, at the request of a
friend whose stable was ravaged by the disease, examined the blood
of sick mules microscopically, and found numerous trypanosomes
present. Afterwards he also found them in the blood of cattle.
Some weeks later, when the disease reached the district in which
I live, I had the opportunity of making similar observations. . . .'
Since then the ruin has become complete. On January 29, 1903,
M. Deixonne wrote to us that the horses and mules had practically
all disappeared. At Port Louis it had become necessary to hand
over the work of scavenging to prisoners, who, under the supervision
of policemen, were used to pull the carts.
From July to October, igo2, the death of 1,882 solipedes and
1,681 cattle was recorded in Mauritius (Vassal).
The introduction of the epizootic into Mauritius by cattle from
India has been questioned by Edington, but it is proved that sick
SURRA 253
animals coming from India were imported into Mauritius towards
the end of 1901, and the arguments which have been adduced to
show that surra was endemic in Mauritius before that time are quite
inconclusive. The exceptional severity of the disease in the island
is distinctly in favour of the idea of importation, for epidemic or
epizootic diseases usually spread more rapidly, and are more severe
in districts previously immune than they are in their endemic foci.
In igoi Vassal observed an isolated case of surra in Reunion, in
a cow which was vaccinated against cattle plague by Turner and
Kolle's method in August, 1901, and which died on September 20,
'with very many trypanosomes in its blood, spleen, and kidneys.'^
Although from that time Vassal was always on the look-out for surra,
he never came across another case. The origin of this isolated case
remains a mystery, because the cow. Dr. Vassal told us, was born at
St. Denis, in Reunion.
M. Deixonne was good enough to send us, through Dr. Vassal,
living trypanosomes from animals with the Mauritian epizootic. We
have consequently been able to study the disease in other animals.
The epizootic in Mauritius, after a period of quiescence during
the last six months of 1903, showed a marked renewal of activity in
February, 1904.^
[Further information concerning the Mauritian epizootic is given by
Edington and Coutts^ and by Manders.* Edington states in his report
(p. 59) that during the year 1903 information had been received from
Mauritius to the effect that some of the diseased animals had completely
recovered, and were doing good work ; also that two oxen inoculated by
him shortly after his return from Mauritius had completely recovered
from the disease. Their blood was no longer infective, and the oxen
were completely immune, ' as esven after a large inoculation into the vein
the blood is not found to be infective when tested by inoculation into
susceptible animals.'J
[Manders states that the greatest mortality occurs during the months
when Stotnoxys genicttlatus, De Bogot — the almost certain carrier of the
disease in Mauritius — is most abundant. The local authorities now order
the killing of any horse, ass, or mule certified by a veterinary surgeon to
have surra, but cattle as a rule are isolated. In 1904, 283 solipedes and
24 bovines were slaughtered by order of the Medical and Health Depart-
ment. Between January and April, 1905, 228 solipedes were slaughtered,
but no bovines.]
[The latest accounts ^ of the Mauritian epizootic show that cattle are
quite as susceptible as horses and mules. In 1903, 2,251 cattle and
965 solipedes died of the disease ; in 1904, 260 cattle and 823 solipedes.]
' Vassal, Revue agricole de la Reunion, December, igoi.
2 Letter from M. Deixonne, dated Mauritius, February 11, 1904.
' [A. Edington and J. iVI. Coutts, Report of the Director of the Government
Bacteriological Institute, Grahamstown, for the year 1903, pp. 58-61. Cape Town,
I904-]
4 [N. Manders, R.A.M.C. Journ., v. 5, 1905, pp. 623-626].
'' [Annual Report of the Medical and Health Department for 1904, Port Louis,
June 29, 1905, quoted from Vassal.]
254 TRYPANOSOMES AND THE TRYPANOSOMIASES
Sebtion 2.— Animals Susceptible to Surra. Symptoms and
Course of the Disease in Horses, Cattle, Dogs, etc.
Like nagana, surra is inoculable into most mammals,^ but the
disease occurs naturally only in the Equidse, Bovidae, Camelidas, and,
more rarely, in dogs. We shall first study the symptoms and course
of the disease in these animals, and afterwards consider the animal
species in which surra is known only as an experimental disease.
Equid^. — The horse, mule, and donkey are very susceptible to
surra. In certain parts of India surra frequently gives rise to serious
epizootics amongst horses. In 1890 forty ponies died of the disease
at Katgodam, while fifty more died from 1891 to 1893. In 1893
-/OS"
-I01-'
103'
-101.'
-lot'
-100'
99'
- 98*
-97°
Fig. 30. — Temperature Chart of a Horse which died of Surra during the
Epizootic in Mauritius.
[The normal temperature of the horse varies from 98-4° to 102° F (37° to 39° C. ).]
there was an outbreak in the stables between Saharanpore and
Mussoorie. There have been several outbreaks of surra among the
horses in Sind.
The first symptom of the natural disease is a rise of temperature.
After experimental inoculation, either subcutaneous or intravenous,
Lingard found that the incubation period varies from four to
thirteen days. In a certain number of cases the rise of temperature
is soon followed by an urticarial eruption. Petechial haemorrhages
on the mucous surfaces — particularly of the nictitating membrane —
running from the eyes, and oedema also occur. The animal is
dejected and shows marked loss of strength, but, as a rule, the
appetite is good. The mucous membranes become very pale, and
later on yellowish in colour. Anaemia is constant and progressive ;
there is an increase in the number of the leucocytes except of the
1 The disease does not appear to be transmissible to man. Schat pricked him-
self several times, with impunity, with needles which had been used to draw blood
from animals infected with surra. Birds are refractory (Lingard, Penning).
Mai
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Fig. 31. — Temperature Chart of a Horse which died of Surra during the
Mauritian Epizootic.
In a letter dated June 27, 1902, Dr. Alfred Lesur describes the
symptoms observed in Equidae during the epizootic in Mauritius in
the following words :
' The onset of the disease is insidious. The first noticeable
symptom is a change in the gait. The animal no longer exhibits
its customary vigour, but is slow at its work and appears to be lazy.
This is often accompanied by a loss of appetite, but this is not a
constant symptom.
' Fever soon makes its appearance, the temperature often rising
to 41° C. [106° F.], or even higher. A certain number of animals
die at this stage, but they are the minority. In the others the
temperature, after oscillating at this high level for two or three days,
falls spontaneously, or as the result of treatment. Fresh rises of
temperature occur at intervals of four, five, nine, or ten days.
' Shortly after the onset of fever large cedematous swellings
SURRA 257
appear on the chest, hypogastrium, and in the male very often in
the sheath. On incising these swellings a small quantity of fluid
escapes, in which many trypanosomes are found. These swellings
may disappear and reappear again during the course of the disease.
' Anaemia rapidly supervenes and becomes very profound. The
conjunctivae are exsanguine, and the buccal mucous membrane has
an ivory-white colour.
' At this stage of the disease the animal has lost its appetite, is
very feeble, and easily falls in its stable, often never to rise again.
' Death may occur very suddenly in the first stage of the disease ;
and, indeed, many animals which were not apparently ill, and which
were still working, died in this way.
' Trypanosomes in appreciable numbers are present only for a
short time and intermittently in the peripheral blood. For example,
an animal which showed many parasites in its blood on a Tuesday
did not show a single one on the following Saturday. This disap-
pearance of the parasites, which may be only apparent, does not
coincide with any improvement in the animal's condition.' ^
Dr. Lesur kindly sent us temperature charts (Figs. 30 and 31
are reproductions of two of them) which show the characteristic
rises of temperature occurring in surra.
BoviDiE, Buffaloes. — Bovines are much more resistant than
equines. Lingard infected oxen by inoculating them with blood,
but they all survived and had very few symptoms. There is swelling
at the site of inoculation. As a rule, the temperature rises at the
onset of the infection, and from time to time other rises may occur.
The parasites are visible in the blood only from the fourth to the
tenth day after inoculation, rarely later. But the blood remains
infective for the guinea-pig for a very long time. In one case it was
infective 163 days after inoculation, but was no longer so on the
234th day. The animal recovers after having wasted very con-
siderably. These observations of Lingard have been confirmed by
Rogers. A second inoculation is not followed by any symptoms ;,
in one case a single trypanosome (giant form) was seen under the
microscope six days later. Subsequent inoculations into guinea-pigs
were negative ; the animal, therefore, had become immunized -by
recovering from the first attack of the disease.
Vrijburg, in Sumatra, has confirmed this observation in the case
of the zebu.
Steel regards the ox as refractory simply from the microscopical
examination of the blood ; nevertheless, the ox inoculated by him
showed rises of temperature, the first of which was particularly
marked a few days after inoculation.
Lingard has studied the disease as it occurs naturally among oxen
in India. Recovery is the rule, but the animals pass through a stage
1 Private communication from Dr. A. Lesur ; see Laveran, Acad, de Mdd.^
October 28, 1902.
17
258 TRYPANOSOMES AND THE TRYPANOSOMIASES
of extreme emaciation. The blood is rich in trypanosomes during
the febrile paroxysms.
Lingard has demonstrated the relatively great susceptibility of
the buffalo. In two buffaloes the incubation period was five days.
One animal died in 125 days, after twelve febrile paroxysms, with
marked emaciation, in spite of a voracious appetite right to the end ;
the second buffalo died in 51 days.
[Two buffaloes inoculated by Pease with the camel trypanosome
died, very wasted, in 120 and 46 days ; a third was alive more than
two years after infection, but its blood was still infective on inocu-
lation into dogs. Pease found that the camel trypanosome, which at
first killed dogs in from 63 to 288 days, became more virulent for
dogs (killing them in 52 to 99 days) after passage through the
buffalo. He is of opinion that in India the buffalo plays an important
part in the transmission of surra.]
Penning (loc. cit, second paper) has described in detail the out-
breaks of surra among the buffaloes at Samarang and Rembang
(Java). The disease usually runs a chronic course, but in some
cases death occurs suddenly. The usual symptoms are gradual
wasting, small oscillations of temperature, and muco-purulent in-
flammation of the cornea, eyelids, and nose. Some animals also
have cedematous swellings, especially of the abdomen.
[In Hong Kong, Gibson^ found numerous trypanosomes in a
blood-film of a Chinese buffalo, which died suddenly in the abattoir
into which it had been brought the previous day apparently in good
health. These small buffaloes, which are slaughtered for food, are
brought to Hong Kong from the mainland of China, twenty or thirty
miles from Kowloon.^]
[Shortly afterwards trypanosomes were found in a sick dog
belonging to the inspector of the abattoir. These trypanosomes
were pathogenic for dogs and guinea-pigs, but none of the latter
died. According to Gibson, the trypanosome is morphologically
indistinguishable from T. evansi.']
During the epizootic in Mauritius the mortality amongst cattle
was rarely more than 25 to 30 per cent., whilst in equines it was
100 per cent. (Deixonne). Animals which are well nourished and
which are not made to do hard work live much longer than those
which are badly nourished and overworked. In Mauritius the
animals kept solely for breeding purposes enjoyed almost complete
immunity from the disease, whereas in certain districts the mortahty
amongst cattle made to do hard work was from 75 to 80 per cent. Over-
worked oxen when they become infected die of anaemia rather than of
surra, for the injection of their blood in the last stage of the disease
into susceptible animals often gives negative results (Deixonne),
1 [Gibson, /ourn. Comp. Path, and Therap., v. 18, 1905, p. 79.]
2 [Personal communication from Dr. Bell, of the Government Civil Hospital,
Hong Kong.]
SURRA 259
In Mauritius the symptoms of surra in cattle were as a rule much
less constant and less marked than in equines. Frequently the only
sign of the disease was the periodical febrile paroxysm, which passed
unnoticed if the animals' temperatures were not taken.
Trypanosomes are scanty in the blood, and as a rule they are not
seen on microscopical examination, so that it is necessary to inoculate
susceptible animals in order to make certain of the diagnosis.
Sometimes, however, the disease in cattle may be very grave and
run a very rapid course. During the epizootic in Java these grave
forms, accompanied by complications, were particularly frequent.
The following summary is from Dr. Schat's account of the epizootic :
The respiration and pulse rates are greatly accelerated, the tempera-
ture rises to 40° or 40-5° C. [104° to 105° F.], the nostrils are dry,
and the eyes watery, with intense redness of the conjunctivae. There
is a pustular eruption, with the formation of scabs and small super-
ficial abscesses in different parts of the body, particularly on the
neck, belly, and hind-legs. The buccal mucous membrane is covered
with red patches, and the animal loses its appetite. There is almost
constant diarrhoea, the dejecta consisting of reddish matter mixed
with undigested food. In less severe cases the excreta are greenish-
yellow in colour, without any trace of blood.
In one ox there was actual sweating of blood : minute droplets
of blood were seen rising up on the surface of the skin, without
any traces of pricking or stinging by insects. In other cattle there
were haemorrhages from the nostrils and ears, or an abundant
discharge of greenish fluid from the nose.
In the severe infections the animals died in twenty-four hours
after the first appearance of symptoms^ ; in other cases the disease was
prolonged for three or four weeks, and it might then end in recovery.
The oxen known as Madoereesche were less often attacked than the
pure-bred Javanese oxen, and when they were attacked by the
disease they were more resistant than the latter.
Trypanosomes have been found in apparently healthy animals,
so that the disease may exist in a latent form. Schat sometimes
found numerous trypanosomes in the blood of cattle. In the paper
by Musgrave and Clegg previously mentioned there are interesting
details of the course of surra in cattle during the outbreak in the
Philippines. One ox died in twenty-four days.
Several bovines were inoculated with surra by Nocard and
Vallee at Alfort, one of the animals dying of the disease. Fig. 32
gives the course of the temperature in a calf which was inoculated
with surra on July 4, 1903, by Valine. The animal never showed
any symptoms, but in February, 1904, its blood was still virulent,
and the calf was still alive in May, 1904.
1 This does not mean that the trypanosome of surra can kill cattle in twenty-
four hours, or even in several days, but that the, disease which has been latent
may suddenly manifest itself by rapidly fatal symptoms.
17—2
26o TRYPANOSOMES AND THE TRYPANOSOMIASES
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animals at Alfort, state that at the end of a year trypanosomes could no
longer be found in the blood ; and the two animals (Breton calves) were
^ [Laveran and Mesnil, C. R. Acad. Sciences, v. 140, 1905, p. 831 ; see note by
Vallee and Panisset on p. 833.]
SURRA 261
reinoculated with the same virus on July ig, 1904. No infection followed,
thus showing that the calves had acquired immunity against Mauritian
surra. Two inoculations with the virus of mbori, made on August 8 and
September 19, 1904, were equally unsuccessful.]^
[On December 15, 1904, the two calves were inoculated with the
Indian strain of surra, and at the same time a normal Breton cow was
inoculated as a control. Blood taken on December 23 and 30 from the
control cow was infective for mice and guinea-pigs in very small doses,
whereas that of the two calves was not infective, even in large doses. On
January 18, 1905, 100 c.c. of blood were taken from each calf, and 50 c.c.
injected at once intraperitoneally into dogs. All four animals so injected
were still free from trypanosomes two months later. The control cow had
a severe infection, to which she nearly succumbed, and her blood was still
infective in March, 1905.]
['This experiment establishes indisputably the identity of Indian and
Mauritian surra ' (Vallee and Panisset).]
[An ox was inoculated by Edington and Coutts with the Mauritian
virus on September 4, 1902. Between that date and November 2, 1903,
it received seven other injections of virulent blood. The ox had become
immunized. Rats inoculated with blood of this ox on November 3 and 5,
1903, did not become infected, whereas some months previously the blood
of the ox produced a fatal infection in dogs.]
Camels. — According to Lingard, the symptoms of the spon-
taneous disease in camels are : fever, swellings — of the chest, of the
sheath, and scrotum in males, and of the breasts in females — which
may suppurate and contain much pus, and progressive anaemia and
wasting, in spite of a good appetite. The trypanosome is found in
the blood only during the febrile paroxysms, when the temperature
may be as high as 41° C. [io5'8° F.]. There would appear to be a
small percentage of recoveries when the disease has lasted more than
three years.
Elephants. — The occurrence of surra in elephants in India
and Burmah is practically proved. In this connection we have only
the statement of G. H. Evans, reproduced by Lingard (Summary of
Further Report, 1894), that in 1893 fourteen out of thirty-two
elephants died of the disease in Burmah. In his Annual Report for
1895-1896 Lingard incidentally mentions the trypanosomes of the
elephant, as if he had seen them. It is, however, doubtful whether
the elephant is to be included in the category of animals in which
surra runs an invariably fatal course.
Dogs. — Surra has often been seen as a natural disease in the dog.
Lingard records, in his various reports, the occurrence of epizootics
of surra among sporting dogs introduced from England. He
observed outbreaks in the island of Bombay, and in other parts of
the Bombay Presidency. He quotes the opinion of Evans that surra
occurs among the dogs at Mandalay, and that of H. T. Pease, that
it occurs among the dogs in the district of Karnal, in the Punjab.
In 1891 a disease which appears to have been allied to surra was
* [Valine and Panisset, C. R. Acad. Sciences, v. 139, 1904, p. 901.]
262 TRYPANOSOMES AND THE TRYPANOSOMIASES
prevalent among several packs of hounds in Bombay. In 1893
Lingard^ saw an outbreak of surra among English foxhounds.
The following are the principal symptoms noted : Elevations of
temperature, anorexia, oedema of the head and throat, injection of
the conjunctivas, and, in some cases, effusion into the joints, and
corneal opacity leading to partial or total blindness. Huring the
febrile paroxysms trypanosomes are found in the blood on micro-
scopical examination.
We have already mentioned that spontaneous cases of surra in dogs
have been reported in Indo-China [and Hong Kong^]. During the
epidemic in Mauritius a certain number of dogs died of surra. We
shall refer to this again later. It seems that the mode of infection in
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Fig. 33. — Temperature Chart of Dog No. 4, inoculated Intravenously with
Surra.
O means absence of trypanosomes on microscopical examination +, trypanosomes
present, but scanty ; + + , fairly numerous ; , numerous or very numerous ;
T r
>J", means death.
dogs is not the same as in horses and cattle, which would account
for the relative rarity of the disease in dogs.
Dogs are easily infected with surra by subcutaneous inoculation.
Lingard experimentally infected eight dogs, which died in 145^, 21,
27I, 29, 34, 36, 47, and 97 days after inoculation with blood obtained
from different animals. The dog which lived 97 days — the incubation
period lasting only 5 days — had been inoculated with the blood of
a bovine suffering from the natural disease. In all cases the experi-
mentally produced disease showed the same symptoms as the natural
disease.
*• Lingard, Report of 1894. According to Lingard, surra had been prevalent in
dogs ever since 1869 in the kennels at Ootacamund, and in 1884 fourteen couples
of dogs died in the packs in Madras of the same disease, the true nature of which
was, misunderstood until 1893.
2 [Dr. Bell, of the Government Civil Hospital in Hong Kong, has sent home
blood-films from a guinea-pig inoculated with the blood of a sick dog, in' which I
have found many trypanosomes closely resembling the parasite of surra. Professor
Laveran, to whom I sent one of the slides, writes that he is also of opinion that
' these trypanosomes are very much like those of surra.' — Ed.]
SURRA
263
In dogs subcutaneously inoculated trypanosomes appear in the
blood from five to seven days after inoculation. There is a rise of
temperature at the same time, and these febrile attacks are repeated
from time to time during the progress of the disease (see charts,
Figs. 33 and 34). The number of trypanosomes in the blood also
varies. At times they are scanty, but these periods of arrest or of
diminution in the multiplication of the parasites are short. During
the last days of the disease trypanosomes are very numerous in the
blood, but their diminished activity points to the approach of death.
Surra is always fatal in dogs, the average duration of the disease
being, in our experiments, twenty-eight days. Below we give the
details of the observations on two dogs inoculated with surra — the
first intravenously, the second subcutaneously.
Dog No. 4.— Weight, 11 kilogrammes. On October 20, 1903, i c.c. of
diluted blood of an infected mouse was inj acted subcutaneously. Tempera-
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Surra on October 20, 1903 ; died on November 19, 1903.
The symbols O, +, etc., have the same significance as in Fig. 33.
ture before inoculation was 39° C. [102-2° F.]. On October 23 a few para-
sites were seen in the blood, and at the same time there was a considerable
rise of temperature — to 41-4° C. [io6-6° F.]. From October 24 to 30 fever
continued with slight remissions. Trypanosomes rapidly increased in
number from the 23rd to 25th, and then remained almost stationary until
the 31st. On October 31 and November i and 2 the temperature fell to
between 39'8° and 39-4° C. [103-6° and 103° F.], but the trypanosomes ,
became very numerous. On November 3 and 4 the temperature rose
again to 41 -4° C. [io6-6° F.], while the trypanosomes became less numerous,
and even scanty on November 4. On the 5th there was a considerable
fall of temperature, but a fresh rise occurred on the 6th. After this the
temperature gradually fell, so that on November n it was only 37-8° C.
[100° F.]. From November 7 till the night of the i ith and 12th, when the
dog died, the parasites were very numerous in the blood. There was
marked wasting, and at death the animal weighed only 9-8 kilogrammes.
The spleen was much enlarged, its weight being 210 grammes — about
ten times the normal weight. There were never any eye symptoms
or oedematous swellings, i ■ •
264 TRYPANOSOMES AND THE TRYPANOSOMIASES
Dog No. 5. — Weight, i2| kilogrammes. This dog was also injected on
October 20, 1903, with i c.c. of diluted blood from a mouse, but subcuta-
neously. On that day the temperature was 39-8° C. [103-6° F.], and although
it rose to 40-1° C. [104-2° F.] on the 23rd, the blood examination was nega-
tive. Trypanosomes were very scanty on the 24th, and gradually increased
in number. From the 28th onwards there was intermittent or remittent
fever. On November 18, the day preceding death, the temperature was
40-3° C. [104-6° F.]. Trypanosomes were present in the blood every day,
their relative abundance being indicated on the chart (Fig. 34). The animal
showed no eye symptoms or swellings in any part of the body. It died
on November 19, the weight being 12-2 kilogrammes. The spleen weighed
170 grammes — about five times the normal weight. There was nothing
else abnormal at the post-mortem examination.
[Eight dogs were inoculated by Edington and Coutts^ with the
Mauritian trypanosome. The disease lasted on an average 23'6
days (minimum 13 days, maximum 39 days)] .
[Thomas and Breinl, also with the Mauritian trypanosome, found
the incubation period, after subcutaneous inoculation, to be seven to
nine days, and the total duration of the disease sixteen to thirty days.
At first the trypanosomes were scanty in the blood ; they remained
scanty till four or six days before death, or there were marked
exacerbations persisting for a few days. In the early stages the
animals presented very few symptoms, but with the rapid multiplica-
tion of the parasite decided anaemia and emaciation occurred.
Death was usually preceded by a subnormal temperature. Post-
mortem the usual lesions met with in dogs dying of acute trypano-
somiasis were found.]
[Laveran and Mesnil,^ during a series of experiments carried
out with the Indian surra trypanosome^ in order to compare its
effects upon animals with those of the Mauritian trypanosome,
inoculated two dogs. They died in twelve and thirteen days, the
incubation period lasting three days. There was continued fever,
the temperature remaining at 39° or 40° C. [i02'2° to 104° P.], and
even exceeding 40° C, until death. Trypanosomes were abundant
in the blood, with a period of diminution about the middle of the
disease. There were no external lesions, but wasting was extreme,
the weight of the second dog falling from 7 to 4*8 kilogrammes.
The spleen was enlarged, weighing 60 grammes in a dog of
7 kilogrammes.]
[Pease* inoculated three pariah dogs with Indian surra — an equine
virus passed through a rabbit — after having unsuccessfully inoculated
them with dourine. The dogs died in 35, 22, and 20 days respectively,
after inoculation with the T. evansi.]
Surra not only occurs naturally in several animal species, but its
' [Edington and Coutts, op. ci/., p. 59.]
^ [Laveran and Mesnil, C. R. Acad. Sciences, v. 140, 1905, p. 831.]
^ This strain of trypanosome was obtained from a camel by Lingard, who gave
it to Dr. C. J. Martin, Director of the Lister Institute. The authors express their
indebtedness to Dr. Martin for sending them an infected mouse.]
* [Pease, Veiermary Journal, v. 9, 1904, p. 187.]
SURRA . 265
trypanosome is pathogenic for a number of other mammals. We
shall consider these animals in the order of their susceptibility,
beginning with the most susceptible.
Mice. — The parasites appear in the blood on an average on the
fourth day after intraperitoneal, and on the fifth day after sub- ■
cutaneous, inoculation. From the time that they occur in the blood
they gradually increase in number, so that during the last few days
of the disease they may be as numerous as the red corpuscles.
Their activity becomes much diminished during the few hours
immediately preceding the death of the infected mice.
The disease, if untreated, always ends fatally. During the last
few days the animal loses its usual liveliness and remains very quiet
and huddled up. Its coat usually becomes rough and bristling.
The average duration of the disease after subcutaneous inoculation
is eleven and a half days.
In several mice inoculated with the blood of a goat or dog with
surra the disease ran an abnormal course. The parasites, after
being present in the blood, diminished in number, or even dis-
appeared on microscopical examination. They soon reappeared,
however, and multiplied until the time of death. The disease lasted
from fourteen to sixteen days, and in one case twenty-four days. It
is rather curious that when three mice are inoculated under
apparently identical conditions, surra may run an abnormal course
in one and a normal course in the other two. The blood of a goat
or sheep infected with surra usually contains very few trypanosomes,
which partly accounts for the abnormal course of the disease in
mice inoculated with blood from that source.
[Thornas and Breinl, using white and grey mice, found the
incubation period to be three to four days, and the total duration
nine to twelve days. Mice and rats inoculated with attenuated
trypanosomes, such as are present in the blood of animals under-
going treatment, may only show a few parasites in their blood.
Such rats and mice often acquire a chronic form of the disease,
from which they frequently recover, but they are not immunized.]
[Experimenting with the Indian virus, Laveran and Mesnil found
that at first the incubation period was 9 days, and the total
duration i8|- days. After passage through a rat or mouse, the
virus was exalted for the mouse, which, inoculated subcutaneously,
died in ^j to 8 4 days (average 6 days), with incubation period of
2 to 4 days, and inoculated intraperitoneally died in 2 J to 3^ days,
with incubation period less than i day. A grey wild mouse,
inoculated subcutaneously, died in 7J days ; incubation period
4 days. Except in the case of a few mice which were inoculated
with guinea-pig's blood, the trypanosomes never diminished in
number, and at death were at least as numerous as the red corpuscles.
The spleen was enlarged, and generally weighed i gramme in a
mouse of 20 grammes.]
266 TRYPANOSOMES AND THE TRYPANOSOMIASES
[A jerboa (Jaculus orientalis) inoculated by Laveran^ with the
Mauritian virus died in five days with an acute infection. It was,
therefore, more susceptible than the rat to this virus.]
[Bat. — It has already been mentioned (p. 109) that Laveran
inoculated a bat with the Mauritian trypanosome, and that the bat
died, severely infected, nine days after inoculation.]
Rats. — The trypanosomes of surra appear in the blood of white
rats on the fifth or sixth day after subcutaneous inoculation.
They rapidly increase in number, and are always very numerous at
the time of death. The disease is invariably fatal, the average
duration being eleven days. In the last stages the animals are
obviously ill ; they lie huddled up, and the coat is rough. We have
never seen rats die suddenly with convulsive seizures, as with
nagana.
[Edington and Coutts inoculated, with the Mauritian trypano-
some, three white rats, which died in 4, g, and 15 days. Thomas
and Breinl found the incubation period to be 3 to 4^ days after
subcutaneous, 2f to 3^ days after intraperitoneal injection. The
average duration of the disease was 5 to 7 days after the appearance
of the trypanosomes in the peripheral blood. The course of the
disease in their rats (white, black, and grey) was similar to that seen
in mice.]
[Laveran and Mesnil inoculated four rats with the Indian
trypanosome, two subcutaneously and two intraperitoneally. In the
former the incubation period was 3 and 3J days, and death occurred
in 5 J and 6j days ; in the latter the incubation period was less than
24 hours, and death occurred in 3^ and 4 days.]
Monkeys. — Steel showed that the monkey is susceptible to
surra. He inoculated a monkey of the ' ordinary Burmese variety,'
probably a Macacus, subcutaneously with a sj'ringeful of blood. The
monkey showed trypanosomes in its blood on the third day after
inoculation — not on the fifth to the ninth day, but after that the
parasites were again present. On the evening of the second day
there was a rise of temperature, and later there were many such
febrile attacks. The temperature chart given by Steel is very
interesting, but refers only to the first month. One of the earliest
symptoms was a reddish discharge from the vulva. The monkey
became very weak and looked dejected. After two months there
was great weakness of the limbs, also swelling of the feet going on
to ulceration, which extended down to the bones. Finally the upper
eyelids became cedematous, and the animal died after some hours
of coma and slight delirium.
Carougeau, Musgrave, Williamson and Clegg {loc. cit.) have also
shown the susceptibility of the monkey to surra.
Rabbits. — The susceptibility of the rabbit to surra has been
shown by Lingard, Carougeau, and Penning, the laist- named observer
^ [Laveran, C. R. Soc. Biol., v. 59, 1905, p. 250.] '
SURRA 267
noting that rabbits with surra often show the same symptoms as
rabbits with dourine.
Unlike mice and rats, rabbits never show many trypanosomes in
their blood. At the beginning of the disease the animals eat well
and put on flesh; towards the end, however, they rapidly lose
weight. For example, a rabbit weighing 2,270 grammes was inocu-
lated by us with surra on May 22, 1903 ; on June 14 it did not
appear ill, and its weight was 2,420 grammes, and trypanosomes
were very scanty in its blood. It died on June 25, its weight being
1)^95 grammes. Throughout the disease the parasites were very
scanty in the blood.
At the onset of the infection, when trypanosomes first appear in
the blood, there is often a slight rise of temperature. The disease
lasts on an average one month, and always ends fatally.
[Edington and Coutts inoculated eight rabbits with the Mauritian
virus. The average duration of the disease was thirty-five days
(minimum two days (?), maximum fifty-nine days).]
[Thomas and Breinl found the incubation period to be three and a half
to five and a half days after intravenous inoculation. The appearance of
the parasites in the peripheral blood was usually accompanied by a slight
rise of temperature, but with a severe infection the initial temperature
sometimes rose to 106° or 107° F. (41° to 41-6° C). During the course of
the disease the fever was sometimes marked and of an irregular type ;
in other cases there was hardly any rise of temperature throughout.
Trypanosomes were usually scanty in the blood, but in a few cases they
were present in large numbers — ten to forty in a field. The temperature
usually became subnormal before death ; the trypanosomes were then
almost absent, but in some cases were largely increased in number.]
[The symptoms were similar to those seen in rabbits with nagana and
caderas. CEdema of the ears and perineum, sweUing of the testicles or
vulva, and discharges from the penis, eyes, and nose, may all be more or
less marked. Anaemia may be present, and loss of weight is constant.
Young rabbits were found easier to infect than adults.]
[Two rabbits inoculated — the one subcutaneously, the other
intraperitoneally — with the Indian trypanosome by Laveran and
Mesnil died in twenty-seven to twenty-eight days, very wasted, but
with no external lesion. Trypanosomes were very rarely seen in
the blood, except during the last four or five days of the infection ;
but the blood was, nevertheless, infective for mice in very small
doses.]
GuiNEA-PiGS. — In guinea-pigs inoculated subcutaneously try-
panosomes appear in the blood on the sixth or seventh day after
inoculation, sometimes a little later. At the same time there is a
slight rise of temperature. Thus it rose from 39° C. [io2"2° F.] — the
normal temperature of the guinea-pig — to 40"3° C. [i04'6° F.] in one
case, and to 40'2° C. [i04"4° F.] in another, the rise of temperature
in each case being only of short duration and not recurring. The
anirrials eat well and continue to gain weight — at least, during the
268 TRYPANOSOMES AND THE TRYPANOSOMIASES
early part of the disease, but in the later stages they waste. For
example, a guinea-pig weighing 700 grammes was inoculated with
surra on May 22, 1903. On June 14 its weight was 830 grammes,
and the animal appeared well, although trypanosomes were fairly
numerous in its blood. The animal died on June 30, its weight
being only 670 grammes.
The increase in the number of trypanosomes in the blood is not
steadily progressive, as in the case of mice and rats, but takes place
irregularly. During the exacerbations the trypanosomes are
numerous, whereas in the intervals between them the parasites are
scanty, and may even be absent on microscopical examination. At
death they are often scanty in the blood.
The disease is always fatal, and in our experiments lasted on an
average 80 days (maximum 104, minimum 39).
As guinea-pigs are easily obtainable, and live a long time with
the disease, they are used to keep this trypanosome alive in labora-
tories. By inoculating a guinea-pig every month, the virus can be
kept going indefinitely.
[Edington and Coutts inoculated seven guinea-pigs with the
Mauritian trypanosome. The first four died in 66, 49, 59, and
51 days; the last three died in 10, 30, and 10 days; the average
duration was 39 days.]
[Thomas and Breinl found the incubation period to be six to
eight days, and the total duration forty days to four months.
Trypanosomes were scanty in the blood at first, but increased later.
At times they almost disappeared, then became more numerous
again. There was usually a rise of temperature when the trypano-
somes first appeared in the blood, but subsequently the temperature
was never very high. Anaemia was not marked, but there was loss
of weight, especially when many trypanosomes were present for
some time. CEdema was observed in a few cases. No animal
recovered without treatment.]
[Laveran and Mesnil's first four guinea-pigs, inoculated with the
Indian virus, died in 76 to 88 days (average 80 days). The later
ones, after passage of the virus through guinea-pigs, died sooner —
in 20 to 77 days. The average duration in the case of all thirteen
guinea-pigs was 57 days. After an incubation period of several
days, trypanosomes appeared in the blood, and remained present in
variable, but often considerable, numbers until death. There were
no external lesions.]
[Cats. — Thomas and Breinl infected cats with the Mauritian
virus. After intraperitoneal injection the incubation period was
eight to twelve days. The infection was usually chronic, lasting
for six and a half to eight months, but in kittens the disease was
more acute, often lasting only four to six weeks. In adult cats the
symptoms were not very pronounced : slight anasmia and loss of
weight, which increased towards the end of life ; a discharge from
SURRA 269
the eyes and nose, and oedema of the perineum were occasionally
observed. Trypanosomes were usually scanty in the blood of adult
cats, but were numerous in the case of kittens. The chronic cases
showed no characteristic lesions post-mortem, but in kittens the
spleen and lymphatic glands were enlarged.]
[Panisset,^ at Alfort, inoculated the same trypanosome into cats.
He found the incubation period to last, on an average, four days,
and the total duration twenty-one days (maximum fifty-one days,
minimum nine days). Wasting was usually marked, and, in the sub-
acute cases cfidemas, paresis, and ocular troubles were observed.
As a rule the parasites were very numerous in the blood. Passages
through cats did not produce any alteration in the virulence of this
trypanosome.]
Goats. — Steel looks upon the goat as refractory ; nevertheless, the
goat he inoculated had a rise of temperature to 4i;5° C. [io6'8° F.]
on the ninth day after inoculation, and was markedly emaciated at
the end of a month. Penning also considers the goat refractory.
Two goats inoculated by Lingard died of surra. In both cases
the incubation period was six days, then the temperature went up —
in one goat to 42'2° C. [108° F.] — and trypanosomes appeared in the
blood. The first goat had remittent fever, and died on the fifty-
third day of the disease. The second goat also had remittent fever,
and showed trypanosomes in its blood for a fortnight, after which
they disappeared. The animal died at the end of four and a half
months.
We have performed several experiments upon goats. Five or six
days after inoculation with surra, the temperature goes up to 40° C.
[104° F.], and then comes down again to normal. Sometimes there
is a second rise a few days later. Except for these febrile attacks,
which would pass unnoticed if the animal's temperature were not
taken regularly, surra produces no symptoms in goats ; the animals
do not waste, and there are- no oedematous swellings. The trypano-
somes are always so scanty in the blood that they are not seen on
microscopical examination, but inoculation into rats or mice is
necessary to ascertain whether the animals are infected or not.
After lasting about five months the disease usually ends in
recovery. Goats which have recovered are immunized against
surra.
[Edington and Coutts inoculated five goats with the Mauritian
trypanosome. These animals lived 96, 55, 43, 33, and 52 days, the
average being 56 days.]
[An old goat was inoculated by Pease with the trypanosome of
Tibarsa surra (camel) ; it became infected and died in 209 days.] •
tA goat ( $ ), weighing 31 kilogrammes, was inoculated subcutaneously
^averan and Mesnil with i c.c. of guinea-pig's blood containing the
' [Panisset, C. R. Soc. Biol., v. 58, 1905, p. 15 ; abstract by Mesnil, Bull. Inst-
Past., V. 3, 1905, p. 260.]
270 TRYPANOSOMES AND THE TRYPANOSOMIASES
Indian virus. Trypanosomes were found in the blood of the goat on the
fourth, fifth, sixth, and ninth days after injection, but they were not seen
afterwards, although the blood was examined daily for nearly a month. The
blood was, nevertheless, highly infective on inoculation into mice. There
was a marked febrile reaction from the fifth day onwards, and for a month
the temperature rarely fell below 40° C. [104° F.] ; on several occasions it
rose to 41° C. [105-8° F.], and once even to 41-5° C. [io6-8° F.]. Five
weeks after injection the temperature fell to 39° C. [102-2° F.], and the
animal was in good condition.]
Sheep. — A ram was inoculated by Lingard on two occasions, with
an interval of fourteen days between them. On the sixth day after
the second inoculation the temperature rose to 41*9° C. [107-4° F.]
Trypanosomes were never found in the blood on microscopical
examination, but eighteen days after the second inoculation the
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Surra on October 13, 1903.
Trypanosomes were present in the blood on October 26 and November 2, 1903. At the
end of three months the sheep's blood was still infective.
blood was infective for a guinea-pig. On the twenty-eighth day
after inoculation there was fluid in the tunica vaginalis testis, and
on the forty-fifth day trypanosomes were found in this fluid. On
the 104th day the animal had paresis of the left side of the body,
and it died on the 127th day.
In European sheep surra runs practically the same course as it
does in goats. The only symptom is a rise of temperature to 40° or
41° C. [104° or 105-8° P.], which may occur on several occasions.
(See chart, Fig. 35). The animals take their food well, and often
put on weight during the course of the disease. As a rule trypano-
somes are very scanty in the blood, but they are occasionally seen
on microscopical examination.
As with goats, the disease may end in recovery after a dura-
tion of five to six months, and animals which have recovered are
immune.
SURRA 271
[Birds. — Edington and Coutts injected a pigeon, but unsuccessfully,
with the Mauritian virus. Two geese injected by Mesnil and Martin with
the Indian virus also failed to become infected. The birds remained in
good health ; their blood never showed trypanosomes in films, nor was it
infective, in doses of 8 c.c, on intraperitoneal inoculation into guinea-pigs.]
Section 3. — Patholog"ical Anatomy.
In surra, as in nagana, enlargement of the spleen is always
found in mice, rats, and dogs, sometimes in guinea-pigs, and only
rarely in rabbits. The splenic hypertrophy seems to bear some
relation to the large number of trypanosomes present in the blood
at the time of death.
In mice weighing 20 grammes the average weight of the spleen was
0'8 gramme; in rats of 170 grammes the spleen weighed 3-4 grammes;
in dogs weighing 20 kilogrammes the average weight of the spleen was
180 grammes. We have already mentioned the case of the dog of 9 kilo-
grammes in which the spleen weighed 210 grammes — about ten times the
normal weight. In guinea-pigs weighing about 465 grammes the average
weight of the spleen was 2-23 grammes, but the variations were very
great — for example, it weighed o'75 gramme and i'67o grammes in two
guinea-pigs of about the same weight (370 grammes). In rabbits weighing
about 1,380 grammes the average weight of the spleen was 3-5 grammes.
Apart from the splenic enlargement, surra does not as a rule
produce any macroscopic lesions, but in some autopsies on rats and
dogs we have seen pulmonary congestion and small subpleural
ecchymoses.
In buffaloes which had died of surra Penning found enlargement
of the lymphatic glands and liver, pericardial and submucous intes-
tinal haemorrhages, and, rarely, slight enlargement of the spleen.
[Massaglia^ has studied the changes in the organs of mice, rats, and
guinea-pigs experimentally infected with T. evansi. The organs affected
were the kidneys, liver, spleen, and heart, and, as in the case of animals
infected with T. hnicei, the kidneys showed the most marked changes.
These organs showed many haemorrhages, infiltration with small round
cells, and degenerative changes in the cells of the tubules, such as
vacuolation of the protoplasm, chromatolysis, and disintegration of the
nucleus. Massaglia remarks that these pathological changes, which
closely resemble those found in toxic conditions, appear to favour the idea
that the trypanosome elaborates a particular toxin, which has a special
effect upon the above-mentioned organs. If this be really the case, the
action of this toxin must be different from that of intracorpuscular
parasites. The latter affect and destroy the red corpuscles, which carry
nutriment to all the tissues ; the trypanosomes affect primarily the
excretory organs— the kidneys and liver — and secondarily the red blood-
corpuscles. Massaglia is of opinion that his observations are opposed to
Schaudinn's view that trypanosomes are a phase in the life-history of
intracorpuscular parasites.]
1 [A. Massaglia, Giorn. d. R. Acad, di Med. di Torino, v. 11, June 23, 1905 ;
abstract in Centralb. f. Bakter., I, Ref., v. 38 ; and in Bull. Inst. Past, v. 3, 1905.]
272 TRYPANOSOMES AND THE TRYPANOSOMIASES
[Thomas and Breinl found organic lesions similar to those seen by
them in animals infected with nagana, but the amount of pigment found
in the spleen was always very small.]
[In the brain of a rabbit which died three months after inoculation with
surra, Mott^ found masses of trypanosomes in nearly all the vessels.
' Single trypanosomes could be seen in the capillaries ; in thh larger
vessels solitary trypanosomes and whorls of trypanosomes and plasmodial
masses, which are either degenerated trypanosomes, consisting of a
zoogloeal mass, in which many deeply-stained nuclei and centrosomes can
be seen, or of amoeboid forms, described by Bradford and Plimmer.' In
spite of this severe blood infection, the vessels showed little or no inflam-
matory reaction. There was no perivascular cell infiltration, nor did the
nervous system show any lesions beyond chromolytic changes in the
ganglion cells.] y
Section 4. — Pathog"enie Agent {Trypanosoma evansi).
The trypanosorae of surra closely resembles that of nagana in
its morphology, as well as in the symptoms to which it gives rise.
Most of our experiments were made with trypanosomes obtained
from Mauritius ; but we were able to compare these parasites with
others of Asiatic origin, which were sent to us by Carougeau,
veterinary officer in the Pasteur Institute at Nha-trang, Annam.
The parasites coming from these two sources were found to be
identical.^
Trypanosoma evansi measures, on an average, 25 /«. in total length,
by i'5 /i in width, the free flagellum measuring about 6 /*. Larger
forms (30 iJ. long, by 2 to 2*5 ij- wide) are not uncommon, but these are
always multiplication forms. Smaller forms, measuring less than
22 jj- in length, are not found. The largest parasites (as much as
35 /i long) have been found in the blood of equines.
[Laveran and Mesnil,^ from their comparative study of the
trypanosomes of Indian and Mauritian sujrra, have come to the
conclusion that these parasites are practically identical in the blood
of infected dogs and mice. They are of the same size, and the
chromatic granules, when present, are neither very numerous nor
very large, and are situated in the anterior half of the body. The
posterior extremity varies in shape, but is usually pointed^ the
centrosome being generally very near the end of the body. The
undulating membrane has well-marked folds, varying from three to
five or even six in number.]
T. evansi is so much like T. brucei that it is unnecessary to give
a detailed description of it. We shall merely indicate the various
1 [Mott, ' Histological Observations on Sleeping Sickness and other Trypano-
some Infections,' Sleeping Sickness Commissiori s Report, No. vii., 1906 (see
p. 22). I am greatly indebted to Dr. Mott for allowing me to see a proof of his
paper before publication ; also for his permission to reproduce some of the plates
illustrating his paper.]
2 [For the recent observations of Laveran and Vassal on the trypanosomiasis of
Annam, see Appendix at the end of this chapter.]
3 [Laveran and Mesnil, C. R. Acad. Sciences, v. 140, 1905, p. 831.]
SURRA
273
minor differences that exist between these two species of trypano-
some. T. evansi is usually more pointed than T. hrucei. The
posterior end varies in shape, as it does in all trypanosomes, some-
times assuming the form of an elongated cone, at other times that
of a truncated cone. The nucleus and centrosome are the same
in the two species ; the free ilagellum is longer in T. evansi than in
T. hrucei, and the protoplasm usually contains fewer chromatic
granules in the former than in the latter species. Fig. 36 shows,
side by side, the trypanosomes of surra (/ and 2), of nagana {j and 4),
and of caderas (5 and 6), the last being characterized by the small
size of its centrosome.
Examined fresh in an ordinary slide preparation, T. evansi is
more motile than T. hrucei, and a parasite is often seen to travel
right out of the field of the microscope, which is very rarely observed
with T. hrucei.
Unfortunately, none of these characteristics — which are, more-
FiG. 36. — Trypanosomes of Surra, of Nagana, and of Caderas.
I and 2. Trypanosomes in the blood of a mule, Mauritian epizootic : n, nucleus ; c,
centrosome ; m, undulating membrane ; /, flagellum. The trypanosome in Fig. 2
is undergoing division ; it has two nuclei, two centrosomes, and the part of the
flagellum attached to the centrosome is undergoing division. 3 and 4. Trypanosomes
of nagana, one undergoing division. 5 and 6. Trypanosomes of mal de caderas, one
in process of division. Magnified about 2,000 diameters.
over, only of minor importance— is constant, and even with the same
strain of trypanosome the morphology varies slightly with the
species of animal in whose blood it is examined, and also with the
stage of the infection. It follows, therefore, that a differential
diagnosis between T. evansi and T. hrucei is impossible if based only
upon the examination of a very small number of parasites. Never-
theless, with a little practice one can learn to distinguish between
these two trypanosomes in well-stained preparations of blood con-
taining many parasites.
[Novy, McNeal, and Hare,^ from a study of stained preparations of
the Mauritian and Philippine trypanosomes, conclude ' that the two
organisms are quite unlike.' In the Mauritian trypanosome the total
1 [Novy, McNeal, and Yi&xe., Journ. of the Amer. Med. Assoc, May 28, 1904.]
18
274 TRYPANOSOMES AND THE TRYPANOSOMIASES
length was 33 /m, free flagellum 13 [j,, and the width (not including the
undulating membrane) 1-5 ytt to i-yyu. In the PhiHppine trypanosome the
dimensions were 22 /ix to 25 /u, 8 /x to 10 /j., and i"3 /«. to i"7 /x respectively.
These observers describe an enlargement at the free end of the flagellum
in the Mauritian parasite, but not in the Philippine. In the former
parasite the centrosome is 3-3 /* to 4 /x from the posterior end, whereas in
the latter it is only i /* to i -6 /x. The Mauritian trypanosome has a well-
developed undulating membrane with four distinct folds ; in the Philippine
trypanosome there are two or three less marked folds. Lastly, the
Mauritian trypanosome has a number of deeply-stained granules in the
anterior half of the body, the posterior half being quite free ; the Philippine
trypanosome, on the other hand, stains deeply in the posterior two-thirds.]
[As has been stated above, it is not possible to differentiate closely
allied trypanosomes by relying upon morphological differences, unless a
large number of individuals be examined. Although it is possible that
the Philippine and Mauritian trypanosomes are distinct organisms,
further experimental evidence is required before a definite conclusion can
be arrived at. This evidence may be obtained by means of cultivations
of the respective trypanosomes, and by immunization and cross-inoculation
experiments, such as Laveran and Mesnil have used successfully in the
case of nagana, surra, caderas, etc.]
Reproduction occurs by simple division, as in the case of
T. brucei p- the centrosome, nucleus, and flagellum divide into two
parts (Fig. 36, 2), and finally the protoplasm also divides. Some-
times further division takes place before the original protoplasm
divides, and in such cases, which are rare exceptions to the rule of
equal binary fission, one may find a large trypanosome containing
four nuclei and four centrosomes.
[Holmes^ has studied the evolution of T. evansi, and distinguishes
three varieties of the parasite which are recognisable especially by their
posterior ends. Thus the end may be (i) very elongated — probably
males ; or (2) short and truncated — females ; or (3) oval, like a snake's
head. — young females. He describes paired forms joined by their posterior
ends ; these he regards as conjugation forms. Of these paired forms, one
is always a male parasite, with a very elongated end ; the other is always
a female parasite (2 or 3, above). It is only the adult female (form 2)
which is seen to undergo division. Division is by ordinary binary longi-
tudinal fission or by transverse segmentation. In this way four amoeboid
forms may be produced, in which a flagellum develops, or which divide
into smaller forms. Holmes agrees with Bradford and Plimmer that
after conjugation the female form divides. He states that in the blood
the amoeboid bodies are few at any time, but that they are numerous in the
spleen, liver, and bone-marrow post-mortem. Holmes thinks they result
from the transverse division, and that they are carried to the liver, spleen,
and bone-marrow, where they develop into adult forms. He thinks also
that free nuclei of trypanosomes may give rise to new parasites. (Compare
Pricolo's observations on the mouse trypanosome, p. 102.]
The trypanosomes of surra agglutinate under almost the same con-
ditions as do those of nagana. We have obtained very good results
^ [It will be remembered, however, that Prowazek has recently described the
division of T. brucei as being very complicated.]
^ [Holmes, yi3z^r;z. Comp. Path, and Therap., v. 17, 1904, p. 210; abstract by
Mesnil in Bull. Inst. Past., v. 2, 1904, p. 954.]
SURRA
275
(primary, secondary, and tertiary agglutinations) by mixing a drop
of blood containing many trypanosomes with a drop of goat's serum.
With the serum of the horse we obtained only loose, primary rosettes.
The agglutinated parasites rapidly change, particularly in the centre
of secondary or tertiary colonies of rosettes, which rapidly become
granular. The parasites are agglutinated by their posterior ex-
tremities, as in the case of T. brucei.
When blood containing T. evansi is defibrinated or mixed with
citrated salt solution, and then kept at the room temperature or in
the ice-chest, the trypanosomes do not live very long. After three
days in the ice-chest some normally shaped parasites are seen, but
Fig. 37. — Philippine Sdrra Trypanosomes, from a Thirty-Eight-Day Culture,
DRAWN from a LIVING PREPARATION.
1,2. Simple forms. 3,4. Dividing forms from the same preparation. Magnified about
2,000 diameters, (After Novy, McNeal, and Hare.)
they are motionless or only feebly motile, and are no longer virulent.
The blood of a guinea-pig containing T. evansi, exposed for a quarter
of an hour to the temperature of liquid air ( — 191° C.) was still
virulent, for two mice inoculated with this blood became infected in
six and eight days, and died in fifteen and eighteen days respectively.
We have made attempts to cultivate T. evansi on blood-agar by
Novy's method. We succeeded only once in six experiments, and
the growth could be subcultured only once. The trypanosomes in
these cultures appeared in the form of small isolated motile parasites,
or of rosettes like those seen in cultures of T. lewisi, but much
smaller. All the parasites in the rosettes had the flagella directed
towards the centre of the rosettes. At the end of three months
motile parasites and rosettes were still seen in the cultures. The
18—2
276 TRYPANOSOMES AND THE TRYPANOSOMIASES
culture injected into mice on several occasions gave negative results ;
it appears, therefore, that the trypanosome, on becoming accHmatized
to artificial cultivation in vitro, had lost its virulence. The mice
which were unsuccessfully inoculated with the culture products
were not immunized thereby, for on subsequent inoculation with fresh
virulent blood they died as quickly as control mice.
[Novy, McNeal, and Harei have succeeded in cultivating the Philippine
trypanosomes. Tubes of blood-agar were inoculated on January i, 190^,
with the blood of an American cow suffering from Philippine surra.
They were then sent from the Philippines to America, where they arrived
thirty-eight days later. All three inoculated tubes contained motile and
developing trypanosomes when examined in America. The cultures were
quite different from those of T. lewisi and T. bnwei, inasmuch as there was
an entire absence of groups or rosettes. The trypanosomes were all
single and actively motile, and appeared to travel equally well with the
flagellum posterior or anterior. Another striking feature was the size of
the parasite and the length of the flagellum. An even more marked
peculiarity was the presence and arrangement of granules within the
parasites, and the distinct yellowish or greenish colour of the granules
and of the contents. These granules were present in large numbers, and
were 0-3 /j. to 0-5 /x in diameter. They were usually massed at the base
of the flagellum, and only a few occurred in the remainder of the body
(Fig. 37, I, 2). In the dividing forms the granules were arranged in two
parallel rows (Fig. 37, j, ^).]
[The flagellum was usually as long as, and often even longer than, the
cell itself The non-flagellated end, especially when blunt, showed a
rod-like tip or stylet, 2 yu, to 4 /x, or even 6 /^ in length (see Fig. 37).
There was no undulating membrane. The trypanosomes in culture
varied considerably in length. The majority were 25 /^ to 35 /i long, but
some were 40 /i or 50 /j. in length. The width varied from i'5 /x to 2'5 /i.]
[As the cultures aged, pear-shaped or spherical highly granular involu-
tion forms appeared, and, as in the case of T . lewisi and T. bnicei, these
involution forms eventually gathered into large groups or masses. Living
trypanosomes were found in one culture tube as late as the sixty-fifth
[All attempts to inoculate animals (white mice, white rats, and
guinea - pig), and to obtain subcultures on media containing varying
proportions of blood and agar, proved fruitless. These failures were
doubtless due to the age of the cultures (thirty eight days) when they
reached America. Similar results had previously been obtained with
T. brucei ; original cultures twenty-nine and thirty-eight days old failed to
infect mice.]
[Thomas and Breinl^ also obtained several cultures of T. evansi at
22° C, and at the room temperature. The organisms seen in a thirty-
three day old culture resembled those described above, and were non-
virulent for animals ; nor could subcultures be obtained from them. As
in the case of Novy's cultures, all the trypanosomes were single, and
actively motile.]
1 [Novy, McNeal, and Hare, /. cit., V. 2, p. 584.
'" Rouget, Ann. Inst. Past., v. 10, 1896, p. 716.
^ Schneider and Buffard, ' Notes conriraunicated to the Academie de M^decine
on July 25, September 19, October 3, and November 21, 1899, January, 1900.
Archiv. Parasitologie, v. 3, 1900, p. 124. Complete paper in Rec. m^d. ve'te'r.,
1900, pp. 81-105, 157-169, and 220-234.
' Nocard, Bull. Acad. Med., v. 64, meeting of July 31, 1900, pp. 154-163.
' Doflein, Die Protozoen, etc., Jena, 1901, p, 66.
314 TRYPANOSOMES AND THE TRYPANOSOMIASES
A few days later we^ called it T. rougeti, but Doflein's name has the
prior claim.
In 1902 Schneider and Buffard raised doubts as to the true
nature of the disease in horses whence Rouget derived his tr3-pano-
some, and suggested that he was dealing not with dourine, but with
nagana or surra. They came to the conclusion that other trypano-
somiases than dourine probably existed in Algeria. That such is
really the case has now been demonstrated by the researches of
Szewzyck and Rennes and of the Sergents (see p. 210 et seq.).
It is highly probable that the observation made by Chauvrat in
1892 was upon one of these trypanosomiases different from dourine.
As to Rouget's case, we shall continue to look upon it as one of
dourine, and later on we shall examine the validity of the arguments
brought forward by Schneider and Buffard against the diagnosis
of dourine, and of those adduced by Rouget in support of his
diagnosis.
Section 2, — Dourine in the Equidae,
We quote almost verbatim from the excellent work by Schneider
and Buffard the account of the symptoms of the natural affection
as it occurs in reproductive Equids.
Horse. — Dourine in horses may be acute or chronic, the former
being much less common than the latter.
Chronic Dourine. — In the chronic form there are three stages,
which as a rule are fairly well defined :
Stage I. Presence of Localized (Edema. — The first signs of the
disease in the stallion are visible from the eleventh to the twentieth
day after coitus. The disease nearly always starts with a little
oedema at the lower part of the sheath, which may be overlooked,
especially if the veterinary officer or the head of the stables has not
noted the condition of the sheath before the covering season.
This oedema gradually extends along the lower part of the sheath
to the scrotum and the inguinal region, and may even reach the
abdominal walls. Usually the swelling is cold and painless, but
sometimes it is hot and tender to the touch. The end of the penis
becomes infiltrated, and the horse frequently gets slight erections.
The superficial lymphatic glands in the groin are enlarged, and this
enlargement is often unilateral when the initial cedema occurs only
on one side.
In the mare the symptoms are less marked than in the stallion.
They consist at first of a unilateral or bilateral swelling of the vulva,
often extending up to the anus, a bright red colour of the vaginal
mucoias membrane, and a gradually increasing mucoid or viscid
discharge.
The appetite always remains good ; the temperature oscillates
between 38° and 38"5° C. [ioo'4° and ioi-4° F.] ; coitus is still
1 Laveran and Mesnil, C. R. Acad. Sciences, July 15, 1901, p. 131.
DOURINE
315
possible, the horse easily getting an erection. Later on, about a
month after the appearance of the first symptoms, the initial swell-
ings partially subside and become localized to the genital organs.
Sometimes the swelling disappears almost entirely, the end of the
penis alone remaining infiltrated. At this time the kidneys are
tender on pressure, and the animal almost gives way under the
weight of a rider. The horse gets winded after a short trot and
already shows signs of wasting.
Stage 2. Presence of Patchy Infiltrations of the Skin (plaques).
These constitute the only pathognomonic sign of the disease,
and they usually appear forty to forty-five days, sometimes two
months, after the infecting coitus. The plaques are 'salient and
Fig. 42.— Horse suffering from Dourixe at the End of the Second Stage.
Note the emaciation, the great feebleness of the hmd quarters, and the flexion of the
letlock in left hind-leg. (From a photograph in Xocard's collection, lent by \-allee.)
rounded,^ and look as though a metal disc had been slipped under
the skm ' (Pease). They vary in size from a florin to the palm of the
hand. The hair over them bristles and the skin is thickened.
Sometimes, instead of these well-defined plaques, the skin is slightly
swollen in those parts where the plaques usually occur. In some
stallions they are at times oedematous, and in such cases when they
disappear a httle fluid exudes, which causes the hair to become
matted together. The duration of these patches is verv variable :
they may appear in the morning and be gone again the same night,
or they may persist for five to eight days. They occur most com-
monly on the sides and hind-quarters, but sometimes upon the neck
and shoulders, and on the thighs.
3i6 TRYPANOSOMES AXD THE TRYPANOSOMIASES
At this period wasting is very marked (see Fig. 42). The animal
constantly lies down, and can only get up with difficulty, as if its
hind-limbs were paralyzed. When walking it drags its hind-feet
along the ground, and when the weight of the body is supported
by either hind-leg there is extreme flexion of the fetlock. Often
the synovial sheaths of the joints and tendons of the hind-limbs are
swollen. The inguinal glands become enormously enlarged and
sometimes ulcerate. The glands of the chest and intermaxillary
space are also congested and swollen. The appetite is good, and
may even be enormous, the eye is often fixed and staring, and the
temperature often rises to sg'' C. [102-2° F.] in the evening, falling
again in the morning to 38-5° C. [101-4° F-]- Connection is prac-
tically impossible for stallions, while mares very generally abort.
Stage 3. Presence of Profound AncEinia and Paraplegia. — At this
stage the mucous surfaces are very pale, wasting is marked, the
appetite becomes capricious, and so profound is the weakness that
the sick animals cannot move from place to place without propping
themselves up against a wall or other support. Often there occur
superficial abscesses, which show little tendency to heal ; and some-
times there are eye troubles, such as conjunctivitis and ulcerative
keratitis. Micturition is difficult and the urine is thick. The joints
of the limbs and spine crepitate on the slightest movement, and
fractures frequently occur. Towards the end there is complete
paraplegia, and the animal falls down, never to rise again. Its
sensibility to pain is so much diminished that the animal may be
pricked or even cut without showing the least sign of pain. We
shall see that these nervous symptoms are often associated with
patches of softening in the spinal cord.
The duration of the disease is variable — usually it is from two to
six months, exceptionally it lasts one or two years. Schneider and
Buffard^ record' two cases of cure, but it is possible that these cases
relapsed again later.
[Baldrey gives the duration as twelve to eighteen months ;
Lingard states that certain breeds of horses can retain the materies
morbi of dourine in their system for one or four years, just as cattle
and camels in India can tolerate the trypanosome of surra, or its
' developmental ' forms, in their blood for one to three years. A
stallion whose nervous system was studied by Mott died twenty-
seven and a half months after the infecting coitus.]
[According to Baldrey, dourine is fatal and incurable except in
the first stage. Castration performed at this stage of the disease
seems to benefit some cases, but if done in the second stage it is
useless. Pease states that dourine is an old disease in India, and
therefore less deadly than in Europe. He estimates that 70 to
80 per cent, of infected mares die of the disease in India.]
Acute Dourine. — Sometimes dourine runs an acute course, and,
^ Schneider and Buffard, ' La Prophylaxie de la Dourine,' p. 4.
DOURINE
317
after the initial cedema, a sudden acute paralysis or attacks of
vertigo may carry off the animal in a few days. In the mare this
acute form is more common than in the stallion, and usually para-
lysis occurs suddenly a few days after the appearance of the plaques.
Experimental Dourine. — Subcutaneous inoculation of the virus
reproduces the natural disease in the horse and donkey, the incuba-
tion period varying from seven to twenty days, according to the
number of trypanosomes injected. There is no difference between
the experimentally produced disease and that occurring naturally.
The signs and symptoms, as well as the course of the temperature,
are the same in the two cases. Sometimes the temperature is very
;oui(s
59
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39'
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Fig. 43.
A. Temperature Chart of a Horse with Dourine during the First Month
AFTER Inoculation.
This animal, a thoroughbred stallion, was injected intravenously with 20 c.c. blood from
a horse.
B. Chart of a Donkey ( ^ ) during the First Month after the Infecting Coitus.
This animal was covered by a diseased stallion.
(Nocard's charts, lent by Vallee.)
high, just as at the onset of nagana and surra. Nocard has recorded
several well-marked cases of the kind. ' I have been able,' writes
Nocard (Soc. Biologie, May 4, igoi), ' to kill strong healthy horses
in four, six, and eight weeks, and the curve of their temperature was
identical with that seen in surra and nagana.'
We reproduce (Fig. 43, A) a temperature chart of experimental
dourine in which the temperature was above 39"5° C. [i03"2° F.] on
several days during the second week after inoculation. Cases of the
natural disease have also been recorded in which the temperature
rose to 40° C. [104° F.] at the onset.
3i8 TRYPANOSOMES AND THE TRYPANOSOMIASES
Donkey. — The symptoms of dourine in the donkey, both male
and female, are very indefinite, and as a rule a male donkey is
recognised as being infected by the victims he makes amongst the
females with which he has had connection. The only sign which is
invariably present is oedema of the end of the penis ; cedema of the
sheath appears later, but cutaneous plaques are very rarely present —
only in 2 per cent, of the cases.
In less resistant male donkeys dourine runs a course similar to
that in the horse, but such cases are rare. Under those conditions
wasting is extreme, the sheath and scrotum become swollen, and
finally paralysis supervenes. Some donkeys (c?) live for more than
three years with dourine, and the Arabs state that some animals
even recover from the disease, but we know of no authentic case of
recovery from dourine.
The experimental disease in the donkey runs a clinical course
similar to the natural disease in that animal (see Fig. 43, B).
Distribution of the Trypanosome in the Body. — ' It is
difficult to find the parasite in naturally infected animals. It can
be found in the blood taken from the region of the oedematous
swellings and plaques, but we have rarely seen it in the blood
obtained from other vessels. The fluid which escapes immediately
after puncturing the oedematous swellings or plaques appears not to
contain the parasite, but if this fluid be tinged with blood the
parasite may be found in it, and the more blood there is present the
more numerous are the trypanosomes. Two conclusions may be
drawn from these facts : first, that the trypanosome is really a blood
parasite; and, secondly, that very probably the swellings and
cutaneous plaques are due to embolism caused by masses of the
parasites blocking the small bloodvessels.'
' The best time to find the trypanosome in the plaques is on the
first appearance of the latter — it is then that the parasite should be
looked for, and the success of the examination depends upon this condition
being fidfilled. As the cutaneous lesion extends, the parasite
becomes more difficult to find in preparations, and some hours
after the appearance of the lesions the parasite can no longer be
found. Apparently they persist for a longer time in the oedematous
swellings. . . .'
' At the outset of the disease we have constantly found the
trypanosome present. At a later period, when the infiltrated areas
in the skin have disappeared, the trypanosome seems to be less
freely distributed throughout the body. Blood examined in fresh
preparations shows only a few parasites, but this blood is infective
on injection ' (Schneider and Buffard).
[Lingard^ states that the infection does not become generalized
— that is to say, the virus does not enter the circulation — until from
thirty to forty days from the time of the primary infection. Some-
' [Lingard, Centralb.f. Bakter., I, Orig., v. 37, p. 537.]
DOURINE 319
times it may be as long as ten to twelve or more months before the
blood infection occurs in stallions, especially if the swelling of the
sheath be detected early and the animal be segregated, given rest and
good food, and all connection stopped. When the trypanosome gets
into the circulation, plaques may occur at any time after an interval
of a few days, and may recur for long periods — more than a year.
The blood is not infective on injection during the ' latent ' stage
of penile swelling. It appears, says Lingard, that the trypanosomes,
or their developmental forms, remain shut off for the time being in
the affected area.]
[Lingard is of opinion that the plaques are due to a circumscribed
angio-neurotic oedema, occasioned by the advent of the trypanosome,
or its developmental forms, in the papillary layer of the skin. He
thinks that a toxin elaborated by the trypanosomes produces dilata-
tion of the capillaries and a localized increased secretion of lymph
around.]
[Lingard's view of the origin of the plaques is based upon the following
observations : In blood drawn from a recent plaque, fully-formed, but
small-gized, trypanosomes are present. These might have developed, says
Lingard, from the amoeboid or plasmodial form, after the latter had been
deposited in the plaque. Later on, as long as the oedema persists, trypano-
somes or developmental forms are present at some part of the oedematous
area, the mature trypanosomes diminishing in number — which may be
due to the action of the toxin — and the developmental forms increasing.
Eventually only developmental forms of the parasite remain in the plaque,
and on the disappearance of the latter they return to the general circulation.
Similar developmental forms were found in the fluid obtained from the
secondary swelling arising at the seat of subcutaneous inoculation with
infective blood. In a donkey inoculated subcutaneously with 20 c.c. horse
blood, the first immature form was found on the nineteenth day, and the
first mature trypanosome only on the thirty-ninth day.]
[Lingard has found that blood or sero-sanguineous fluid taken from
a plaque, from which the mature trypanosomes have disappeared, is para-
siticidal in vitro, giving rise to loss of motility and granular disintegration
of the parasites.]
[Mott does not agree with the view that the plaques are due to
embolism by trypanosomes. He thinks that, by analogy with the
origin of herpes zoster, an inflammatory irritation of the posterior
spinal ganglia, as these become successively affected by the noxious
agent, causes the eruption of the cutaneous plaques. It has, more-
over, been shown experimentally by Bayliss that stimulation of the
posterior roots produces vaso-dilatation. In the blood or oedema
fluid produced, as suggested by Mott, by the irritation of the spinal
ganglia, the trypanosomes may find suitable conditions for multiply-
ing by fission. According to Mott, therefore, the presence of many
trypanosomes in the blood and fluid from a plaque would be the
result rather than the cause of this lesion. The eruptions seen in
human trypanosomiasis might be similarly accounted for by irritation
of the neurotrophic centres in the spinal ganglia.]
320 TRYPANOSOMES AND THE TRYPANOSOMIASES
[Trypanosomes are present, though in very small numbers, in
the general circulation. Schneider and Buffard^ state that, during
an epidemic of dourine in 1904 in the department of Basses-
Pyr6n6es, they were able to find the trypanosome in the peripheral
blood of two mares out of four examined.'' The trypanosomes were
very scanty, and were found only after a long and tedious examina-
tion. Marek, in Hungary, also succeeded, after a prolonged search,
in finding the trypanosome in the blood of a sick stallion (quoted by
Schneider and Buffard).]
[Lingard states that when the plaques are numerous and con-
stantly changing, even small quantities of blood are infective on
injection ; but when the plaques are very scanty, it may be difficult
to infect an animal even with large quantities of blood.]
[Trypanosomes or developmental forms can be found — after
staining and careful examination — in the semen of infected stallions.
Mares infected by coitus will in most cases sooner or later develop
the trypanosome in the vaginal mucus, and it may be observed in
the mucus at intervals during the subsequent course of the disease.
Sometimes the trypanosome may be present for months in the
vaginal mucus without the animal showing any signs of ill-health.
Mares inoculated subcutaneously with infective blood — ^anywhere
except in the external genitals — may develop plaques and cerebro-
spinal symptoms, but the vaginal mucus, when free from blood, may
be non-infective in such cases (Lingard).]
[Baldrey also states that the trypanosomes may live in the
vaginal mucous membrane and discharges of mares, and in the
urethral and seminal fluids of stallions for an indefinite period.]
[In animals succumbing to an acute attack of the disease, ac-
companied by nervous symptoms, developmental forms of the
trj-panosome occur in the cerebro-spinal fluid (Lingard). In a very
chronic case — lasting twenty-seven and a half months — studied by
Mott numerous stained specimens of the fluid were examined for
the T. equiperdum, but unsuccessfully.]
Pathological Anatomy. — At the autopsy the most definite and
characteristic lesions are found in the lymphatic glands and in the
spinal cord.
The lymphatic glands are much enlarged, congested, and softened.
The first glands to be enlarged are those of the abdomen and hind-
quarters. Gradually the glands of the anterior part of the body
become enlarged, and in chronic cases the lymphatic system
throughout the body becomes affected. According to von Than-
hoffer, the glands on section show dark grey patches, due to the
remains of capillary haemorrhages.
^ [Schneider and Buffard, Rev. ghi. med. vc't., June, 1904 ; Aizn. Inst. Past.,
V. 19, 1905, p. 715. Abstract by Mesnil in Bull. Inst. Past., v. 4, 190b, p. 166.]
^ [These four mares were suspected of dourine after being covered by a diseased
stallion. Three of them died with the classical symptoms of the disease. The
stallion had covered thirty-seven mares, but the remaining thirty-three did not
become infected. The stallion is said to have recovered eventually.]
DOURINE 321
The lesions in the spinal cord are most marked in the lumbar and
sacral regions. The cord is in parts transformed into a reddish,
diffluent pulp, the softened portions being sometimes as much as
6 to 8 centimetres (2 to 3 inches) in extent. No other trypanosome
disease gives rise to such a condition, and even in dourine it is found
only when the paralysis has been of long duration. On histological
examination, Marek,i a Hungarian observer, found degeneration of
the fibres of the posterior columns, the other parts of the cord (the
grey matter and the rest of the white matter) being healthy. Some
fibres, particularly the sensory, of the roots of the spinal nerves are
also degenerated. The nerves of the hind-limbs also show degenera-
tion of some of the fibres, those of the fore-limbs being less affected.
Owing to these anatomical changes which occur in dourine, Marek
'Calls it polyneuritis infeciiosa equorum.
[In an Arab stallion which suffered from chronic dourine and
during the course of its illness exhibited 156 cutaneous plaques,
together with marked symptoms of paraplegia, Mott- found wide-
spread changes in the spinal- cord, posterior spinal ganglia, and
nerve roots. The notes of this case sent by Lingard to Mott are as
follows : The infective coitus occurred on May 4 to 6, 1903 ; partial
paraplegia appeared on February 25, 1904 ; death on August 15,
1905, twenty-seven and a half months after infection. Post-mortem
a considerable quantity of gelatinous exudation was found round the
lumbar portion of the spinal cord, and a smaller amount around the
cervical enlargement, and a certain quantity of cerebro-spinal fluid
escaped from within the membranes on removal.]
[The following histological changes were observed by Mott :
Intense chronic inflammation of the posterior spinal ganglia — most
severe in the lower dorsal and lumbo-sacral regions, but fairly
marked also in the upper regions of the cord. Where the inflam-
mation was most intense the ganglion cells were most affected — in
some cases being completely destroyed, and their place occupied by
inflammatory products. Associated with this extensive neuronic
destruction in the lumbar region, there was extensive posterior
root destruction and system-degenerative sclerosis of the posterior
columns. This lesion, which resembles that of tabes dorsalis, and
the comparatively normal appearance of the anterior roots, 'would
suggest that this animal suffered with a sensory paralysis of the
hind-limbs analogous to tabes dorsalis, rather than a polyneuritis '
(Mott).]
[Throughout the grey matter of the spinal cord the ganglion
cells showed marked chromolytic changes, and the vessels exhibited
' [Marek, Zeitschr.f. Tiermedizin, 1900, p. 401 ; 1904, p. 13.]
2 [Mott, Proc. Roy. Soc, Ser. B, v. 78, igoS, p. i ; Brit. Med. Journ., 1906, ii.,
pp. 300, 1775-1777); also Centralb. f. Bakter., I, Ref., v. 39, 1906, pp. 1-9. In the
last two papers Mott states that he has found lesions similar to those described in
the text in four other cases of equine dourine, the tissues of which were sent to him
by Lingard.]
' 21
322 TRYPANOSOMES AND THE TRYPANOSOMIASES
evidence of chronic inflammation, with scattered capillary hemor-
rhages. The changes were most marked in the lumbo-sacral region,
infiltration and thickening of the connective tissue septa, infiltration
of the nerve roots and of the vessel walls with lymphocytes and
small round cells. Mott states that the condition simulated an acute
syphilitic meningitis in many ways, except that in this case there
was only occasional evidence of an obliterative arteritis.]
[There was also evidence of a general irritation of the central
nervous system, manifested by a subpial and septal proliferation of
the neuroglia, a chronic interstitial inflammatory change which, in
the spinal cord, was not limited to the posterior columns. The
membranes at the base of the brain also seemed thickened, and
sections of the peduncles and interpeduncular structures showed a
subpial and septal neuroglia proliferation similar to that seen in the
lumbar region.]
[These changes in the nervous system in dourine are like those
seen in chronic cases of infection with T. gambiense — sleeping sick-
ness — and appear to be due to the presence of an irritative agent in
the lymphatic system. In dourine this starts ' in one seat of primary
infection, extends to the inguinal glands, thence presumably by
the pelvic lymphatics to the lumbo-sacral plexus and the posterior
lumbo-sacral roots to the central nervous system ; consequently the
lower part of the spinal cord — and especially the posterior column —
is first and most affected. In the case of sleeping sickness there
may be any number of seats of infection, but the cervical glands are
nearly always markedly involved ' (Mott).]
The other lesions are less characteristic and less important —
gelatinous exudations under the skin, serous effusions into the pleural
and peritoneal cavities, wasting, and pallor of the muscles, which
show areas of fatty degeneration and atrophy of the fibres.
[Moraxi has studied the eye changes in dogs and goats infected with
dourine, and in goats infected with nagana. The most characteristic lesion
— which when it occurs in animals is very suggestive of trypanosomiasis —
is an interstitial keratitis. It is caused by the multiplication of the para-
sites in the interlamellar spaces of the cornea. The multiplication of the
trypanosomes is followed by a leucocytic infiltration, and later on by a
formation of new bloodvessels. These changes may lead to complete dis-
organization of the cornea, or they may disappear and leave only slight
traces, especially in resistant animals, such as goats.]
Section 3. — Experimental Dourine in Dogs, Rabbits, Rats, and
Mice. Refractory Animals.
The dog, rabbit, and, in certain cases, the rat and mouse, are
susceptible to the trypanosome of dourine. [It has been shown that
buffaloes (Pease) and other bovines, as well as monkeys (Mesnil and
Rouget), are likewise susceptible to T. equiperdujn.]
1 [V. Morax, Ann. Inst. Past., v. 21, 1907, pp. 47-6T.]
DOURINE 323
The infection may be transmitted by all the ordinary methods
of inoculation. It progresses more rapidly after intraperitoneal or
intravenous injection, while intracerebral or intraocular inoculation
hastens the appearance of nervous symptoms. Subcutaneous inocula-
tion is best for studying the form of the disease most like the natural.
Rouget was the iirst to recognise that, contrary to what obtains
in the case of the other pathogenic trypanosomes, ' solution of continuity
of the integuments is not indispensable, for the trypanosome can
pass through healthy mucous membranes. A drop of blood, rich in
parasites, placed in the lower conjunctival sac of a rabbit, is sufficient
to infect the animal. We have seen a case of probable infection by
the vagina. A male rabbit recently infected was intentionally placed
in a cage with a healthy female, which contracted the disease.'
This experiment has been repeated many times by Schneider
and Buffard. In their paper (pp. 226-228) they mention the follow-
ing instances : (i) Two dogs became infected after having had
connection with a bitch which was experimentally inoculated by
introducing into the vagina some blood from a plaque in a diseased
stallion ; (2) a rabbit ( ? ) contracted dourine after coitus with a
rabbit experimentally infected by subcutaneous inoculation ; (3) a
rabbit (c?) became infected after covering another suffering from
dourine. A bitch or a rabbit may be infected by carefully placing on
the vulva some drops of blood or oedema fluid containing trypano-
somes.
[It has already been mentioned (p. 219) that the Sergents in-
fected four animals out of eight, by way of intact mucous membranes
— conjunctival and genital — and that six similar experiments with
dehab were all negative. In this way the Sergents were able to
differentiate dourine from other Algerian trypanosomiases.]
' The absorption by the digestive tract,' says Rouget, ' of different
substances rich in parasites has never been followed by infection.'
Naturally, the material inoculated will not give rise to dourine
unless it contains the specific trypanosome. It is important to bear
this in mind when dealing with blood which, as we have seen,
always contains few parasites. It explains the contradictory results
obtained by the older investigators. It is often necessary to inject
5, 10, 15, or 20 c.c. of blood to get a positive result.
Nocard found in 1892 that the softened parts of the spinal cord
were also infective.
The dog being very susceptible to dourine, the injection into
that animal of blood-stained oedema fluid, or, failing that, of blood,
affords a valuable means of diagnosis in doubtful cases — as, for
example, in donkeys — but it should always be remembered that
when one has to inject blood, from 10 to 20 c.c. should be inocu-
lated. [But the diagnosis of dourine, even by animal inoculation,
is often difficult. Thus Schneider and Buffard's stallion, which
served thirty-seven mares and infected four of them (see p. 320, foot-
21 — 2
324 TRYPANOSOMES AND THE TRYPANOSOMIASES
note 2), never showed trypanosomes, and its blood was not infec-
tive on injection into dogs and rabbits.]
Dogs.— The dog never suffers from the disease naturally, but is
very susceptible to experimental inoculation with virulent material
from infected Equidae.
In 1892 Nocard^ showed that the dog contracts a disease closely
resembling dourine in horses, when inoculated in the anterior
chamber of the eye with some softened nerve substance from the
spinal cord of a diseased horse.
Rouget {loc. cit.) also studied the disease experimentally in the
dog. He drew particular attention to the eye lesions (exophthalmos,
keratitis, followed by staphyloma, and hypopyon), to the very marked
motor troubles, and to the pronounced cedema of the external genital
organs.
Schneider and Buffard gave dourine to the dog by subcutaneous
inoculation with the blood or fresh spinal cord of infected animals.
Six to eight days after inoculation the animals have a tempera-
ture of 39° or 39"5° C. [io2'2° or i03"2° F.]. From twelve to twenty
days after inoculation, there is extensive oedema of the abdominal wall,
usually around the site of inoculation, and also swelling of the genital
organs — acute balanitis in the male, acute inflammation of the genito-
urinary mucous membrane, with an abundant vaginal discharge in
the female. There is continued fever (39° to 39'5° C.) and the
appetite is good, although the animal appears restless and ill. The
gait is hesitating ; the kidneys are pushed upwards, and are very
tender on pressure. The swelling of the genital organs alone
persists.
When the disease has established itself, the signs and symptoms
are : wasting, in spite of a good appetite ; trouble with locomotion,
especially with the hind-limbs; localized cedemas; and cutaneous
plaques. The latter, which are only visible in animals whose hair has
been cut short, resemble the plaques seen in horses. If they are
punctured soon after they appear, the blood which escapes contains
many trypanosomes. Other symptoms are arthritis, with effusion
into the joints, and various eye troubles, such as opacity of the
cornea and lens, purulent conjunctivitis, and ulcerative keratitis, with
hypopyon. Fever is always continued, the temperature being
39° to 40° C. [i02"2° to 104° F.]. In very resistant animals the
temperature falls to between 38*3° and 38'9° C. [101° and 102° F.]
at the end of three to four weeks.
There are always periods of improvement, but these remissions
are merely temporary, the disease nearly always terminating fatally.
Nevertheless Nocard has seen dogs recover after having been
extremely ill.
This stage of the disease lasts about a month. Sometimes death
occurs rather rapidly after an attack of paralysis. More often
1 Nocard, C. R. Acad. Sciences, v. 114, 1892, p. 1S8.
DOURINE 325
emaciation becomes extreme, so that the animal is a mere skeleton,
and finally it refuses food altogether. On the slightest exertion
it becomes dyspnceic. Death occurs suddenly, probably from
syncope.
[Peasei states that, according to Schneider and Buffard, certain
breeds of dogs easily contract dourine by subcutaneous inoculation
and by coitus, while other breeds are very resistant. Pease found
the same thing with pariah dogs in Lahore. Of twelve dogs and
bitches inoculated in various ways, only one showed any symptoms
whatever, although control animals — other breeds of dogs — were
readily affected. These pariah dogs, which were refractory to
dourine, as well as the one which showed a slight local infection
and then completely recovered, were highly susceptible to surra.]
[Thomas and Breinl^ have experimented upon several puppies and one
adult dog. The incubation period in the former was from four and
a half to eleven days (average seven days), in the latter thirteen days.
The total duration of the disease was twenty-two to sixty-four days
(average five to six weeks) in the puppies ; the adult dog lost flesh and
became very anaemic, but recovered in two and a half months. Four
months later it was killed, and a pup inoculated with its blood developed
the disease. In the puppies the chief symptoms were : profound ansmia,
loss of weight, cedema of the genital organs, hind-limbs, and abdomen,
purulent discharge from the eyes and nose, and in one case partial paralysis
of the hind-limbs. Trypanosomes were at first very scanty in the blood,
but increased from about the third week onwards ; many dividing forms
were then also seen in the blood.]
[Post-mortem the spleen and lymphatic glands were moderately
enlarged ; there was often much fluid in the serous cavities, and small
petechial haemorrhages on the surface of the lungs. The serous effusions
and oedematous patches contained many trypanosomes. There was
frequently considerable cedema around the lumbar region of the cord.]
Rabbits. — Rouget clearly recognised the susceptibility of the
rabbit to the trypanosome of dourine.
' Fever is irregular and does not, as a rule, appear during the first
few days after inoculation. The temperature fluctuates between
39-5° and 40° C. [103-2° and 104° F.] , without falling much in the
morning. Then the temperature becomes normal, but from time to
time there are sudden rises which cannot be accounted for on
examining the animal.
' One of the earliest signs is localized or general oedema of the
ears, which hang down, are hot, and pit on pressure. The dilated
vessels are seen to be gorged with blood. The fluid which exudes
on incision contains the parasite, often in large numbers. The
swelling persists for one or more weeks, then further changes take
place : the veins become thrombosed, the skin becomes dry and
scaly, the hair falls out, and on two occasions we have seen sloughs
1 [Pease, Vet. Journ., v. 9, 1904, p. 187.]
2 [Thomas and Breinl, Thompson Yates and Johnston Lab. Reports^ v. 6,
part 2. 1905, p. 32. jMesnil remarks {Butt. Inst. Pavt, v. 4, p. 124) that their
virus, of which they do not give the source, was of the Schneider-Buffard type.]
326 TRYPANOSOMES AND THE TRYPANOSOMIASES
the size of a shilling, which, on removal, left a perforation of the
cartilage. . . .
' Later on the limbs become swollen and ulcerated, the claws are
long and brittle, the skin is covered with scabs, and the hair falls out.
At the same time there is weakness of the hind-limbs, which may
go on to complete paraplegia and involve the sphincters. The
general condition of the animal rapidly gets worse, and in spite of a
good appetite, wasting continues, so that the animal often loses more
than a third of its original weight.
' There is a muco-purulent conjunctivitis, the parasite being
found in the exudate. The eyelids are swollen and irritated by the
pus which adheres to them. We have not observed any well-defined
lesions of the eyeball, such as are seen in the mouse and dog.
'In some animals there is a discharge from the nose, and the
nostrils are covered with thick, adherent crusts, beneath which the
tissues are destroyed and the bones exposed.
' The external genitalia are always affected. In the female the
vulva and anus are swollen, the congested mucous membrane bleeds
easily, and sometimes shows one or two indolent ulcers. In the
male there are cedema of the sheath and paraphimosis, and the end
of the penis thus exposed may necrose. We have seen three cases
in which the skin of the scrotum sloughed and exposed the testicle.
' In the rabbit the disease lasts from one to three or four months,
varying with the age and weight of the animal. Death occurred in
all the animals (twenty-five in number) inoculated by us.'
As in the Equidse and in dogs, the parasites are comparatively
scanty in the blood, and are present irregularly and intermittently ;
but, says Rouget, ' we have not been able to establish any relation
between the febrile paroxysms observed and the presence of the
parasite in the blood. In order to discover in which parts of the
body the trypanosome may be found, we sacrificed several rabbits
which were obviously infected, but whose blood failed to show the
parasite on microscopical examination. We found them in the spleen,
in the ocular media, on the mucous surfaces, and in the plaques, but
never in the marrow of the bones.'
We have ourselves inoculated two rabbits with the cedema fluid
of an infected dog, one in the vulva and the other subcutaneously.
The former quicTily showed the train of symptoms so well described
by Rouget, and died in two and a half months. The latter showed no
obvious signs until after two and a half months, and died nine months
after the inoculation, having almost completely recovered from the
cutaneous and ocular lesions. At the seventh month after inocula-
tion its lesions so closely resembled those of two rabbits with nagana
which we had under observation at the same time that they were
scarcely distinguishable from them ; but in the two rabbits with
nagana the lesions had appeared much more quickly, and death
rapidly supervened.
DOURINE 327
' At the autopsy,' says Rouget, ' in addition to the lesions already
described, one finds enlargement of the lymphatic glands, exudation
into the peritoneal cavity, and congestion of the liver and spleen.
The remaining organs appear healthy. The parasite is found every-
where — in the various fluids, in the viscera, in the glands (testicles),
and on the mucous surfaces (urethra).
' Rabbits from which the spleen had been removed were inocu-
lated after they had recovered from the operation, and the disease
ran the same course as in control animals.'
[Thomas and Breinl have recorded similar results in the rabbits
inoculated by them. The incubation period after subcutaneous
injection was six to eleven days, and death occurred, as a rule, in
twenty-four to 108 days. Some animals were still alive six months
after inoculation.]
Rats and Mice. — The observations of Rouget on the one hand,
and of Schneider and Buffard on the other, differ materially as to
the susceptibility of rats and mice. This has led to a good deal of
discussion, in which these scientists have taken a prominent part.
Let us consider first the facts as stated by Rouget : ' On subcu-
taneous injection of small doses of the virus {^ c.c. of a mixture of
broth and infective blood, in such a proportion that one drop of the
mixture shows one or two parasites in each field of the microscope),
trypanosomes can be found in the blood taken from the tip of the
tail at the end of the third day, aiid on three occasions they were
found in twenty-four hours. " After intraperitoneal injection the
parasite may be found in the blood after thirty-six or forty-eight
hours. The injection of large doses of the virus shortens the incu-
bation period. The parasites increase rapidly, and they go on
multiplying until death, which occurs from the fifth to the eleventh
day after inoculation. At death the trypanosomes are more
numerous than the red corpuscles.
'The mice do not appear ill until just a few hours before death,
when they sit quite still and huddled up, the eyes closed, and the hair
dry and bristling. They are insensitive to external stimuli, and the
corneas become white and opaque, either partially or completely.
' At the autopsy there is sometimes a blood-stained exudation in
the peritoneal cavity, but the most noticeable lesions are hypersemia
of the abdominal parietes and enlargement of the liver and spleen —
the latter weighing as much as 2 grammes. The spleen is glistening,
swollen, and of a pink colour ; the liver is markedly congested, and
the bladder is distended with urine. The other organs look normal,
and the lungs appear quite healthy. The lymphatic glands near the
site of inoculation are enlarged. The parasite is found in the sub-
stance of all the internal organs, in the ocular media, and in the
testicles, but not in the urine or in the contents of the ahmentary canal.
' Grey mice and white rats react in the same manner, but the
disease lasts a little longer in the latter (fifteen days).
328 TRYPANOSOMES AND THE TRYPANOSOMIASES
' Sewer rats present certain peculiarities. Some are susceptible,
others are quite refractory ; in others, again, the parasite multiplies
in the blood for a time — as can be ascertained by systematic
examination of the blood — then permanently disappears, the animal
remaining in good health. Of thirty rats caught in the drains of the
military hospital at Constantine, seven died of the infection, nine
were quite refractory, and fourteen were only slightly susceptible.'
Nocard, who experimented with the trypanosome of Schneider
and Buffard, says {loc. cit., p. 162) : ' I have never succeeded in killing
a single mouse. At first my mice showed a few parasites in the blood
of the tail six to eight days after inoculation, but now, after more
than twenty-eight passages through the dog, not only do the mice
not die, but they appear absolutely refractory.' Later^ he says :
' As regards the rat, which at first appeared as refractory as the
mouse, intracerebral inoculation killed a young rat about six weeks
old, and during the last few days of its life trypanosomes in appre-
ciable numbers were found in its blood. Since that time the parasite,
which in this way had become virulent for the rat, killed — in from six
to fifteen days — all the white rats inoculated, even subcutaneously,
with a trace of infective blood.' Nocard told us that he lost this
virulent strain of the trypanosome during the vacation of 1901, and
could not succeed in getting another.
Schneider and Buffard never succeeded in infecting either rats or
mice with their trypanosomes,^ and they state that Billet and
Marchal, in Constantine, similarly failed to infect grey mice.^
This difference in their experimental results led Schneider and
Buffard to suppose that Rouget's horse was not suffering from
dourine.*
Rouget^ hastened to reply to the criticism, and mentioned the
fact that he had inoculated all his rats and mice with a virus which
had been passed through the rabbit, which neither Schneider and
Buffard nor Nocard had done.
Working on those lines, Nocard tried again to infect mice, and
we quote the following remarks upon the subject, which he wrote to
us in June, 1903 :
' Nocard, C. R. Sac. Biol., May 4, 1901, pp. 464-466.
^ Schneider and Buffard, Rec. med. veter., December 15, 1902, pp. •jii-yij.
^ Dr. Billet has lecently confirmed this statement in a letter to us. None of
the strains of trypanosome which he found was infective for the mouse.
^ In so far as the diagnosis is concerned, we may remark that it had been made
with certainty in 1894 by the veterinary officer Busy. It was only in 1899 that
Busy, doubtless owing to the discovery of other trypanosome diseases, expressed
slight doubts about his earlier diagnosis in a report which Schneider and Buffard
have made public. On reading the two successive reports of Busy (in Schneider
and Buffard, /(?(;. cit., pp. 726, 727), one finds that the horse was ill at least three and
a half months before death, that it had cedema of the sheath and scrotum, swelling
of the mucous membrane of the urethra and of the glans penis; 'well-defined,
rounded, prominent plaques' on the flanks and hind-quarters (first report ; in the
second report Busy mentions only slight staring of the coat), and no fever. All
these symptoms would point to dourine rather than to malde la Zusfana (see p. 211),
in which there are no cedematous swellings.
^ Rouget, Rec. nicd. vetcr., February 15, 1903, pp. 81-90.
DOURINE 329
' I inoculated three mice with blood from a rabbit with dourine,
and on the sixth day two of the mice showed a few trypanosomes in
their blood. One of these animals recovered, but the other became
very ill, so that on the fourteenth day, seeing that it was dying, I
killed it in order to collect some blood. It contained the trypano-
some in enormous numbers.
' I had on several previous occasions injected the blood of this
mouse into six other mice, without any of them showing the parasite.
The day the animal was killed I reinoculated them all, and in
addition inoculated four fresh mice. Three days later I found a few
trypanosomes in the blood of three of the newly-inoculated mice
and of one of those reinoculated, but instead of increasing in number
the parasites rapidly disappeared !
' Since then I have inoculated twelve fresh mice — both intra-
peritoneally and subcutaneously — with large doses (as much as 2 c.c.)
of blood taken from rabbits dying of dourine, but without result !
This blood was nevertheless infective, for it gave the disease to
rabbits and dogs.
' I have, therefore, been the victim of a particular instance of in-
dividual susceptibility, and Rouget's hj'pothesis still remains to be
proved.'
In their recent review of the trypanosomes,^ Rabinowitsch and
Kempner state that, starting with a trypanosome of dourine (obtained
from Nocard, who got it from Schneider and Buffard), which was
not at all virulent for rats or mice, after more than ten passages they
succeeded in infecting white rats. They do not give any other
details.
Finally, Rouget has recently published the results of further
experiments upon rats and mice with a trypanosome from a stallion
in the remount dep6t at Blidah, which confirm in every detail the
earlier results he obtained in 1896.^
To summarize, then, we see that the trypanosomes of Rouget
killed all white and grey mice, all white rats, and a certain per-
centage of sewer rats ; that the trypanosome of Schneider and
Buffard, in Nocard's hands, killed a series of rats and one mouse,
and gave a mild and temporary infection to other mice, but finally
was without eifect upon numerous rats and mice ; while in the hands
of Rabinowitsch and Kempner this same trypanosome was rendered
virulent for the rat.
As a result, we think that Rouget was dealing with the trypano-
some of dourine^ and, so far as the susceptibility of rats and mice is
■ Rabinowitsch and Kempner, Centralb.f. Bakter., I, Orig., v. 34, 1903, p. 815.
^ Rouget, C. R. Soc. Biol., v. 56, iVIay 7, 1904, p. 744. According to Rouget,
there can be no doubt about the diagnosis of dourine in this BUdah stallion, for it
was proved experimentally. A gelding was inoculated with the blood of the
stallion, and the progress of the disease thus transmitted was followed step by step
by the veterinary officer Chenot.
^ [This has been confirmed by Mesnil and Rouget's experiments, described
later. J
330 TRYPANOSOMES AND THE TRYPANOSOMIASES
concerned, we are of opinion that it varies with the strain of trypano-
some (for there maj' be several varieties of dourine), with the species
of animals through which the parasite has been passed, and with the
rats and mice used.
[Ligni&resi has made some observations upon rats with the Schneider-
Buffard trypanosome of dourine. At first the rats died in about two
months, but after a series of passages they died, with some exceptions, in
five to six days. This confirms the results of Rabinowitsch and Kempner
with a virus obtained from the same source.]
[Mesnil states that this virus, after passage through rats — given him
by Rabinowitsch — kills mice in about six days. Ligniferes' exalted virus
killed all the horses and dogs experimented upon ; rabbits, however,
recovered after a year.]
[Thomas and Breinl inoculated twenty-three rats with large numbers
of the parasite ; only two showed trypanosomes in their blood, and these
rats died in eleven and eighteen days.]
[As in caderas and, to a less extent, in nagana, mice injected with the
blood of another mouse undergoing treatment with trypanred become
infected after a very long incubation period (Halberstaedter). Thus in
one experiment it was found that the incubation period was four weeks,
but the course of the infection was not otherwise altered, and the mouse
died two days later.]
According to Nocard {Biologic, igoi, p. 465), 'all species of
ruminants appear to be absolutely refractory to dourine, as do also
the macaque monkeys.' [Subsequent observations have shown,
however, that this is not the case. Pease ^ inoculated two buffaloes
with virulent blood containing the trypanosome of Indian dourine,
and in both cases observed local swelling and multiplication of the
parasite at the site of inoculation. One buffalo was reinoculated
three months after the first injection, and trypanosomes were again
found at the site of inoculation. A third injection, of 100 c.c. blood,
given a month after the second, produced no effect in three months,
so that the buffalo had probably become immunized. The animal
was then injected with surra, and T. evansi was present in its blood
on the twelfth day.]
[Pease also inoculated a sheep and a goat with dourine, but un-
successfully. Thomas and Breinl likewise failed to infect a goat
with this trypanosome.]
[Mesnil and Rouget,^ having obtained an exalted virus, repeated
Nocard's experiments upon ruminants and monkeys, and found both
these species susceptible.]
[A goat was injected subcutaneously with the blood of a mouse infected
with Rouget's (1904) trypanosome. On the eighth day and at intervals
during the first two months after inoculation a few trypanosomes were
seen in blood-films. The goat's blood was still infective (on injection)
' [Lignieres, Report io Pathological Sectioti of Eighth Congress of Veterinary
Medicine, Budapest, September, 1905 ; abstract by Mesnil, Bull. Inst. Past.,
V. 3, p. 946.]
2 [Pease, Vet.Joiirn., v. 10, 1904, p. 297.]
3 [Mesnil and Rouget, Ann. Inst. Past, v. 20, 1906, p. 689].
DO URINE 331
sixteen months after the animal was inoculated. Nineteen nionths after
inoculation the goat was still alive, but then became blind fairly rapidly,
and a fatal termination seemed probable. As sometimes happens in equine
dourine, there were periods of temporary improvement simulating recovery.
One of the mice inoculated with the blood of this goat died in sixty-two
and a half days, after passing through a stage of apparent cure. Four
dogs out of five inoculated developed blindness.]
[A Breton cow, inoculated at Alfort by Vallee with the same virus, also
became infected, the infection lasting several months. The cow became
immunized, for a reinoculation made six months after the first failed to
reinfect the animal.]
[A young goat ( ^ ) was inoculated with the original Schneider-Buffard
virus made virulent for rats by Rabinowitsch. A very mild infection
followed, which lasted about six months. The goat recovered and acquired
immunity, for a fresh inoculation with the same virus produced no effect.
Three months after the second inoculation the goat was injected with the
Rouget virus, and was found to be immune against this, as well as against
the original Schneider-Buffard trypanosome. This experiment proves the
identity of the parasites found in horses having the symptoms of dourine.]
[The monkey inoculated by Mesnil and Rouget was a large
Macacus cynomolgus. It was injected with the Rouget virus, and
had a severe infection lasting three to four months, with rises of
temperature — to 40° C. (104° F.) or above on several occasions,
generally coinciding with exacerbations in the numbers of the
parasite. The animal died five months after inoculation, but it had
apparently recovered from its trypanosome infection.]
In 1896 Rouget stated that 'guinea-pigs were refractory at all
ages and under any conditions,' but with a trypanosome derived
from another source in 1904 all his guinea-pigs became infected
(personal communication).
[Rabinowitsch and Kempner succeeded in raising the virulence
of the trypanosome of Schneider and Buffard, by passage through
white rats, so that it became pathogenic for rats and also for guinea-
pigs. Thomas and Breinl inoculated four guinea-pigs and a cat, but
with negative results.]
Refractory Animals.^ — ' Birds — fowls, pigeons, and sparrows
— and bats are refactory, no matter how many trypanosomes be
injected, or what mode of inoculation be employed. Fowls and
pigeons, cooled in the ordinary way, were found to be absolutely
immune . . .'
' Cold-blooded animals — snakes, lizards, frogs — are insusceptible.
Frogs placed in the incubator at 37" C. were inoculated on several
occasions in the dorsal lymph sac ; but the parasites never multi-
plied, and no trace of them could be found after thirty-six hours '
(Rouget).
1 [Bergeret and Benin {Lyon medical, v. 104, 1904, p. 622) record a case of
dourine in a man who is supposed to have contracted the disease through sexual
intercourse with a mare. On reading their account of the case it is seen that there
is no proof that the man really had dourine ; the symptoms were urethral dis-
charge, enlarged glands, and general weakness. Trypanosomes were never looked
for in the man, nor were they found in the mare.]
332 TRYPANOSOMES AND THE TRYPANOSOMIASES
Section 4. — The Trypanosoma equiperdum.
We certainly have less information concerning the morphology
and biology of the trypanosome of dourine than we have of any of
the other well-known pathogenic trypanosomes.
Rouget's report of 1896 contains several figures giving a good
general idea of the parasite as it appears in the living state ; but at
that time the methods of staining were insufficient to bring out the
distinctive points in the morphology of these parasites.
In their papers published in igoo Schneider and Buffard give a
large number of figures of the trypanosome, accompanied by a long
description, but both figures and text are lacking in precision.
These authors certainly saw small agglutination rosettes, and pos-
sibly, too, forms dividing longitudinally. Since then Schneider and
Buffard have not again referred to the morphology of their trypano-
some. In their ' Treatise on Micro-biological Technique,' published
in igo2, Nicolle and Remlinger give, on p. 897, some of Schneider's
figures, which are more detailed copies of some of the drawings in
his paper of 1900. These figures show five stages in the longi-
tudinal division of the parasite, closely resembling those we had
given a year previously for the trypanosome of nagana.
Thanks to Nocard and Schneider, we were able, in the year 1900,
to study the trypanosome of dourine in the blood-stained oedema
fluid of the horse and dog, and have, on two occasions, given an
account of the morphology of this parasite {Biologie, November 17,
1900, and March 23, 1901), showing, among other things, that its
mode of longitudinal division is identical with that of T. brucei, and
that it differs from the latter trypanosome in several details.
Fig. 44 is drawn from our preparations made at that time.
In their paper of October, 1903, Rabinowitsch and Kempner give
four coloured figures of T. equiperdum, but none of them shows any
dividing forms. Since 1900 we have had the opportunity of studying
this trypanosome in the blood of Nocard's mouse (see p. 329), and of
other mice obtained from Rouget.
In ordinary fresh preparations the trypanosome of dourine
resembles the other pathogenic trypanosomes. Like them, it
scarcely moves except in loco, but it is quite easy to make out that
it can move from place to place, the flagellum being usually, but by
no means always, foremost.
In films made from the blood-stained oedema fluid of the dog or
horse, and stained by our ordinary method, the parasite has the
appearance given in Fig. 44. The centrosome is always very distinct,
and is exactly the same as in T. brucei and T. evansi, while the
undulating membrane is almost as much folded as in those trypano-
somes. The nucleus is centrally situated, and the free flagellum is
about as long as in T. brucei. The posterior extremity may vary
considerably in form, and sometimes it seems to present two points,
DO URINE
333
as seen in Fig. 44, 2, j. This part of the parasite is undoubtedly
very contractile, but apparently a little less so along the edges than
in the middle.^
The protoplasm stains fairly uniformly, but perhaps a little less
deeply than in the case of the other pathogenic trypanosomes. In
this respect T. equiperdum is rather like T. lewisi. The protoplasmic
granules seen in T. briwei and others are never seen in this trypano-
some, which is an important distinguishing feature, for it appears to
be a constant one. Schneider has also noticed this point, and as
these granules are present in the trypanosomes found in horses
suffering from mat de la Ztisfana (see p. 211), he regards those
trypanosomes as different from T. equiperdum.
Lastly, we should draw attention to the precentrosomic vacuole
seen in Fig. 44, ^. This resembles the vacuole, similarly situated,
Fig. 44. — T. equiperdum.
Ordinary form, not undergoing division. 2, 3. Stages in binary fission.
with vacuole.
4. Form
which is found in T. gambiense occurring in the cerebro-spinal fluid
in sleeping sickness. Its causation is undoubtedly the same in both
cases. It is difficult to fix the trypanosomes perfectly in any of the
body fluids other than pure blood. ^
The parasite is 25 /x to 28 /j, long, even in the horse, and is there-
fore a little shorter than T. bnicei ; it is also slightly narrower.
Fig. 44, 2, J shows two stages in longitudinal binary fission,
which takes place in the usual way.
As we have already mentioned, the above remarks refer to the try-
panosome of Schneider and Buffard, as found in the dog and horse.
In the blood of the mice we have examined the trypanosome is
slightly different. For example, in Nocard's mouse the parasites
are more stumpy than those we have just described, and the proto-
1 [Dr. Woodcock suggests that the bifid appearance of the posterior extremity
may possibly be due to commencing division, for in both cases figured (s andj)
division had begun.]
2 [.'\s previously stated (Chapter III.), I am not entirely in agreement with the
authors on this point. In Uganda, trypanosomes in blond-fi\vns of human beings
and of animals infected with T. gambiense often showed a precentrosomic
vacuole.— Ed.]
334 TRYPANOSOMES AND THE TRYPANOSOMIASES
plasm contains a number of large granules. Possibly the trypano-
somes showed these characteristics because the mouse was on the
point of dying when it was killed. In the blood of Rouget's
mice, taken a considerable time before death, these stumpy forms
were again met with, and the granules were also present, but they
were very scanty. In one specimen we saw a trypanosome with six
nuclei, two of which Were still dividing. We have recorded similar
forms in the case of T. brucei and T. equinum. Rabinowitsch and
Kempner {loc. cit., p. 812) talk of parasites with eight and ten nuclei
arranged in the form of a rosette. Possibly, too, one of Schneider
and Buffard's figures represents a similar case of multiple division.
[In Lingard's account of the trypanosome of Indian dourine he
states that this trypanosome contains fewer and smaller chromatic
granules than does T. evansi ; also that its undulating membrane is
less developed. Onlj' one mode of division — longitudinal fission —
occurs. This may begin at either end or in the middle.]
The systematic study of the morphology of T. equiperdum in the
various susceptible mammals is very necessary.
The few details we possess concerning the biology of this parasite
seem to show that it differs hardly at all from that of the other
trypanosomes.
' After escaping from the bloodvessels the parasite retains its
motility only for a few hours ; but we have seen it remain motile
for forty-eight hours, in a sealed preparation, kept at a temperature
of 36° C. After twenty-four hours, however, the blood of an infected
animal is no longer virulent ' (Schneider and Buffard).
So far as we are aware, the action of different serums upon
T. equiperdum has not been investigated.
[It has already been mentioned that Lingard found the blood and
blood-stained oedema fluid from a plaque microbicidal in vitro, causing
loss of motility and granular degeneration of the trypanosomes. We
shall also see later (Section 7) that Rabinowitsch and Kempner
found human serum, as well as the serum of immunized rats,
microbicidal.]
[Jakimoif and Nina Kohl^ have made some observations upon
the vitality of this trypanosome in corpses, and the former^ has, in
addition, studied the vitality of T. equiperdum under conditions
similar to those previously used by him for T. brucei and T. eqidnuni
(see pp. 157 and 305).]
[Mice that had died of dourine showed motile trypanosomes thirty
hours after death when the body was kept at a temperature of 2'5° to 5°C.
above zero. No living trypanosomes were found after eighteen hours if
the corpse was kept at the room temperature.]
[The vitality of T. equiperdum was also tested under the following
conditions: (i) In defibrinated blood; (2) on adding citrate solution;
and (3) on adding horse serum ; and in each of these cases the trypano-
^ [Jakimoff and Nina Khol, Arch, des Sc. Biol. (Russes), 1906, Nos. 4, $.]
2 [Jakimoff, C. R. Soc. Biol., v. 5i, 1906, p. 631.]
DOURINE 335
somes were kept at different temperatures: 4° C. to zero, room temperature
(21° C), and 32-5° C. The trypanosome was found to retain its virulence
longest (three days) when mixed with the citrate and kept in the refrigerator.
The virulence was retained for two days in the defiibrinated blood, and for
only one day after the addition of horse serum. In every case the virulence
was tested by injecting white mice. The incubation period was always
increased ; instead of three to four days, it was eight to thirteen days.]
[On comparing the three trypanosomes, it is seen that T. bnicei and
T. equinum are much more resistant than T. eguiperdum. The first two can
survive for six days under certain conditions, and the best media for them
are defibrinated blood and horse serum. Nor is the optimum temperature
the same ; T. brucei and T. equinum survive longest at the room temperature,
T. equiperdum at, or just below, zero.]
Schneider and Buffard figure a rosette of five parasites united by
their posterior ends. Rouget has observed that when the trypano-
somes are very numerous in the blood of mice, ' they occur in thick
clusters,' and we have noticed the same thing.
[Cultivation of T. equiperdum. — Thomas and Breinl have made
several attempts to cultivate this trypanosome, with slight success.
Two tubes of a modified Novy and McNeal's medium, the same
as that used for T. equinum (see footnote, p. 306), out of nineteen
inoculated with the blood and oedema fluid of a puppy, showed
motile trypanosomes on the eleventh day. On the seventeenth day
one of the cultures showed many dividing forms which were
agglomerated into clumps, but no rosettes were seen. There were
also many single parasites, but their motility was much diminished.
On this date, the seventeenth day, the culture was still pathogenic]
Section 5. — The Individuality of Dourine.
As we have seen, the trypanosome of dourine differs only slightly
from the other trypanosomes of the type brucei; but it is particu-
larly scanty in the blood of infected Equidag.
From the point of view of its clinical course in the Equidae,
dourine resembles the other animal trypanosomiases in some
respects, but differs from them in others. The points of resem-
blance are the following : the anasmia, the fever, the swellings
affecting especially the genital organs and the dependent parts of
the body, the lesions of the eyeball and eyelids, the wasting — in
spite of a normal or even an increased appetite — and the muscular
weakness, especially of the hind-limbs. The chief points of differ-
ence are : the duration of the disease, the presence of the cutaneous
plaques, the symptoms of paralysis of the hind-quarters associated
with the presence of patches of softening in the spinal cord, and the
long afebrile periods which follow the initial rises of temperature.
The characteristic features of dourine are not constant — the
cutaneous plaques, for example, are usually absent in the donkey —
and in the horse they may be regarded as having some relation to
the very chronic course of the malady, for in the subacute cases they
336 TRYPANOSOMES AND THE TRYPAXOSOMIASES
dp not occur. Nocard (vide supra) was able to kill horses in four to
eight weeks, and the temperature in those cases was exactly as in
surra or nagana. On the other hand, we have seen that some Togo
horses did not succumb for nearly a year to a trypanosomiasis closely
allied to nagana.
In the Equidse dourine behaves, then, like an attenuated form of
nagana, and the same may be said of its behaviour in the ordinary
laboratory animals — dogs, rabbits, rats, and mice. In rabbits this
resemblance is particularly marked. The lesions of the eyes, genital
organs, and skin in rabbits suffering from dourine, so closely
resemble the lesions produced by nagana or caderas as to be indistin-
guishable from them. The only difference is that in dourine the
progress of the disease is much slower. In nagana the rabbit never
lives longer than two months after inoculation, whereas in dourine
the animal may live for six months with the characteristic symptoms,
and may even recover.^
[It has been stated that] many animals susceptible to nagana and
to the allied trypanosomiases are refractory to dourine, such as
macaque monkeys (according to Nocard), goats, sheep, and cattle.
It will be remembered, however, that all these mammals, except
perhaps monkeys, are less susceptible to nagana than the ordinary
experimental animals. Cattle suffer, as a rule, only slightly in surra,
and in mal de caderas are not ill at all, yet we have seen how closely
these two epizootics resemble the African diseases which are pro-
pagated by tsetse-flies or other biting insects.
[The observations of Pease and of Mesnil and Rouget establish-
ing the susceptibility of ruminants and monkeys to the virus of
dourine, bring this trypanosome into line with the other pathogenic
mammalian trypanosomes. Injections into these species of animals
can, therefore, no longer be relied upon in diagnosing dourine from
allied trypanosomiases, as is frequently necessary in Algeria, India,
and elsewhere. Pease has shown that the pariah dogs in Lahore
are very resistant to dourine, but susceptible to surra, while ordinary
dogs are susceptible to both diseases. This might be utilized as a
means of diagnosis, and, moreover, tends to show that surra and
dourine are distinct diseases.]
So far as the aetiology is concerned, dourine stands alone, for
infection occurs by coitus. That may be due simply to the fact that
the trypanosome can pass through healthy mucous membranes.
The Sergents' comparative experiments on this point with the
trypanosomes of dourine and of debab (see p. 219) are interesting,
and show that these two Algerian trypanosomiases are distinct
morbid entities.
That flies cannot play any part in the propagation of dourine is
certain, and may be due to the absence of the appropriate carriers
of the infection from countries in which the disease is prevalent, or
^ [Lignieres' rabbits recovered after a year. See p. 330.]
DOURINE iz7
to the fact that very few parasites are present in the blood of infected
animals. It would be interesting to know what the aetiology would
be in a country in which the tsetse is found.
[Lingard, in his paper on ' Dourine and its Trypanosome,' to
which frequent reference has been made, says that flies (sp. ?)
can convey the trypanosome of dourine and produce infection in
healthy susceptible animals. There is no evidence at present, how-
ever, that flies act as an intermediate host.]
The following experiments point clearly to the individuality of
dourine. Nocard {Biologie, May 4, 1901, p. 466) inoculated with
nagana a control dog and two other dogs highly imrnunized against
dourine. Whereas the control dog lived for fourteen days, the two
dogs which were refractory to dourine died in eleven days. Later,
Lignieres^ made an analogous observation by inoculating the para-
site of caderas into two dogs immunized against dourine. These
dogs succumbed to caderas in about one and a half months, whilst
the controls lived about two months.
From these facts it can scarcely be doubted that animals im-
munized against dourine are susceptible to the other trypano-
somiases — to surra, for example. We may therefore conclude that
dourine is a definite morbid entity.
[Other, more recent, observations confirming this conclusion as
to the specincity of dourine are those of Pease, who immunized a
buffalo against dourine and then found it susceptible to surra, and
of Mesnil and Rouget, who immunized a goat against the virus of
Schneider and Buffard and then found it insusceptible to the virus
of Rouget. The latter result proves the identity of the parasites
found in horses suffering from dourine in different parts of the
world.]
Section 6. — Mode of Propag-ation.
Dourine is transmitted by coitus. [In this respect, as well as in
several others, it resembles syphilis. The virus m both cases has
the power of penetrating intact mucous membranes. Dourine is due
to a specific trypanosome, while syphilis is almost certainly caused
by the Treponema pallidum of Schaudinn, and, as was stated in
Chapter III., a trypanosome stage in the life history of this parasite
has been described by Krzysztalowicz and Siedlecki. Like syphilis
in man, dourine may run a very chronic course in horses (two years
or more), and the lesion found in dourine in the lumbo-sacral region
of the cord to some extent resembles a localized syphilitic meningo-
myelitis (Mott).] .
Before we knew anything about the pathogenic agent of the
disease, ' the experimental proof of this mode of transmission (by
coitus), previously given by Hertwig, was again furnished by Prince
^ Lignieres, Riv. Soc, med. argent., v. 10, 1902, pp. 112-L14.
22
338 TRYPANOSOMES AND THE TRYPANOSOMIASES
and Lafosse in 1861-1862. Of fifteen healthy mares which were
covered by four diseased stallions, ten became infected — five of them
severely — while five remained well. Two healthy stallions which
served the infected mares contracted the disease. Trasbot in 1877
and Peuch in i8g8 gave the disease to mares by allowing them to be
covered by stallions suffering from dourine.
' Numerous observations show that an infected stallion transmits
the disease to the majority of the mares covered by it, and during
the whole of the breeding season. One may say that two-thirds or
three-quarters of the mares exposed to infection become contami-
nated ' (Nocard and Leclainche, p. 626).
These observations have been confirmed and explained since the
discovery of the pathogenic agent, for we have seen that the trypano-
some of dourine can pass through healthy mucous membranes, and
so give rise to the disease. The disease produced experimentally in
horses, dogs, and rabbits by any artificial method, such as sub-
cutaneous inoculation or placing the virus upon a mucous surface,
may be transmitted from one sex to the other by coitus. Rouget
was the first to show this, and since then Schneider, Buffard, and
Nocard have recorded a large number of similar observations.
Rabinowitsch and Kempner {loc. cit., p. 808) state that they
succeeded in transmitting dourine from rat to rat (of the same sex)
by means of fleas.
Is coitus the only natural mode of transmission of dourine in
the Equidae ? ' Infection apart from coitus is extremely rare, and
doubtless always results from direct infection. The cases observed
in geldings or in old mares were due to an infection of the genital
mucous membrane through the medium of grooming instruments, such
as sponges, or by means of litter ' (Nocard and Leclainche, p. 626).
Section 7. — Treatment. Immunity. Prophylaxis.
Treatment. — ' Treatment with arsenic is alone of any value.
Trelut obtained good results with arsenious acid (3 to 6 grammes
a day), either alone or in conjunction with oil of turpentine or
reduced iron (6 to 9 grammes). Blaise also recommends arsenious
acid or arseniate of soda, together with arseniate of strychnine.
' Arkhangelsky and Novikoff cured stallions of dourine by sub-
cutaneous injections of sodium arsenite or cacodylic acid ' (Nocard
and Leclainche). Marchal,^ veterinary officer at Constantine, states
that he cured five stallions of dourine by injecting them sub-
cutaneously with cacodylate of sodium in doses of i gramme in
5 c.c. water on five consecutive days, followed by five days without
injections. The duration of the treatment varies ' with the resistance
of the animals, and with the extent to which the trypanosomes are dis-
tributed throughout the body.'
1 Marchal, Rev. me'd. vcta:, April 15, 1903, p. 230, and April 15, 1904, p. 231.'
DOURINE 339
[Pease,! in India, also tried the effect of injections of cacodylate
of soda, but did not obtain the successful results Marchal had done.
An animal treated by Pease in this way had bouts of fever, oedema,
plaques, and trypanosomes, just like an untreated animal. Pease
concludes that the successful results quoted by Marchal in his second
paper were probably chronic cases which were recovering spon-
taneously, and in which the arsenic acted as a tonic and alterative
rather than as a parasiticide.]
It is naturally interesting to compare these results with those
obtained by means of arsenic in the treatment of the other trypano-
somiases.
We have tried the effects of trypanred upon mice infected with
the trypanosome which we obtained from Rouget. This drug has
a very definite effect, but more or less quickly relapses occur, which
are, however, amenable to further treatment with the drug.
Rabinowitsch and Kempner (loc. cit., p. 8io) write as follows :
' According to our observations, not only human serum, but also in
some cases the serum of white rats actively immunized against
T. lewisi, as well as of passively immunized rats, have a microbicidal
action upon the trypanosome of dourine.'
Rouget made certain experiments in serum-therapy. He used
the serum of rabbits or dogs in the last stage of the disease when
cachexia had begun to develop. This serum mjected into mice —
after demonstrating the presence of the parasite in the blood by
means of the microscope, two or three days after inoculation — did
not materially prolong the life of the animals, for they survived the
injection only from three to seven days. The therapeutic effect of
this serum is therefore insignificant.^
Prevention. — ' Employed as a prophylactic in doses of J c.c, the
same rabbit serum prevented the excessive multiplication of the
trypanosomes in six mice. These mice survived, although on several
occasions one was able to demonstrate the presence of the parasite
in the blood from the tip of the tail — one or two parasites in each
field of the microscope. All the other mice so treated lived only for
a short time, varying from seventeen to twenty-three days. The
results were the same whether the virus and the serum were injected
after mixing in vitro or separately ' (Rouget).
These facts quite agree with our own observations upon the
serum of goats or sheep suffering from nagana or caderas.
' The serum of animals naturally refractory (pigeon, fowl) does
not possess any immunizing properties, even though the animals be
previously inoculated with large doses of infective blood ' (Rouget,
P- 727);
This is again similar to what we found in the case of T. brucei.
^ [Pease, Vet. Journ., v. 9, 1904, p. 196, and v. 12, 1905, p. 209.]
^ [Baldrey states that castration performed in the first stage of the disease
seems to benefit some cases. Forrecent experiments on treatment see Chapter XIII.]
22 — 2
340 TRYPANOSOMES AND THE TRYPANOSOMIASES
Immunity. — Animals suffering from dourine (horses or experi-
mental animals) enjoy a certain amount of local imm.unity, for ' they
show no signs of local reaction on reinjecting them with large doses
of the virus ' (Schneider and Buffard).
' Several dogs recovered after having been extremely ill, and were
then quite immune, for on injecting them with enormous doses of
infective blood or oedema fluid they did not react in the slightest '
(Nocard, Biologic, May 4, 1901, p. 466).
[In the foregoing pages other instances of local and general
immunity have been mentioned. Thus, a buffalo inoculated by
Pease on three successive occasions showed a local multiplication of
trypanosomes after the first two injections, but then appeared
immunized against dourine, for the third injection had no effect.
The buffalo was normally susceptible to surra, however.]
[Mesnil and Rouget immunized a kid against Schneider and
Buffard's virus, and found it also immune against Rouget's virus.
Valine immunized a cow against Rouget's virus.]
Prophylaxis. — -The prophylaxis of dourine is a priori a simple
matter. There is no advantage in killing infected animals, as in the
case of the other animal trypanosomiases ; but it is sufficient to make it
impossible for them to propagate the disease by the ordinary method.
The indication, therefore, is to castrate all stallions suffering from
dourine, and in the various countries where the disease occurs this
is made compulsory. In the case of mares it is safer to kill them
when diseased. In the parts of Algeria under civil administration
the mayors or other responsible officials have the right to enforce
this slaughter. But in order to apply the laws and regulations
concerning dourine, it is necessary to be able to diagnose the disease.
Whereas in horses the fully-developed disease is generally easy to
diagnose, this is often difficult in the earlier stages, and in the
donkey diagnosis is always difficult. The micro-biological method may
be of the greatest assistance in the diagnosis. One should examine
the cedema fluids microscopically for the parasite, and if it is not
found, then one should inject into a dog a large dose of oedema
fluid or, failing this, of the blood of the suspected animal.
By sanitary inspections alone it has been found possible hitherto
to prevent the introduction of dourine into France from Algeria or
from Navarre, where the disease is endemic. Suspected animals are
effectively prevented from reproduction.
[But, as has already been stated in Section i, Schneider and Buffard
maintain that in France dourine appears nearly every year in the
department of Basses- Pyrenees, on the Spanish frontier. Mares get
infected by the asses or horses by which they are covered. As is also the
custom of the Arabs in Algeria, a mare is first covered by an ass, and if
not impregnated, she is then served by a stallion. The asses operate on
both sides of the frontier, and in this way introduce the disease into France
from Spain.]
In Algeria prophylaxis is not such a simple matter. ' The male
DOURINE 341
donkey propagates the disease by carrying the trypanosome, while
the female helps to preserve the parasite. It is the ' roving ' male
which, by means of clandestine intercourse, is responsible for all the
outbreaks of dourine. In the mule-rearing districts he infects the
mares covered by him ; then, if these mares are not fecundated —
which one can tell in May — they are allowed to be covered by
stallions, which, in their turn, become infected by the mares, who
at the time of pairing show very few, if any, symptoms of the
disease. In this way is to be explained the periodic appearance of
dourine in the Government studs at the end of May and during the
first fortnight of June — that is to say, during the last month of the
pairing season' (Schneider and Buffard).
The problem to be solved is a difficult one — namely, to restrict
all intercourse to asses officially recognised as healthy.
Appendix.
'Maladie de Soemedang"' (Java).
The following details about this disease are taken from Nocard
and Leclainche's treatise (v. 2, pp. 584, 585) :
' In February, igoo, Hubenet discovered in the Government stud at
Soemedang a disease among the stallions which was conveyed by coitus
to the native mares. This disease was somewhat like surra, which, as we
have seen, occurs in other parts of Java, but more like dourine. An
infected horse sent to the laboratory at Weltevreden was made the subject
of investigation by de Does.i The "maladie de Soemedang" is characterized
by swelling of the genital organs, following upon an infecting coitus,
accompanied usually by purulent catarrh of the mucous membrane. The
swelling extends along the abdominal wall and reaches the chest. White
patches occur in the skin, around the genital orifices, and on the perineum.
Urticarial swellings occur, and these are followed by progressive atrophy
of the muscles and paresis of the hind-quarters. If the disease progresses,
complete paralysis occurs, and the animals die. Death is the usual
termination with stallions, but mares often recover. The only lesion
found, apart from those in the genital region, is softening of the spinal
cord, which is surrounded in the lumbar region by a gelatinous deposit,
which also infiltrates the sciatic nerve.
' The blood-stained cedema fluid obtained from the swellings of the
genital organs contains a few trypanosomes, but the parasites have never
been seen in the blood. In appearance they resemble T. evansi.
' Rabbits inoculated subcutaneously with ^ to 5 c.c. of the oedema
fluid die, much emaciated, in from thirteen to twenty-five days. The only
symptom is catarrhal conjunctivitis, and sometimes some paresis before
death. Trypanosomes could never be found in the blood, yet the blood
was infective for another rabbit when injected in large doses (3 c.c).
The dog inoculated subcutaneously or by scarification did not show any
symptoms for four to six weeks.-
' Two guinea-pigs remained free from infection after subcutaneous
' J. de Does, ' Boosaardige deksiekte in het Soemedangsche,' Third Report,
Veeartsenijktindige Bladen voor Nederl.-Indie, v. 14, igoi, pp. 20-45.
2 The ten dogs inoculated all died from a severe infection by ankylostomes.
342 TRYPANOSOMES AND THE TRYPANOSOMIASES
injection of ^ c.c. blood. De Does thinks that the " maladie de
Soeniedang " differs from both surra and dourine. So far as the dis-
tinction from dourine is concerned — which need alone be discussed — the
author points out that the Java disease is by no means always fatal ; the
lumbar hyperaesthesia and the arching of the back are absent, the swelling
of the lymphatic glands is nearly always absent, and the results of animal
experiments are different. De Does thinks it may be a variety of dourine
which has undergone some evolutionary change. This conclusion, which
seems to follow from the facts stated, would have more weight if supported
by more extended and more exact experimental investigations.'
CHAPTER XI ■
GALZIEKTE (GALL-SICKNESS)
Pathogenic Agent : Trypanosoma theileri, Laveran, Bruce, 1902.
Galziekte or gall-sickness is a disease of Bovidse endemic through-
out a large part of South Africa, due to a trypanosome which, both
morphologically and in its pathogenic action, is quite distinct from
the parasites we have hitherto studied.
Section 1. — Historical. Geographical Distribution.
According to Theiler,^ this disease was described for the first time
by the veterinary surgeon Spreull, and the epizootics described by
Kolle under the name of malaria of cattle,^ and by Hutcheon, the
principal veterinary officer of Cape Colony, under the name of
jaundice or biliary fever, ^ were really gall-sickness.
The disease is generally called gall-sickness or galziekte by the
farmers in South Africa, but under the general designation of
' biliary diseases ' several different diseases of cattle have been
confounded.
Gall-sickness often occurs at the same time as the bovine piro-
plasmosis or redwater fever of the Transvaal. Theiler draws attention
to the fact that the name gall-sickness has been used in the Transvaal
since 1871, before the disease redwater was known there, and that
even at the present day gall-sickness is met with in parts of South
Africa where redwater has never occurred.
The trypanosome which is the causal agent of gall-sickness was
discovered by Theiler, and described by one of us and by Bruce
almost simultaneously, under the name of T. theileri.^
Gall-sickness is prevalent over a large part of South Africa. It
has been observed among the cattle in Zoutpansberg in North
Transvaal, in the valley of the Komati in the east, in the neighbour-
hood of Standerton in the south, and in Klerksdorp in the west,
1 A. Theiler, 'A New Trypanosoma,' _/(?z^r«. Comp. Path, and Therap., 1903,
V. 16.
- Kolle, Zeiischr.f. Hyg. u. Infectionskrankh., 1898, v. 27, p. 44.
' Hutcheon, Report for 1897, quoted by Theiler, op. cit.
* Laveran, Acad, des Sciences, March 3 and November 3, 1902 ; Bruce, Lancet,
March 8, 1902, p. 664.
343
344 TRYPANOSOMES AND THE TRYPANOSOMIASES
as well as in cattle coming from Cape Colony and the Orange River
Colony.
The same trypanosome was also found by Theiler in Pretoria,
in the blood of an ox coming from Madagascar ; but the animal had
been some time in Natal before it arrival in the Transvaal.
Schilling has seen an identical trypanosome in a Togo ox.^
Panse^ found a very large trypanosome in the blood of a calf on
the island of Mafia, German East Africa. This trypanosome was
40 fj, to 80 fx long, not including the free flagellum, which itself
measured 30 f^. The posterior end was very pointed. Panse
expressed some doubt about the identity of this trypanosome with
T. theileri.
[Koch and Luhe, on the other hand, think that it is certainly
T. theileri. Koch has met with the disease in cattle coming from
Mafia Island, and also among cattle at the experimental station in
Rhodesia.^]
In the blood of an animal suffering from the ' Jinja ' disease
(see p. 205) Nabarro* found a trypanosome closely resembling, if
not identical with, T. theileri. This trypanosome was 44 /x long,
including free flagellum 18 /i, and had a very pointed posterior
end, a single nucleus, and two centrosomes. The other trypano-
somes found in this blood-film were either very short and stumpy
(length 13 yti, free flagellum 2 to 3 fj), or fairly long (length 20 jj, to 25 /x,
free flagellum 8 h to 10 /i). The animal probably had a double
infection, with T. dimorphon and T. theileri. These observations of
Panse, Koch, and Nabarro show that T. theileri has a wider distribu-
tion in Africa than was formerly supposed.*]
[Liihe^ and Luhs^ have also met with this trypanosome in
Bovidae in Transcaucasia. Liihe studied the morphology of the
parasite in stained blood-films sent to him by Ziemann, while Luhs
was able to make a study of the disease and of its trypanosome on
the spot. He observed it in six animals sick with cattle-plague —
that is to say, under the same conditions as Theiler did in South Africa
and Holmes in India. He never found it in other cases — for example,
in animals with piroplasmosis. The trypanosome was only feebly
pathogenic, for the blood of the sick animals could be used without
harmful effects, for immunization against cattle-plague.]
1 SchWWng, Journ. Trap. Med., 1903, p. 47.
- O. Panse, Zeitschr. f. Hyg., v. 46, 1904, p. 376.
^ [Koch, Lecture before Berlin Medical Society, translation in Brit. Med.
Journ., 1904, II, p. 1446.]
■* [Nabarro and Greig, Report of the Sleeping Sickness Commission, No. V,
1905, see p. 18 and Plate I, Fig-, i.]
" [Todd has recently described {Liverpool School Memoirs, 1906, No. XXI,
p. 9O a trypanosome which closely resembles, if it is not identical with, T. theileri,
found by Button and himself in the blood of an antelope killed at Kasongo, in the
Congo Free State.]
° [M. Liihe, in Mense's ' Handbuch der Tropenkrankheiten,' v. 3, 1906, p. 133.]
'' [F. Luhs. Arch. Parasitologic, \. 10, 1906, p. 171 ; abstract by Mesnil in Bull.
Inst. Past., V. 4, igo6, p. 91B.]
GALZIEKTE (GALL-SICKNESS) 345
[In India very large trypanosomes have also been observed in the
blood of cattle by Lingard and by Holmes. One of these, seen by
Lingard in the blood of cattle inoculated with surra, has already
been described in Appendix A to the chapter on Surra (p. 286).
Liihe states that Blanchard regards these Indian trypanosomes as
a distinct species, which he calls T. lingardi. Liihe himself is of
opinion that they are identical with T. theileri, and the evidence we
possess at present is certainly in favour of this view.]
[Durrant and Holmes, in their first paper, "^ state that they found a
trypanosome a little shorter than T. evansi in spleen smears of a bull post-
mortem, the animal having died after a fairly acute illness in the laboratory
at Muktesar. In a later paper ^ Holmes describes a very large trypano-
some which he found in the blood of ' hill ' cattle. The cattle in which
this trypanosome was seen were all more or less debilitated, or had been
inoculated with ' rinderpest ' serum. The ' plains ' breed of cattle never
showed trypanosomes. This trypanosome was 60 /u to 80 /i long (one
measured as much as 91 /i), free flagellum 15 /x to 25 fj. ; the width was
2 /i to 4 /i, in one case 6 jj.. The posterior end was very pointed, and the
centrosome was 10 /a to 17 /i from the tip.]
[Cattle seldom died of the infection unless they were very debilitated.
Inoculations into ponies, bulls, and rabbits gave negative results, so that
morphologically and in its behaviour in cattle and in experimental animals
this trypanosome closely resembles T. theileri. Holmes thinks that the
parasites previously seen by Durrant and himself in spleen smears were
immature forms of this trypanosome, but the figures they give illustrating
their paper do not warrant this belief. Many of the parasites depicted
look quite mature and normal in appearance, and resemble the surra
trypanosome.]
[Lingard^ describes a similar trypanosome which he discovered in the
blood of ' hill ' cattle in 1902. He calls it T. himalayanum,* but it probably
is the same parasite as that described by Holmes.]
[In the blood of ' plains' cattle, Lingard in 1895, during an outbreak
of surra, discovered a large trypanosome which he thinks may have been
T. theileri.^']
Section 2. — Gall-sickness is a Disease Peculiar to the Bovidae.
All attempts made by Theiler to infect with gall-sickness animals
other than Bovidje were unsuccessful. His experiments were made
upon horses, dogs, sheep, goats, rabbits, guinea-pigs, rats, and mice.
In Bovidffi infection occurs more or less easily, according to the
origin of the animals. Theiler states that the Transvaal cattle are
the least susceptible, and that cattle coming from Texas and the
Argentine Republic become infected in a much larger proportion
than do the native cattle.
The disease has been observed in animals of all ages.
"■ [Durrant and Holmes, Jaurn. Comp. Path, and Therap., v. 17, 1904, p. 209].
2 [Holmes, _/i7Kr«. Comp. Path, and Therap.., v. 17, 1904, p. 317.]
^ [Lingard, Indian Med. Gaz., 1904, p. 445.]
* [Lingard, yr9«r«. Trap. Vet. Sci., v. i, igo6.]
346 TRYPANOSOMES AND THE TRYPANOSOMIASES
Section 3.— Course of the Disease. Symptoms.
The disease may run an acute or a subacute course. Tiiree to five
days after inoculation ttiere is usually a rise of temperature, lasting
several days, after which the temperature falls again to normal. In
some cases the presence of the trypanosome appears to have very
little effect upon the health of the animals, but as a rule the infection
is accompanied by severe ansemia. In one case the red corpuscles
were reduced to 2,500,000 per cubic millimetre. Often basophile
granules are seen in the red corpuscles, but they are not character-
istic of this disease, as they are very common in bovine piroplas-
mosis (Theiler), and are usually found in all severe anaemias. As in
other grave anaemias, nucleated red corpuscles are frequently met
with. The leucocytes are increased in number in most cases.
The trypanosomes are often fairly numerous in the blood, but do
not remain present for long. The longest time that they were seen
in the blood was thirteen days, and the shortest one day, the average
being nine days. According to Theiler's observations,^ the number
of parasites does not appear to have much influence upon the
severity of the disease, and in several cases in which the parasites
were numerous the animals apparently enjoyed good health.
When the disease terminates in recovery, the trypanosomes
diminish in number, while the red corpuscles increase, and finally
the parasites disappear altogether from the blood.
Gall-sickness is often associated with other diseases, and this
complicates the study of it. Thus, piroplasms are often found, and
spirochastes are sometimes found in the blood of animals infected
with T. theileri, so that it is impossible to say exactly what part the
trypanosome plays in the production of the symptoms noted.
[As has already been stated, the cases of T. theileri infection seen
by Holmes, Lingard, Luhs, and Nabarro were all complicated by
some other infection or occurred in debilitated animals. Holmes'
cases were all more or less debilitated, or had been inoculated with
rinderpest serum. Lingard's cases were complicated with surra,
with filariasis in one case, and with anthrax in another case. Luhs'
six animals were all sick with cattle-plague, and Nabarro's case had
another trypanosome infection, probably with T. dimorphon, to which
the animal succumbed.]
Among forty cases which can be looked upon as simple infections
by T. theileri there were five deaths, giving a mortality of 12^ per
cent. (Theiler).
' Theiler has counted as many as thirty trypanosomes in one field of the micro-
scope {Zeiss. Obj., No. 6) ; an average of five is by no means uncommon. In
other cases only one parasite may be found in the whole film of blood examined.
GALZIEKTE (GALL-SICKNESS)
347
Section 4.— Patholog-ieal Anatomy.
Anaemia and hypertrophy of the spleen are the most noticeable
changes seen post-mortem in cattle that have died of gall-sickness.
The blood is watery and all the organs and tissues are pale in
colour, but sometimes they have an icteric tint. The subcutaneous
tissue of the abdominal walls is often the seat of a serous infiltration,
and the pericardium contains a variable quantity of fluid. The heart
is flabby and shows subpericardial petechia. There is hypostatic
cedema of the lungs. The spleen is enlarged and softened, and the
mesenteric glands are often swollen.
Section 5. — The Pathog-enic Ag-ent.
T. theileri is easily distinguished from the other mammalian
trypanosomes by its size. The largest forms measure 6o fj. to yo fi
Fig. 45. — Trypanosoma theileri and Trypanosoma transvaaliense.
I [and 2. T. theileri; Fig. 2 shows a trypanosome undergoing division. 3-5. T. trans-
vaaliense; Fig. 4 shows a trypanosome in the last stage of division ; Fig. 5, a small
form undergoing division. (Magnified about 1,700 diameters.)
in length, by 4 /x to 5 yx in breadth. The smallest forms are 25 /j, to
30 n long, by 2 /i or 3 /i wide.
In fresh blood the movements of the parasite are so rapid that
one cannot easily make out its shape, but on keeping the prepara-
tions for several hours, or even for two or three days, the motility
diminishes, and it is then possible to distinguish the chief morpho-
logical characters of the trypanosome. This trypanosome moves as
a rule with the flagellum foremost, but sometimes the non-flagellated
end leads the way. There is a long flagellum and an undulating
membrane. The posterior end of the body is usually pointed.
On fixing and staining in the ordinary way, one can distinguish
(Fig. 45, 7) an oval nucleus («) situated about the middle of the
body, and a round darkly-stained centrosome (c), situated a con-
348 TRYPANOSOMES AND THE TRYPANOSOMIASES
siderable distance from the posterior extremity. The free iiagellum
is about one quarter of the whole length of the parasite. The
flagellum itself starts from the centrosome, and runs along the
undulating membrane (ot), which is fairly wide and shows several
folds. The protoplasm stains deeply and contains a large number
of chromatic granules.
Multiplication takes place by simple fission. Fig. 45, 2 shows
a trypanosome undergoing division ; the centrosome has divided, and
the root of the flagellum has also begun to divide.
[The trypanosome seen by Liihe in the blood of Transcaucasian cattle
appears to differ in some respects from the foregoing. The centrosome is
not round, but elongated transversely to the long axis of the body ; some-
times it is dumb-bell-shaped — 'like a diplosome ' — which may possibly
indicate commencing division. The nucleus is like that of other trypano-
somes ; the chromatin is grouped in a number of rounded bodies, one
of which — the karyosome — is sometimes more deeply stained than the
rest. The relative positions of the nucleus and centrosome may differ.
This has led Laveran and Mesnil to distinguish two species of this
trypanosome — T. theileri and T. transvaaliense — but Liihe thinks they are
varieties of the same trypanosome, and Theiler and Luhs are of the same
opinion. The form Liihe calls the typical form has a rounded nucleus
situated about the middle of the body, a centrosome about midway between
the nucleus and the posterior end, and few chromatic granules. The
other form — T. transvaaliense of Laveran and Mesnil — has an oval nucleus,
which is situated further back than in the typical form, and which may
even be posterior to the centrosome. This form has many chromatic
granules. Liihe found fewer individuals of the latter variety in his blood-
films. He also saw transitional forms, and therefore concludes that these
two trypanosomes are the same species.]
[In addition to the typical and other forms just described, Liihe
figures another (? J ) form of the parasite resembling those he and
other observers describe in T. hnicei, T. eguimivi, and some of the other
mammalian trypanosomes. This female (?) form is very large, and is
broader than the ordinary form. It has a pale-staining alveolar proto-
plasm ; the nucleus consists of an oval ring of chromatic bodies, and lies
across the long axis of the body of the parasite.]
[Both Liihe and Luhs describe myonemes, or a sort of fibrillar
envelope, like Prowazek found in T. lewisi.]
[Luhs observed that young forms resuUing from longitudinal division
always had the centrosome situated close to the nucleus, as in T. trans-
vaaliense.. Both he and Liihe regard T. transvaaliense as a developmental
stage of T. theileri.'}
T. theileri can live for seven days in defibrinated blood at the
room temperature or in the ice-chest, but not so long in the incu-
bator. In defibrinated blood diluted with horse serum or with
physiological saline the trypanosome can live as long as in undiluted
blood ; but the addition of water or of glycerine and water rapidly
kills the parasites. Exposing them to a temperature of 50° C. kills
them in less than twenty-four hours.
[Luhs found the trypanosome sluggishly motile after being kept
on ice for nine days, and on warming the preparation the motility
GALZIEKTE {GALL-SICKNESS) 349
increased. Kept at 20° C, the trypanosomes lost their motility in
six days, and at 38° C. in three days.]
Involution forms are often seen in blood-films. The protoplasm
stains badly, and the outline of the parasite is indistinct. The
centrosome and flagellum are the most resistant parts of the trypano-
some, and are often met with amongst the red corpuscles, the rest
of the parasite having disappeared.
Agglutination has been seen by Theiler under certain conditions.
Occasionally two parasites adhere by their posterior ends. When
defibrinated blood is allowed to stand, the trypanosomes come to the
surface and adhere together in the form of rosettes. Agglutination
is well marked on adding to the blood the serum of a calf which has
been inoculated on several occasions with T. theileri. In one case in
which the trypanosomes were very numerous, agglutination was
observed in blood examined fresh twenty-four hours after the animal
had received a big dose of immunizing serum. Before this injection
the blood had been examined, but no agglutination had been observed.
[Luhs also observed agglomeration of T. theileri when the
organism was under unfavourable conditions. He found that the
addition of salt solution to the blood did not prevent agglomeration.]
In films of blood from a bovine sent to us by Theiler from the
Transvaal one of us has seen and described under the name of
T. transvaaliense a trypanosome which morphologically appears quite
distinct from T. theileri.
T. transvaaliense varies considerably in size. In one and the
same film are seen small forms measuring on an average 18 /i in
length, including the flagellum ; large forms 40 u and even 50 /u,
long, by 6 /x in width ; and intermediate forms, which are the most
numerous, 30 fi long, by about 4 /x to 5 /^ wide. The posterior
extremity is as a rule very pointed.
The nucleus, which is oval in shape, is situated about the middle
of the body. The relation of the centrosome to the nucleus is
characteristic. In all the trypanosomes described hitherto the
centrosome has been situated far from the nucleus, and usually a
short distance from the posterior extremity of the body. That,
indeed, is an objection which has been raised to the interpretation
we have given of this chromatic corpuscule of trypanosomes in which
the flagellum takes origin.
In T. transvaaliense the centrosome, which is relatively large, and
therefore easily seen, is always situated near the nucleus, and often
adjoining it, as in Fig. 45, 3. It is usually elongated in form, and
stains more deeply than the nucleus by our method of staining.
On account of the approximation of the centrosome to the
nucleus, the undulating membrane is much less developed in
T. transvaaliense than in the other trypanosomes. The protoplasm
is finely granular, and stains less deeply than that of T. theileri.
T. transvaaliense multiplies by fission, like T. theileri, but the
350 TRYPANOSOMES AND THE TRYPANOSOMIASES
division forms are more varied than in the latter species. Fig. 45, ^
shows a parasite of medium size in the last stage of fission, and one
can distinguish two nuclei, two centrosomes, two flagella, and two
undulating membranes ; the protoplasm has also begun to divide.
Fig. 5 shows a small parasite undergoing fission, the centrosome
and adjacent part of the flagellum having already divided. In the
process of fission the flagellum divides throughout its whole length.
Some films were made with blood which had been kept for twenty-
four hours, and many of the trypanosomes were agglutinated into
more or less well-formed rosettes. Agglutination occurs by the
posterior extremities, as with T. lewisi and T. brucei. The proto-
plasm of these agglutinated trypanosomes was already showing
signs of degeneration, and contained large chromatic granules.
The coloured plate at the end of the book shows a T. theileri
(Fig. 8) and a T. transvaaliense (Fig. 9).
From Theiler's researches it would appear that T. transvaaliense
is not a distinct species, but a variety of T. theileri, for on injecting
blood containing T. transvaaliense into cattle Theiler succeeded in
producing ordinary gall-sickness.
[We have already seen that on morphological and developmental
grounds Liihe and Luhs also regard these two trypanosomes as
varieties of one species.]
Section 6. — Mode of Propag-ation.
Gall-sickness is easily inoculable from one bovine into another
by the subcutaneous or intravenous injection of virulent blood. The
Fig. 46. — HippoBoscA rufipes. x 2 (about). (After Theiler.)
The small, round, white area, mesially situated at the posterior part of the thorax, is in
nature red in colour, and on either side there is a small grey area.
incubation period is from four to six days when a large dose of blood
containing many trypanosomes is injected, but may be as long as
eighteen or twenty days if the blood injected contains very few
parasites. Blood may still be virulent, even though it show no
parasites on microscopical examination. According to Theiler, the
inoculations of defibrinated blood for cattle-plague in the Transvaal
have contributed to the spread of gall-sickness.
By analogy with what happens in nagana, one would suppose
GALZIEKTE (GALL-SICKNESS) 35i
that gall-sickness was propagated by biting flies. Theiler's investiga-
tions show that the greatest suspicion falls upon Hippobosca riifipes,
which is very common in South Africa.
Several specimens of Hippobosca, after having been starved, were
placed upon an animal infected with gall-sickness, and immediately
afterwards upon a healthy animal. In two cases out of four the
healthy animals so experimented upon became infected. An hour
after feeding the blood in the stomach of the flies shows trypano-
somes as active as in fresh blood.
Theiler has sent us some specimens of Hippobosca from the
Transvaal, which have been identified by Dr. Speiser of Bischofs-
burg. According to Speiser, these flies belong to two species :
H. rufipes, v. Olfers, and H. maculata, Leach. The latter is very
rare in South Africa, where it appears to have been introduced at
the time of the Boer War with cavalry horses coming from India.^
Section 7. — Treatment. Prophylaxis.
At present we know of no treatment for gall-sickness. Cattle
which survive an attack are immune. We have seen that the native
cattle in the Transvaal are less susceptible to the disease than im-
ported cattle ; therefore foreign animals should not be introduced
into areas where the disease is prevalent.
Sick animals should be isolated. Killing them would be the
most radical and efficacious measure, but it is difficult to enforce
this in the case of a disease the gravity of which is not yet known
with certainty, and which, moreover, often ends in recovery.
Healthy cattle should be protected as much as possible from
biting flies by the methods suggested in previous chapters.
The inoculations for cattle-plague appear to have spread gall-
sickness in the Transvaal ; therefore, if such inoculations should still
be necessary, it should be ascertained beforehand that the animals
from which the blood is taken are free from gall-sickness.
^ Laveran, ' Concerning Two Species of Hippobosca from the Transvaal,' Soc.
de Biol., February 21, 1903.
CHAPTER XII
HUMAN TRYPANOSOMIASIS, including SLEEPING
SICKNESS
Pathogenic Agent : Trypanosoma gambiense, Dutton, 1902.
Section 1. — Historical.
At the beginning of last century the English observer Winter-
bottom^ recorded the occurrence among the negroes on the West
Coast of Africa of a curious disease characterized particularly by a
tendency to sleep. Since that time the disease has been described
by a large number of observers, and under the name of sleeping sick-
ness it has found a place in all treatises upon tropical diseases.
In 1840 Clarke^ of Sierra Leone gave a short account of the
disease. From 1861 to igoo French naval surgeons published a
series of very interesting papers upon the clinical and pathologico-
anatomical study of sleeping sickness. The most important of these
are by Dangaix,^ Nicolas,* Griffon du Bellay,^ Chassaniol," San-
telli,' Guerin,8 Le Roy de Mericourt,^ Correi" Mah^," Nielly,!^ and
Le Dantec.^^
Guerin's excellent thesis deserves special mention. He studied
the disease in Martinique in negroes coming from the West Coast
of Africa. In the course of a dozen years he observed as many as
148 cases.
Hirsch has given a good description of the disease, and in his
excellent vi^ork on the ' Historical and Geographical Pathology of
^ Winterbottom, 'An Account of Native Africans in the Neighbourhood of
Sierra Leone,' 1803.
2 Clarke, London Med. Gaz., September, 1840; Edinburgh Monthly Journ.
Med. Science, 1842, p. 320.
^ Dangaix, Moniteur des Hop., 1861, p. 100.
"* Nicnlas, Ga2. hebdom., 1861, p. 670.
•^ Griffon du Bellay, Arch, de niM., 1864, i" sem., p. 73.
^ Chassaniol, Arch, de mid. nav., 1865.
7 Santelli, ibid., 1868.
8 Guerin. Thfese, Paris, 1869.
^ Le Roy de Mdricourt, article ' Sleeping Sickness ' in the Diet, encycl. des so,
mM., 1871.
^" Corre, Arch, de nied. nav., 1877.
" Mah^, ' Syllabus for the Study of Tropical Diseases,' 1888.
12 Nielly, ' Elem. de pathol. exotique,' 1881, p. 503.
'■^ Le Dantec, ' Pathol, exotique,' igoo, p. 759.
352
HUMAN TRYPANOSOMIASIS 353
Diseases ' gives a bibliography of all the papers dealing with sleep-
ing sickness.^
The conquests of bacteriology were destined to receive, and have
received, their set-back in the history of sleeping sickness. A. de
' Figueiredo,^ Cagigal and Lepierre,^ Marchoux,* Bettencourt,*
Broden,^ and Castellani,'' have attributed to different Bacteria
(bacilli, pneumococci, streptococci, etc.) the role of pathogenic agent
in sleeping sickness. The variety of the microbes isolated by these
observers tends to prove that the causes of secondary infection, so
common in this disease, have been looked upon as the actual causal
agent of the disease.
Several observers have attributed the disease to bad or insufficient
feeding. Ziemann has held this opinion, and, according to him, the
disease is due not to an infection, but to an intestinal intoxication.
This intoxication is said to be produced by the root of the manioc
eaten raw or only slightly cooked, as is often done by natives.^ A large
number of facts tell against this opinion. In Casamance, where little
or no manioc is eaten, sleeping sickness is very prevalent, whilst in
Dahomey, where this root enters largely into the native dietary, the
disease occurs but rarely.^ It has been shown, moreover, that the
disease may occur in well-nourished people, who for several years
have left those districts where manioc is eaten. The incrimination
of certain mud fish in Casamance is also unjustified.
In igoo Manson gave a very full account of two patients from
the Congo who died in Charing Cross Hospital, and the pathological
anatomy of these two cases was very carefully worked out by Mott.^"
Manson has attributed sleeping sickness to an infection by a
filaria which he has described under the name of Filaria perstans.
It is true this filaria is often met with in the blood of negroes suffer-
ing from sleeping sickness, but it is also found in districts where the
disease does not occur." Low has recorded the existence of F. perstans
in British Guiana, where sleeping sickness has never occurred. We
1 Hirsch, ' Handbuch der hist, geogr. Patholog.,' 1862; second edition, 1880-
1882. [Translation published by New Sydenham Society, see vol. iii., pp. 595-
602.]
2 Figueiredo, ' Inaugural Dissertation,' Lisbon, 1891.
2 Cagigal and Lepierre, MMecine moderne, January 26, 1898.
* Marchoux, Ann. cFhyg. et de med. colon., 1899, p. 13.
^ Bettencourt, 'Doenga do Somno,' Lisbon, 1901.
^ Kuborn's Report upon Broden's work, Acad, de med. de Belgique, October 26,
1901.
' Castellani, Brit. Med. Journ., March 14, 1903.
^ Ziemann, Centralb.f. Bakter., I, Orig., v. 32, 1903, p. 413.
^ Kermorgant, Acad, de mid., December 29, 1903.
"> Manson, 'Tropical Diseases,' third edition, 1903, p. 335. [Also 'African
Lethargy, or the Sleeping Sickness,' P. Manson and F. W. Mott, Trans. Path
Soc, V. 51, 1900.J
" Low, Brit. Med. Journ., March 28, 1903. Christy, Annual Meeting of
British Medical Association at Swansea, July, 1903 ; Journ. Trap. Med., 1903.
Low, Royal Society Reports oj the Sleepitig Sickness Commission, November, 1903.
Christy, ibid., November, 1903.
23
354 TRYPANOSOMES AND THE TRYPANOSOMIASES
may add that in many cases of sleeping sickness the filaria cannot be
found. This hypothesis of Manson's must, therefore, be given up.^
The researches of Button and Todd, of Castellani, and of Bruce,
Nabarro, and Greig upon human trypanosomiasis mark the latest
phase in the elucidation of the setiology of sleeping sickness. It
would seem that the careful investigations of these observers have at
last discovered the true cause of this disease.
On May lo, 1901, Forde received under his care at the hospital
in Bathurst (Gambia) a European, aged forty-two, the captain of a
steamer on the River Gambia. This man, who had navigated the
river for six years, had suffered from several attacks of fever which
were looked upon as malarial. The examination of his blood
revealed the presence not of the malarial parasite, but of small worm-
like bodies, concerning the nature of which Forde was undecided.
On December 18, 1901, Button, in conjunction with Forde,
examined this patient, whose condition had become more serious,
and recognised that these worm-like bodies seen by Forde were
trypanosomes. Button has given an excellent description of this
parasite, which he has called Trypanosoma gambiense.^
In IQ02 Button and Todd came across further cases of human
trypanosomiasis. Of 1,000 persons examined in Gambia,^ six natives
and one quadroon showed trypanosomes in their blood. The cases
observed amongst the natives were as follows : A woman of thirty-
five, a boy of nine, a girl of sixteen, a boy of twelve, a man of thirty-
five, and another of twenty-two. The first three belonged to the
same village — Lamin.
Manson has recorded two cases of trypanosomiasis in Europeans
contracted on the Congo.* In one of these cases the trypanosomes
1 [For a full account of the earlier hypotheses as to the aetiology of sleeping
sickness, see Centralb. f. Bakter., I, Orig., v. 35, 1903, p, 45, ' Ueber die ^tiologie
der Schlafkrankheit,' by Betteniourt, Kopke, de Rezende, and Mendes ; also p. 62
for a paper by Castellani.]
^ Forde, Journ. Trap. Med., September i, 1902 ; Dutton, ibid., December i,
1902 ; Dutton, Thompson Yates Lab. Report, 1902, v. 4, part ii., p. 455. The
patient who formed the subject of these observations by Dutton and Forde died in
England on January i, 1903. See a note by Annett, Brit. Med. Journ., February 7,
1903.
Previously, Nepveu had recorded the existence of trypanosomes in the blood of
several patients coming from Algeria, but his descriptions and figures are so
lacking in precision that there is considerable doubt about the correctness of this
diagnosis. Although in recent years the blood of a very large number of patients
in Algeria has been examined, trypanosomes have never been seen again in them
(Nepveu, Soc. Biol., 1891, Memoirs, p. 49 ; and Soc. Biol., December 24, 1898). —
In 1894 Barron recorded the case of a woman of thirty-nine with a uterine fibroid,
in whose blood a large number of flagellated Protozoa were found. The retro-
spective diagnosis of trypanosomes may be made in this case. The patient had
not lived in Africa, so far as can be judged from the short note by Barron {Trans,
of the Liverpool Med. Institution, December 6, 1894). In 1898 Brault brought
forward the ^hypothesis that possibly the trypanosome was the causal agent in
sleeping sickness (Janus, July to August, 1898, p. 41).
^ Dutton and Todd, First Report of the Trypanosomiasis Expedition to Sene-
gambia, 1902, Liverpool, 1903.
■* Manson, /o7ir«. Trop.Med., November I, 1902, and March 16, 1903. Manson
and Daniels, Brit. Med. Journ., May 30, 1903.
HUMAN TRYPANOSOMIASIS 355
were discovered by Broden, Director of the Bacteriological Labora-
tory at Leopoldville, Congo Free State.^
Brumpt has recorded the existence of T. gamhiense at Boumba,
situated at the junction of the Ruby and the Congo, in a ship's
steward, who suffered for several months from irregular fever, which
did not respond to quinine.^ Lastly, Baker has seen three cases of
trypanosomiasis in Entebbe, Uganda. The parasites were numerous
in one case, scanty in the other two.^
The relation between human trypanosomiasis and sleeping sick-
ness was not suspected * when Castellani, examining "the cerebro-
spinal fluid of negroes in Uganda suffering from sleeping sickness,
discovered trypanosomes which were at first thought to be a different
species, and were described under the names of T. ugandense (Castel-
lani) and T. castellanii (Kruse).^
This important discovery was immediately confirmed by Bruce
and Nabarro, who found trypanosomes in each of thirty-eight cases
in the cerebro-spinal fluid obtained by lumbar puncture from sleeping
sickness patients in Uganda, and twelve out of thirteen times in
the blood. The cerebro-spinal fluid of ' control ' individuals, not
suffering from sleeping sickness, never showed trypanosomes.
We shall frequently have occasion throughout this chapter to
quote from the interesting reports by Bruce, Nabarro, and Greig,''
upon sleeping sickness in Uganda.
In the Congo State, Brumpt found trypanosomes twelve out of
fifteen times in patients suffering from sleeping sickness.'^
The Portuguese Commission for the study of sleeping sickness
re-examined the blood-films of twelve of their patients which had
been used during the course of their investigations, and found
trypanosomes in four of them. ^
' Broden, Bull, de la Soc. cV etudes coloniales, Brussels, 1903, No. 4.
2 Brumpt, Acad, de mid., March 17, 1903 ; Bulletin., v. 49, p. 372.
'' Baker, Brit. Med. Joiirn., May 30, 1903, p. 1254.
■* [Before the publication of Castellani's discovery of trypanosomes in the
cerebro-spinal fluid of sleeping sickness patients, Maxwell-Adams had suggested
the relationship between trypanosomiasis and sleeping sickness on the ground that
certain features (pufliness of the face and lower eyelids, irritability and apathy,
and characteristic alteration in the voice) were common to both diseases. He also
made the rather improbable suggestion that the disease is conveyed by the bite of
rats, or by a rat-flea (see Brit. Med. Journ., March 28, 1903, and April 16, 1904
p. 889).]
" Castellani, letter dated Entebbe, Uganda, April 5, 1903, addressed to the
Royal Society, Brit. Med. Journ., May 23, 1903, and June 20, 1903; 7d%o /ourn.
Trap. Med., June i, 1903. Kruse, ' Sitzungsbericht der niederrhein. Gesell. f.
natur. Heilk,' 1903. Castellani, Proc. Roy. Soc, v. 71, 1903, p. 501, and Heporis
of the Sleeping Sickness Commission, No i, August, 1903.
'• Royal Society, Reports of the S/i-tping Sickness Commission : No. i, by Bruce
and Nabarro, Progress Report on Steeping Sickness in Uganda, London, August
1903 : No. 4, Further Report on Sleeping Sickness in Uganda, by Bruce, Nabarro'
and Greig, November, 1903. R^sumdm Brit. Med. Journ., November 21, 1903.
^ Brumpt, Congris d" Hygiene de Bruxelles, 1903.
8 A medicina contemporanea, June 28, 1903 ; also Report oji Sleeping Sickness
presented to the Minister of Marine and of the Colonies by the Commission
presided over by Bettencourt, Lisbon, 1903.
23—2
356 TRYPANOSOMES AND THE TRYPANOSOMIASES
In the Congo Free State, Dutton, Todd and Christy,^ and
Broden^ also found trypanosomes in the cerebro-spinal fluid of a
large number of negroes suffering from sleeping sickness.
[Subsequent investigations in all parts of Africa in which
sleeping sickness occurs have confirmed the original observations of
Castellani, Bruce, and Nabarro. If carefully looked for, trypano-
somes are practically always found in the cerebro-spinal fluid, blood,
and gland-juice of sleeping sickness patients. Moreover, clinical
and experimental evidence is being gradually accumulated, which
goes to prove that a trypanosome is the cause, and probably the sole
cause, of sleeping sickness. Patients who had acquired trypano-
somiasis in Africa have died of sleeping sickness as long as three
years after returning to Europe, and a patient of Thiroux's with
sleeping sickness had left the endemic area eight years. ^ In a
monkey experimentally infected with T. gambiense, in which the in-
fection ran a chronic course (like trypanosomiasis ending as sleeping
sickness does in the human subject), the macroscopic and microscopic
lesions in the central nervous system typical of human sleeping
sickness have been observed.* Lastly, we have seen that in uncom-
plicated chronic dourine— another trypanosome infection — micro-
scopical changes very similiar to those occurring in sleeping sickness
have been described by Mott.]
It still remained to be seen if T. gambiense and T. ugandense were
different species, or if the parasite found in sleeping sickness patients
was really the T. gambiense.
Bruce, Nabarro, and Greig showed that twenty -three out of
eighty natives from parts of Uganda where sleeping sickness is
endemic had trypanosomiasis in their blood,^ whilst in 117 natives
from uninfected areas the blood examination was negative in every case.
The same observers have shown that, contrary to the statements
of Castellani, there is no appreciable morphological difference
between T. gambiense and T. ugandense.
Dutton, Todd, and Christy, in their ' Report upon Trypano-
somiasis on the Congo,'^ arrived at the same conclusion. They state
that the parasites seen in the blood of individuals, whether showing
signs of sleeping sickness or not, are identical, and there is no reason
to suppose that the trypanosome observed on the Congo differs from
T. gambiense.
The pathogenic action of the two trypanosomes upon different
species of mammals is the same. Thomas and Linton have made
a comparative study of the human trypanosomes derived from
1 Brit. Med. Jnurn., January 23, 1904, p. 186.
^ Broden, Bull, de la Soc. d etudes colon, Brussels, February, 1904.
3 [Thiroux, C. R. Soc. Biol., v. 60, 1906, p. 778.]
■* [Harvey, R.A.M.C. Journ., v. 4, 1905, p. 621.]
^ [For the after-history of these twenty-three infected individuals, see later
(Section 10).]
^ Brit. Med. Journ., January 23, 1904; [also Thompson Yates and Johnston
Lab. Reports, v. 6, part i., 1905, pp. 1-45.]
HUMAN TRYPANOSOMIASIS 357
different sources : (i) Trypanosomas brought from Gambia by
Button and Todd ; (2) trypanosome of Bruce and Nabarro from
Uganda ; and (3) trypanosomes of Button, Todd, and Christy from
the Congo (from the cerebro-spinal fluid of sleeping sickness patients,
and from the blood of individuals showing no sign of this disease).
Thomas and Linton inoculated the trypanosomes from these various
sources into a large number of animals, and they found that the
pathogenicity was almost the same in all cases.^ Our researches
upon T. gambiense and T. ugandense have yielded the same results.^
[Laveran^ has since studied the pathogenic action upon animals
(guinea-pigs, rats, and mice) of three different strains of the human
trypanosome : (i) The Gambian trypanosome from a patient in the
first stage of trypanosomiasis ; (2) the Uganda parasite from a case
of sleeping sickiless ; and (3) a trypanosome from the blood of a
missionary in Paris, who contracted the disease in the Ubangi
district (French Congo). The virulence of all three strains was
about the same.]
[Plimmer'' concludes, from certain experiments he has made upon rats,
that T. gambiense and T. ugandense are ' quite distinct and separate.' Rats
inoculated with the ' Gambia fever ' trypanosome all showed trypanosomes
in blood-films, and died on an average two months and twelve days after
inoculation. Paralysis and nervous symptoms were absent, but shortly
before death the animals became heavy and apathetic. Post-mortem, the
spleen was very enlarged and congested, the lymphatic glands were
swollen, and the liver was congested and showed cloudy swelling. The
cerebral capillaries contained many organisms. On the other hand, rats
inoculated with the sleeping sickness trypanosome never showed the
parasites in their blood, even on centrifuging post-mortem. All three
animals inoculated with this trypanosome became paralyzed two to four
weeks before death, and the total duration of the infection was six to nine
months. Post-mortem, the spleen was not enlarged in any of the rats,
nor could any lesions be found in the other organs. Trypanosomes were
found only in the mashed spinal cord, and extracts of the mashed cord
produced paraplegia on injection into other rats, but no trypanosomes
could be found in these animals.]
[The fact that cases of ' trypanosome fever ' frequently appear to
terminate in sleeping sickness, Plimmer thinks may be explained by a
double infection with these two trypanosomes.^]
[Thomas and Breinl,^ who experimented on a large number of rats
with several strains of the human trypanosome, including the same
two strains used by Plimmer, obtained results confirming those of
Thomas and Linton and of Laveran,and opposed to those of Plimmer.]
1 Thomas and Linton, Lancet, May 14, 1904, pp. 1337-1340.
2 Owing to the kindness of Dutton, Todd, .\nnett, and Bruce, I have been able
to study the trypanosomes of Gambia and Uganda at the Pasteur Institute. I
take this opportunity of thanking them all for their kindness. — A. Laveran.
^ [Laveran, C. R. Acad. Sciences, v. 142, 1906, p. 1065.]
* [Plimrner, Proc. Roy. Sac, v. 74, 1905, p. 388]
^ [In a later paper {Proc. Roy. Soc. Ser. B., v. 79, 1907, p. 95) Plimmer gives
up the idea that the two strains of human trypanosome are distinct species.]
^ [Thomas and Breinl, Thompson Yates and Johnston Lab. Reports, v. 6,
part ii., 1905, pp. 93, 94.]
358 TRYPANOSOMES AND THE TRYPANOSOMIASES
[Gray and Tullochi have also studied the effects of different
strains of the trypanosome upon white rats. Their results do not
confirm those of Plimmer, for they found that the same strain of
trypanosome produced the two different clinical types of the disease
mentioned by Plimmer.]
[It is now almost, if not quite, universally believed that T. gambiense
and T. ugandense are the same species.]
The objection might still have been raised that the symptoms
produced by T. gambiense were not those of sleeping sickness. The
case recorded by Manson shows that symptoms of sleeping sickness
may supervene in a patient who at first has exhibited only the
symptoms due to T. gambiense. It was one of those cases originally
recorded as an instance of typical T. gambiense infection^ (p. 354).
The patient, who died on November 26, 1903, presented character-
istic symptoms of sleeping sickness during the last few months of
her illness, and the lesions found at the autopsy were like those met
with in sleeping sickness.^ This observation is of great importance.
It is a very strong argument in favour of the identity of T. gambiense
and T. ugandense, and, moreover, it shows that, contrary to what
was formerly beheved, Europeans are not immune against sleeping
sickness.
Finally, it appears to follow from observations of Nabarro,* as
well as from our own,^ that monkeys which have acquired immunity
against T. gambiense are also immune against T. ugandense, and vice
versa.
[Subsequent investigations have shown, however, that this
acquired immunity is apparent rather than real. Trypanosomes
may disappear from the blood of monkeys and remain absent for
more than a year, as in the case recorded by Harvey, reappearing
shortly before death. Laveran^ and Thomas and Breinl'' have
recently expressed the opinion that no immunity is attainable with
the trypanosome of sleeping sickness.]
According to the rules of priority in nomenclature, the name
T. ugandense (Castellani) should disappear, and the older name
T. gambiense (Dutton) should be retained.
Further, the name sleeping sickness, which aptly describes the
ultimate symptoms produced by T. gambiense,^ is not a good one to
1 [Gray and Tulloch, Sleeping Sickness Reports, No. 8, 1907, pp. 53-63.]
^ Manson, Brii. Med- Journ., May 30, 1903, and December 5, 1903, p. 1461.
5 [Low and Mott, Brit. Med. Journ., April yi, 1904, p. 1000.]
* Nabarro, ' Epidemiological Society,' Lancet, January 23, 1904.
° Laveran, C. R. Acad. Sciences, April 5, 1904.
'' [Laveran, Report presented to the Fifteenth Itrternational Medical Congress,
Lisbon, 1906. Abstract in Brit. Med. Journ., ]mxi& 2, 1906, p. 1287.]
'' [Thomas and Breinl, op. cit., p. 24.]
^ [Bruce and Nabarro found that many of their cases of sleeping sickness in
Uganda did not really sleep excessively. Dutton, Todd, and Christy also draw
attention to the minor importance of sleep in their cases of Congo trypanosomiasis.
Corre had previously made the same observation, for in 1877 he wrote : ' Somno-
lence, exceptionally pushed as far as coma, rarely continues, and is not absolutely
constant. All the patients with sleeping sickness do not sleep. Many remain
HUMAN TRYPANOSOMIASIS 359
give to the early stage of the infection, which is characterized solely
by the presence of a few trypanosomes in the blood and by irregular
rises of temperature. The name Human Trypanosomiasis is there-
fore to be preferred to the older names Sleeping Sickness and Negro
Lethargy.
Section 2. — Geographical Distribution.
Trypanosomiasis is endemic only in certain parts of Equatorial
Africa. It has sometimes been seen in the Antilles, but only in
negroes coming from the West Coast of Africa. That explains how
Guerin was able to study the disease in Martinique.
The chief foci of the disease are found along the coast of West
Africa, extending from Senegal to St. Paul de Loanda (see map).
[Wellman'- has recently described cases of human trypanosomiasis
in South Angola — considerably to the south of St. Paul de Loanda
— and the natives state that sleeping sickness is advancing south
through the province.]
In Senegambia the disease is common in Casamance and in
Sine and Saloum. Cases have been recorded along the banks
of the River Senegal in the neighbourhood of Bakel, Kayes, and
Bafoulabe.^
In Gambia trypanosomiasis is by no means rare ; and, as we
have seen above, it was in Gambia that trypanosomes were first
discovered in human blood. According to the researches of Button
and Todd, only a small proportion of the natives of Gambia are
infected ; but it is probable that, by using other methods of diagnosis,
a larger proportion of infected individuals would be found. Cases of
true sleeping sickness are met with, as well as the earlier stages of
trypanosome infection which were studied by Button and Todd.
Trypanosomiasis is prevalent from the mouth of the Gambia to
a distance of 250 miles up the river. In French territory, at Maka,
about thirty miles from the banks of the River Gambia, Button and
Todd examined a hundred natives, but did not find trypanosomes in
any of them.
Amongst the most infected areas may be mentioned : Upper
Guinea, the hinterland of Sierra Leone, of Liberia, and of the Ivory
Coast, Lobi, or the country of the Bobos, and Yatenga.
On several occasions the disease has become epidemic at Roba,
in Yatenga. In 1850 there were more than 180 victims in this
district. From 1886 to 1889, in four other villages in the same
district, 300 natives died of sleeping sickness.
Secondary foci have been recorded at several points along the
lying down, the eyelids closed, half closed, or quite open, but profoundly indifferent
to all going on around them ' (quoted from Hirsch's ' Geographical Pathology ').]
1 [F. C. WeUmsLTi, /ourn. Hyg., v. 6, 1906, p. 237.]
2 Kermorgant, ' Distribution of Sleeping Sickness in the French West African
Colonies,' Acad, de mM., December 29, 1903.
36o TRYPANOSOMES AND THE TRYPANOSOMIASES
Upper Niger, [but Laveran^ has recently stated that human trypano-
somiasis is rare in this district] .
[Renner^ has described sporadic or imported cases of the disease
in Sierra Leone ; but later investigations by Grattan and Cochrane*
show that trypanosomiasis is much commoner in Sierra Leone than
is usually supposed.]
[Between July and December, 1905, Grattan-* saw eighteen cases— all
confirmed by the microscope— and states that probably several more were
Laveran, C. R. Acad. Sciences, v. 143, July 9, igo6, p. 94.] J
Renner, /t72/r«. Trop. Med., v. 7, November 15, 1904.]
Grattan and Cochrane, R.A.M.C. Journ., v. 6, 1906, p. 524.]
Grattan, R.A.M.C. Journ., v. 7, 1906, p. 485.]
HUMAN TRYPANOSOMIASIS 361
not diagnosed. Gland palpation and puncture were used in the diagnosis,
and found to be much easier than the examination of the blood, either in
films or by centrifuging. The disease has been contracted in Sierra
Leone by natives who have never been out of the colony or protectorate,
so that some of the fly belts are now infected.]
[Gl. palpalis is common in Sierra Leone ; Grattan caught specimens at
Materri, near Port Lokkoh, Melanki, Robarri, Ronietta, Yonnibana,
Moyamba, Makali, Medina, and Magbele. Some of the flies caught at
Warima and Robarri were Gl. fusca. Trypanosomiasis was found to
occur at Freetown, Regent, Yonnibana, Kissi Wellington, Port Lokkoh,
Waterloo, Tikonko, and Bonthe, at all of which (except the last three)
Gl. palpalis is present]
[An imported case of sleeping sickness in a native of Lagos has
been described by Taylor and Currie."^ According to G. Martin,^
sleeping sickness is probably present throughout French Guinea.
Gl. palpalis is also very widely distributed, but only a small propor-
tion of the natives are affected by trypanosomiasis.]
[Krueger^ has described several cases of sleeping sickness in Togo,
and states that the disease is endemic there, 115 deaths having
occurred from this disease in recent years. Gl. palpalis is also very
prevalent.]
According to Ziemann, sleeping sickness is also prevalent
along the coast at Monravia and Accra, and in several districts of
Cameroon, notably at Etun-beka-ha and at Etun-bekani.'^
[Gl. palpalis is found in several of the coast districts in Cameroon,
such as Victoria, Buea, Barombi, so that all the conditions for the
spread of sleeping sickness are present (Ziemann).]^
The islands of Princes, St. Thomas, and Fernando Po are also
infected.
In Portuguese Congo (Angola) the disease occurs principally in
the region of Quissama and along the banks of the River Coanza.^ In
the town of Dondo and its environs there were, in igoo, g8 deaths from
sleeping sickness amongst 2,000 negroes or half-castes. At Tombo,
near the mouth of the Coanza, practically the whole population has
been carried off by the disease. At Benguella the disease is less
prevalent than in Loanda, and still further south, particularly in the.
province of Mossamedes, it disappears entirely.
[Wellman'' states that the River Coanza seems to mark the south
limit of the zones of endemicity of sleeping sickness, but recently
' [Taylor and Currie, Brit. Med. Joiirn., February 4, 1905, p. 248.]
^ [G. Martin, Ann. Hyg. et Med. colotz., v. 9, 1906, p. 304 ; Les Trypano-
somiases de la Gziinee frangaise, Paris, 1906, chapter x.J
^ [Krueger, Arc/i. f. Schiffs in Tropen Hyg., v. 8, 1904, p. 479; abstract in
Bull. Inst. Past., v. 3, 1905, p. 47.]
^ Deutsche med. Wocheitsckr., April 2, 1903. For the distribution of human
trypanosomiasis in Togo, see K. Hintze, Deutsche med. Wochenschr., May 1,9 and
26, 1904, pp. 776, 812.
^ [Ziemann, Centralb.f. Bakter., I, Orig., v. 38, igoj, p. 307.]
^ Report of the Portuguese Commission, Lisbon, 1903.
^ [F. C. Wellman, ' Notes from Angola' in /o;(;'«. 7>-o/. Af^^., v. 8, pp. 319, 320,
and 327, 328 ; a\50 Joiirn. Hyg., v. 6, igo6, p. 237.]
362 TRYPANOSOMES AND THE TRYPANOSOMIASES
three cases of trypanosomiasis were seen by Wellman and Fay in
natives who had never left their district (South Angola). According
to native accounts, sleeping sickness is advancing south through this
province. To the north of the Coanza typical Gl. palpalis are found,
but to the south one finds a variety — Gl. palpalis wellmani, Austen.]
[Kopke'- has studied fifty-two cases of sleeping sickness from
various Portuguese West African colonies. He used gland puncture
in the diagnosis and found T. gambiense present in every case.
Lumbar puncture was performed in forty cases, and in every case —
even in the absence of nervous symptoms — trypanosomes were found
in the cerebro-spinal fluid.]
Sleeping sickness is endemic in French Congo and in the Congo
Free State, where for several years it has been extending rapidly and
causing great ravages. Sporadic cases are also met with at I'Ouelle,
Basako, Bangala, Leopoldville, and Boma. The disease is endemic
in the neighbourhood of the falls, especially at Banza Manteka. In
the training college at Berghe-Ste. -Marie, at the junction of the
Kasai and the Congo, cases of sleeping sickness have multiplied
rapidly in recent years. The mortality, which in 1896 was 13 per
cent, and in 1897 19 per cent., rose in the following years to 39 and
22 per cent, respectively, and in the first quarter of igoo to 73 per
cent. The majority of the children died of the disease. At the time
van Campenhout^ visited the colony eighty-two patients with sleeping
sickness came to see him, and there were many others who did not
come.
The whole population of the left bank of the Congo, from the
mouth of the Kasai to Bolobo, higher up the river, has fallen a prey
to the scourge which has decimated the villages of the Botanguis.
[Kermorgant,^ in a series of papers, gives details of the frequency
of sleeping sickness along the French banks of the Congo and of its
tributary the Ubangi, as far as Bangi, and in Loango. The disease
is rare at Libreville, and in the valleys of the Ogoue and Upper
Sanga.]
[In an interesting paper on ' A Means of Checking the Spread of
Sleeping Sickness,' Todd* shows that the enormous spread and great
increase of sleeping sickness in the Congo basin have been due in
great measure to the increase in travel following the opening up of
the country. Before Europeans entered the Congo basin (1884) the
1 [A, Kopke, ' Fifteenth International Congress of Medicine,' Lisbon, 1906 ;
also Arch, de Hyg. et Path, exot., v. i, 1905 ; abstract by Mesnil in Bull. hist.
Past., V. 4, 1906, p. 671.]
2 Van Campenhout and Dryepondt, Rapport sur les travaux du laboratoire
midicale de Leopoldville en 1899-1900, Brussels, 1901, and Paris International
Congress, 1900 (section on Colonial Medicine).
^ [Kermorgant, Ann. d'Hyg. et de Med. colon, 1903-1906; ibid., v. 9, 1906,
p. 126 ; abstract by Mesnil in Bull. Inst. Past., v. 4, 1906, p. 531.]
* [J . L. Todd , Transactions of the Epidemiological Society, 1 906 ; also Lancet,
July 7, 1906, pp. 6-9, with three maps; and Memoir 18 of the Liverpool School of
Tropical Medicine, 1906, pp. 23-38, with four maps.]
HUMAN TRYPANOSOMIASIS 363
disease seems to have been confined to the region of the Lower Congo
and to the banks of the main river as high up as Bumba. With the
advent of white men new steamer and caravan routes were opened
up, with the result that the infected areas have increased rapidly in
number and extent. Todd's maps show that ' imported ' cases of
the disease have occurred at many points along the eastern boundary
of the Congo State, in close proximity to the British and German
East African possessions, and that cases have already occurred at
Ujiji, on the eastern shore of Lake Tanganyika, in German territory.']
[Unless effective quarantine measures — such as those outlined by
Todd — dependent upon cervical gland palpation, be speedily intro-
duced and enforced, there is very grave danger of the disease being
carried into Nyassaland and other parts of British Central Africa, as
well as into areas of Uganda and German East Africa at present un-
affected. The danger is not only great but imminent, and prompt
and energetic action on the part of the Governments concerned is
imperative.]
For some years trypanosomiasis has made great ravages in
Uganda.^ [The disease appears to have broken out first in Busoga in
i8g6.^ Dr. Moffat, then Principal Medical Officer, Uganda and East
African Protectorates, explains its first appearance in Busoga by the
fact that a large number of Emin Pasha's Soudanese, with their wives
and followers, were brought into and settled in Busoga. They came
from the Congo Free State, where sleeping sickness has been endemic
for many years. Finding the necessary conditions present, the disease
rapidly spread, and in a few years became endemic around the
northern shores of the Victoria Nyanza — from Buddu on the west
to south of Kavirondo Bay on the east — in Busoga and Chagwe,
around Entebbe, and on the islands in the lake. The disease was
first definitely diagnosed by the Drs. Cook,* of the C.M.S. Hospital,
Mengo, in 1901, and so merciless has been its onslaught that it has
claimed probably more than 100,000 victims in Uganda alone during
the past six years (1901-1906).]
[The distribution of the disease in Uganda is peculiar. Except
in the district of Busoga, sleeping sickness has not become endemic
far from the shore of the lake or from the banks of rivers. The
villages along the lake shore and on the islands of the lake have been
most severely visited, many of them having lost two-thirds or more
of their inhabitants. The extent to which the disease spreads inland
from the lake differs in different parts and varies from ten up to thirty
or forty miles.]
^ [In a later paper Kinghorn and Todd {Lancet, February 2, 1907, p. 282) state
that the disease now extends much further south. It is now endemic along the
eastern shores of Lake Tanganyika, between about 4° and 7° S. Lat. Imported
cases have been reported from places even further south.]
^ Royal Society, Reports of the Sleeping sickness Commission. See reports by
Bruce, Nabarro, and Greig, by Low and Castellani, and by Christy.
3 [Hodges, Lancet, July 30, 1904, p, 290.]
^ [J. H. Cook, Journ. Trap. Med., July 15, 1901.]
364 TRYPANOSOMES AND THE TRYPANOSOMIASES
[Bruce, Nabarro, and Greig have shown that this pecuhar distri-
bution of the disease almost coincides with, and is probably dependent
upon, the distribution of a tsetse-fly — the Gl. palpalis. This fly is
found only near large water-courses where there is dense undergrowth
and shade, as from large trees ; it is not found in papyrus swamps or
in large open plains. For some reason at present unexplained, the
tsetse-fly has been found under other conditions in various parts of
Busoga, which no doubt is the cause of the greater area of endemicity
of sleeping sickness in that district than in other parts of Uganda.
Of course, there may be — and investigations by Nabarro and Grieg
concerning the shores of the Albert Nyanza and the banks of the
Nile to the north of this lake show that there are — uninfected fly
areas where sleeping sickness does not occur. An imported case of
the disease may be the means of making such areas endemic foci of
trypanosomiasis.]
Christy gives the following dates for the appearance of the disease
in different parts of Uganda : Several parts of Busoga or the island
of Buvuma, 1896 (Hodges); Kampala, February, 1901 ; South Kavi-
rondo, October, 1901 ; Sesse Islands, December, 1901 ; Kasagunga,
January, 1902 ; Lusinga Islands and Kasachonga, March, 1902 ;
Kisengere, May, 1902 ; and German East Africa, September, 1902.
According to these dates the disease is manifestly spreading, and
it is to be feared that the Uganda Railway, which runs from the East
Coast to Lake Victoria, will facilitate its spread, for Kisumu, the
terminus of the railway on the lake, is already infected. It is possible,
too, that the disease may spread to Egypt along the valley of the Nile.
[In 1903I Mr. Wyndham, of the Uganda Civil Service, found that
Gl. palpalis was prevalent on both shoreo (Uganda and Congo Free State)
of the Albert Nyanza, and since then the fly has been found between
Fajao, on the Victoria Nile, and the north end of the Albert Nyanza, as
well as at various places down the Nile, including the neighbourhood of
Wadelai and Nimule. The furthest point north at which Gl. palpalis was
met with by Hodges^ was near a small stream about thirty-five miles
south of Gondokoro, between Kanda and Shindiro.]
[Balfour^ states that Gl. palpalis has been found in the Lado Enclave
at Wandi, and also in the southern part of the Bahr-el-Ghazal province.
Another species of Glossina, Gl. morsitans, occurs in many parts of this
province — sometimes in very large numbers — and has been found by
Morant as far north as S. Kordofan.]
[When Gl. palpalis was first discovered in the region of the Victoria
Nile and around the Albert Nyanza in 1903, sleeping sickness was
unknown there. By the end of 1904, however, this fly area had certainly
become infected, for cases of sleeping sickness were seen by Greig* at
Fajao and at other places near the northern extremity of the Albert
Nyanza, and along the Nile as far north as Wadelai. Subsequently
1 [Nabarro and Greig, Report of Sleeping Sickness Commission, No. 5, pp. 46, 47.]
^ [Hodges, Report of Sleepiitg Sickness Commission, No. 8, pp. 86-99.]
^ [Balfour, Second Report of the Wellcome Research Laboratory, Khartoum,
1906 ; see p. 29 and map.]
* [Greig and Gray, Report of Sleepiiig Sickness Commission, No. 6, p. 276.]
HUMAN TRYPANOSOMIASIS 365
(1905) Hodges found that the disease had spread in this part of Uganda
(Unyoro) and in the Nile Valley ; but the conditions favourable to the
occurrence of a great epidemic such as that on Victoria Nyanzai are not
present in these parts of Uganda and the Nile Valley, except, perhaps, on
the shores of Lake Albert.]
[Sleeping sickness will probably make its wa}' down the Nile as
far as Gl. palpalis extends, but the danger of its spreading to Egypt
is not great, because this tsetse has not been found along the Nile
north of Gondokoro ; nor is it likely to occur here, for the character of
the country is unfavourable to the fly (Greig). We know, however,
that several other species of tsetse-fly occur in the Anglo-Egyptian
Sudan, in British and German East Africa, in British Central Africa,
and as far south as Natal and the Transvaal. If, as appears highly
probable from the experiments of Nabarro, Greig, and Wiggins in
British East Africa, other species of Glossina than Gl. palpalis can act
as carriers of T. gambiense, there is grave danger of sleeping sickness
spreading east to the coast, north into the Sudan, and south through
British Central Africa even as far as the Transvaal. The most
stringent precautions and energetic measures should be taken to
prevent the infection of this enormous fly-belt by natives from the
endemic foci in Uganda and the Congo State.]
[In November, 1903, Nabarro saw a case of sleeping sickness,
which had been imported from Uganda, in the hospital at Nairobi,
British East Africa, but hitherto the disease is unknown amongst the
Nandi and Masai tribes of British East Africa.]
[In September, 1904, Dr. Ahlbory,^ in writing from Muanza,
German East Africa, states that sleeping sickness and Gl. palpalis
occur on the Gori River ; also that an imported case of sleeping sick-
ness from Uganda had been observed in Muanza. He states further
that trypanosomiasis had been discovered in a child of two born
in Tabora, which had never left the districts of Unyamwezi and
Ussukuma.^j
[A European who contracted the disease in German East Africa
recently died in Hamburg.* All these facts show that trypano-
somiasis is obtaining a footing in this German colony,, which has
1 [Hodges gives the following as being the conditions necessary for the occur-
rence of a great epidemic : (i) The presence of Gl. palpalis in large numbers over
a considerable area ; (2) a thickly-gathered, numerous population ; (3) free and
frequent intercommunication, much of it within the fly range ; (4) a considerable
part of the population either living or daily employed within the fly range ; (5) a
coast or banks much broken by inlets, estuaries, and rivers, and with adjacent
islands. These conditions rarely coexist in such fatal completeness as they do
round the northern shores of Victoria JNyanza (Hodges).]
^ [See R.A.M.C. Jotirn., v. 4, 1905, p 124.]
2 [For the latest information concerning the progress of sleeping sickness in
Uganda and German East Africa, consult the Reports of H.M. Commissioner for
the Uganda Protectorate, also Koch in the Supplement to No. 51 of the Deutsch.
med. Wochenschr., December, 1906.]
* [Nocht and Mayer, in Kolle and Wassermann's ' Handbuch der Pathogenen
Micro-organismen,' Appendix, p. 56.]
366 TRYPANOSOMES AND THE TRYPANOSOMIASES
probably become infected both from Uganda and from the
Congo.i]
We may summarize the information we already possess about the
geographical distribution of this disease by saying that it extends
along the valleys of the Senegal, Niger, Congo, and Upper Nile, and
occurs also in the valleys of less important rivers situated between
them (Manson). Hitherto the disease has not been recorded either
in North or South Africa.
Section 3. — Predisposing" Causes. The Influence of Age, Sex,
Occupation, Race, etc.
Age appears to have no marked influence upon the disease.
Christy has seen symptoms of sleeping sickness in many infants of
eighteen months to two years, and these children had become infected
a considerable time previously.^ [By gland puncture Button and
Todd, on the Congo, found trypanosomes in an infant less than nine
months old.] The two sexes are attacked in the same proportion.
The influence of occupation and social position is very marked. The
majority of cases are seen amongst the agricultural workers and
amongst the poorest classes. The native chiefs and persons belong-
ing to the upper classes living in the villages are attacked in a much
smaller proportion than the poorer negroes who work in the fields
all day.
For a long time it was believed that the disease attacked only
negroes. In 1859 Chassaniol reported a case of the disease in
a mulatto at Goree. In Portuguese Congo half-castes are often
attacked (Bettencourt). The cases recorded by Button and Todd,
Manson, Broden, Brumpt, and others, show that trypanosomiasis does
' [Kudicke (Centrxlb.f. Bakier., I, Orig., v. 41, igo6, p. 72) has described a case
of human trypanosomiasis in a native of German East Africa, apparently not due
to T. gambiense. Clinically the patient was in the first stage of trypanosomiasis :
febrile attacks not responding to quinine, enlarged lymphatic glands, pulse- rate
increased, and spleen slightly enlarged. Occasionally there were slight fibrillary
tremors of the tongue and difficulty with speech ; once there was an urticarial
eruption, which did not irritate, and soon disappeared. Trypanosomes could not
be found in blood-films, but a Cercopithecus injected with 9 c.c. blood showed very
few trypanosomes in its blood seventeen and twenty-one days after injection. The
monkey died of sepsis a few days later. Rats, monkeys, and a cow injected with
the monkey's blood all failed to become infected. The trypanosome was con-
siderably larger and broader than T. gambiense ; the posterior end was very
pointed, and the oval nucleus was situated at the junction of the middle and
posterior thirds of the body. The parasites were all alike, and resembled
T. theileri, but were rather smaller, and the undulating membrane was better
developed. The patient was treated with arsenic for a time, and the febrile
attacks ceased. The after-history of the case is unknown.]
[Todd and Tobey (Liverpool School of Tropical Medicine, Mem. 21, Sep-
tember, 1906, pp. 93, 94) describe a very similar trypanosome which was observed
in the fresh blood of two monkeys (Cercopithecus schmidti) at Kasongo, Congo
State. The trypanosomes were not found in stained specimens. Todd and
Tobey think it is a hitherto undescribed parasite of the monkey, and that it is the
same as that seen by Kudicke.]
''■ Christy, ' The Epidemiology and Etiology of Sleeping Sickness.' Royal
Society, Report of the Sleeping Sickness Conmiission, November, 1903.
HUMAN TRYPANOSOMIASIS 367
not spare Europeans. We have already seen that in a case of
Sir Patrick Manson's the characteristic symptoms of sleeping sick-
ness were observed in a white woman.
In 1904 Dupont/ a practitioner from the Congo Free State,
recorded three cases of sleeping sickness in Europeans who had lived
on the Congo. Trypanosomes were found in the cerebro-spinal fluid
of only one of these patients, but in the other two cases the clinical
symptoms pointed clearly to the existence of sleeping sickness.
[During the last few years several more cases of trypanosomiasis
and sleeping sickness have been recorded in Europeans. Nearly all
the European countries with African colonies have contributed to the
ever-increasing list of victims to this disease. A recent writer^ in the
British Medical Journal states that hitherto seven cases of trypano-
somiasis are known to have occurred amongst English people. Four
of these have died ; of the three still alive, one is said to be quite
well and the parasite has disappeared, while the other two have been
free from active symptoms for several months. The writer of the
article — and Sir Patrick Manson is of the same opinion — thinks that
there may be a small percentage of recoveries from trypanosomiasis in
man, and that the terminal and fatal condition— sleeping sickness —
is not inevitable.]
[Two of these cases are of more than ordinary interest. One was that
of a European who was under the care of Dr. Moffat in Entebbe,
Uganda, in March, 1903, as already recorded by Bruce and Nabarro in
their 'Progress Report on Sleeping Sickness in Uganda,' p. 17. This
patient was curator of the Botanical Gardens, which are situated on the
lake shore, and are full of tsetse-flies and rank vegetation. The disease
started with irregular fever and delirium ; no malarial parasites were seen
at any time, but trypanosomes were discovered in the blood on April 2,
1903. The patient was invalided to England on April 6, and died exactly
three years later — on April 6, 1906 — of typical sleeping sickness.]
[While in England the patient had periodical febrile attacks. He first
became drowsy in November, 1904, having previously suffered from
delusions. Latterly he became more drowsy and apathetic, and was
admitted to hospital for the third time in October, 1905.8 He was then
very weak and had difficulty in swallowing his food. While in hospital
he was sometimes very lethargic, not speaking for days, while at other
times he brightened up and took his food well. On several occasions his
temperature rose to 103° or 104° F., accompanied by a rigor or fit, epileptic
in character. Neither trypanosomes nor malarial parasites were found in
the blood on these occasions. On March 28, 1906, the temperature fell to
92° F., but rose again to 98° F. a few days later. It then steadily and
progressively fell, and on the day of death — April 6, 1906 — was 84-2° F.
On April 4 he was very drowsy, but still sensible. In the evening he had
a fit, which lasted about ten minutes. The next day he was almost uncon-
scious, but winced when lumbar puncture was performed. Trypanosomes
1 Dupont, Le Caducie, April i6, 1904.
2 [Brit. Med. Journ., May 5, 1906, p. 1062.]
2 [I am indebted to Dr. Rose Bradford, under whose care the patient was while
in University College Hospital, for permission to use the notes of the case, and
to make the post-mortem bacteriological investigation.]
368 TRYPANOSOMES AND THE TRYPANOSOMIASES
were easily found in the cerebro-spinal fluid. The next day the patient
died, and post-mortem the brain showed the typical macroscopic
appearance of sleeping sickness, and there were broncho-pneumonic
patches in both lungs. The heart blood and cerebro-spinal fluid were
found to be sterile.J
[Dr. Mott, who examined the brain and other organs microscopically,
found the typical lesions of sleeping sickness present.]
[The other case was that of a young scientist, i a member of the Royal
Society's Sleeping Sickness Commission in Uganda, who cut himself
during the dissection of an infected rat. Trypanosomes soon appeared in
his blood, and after an unusually rapid course, the infection ended fatally
in June, 1906, having lasted only a few months.]
[Records of other recent cases of trypanosomiasis in white people
have been summarized by Mesnil.^ These cases have been reported
by Carlos Franga,^ Dias de Sa,* Martin and Girard,^ Sicard and
Moutier,^ and Willems.''' In all but Dias de Sa's case, in which
hypnotic symptoms were absent throughout, these were all cases of
sleeping sickness. Willems mentions four cases which came under
his observation. There seems to be no doubt about the diagnosis, as
the symptoms were very definite, but the diagnosis was not confirmed
microscopically. In all the other cases trypanosomes were found in
the body fluids of the patients or in the blood of injected animals.]
[Other cases have been recorded by Broden^ in a missionary from
the Congo, and by Gtinther and Weber® in a patient who probably
contracted the infection in Cameroon in 1902. Reference has already
been made to the case of a European who became infected in German
East Africa and died recently in Hamburg.]
[Nabarro and Greig^" have recorded the case of a Persian — the
first reported instance of the disease in an Asiatic — who, having been
in Uganda on and off for eighteen years, had come into close contact
with the natives and contracted sleeping sickness, of which he died
towards the end of 1903 (see Fig. 51). Two cases of trypanosomiasis
have recently been observed by Gray in Indian soldiers in Uganda.]
The seasons appear to exert no influence upon the course of the
disease, but on account of the long period of incubation, or rather
of latency, which, as a rule, precedes the appearance of nervous
symptoms, it is difficult to be sure about this.
We have already mentioned that the disease has been wrongly
^ [I refer to the late Lieutenant Forbes TuUoch, R.A.M.C, whose untimely fall
on the field of battle against disease is deplored by all.]
^ [Mesnil, Bi/I/. Inst. Past., v. 4, 1906, p. 126, from which the following five
references are taken.]
^ [Carlos Franca, quoted from Le Semaine me'dicale, 1905, p. 48.]
* Dias de Sa, Porto medico, 1905, No. 2.]
* [Martin and Girard, Bull, medic, April 29, 1905 ; Lancet, May 20, 1905,
p. 1385 ; also L. Martin, Ann. Inst. Past., v. 21, 1907, pp. 161-193.]
" [Sicard and Moutier, Bull. Soc. 7ned. des Hopitaux, June 30 and December 8,
1905.]
' [Willems, ' La Maladie du Sommeil,' Brussels, 1905.]
' [Broden, Publications de la Soc. dEtudes colon, de Belg., 1905.]
" [Gtinther and Weber, Miinch. med. Woch., June, 1904, pp. 1044-1047.]
" [Nabarro and Greig, Sleeping Sickness Reports, No. 5, 1905, p. 33.]
HUMAN TRYPANOSOMIASIS 369
attributed to manioc-eating. Fish, or at least certain kinds of fish,
has often been mentioned amongst the causes of the disease, on
account of the frequency of its occurrence along the banks of certain
watercourses and, in Uganda, in the villages bordering on Lake
Victoria. But in certain districts where the natives eat as much,
and the same kinds of, fish as in the infected districts the disease is
not endemic.
Wars and famine have favoured the spread of sleeping sickness
in Africa. This is the usual effect of these scourges upon epidemic
diseases, and sleeping sickness, naturally endemic, may assume an
epidemic form.
The Soudanese soldiers disbanded after the relief of Emin Pasha
by Stanley in 1888 contributed, according to Christy,^ to the rapid
spread of the disease throughout Uganda. In igoi and 1902,
according to the same observer, the mortality from this disease was
increased by famine in the islands in Lake Victoria.
Along the Ivory Coast, before its invasion by bands of Samori,
sleeping sickness was much less common than it is at the present
day (Kermorgant).
The chief foci of the disease are met with along the rivers in well-
wooded districts. This is easily explained. We shall see later on
that sleeping sickness is spread by a biting fly, Gl.palpalis, and that
this fly lives along the watercourses in districts where vegetation is
abundant. When patients suffering from trypanosomiasis arrive in
those areas where Gl. palpalis abounds, the disease is spread; on
the other hand, in districts where the fly is absent the introduction
of infected individuals is followed by no serious result. It is just the
same as with malaria, yellow fever, nagana, and, in short, with all
diseases which are propagated by a special insect : the disease is
infectious only where the insects capable of propagating it occur.
Section 4. — Description of the Disease.
All authors are agreed that the onset of the disease is insidious.
We know that trypanosomes may be present for a long time in the
blood before getting into the cerebro-spinal fluid, and thus giving rise
to the symptoms of sleeping sickness, so that two distinct stages
can be recognised during the course of the disease.
In the first stage trypanosomes occur in the blood, but usually
only in small numbers. Generally they give rise to no symptoms in
negroes, but in white people there is irregular fever. In the second
stage pain in the back, tremors, and, later, drowsiness occur, and the
temperature is of a hectic type. The drowsiness goes on to lethargy,
and the patient finally falls into a comatose condition. The tem-
perature becomes subnormal before death. Trypanosomes are prac-
tically always present in the cerebro-spinal fluid.
' [Christy obtained this information from Dr. Moffat ; see p. 363.]
24
370 TRYPANOSOMES AND THE TRYPANOSOMIASES
Hitherto the descriptions of sleeping sickness have referred only
to this second phase of the disease.
First Stage [Trypanosome Fever, so called.] — In negroes
the diagnosis could formerly only be made by the examination of the
blood. The parasites are very scanty, and therefore often difficult to
discover in the blood. [Mott was the first to suggest that possibly the
trypanosomes might be more easily found in the enlarged lymphatic
glands than in the blood. Greig and Gray, in Uganda, practically
tested Mott's suggestion, and found that trypanosomes v^'ere often
discernible in the fluid obtained by gland puncture when they could
not be seen in the blood. Gland puncture is therefore the best
means of making the diagnosis of early trypanosomiasis, but in the
absence of the necessary apparatus and skill, gland palpation may be
relied upon almost as much. Dutton and Todd have found that
cervical gland enlargement, without obvious cause, in a native who
has been exposed to the risk of infection, is almost certainly due to
trypanosomiasis, and should be regarded as such until the contrary
is proved.]
This latent period of the infection varies very much in length :
sometimes it is very short ; at other times it may extend over several
years. [In a case of trypanosomiasis in a European contracted on
the Congo, Dutton, Todd, and Christy^ found 'that the incubation
period between the time of infection with T. gambiense and the
appearance of the symptoms associated with trypanosomiasis may
be as short as four weeks.']
According to Corre, the inhabitants of the island of Goree
(Senegal) who. had lived in Casamance did not consider themselves
safe from the disease until at least seven years after they had left the
infected area. Gu6rin, in the Antilles, has recorded cases in negroes
who had quitted Africa five to eight years previously, and there is
no doubt that these negroes had brought the germ of the disease
from Africa. The disease, however, never spread in the Antilles.
Manson writes : ' The disease may appear seven years after having
left an endemic area.'
The observations of Dutton and Todd in Gambia, and of Bruce,
Nabarro, and Greig in Uganda, show that in negroes this first stage
is accompanied, as a rule, by no obvious signs of disease [except the
glandular enlargement above referred to] ; but this is not the case
with mulattos and whites. Fever is the chief sign of the infection.
The patients suffer from an irregular intermittent fever, the tempera-
ture being raised for two to four days, then falling to normal or
below normal for four or five days. In other cases the fever is of the
hectic type, the temperature being normal in the morning, but rising
in the evening to 38'5° or 39°C., and rarely to 40° C. [104° F.].
The rises of temperature are not preceded by rigors, and the sweat-
1 [Dutton, Todd, and Christy, Thompson Yates and Johnston Lab. Reports,
V. 6, part i., 1905, section 6.]
HUMAN TRYPANOSOMIASIS
37^
ing which occurs at the end of the rise is, as a rule, only slightly
marked. The respiration and pulse rates are increased quite apart
from the febrile attacks ; the respiration rate is from 25 to 30 a
minute, and the pulse rarely falls below go. Cardiac excitability
is, according to Broden, a constant symptom, the pulse rate often
reaching 140 a minute.
Localized oedemas and erythemas are often present, such as
puffiness of the face, oedema of the eyelids and ankles, and evanescent
congested or erythematous patches on the face, trunk, or limbs.
Anaemia, general weakness, and wasting are slightly marked at first,
but gradually increase, and headache is present in many cases.
The spleen is often enlarged, but this is not always the case,
FaJiT
r-IOZ°
-101'
-100'
-33'
-98'
-37'
-96'
-Human Trypanosomiasis. Part of the Temperature Chart of Button's
First Patient during his Stay in the Liverpool Hospital.
Fig. 48.-
especially at the outset. Baker observed splenic enlargement in only
one of his three cases. Broden also thinks that the spleen is only
shghtly enlarged in the first stage of the disease. Moreover, the
prevalence of malaria in those districts where trypanosomiasis
occurs may itself give rise to enlargement of the spleen. The liver
dulness is increased in some cases. In the absence of complications,
the other organs show nothing abnormal.
In Dutton's first case the duration of the disease was at least
nineteen months before it ended fatally. Button and Todd's case in
a quadroon also ended fatally after one year and a half.
In certain cases trypanosomiasis may terminate fatally without
giving rise to the characteristic symptoms of sleeping sickness —
symptoms which may occur in Europeans and Asiatics as well as in
blacks, as is shown by the very interesting case published by Manson
in 1903 [and by the later cases], to which we have already referred.
Second Stage [Sleeping Sickness, so called.] — The chief
signs are fever and symptoms associated with the nervous system.
The temperature, which in the first stage of the disease shows
considerable elevations, with fairly long intervals of apyrexia, is in the
second stage of a hectic type. As a rule, considerable oscillations
24 — 2
372 TRYPANOSOMES AND THE TRYPANOSOMIASES
are observed, the temperature in the evening often rising to 39° C.
[i02-2° R], and falling in the morning to 37° C. [98-6° F.]- It is
important to bear in mind this type of fever, for the diagnosis has
often to be made between trypanosomiasis and malaria. In malaria
we know that, as a rule, the highest temperatures are observed in
the morning, whereas in trypanosomiasis and in ' hectic ' fever the
reverse is the case.
The rise of temperature is, as a rule, unaccompanied by rigors or
sweating. Patients will sometimes attend to their daily occupation
with a temperature of 39° to 39'5° C. [102° to 103° F.], and it is
therefore necessary to use a thermometer in order to ascertain
whether the temperature is raised, and not to rely upon the state-
ments of patients.
The pulse-rate is increased, and, moreover, may vary consider-
ably in frequency during the day, increasing, perhaps, from 90 to 130
per minute, without a corresponding rise in the temperature. The
respiration rate is also increased to 20 or 30 per minute. There are
often irregularities in the temperature chart due to complications,
and particularly to malarial attacks. For several weeks before death
the temperature falls below normal, and this subnormal temperature,
when it occurs in the evening as well as in the morning, is always of
fatal import. Fig. 49 shows a typical temperature chart of a sleep-
ing sickness patient. [During the last seven to fourteen days the
rectal temperature often falls to below 95° F. (35° C), and for
several days may be as low as 92° F. {33'3° C.) in the morning. In
the case of the European mentioned on p. 367, the temperature
steadily fell from 95° F. during the last five days of life, and shortly
before death reached the very unusual figure of 84'2° F. (29° C),
taken in the rectum.] With this fall of temperature the frequency
of the pulse and respiration is usually diminished.
Headache and a change in the mental condition or temperament
of patients are constant symptoms at the commencement of the
second stage of the disease. Headache occurs in the supra-orbital
regions ; some patients complain of a sense of constriction in the
, ternples (Gu^rin). The headache is often accompanied by pain in
the back and in the upper part of the chest. ^ Patients who were
active and intelligent become lazy and dull. Apathy is one of the
chief features of the disease; the face loses its ordinary expression,
and the patient is drowsy, and when asked questions replies only
after a considerable mterval. [Figs. 50 and 51 show very well the
characteristic expression and facial aspect in sleeping sickness.]
Tremor of the tongue and hands is nearly always present. In
the tongue it is usually of a fibrillary character. The tremor of the
hands and arms which is present during rest often becomes increased
on voluntary movement, such as raising a glass of water to the lips,
1 [In two cases recorded by L. Martin pain in the feet was a very marked and
persistent symptom.]
HUMAN TRYPANOSOMIASIS
373
etc. In certain cases tremors also affect the lower limbs and trunk,
and may even shake the bed on which the patient is lying.
Towards the end rigidity of the neck muscles and marked
flexion of the lower limbs are frequently observed. Epileptiform
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428 TRYPANOSOMES AND THE TRYPANOSOMIASES
[Treatment of Experimental Nagana in Mice. — Mesnil and
Nicolle studied a very large number of synthetic compounds,^ with
the view of ascertaining which were the best bases and substitution
products, and which the best lateral chains. Reviewing first the
symmetrical diazo compounds, let us enquire what is the respective
influence of the lateral chains and of the diazos on the curative
power.]
[Experiments show that the benzenic chains (even combined
with the best bases) always give rise to inactive derivatives. So
also do the naphthalenic chains which do not contain the NHg
group, or which, containing it, do not present at least two SO3 H
groups. On the contrary, it is amongst the naphthylamine-disulpho
compounds, the disulphonic amino -naphthols, the disulphonic
naphthylene diamines, and the trisulphonic naphthylamines that
active chains are found. Amongst the disulphonic a -naphthylamines
the best type is i, 5, 7 ; amongst the disulphonic ^-naphthylamines
the best types are i, 5, 7, and especially 2, 3, 6, the lateral chain of
trypanred. Amongst the disulphonic amino-naphthols the best
types are 1,8,4,6 (acid K), and especially 1,8,3,6 (acid H).
Amongst the disulphonic naphthalene diamines the best type is
2,7,3,6. The a- and /S- trisulphonic naphthylamines are very in-
ferior to the corresponding disulphonic derivatives ; the addition of a
third sulpho-group is, therefore, harmful rather than beneficial.]
[Each of the good lateral chains was studied in combination with
a number of diazos (as many as twenty-seven for acid H), and it was
found that, according to the base used, the activity of the resulting
derivatives varied from o to oo •^]
[Acid H, like all the disulphonic amino-naphthols, can be united
with the diazos in an acid as well as in an alkaline medium. In an
acid medium the mode of insertion of the azo group is completely
inverted, and the therapeutic power is much diminished. It is easy
to unite two molecules of acid H successively in an acid and alkaline
medium ; the asymmetrical colours thus formed manifest an efficacy
varying with the base selected.]
[The conditions affecting the activity of the lateral chains
were also studied in detail ; it was found that the best of these
chains were those which contain the sulpho-groups 5,7 ; 4,6 ; and
especially 3, 6.]
[What part do the diazos play in the efficacy of these colours ?
Mesnil and Nicolle found that the benzidinic bases are the only ones
of any value; but their activity depends upon a number of con-
ditions, (i) On the position of the diazotizable NHj group; the
meta-position (in relation to the benzidinic link) is bad ; the ortho-
1 [The authors express their indebtedness to several dye works, and especially
to the Farbenfabriken at Elberfeld, for supplying the dyes.]
2 [By CO is meant that a permanent disappearance of the trypanosomes
followed a single injection of the dye.]
THE TREATMENT OF THE TRYPANOSOMIASES 429
position, on the other hand, is good. (2) On the general structure
of the diazo ; the benzidinic nuclei, strictly speaking, always appear
better than the bases in which the two hexagons, instead of being
directly linked, are joined by a bivalent group or atom (as in
p-diamino-diphenylurea ; see p. 427). Benzidine is, on the whole, a
good nucleus. In its derivatives the activity varies with the position
and nature of the substituting groups or atoms. Thus, to mention
two of the many facts ascertained by the authors, it was found
(i) that the ortho-position (in relation to the benzidinic link) was
always bad ; and (2) that the substituting groups CH3 and OCH3, as
a rule, exerted a favourable influence.]
[To determine with any degree of completeness the influence of
the lateral chains on the bases, it would have been necessary to
experiment with thousands of compounds. With the resources at
their disposal Mesnil and Nicolle were able to arrive at at least one
of the laws which regulate this influence. This is the law : On
classing the three most commonly used bases in the following order,
benzidine, dianisidine, tolidine (B, D, T), it is found that when a
lateral chain possesses a sulpho-group in position 6, the activity of
the, compound resulting from the union of this chain with one of the
three bases increases from B to T ; when the lateral chain possesses
a sulpho-group in position 7, the activity of the compound diminishes
from B to T. This law of the sulpho-groups 6 and 7 also applies to
other bases than benzidine, dianisidine, and tolidine.]
[No doubt there are other laws governing the formation of active
compounds, because it is not sufficient to combine any good chain
with any good base in order to produce an active compound.]
[Theoretical considerations, which are given at length in Mesnil
and Nicolle's paper, led these authors to conclude that the auxo-
chrome NHj constitutes the essential element of the lateral chains.
The group NHg is also present in other colours used by certain
investigators (notably methyl and ethyl green), as well as in normal
serums.]
[The derivatives, which are active in vivo against nagana, are
solutions having a blue, violet, rose, or red colour ; they are trans-
parent or opaque, and colour the mice more or less permanently ;
they are quite harmless in the therapeutic dose (o'5 to i centi-
gramme), and often in larger doses. The best of these derivatives
is ' dichlorobenzidine-|-acid H— alkaline, alkaline' (called CI for
short — bluish violet in solution). Then come the compounds
' tolidine -1- acid H — alkaline, alkaline ' (called A^ — violet solution), and
1 [Bouffard (Ami. Inst. Past., v. 20, 1906, pp. 539-546) has studied the distri-
bution of this dye in the organs and tissues of healthy animals injected with it
in vivo. He finds the dye in the convoluted tubules of the kidney, in the cells
of Kuppfer of the liver, and in the interstitial cells of various organs and tissues.
The cerebro-spinal fluid remains uncoloured. This seems to show that the dye,
and probably, therefore, other remedial agents, are unable to penetrate the spinal
canal, at least in certain cases. It suggests an intraspinal method of treatment
for sleeping sickness, in addition to subcutaneous or intramuscular medication.]
430 TRYFANOSOMES AND THE TRYPANOSOMIASES
'tolidine + acid H-acid, alkaline' (called A'— violet). These three
dyes can, in many cases, bring about the permanent disappearance
of the trypanosomes after a single injection. Such results are only
rarely obtained with the compound ' benzidine + 2, 7 diaminonaph-
thylene — 3, 6 disulphonic acid' (called a for short — dark cherry- red
solution), and quite exceptionally with trypanred — 'benzidine
o-monosulphonic acid + acid R' (clear cherry-red solution), and with
the compound 'p-diamino-diphenylurea-|-acid H' (called Ph— violet).]
[The treatment of relapses is only successful with the compound
Ph. This dye is able to prevent the reappearance of the parasites
when a full initial dose is injected, followed in a week by a smaller
dose. Finally, it was found that the dyes CI and A possessed a
remarkable preventive power against the infection (nagana).]
[Mesnil and Nicolle state that the asymmetrical diazo compounds
offer no advantage over the symmetrical, but rather the reverse ;
and that triazo and polyazo compounds never manifest any curative
power, even when they contain good lateral chains.]
[In the second part of their paper^ Mesnil and Nicolle give a
detailed account of the therapeutic action of the six best dyes, and
also compare their action with that of some arsenic compounds.
About one-third of the mice treated with CI, A, and A' were per-
manently cured by one injection (dose i centigramme for a mouse of
15 to 20 grammes) ; so also were one-quarter of those treated with
a (dose 0'75 centigramme) ; one out of thirteen treated with trypan-
red (dose 0'5 centigramme) ; and one out of fifteen treated with Ph
(dose I centigramme). The dyes were always dissolved in distilled
water (r per cent, solution), and injected hypodermically.]
[In the cases Vi'hich were not permanently cured a relapse
occurred after a variable time (five to twenty days, average twelve
days). A relapse, if untreated, ran the same course as an original
infection. Few dyes were found of use in the treatment of relapses ;
as has been mentioned, Ph alone gave good results, and then only if
the relapses did not occur very soon after the treatment.]
[Of the arsenic derivatives used, a certain number (arsenite and
arseniate of soda, arrh^nal, and atoxyl), given in suitable doses,
caused the trypanosomes to disappear : but relapses always occurred
rapidly, except with atoxyl, which behaved like the dye a (two mice
out of eight cured by one injection). Atoxyl was also preventive,
almost as much as CI.]
[The Disappearance of the Trypanosomes. — The parasites disappear from
the blood in sixteen to seventy-two hours, according to the nature and dose
of the dye used, and the number of parasites present when the injection
is given. The trypanosomes in the circulating blood show involution
forms ; they become granular, stumpy, and increasingly sluggish ; their
remains are found in the leucocytes. In vitro these dyes do not exhibit
any appreciable trypanosomicidal activity.]
1 [Mesnil and Nicolle, Anu. Inst. Past., v. 2), July, 1906, pp. 513-538.]
THE TREATMENT OF THE TRYPANOSOMIASES 431
[The investigations made to try to find out what becomes of the
trypanosomes from the time that they disappear from the blood to the
time the relapse occurs were carried out on mice treated with A and Ph.
It was found that, even on inoculating a number of mice with the blood,
spleen, liver, kidneys, and brain of mice killed some days after the
disappearance of the trypanosomes, the parasites were not always found
in the inoculated animals, although, as has been pointed out above, a
relapse would almost certainly have occurred in the mice treated with
the dye. This failure to find the trypanosomes in the subinoculated mice
is due to their small numbers, or to their physiological condition, or to
some unknown cause. In one interesting case the brain alone was
infective.]
[The Treatment of Experimental Caderas in Mice. —
The comparative study of the therapeutics of nagana and caderas
shows at once that the order of activity of the dyes is subject to
important variations on passing from one trypanosomiasis to another.
Mesnil and Nicolle's observations, corroborated by those of Wenyon
for T. dimorphon, show that this variation depends on the structure
of the lateral chains, and especially of the diazos.]
[In caderas, as in nagana, the dye CI causes the complete dis-
appearance of the trypanosomes in many cases (about 50 per cent.)
after a single injection. Trypanred also gives good results, as
Ehrlich and Shiga had originally shown (almost 50 per cent.). The
dyes A, A', and a cure only exceptionally, and Ph never.]
[The interval between the treatment and the relapse (when this
occurs) is about the same as with nagana, except in the case of
trypanred, when, according to Ehrlich and Shiga, it may be as long
as two months. The treatment of relapses is successful with CI,
trypanred, and, above all, with a.]
Treatment of Experimental Surra in Mice. — Here again
the best colour is CI, which cures nearly all the animals after one
injection. After this comes trypanred. The curative power of A
and A' is doubtful, that of a and Ph inefficient. The derivative CI
has a prophylactic action which is quite remarkable.]
[To summarize the foregoing observations, we may say that CI
(dichlorobenzidine + acid H) constitutes, at the present time, the best
chemical agent to oppose the three animal trypanosomiases, nagana,
caderas, and surra ; but for the relapses Ph is to be recommended
in nagana, a in caderas, and perhaps atoxyl in surra.]
[Treatment of Experimental Trypanosoma dimorphon In-
fections IN Mice. — In the treatment of the three above-mentioned
trypanosomiases the best lateral chain is acid H, and the best diazo is
dichlorobenzidine. The blue dyes are therefore, as a rule, better
than the red dyes. In T. dimorphon infections, however, Wenyon
found that the opposite condition holds. The only derivative capable
of curing mice after a single injection was the compound a. Try-
panred, administered even in repeated doses, was only exceptionally
able to prevent the reappearance of the parasites. With the other
432 TRYPANOSOMES AND THE TRYPANOSOMIASES
derivatives relapses always occurred, sometimes, however, after a
long interval.]
[Treatment of Experimental Infections with Trypanosoma
GAMBiENSE IN Rats AND MoNKEYS. — In these cases it is impossible to
obtain a permanent cure after a single injection of the dye. The
relative value of the drugs used is estimated by the interval which
elapses between the treatment and the relapse. The most efficacious
dye was found to be Ph ; after this come the compounds ' p-diamino-
phenylglycolether^ + acid H ' and CI ; then, a long way behind, comes
trypanred, and further still the compound a. We see, therefore,
that in T. gambiense infections, as in nagana, caderas, and surra, the
best lateral chain is acid H ; but, whereas in the last three diseases
the best diazo is dichlorobenzidine, for T. gambiense it is p-diamino-
diphenyl urea. As has already been mentioned, the best drug in
T. dimorphon infections is a — a red dye. ' It is permissible to hope,'
say Mesnil and Nicolle, ' that we shall one day arrive at a means of
distinguishing the various pathogenic trypanosomes by the chromo-
therapeutic test.']
[Parallel experiments were made with atoxyl and sodium arsenite.^
With the former permanent cures were occasionally obtained after a
single injection in the monkey and rat. As in the case of the other
trypanosomiases, sodium arsenite is far inferior to atoxyl in treat-
ment.]
[Having ascertained that the two best drugs were the dye Ph and
atoxyl, Mesnil, Nicolle, and Aubert used them in different ways in
order to find out how the best ultimate results could be obtained.
The alternate use of the dye Ph and of atoxyl was found of more
value that either drug used singly ; in some cases the relapses were
treated only as they occurred, in others preventive injections were
given, so as to try and ward off a relapse.]
[A rat which received four injections of Ph (each time on the appear-
ance of trypanosomes in the blood) lived for 143 days ; a control rat died
in forty-seven days. Another rat which received seven injections was still
alive after eight months ; trypanosomes were absent from the blood for
three and a half months after the last injection of Ph. A rat treated with
atoxyl had a relapse after twenty-two days ; a fresh injection of atoxyl
cured the animal, for no relapse had occurred when the rat died, 147 days
afterwards. Another rat injected with atoxyl had a relapse after 115 days.
Two rats which were injected only once never showed trypanosomes,
although they survived 121 and 171 days.]
The preventive treatment of relapses gave even better results,
especially with Ph. It is interesting to note, however, that in some
cases relapses occurred after a very long interval — as much as six
months. These delayed relapses in rats show that under the influence
1 [This is perhaps more correctly called p-aminophenyl-diether of glycol. For
its formula see p. 427.]
2 [The dyes were used in 1 per cent, solution in distilled water ; the atoxyl in
2 per cent, solution ; and the sodium arsenite 1 per 500.]
THE TREATMENT OF THE TRYPANOSOMIASES 433
of treatment a subacute disease maybe converted into a chronic one,
and also that one must be very careful in speaking of cures where
T. gambiense infections are concerned.]
[In monkeys the best results were obtained by using atoxyl alone,
or the combination Ph-atoxyl alternately, and without waiting for a
relapse to occur before injecting a further dose of the drug. Animals
treated with Ph alone were never permanently cured ; but by means
of atoxyl, or of atoxyl and Ph used alternately, the trypanosomes
disappeared from the blood and remained absent for five or six
months (experiments still in progress). Mesnil, Nicolle, and Aubert
think that some of these monkeys were really cured, for the following
reasons: (i) For five months or more after the last treatment
trypanosomes had not reappeared in the blood ; (2) the blood of
two of the monkeys was not infective for rats in 8 c.c. doses ; (3) the
whole of the blood and the extracts of organs of another monkey failed
to infect a dog ; and (4) the bloods of all the monkeys lost the power
of agglutinating their own red corpuscles. Time will show whether
these monkeys are permanently cured of their trypanosomiasis.]
[These drugs, in therapeutic doses, are well borne by monkeys,
and no doubt the same applies to human beings. As we shall see in
the next section, atoxyl is the only drug which is at present receiving
the serious attention of investigators in the treatment of human
trypanosomiasis. In the case of negroes the alternate administration
of atoxyl and the dye Ph may prove superior to atoxyl alone ; but in
whites the violet coloration of the integuments produced by the dye
will be a bar to its general use.]
Section 5. — Treatment of Human Trypanosomiasis (Sleeping-
Sickness) and of Experimental Infections with Trypano-
soma gambiense in Animals.^
[Before it had been discovered that T. gambiense was the cause of
sleeping sickness. Low and Castellani treated their cases in Uganda
with iron, quinine, and arsenic. This produced a distinct but
temporary improvement, especially in cases complicated with
malaria.]
[When the probable role of the trypanosome in the causation of
the disease was demonstrated by Castellani, Bruce, and Nabarro,
treatment by injections of arsenic and other drugs, which had proved
of some value in nagana and surra, suggested itself. Nabarro and
Greig, in 1903, treated a patient by intravenous and intraspinal
injections (8 c.c. dose in each case) of a i per cent, solution of
methylene blue. No permanent benefit resulted from this treat-
ment. Two other patients in an early stage of sleeping sickness were
'- [Laveran has recently given a good rdsum^ of the various attempts that have
been made to treat human trypanosomiasis. See Bu//. de PAcad. de Med.,
February 26, 1907.]
28
434 TRYPANOSOMES AND THE TRYPANOSOMIASES
treated by intramuscular injections of arsenious acid (arsenious acid
I gramme, sodium carbonate i gramme, water 500 c.c.)- The mjec-
tions were given every two or three days. The initial dose was
15 minims (about i c.c), and the dose was rapidly increased to
40 minims (about 2-5 c.c.)- There was a distinct improvement in
the patients' condition, but it was only temporary, and the patients
eventually succumbed to the disease.]
[Greig and Gray^ followed up this line of treatment, but with
equally unsatisfactory ultimate results. Dutton, Todd, and Christy^
and Broden* likewise obtained temporary beneficial effects by means
of arsenic. Gray and Tiilloch* found that safe doses of arsenic had
little or no power to protect monkeys against an infection with
T. gambiense.]
[Attempts were next made to cure T. gambiense infections in
animals by the combined use of arsenic and trypanred. The experi-
ments of Laveran and of Thomas and Breinl on these lines have
already been alluded to (Section 3). A certain percentage of
recoveries resulted from this mode of treatment.]
[Gray and TuUoch tried the effect of ' tragarot ' in well-marked
cases of sleeping sickness, but although no ill effects were produced
(as often result from the administration of trypanred), no beneficial
effects could be observed in the patients so treated.]
[Other drugs or forms of treatment which have been suggested or
tried, but without permanent benefit, are chrysoidin (Balfour and
Neave^), 'brilliant green' (Wendelstadt and Fellmer^), thyroid
tabloids (Lorand'), and X rays (Mense'*).]
[ATOXYL. — The drug which has hitherto proved most useful in
the treatment of sleeping sickness in man and of T. gambiense infec-
tions in animals is atoxyl. As has been mentioned in Section i, it
was Wolferstan Thomas who first used atoxyl in the treatment of
the trypanosomiases, though Mesnil and Nicolle had independently
experimented with this drug before Thomas published his paper
in 1905.]
[Thomas warmly advocates the use of atoxyl in human trypano-
somiasis, and the encouraging results obtained with it in experi-
mentally infected animals by Thomas and Breinl, Laveran, Mesnil,
^ [Greig and Gray, Sleeping Sickness Commission Report, No. 6, 1905,
pp. 50-69.]
2 [Dutton, Todd, and Christy, Livetpool School of Tropical Medicine.
Memoir xiii.]
' [Broden, ' La Trypanosomiase chez I'Europeen,' Brussels, 1905.]
* [Gray and Tulloch, Sleeping Sickness Commission Report., No, 8, 1907.
PP- 30-53-]
^ [Balfour and Neave, Lancet, June 17, 1905 ; Second Report of the Wellcome
Research Laboratories, Khartoum, 1906, pp. 153-170.]
^ [Wendelstadt and Fellmer. See references given on p. 417.]
' [Lorand, German Congress of International Medicine, Deutsche med.
Wochenschr., v. i, 1905.]
* [Mense, Arch.f. Schiffs und Trop. Hyg., July, 1905.]
THE TREATMENT OF THE TRYPANOSOMIASES 435
and others (see Sections 3 and 4), and by Ayres Kopke/ Broden,^
Van Campenhout, Todd,^ Koch,* and others, in human trypano-
somiasis show that it is a vahiable remedy for this disease. Koch,
who has recently used it on a large scale in Uganda, speaks most
enthusiastically of it, and apparently regards it as a specific cure for
trypanosomiasis. Unfortunately, other observers have been unable
to corroborate Koch's statements. Kopke, Broden and Rodhain,
and others, have found that the administration of atoxyl causes a
great and rapid amelioration in the condition of the patients, but
that death eventually occurs in spite of the treatment. Kopke
quotes one case in which the treatment was continued for fifteen
months, the patient receiving in all thirty-three injections of atoxyl
(in doses of i to 1*5 grammes). Trypanosomes, nevertheless,
continued present in the cerebro-spinal fluid, and the patient died
after a series of epileptiform fits. J
[Van Campenhout advocates the combined administration of
atoxyl and large doses of strychnine sulphate. He recommends
giving the latter in small pills, each containing i milligramme
(^ grain). Three of these pills are given on the first day, and the
dose is increased by one pill a day until ten pills are taken per diem ;
then give eleven pills each day for a week, and gradually increase
the daily dose by one pill each week until fifteen (J grain) are taken
every day. After this the dose is gradually diminished. This treat-
ment gave very good results even when the patients (natives) had
reached the paralytic stage of the disease.]
[Thiroux and d'Anfreville^ treated a native of Portuguese Guinea,
aged about twelve to fourteen years, with three subcutaneous in-
jections of atoxyl (0"i5 gramme each) and one intraspinal injection
(o"02 gramme) ; strychnine was also given (dose from 3 increasing to
7 milligrammes). About a fortnight after the treatment was started,
and again a month later, trypanosomes could no longer be found in
the centrifuged cerebro-spinal fluid, and this fluid, as well as the
blood, was not infective on inoculation into monkeys. Two and a
half months after all treatment was stopped, the patient was appa-
rently well. It is remarkable that the patient improved so rapidly
after the small quantity of atoxyl injected. Possibly, as Laveran
suggests, trypanosomiasis is more easily curable in children (this
patient was only twelve or fourteen years old) than in adults.]
[All authorities are agreed that atoxyl is of considerable value in
the treatment of human trypanosomiasis. It is possible, moreover,
' [Ayres Kopke, ' Traitement de la Maladie du Sommeil,' Medicina contem-
poranea, Lisbon, 1907.]
^ [Broden and Rodhain, Arch. f. Schiffs u. Trap. Hyg., v. lo, 1906, p. 693.]
^ [Todd and Breinl, £rit. Med Journ., January 19, 1907 ; Todd and Kinghorn,
Lancet, February 2, 1907. A full bibliography is given in these two papers.]
* {Ko(^, Deutsche med. Wochenschr., Supplement to No. 51, igo6; abstract
m Brit. Med. Journ., January 19, 1907 ; also January 10, 1907, p. 49".]
^ [Thiroux and d'Anfreville. See in Laveran, Bull. Acad. Med., February 26,
1907.]
28—2
436 TRYPANOSOMES AND THE TRYPANOSOMIASES
that permanent cures may occasionally be effected by its administra-
tion, especially in the early stages of the disease. Nevertheless, we
must be very careful not to be misled by the immediate improvement
which usually follows its use, and to regard the improvement as
being evidence of a permanent cure. Atoxyl is undoubtedly an
advance on the older methods of treatment, but it is not a specific.
Finally, the very chronic course that human trypanosomiasis runs
(lasting often for several years) makes it necessary for us to follow up
the cases for years after treatment before we can confidently talk of a
permanent cure.]
[The Modr of Administration of Atoxyl in Human
Trypanosomiasis. — Atoxyl is usually given in subcutaneous injec-
tion, but it may also be administered by intramuscular, intravenous,
or intraspinal injections, or by the mouth. Broden and Rodhain
state that the drug is well borne by the stomach and intestines after
oral administration ; but most observers agree that atoxyl is decom-
posed by the acid gastric contents, and that signs of arsenical
poisoning are thus more easily produced.]
[In early trypanosomiasis, before the trypanosomes are found in
the cerebro-spinal fluid, intramuscular or subcutaneous injections
are sufficient ; but when signs of sleeping sickness have developed,
and trypanosomes are present in the spinal fluid, it is probably
advisable to inject the atoxyl into the spinal canal as well as into the
muscles or subcutaneously.^ Before injecting the drug, lo to 15 or
more c.c. of cerebro-spinal fluid should be withdrawn by lumbar
puncture. Correa Mendes,^ in Loanda, injected intraspinally 10 c.c.
of a I per 1,000 solution of atoxyl. Kopke, and Thiroux and
d'Anfreville have also used intraspinal injections.]
[The usual strength of the atoxyl solutions used for intramuscular
or subcutaneous injections is 10 per cent. Van Campenhout, how-
ever, prefers 5 per cent, solutions. Breinl and Todd recommend a
20 per cent, solution in sterile normal saline. The atoxyl separates
out on cooling ; but if the solution is warmed to blood-heat just
before use the drug completely redissolves, and there is no pain at
the site of injection.]
[The doses of atoxyl recommended by different authorities vary
considerably. Ayres Kopke has injected subcutaneously as much as
I and l"5 grammes of atoxyl into adult negroes without producing any
ill effects. Broden and Rodhain never gave more than o"8 gramme
for a dose. In two patients doses of o*6 and 0"8 gramme were
followed by toxic symptoms. Van Campenhout commences with a
' [In 1903 Nabarro and Greig injected a patient intraspinally and intravenously
with a solution of methylene blue, with the result that the trypanosomes dis-
appeared from the cerebro-spinal fluid. For intraspinal injections drugs must be
used in small doses ; otherwise there is a danger that they may combine with the
nerve elements and produce serious results.]
^ [Quoted by Kopke in communication made to the Society for Medical
Studies, Lisbon, December 29, igo6 : Medicina contemporanea, Lisbon, 1907.]
THE TREATMENT OF THE TRYPANOSOMIASES 437
dose of 0"2 to o"25 gramme of atoxyl, and increases it daily by
0'05 gramme until a dose of 0'8 gramme or more is reached. If
there are then no signs of poisoning, the daily dose remains at
this point for a fortnight or three weeks. It is then gradually
diminished by 0*05 gramme daily until the initial dose (o"2 gramme)
is reached, and the treatment is then interrupted for one or two
months. Three or more such courses of treatment are given as
required.!]
[Breinl and Todd recommend the following dosage : o'6 c.c. of a
20 per cent, solution of atoxyl (warmed) subcutaneously daily for four
days. On each of the four succeeding days o'8 c.c. is given, and the
dose is then raised to i c.c. each day. This dose is given daily for a
week, then on every other day for a fortnight, and afterwards twice
a week until all symptoms have disappeared and the patient's blood
is non-infective when inoculated into susceptible animals. After-
wards I c.c. should be given weekly for as long a period as possible. -
If toxic symptoms occur the same doses should be given, but less
frequently.]
[Certain precautions are necessary in the administration of atoxyl
by injections. Van Campenhout points out that the syringes and
needles used for the injections should be sterilized by boiling, since
carbolic acid decomposes atoxyl. It has also been found that
solutions of atoxyl decompose (with the liberation of free aniline)
and become yellowish if exposed to light. All solutions should,
therefore, be kept in dark (brown) bottles, and made up fresh every
week.]
[As has already been mentioned, the strong solution (20 per cent.)
of atoxyl recommended by Breinl and Todd should be warmed to
blood-heat before use. Atoxyl solutions must, however, not be over-
heated. Prolonged heating in the autoclave causes the solution to
decompose with liberation of aniline (Lanzenberg). Laveran has
found that solutions of atoxyl sterilized in the autoclave are at first
more toxic, and also more active against the trypanosomiases, than
solutions prepared in the cold. The initial increase of activity of
solutions sterilized in the autoclave rapidly diminishes, however, and
on this account the solutions used should always be recently prepared
and sterilized.]
[Toxic Symptoms. — When the initial dose is small and the
subsequent doses are gradually increased, there may be no toxic
symptoms. L. Martin states that a rise of temperature may often
follow the earlier injections of atoxyl. Schild,^ who first used atoxyl
^ [Quoted from Breinl and Todd's paper in Bri(. Med. Journ., January 19,
1907.]
^ [The disappearance of the auto-agglutination of the red corpuscles may be
of considerable help in deciding when it is safe to discontinue the atoxyl treat-
ment.]
^ [W. Schild, Berl. klin. Wochenschr., No. 13, 1902; Dertnatolog. Zeitschr.,
V. 10, Heft I.]
438 TRYPANOSOMES AND THE TRYPANOSOMIASES
therapeutically, describes the symptoms of poisoning as ' feelings of
chilliness, vertigo, headache, and tickling in the throat.' The
administration of atoxyl is never followed by albuminuria.]
[Broden and Rodhain observed severe abdominal cramps
radiating to the hypochondria, slowing of the heart, and marked
coldness of the extremities. Intestinal colic and diarrhoea were
absent in their patients.]
[Daniels states that ' burning on micturition, general dryness of
the mucous membranes and skin, with the formation of pruriginous
vesicles,' followed the administration of 0'2 gramme of atoxyl twice
weekly for fourteen months in one case. In another case vomiting
and diarrhoea occurred early in the course of treatment. When these
symptoms occurred the dose was reduced, and subsequently very
gradually increased.] i
[The action of atoxyl upon the trypanosomes is similar to that of
arsenious acid (Laveran, Thomas and Breinl). When a sufficiently
large dose of atoxyl is injected into an animal showing many trypanosomes
in its blood, the parasites are obviously diminished in number at the
end of four or five hours. Of those still present many are involuted
and degenerating : some are deformed, others spherical, movement is
diminished and the protoplasm granular. At the end of eighteen to
twenty-four hours the trypanosomes have entirely disappeared.]
[Finally, we may again refer to the opinion of Mesnil, Nicolle,
and Aubert that the alteriiate administration of the dye Ph and of
atoxyl may prove to be more valuable than atoxyl alone in the
treatment of human trypanosomiasis.]
^ [Quoted by Breinl and Todd in the article previously referred to.]
CHAPTER XIV
TRYPANOSOMES OF BIRDS
Section 1. — Historical Review and Geographical Distribution.
Until quite recently all that was known about the trypanosomes of
birds was contained in a paper by Danilewsky, published in Russian
in 1888, and summarized in French in iSSg.'^ This paper contains
numerous details about the appearance of the trypanosomes in fresh
blood, the changes they undergo, and their cultivation (?) in vitro.
Chalachnikov, in his ' Recherches sur les parasites du sang chez
las animaux a sang froid et a sang chaud ' (Charkov, 1888), devotes
a chapter to the trypanosomes of birds ; but he scarcely does more
than reproduce the descriptions given by his teacher, Danilewsky —
descriptions truly remarkable, seeing that they are based on observa-
tions made almost exclusively upon fresh blood.
In 1903 our knowledge was considerably increased by the re-
searches of Laveran ^ upon the Trypanosoma avium of an owl {Syrnium
aluco), of Dutton and Todd^ upon the trypanosomes of birds of the
genera Crithagra and Estrelda of Gambia, and of Hanna* upon the
trypanosomes of the pigeon and raven of India. These papers give
detailed accounts of the structure of the adult parasites, but say
nothing about their mode of reproduction.
According to Danilewsky, WedP was the iirst to see a trypano-
some in bird's blood, but his description is vague. The parasite
was 75 fj. to 150 ytt long, by 5 /^ to 6 /i wide ; with one end pointed, the
other blunt. It had a corkscrew-like movement. The host was
Loxia coccothraustes. Possibly this parasite was a Filaria.
In 1845 Gros,® after having discovered the flagellated parasites of
the blood of field-mice and moles, stated that he had found in the
blood of goat-suckers and cranes similar parasites, which measured
' Danilewsky, Biol. Centralb., 1885 ; Arch, slaves de Biol., 1886-1887 ; and
'Researches upon the Parasites of the Blood of Birds,' in Russian, Charkov, 1888 ;
French edition, Charkov, 1889.
2 Laveran, C. R. Soc. Biol., v. 55, May 2. 1903, p. 328.
^ Dutton and Todd, First Report of the Expedition to Senegambia, 1902, Liver-
pool, 1903, pp. 55, 56, pi. ii., figs. I, 2.
* Hanna, Quart. Journ. Micr. Sc, v. 47, December, 1903, pp. 437, 438, pi. 32,
° Wedl, Denkschr. Akad. Wien., v. i, 1850.
" Gros, Bull. Soc. Natur., Moscow, v. 18, 1845, p. 423.
439
440 TRYPANOSOMES AND THE TRYPANOSOMIASES
10 /x to 15 yu. in length and were very thin. His hsematozoon of the
raven, 100 /a to 130 fj, long and thinner than the small diameter of the
red corpuscles, he calls a trypanosome, but it is very doubtful if this
is the correct interpretation.
It appears quite certain that the T. eberthi Kent seen by Eberth
in the digestive tube of the fowl was not a trypanosome, but a Tricho-
monas, as was first suggested by Stein, and later by Leuckart.
The trypanosomes of Danilewsky have been found in several
Russian birds — the owl, the roller-bird (Coracias garula), and others.
Danilewsky saw trypanosomes in the blood of young roller-birds
only three or four days old. The parasites were numerous in the
blood in summer, but absent during the winter.
Ziemann, in Heligoland, found trypanosomes in the chaffinch
(Fringilla ccelebs)} but he did not describe the parasites. The same
observer states that he found, in a small white owl in Cameroon,
trypanosomes which showed male and female forms (?).^ [In a later
paper^ Ziemann mentions the occurrence of trypanosomes in the
kingfisher (Alcyon) in Cameroon.]
The owl in which a trypanosome was found by one of us was
bought in a Paris market. We have sought in vain for trypano-
somes in a large number of other French birds.
Of twenty-five birds examined at Bathurst, Gambia, belonging
for the most part to the genera Estrelda and Crithagra, Dutton and
Todd found only one {Estrelda estrelda) infected with the species of try-
panosome they call T. johnstoni. The other trypanosome described
by the same observers was common in the blood of the species of
Crithagra and Estrelda found at St. Louis on the Senegal (seven
birds infected out of fifteen examined) and at Bathurst.
Hanna, in India, found a small proportion of the domestic pigeons
infected with trypanosomes. He studied at the same time a trypano-
some of the Indian raven (sp. ?) in blood-films made by Ross in
i8g6. Donovan informs us that he has found trypanosomes in the
blood of Athene brama from the neighbourhood of Madras.
The brothers Sergent,* who examined the blood of a large number
of Algerian birds particularly in the environs of Algiers, found try-
panosomes in only three species : in one goldfinch {Fringilla car-
duelis) out of forty-six examined ; in two black-cap warblers {Sylvia
atricapilla) out of five examined ; and in three swallows out of ten
examined. The parasites were always so scanty that these observers
were never able to find them again in stained preparations.
Schaudinn,® in his inquiries into the alternation of generations
and the change of host of Trypanosoma and Spirochceta, used the
^ Ziemann, ' Ueber Malaria u. andere Blut parasiten,' Jena, 1898, p. 106.
^ Ziemann, ArcA. /. Schiffs u. Trap. Hyg., v. 6, 1902, p. 389. Probably he
saw sexual forms of Hcemamaba ziemanni.
^ [Ziemann, Centralb.f. Bakter., I, Orig., v. 38, 1905, p. 308.]
^ Ed. and Et. Sergent, C. R. Soc. Biol., v. 56, 1904, p. 132.
^ Schaudinn, Arb. a. d. kaiserl. Gesund., v. 20, 1904, p. 387.
TRYPANOSOMES OF BIRDS 441
Athene noctua of Rovigno, Istria, which contained trypanosonnes in
their blood (see Chapter III.)-
[Since 1903 our knowledge of the trypanosomes of birds has been
considerably increased by the investigations of Novy and McNeal,
Petrie, Thiroux, and others.]
[Thiroux^ has made an extended morphological and experimental
study of the trypanosome of the Java sparrow (padda, or rice-bird,
Padda oryzivora), discovered by Levaditi in 1904, and named by
Laveran and Mesnil T. paddcs. As will be mentioned later, Thiroux
succeeded in growing the trypanosome artificially on a modification
of Novy and McNeal's medium.]
[Novy and McNeal^ have published a long paper upon the
trypanosomes of birds. These observers examined 431 birds, repre-
senting forty species. It is a remarkable fact that the microscope
showed trypanosomes in only twenty-four out of 431 birds, whereas
the cultural method applied in only fifty-three cases gave twenty-nine
positive results {55 per cent.). By the two methods of examination
(microscopical and cultural), trypanosomes were found in thirty-eight
birds, representing fifteen species, as follows : Red-winged blackbird
{Agelaius phceniceus) , rusty blackbird {Scolephagus caroliniis), bluebird
{Sialia sialis), blue jay {Cyanocitta crislata), mourning dove {Zenaidura
macmira) , Ameucan goldfinch {Spinus tristis), flicker {Colaptus aurahis) ,
red-shouldered hawk {Bitteo lineatus), Baltimore oriole (Icterus gal-
bula), robin {Merula migratoria), English sparrow {Passer domesticus),
song sparrow [Melospiza fasciata), brown thrasher {Harporhynchus
rufus), hairy woodpecker {Dry abates villosus) , and house wren {Troglo-
dytes cedon).']
[Of the thirty-eight cases in which trypanosomes were dis-
covered, either microscopically or culturally, twenty-three showed
an infection with other parasites, such as Filaria, Hcemoproteus
majoris, H. danilewskyi, H. ziemanni, etc. Novy and McNeal state
that the study of the trypanosomes found in the blood, and also of
those, obtained by cultivation, shows that there are several distinct
species which exhibit no constant association with a given cytozoon.
Thus, the commonest species of trypanosome {T. avium) found in
the birds examined was associated with five different species of intra-
corpuscular parasites, or with Filaria, in addition to its very frequent
single occurrence. These observers add that ' under these circum-
stances it would indeed be difficult to estabish a relationship with
any of the intracellular organisms mentioned.']
[In addition to T. avium, which was found in twenty-five out of
the thirty-eight cases, several other species of trypanosome were
encountered. In four cases a variety (?) of T. avium was found ; in
each of two other cases trypanosomes which Novy and McNeal
^ [Thiroux, Ann. Inst. Past., v. 19, 1905, pp. 65-83.]
^ [Novy and McNeal, American Medicine, v. 8, November 26, 1904, pp. 932-
934 ; Journ. Infect. Dis., v. 2, March i, 1905, pp. 256-308. There are many excellent
photo-micrographs illustrating the latter paper.]
442 TRYPANOSOMES AND THE TRYPANOSOMIASES
regard as distinct species, to which they give the names T. laverani
and T. mesnili ; and in the remaining seven cases trypanosomes of
other species not yet sufficiently differentiated.]
[In April, 1905, VassaP discovered a trypanosome in the blood of
a pheasant (Polyplectrum germani), caught near Nhatrang, in Annam.
The bird was also heavily infected with intracorpuscular parasites.
Vassal suggests the provisional name T. polyplectri for this trypano-
some.]
[Petrie,^ at Elstree, in Hertfordshire, found trypanosomes in
several species of birds — house-martin {Chelidon urbica), song-thrush
(Turdus musicus), blackbird {Merula merula), swallow (Hirundo
rustica), chaffinch {Fringilla ccslebs), and yellow-hammer {Emheriza
citrinella). In every case the blood examination was negative, but
the trypanosomes were found in the bone marrow. In one case,
that of the house-martin, spirochaetes were present in the blood.
All the house-sparrows, starlings, crows, and jackdaws examined
were negative as regards trypanosomes.]
[In the Anglo-Egyptian Sudan, Sheffield Neave^ found trypano-
somes in the common vulture of Egypt {Neophron percnopterus) and
the red-breasted shrike {Laniarius cruentus). These trypanosomes
were very scanty in the birds' blood.]
[Wellman* has found a trypanosome in the blood of an African
dove (Treron calvd) in Portuguese Angola.]
[Sjobring^ states that trypanosome infection of birds is widespread
in the neighbourhood of Saftstraholm in Sodermannland, Sweden.
This observer found the parasite in nearly all passerine birds
examined by him, with the exception of Corvus and Pica. The
infection was apparently local, for it was not met with in other
districts. No details of morphology are given, but it is simply stated
that the forms observed resembled those of Danilewsky.]
[Donovan^ has recently described a trypanosome in the blood of
the Indian kite {Milvus govinda).^
[Lastly, trypanosomes have been found in several species of
South American birds. Aragao discovered them in Nicticorax
gardenia in Brazil (thirty-seven birds infected out of forty-seven
examined). Cerqueira^ found the same trypanosome in egrets ; it
appears to be identical with the T. avium minus of Danilewsky. In
one specimen of Tachyphormns ornata a different species of trypano-
some was found.]
1 [Vassal, C. R. Sar. Biol., June 17, 1905, v. 58, p. 1014.]
^ [Petrie,yoK'-«. Hyg., v. 5, 1905, pp. 191-200.]
^ [Neave, Second Report of the Wellcome Research Laboratory, Khartoum,
1906, p. ig8.]
* [Wellman,/<7ar«. Trop. Med., v. 8, 1905, p. 285.]
^ [Quoted from the paper by Novy and McNeal previously mentioned.]
" [See in Thiroux's paper, Ann. Inst. Past., v. 20, 1905, p. 79.]
'■ [Cerqueira, Thise de Rio de Janeiro, 1906; abstract by Marchoux in Bull.
Inst. Past., V. 4, p. 1041.]
TRYPANOSOMES OF BIRDS
443
Section 2. — Morphology and Cultivation of the Trypanosomes
of Birds.
The trypanosomes of the owl and roller-bird, studied by Darii-
lewsky,^ appear as fusiform parasites (Fig. 59), with a tapering or even
sharply-pointed posterior extremity which varies in length. The
anterior extremity gradually tapers off, and is prolonged into a wavy
flagellum of variable length, which gradually diminishes in thickness,
so that at last it becomes a scarcely visible filament. The flagellum
is closely connected with the undulating membrane, which appears
in the form of a hyaline, unstained border, more or less narrow,
extending from the flagellum to the posterior extremity. The
intimate relation between the flagellum and undulating membrane
Fig. 59. — Trypanosomes of Birds. (After Danilewsky.)
1-3. Different adult forms. Between 2 and 3 is a red corpuscle of the bird, to give an
idea of the relative sizes of the trypanosomes and red corpuscles. 4-7. Stages in
the binary division of a trypanosome.
is plainly seen on watching the movements of the parasite, and
Danilewsky draws particular attention to this point.
Danilewsky figures the vesicular nucleus, which he says he saw
very distinctly in the living state. The forms showing striations
(Fig. 59, 2), which resemble the parasites seen in the Batrachia, are
rare. From the point of view of size the trypanosomes seen in the
blood may be divided into two groups : one consisting of stumpy
forms with a long flagellum, measuring 18 /x to 22 /^ in length, not
including the flagellum ; the other of long forms 45 /« to 60 /a in length ;
but transition forms also occur. In all the parasites the width is
from 7 /x to 8 /i.
Even in young roller-birds three or four days old the parasites
are specially numerous in the red marrow of the bones, where many
different forms are seen. ' In many cases,' says Danilewsky, ' when
I found only one or two trypanosomes after a long search in the
heart blood, I found many in the red marrow of the bones.' There
are cases7 however, in which the blood contains many more parasites
than the bone marrow.
^ Danilewsky has confused in the same description, and under one name —
T. avium — the trypanosomes of the owl and roller-bird, although they were
probably different species.
444 TRYPANOSOMES AND THE TRYPANOSOMIASES
Danilewsky describes in detail the longitudinal division of the
parasite. According to his figures, which are reproduced here
(Fig. 59, ^ to 7), the process is analogous to the unequal division of
T. lewisi ; one of the two trypanosomes retains the original undu-
lating membrane and flagellum, while a new flagellum develops in
the other parasite. Often before the two daughter trypanosomes
separate, the one with the new flagellum starts dividing again.
All these changes were studied by Danilewsky under the micro-
scope, either in hanging-drop or in ordinary fresh preparations. The
division of a trypanosome into two usually takes from twenty to
thirty minutes, or at the most an hour. It is, however, still a little
doubtful whether this is the normal mode of reproduction of the
trypanosome in circulating blood.
Danilewsky also describes reproduction by a process of segmenta-
tion, which he observed in blood kept for six to eight days at 22° C.
in sterilized pipettes. A large spherical form, without trace of a
flagellum, divides into two, then into four, and so on. A ' morular '
mass is thus produced, containing thirty - two elements, which
elongate, then become fusiform, and finally become transformed into
an equal number of trypanosomes, with a fairly long flagellum, but
no undulating membrane. It is to these forms that Danilewsky gave
the name Trypanomonas. Knowing what we do now about the culti-
vation of trypanosomes, it is probable that these masses of Trypano-
monas were really cultivation forms. It is much more diflicult to
admit that they were derived from the ' morular ' masses, as Dani-
lewsky thinks.
Trypanosoma avium, Danilewsky, Laveran emend. — 'One of us
{loc. cit.) has given the following description of the trypanosome of
Syrnium aluco :
' In fresh blood the trypanosome of the owl appears as a very
active worm-like body, with an undulating membrane and an anterior
flagellum.
' In blood dried, fixed, and stained by my ordinary method
(silver oxide-blue, eosin, and tannin), I obtained excellent prepara-
tions of the trypanosomes (see Fig. 60 and Fig. 10 in the coloured
plate). The trypanosome is fusiform ; the protoplasm stains so
darkly that the nucleus and centrosome are often scarcely visible ;
the anterior extremity tapers off and terminates in a flagellum ; the
posterior extremity is drawn out to a variable extent. About the
middle of the parasite is an oval nucleus (/, «). The centrosome is
spherical and fairly large (/, c), and when the posterior end is very
pointed, the centrosome is situated a considerable distance from the
tip. The undulating membrane is well developed and bordered by
the flagellum, which joins the centrosome. Below the wavy flagellum
a parallel line or striation is often seen, and this appears to be due
to a fold in the membrane. These lines are seen in Fig. 60, /, at
the prominent parts of the undulating membrane.
TRYPANOSVMES OF BIRDS
445
' The trypanpsome is from 33 /u. to 45 /jl in length, including the
flagellum.
' In one case (Fig. 60, 2) the centrosome had divided, which may
certainly be looked upon as the beginning of a dividing stage. This
is in agreement with the observations of Danilewsky, who saw only
one mode of multiplication — namely, longitudinal division — in the
trypanosomes of birds.
'The trypanosomes were scanty in the blood of the owl, and they
were not more numerous in the kidneys than in the peripheral blood.
' From the above description of the parasite it is evident that the
tr5'panosome of the owl should be included in the genus Trypanosoma.
It is highly probable that it is the same parasite as that seen by
Danilewsky in an owl, and called by him Trypanosoma avium. I
think that this name should be adopted for the trypanosome of the
11. Nucleus, c. Centrosome.
Trypanosoma avium.
m, )«'. Undulating membrane. /. Flagellum. In .? the
centrosome has divided.
owl, and that it be left an open question whether the trypanosome of
the roller-bird belongs to the same species or not.'
It is doubtless an allied species which Schaudinn observed in
Athene noctua (see Chapter III.).
Trypanosoma johnstoni, Dutton and Todd, 1903. — Found in the
blood of Estrelda estrelda in Bathurst.
The following description of the parasite and Fig. 61, i, are taken
from the authors' paper :
' Only two to four parasites were seen in a coverslip preparation.
In fresh preparations the parasite appears as a very actively moving
spirillum-like body ; so striking, indeed, is this resemblance, that at
first sight it was thought to be a true spirillum. The undulating
membrane is scarcely recognisable, and the parasite has no free
ilagellum. When its movements have become slower, the organism
is seen to possess a long straight body, pointed at both ends. At a
point about one-third of its length distant from the posterior end of
44& TRYPANOSOMES AND THE TRYPANOSOMIASES
the parasite is seen a refractile spot, the centrosome. A little further
on a slightly refractile area indicates the position of the nucleus. . . .
'In stained preparations (see Fig. 6i, /) the above details are
better seen. Along the free border of the undulating membrane
runs the flagellum, stopping abruptly at the anterior end of the'
organism in a small red dot. The nucleus is elongated, granular,
and does not quite extend across the short axis of the parasite. The
centrosome is a small dot or oval spot of chromatin surrounded by a
small halo. The protoplasm takes on a uniform blue colour.
' The length of the parasite is from 36 ju to 38 fi, and its width at
the nucleus 1-4 /^ to i-6 m. The distance from the centrosome to the
Fig. 61. — Other Bird Trypanosomes.
I. T. johnstoni. 2. Another Gambian trypanosome. 3. Trypanosome of the Indian
pigeon. 4. Trypanosome of the Indian raven, n. Nucleus, c. Centrosome,
a. Anterior chromatic granule. /. Flagellum. Magnif. 1,000 diams. (i and 2
after Button and Todd ; 3 and 4 after Hanna.)
posterior end is 10*4 /x. Distance from the centrosome to the centre
of the nucleus is g /^ to 10 fj,.
' No developmental or dividing forms were seen in any prepara-
tion. Two larks were inoculated, each with 0'5 c.c. blood from this
bird, but unsuccessfully.'
Another Gambian Trypanosome — Trypanosome of the
Pigeon and Raven of India. — These trypanosomes, instead of
being very thin and elongated, like T. johnstoni, are short and
stumpy, and have a free flagellum (see Fig. 61, 2 to 4).
[The table on the opposite page,^ based upon those of the authors
and of Thiroux, gives the most important dimensions of these three
trypanosomes, as well as of several of the other bird trypanosomes
hitherto described.
1 [It must not be inferred that all the trypanosomes mentioned in this table are
regarded as distinct species.]
TRYPANOSOMES OF BIRDS
447
^
^
^ .
'u^
■a
c
i.
a
s
(a
1
•..2
•^
If
■ii
a-o
s-s
« a
?i>
■S-o
X"^
cn
COM
|2
§s
eS
ss
§1
IS
Q
°g
S
•5 «
ow
f-i
•oS
H
1
■o.S
.a ,
H5
1
,^1
>
Is
IE
Total length
33 to
36 to
32'5fi
45 to
40 to
50 (»
30 to
46 M
28 n
58 to
28 (»
20 ^'*
50 M*
18 to
.35'°
45 >i
38 /A
60 fJL
56,1
40 /x
60 fi
25 ^«
Ss*'*
Width at
3f^
I '4 to
8f*
6 to
3 to
3 to
5 to
5^
9»'
4 to
3f
6^
8/x
4 to
4 to
level of
(abt.)
i"6 ju.
8^
4-8^
3'S(i
7^
5M
611
6-5 f*
nucleus
Distance of
3 to
10-4^
2(i
19 to
8 to
5M-
TO jU.
10 fj.
4(i
7 f
4»»
I f
7M-
o"5 to
13 to
centrosome
Sf
(abt.)
22 jU
9'5 11
6fi
25 A'
from pos-
terior end
Distance of
II 11
9 to
9-6^
4 to
—
12 fi
9 to
12 fj.
—
—
—
10 JU.
6'5 to
6-5 to
centrosome
10 jU
6-5^
10 jU.
■12 (1
10 fi
from centre
of nucleus
Distance of
17 to
26 JU.
20 fi
29 to
32 to
27^
23 M-
24 JU
—
—
—
—
—
13 to
25 to
centrosome
20 jH
36-3 H
46-5^
23 11
45 1^
from an-
terior end
Free flagel- ii fi
10 to
6-8 11.
6-8 (i
16 /Lt
I "5 to
12 jU.
8^
10 11
10 JU
(?)
P)
6 to
10 to
lum (abt.)
12 fi
6JLL
13 M
20 ju
■ These dimensions are the length of the body without free ilagellum. In the case of T. Ictverani and T, mesnill
the free flagellum was not stained, but Novy and McNeal think one was present.
In the two Indian species, especially that of the pigeon, the
posterior end is drawn out to a very fine point. Although these
trypanosomes are of about the same length, they differ markedly in
two respects : (i) the parasite of the raven is half as wide as that of
the pigeon, and (2) the centrosome of the former is only half as far
from the posterior end as it is in the latter. A more detailed com-
parison between these two species is not possible, since Ross's pre-
parations of the raven's blood in which Hanna studied the parasite
have faded.
The trypanosome of the pigeon (Fig. 61, j) has a very small
centrosome, situated in the centre of a clear vacuole; a well-defined
undulating membrane, with a short free flagellum ; and a thin ribbon-
like nucleus, extending across the width of the body. In the homo-
geneous or longitudinally striated cytoplasm there are several
chromatic granules, which are particularly numerous near the
posterior end.
The parasites were always relatively scanty in the blood of the
pigeons, and Hanna did not observe any dividing forms.
The parasite of the small birds (gen. Estrelda and Crithalda) of
St. Louis and Bathurst (Fig. 61, 2) differs from the foregoing in its
very blunt posterior end and in the terminal position of the centro-
some. The body stains a deep blue, and shows an appearance of
longitudinal striation. The nucleus is large and elongated trans-
versely, and its chromatin stains diffusely. The relatively large
centrosome is in the centre of an unstained vacuole. The free
flagellum is much longer than in the foregoing species. Button and
Todd did not see any developmental or dividing forms. Two pigeons
and two larks were inoculated without success.
448 TRYPANOSOMES AND THE TRYPANOSOMIASES
Trypanosoma paddje, Laveran and Mesnil. — In May, 1904,
Dr. Levaditi discovered, in the blood of a Java sparrow (Padda
oryzivora) bought in a shop in Paris, a trypanosome for which we
propose the name T. paddce. Dr. Levaditi kindly gave us the in-
fected bird, which enabled us to study this new trypanosome.
The Padda oryzivora is very often infected with an intracorpuscular
hasmatozoon, Hcemamceba danilewskyi,^ but the occurrence of trypano-
somes in the blood of these birds must be very rare. One of us had
examined a large number of them, but had never before seen trypano-
somes in their blood.
T. paddce is 30 /^ to 40 /it long, by 5 /x to 7 /^ wide. These measure-
ments vary a little, because the parasite is constantly contracting
and elongating.
The body of the parasite is fusiform, bulging more or less
towards the middle. The anterior end, which is always very
attenuated, accompanies the flagellum almost to its tip. The pos-
terior end, which varies a little in shape, is usually very sharply
pointed.^ There are fine longitudinal striations on the surface of
the body. In the protoplasm fine granules are seen, in addition to
the nucleus and centrosome. In front of and behind the nucleus
clear spaces, which are quite as large as the nucleus itself, can
be made out in lightly stained preparations. The nucleus is
situated about the centre of the body, and stains only moderately
well by our ordinary method. The centrosome is large and rounded,
and stains a deep violet. It is situated a variable distance from the
posterior end, according to the state of contraction or elongation of
this extremitj' ; but it is sometimes nearer the nucleus, especially in
forms about to divide. The undulating membrane is narrow and
much indented, and is so thin that it remains uncoloured, even in
the most carefully stained preparations. The free and attached
parts of the flagellum are thin.
[Thiroux, from whose paper^ the following additional facts con-
cerning T. paddce are taken, states that the nucleus, flagellum, and
undulating membrane stain feebly by the ordinary methods, but
that better results are obtained by staining at a temperature of 53°
to54°C.]
[Multiplication forms are seen only in birds that are heavily
infected. Equal binary longitudinal fission is the usual mode of
reproduction, but sometimes unequal fission is observed. At first
the centrosome enlarges and becomes fusiform, and simultaneously
the adjacent base of the flagellum broadens out. Then the flagellum
begins to split, and at the same time the centrosome and nucleus
segment, and lastly the protoplasm divides.]
1 Laveran, Soc. de Biol., April 30, l8g8, and January 13, 1900.
^ The posterior end is sometimes as pointed as the anterior, so that in badly
stained preparations in which the flagellum is not visible, one might think that
there was a flagellum at each end of the parasite.
^ [Thiroux, Ann. Inst. Past., v. 19, February, 1905, pp. 65-83.]
TRYPANOSOMES OF BIRDS 449
[Agglutination of Trypanosoma paddce. — Agglutination rosettes,
similar to those seen in the case of T. lewisi, may be produced by
adding a drop of blood from a bird which has recovered from the
infection, or in which the infection is of long standing, to the blood
of a bird rich in parasites. The serum of normal birds does not
agglutinate. As with T. lewisi, the trypanosomes are joined by
their posterior ends, the flagella remaining free and active at the
periphery of the rosettes. Auto-agglutination is often seen in birds
whose blood contains very many parasites, and it appears that in
such cases the parasites diminish in number more quickly than when
auto-agglutination is absent.]
[T. paddcB dies in thirty hours in blood mixed with i per cent,
citrate at o°, 22°, or 35° C, but remains alive in cultures for a long
time.]
[Cultivation of Trypanosoma paddce. — Thiroux succeeded in
growing this trypanosome artificially on a modification of Novy and
McNeal's medium.]
[The medium was blood-agar containing 30 grammes of agar per litre,
and an equal volume, or one and a half times its volume, of defibrinated
goose blood. Pigeon blood was found not to answer. The water of con-
'densation was inoculated with the heart blood of a padda containing
trypanosomes. At 37° C. the trypanosomes begin to multiply in the
water of condensation in eight or nine days, and reach their maximum
development in twelve to fifteen days. Involution forms then appear in
the culture, but the trypanosomes remain motile for more than forty days.
Successive subcultures on blood agar were also made, and these showed
very active reproduction of the trypanosomes.]
[In young cultures the trypanosomes are fusiform, more or less
granular parasites, with a flagellum at the anterior end, but without any
trace of an undulating membrane. They vary in length from 12 ;n to 30 /x
and in width from i'5 ju. to 5 /u. The larger forms often have two flagella.
In cultures fifteen or more days old numerous involution forms are seen in
addition to the Herpetomonas-l\ke parasites. These involution forms assume
all stages from a fusiform to a spherical shape. In very old cultures , the
spherical, and occasionally also the fusiform, parasites present a morular
appearance, due to the segmentation of the protoplasm. Thiroux suggests
that this may represent the beginning of an encysted condition and the
appearance of ' resistant spores.' This idea is apparently confirmed by
the fact that the Herpetomonas, which are closely allied to the trypanosomes,
particularly in their culture forms, have analogous resisting forms.^]
[The parasites are not easily stained in liquid cultures, but satisfactory
results can be obtained by fixing thin films in absolute alcohol and staining
by the eosin-Borrel-blue tannin method. The fusiform parasites have the
nucleus near the anterior end of the body, while the centrosome, with the
attached flagellum, is between the nucleus and the anterior end. This
gives the parasites an appearance like that of Herpetomonas rather than of
trypanosomes. These cultural forms are similar to those of the Leishman-
Donovan bodies. The amoeboid involution forms seen in very old cultures
are often devoid of a nucleus, but contain large chromatic granules.]
[Agglutination may be produced in cultures of T. padda by adding
a drop of blood from a bird that has recovered from the infection or that
1 [Prowazek, Arb. a. d. kaiserl. Gesund., v. 20, part iii., 1904, p. 440.]
29
450 TRYPANOSOMES AND THE TRYPANOSOMIASES
has been infected for a considerable time and has very few parasites in its
blood. The blood of healthy birds has no such effect. Rosettes form in
from five to fifteen minutes, and all the parasites have their fiagella directed
towards the periphery.]
[Auto-agglutination is seen in cultures, as it is in the blood of birds that
are severely infected.]
[Inoculation Experiments. — This was the first trypanosome
of birds to be successfully inoculated into animals (1904). Since
Thiroux's experiments, Novy and McNeal have succeeded in inocu-
lating a canary with T. avium.l
[Paddas. — Thiroux was able to transmit the infection from one
padda to another by means of subcutaneous, intramuscular, intra-
venous, or intraperitoneal injections of infective blood. Intraperi-
toneal inoculation was the most reliable method, the incubation
period varying from twelve hours to eighteen days. After sub-
cutaneous injection the incubation period was never less than twelve
days. The infection produced varied considerably in severity. In
some cases it was very slight, and only an occasional parasite was
found in blood - films ; in other cases the parasites were very
numerous — sometimes even equalling the red blood -corpuscles in
numbers — and in such cases the birds usually died of the infection.
In an average case, of moderate severity, after a variable incubation
period, which, however, was usually short, the parasites increased
progressively in number for nine to fifteen days and then diminished,
the infection remaining stationary sometimes for more than forty
days. Ultimately the parasites very gradually disappeared, and the
infection sometimes remained latent for two or three months,
trypanosomes being only very rarely seen in the blood. The long
duration of this latent phase makes it impossible to study the im-
munity produced by an attack, for one can never be certain that a
bird is really cured.]
[After a severe infection of long duration the spleen is often
enlarged considerably. Many parasites are present in the spleen
and bone marrow, but apparently not more than were present in the
blood during life.]
[Thiroux found all paddas more or less susceptible to intra-
peritoneal inoculation with this trypanosome.]
[Intraperitoneal injections of cultures of T. paddcs also gave rise to
infection. The incubation period varied from fourteen to eighteen
days, and the infection was always mild. Very few parasites were
found in the blood, and they did not differ in appearance from those
seen in paddas which were infected directly with blood.]
[Other Birds. — The following species of birds were also found
susceptible on intraperitoneal inoculation : Serinus meridionalis,
S. canarius, Lagonostida minima, Mariposa phcenicatis, and Estrelda
cinerea. The following birds were found insusceptible: Geese,
pigeons, Fringilla ccelehs, Passer domesticus, Emberiza, citrinella, and
TRYPANOSOMES OF BIRDS 451
Pytelia subflava. It is- interesting to note that, although the goose is
refractory to inoculation, T. paddcB is able to grow artificially on
media containing goose blood.]
[It follows from Thiroux's observations that one species of
trypanosome can infect several species of birds ; also that one
species of bird may be susceptible to different trypanosomes. Thus,
the canary, which is susceptible to T.paddce, is, according to Novy
and McNeal, equally susceptible to T. avium. Also T. paddce may be
inoculated into birds of the genus Estrelda, which Button and Todd
found to be naturally infected with T. johnstonii]
[The rat, mouse, and frog were found to be refractory on
inoculation.]
[Levaditii and Sevin^ have studied the action of normal serums on
T. padda. They found that the serum of a normal guinea-pig (which is
refractory to T . padda) agglutinates only slightly, but that the same serum
heated to 56° C. agglutinates well. The explanation seems to be that
normal guinea-pig serum contains a thermo-labile anti-agglutinin. If a
trace of fresh guinea-pig serum is added to the heated serum agglutina-
tion is prevented.]
[The serum of the rat, which is also refractory to T. padda, can
immobilize and disintegrate this trypanosome. Under these conditions the
trypanosome becomes spherical and vacuolated, and shows only a vestige
of flagellum and undulating membrane. This trypanolytic property of rat
serum disappears when the serum is heated to 56° C. It cannot be
restored by adding the fresh serum of another species of animal. Sevin
has found that this heated serum favours the trypanolytic action of the
same serum unheated.]
[According to Levaditi and Sevin, animals which are normally resistant
to T.paddce may be divided into two groups : (i) Those whose serum is
not agglutinating or paralyzing, as, for instance, mice ; and (2) those whose
serum has a trypanolytic action, as, for example, white rats. In gronp (i)
the trypanosomes injected intraperitoneally at first show signs of multipli-
cation by fission, and later on become, while still living, the prey of the
phagocytes. In group (2) the trypanosomes injected are rapidly destroyed
and show no signs of multiplication.]
[NoVY AND McNeAL'S OBSERVATIONS ON THE TRYPANOSOMES OF
Birds. — As has already been stated, these investigators have found
that trypanosome infections of birds are very common and wide-
spread. The methods they used included the direct detection of
trypanosomes in the blood, cultivation, and the inoculation of birds
with pure cultures. The detection of trypanosomes in fresh blood-
films was not easy, owing to the extreme scarcity of the parasites ;
yet this method was, as a rule, more delicate than the examination of
stained films. Nocht's modification of Romanowsky's stain was
used. It was found, however, that these bird trypanosomes did not
stain so well as T. lewisi or T. brucei, for it was the exception to find
^ [Levaditi and Sevin, C. H. Soc. Biol., v. 58, J905, pp. 694-697.]
2 [Sevin, ibid., v. 59, 1905, pp. 122, 123; abstracts in Bull. Inst. Past., v. 3,
pp. 578, 804.]
29 — 2
452 TRYPANOSOMES AND THE TRYPANOSOMIASES
specimens with well-stained nucleus and flagellum. Even when no
free flagella could be seen in stained specimens, they could be seen
in fresh blood-films.]
[The cultivation method proved to be far superior to direct
examination, inasmuch as it rendered possible the isolation of the
trypanosomes when apparently none could be detected by the micro-
scope. In cultivating the trypanosomes it is a mistake to have the
meat - extract too concentrated. This is particularly true of the
initial or first generation.]
[The best formula is the following: The extractives of 125 grammes
of rabbit or beef meat in i litre of distilled water, 2 per cent. Witte's
peptone, 0-5 per cent, salt, 2 per cent, agar, and 10 c.c. of normal sodium
carbonate solution. The agar thus prepared is filled into tubes, and
sterilized in the autoclave at 110° C. for thirty minutes. When cooled to
about 50° C, 2 volumes of defibrinated rabbit's blood are added, and the
mixture is then allowed to solidify in an inclined position. When firmly
set it is placed upright for a few minutes until a few drops of water of
condensation appear. This liquid is then inoculated with a drop of blood
taken from the heart of the bird by means of a fine pipette.]
[The cultures of the bird trypanosomes usually develop very
quickly at 25° C. As a rule, growing trypanosomes can be recog-
nised on the third day. On the sixth or seventh day they are
usually extremely abundant and very actively motile. After this
they diminish in number, and involution forms appear. Sometimes
colonies are formed on the agar above the water of condensation.
Subcultures succeed well as a rule. By means of the cultural
characteristics it is possible to differentiate the bird trypanosomes
from one another, as well as from the mammalian trypanosomes
(T. lewisi, T. brucei, and T. evansi).'\
[Novy and McNeal consider that they have investigated at least
four distinct species. The one most frequently met with (in twenty-
five out of thirty-eight birds infected) they identify with Danilewsky's
T. avium. Two types of this trypanosome were found in the blood,
corresponding closely to the majus and minus of Danilewsky. These
two types belong to the same species, and always give rise to the
same cultural forms. Novy and McNeal regard the large form as
a multiplication, or possibly sexual, type of the smaller and more
common form.]
[The large form varies considerably in length : body 35 /u to 65 fj,,
free flagellum 15 /li to 20 /ti. The width is 5 ju. to 7 /a. The centrosome
lies close to the nucleus and is in a large clear space. The nucleus
stains badly. Six or eight well-marked strise or myonemes are
present along the entire length of the body. The posterior end is
long and tapering. In the living condition the contortions of the
parasite are very active, but there is little tendency to travel out of
the field of the microscope.]
[The small form is the most common one met with in the blood
TRYPANOSOMES OF BIRDS 453
of birds. The total length, flagellum included, is about 25 /* to 30 ^,
the body proper being about 20 fju long. The width ranges from
3'5 /"■ to 5 /i. In some parasites the centrosome appears to be at the
very tip, in others it is 4 /i or 5 /i distant. Novy and McNeal suggest
that the larger of the small forms, with its centrosome at a distance
from the tip, constitutes a transition to the large form, which has its
centrosome close to the nucleus.]
[This smaller variety is thought to be identical with Laveran's
T. avium found in the owl (see p. 444), and also with the short, broad
trypanosome found by Button and Todd in Senegambia. Hanna's
Indian bird trypanosomes Novy and McNeal identify with their large
form of T. avium. T. johnstoni (Dutton and Todd) they regard as a
distinct species ; and T. paddce they regard as being culturally
distinct from T. avium, and as closely resembling T. laverani.^
[Cultural Characteristics of Trypanosoma avium. — Two
types of parasite are seen in cultures : (i) Round, oval, or spindle-
shaped cells, with the centrosome by the side of, or anterior to, the
nucleus. These are arranged in rosettes — simple or primary and-
multiple rosettes — in which the flagella are directed centrally, as in
the culture or ' multiplication ' rosettes of T. lewisi ; and (2) extremely
slender, long, wavy, darting forms — the spirochaetiform parasites of
Schaudinn. These ' spirochastes ' have a well developed undulating
membrane, the centrosome lying in the posterior part of the body.
They are often joined by their posterior ends, the flagella being
directed peripherally (' agglutination rosettes '). It might be sup-
posed, say Novy and McNeal, that the rosette and spirochsete forms
represent two distinct species ; but on various grounds (the two
forms were met with in every one of the eighteen strains examined,
etc.) they are of opinion that the two forms belong to one
species.]
[Injections of these cultures into birds were not very satisfactory.
Only one canary out of many birds (canaries, robins, sparrows, etc.)
injected became infected.]
[Trypanosoma mesnili, Novy and McNeal, 1905. — This try-
panosome was met with in the blood of a hawk {Buteo lineatus).
It differs morphologically from T. avium, and an even greater
difference can be seen in cultures. This trypanosome is character-
ized by its large size, and by a wide, rounded posterior extremity.
Its dimensions are given in the table on p. 447. The cytoplasm
stains deeply and is coarsely granular.]
[Cultures grpw very rapidly and show two types of cells, re-
sembhng in a general way those met with in T. lewisi and T. avium :
(i) Small cells, 10 /x to 12 /*, even 15 jj., long, by 4 /i to 6 /* or 7 /* wide.
The rapidly growing cells are much smaller, and have a very short free
flagellum ; the fully developed cells have a free flagellum about as
long as the body. These cells form the multiplication rosettes.
(2) Large cells, 20 /* to 25 /* long, by 4 /* to 6 /* wide ; free flagellum,
454 TRYPANOSOMES AND THE TRYPANOSOMIASES
17 jtt to 20 /*. These correspond to the spirochaete stage of T. avium,
but they are shorter and wider, and have a very long free flagellum.
These cells form the typical agglomeration rosettes, with the flagella
directed peripherally.]
[Injections of these cultures were made into an owl and three
chickens, but unsuccessfully.]
[Trypanosoma laverani, Novy and McNeal, 1905. — This try-
panosome was met with in the blood of a goldfinch {Spinus tristis).
In size it agrees with the smaller variety of T. avium (see table on
p. 447). The posterior end is very pointed; the posterior part of
the cell is coarsely granular.]
[In artificial culture growth is very slow and scanty. The
rosettes are smaller and less numerous than in T. avium and
T. mesnili. The characteristic feature of this trypanosome is the
presence of a terminal rod, which usually lies against the wall at
the posterior end of the cell. This rod is best seen when division is
about to occur. Many free forms are seen in cultures. They are
either typical spindle-shaped cells, 14 /* to 20 /^ long, by 4 /* to 5 /x in
greatest width, with a long free flagellum ; or slender cells, 20 /* to
25 /i long, by 2"5 /* to 3 /* wide, and with a shorter free flagellum.]
[Trypanosoma sp. (?). — This trypanosome was obtained twice
from blue jays and once from a rusty blackbird. It was got only
by cultivation, and although Novy and McNeal feel sure it is a
distinct species, they have not yet named it. Growth is rapid ;
rosettes are very scarce, the free forms predominating. These are
wide, actively motile cells, about 15 /«• long, by 3 /«. or less in
width.]
[Relation of Trypanosomes to other Blood Parasites. — Many of the
birds inoculated by Thiroux with T. paddce had a double infection —
with the trypanosome and Halteridium. From his experiments upon
paddas and canaries Thiroux has come to the conclusion that
T. paddcB and H. danilewskyi have no relation to one another, that
their respective life cycles are quite distinct, and that the birds are
really suffering from a double infection. Novy and McNeal have
come to the same conclusion with regard to T. avium, and the various
intracorpuscular hsematozoa met with by them in birds. Reference
has already been made (see p. 45) to their interpretation of Schau-
dinn's observations. They maintain that T. noctuce and Spirochxta
ziemanni of Schaudinn probably represent trypanosomes which have
multiplied in the mosquito ; they are not to be considered as stages
in the life-history of cytozoa. The facts that the same species of
bird may be infected by several species of trypanosomes ; that the
trypanosomes may or may not be associated with intracorpuscular
parasites ; that no constancy can be shown to exist between a given
trypanosome and a given cytozoon ; and, lastly, that birds infected
only with cytozoa do not give rise to cultures of trypanosomes, even
when many mature gametes are present, have led Novy and McNeal
TRYPANOSOMES OF BIRDS 455
to conclude that the simultaneous presence of trypanosomes and
other blood parasites is to be regarded as an accidental coincident
infection, and that there is no genetic relation between the
parasites.]
. [Trypanosoma polyplectri. Vassal, 1905. — -The dimensions of
this trypanosome are given in the table on p. 447. In the fresh con-
dition it is very active, but does not move much from place to place.
It has a long, pointed posterior extremity, and sometimes there are
granules between the centrosome and the posterior end of the body.
Multiplication takes place by simple binary fission. As has already
been mentioned (p. 442), this trypanosome was found by Vassal near
Nhatrang, Annam, in a pheasant, which was severely infected with
intracorpuscular haematozoa. Vassal has given it the provisional
name T. polyplectri, but he adds that in the light of Novy and
McNeal's observations it is wise to keep an open mind upon its
specific individuality until a more complete study of it has been
made.]
[Trypanosomes of Birds in the Anglo-Egyptian Sudan.
— Neave found trypanosomes in several vultures and in a red-
breasted shrike. The dimensions of these parasites are given in the
table on p. 447. The trypanosomes found in the blood of vultures
were about as large as the large form of T. avium described by Novy
and McNeal. The posterior end was very pointed, and was appa-
rently prolonged into a flagellum 4 ^u. to 6 /ti long.]
[The trypanosome of the shrike was considerably shorter than
that of the vulture (see p. 4^7). Its centrosome was rod-shaped,
and Neave states that he is unable to identify this trypanosome with
any previously described species.]
[Trypanosome of the African Dove (Wellman). — This try-
panosome is short and stumpy. The nucleus lies with its long axis
(longest diameter about 6 yu) across the width of the body. Faint
longitudinal strise or myonemes are present. The cytoplasm con-
tains fine granules. The dimensions of the parasite are given on
p. 447.]
[Trypanosome of Nicticorax. — This trypanosome, discovered by
Aragao in Nicticorax gardenia in Brazil, has been further studied by
Cerqueira, It appears to be identical with T. avium minus of
Danilewsky, and belongs to the type lewisi. Cerqueira found that it
grew well in Novy and McNeal's medium in three days. Three
types of multiplication forms are described : (i) ordinary trypano-
some forms ; (2) Spiroch(sta-\ike forms ; and (3) large and small
spherical forms.]
[Attempts at artificial infection gave negative results.]
To sum up, the trypanosomes of birds known up to the present
belong to three diiferent types :
I. Trypanosomes of the type lewisi of rats ;
456 TRYPANOSOMES AND THE TRYPANOSOMIASES
2. Trypanosomes of the type rotatorium of the frog ; and
3. Long, thin trypanosomes without free flagellum, of a distinc-
tive type.
Concerning the natural mode of spread of the infection we have
only Schaudinn's work, mentioned in Chapter III. ; he regards Culex
pipiens as the carrier of the infection. [We have seen, however, that
this is doubted by several authorities.]
CHAPTER XV
TRYPANOSOMES OF REPTILES
Until 1902 we knew nothing definite about the trypanosomes of
reptiles. It is true authors mentioned that the tortoise served as a
host to trypanosomes, but they gave no exact details. From the
existence of flagellates with undulating membrane in the digestive
tract of Ixodes testudinis, an acarine ectoparasite of tortoises, Leydig^
concluded, without positive proof, that they existed in the blood of
the tortoises.
Later, Kunstler^ writes : ' In the blood of the mud tortoise there
occurs a parasite which, I think, is allied to Trypanosoma.'
In 1902 we found on two occasions out of four in an Asiatic
tortoise, Damonia reevesii, a trypanosome which we have described
under the name T. damonice.^ We reproduce here our description,
with diagram (Fig. 62, and Fig. 11 in the coloured plate) :
' In the two infected tortoises T. damonics was very scanty in the
blood. It measures 32 fi in length (including the flagellum), by 4 /x
in width. In stained preparations it is easy to see that T. damonice
has the typical structure of the genus Trypanosoma. The body of
the parasite is usually curved, and the anterior extremity ends in a
flagellum (/). Towards the middle of the body is an oval nucleus («),
in which the chromatin is in the form of granules of variable size.
Near the posterior end is the centrosome (c), which is clearly visible,
while the convex border of the parasite is furnished with a festooned
undulating membrane (;w). The flagellum starts from the centro-
some, and borders the undulating membrane. The protoplasm is
finely granular with some larger granules, especially in the posterior
part.
' We have not seen any multiplication forms. We may add that
T. damonice is relatively stumpy, compared with the species found in
fishes and mammals. It is intermediate between these and the
T. rotatorium of frogs.'
In their paper on the trypanosomes of Gambia, Button and Todd
state that they saw trypanosomes in snakes and tortoises. They
give no details — neither of the snakes infected nor of their parasites.
1 Leydig, Lehrbuch der Histologic, 1857, p. 346.
2 Kunstler, C. R. Acad Sciences, v. 97, 1883, p. 755.
3 Laveran and Mesnil, C. H. Acad. Sciences, v. 135, October 20, 1902, p. 609.
457
458 TRYPANOSOMES AND THE TRYPANOSOMIASES
Upon the subject of the trypanosomes of the tortoise they write as
follows :
' Two tortoises obtained from the marshes at Cape St. Mary, out
of several examined, contained trypanosomes in their blood. Their
blood was constantly examined during a period of three months, but
only occasionally were parasites seen, and then only in small numbers.
Two varieties were observed. One was a
long thick form ; the other, short and
slender, possessed a comparatively broad
undulating membrane, which extended the
whole length of the organism.
' The few parasites seen in stained
films of blood from these tortoises have
not been sufficiently perfect to permit
their detailed description.'
Dr. Simond has shown us a drawing
of a trypanosome which he observed in
the blood of a tortoise at Agra, in India,
probably Emys or Kachuga tectum.
Fig. 62. — Trypanosoma
DAMONI^.
n, Nucleus. c. Centrosorae.
m. Undulating membrane.
/. Flagellum.
Gehrke^ has recorded the occurrence of
a trypanosome in a gecko.
[Minchin, Gray, and Tulloch,^ while looking for a possible verte-
brate host of the trypanosomes of tsetse-flies (see Chapter XVIII.)
in Uganda, on one occasion found a trypanosome in a film of
crocodile's blood. Beyond its large size and general resemblance to
other reptilian trypanosomes, it was not possible to make out any
details of structure in this parasite, as the blood-film was not very
well preserved. These observers found that a haemogregarine was
quite common in the blood of crocodiles.]
[Trypanosome of the Lizard. — Quite recently G. Martin^
has described a trypanosome which he found in a lizard, Mabuia
raddonii, in French Guinea.]
[This trypanosome differs from T. damonicB in appearance, and
resembles the flat form (without ridges) of T. rotatoriwn of the frog.
Examined fresh, the nucleus and centrosome are not easily made
out ; the flagellum never extends beyond the limits of the body.
When stained, the protoplasmic body of the parasite measures 40 ^
in length, by almost as much in width. The nucleus is long and
thin, and curved or arched, as in T. borreli of the frog (see next
chapter). It stains uniformly pale violet, except for one or two
darker spots. As in T. borreli, the centrosome stains deeply, and is
' Gehrke, Deutsche med. Wochenschr., 1903, ver.-beil., p. 402.
^ [Minchin, Gray, and Tulloch, Sleeping Sickness Commission Reports, No. 8,
1907, p. 130.]
^ [G. Martin, C. R. Soc. Biol., v. 62, 1907, pp. 594-596.]
TRYPANOSOMES OF REPTILES 459
in contact with one end of the nucleus. The undulating membrane
begins in the centrosome, and in its general direction describes an
arc of a circle ; it presents few folds.]
[Martin has given the name T. boueti to this trypanosome.]
[Robertson 1 has described, under the name T. pythonis, an endo-
corpuscular parasite in a python from Gambia. It has all the char-
acters of a haemogregarine, but possesses, in addition to the nucleus, a
chromatic dot like the centrosome of a trypanosome, which is joined to
the nucleus by a filament. Mesnil thinks it is premature to call this
parasite a trypanosome.]
We know nothing about the mode of propagation of the trypano-
somes of reptiles. It is very probable that it takes place by means of
ectoparasites, acarine or blood-sucking, which are not rare upon the
bodies of reptiles.
- [Robertson, ProiT. Roy. Phys. Socy. Edin., v. 16, 1906, pp. 232-247.]
CHAPTER XVI
TRYPANOSOMES OF BATRACHIANS
Section 1.— Histopical and Geog-raphical Distribution.
One year after the discovery of the first trypanosome — that of the
trout — by Valentin, Gluge/ in 1842, recorded the presence, in the
blood of frogs, of another of these parasites. He described it as a
fusiform microscopic organism with pointed ends, having on its side
three projections — probably the undulating membrane— which were
endowed with very active mobility when the parasite moved from
place to place. The body was transparent, and showed no trace of
structure.
The following year the same parasite was studied by Mayer and
Gruby. In July, 1843, Mayer ^'described it under two names:
Amceba rotatoria, a pointed parasite with two extremities; and
Paramcecium loricatum or costatum,^ an ovoid form without free
flagellum (the drawing is quite definite upon this point). In
November, 1843, Gruby* gave a fairly complete description of the
same trypanosome, and we reproduce it here in part : ' Its elengated
body is flattened, transparent, and twisted like a wimble ; its head
end terminates in long slender filaments, as also does the tail end.
The parasite is from 40 /* to 80 /* long, and 5 /* to 10 /.t wide. The
filamentous, pointed head end is very actively motile, the length of
this filament being 10 /u to 12 ij-. The body is elongated, flattened,
and serrated like the blade of a saw along one of its borders. As I
mentioned above, it is smooth and twisted two or three times
around its long axis like a wimble or a corkscrew, and on this
account I propose to call this hsematozoon Trypanosoma.''
The description is fairly precise, but the figures are not so
accurate as those of Mayer. Gruby called this species T. sanguinis.
In 1850 Chaussat,^ repeating the observations of his predecessors,
^ Gluge, Mailer's Archiv, v. 9, 1842, p. 148.
2 Mayer, ' De Organo Electrico et de Heematozois,' Bonn, July, 1843.
^ In the text the name loricaium occurs ; in the description of the plates, that
of costatum.
■• Gruby, C. R. Acad. Sciences, v. 17, 1843, p. 1134. This note is reproduced
in Ann. Sc. natur. Zool., 3rd series, v. I, 1844^ p. 104, where it is illustrated by
six figures, which prove that the author saw long thin forms and short stumpy forms.
^ Chaussat, 'Thesis for the Faculty of Medicine,' Paris, 1850, No. 192, 51 pp.
and 2 plates.
460
TRYPANOSOMES OF BATRACHIANS 461
described and figured the trypanosome of frogs, his figures being
distinctly better than those of Mayer. He has accurately drawn
and correctly interpreted the change of shape into a spherical form
with loss of flagellum.
In the same year, 1850, WedP again recorded the existence of
the trypanosome of Rana esculenia, and described for the first time a
trypanosome identical with the preceding in the blood of the green
frog {Hyla viridis). His paper gives good figures of the various
forms of these trypanosomes.
In 1870 Lieberkiihn^ figured and described under the name
Monas rotatoria a parasite in the blood of the frog which was
evidently a trypanosome.
In 1871 Ray Lankester^ rediscovered the same species in R. escu-
lenia, and gave it the name Undulina ranarum.
In 1875 Rattig* gave a further account of the parasite, and studied
the action of the following reagents upon it : alkalies, distilled water,
acetic and hydrochloric acids (which kill it almost immediately), and
salt solution, which in a strength oi ^ or ^ per cent, acts upon it
more slowly.
Gaule* devoted himself especially to establishing the non-parasitic
nature of trypanosomes, a suggestion which had already been brought
forward by Milne-Edwards, Remak, von Siebold, and Stein. He
endeavoured to establish a relation between these organisms and the
normal elements of frog's blood. Only the figures which illustrate
this paper are of any value, and two of them (iii. and v., in Fig. 2)
are good.
In 1881-1883 Grassi^ recorded the presence of T. sanguinis, Gruby
in Hyla viridis, Bufo vulgaris, and R. escidenta. He created in
addition the genus Paramcecidides for the representatives of the
family of Trypanosomata (S. Kent) with undulating membrane but
without trace of flagellum, and he recorded a species of this genus
(Paramcecioi'des costatus, n. sp.) in the blood of R. esadenia. From this
author's description and figures — a cell with a narrow and undu-
lating lateral expansion extending from the anterior extremity to
about the middle of the body — he was evidently dealing with the
' ribbed ' form of T. sanguinis, which had assumed a spherical shape.
The globular form of Amoeba rotatoria of Mayer resembled Para-
mcecium costatum.
Danilewsky,'' first in 1885 and later in 1888, gave numerous
1 Wedl, Venkschr. Akad. Wien., v. i, 1850, I plate.
^ Lieberkiihn, Ueber Bevegungserscheinungen der Zellen, Marburg and Leipzig,
1870, Table II., Fig. 17 (quoted by succeeding writers).
^ Ray Lankester, Quart. Journ. Micr. Sc, v. 11, 1871, p. 387.
* Rattig, Inaugural Dissertation, Berlin, 1875 (quoted by succeeding writers).
^ J. Gaule, of Leipzig, Arch.f. Anat. u. Physiol. (Physiolog. Abth.), 1880, p. 375,
I plate.
6 Grassi, Arch. ital. Biologie, v. 2, p. 426, and v. 3, p. 23, 1883 ; also Atti Soc.
ital. d. sc. Nat. Milano, v. 24, 1881, p. 135.
' Danilewsky, Biol. Centralb., v. 5, November i, 1885, p. 529 ; also ' Nouvelles
Recherches sur les parasites du sang des Oiseaux,' Charkov, 1889.
462 TRYPANOSOMES AND THE TRYPANOSOMIASES
details of the T. sanguinis of Gruby which he observed in the blood
of i?. esculenta, R. temporaria, Hyla arborea, and of tadpoles. In the
frog he distinguished at least four varieties. We shall return to this
again when speaking about the morphology of the parasite.
Chalachnikov,^ who has written a long account of the trypano-
somes of frogs, accompanied by numerous drawings, also groups
them into two main classes, comprising five varieties.
The work of Ziemann, published in i8g8,^ in which there is a
figure of a frog trypanosome, marks the first application of Roman-
owsky's method of staining (modified by the author) to trypanosomes.
As we have already pointed out, it is from the time that these
methods of staining were applied that our exact knowledge of the
morphology of the trypanosomes dates. Ziemann's results, it is
true, were not entirely satisfactory — he stained two chromatic
masses, a large and a small, evidently the nucleus and centrosome,
but he did not attempt to give any interpretation of them, nor did
he succeed in staining the undulating membrane or flagellum.
We took up the study of the trypanosome of R. esculenta in igoi,*
and were able to give for the first time all the details of its structure.
In addition to its intrinsic interest, that study enabled us, as we have
seen in Chapter III., to settle the question of the generic names
which should be used in designating the various trypanosomes.
In the numerous accounts to which we have just referred, it has
always been the trypanosome seen by Gluge, Mayer, and Gruby
which has been the object of study.
In November, 1903, Dutton and Todd* described two new species
of trypanosome which they found in frogs in Gambia, in addition to
T. rotatoritim or sanguinis, but it is quite likely that these were
simply special forms of the species of Mayer-Gruby.
Early in 1904 Ed. and Et. Sergent^ recorded an undoubtedly
new species of trypanosome in R. esculenta which they found in very
large numbers in the blood of a frog at Kabylie. They have called
this new trypanosome T. inopinatum.
[Continuing their researches upon the trypanosomes of frogs in
Algeria, the Sergents^ examined eighty-two specimens of R. esculenta,
with the result that T. inopinatum was found once and T. rotatorium
eighteen times. In eight of the latter cases the trypanosomes were
of the ordinary large size (40 fj- to 60 /j.), while in the remaining ten
cases the parasites were similar in form, but much smaller in size
(average length only 22 fj^). The name T. rotatoritim var. nana is
suggested by the discoverers for this smaller form.]
1 Chalachnikov, ' Recherches sur les parasites du sang,' etc., Charkov, 1888, in
Russian.
2 Ziemann, Centralb.f. Bakter., I, v. 24, 1898.
^ Laveran and Mesnil, C. R. Soc. Biol., June 22, 1901, p. 678.
* Dutton and Todd, First Report of the Expedition to Senegambia, 1902, Liver-
pool, November, 1503.
5 Ed. and Et. Sergent, C. R. Soc. Biol., January 23, 1904, p. 123.
" [Ed. and Et. Sergent, C. R. Soc. Biol., v. 58, 1905, pp. 670-672.]
TRYPANOSOMES OF BATRACHIANS 463
[Fifty-eight of the frogs were examined in summer and autumn :
forty-one of these harboured various parasites — trypanosomes, Filaria,
and Drepanidium. The twenty-four frogs examined in winter showed
no parasites.]
[Franca and Athiasi found trypanosomes in six frogs caught in
Lisbon. The parasites present were T. rotatonum and T. inopinatum
(Sargent). These authors think that the species fotatorimn should be spht
up into — (i) T. loricatum or costatum (Mayer), in which the body is ovoid,
generally fairly wide, striated or not, and with the centrosome. situated
near the nucleus ; and (2) T. rotatorium (Mayer), in which the body is
more slender, the centrosome is near the posterior extremity, and the
undulating membrane is well developed, and extends along the whole
length of the body. Mesnil thinks there is no justification for this sub-
division of the species, and that intermediate forms occur. He likewise
doubts the validity of two new species created by Franca and Athias :
(i) T. undulans, which is said to be 30 /n long, by 6 /i to g fi wide, with a
narrow undulating membrane, and without free flagellum ; and (2)
T. ekgans, which is also 30 fj, long, but only 3 /x wide.]
[Broden^ examined twenty frogs (sp. incert. ; probably two) at
Lusambo, Congo Free State, and found eighteen of them infected
with T. rotatorium. Six of the frogs also showed forms correspond-
ing to T. mega of Button and Todd ; this was probably only a
variety of T. rotatorium.']
[Lewis and Williams, in 1904, examined 140 frogs from the River
Niagara. Fourteen (10 per cent.) were infected with T. rotatorium ;
five with Drepanidium ranarum ; one with Filaria. In one case
Trypanosoma and Drepanidium occurred in the same blood. The
infections with trypanosomes were distributed as follows : In July,
of fifteen frogs examined, two were found infected ; in August, ten
out of twenty-six ; in September, two out of fourteen ; and from
October to December, of eighty-five frogs examined, none showed
trypanosomes.]
[These observers examined many other animals for the presence of
hsematozoa, but with negative results : normal cats, dogs, rabbits, and
guinea-pigs ; fifty-one English sparrows (half in winter, half in spring) ;
twenty-seven mud-puppies {Necturus maculattis) in March, and forty toads
in the summer.]
[In 1904 Laveran^ described a trypanosome which had been dis-
covered by Theiler in two Transvaal frogs {R. angolensis, Bocage,
and R. theileri, Mocquart). This trypanosome appears to be a
distinct species, to which Laveran has given the name T. nelspruit-
ense.~\
[Nabarro and Stevenson have found trypanosomes in the blood
of a frog from Hong-Kong. They were very scanty in the blood,
^ [Franca and Athias, Arch. inst. roy. de bacter. Camara Pestana, v. i, May
1906, pp. 127-165 ; abstract by Mesnil, Bull. Inst. Past., v. 4, 1906, p. 756.]
2 [Broden, Arch.f. Sch. u. Trap. Myg., v. g, 1905, p. 18.]
^ [Laveran, C. R. Soc. Biol., v. 57, 1904, p. 158.]
V
,464 TRYPANOSOMES AND THE TRYPANOSOMIASES
and the frog was also infected with a large hsemogregarine (sp. ?).
The species of frog in which these parasites occurred has not yet
been determined. Dr. Bell of Hong-Kong, to whom we are indebted *
for sending us the blood-films, has told us that the infected frog was
a small brown frog, closely allied to, if not identical with, R. tem-
poyaria.~\
[Early in 1907 Marchoux and Salimbeni^ described a new try-
panosome in a Hyla (allied to H. lateristriga, Spix and Agassiz) in
Brazil. This trypanosome is distinct from T. rotatorium, and its
discoverers have given it the name T. borreli.']
[During the past few years interesting observations have been
made upon the cultivation of T. rotatorium by Lewis and Williams^
and by Bouet;^ upon the development of T. inopinatum in leeches
and its transmission by them (Billet,* Brumpt^) ; and upon the
possible relation between the trypanosomes and hsemogregarines of
the frog. Details of these observations will be given later on.]
One of us® has observed, in specimens of the blood of a toad
(sp. ?) at Imi, Ogaden, which had been sent to him by Brumpt,
' several trypanosomes having the structure of the ordinary trypano-
somes of the frog, but much smaller in size.'
[Brumpt^ has since given a short description of this trypanosome
of the African (Somaliland) toad, Bufo reticulatus. He regards it as
a new species, to which he has given the name T. somalense.]
[In igo6 Tobey^ recorded the occurrence of trypanosomes in the
blood of newts [Diemyctulus viridescens). The trypanosomes were
constantly present in the blood and in large numbers. This is the
first time that newts have been found infected with these parasites.]
The T. rotatorium of frogs appears to occur in all parts of the
world, and in this respect it resembles the T. lewisi of rats. We
may mention that about half the frogs, R. esculenta, caught in the
neighbourhood of Paris contain trypanosomes in the blood, but
sometimes in very small numbers.
The older observers have noted that trypanosomes were seen in
the blood of frogs much more frequently in summer than in winter.
[It has already been mentioned that the Sergents in Algeria, and
Lewis and Williams in America, found the same seasonable preva-
lence of trypanosome infections in frogs.] This is the case with all
hasmatozoa, but recently Koninski of Wieliczka has stated that the
1 [Marchoux and Salimbeni, C. R. Soc. Biol., v. 62, 1907, pp. 592-594.]
2 [J. Lewis and H. V. Williams, Proc. Soc. for Exper. Biol, and Med., v. 2,
1905, p. 44, in Amer. Med., v. g, March 25, 1905 ; abstract by Mesnil, Bull. Inst.
Past., V. 3, 1905, p 413.]
^ [G. Bouet, Ann. Inst. Past., v. 20, July, 1906, pp. 564-577.]
■* [Billet, C j'?. Acad. Sciences, v. 139, 1904, pp. 574-576.]
^ [Brumpt, C. R. Soc. Biol., v. 61, 1906, pp. 167-169.]
^ Laveran, C. R. Soc. Biol., February 27, '1904, p. 332.
' [Brumpt, C. R. Soc. Biol., v. 60, 1906, p. 164.]
' \Tohty,Journ. Med. Research, Boston, New Series, v. 10, 1906, pp. 147, 148.]
TRYPANOSOMES OF BATRACHIANS 465
seasonal influence is nil} He gives statistics of the frequency with
which trypanosomes occur in the various Batrachians, but obviously
these numbers apply only to the district in which he made his
observations. He found trypanosomes in the three following species :
R. esculenta, 32'8 per cent. ; R. Umporaria, I3'2 per cent. ; and Bufo
viridis, I2"i per cent. On the other hand, trypanosomes were never
found in the blood of Hyla arborea, Bufo cinereus, and B. calamita
(very few specimens of/these three species were examined), Pelobates
fiisats (twenty-eight examined), Bombinator igneus (fifty-two examined,
of which twenty-five were larvae), and Triton vulgaris (twenty
examined).
The proportion of infected animals of a given species increases
with age. Koninski found R. esculenta infected immediately after
their metamorphosis. On the other hand, he never found tadpoles
infected as Danilewsky {loc. cit., p. 79) and Kruse^ had done. The
males of R. esculenta contained twice as many parasites as the^
females. Gruby had noticed that the proportion of infected males
was smaller than that of females.
Section 2.— Trypanosoma rotatoriuni (Mayer).^
On studying the blood of frogs {R. esculenta) infected with
trypanosomes, one is struck with the great variety of forms presented
by the parasite. All observers have drawn attention to this pleo-
morphism. Danilewsky, for example, distinguishes at least four
varieties :
1. ' The simplest form, membranous,' with a flat, transparent
body, passing insensibly into the undulating membrane, very active,
and with a long, wavy flagellum.
2. ' The flat form rolled on itself,' or the ' funnel-shaped ' form.
3. ' The plane spiral form,' with pointed posterior extremity.
The undulating membrane extends only along the anterior half of
the body.
4. ' The pectinated spiral form,' with the variety in the form of a
cornucopia.
Chalachnikov, who has made a special study of the trypanosomes
of Batrachians, distinguishes :
1. The group of flattened forms, comprising (a) the simple flat
form, (b) the folded form, and (c) the transitional form — plane spiral.
2. The group of pectinated forms, comprising (a) the pectinated
spiral form, and (6) the spiral and tubular pectinated forms (cornu-
copia).
These five varieties, of which the author gives good descriptions
' Karl Koninski, Bio/. Centrabl., v. 21, 1901, p. 40.
^ Kruse, Virchow's Archiv, v. 120, 1890, p. 557.
' The synonyms of this species are as follows : Paramecium loricatwn or
costatum-V Amoeba rotatoria [Mayer, July, 1843]=/'. sanguinis [Gruby, November,
iZ\'^ = Monas rotatoria [Lieberkiihn, \?)76\= Undulina ranarum [Ray Lankester,
1871]= T. sanguinis (Gruby) + Param(£cioides costatus n. sp. [Grassi, 1882].
30
466 TRYPANOSOMES AND THE TRYPANOSOMIASES
and figures, occur in the blood of R. esculenta, R. temporaria, and
Hyla arborea.
Chalachnikov has seen these various forms become spherical by
the retraction of the flagellum. He gives numerous figures showing
this change in vitro, and the reproduction of the parasite by seg-
mentation, which leads eventually to the formation of extremely
small spherical bodies. In the present state of our knowledge it is
impossible to say what is the significance of these bodies. [They
may possibly bear some relation to the ' morular ' masses of small
spherical bodies described byThiroux in cultures of T. paddcc, and by
Bouet in those of T. roiatorium itself.]
In ordinary fresh preparations the trypanosomes usually move
about in loco, so that one is able to study the very complex move-
ments of the undulating membrane, and the amoeboid movements
which result in the ever-varying shape of the body.
By using our ordinary method of staining we have studied the
cytological details of the structure of T. rotatorium (Fig. 63, and
Fig. 15 in the coloured plate).
The trypanosomes show a very much folded undulating membrane,
with a thickened border, which is prolonged anteriorly into a free
flagellum. These structures all stain reddish-violet by our method.
The posterior end of the flagellum (or thickened edge of the undu-
lating membrane) is situated at a variable point in the posterior half
of the body,^ and comes into relation with a vacuole, in the centre of
which is the centrosome, a fairly large granule staining deep violet.
The nucleus is oval in shape and stains pale reddish-violet. It
takes the stain uniformly, except for two or three distinct dots in it.
The nucleus is situated anteriorly to the centrosome, as in other
trypanosomes, but in this species the nucleus and centrosome are
nearly always very close together. The protoplasm stains a very
deep blue, and sometimes a number of dark blue granules are visible
in it. In addition to these, numerous unstained dots are seen, but
only in parasites that have been damaged. We have figured the two
chief varieties of T. rotatorium — the one with its surface covered with
numerous ridges or- ribs (Fig. 63, / and ^), the other flattened and
with a smooth surface (Fig. 63, 2 and 5). Both forms have the same
chromatic structure. It will be observed that in / and ^ the centro-
some is quite close to the nucleus, and, consequently, the undulating
membrane is found only along the anterior part of the body. In 2
the centrosome is about midway between the nucleus and the
posterior extremity, while in 5 it is very near the posterior end of
the body.
The anterior end usually tapers off and ends in a relatively short
flagellum. The posterior end varies much in shape. It may be
1 The undulating membrane never extends as far as the posterior end of the
body, as Senn states in his differential diagnosis, doubtless on the authority of
Gaule's inexact figures, which he reproduces.
TRYPANOSOMES OF BATRACHIANS
467
rounded off (5), or in the form of a blunt cone {2), or it may have a
short point {4.) or a very long point (/). There is scarcely any
difference between this last form and those which Button and Todd
figure (see Fig. 64) in illustration of their provisionally new species,
T. mega''- and T. karyozeukton.^
In R. esculenia in France, Laveran and Mesnil have seen parasites
with the posterior extreinity quite as elongated as those figured
by Button and Todd, and occasionally this extremity has been
Fig. 63. — Trypanosomes of Rana escuknta.
I and 4. Folded forms, thin (i), stumpy (4). 2 and 5. Flattened forms. 3. Contracted
form. Sandy. Young forms examined fresh. (Magnified about 1,400 diameters.)
n. Nucleus, c. Centrosome. m. Undulating membrane. /. Flagellum.
' Dutton and Todd found this form in a small frog (sp. ?) on McCarthy Island.
■ The figure reproduced here (Fig. 64, /) gives an idea of the well-developed undu-
lating membrane vi'ith its numerous folds, of the longitudinal striation of the body,
of the depth of staining of the protoplasm, and of the faintly-staining nucleus, all of
them characteristic of T. rotatoriiitn. The body proper is, 72 ij. long, and the
flagellum 10 /* to 1 5 m i the width of the body at the level of the nucleus is 8 m.
^ Dutton and Todd saw a single specimen of this variety in a frog (sp. ?) at
Cape St. Mary, which harboured T. roiatorium in addition. Length of body,
67-2 IJ. ; flagellum, 1 5'2 /x ; width at level of nucleus, 6-4 /i. The chief characteristic
of this parasite appears to be the presence of a chain of chromatic granules
between the nucleus and centrosome (see k in figure). The authors, however, did
not see this chain of granules in the trypanosomes of two other frogs in the same
district, although the parasites had the same general appearance as the first form,
but were smaller in size.
30—2
468 TRYPANOSOMES AND THE TRYPANOSOMIASES
so thin as to give the impression that it was prolonged into a
short flagellum. Fig. 64, 2, shows this to be almost the case with
T. karyozeukton. There is, therefore, considerable doubt as to the
validity of these new species of Button and Todd, the more so as
these observers recognise the existence of T. sanguinis^ in frogs in
Gambia.
To sum up, then, we may say that the trypanosomes of frogs
vary very much in shape as well as in size. Some of them are
relatively thin and short, others are very large and broad, and many
intermediate forms occur. The length varies from 40 /x to 60 /i, and
only exceeds this figure in forms in which the two ends are attenuated
and drawn out. The width, on the other hand, may vary from 5 /^ up
to 40 jj-. In some frogs there are found only ovoid forms with rounded
ends, a very short free flagellum, the undulating membrane extending
only half-way along the body, and which measure in films of fixed
blood 50 /x to 60 /i in length, by 30 /* to 40 /x in width.
Fig. 64. — Trypanosomes of Frogs in Gambia.
I. T. mega (Dutton and Todd). 2. T. karyozeukton (Dutton and Todd), n. Nucleus.
c. Centrosome. ft. Chain of granules extending from nucleus to centrosome.
(Magnified about i,ooo diameters.)
Fig- 63, 3, represents a form which is not uncommon, and has
often puzzled observers. Some, such as Mayer and Grassi, have
looked upon it as a new species, and even as a new genus {Para-
mcecioides, Grassi). It is nothing more than an ordinary trypano-
some which has become spherical, probably owing to the abnormal
conditions met with outside the bloodvessels. Both varieties, the
pectinated and the smooth, may exhibit this change of shape into
spherical form, and we have on several occasions seen the change take
place. The undulating membrane is retracted, and in the fresh con-
dition the flagellum seems to have disappeared. The examination of
stained specimens does not show any difference in structure between
this form and the normal forms. The forms represented in Fig. 63,
6 and 7, seen in a drop of fresh blood, appear to us to be very young
forms of trypanosomes.
All the foregoing remarks apply to the parasites seen in R. escu-
lenta. Observers are agreed in regarding as very closely allied, if not
identical, the parasites of R. temporaria, of Bufo, and of Hyla. We
' They found this parasite in fourteen out of thirty-five frogs examined (/?.
irinodis (?) and other species).
TRYPANOSOMES OF BATRACHIANS
469
of H. arborea,
have had the opportunity of studying a number of trypanosomes in
the blood of a Hyla arborea, bought at a shop in Paris. Fig. 65
represents a trypanosome of the Hyla. It is 75 /* long, flagellum
included, by 7 /^ in width, and in general appearance it closely
resembles a young T. rotatorium of Rana esculenta.
We have sought in vain for reproduction forms of T. rotatorhcm
in our frogs.
[Fran9a and Athias^ examined 143 specimens
var. meridionalis, six of which were found to be
infected with T. rotatorium. The trypanosomes
were very numerous in the blood of these frogs,
much more so than is usually the case in R.
esculenta. ~\
[In stained films, in addition to the ordinary
forms of trypanosome (resembling that seen in
Fig. 65, except that the nucleus was fusiform,
elongated, and fairly narrow), there were others
which appeared to be forms undergoing division
by segmentation. In blood-films fixed imme-
diately after they were made only the initial phases
of division were seen — the first division of the
centrosome, and the conversion of the nucleus
into a pale, ill-defined area bounded by a ring
of small chromatic masses.]
[In blood fixed five hours after leaving the
bloodvessels, and kept between slide and coverslip,
more advanced stages of division were observed.
Areas of cytoplasm became more or less (but
never completely) divided off, and in them two
nuclei and two centrosomes were seen. There were also appear-
ances almost suggesting mitotic division, and Fran9a and Athias
think that ' in the division of trypanosomes by segmentation the
blepharoplast possibly plays a role like that of the centrosome
during mitotic division.']
[Marchoux and Salimbeni^ have found a new trypanosome in a
H. lateristriga (?) from Brazil. In the fresh condition the young
forms are seen to differ considerably from the adult forms of the
parasite. The young parasites are morphologically like T. rota-
torium. The undulating membrane is clear and transparent, and is
quite distinct from the granular cytoplasm of the body. In the adult
forms the protoplasmic portion is very expansive and rolled on itself,
so that the undulating membrane comes to lie inside a cigar-shaped
body which is open at both ends. When pressure is applied to the
film containing the trypanosomes the body becomes flattened out.
There is no free flagellum extending beyond the limits of the body.]
1 [Franga and Athias, C. R. Soc. Biol., v. 60, 1906, p. 1108.]
^ [Marchoux and Salimbeni, C. R. Soc. Biol., v. 62, April 19, 1907, pp. 592-594.]
470 TRYPANOSOMES AND THE TRYPANOSOMIASES
[When stained — and Billet's^ method gave the best results — the
protoplasm and centrosome were found to take the stain readily ;
the nucleus and chromatic filament, on the other hand, stained
badly. The nucleus has a curious shape ; it is a long, narrow,
arched body, with a rod-like prolongation at one end. The total
length, including the terminal rod, which measures 5 /-i to 6 /*, is
25 H' to 30 /i. The centrosome is situated at the anterior extremity
of the nucleus. This arrangement of the nucleus and centrosome is
similar to that previously described by Fran9a and Athias^ in a
trypanosome from another species of Hyla.]
[The total length of this trypanosome is from 20 /* to 80 /j.. Mar-
choux and Salimbeni regard this trypanosome of H. lateristriga (?)
as a new species, to which they have given the name T. borreli.]
[Cultivation of T. rotatorium. — Lewis and Williams {op. cit.)
were the first to achieve any success in this direction. They used
nutrient agar, to the water of condensation of which two or three
drops of frog's or toad's blood were added. Cultures made from
two infected frogs showed, after two weeks, growths of flagellated
organisms. These were of a very long oval form, the largest
measuring 18 /* by 2 /x. There was one long flagellum attached to
a centrosome situated at the anterior end of the body. The largest
parasites showed a rudiment of an undulating membrane. Motility
was not very marked. Numerous small forms were seen, evidently
representing various developmental stages.]
[The growth was never luxuriant, and rosette formation was not
observed. Only one generation of subcultures was successful, and
all the cultures soon died. A single attempt to inoculate a normal
frog gave a negative result.]
[Attempts to cultivate Drepanidkmi did not succeed, although the
parasite remained alive for a long time in the medium. In one of these
experiments trypanosomes were found in the tubes after ten days, and it
appeared as though trypanosomes had dewelo-ped. horn Drepanidium . This
was not so, however ; the trypanosomes had evidently been introduced
with the blood of the frog which served for the preparation of the rnediuni,
for an uninoculated tube of the batch also showed trypanosomes. This
1 [Billet, C. R- Soc. Biol., v. 61, 1906, pp. 753, 754. Billet's method is a modifi-
cation of Giemsa's method, which I have found to give very good results with
trypanosomes, malarial and other . chromatin-containing parasites, as well as with
ordinary blood.]
[It is prepared as follows: Add o'3 per cent, of sodium carbonate to a r per
cent, solution of Grubler's medicinal methylene blue, and heat to 50° C. for three
hours. This is called the ' carbonated blue.' To stain films, put 10 c.c. distilled
water plus 10 drops of commercial Giemsa's solution in a graduated cylinder or
test-tube, add 2 or 3 drops of the ' carbonated blue ' ; shake and pour the mixture
into a dish (see p. 9) containing the film, which is previously fixed for a few
seconds in absolute alcohol, or in a mixture of alcohol and ether. Keep in the
parafBn-chamber at 45° to 50° C., and at the end often to fifteen minutes the film
will be well stained. Wash in a large quantity of water, and if too dark decolourize
rapidly with a few drops of tJnna's solution of tannin-orange.]
^ [Franja and Athias, Arch, de I'Insi. royal de bacter. Camara Pesiana, v. i,
fasc. 2.]
TRYPANOSOMES OF BATRACHIANS 471
is comparable with Novy and McNeal's observations and culture experi-
ments upon the avian trypanosomes.]
[Bouet^ has been more successful in his culture experiments
than have Lewis and Williams. He obtained excellent results with
Novy and McNeal's blood-agar medium (original formula, see p. 452),
the best proportion being one of agar to two of blood. In this medium
cultures grew in four or five days at the room temperature. At the
time Bouet's paper was written (July, 1906) the organism was in the
tenth generation of subculture. In subcultures the trypanosomes
appeared at the end of a very variable time — from three days up to
twenty-five or even thirty-four days. The average time was from
six to ten days on Novy and McNeal's type medium. The trypano-
somes were most numerous from the eighteenth to the twenty-fifth
days.]
[Both forms of the trypanosome, the stumpy and the thin forms, seen
in the original frog's blood, gave positive results on cultivation. The
majority of the frogs whose blood was cultivated harboured other parasites
(filariae and hsemogregarines), in addition to T. wtatorium. A frog which
had only trypanosomes in its blood gave positive results. On the other
hand, frog's blood in which hsemogregarines were alone present gave
negative results.]
[In young cultures the young trypanosomes were sometimes
agglutinated into rosettes, but it was especially towards the end
of the first month that auto-agglutination was observed in moist
coverslip preparations of the culture. As has been observed by
McNeal in cultures of T. lewisi, by Novy and McNeal in cultures of
avian trypanosomes, and by Thiroux in cultures of T. duttoni, colonies
may appear upon the agar medium above the water of condensation,
especially in old cultures.]
[The vitality of cultures is very great. In one case living try-
panosomes were found after five months in a culture-tube of the
third generation.]
[Morphology of T. rotatoriuni in Cultures (see Fig. 66). — In the
fresh condition the majority of the parasites are fusiform or pear-
shaped, like Herpetomonas or Crithidia. The protoplasm is finely
granular, and the nucleus and centrosome are hardly discernible.
It is difficult to make out an undulating membrane. There is a very
long, actively motile flagellum. Movement takes place with the
flagellar end foremost, and in agglutination (which is usually only
temporary) the flagella are, as a rule, directed towards the centre of
the rosette.]
[In addition to the above forms, which are by far the most
numerous, all intermediate stages between them and the forms seen
in the blood of frogs may be met with, especially in the earliest
generations of cultures. In old cultures spherical forms are common,
' [Bouet, Ann. Inst. Past., v. 20, 1906, pp. 564-577.]
472 TRYPANOSOMES AND THE TRYPANOSOMIASES
and these often contain very refractile, round, non-staining granules,
consisting possibly of reserve material.]
[Multiplication is by longitudinal fission. In the colonies vi^hich
grow on the agar itself the trypanosomes occur in ' morular ' form.
The ilagellum is very short and hardly motile, and the protoplasm
contains small, very refractile granules. These are possibly early
stages of a resistant form of the parasite, as has been suggested when
speaking of the cultivation of T. padded (p. 449).]
[The trypanosomes seen in cultures are much smaller than those
seen in the blood of frogs. The long forms are about 25 /*, flagellum
included, by 2 /* ; the spherical forms are 5 j" in diameter.]
[Stained Preparations. — The best results were obtained by Gray
and TuUoch's method (see p. 12), and then staining with Giemsa for
Fig. 66. — Culture forms of T. rotatorium. (After Bouet.)
In I the centrosome is posterior to the nucleus. In 2 the centrosorae is anterior to the
nucleus, and a well-marked undulating membrane is present. 3 is a young form, in
which the undulating membrane has not yet developed. 4, a very young spherical
form undergoing division. (Magnified about 1,800 diameters. )
three-quarters of an hour to one hour. The film is finally cleared
with clove oil for about a minute.]
[The nucleus is usually situated near the anterior end of the
body, especially in the Herpetomonas-iorms ; but it may be centrally
or' even posteriorly situated (Fig. 66, / and 2). The centrosome is
always near the nucleus, between it and the anterior end of the
body ; sometimes it actually touches the nucleus. The flagellum is
attached to the centrosome. An undulating membrane is present in
the adult culture forms (Fig. 66, 2), but not in the young forms (j).]
[Spherical forms may occur in very young or very old cultures.
In the former they are to be regarded as very young trypanosomes,
already possessing the power of division (Fig. 66, ./), in the latter
case as involution forms, which will eventually give rise to the
' morular ' stage and the stage of ' encystment.']
[As has already been stated, auto-agglutination may occur in
cultures. Usually the flagella are directed towards the centre of the
rosette, but sometimes they may be directed peripherally.]
TRYPANOSOMES OF BATRACHIANS 473
[The serum of an infected frog was found to possess agglutinating
properties ; that of a normal frog, or of another species of animal,
had no agglutinating properties.]
[Frogs injected intraperitoneally with cultures did not become
infected. Negative results were also obtained on inoculating speci-
mens of Bufo and Pelobates.']
In conclusion, we may add that the type T. rotatorium is the
largest of the trypanosomes hitherto known. There are several
species, particularly amongst the parasites of fishes, which are as
long as, and even longer than, this trypanosome, but in none of
them does the width exceed 15 ^. On account of its usually stumpy
appearance, its very short flagellum — which in some cases appears
even to be wanting — and its amcebiform changes of shape, T. rota-
torium stands alone in the genus Trypanosoma, and it is easy to
understand why an attempt was made, when our cytological know-
ledge of the trypanosomes was still in its infancy, to create a new
genus for the thin and slender trypanosomes of mammals. Now we
are acquainted with a whole series of species intermediate between
the very large and stumpy T. rotatorium and the trypanosomes of the
type lewisi ; and, moreover, in the species rotatorium itself all kinds
of intermediate forms are to be found.
Section 3, — Try2)anosoma inoinnatxim, Sergrent.
We cannot do better than reproduce the authors' own figure and
description of this parasite :
' When examining the blood of a green frog {R. escnlenta) caught
at Dra-el-Mizan, Kabylie, we found a trypanosome which does not
resemble any of the hitherto described trypanosomes of frogs and
Batrachians generally.
' The parasite is about 25 /^ to 30 *i long — flagellum included — by
3 fj- wide. It closely resembles T. lewisi of rats, but differs from it in
being more stumpy and less drawn out, especially in the post-centro-
somic portion, and its nucleus is situated near the middle of the
body, whereas in T. lewisi it is in the anterior part of the body. The
centrosome is well developed, as in T. lewisi, and often it appears as
a transversely elongated body occupying the whole width of the
parasite. The undulating membrane is usually unfolded, and
appears even more rigid than that of T. lewisi. Although the blood
preparation may show as many trypanosomes as red blood cor-
puscles, all the parasites seen are of about the same size, and, indeed, we
have only once seen a dividing form of the parasite (Fig. 67, A) which
showed two centrosomes and commencing division of the undulating
membrane adjacent to them. The two centrosomes were situated
close to the nucleus instead of occupying the normal position of the
centrosome. In several other parasites we have also seen the centro-
474 TRYPANOSOMES AND THE TRYPANOSOMIASES
some close to the nucleus, which, in all probability, means that these
parasites were about to divide.
' This trypanosome of green frogs is undoubtedly different from
T. rotatorium, Mayer ( = T. sanguinis, Gruby), which is the only
trypanosome hitherto recorded in this species of frog. It resembles
not only T. lewisi and the other mammalian trypanosomes, but also
the trypanosomes of fishes, especially T. remaki of the pike, described
in detail by Laveran and Mesnil. We shall call it Trypanosoma
inopinatum.
' Other frogs in the same locality were not infected, and frogs
from other parts of Algeria showed the ordinary frog trypanosome,
T. rotatorium.'
Fig. 67. — T-ftypANosoMA inop/xatum o¥ R. esculenta.
A. Commencing division. A red corpuscle of the frog is shown for the purpose of
comparison. (Magnified about 1,000 diameters.)
[During the past few years Billet and Brumpt have made several
interesting observations upon T. inopinatum, particularly with regard
to its development in leeches and its possible relation to Dre-
panidium.
[In his first paper 1 upon the subject Billet states that he saw the
trypanosomes (T. inopinatum) penetrate the red blood-corpuscles of the
frog, at the same time losing the flagellum. In addition to these trypano-
somes, the frog's blood contained (i) numerous free gregarinoid forms
(Billet says that the analogy between some of these forms and the trypano-
some-forms mirtus flagellum is striking) ; (2) endoglobular, elongated
forms, undergoing longitudinal division ; and (3) rounded forms, giving
rise to all stages of schizogony, characteristic of the Hcemogregarina splendens
(a Laitkesterella).^
[In his recent paper^ Billet brings forward evidence to show that the
alternate or invertebrate host of T. inopinatum is a leech, Helohdella algira.
1 [Billet, C. R. Soc. Biol., v. 57, 1904, pp. 161 -164 ; abstract by Mesnil in Bull.
Inst. Past., V. 2, 1904, p. 724.]
2 [Billett, C. S. Acad. Sciences, v. 139, 1904, pp. 574-576 ; abstract in Bull. Inst.
Past., V. 2, 1904, p. 989. See also Woodcock's article in 0,uart. Journ. Micr. Sc,
V. 50, 1906, p. 251.]
TRYPANOSOMES OF BATRACHIANS 475
Trypanosomes were frequently found in the intestine of the leeches which
had been ectoparasitic on frogs, harbouring either haemogregarines plus
trypanosomes or haemogregarines alone. The T. inopinatiim found in the
leeches showed a variety of forms which were never met with in the
frogs' blood. The leech, therefore, appears to be the normal host of this
trypanosome.]
[Twenty-four or more hours after the infection of the leeches, their
intestine contains forms, with a distinct nucleus and centrosome, which
seem to be stages intermediate between a hsemogregarine and a trypano-
some. After the third day only T. inopinatum axe present. Lastly, frogs
apparently free from all haematozoa, infected by the bites of leeches
containing only trypanosomes, contracted an infection exclusively haemo-
gregarine. From these observations Billet concludes that T. inopinatiim
is ontogenetically related to the haemogregarine parasite in R. esculenta in
Algeria.]
[Brumpt^ found in the digestive tract of leeches {Placohdella catenigera),
which had sucked the blood of an African tortoise, Emys leprosa (probably
containing the Hamogregarina bagensis), forms (? ookinetes) with a nucleus
and a smaller chromatic body, resembling the centrosome of a trypano-
some.]
[In a later paper 2 Brumpt states that he was able to infect frogs with
T. inopinatum by allowing infected leeches to bite them. In one frog the
trypanosomes appeared in the blood on the tenth day after the bite of the
leech. They multiplied rapidly, and on the thirtieth day there were fifty
trypanosomes to one red corpuscle. The frog became very anaemic, and
died on the thirty-fifth day. Similar results were obtained with other
frogs, thus showing that T. inopinatum may be pathogenic]
[Brumpt showed, moreover, that T. inopinatum is inoculable. Frogs,
inoculated in the dorsal lymph sac with the heart blood of frog (i) men-
tioned in the preceding paragraph became infected in forty-eight hours,
and died in twelve to sixteen days. Post-mortem there were found
cedemas, hydropericardium, ascites, and haemorrhages. Heart puncture
furnished a ' purulent, . chylous fluid,' containing many agglutinated
trypanosomes.]
[The trypanosomes in the leech rapidly gave rise to Herpetomonas-
forms varying in length from 6 /i to 14 /x for the body and 3 /a to 14 /* for
the flagellum.]
[Brumpt is of opinion that there is no relation between the trypano-
somes and the haemogregarines of the frog. Leeches fed on frogs
containing many haemogregarines did not develop flagellates in a month.
We have already seen that Lewis and Williams, Novy and McNeal, and
others are of the same opinion.]
Section 4. — Other Trypanosomes of Batraehians.
Trypanosoma nelspruitense, Laveran, 1904.^ — This trypano-
some from Nelspruit, Transvaal, was discovered by Thaller in two
frogs. There appear to be at least two species of frogs in the
Transvaal : R. angolensis, Bocage, and a new species to which
Mocquart has given the name R. theileri.]
[T. nelspruitense varies in size. Its length may be as much as
70 /*, of which the free flagellum may occupy 35 /j- ; the width is 3 fj..
1 [Brumpt, C. Ji. Soc. Biol., v. 57, 1904, pp. 165-167; abstract by Mesnil
(reproduced above) in Bull. Inst. Past., v. 2, 1904, p. 724.]
2 [Brumpt, C. R. Soc. Biol., v. 61, 1906, pp. 167-169.]
' [Laveran, C. R. Soc. Biol., v. 57, 1904, p. 158.]
476 TRYPANOSOMES AND THE TRYPANOSOMIASES
The body is slender and vermiform in appearance, much like
T. granulosum of the eel. The anterior two-thirds of the body
stains much more intensely than the posterior third, and anteriorly
there are many deeply staining granules. The nucleus is round or
oval, and stains less deeply than the centrosome. The latter is
situated at a variable distance from the posterior end. The undu-
lating membrane shows several folds.]
[Trypanosome of Frogs in Hong-Kong (Fig. 68). — This
trypanosome was found by Nabarro and Stevenson in blood-films
of a frog sent to them by Dr. J. S. Bell, of Hong-Kong. The try-
panosomes were extremely scanty, only two being found in several
large blood- films. The frog was more obviously infected with a
large haemogregarine,^ and it is conceivable that if this frog's blood
had been cultivated and the trypanosomes had developed, it might
Fig. 68. — Trypanosome of Frogs in Hong-Kong.
Note the great width of the undulating membrane, and the unusual position of the
nucleus, to which the centrosome is closely applied. A red corpuscle is also repre-
sented to show the relative sizes. (Magnified about 1,500 diameters.)
have been thought that the hsemogregarines had given rise to the
trypanosomes.]
\_Morphology. — The larger of the two tr5'panosomes seen was 41 jj-
long, including the free flagellum, which measured 16 /i*. The body
itself was long and slender, its greatest width being only about i'4 /*.
The nucleus was small and spherical, and about i'3 /^ in diameter,
Its posterior edge was partly overlaid by the centrosome, which was
about 7"5 /t from the posterior end of the body. There was a large
vacuole i //. from the posterior extremity, and another smaller one
close to the centrosome. Stained by Giemsa's method the cyto-
plasm (blue) was seen to be fairly homogeneous, no striations or
chromatic granules being visible in it. The nucleus was stained a
reddish-violet and the centrosome a deep violet. The undulating
membrane was distinctly visible (pale reddish-violet) ; it was very
wide (2"5 /x in the widest part) ; the edge was wavy, but the mem-
brane itself showed few folds.]
^ [Professor Laveran, to whom I sent the films, informs me that this hsmo-
gregarine resembles that which he had observed in a frog from the Transvaal.]
TRYPANOSOMES OF BATRACHIANS 477
[The other trypanosome was 25*6 /* long, including the flagellum,
3 /*. The total width of the parasite was 3"8 f^, that of the body
itself being i"g //.. The nucleus was spherical, i'3 /^ in diameter, and
more irregularly stained than in the first trypanosome. The centro-
some was 4"6 /x from the posterior end of the body, and in close
contact with the nucleus. There was a small vacuole just behind
the nucleus and centrosome. The posterior half of the body was
much more deeply stained than the anterior.]
[This trypanosome appears to be different from the hitherto
described species of frog trypanosomes. I think it is a new species,
for which I propose the name Trypanosoma belli.~]
[Trypanosome of the Toad (Trypanosoma somalense, Brumpt,^
igo6). — This trypanosome was found by Brumpt in the blood of a
Somaliland toad, Bufo reticulatus. The body is arched as it is in
some forms of T. rotatorium. T. somalense differs from the latter in
its small size, the body measuring 30 /x and the free flagellum 7 jjl.
The centrosome is 4 /* from the posterior end. The nucleus is
situated in the widest part of the body, a little anterior to the
centrosome.]
[Trypanosome of the Newt. — This trypanosome was found
by Tobey^ in American newts (Diemyctulus viridescens) . The infected
newts appeared to differ from healthy newts in the following respects:
they were darker in colour, the spots on the side were a brighter red,
and the shoulder and pelvic girdles were very prominent owing to
the wasting of the muscles. They seemed as active as healthy
newts, but some of them died soon after they came under observa-
tion.]
[In the fresh condition the trypanosome was very active, and
moved with a spiral motion. The whole body was contractile.]
[In stained specimens three different forms were seen : ' wide,
long, and short.' The first two seemed to be but different phases of
a contractile state. The average length was 45 fi to 50 /x, the width
2 jLi to 5 /x, the free flagellum 24 i^. The nucleus was situated slightly
behind the middle of the body. The centrosome, which was small
and often difficult to see, was situated in the centre of an unstained
vacuole a short distance from the posterior extremity of the body.
The undulating membrane was well developed and showed several
folds.]
[Inoculations into healthy newts were unsuccessful, as were
inoculations into mud puppies {Necturus maculatus). Several at-
tempts were made to infect frogs, but in only one case was there an
apparent infection.]
1 [Brumpt, C. R. Soc. Biol., v. 60, 1906, p. 164.]
2 [E. N. loh^y. Journ. Med. Research, new series, v. 10, No. I, igo6, pp. 147,
148.]
478 TRYPANOSOMES AND THE TRYPANOSOMIASES
Section 5.— Modes of Infection.
We are quite ignorant of the mode of infection of frogs and the
other Batrachians. It is quite probable that it occurs through the
agency of some ectoparasite, such as the leech or tick. The same
remarks apply to the haemogregarines of the Batrachians, and it is
to be hoped, now that attention has been drawn to these questions,
that some definite information will soon be forthcoming.
[We have seen, however, that the recent investigations of Billet
and Brumpt (see Section 3) have furnished a reply to these ques-
tions. The T. inopinatum of frogs can undoubtedly multiply in the
intestine of the leech, and infected leeches are able to transmit the
infection to healthy frogs by biting them.]
We have tried to infect green frogs experimentally with the
blood of other frogs containing trypanosomes. The infective blood
was injected into the dorsal lymph sac or into the peritoneum. We
experimented upon seven or eight frogs, with only one successful
result.^ One frog inoculated on June 30, 1902, showed a few para-
sites in its blood from the 4th to the 8th of July.
Why were these experiments unsuccessful ? Perhaps on account
of the mode of inoculation, but it is nearly always successful with
the trypanosomes of fishes and rats. Possibly it was because the
frogs experimented upon had acquired immunity as the result of a
previous infection, for, as a matter of fact, they were got from dis-
tricts where about half the frogs were infected.
' [It has already been mentioned (see p. 475) that Brumpt succeeded in trans-
mitting T. inopinahim to several green frogs by inoculation into the dorsal lymph
sac]
CHAPTER XVII
TRYPANOSOMES OF FISHES
Section 1. — Historical. Species known to be Infected.
In 1841 Valentin saw in the blood of a trout {Salmo fario) a parasite
which he classed with the Amoebse of Ehrenberg,^ but which, from
the short description and figures he gives of it, should be grouped
with the hsematozoa to which Gruby in 1843 gave the name
trypanosomes.
Remak observed in the blood of the pike {Esox lucius) and of
several other fresh-water fishes very motile hsematozoa, possessing a
transparent membranous part and tooth-like projections, which dis-
appeared when the parasites were at rest.^ In all probability these
were trypanosomes, for in fresh preparations the undulating mem-
brane gives one the impression of tooth-like projections, as described
by Remak.
Gros^ recorded the existence of vermicules in the blood of a
number of fishes — -gudgeon, rockling, perch, sterlet, lote, tench, etc.
The parasite of the rockling was 45 jx long, by i /« wide, and was very
active. It was pleomorphic, but most frequently presented the
appearance of a ribbon folded and twisted into various shapes.
From this description one cannot fail to recognise these parasites as
trypanosomes.
Berg and Creplin have described the trypanosome of the pike,
which was seen by Berg in four cases out of five. He states that the
length of the parasites is from one and a half to three times the large
diameter of the red corpuscles.*
The haematozoa found by Wedl in the gudgeon and in a tench
appear to belong rather to the hasmogregarines than to the trypano-
somes.'
Chaussat found in the blood of the barbel a hsematozoon
resembling the trypanosome of the frog."
1 Valentin, ' .-Vrchiv. de J. Mtiller,' 1841, p. 435.
2 Remak, Canstatfs Jahresbericht, 1842, p. 10.
3 Gros, Bull, de la Soc. i?np. des Natur. de Moscow^ 1845, v. 18, part i., p. 423.
* Berg, ' Hamatozoen des Hechtes,' Archiv skand. Beitrdge zur Natur-
geschichte, 1845, v. i, p. 308. — Creplin, Observations upon Berg's communication.
5 Wedl, Denk. der Wiener A kad. der JVissen., 1850, part ii., p. 15.
6 Chaussat, ' Thfese,' Paris, 1850.
479
480 TRYPANOSOMES AND THE TRYPANOSOMIASES
In 1883 Mitrophanov^ gave a good description of two species of
fish trypanosomes under the names of Heematomonas cobitis and
H. carassii. From his descriptions and figures it is obvious that
these parasites belong to the genus Trypanosoma.
T. cobitis was found in the blood of a loach (Cobitis fossilis). Its
length is given as 30 /* to 40 /^, and its breadth as i /^ to i"5 /^.^ The
body is elongated and worm-like, and has a spirally-arranged undu-
lating membrane. The two ends are pointed, and the one which is
foremost when the parasite moves ends in a flagellum.
T. carassii was found in the blood of the Prussian carp (Carassins
vulgaris). It is much larger and more flattened than the preceding,
which, however, it otherwise closely resembles. These trypanosomes
are very nearly related to the trypanosome of the pike, which is
described later on.
Danilewsky found trypanosomes in Cyprinus carpio, Tinea tinea,
Cobitis fossilis, and C. barbatula, Esox lucius, Perca fluviatilis, and
Carassius vulgaris.^ According to Danilewsky, two kinds of trypano-
some are to be distinguished in fishes — a thin, ribbon-like form and
a spindle-shaped form, each of them with an undulating membrane
and a flagellum. They multiply by unequal binary division.
Chalachnikov* found trypanosomes in the blood of a large number
of fishes caught in the rivers and streams in the district of Cherson,
Russia, notably in the Cypriiius carpio, Esox lucius, Carassius vulgaris,
and Acerina vulgaris. He recognises two kinds of trypanosome in
fishes : (i) A flat form very closely resembling the flat trypanosome
of the frog. A variety of this trypanosome is said to have two
flagella — a long anterior and a short, thin posterior one. (2) A
fusiform trypanosome with undulating membrane arranged spirally.
There would appear to be three varieties of this form, but they are
not sharply marked off from one another.
The young trypanosomes of fishes may, according to Chalach-
nikov, multiply by longitudinal division. He states that he also saw
in the blood of Cyprinus carpio and Esox lucius, kept for some days
in vitro, protoplasmic masses undergoing division, as well as young
trypanosomes.
Kruse^ says that he has often seen herpetomonads (trypanosomes)
in the blood of fishes from the Mediterranean Sea.
According to Lingard,^ the fresh-water fish of India often
harbour trypanosomes which sometimes are very numerous. In
form these trypanosomes appear to be allied to the species de-
scribed by Mitrophanov. Fishes which live in the mud are more
■> Mitrophanov, Biol. Centralbl., March 15, 1883, vol. 3, p. 35.
2 [These are the dimensions given by Mitrophanov. In the original of Laveran
and Mesnil's book the width is incorrectly given as \ ft.]
3 Danilewsky, Biol. Centralbl., November I, 1885 ; and 'Rech. sur les parasites
du sang des Oiseaux,' Charkov, 1889.
* Chalachnikov, ' Recherches sur les parasites du sang,' Charkov, 1888.
5 Kruse, in ' Flugge,' v. 2, 1896, p. 627.
^ Lingard, ' Report on Surra,' etc., v. 2, part i., 1899, p. 155.
TRYPANOSOMES OF FISHES 481
often infected than other kinds. Lingard found trypanosomes in
the following species : Trichogaster fasciatus, Ophiocephalus striatus,
Macrones seenghala, and M. tengara (Siluridas). It is during the
months of May and June that trypanosomes are seen in largest
numbers in the blood of these fishes.
[Lingard^ has since made a further study of the fish trypanosomes in
India. He has found trypanosomes in the following species from the
river at Poona : Barhus carnaticus, Ophiocephalus striatus, and Rhynchob-
della aculeata. The trypanosomes were obtained by gently scraping the
gills without drawing blood. In fish from the River Jumna, Lingard found
two species of trypanosome — a large form in Ophiocephalus striatus and a
small one in Trichogaster faciatus and Macrones seenghala or M. tengara.~\
Sabrazes and Muratet have described the trypanosome of the eel.-
We were the first to describe trypanosomes in salt-water fish —
sole, ray, and dogfish — and we also discovered a trypanosome
peculiar to the red-eye, for which we have created a new genus,
Trypanoplasma? We give below a list of the fresh-water and salt-
water fishes that we have examined for trypanosomes. The number
or word in brackets after the specific name of each fish refers to the
number of specimens examined.
Fresh-Water Fishes.
A. Fishes in which Trypanosomes were found. ■ — ■ Pike,
Esox Lucius (6) ; carp, Cyprinus carpio (g) ; tench. Tinea tinea (10) ;
red-eye, Scardinius erythrophthalmus (many) ; bream, Abramis brama
(4) ; eel, A nguilla vulgaris (many) .
B. Fishes in which Trypanosomes were not found. —
Gudgeon, Gobio gobio (many) ; loach, Cobitis barbatula (many) ;
stickleback, Gasterosteus aculeatus (many) ; roach, Leuciscus rutilus (3) ;
chub, Squalius {Leuciscus) cephalus (several); trout, Trutta fario (4).
Salt-Water Fishes.*
A. Fishes in which Trypanosomes were found. — Cartila-
ginous fishes : Ray, Raja punctata (11), Raja mosaica (3), Raja
clavata (i). Raja maerorynchus (i) ; small dogfish, Seyllium eanicula
(38) ; large dogfish, Seyllium stellare (3). Bony fishes : Sole, Solea
vulgaris (21).
B. Fishes in which Trypanosomes were not found. —
Cartilaginous fishes: Mustelus eanis (5) ; Galeus galeus (2) ; Acanthias
1 [Lingard, Ind. Med. Gaz., December, 1904, pp. 445-447 ; abstract by Mesnil
in Bull. Inst. Past., v. 3, p. 414.]
2 Sabrazfes and Muratet, 'Trypanosome of the Eel' (resum^ of communica-
tions made to the Socidte hnndenne de Bordeaux, in December, 1901, March, 1902,
and July 2, 1902).
' Laveran and Mesnil, C. R. Acad. Sciences, October 28, i9oi,and October 13,
1902 ; also Arch. f. Protistenkunde, 1902, v. i.
^ These fishes were obtained from the waters of Roscoff, or from those of
L'anse St. Martin (.St. Martin's Bay), near Cap de la Hague (Manche).
31
482 TRYPANOSOMES AND THE TRYPANOSOMIASES
acanthias (ii) ; Squatina angelus (4 — 2 large and 2 small) ;
Torpedo torpedo (2) ; Raja alba (3) ; Raja microcellata (2) ; Raja
mirelatus (i). Bony fishes : Syngnathtis sp. (many) ; Nerophis lum-
bricoides (several) ; Orthagoriscus mola (2) ; Blennius pholis (many) ;
Blennius montagui (many) ; Callionyinus dracunculus (2) ; Gunnelus
. vulgaris (5) ; Lophius piscatorius (5) ; Gobius sp. (many) ; Midlus
surmuletus (4) ; Trigla (4) ; Scomber scomber (i) ; Trachurus trachnrus
(2); Cottus scorpius (several); Coitus bubalis (18); Zeus faber (2);
Pagellus centrodontus (2) ; Pagellus erythrinus (7) ; Cantharus griseus
(i) ; Chrysophrys aurata (i) ; Labrus sp. (many) ; Crenilabms
melops (6); Spinachia vulgaris (4); Ammodytes tobianus (7); Ammo-
dytes lanceolatus (7) ; Gadus pollachius (10) ; Gadus luscus (4) ; Lo/u
molva (2) ; Motella tricirrata (8) ; Motella mustela (4) ; Rhombus
maximus (2) ; Platessa vulgaris (it) ; Platessa microcephala (5) ; other
Pleuronectes, sp. var. (several) ; Lepadogaster gouanii (many) ; Conger
conger (10).
From these lists it is seen that trypanosomes are rare in the bony
salt-water fishes, and that the cartilaginous fishes are more often
infected.
[The investigations of the past few years have considerably
extended the list of fishes in which trypanosomes are known to
occur. They have also made known some interesting facts con-
cerning the evolution of the fish trypanosomes in the body of par-
ticular species of leech.]
[Several new species of Trypanoplasma have been described in
the blood of fishes, and, in addition, Leger^ has described one, which
he calls Trypanoplasma intestinalis, in the oesophagus and anterior
part of the stomach of a salt-water fish, Box bodps.~]
[Of the recent observations upon the trypanosomes of fishes the
following may be mentioned : Petrie ^ found a number of goldfish [Caras-
sius auratus) infected at Elstree, Hertfordshire. This trypanosome closely
resembles T. danilewskyi of the carp, with which Petrie thinks it is
identical.]
[Robertson^ has found trypanosomes in Pleuronectes flesiis, P. platessa,
and Raja microcellata caught at Millport, Scotland.]
[Montel* found a trypanosome resembling that of the eel in the blood
of a fish of the genus Clavias (Silunts clarias) in Cochin China. He has
given it the provisional name T. claria.]
[Neave^ has found trypanosomes in several species of Nile fish, the
noke {Mugil), the dabib (Polypterus), the bagara [Bageus bayard), and the
gargur [Lynodontis schal).']
[Castellani and Willey^ describe trypanosomes in several fish caught
in a lake in Colombo, Ceylon. To one of them, found in a member of the
1 [Ldger, C. R. Soc. Biol., v. 58, 1905, pp. 511-513.]
2 \?eXx\^,Journ. of Hyg., v. 5, April, 1905, p. 197.J
^ [Robertson, Proc. Roy. Phys. Soc. Edin., v. 16, 1906, pp. 232-247.]
* [Montel, C. R. Soc. Biol., v. 58, June 17, 1905, p. 1014.]
* [Neave, Second Report of the lVellco7ne Research Laboratory, 'K\\3.r\.ovim,'iC)o6f
P- '97-]
^ [Castellani and Willey, Quart. Journ. Micro. Sc, v. 49, 1905, pp. 383-402.]
TRYPANOSOMES OF FISHES 483
Siluridse, Saccohranchus fossilis, they have given the name T. saccohranchi.
Trypanosomes were also found in Macyones cavasius and Gobius giuris.^
[The trypanosome of the eel, first described by Sabrazfes and Muratet
in 1901, has been found by Manca^ in eels (eight out of seventeen
examined) from different parts of Oristano, Sardinia.]
[Dr. Bell has informed me that in Hong-Kong he found a large
trypanosome (? T. granulosum) in eels.]
[Brumpt and Lebailly^ have briefly described a number of new fish
trypanosomes, many of which were associated in the same host (marine
Teleostians) with new hsemogregarines. The following species of fish
were found to be infected : Pleuronectes platessa {Platessa vulgaris), plaice ;
PL flesus (Flesus vulgaris), flounder ; Limanda platessoides ; Platophrys
lateyna; Bothus rhombus {Rhombus lavis), brill ; Bhnniiis pholis ; Gobius niger ;
Callionymus dracunculiis ; and Cothis bubalis.~\
[In addition to the above, Brumpt ^ has described several new species
of trypanosome and of trypanoplasm in fresh - water fishes, as well as
their mode of evolution in particular species of leech. The new
trypanosomes were found in Barbus fluviatilis, barbel ; Perca fluviatilis,
perch; Acerina cernua ; Coitus gobio, river bull-head; Scardinius erythroph-
thahmis, rudd or red-eye ; various species of Leticiscus, roaches ; Gobio
fluviatilis, gudgeon ; and Squalius {Leuciscus) cephalus, chub. A trypano-
some found in the minnow (Phoxinus lavis) is regarded by Brumpt as a
new species, but Laveran* thinks it has all the characteristics of T. dani-
lewskyi of the carp.]
[The new trypanoplasms described and named by Brumpt were found
in C otitis gobio ; Barbus fluviatilis ; Abramis brama,hxea.va.; and Salmo fario,
trout.]
[L6ger,* in 1904, described a new trypanosome as well as a new
trypanoplasm in Cobitis barbatula, loach.]
[Lastly, Keysselitz^ states that he has found both trypanosomes and
trypanoplasms in the following fishes obtained from various German
waters : Perca fluviatilis, Acerina cernua. Lota vulgaris, Barbus fluviatilis,
Cyprinus carpio, Carassius vulgaris. Tinea vulgaris, Abramis brama, Leuciscus
idus, L. cephalus, L. erythrophthalmus, L. rutilus, Esox lucius, and Cobitis
barbatula. Trypanosomes {Trypanosoma) were found alone in Anguilla
vulgaris and Silurus glanis.]
[The trypanosomes of fishes belong, therefore, to two genera
— Trypanosoma and Trypanoplasma. The latter genus comprises
several species, in addition to that originally described by Laveran
and Mesnil in the red-eye and minnow {Tpl. borrdi), and that
described shortly after by Miss Plehn'' in the carp (,Tpl. cyprini).
Trypanosomes of both genera are now known to occur in several
species of fish — carp, loach, river bull-head, red-eye, barbel, bream,
minnow, and others.]
1 [Manca, C. R. Soc. Biol., v. 60, 1906, p. 494.]
^ [Brumpt and Lebailly, C. R. Acad. Sciences, v. 139, 1904, p. 613 ; Lebailly,
Md., p. 576.]
2 [Brumpt, Rev. Scientif., September, 1905, pp. 321-332 ; abstract by Mesnil,
Bull. Inst. Past., v. 3, p. 920. Also C. R. Soc. Biol., v. 57, 1904, pp. 161 164 ; and
V. 60, 1906, pp. 160-162, and 162-164.]
* [Laveran, C. R. Soc. Biol., v. 57, 1904, pp. 250, 251.]
^ [Ldger, C. R. Soc. Biol., v. 57, 1904, pp. 344, 345.]
'' [Keysselitz, Arch.f. Protisten., v. 7, 1906, pp. 1-74]
' [Plehn, Arch.f. Protisten., 1903, v. 3, p. 175.]
31—2
484 TRYPANOSOMES AND THE TRYPANOSOMIASES
Section 2.— Technique. Presepvation of the Trypanosomes
of Fishes.
Examination of Living Parasites. — Several drops of blood
can be easily obtained from a fish by incising two or three rays at
the base of the caudal fin. An ordinary fresh preparation is made
and at once examined for trypanosomes. If it be desired to preserve
the blood in hanging-drop preparation or for subsequent inoculations,
the addition of a little citrated salt solution will prevent coagulation,
but leave the motility of the trypanosomes unimpaired.
The trypanosomes of fishes can live for several days in vitro.
Berg (loc. cit.) kept the trypanosomes of the pike alive for six days at
12° C. in an ordinary blood preparation. Mitrophanov succeeded in
keeping them alive for three or four days in blood mixed with salt
solution. He states that a fairly low temperature is favourable to
their preservation {loc. cit., p. 39), which agrees with our own
observations upon T. lewisi.
Chalachnikov {loc. cit.) states that he saw in the blood of Cyprinus
carpio and Esox lucius, kept for several days in vitro, protoplasmic
masses undergoing division, which he looked upon as multiplication
forms of the trypanosomes. Possibly the trypanosomes of fishes
may become agglutinated in vitro, as other trypanosomes do, which
would explain certain of the forms described by this observer.
We have kept the trypanosomes of the pike alive for several
days in pure blood and in blood mixed with salt solution, but we
have not observed the division forms described by Chalachnikov, or
any agglutination of the parasites. In order to see agglutination
easily, it is obviously necessary that the trypanosomes should be
fairly numerous in the blood, which we have never found to be the '
case with the parasites of fishes. Possibly the fishes examined by
Chalachnikov were more severely infected than our own, and conse-
quently agglutination was able to occur.
Sabrazes and Muratet^ kept the trypanosomes of the eel alive
in vitro for eight days at a temperature of 10° to ig° C.
[Lebailly^ succeeded in keeping trypanosomes of the eel alive for
nine days in ordinary slide and coverslip preparations, ringed with
vaseline and kept at 24° C. For the first four to five days there was
a definite multiplication of the parasites.]
The method of staining fixed specimens of blood is the same as
that previously given, but in order to obtain good results certain
special precautions are necessary. The fishes must be opened while
still living and blood taken from the heart with a pipette. The
blood is then spread in a thin layer on slides, rapidly dried over the
flame of a spirit-lamp, and fixed in absolute alcohol or in alcohol and
ether. The atmosphere is saturated with water-vApour at the sea-
side, and consequently blood-films dry so slowly in the ordinary way
' Sabrazes and Muratet, Soc. de Biol., January i6 and 30, 1904.
2 [Lebailly, These Fac. Med., Paris, 1906; also Arch. parasitologie, v. 10, 1906.]
TRYPANOSOMES OF FISHES
485
that the corpuscles and parasites have time to become altered in
appearance. In the blood of dead fishes the blood-corpuscles and
trypanosomes undergo rapid changes.
Section 3.— Description of the Trypanosomes of Fishes
belonging- to the Genus Trypanosoma.
We shall consider first the trypanosomes of fresh-water fishes,
and later those of salt-water fishes.
Trypanosoma semaki, Laveran and Mesnil, igoi. ■ — We have
given the name T. remaki to the trypanosome of the pike, after
Remak who first saw the parasite.^
This trypanosome appears to have a wide geographical distribu-
tion — Remak, Berg, Danilewsky, Chalachnikov, and we ourselves
have seen it in the pike in various parts of Europe. The infection
Fig. 69. — Trypanosomes of the Pike.
2, 3. T. remaki var. parva. 4. T. remaki var. magna, n. Nucleus, c. Centrosome.
m. Undulating membrane. /. Flagellum. (Magnified about 2,000 diameters.)
is also a fairly frequent one ; thus, in Paris, as in Lorraine, we
found parasites in three out of four pike weighing 500 grammes or
more. The trypanosomes are never very numerous, and they are
sometimes so scanty that a prolonged examination is necessary in
order to find a single parasite.
In fresh blood T. remaki looks like a minute worm endowed with
very active movements, with an undulating membrane along one
side. It wriggles and twists about more than T. lewisi, and often
becomes rolled on itself. Its structure can only be satisfactorily
made out in stained specimens.
Most infected pike show parasites differing much in length, so
that we have described two varieties of T. remaki (var. parva and
magna).
T. remaki var. parva measures on an average 28 ju. to 30 /n in
length, including the flagellum, the body itself being 15 /* to 20/i
' Laveran and Mesnil, Acad, des Sciences, October 29, 1901.
486 TRYPANOSOMES AND THE TRYPANOSOMIASES
long. Some specimens we have measured were as much as 42 /j. in
length (body 25 /*, flagellum 17 /*), whilst others were only 20 /^ long
(body and flagellum each 10 /i). This variation in length appears to
be independent of the process of division, for we have seen it when
there were no dividing forms. The width of the parasites is about
1-4 fj..
Fig. 6g, /, 2, and j, gives a good idea of this variety of T. remaki.
The protoplasm of the body stains pale blue, is fairly homogeneous,
and no definite granules can be seen in it.' The nucleus (») and the
centrosome (c) are stained deep violet. The nucleus, usually oval in
shape, is situated at the junction of the anterior and middle thirds
of the body. It is composed of fine chromatic granules closely
packed together and surrounding a central vacuole, in which there is
often seen a granule larger than the rest. The spherical centrosome
is small compared with those of the other species of piscine trypano-
somes. The flagellum borders the undulating membrane and
joins the centrosome. The undulating membrane is not much
folded, showing at the most five or six folds, and is very like that of
T. lewisi. The part of the body posterior to the centrosome is very
short and bluntly conical.
T. remaki var. magna (Fig. 69, 4) is at least 45 /* long (body 26 [j. to
28 jj) hy 2 jj. to 2"5 iJ. wide. Some specimens may be as long as 57 /*.
Besides the difference in size, this variety differs from the variety
parva by the darker staining of its protoplasm, which may be partly
due to the greater thickness. As in the case oi parva, the protoplasm
stains evenly, no granules being visible. In other respects the two
varieties are practically identical — -the nucleus has the same struc-
ture in both, the centrosome is close to the posterior end, and the
undulating membrane is slightly folded.
These large trypanosoraes are not forms undergoing division, for
we have never seen any specimens of T. remaki showing signs of
division.
In naturally infected pike we have never seen undoubted dividing
forms, but have occasionally met with parasites of the variety parva
with two nuclei. We have only met with dividing forms in the two
pike experimentally inoculated. The pike from which these two
were inoculated contained only the small variety of T. remaki,
and all the parasites seen in these two experimentally inoculated
pike likewise presented the appearances of the variety parva. The
trypanosomes showed the same variations in length as did those of
the naturally infected pike, and during the ten to fifteen days that
the parasites were most numerous in the blood dividing forms were
not infrequently met with.
Trypanosomes about to undergo division increase a little in size,
and especially in width. The length of such parasites varies from
28 /i to 35 /x. The nucleus may divide first, as in Fig. 70, 3, but
more often the centrosome is the first to divide {2 and ^).
TRYPANOSOMES OF FISHES
487
The centrosome enlarges (/) and then divides into two small
spherical masses. These are at first quite close together, but soon
separate, remaining joined for a time by a small connecting portion,
thus giving rise to the appearance of a dumb-bell. At the same
time the root of the flagellum divides {2 and 4), and afterwards the
fla,gellum divides throughout its whole length.
The nucleus when about to divide becomes elongated in the long
axis of the parasite (/ and 7). The nuclear vacuole and its chromatic
granule also elongate and divide, so that the chromatin becomes
concentrated at the two extremities of the nucleus. Finally, there
are two nuclei, one behind the other (Fig. 70, 3 and 5), each con-
taining a vacuole with a chromatic granule. The nuclear division
Fig. 70. — Different Stages in the Longitudinal Division of T. remaki.
(Magnified about 2,000 diameters.)
is of the direct type. At a given moment the trypanosome shows
two nuclei, two centrosomes, two undulating membranes, and two
flagella; the protoplasm then quickly divides. The division is equal
or subequal, so that the newly formed trypanosomes are not easily
distinguished from the older ones. This mode of division is identical
with that of T. hrtwei.
Do the large and the small forms which we have described con-
stitute distinct species ?
In the pike which contained the two varieties parva and magna
we did not find intermediate forms of the parasite. The large
trypanosomes do not always coexist with the small ones. Finally,
inoculations made with the small variety reproduced only small
forms of the trypanosome. These facts are in favour of a specific
diiference, but they are not conclusive. On the other hand, the
great resemblance between the small and the large trypanosomes
except for the size, is in favour of their being a single species.
Possibly the trypanosomes of the variety magna only appear in pike
which have been infected for a long time with the variety parva.
488 TRYPANOSOMES AND THE TRYPANOSOMIASES
We hope that this question will be answered by the experimental
method we have initiated.
Trypanosoma danilbwskyi, Laveran and Mesnil, 1904. — Dani-
lewsky was the first to record the existence of trypanosomes in the
carp {Cyprinus carpio), and for this reason we have given his name
to this species. We found T. danilewskyi in one out of four carp
from Garches (Seine et Oise), and in two out of three carp, 14 to
15 centimetres [about 6 inches] long, bought in Paris. These obser-
vations were made in March, 1903. In September and October, 1901,
the blood of two carp bought in Paris had given negative results.
It is an interesting fact that we have often found small leeches fixed
between the scales on the bodies of the carp, especially those coming
from Garches. The trypanosomes were always very scanty in the
infected carp.
Fig. 71. — Trypanosomes of the Carp and of the Tench.
I. T. danilewskyi. 2 and 3. T. tinea. (Magnified about 2,000 diameters.]
T. danilewskyi (Fig. 71, /) is 35 /ti to 45 /u. long, by about 3 /a wide,
the free flagellum measuring 15 ytt to 17 /x. The undulating mem-
brane is broad and has many folds. The centrosome is fairly large
and is close to the posterior extremity. The nucleus is elongated,
and is situated towards the middle of the body, but usually rather
nearer the anterior end. The protoplasm contains chromatic
granules varying in size and number. We have not seen any
multiplication forms.
We have already mentioned that another trypanosome, Trypano-
plasma cyprini, Plehn, has been found in the carp. This hsematozoon,
which is quite distinct from T. danilewskyi, will be described later.
[The trypanosomes found by Petrie in nineteen goldfish (Carassius
auratus) examined at Elstree apparently belonged to this species.
The parasites were scanty in every case. In the fresh condition
they were very active and showed many contortions. The length of
three individuals was 32 /^, 38*4 /^, and 48 /^ respectively ; the width
was 2 /i to 3 /i.]
TRYPANOSOMES OF FISHES 489
[Attempts to cultivate this trypanosome on rabbit-blood agar
were unsuccessful. Short ' tadpole ' forms, not very active, were
seen in the culture tube in ten days, and on the eleventh and
twelfth days small groups of four or five parasites were present.
Petrie regards these flagellates seen in culture as degeneration
forms.]
[A minnow {Phoxinus Icevis) examined by Laveran harboured a
trypanosome having all the characteristics of T. danilewskyi of the
carp. In addition to this trypanosome, a trypanoplasm, apparently
identical with that of the red-eye {Tpl. borreli), has been found in the
minnow by Leger and by Laveran.]
Trypanosoma tincm:, Laveran and Mesnil, 1904. — We found
trypanosomes in three out of six tench (Tinea tinea) bought alive in
Paris in March, 1903. Tench from 20 to 25 centimetres [8 to 10 inches]
long were more often and more severely infected than j'ounger ones
from 12 to 15 centimetres long. We had previously examined
this fish on several occasions (in Lorraine,, August, igoi ; in Paris,
September and October, 1901), but with negative results.
The trypanosomes were scanty or very scanty in the infected
tench, but in one the parasites were fairly numerous in the blood,
and particularly so in the kidneys.
Doflein had previously recorded the occurrence of trypanosomes
in the tench. The fish found infected by him were obviously ill,
and died in large numbers.^
In fresh blood the trypanosome is very motile, and is nearly
always rolled on itself, so that one is unable to make out its shape
and structure. It is necessary to study stained specimens in order
to ascertain the details of structure.
The parasite is about 35 /^ long, by 2 '5 /^ to 3 /n wide. Its posterior
end is in the form of a short, blunt cone (Fig. 71, 2, j), and the
centrosome, which is fairly large, is not far from the posterior end.
The nucleus is situated towards the middle of the parasite ; the
undulating membrane is wide and shows several folds. The free
flagellum is fairly long.
In several parasites the centrosome and root of the flagellum had
divided, so there is little doubt that in this case, as in that of
T. remaki, multiplication takes place by equal division or bipartition,
although we did not succeed in finding more advanced stages of
multiplication.
Trypanosoma ABRAMis, Laveran and Mesnil, 1904. — In July, 1902,
we found trypanosomes in the blood of a bream {A bramis brama) caught
in the River Sarthe, between SabI6 and Avoise. Unfortunately the
fish died, and the blood on its arrival in Paris was already too decom-
posed to allow of a study of the trypanosome.
The blood of three bream bought in Paris did not contain
trypanosomes.
1 Doflein, 'Die Protozoen,' etc., Jena, I901, p. 71.
490 TRYPANOSOMES AND THE TRYPANOSOMIASES
[We shall see later that Brurapt has described a new trypano-
plasm, which he calls Tpl. ahramidis, in the bream.]
Trypanosoma granulosum, Laveran and Mesnil, 1902. — Sabraz^s
and Muratet, of Bordeaux, were the first to give a description of the
trypanosome -of the eel {Anguilla vulgaris), which we have called
T. granulosum. The infected eels were caught in the Garonne at
Portets, and were from 25 to 30 centimetres [10 to 12 inches] in
length. Eels of about the same size caught at various other places
in the West of France did not harbour trypanosomes.
Six eels, caught in the River Sarthe, near Sable, in July, were
examined by us, and this trypanosome was found in every case.
The parasites were scanty in the blood. Of nine eels examined at
Roscoff in August, 1902, only one showed trypanosomes in the blood,
and they were very few in number. We have looked in vain for
trypanosomes in the blood of eels from the ponds at Garches, as well
as of those bought in shops in Paris.
[We have already mentioned the fact that trypanosomes have
been found in eels in Sardinia (Manca), in Hong-Kong (Bell), and
in Germany (Keysselitz).]
In fresh specimens we have only been able to make out the great
contortions of the body in many cases, and the large size the para-
sites may attain.
In stained preparations trypanosomes of all sizes are found. The
largest are 80 /j, long — body 55 /^, flagellum 25 /* — by 2*5 /z to 3 /j. wide.
We measured two others which were smaller : one was 70 /i long,
the flagellum being 30 jj. ; the other was 44 /" long, of which the
flagellum measured 13 p.. T. granulosum is shown in Fig. 72, 2, and
in Fig. 13 of the coloured plate.
[In eels caught in the sea Lebailly found a trypanosome which is
smaller than that of eels caught in rivers. He calls this marine eel
trypanosome T. granulosum var. parva.^
The posterior extremity beyond the centrosome is very short and
rather pointed, while the anterior end is very pointed. The centro-
some is spherical and relatively large. There is a well-developed
undulating membrane, bordered by a flagellum which stains par-
ticularly well. The protoplasm contains large granules scattered
throughout the length of the body. These granules stain deep
violet, and often appear upon an almost unstained background.
They are sometimes grouped around the nucleus, which is then
seen with difficulty. The nucleus stains reddish-violet, and is com-
posed of a mass of chromatic granules. Sometimes it occupies the
whole width of the body ; at other times, when it is narrower, it lies
close to the concave side.
Sabrazes and Muratet found that the trypanosomes of the eel can
live for more than a week in blood kept in vitro at a temperature of
10° to 19° C.^ Under these conditions the authors observed multi-
1 Sabrazes and Muratet, oc. Sde Biol , January 16 and 30, 1904. [It has already
been mentioned that Lebailly kept them alive for nine days at 2+° C]
TRYPANOSOMES OF FISHES
491
plication of the trypanosomes, and young forms as well as dividing
forms became quite common. Sabrazes and Muratet also succeeded
in cultivating this trypanosome according to the method of McNeal
and Novy. Attempts should be made to get a series of subcultures
of T. granulosum, as has been done with T. lewisi.
Trypanosoma solem, Laveran and Mesnil, igoi. — We found this
parasite in only one of four soles (Solea vulgaris) caught in
St. Martin's Bay, near Cap de la Hague, in the province of
Manche. The trypanosome was very scanty in the infected sole,
which harboured in addition the H csmogregarina simondi}
At Roscoff we also found trypanosomes in the sole, but in even
a smaller proportion than among the fish caught in St. Martin's
Bay.
In fresh blood T. solea looks like other trypanosomes ; its move-
m
Fig. 72. — Trypanosomes of the Sole and of the Eel.
I. Trypanosome of the sole. 2. Trypanosome of tbe eel. (Magnified about 2,000
diameters.)
ments are very active, and the undulating membrane, with the free
flagellum at the anterior end, can be distinguished.
In stained specimens the following details can be made out
{see Fig. 72, i, and Fig. 12 in the coloured plate) : The parasite is
40 /x long, the flagellum, which is very short, measuring only 8 jj..
The anterior extremity is often less pointed than the posterior.
The oval nucleus, containing large chromatic granules, is situated
about the middle of the body. The spherical centrosome is near
the posterior extremity, and is considerably bigger than in T. remaki.
The undulating membrane is well developed and the flagellum is
well seen in stained specimens. The protoplasm contains several
small chromatic granules in the posterior part of the body, and also
shows some fine longitudinal striations.
Trypanosoma scyllii, Laveran and Mesnil, 1902. — We found this
trypanosome at Roscoff in sixteen out of thirty-eight small dogfish
1 Laveran and Mesnil, C. R. Acad. Sciences, v. 133, October 14, 1901.
492 TRYPANOSOMES AND THE TRYPANOSOMIASES
{Scyllium canicula), and in one out of three large dogfish (Scy Ilium
stellare), examined. i
The trypanosome is nearly always rolled on itself, so as to form
in fresh blood and even in stained specimens an almost complete
circle bordered by the undulating membrane. The extremities,
which are often folded under and hidden by the body of the para-
site, are not easily examined. Fig. 73, /, shows a T. scyllii in a
blood-film stained in the usual way. Its length is from 70 /x to 75 /x,
the flagellum measuring about 14 /.i, and its width is 5 /* to 6 yii.
The posterior extremity is conical and not very pointed. The proto-
plasm, which is finely granular, stains a deep blue by our usual
method, and is easily distinguished from the undulating membrane,
which is pale blue. The round or oval nucleus is situated at the
junction of the anterior and middle thirds of the body. The centro-
some, situated near the posterior end, is smaller than in T. solecB.
The flagellum joins the centrosome and borders the undulating
Fig. 73. — Trypanosomes of the Dogfish and of the Ray.
I. T. scyllii. 2 and 3. T. raja, (Magnified about 1,600 diameters.)
membrane, which is broad, and presents several well-marked folds.
We did not find any multiplication forms. The parasites were
always scanty in the blood of the dogfish examined.
Trypanosoma rajje, Laveran and Mesnil, 1902. — We found this
trypanosome at Roscoff in Raja punctata in all of four medium-sized
or large fish examined. The blood of seven small rays gave negative
results. It was found also in one R. macrorynchus examined, in one
R. mosaica out of three examined, and in the one R. clavata examined
(from St. Martin's Bay). The blood of R. alba, R. microcellata, and
R. mirelatus gave negative results.
We think that the trypanosomes found in R. punctata, R. mosaica,
R. clavata, and R. macrorynchus belong to the same species, but we
are not sure of this. The description which follows applies to the
trypanosomes oi R. punctata and of i?. mosaica, studied in fresh blood
and in stained films.
1 In our earlier papers we followed E. Moreau (' Manuel d'Ichthyologie fran-
gaise,' 1902, p. 6) in giving to the small dogfish the name Sc. stellare (catnltis), and
to the large the name Sc. canicula. There is no doubt that in Moreau's work the
names of the two dogfish were transposed by mistake.
TRYPANOSOMES OF FISHES 493
T. rajcs is 75 /* to 80 /* long, by about 6 /t wide, the flagellum
measuring about 20 fi. The posterior extremity is usually very
pointed, so much so that it sometimes seems to end in a flagellum.
The various intermediate forms of the posterior end and its staining
reactions show, however, that this is not a flagellum. Fig 73, 2,
shows a trypanosome of the ray with such a pointed posterior end.
Fig. 73, J, shows a trypanosome of the same species with a conical
posterior end, and looking quite different from the parasite seen in
Fi&- 73> ^- The trypanosome with the blunt end bears a close
resemblance to T. scyllii.
The protoplasm stains a dark blue and contains fine chromatic
granules. The round or oval nucleus is situated at the junction of
the anterior and middle thirds of the body. The centrosome, small
and round, stains deeply, and is situated a considerable distance
from the posterior end, especially when this is very pointed. The
flagellum joins the centrosome and is very thin, both where it borders
the undulating membrane and in its free part. Fig. 14 in the coloured
plate shows a T. rajce as it appears in films stained by our method.
We have never seen any multiplication forms. These trypano-
somes, which are always scanty in the blood, appear to have no
pathogenic action.
[The following is a brief description of the more recently described
trypanosomes of fishes :
[Trypanosoma claria (Montel, 1905). — This trypanosome was found in
a Clarias [Silurus clarias) in Cochin China. In fresh preparations it is
fairly active, but less so than T. lewisi. When stained its length is about
60 /i, and its breadth about 4 ij. ; there is a short free flagellum. The
posterior end is thick and truncated ; sometimes it appears bifid. The
anterior end tapers off towards the free flagellum. The protoplasm stains
a deep blue, but in the anterior half of the body there are clear areas,
which stain badly, and about the middle of the body in the region of the
nucleus there are some longitudinal striae. The nucleus is large and
feebly staining ; it contains chromatic granules, one of which is larger
than the rest. The centrosome is large, and stains very deeply ; it is
situated near the posterior end of the body. There is a well-developed
undulating membrane with numerous folds. The free flagellum is short,
and does not stain very well.]
[r. clarice resembles T. scyllii, T. raja, and especially T . granulosum. It
is thinner than the first two and a little broader than the last.]
[Trypanosoma platessa (Lebailly, 1904). — Total length, 52 /*; width,
3 /x to 3'5 /i ; free flagellum, 12 /x. There are numerous granules in the
cytoplasm ; the nucleus is at the junction of the anterior and middle
thirds of the body. The posterior extremity is very pointed. The host is
a plaice, Pleuronectes platessa {Platcssa vulgaris), which is found to harbour
also a new hasmogregarine, Hamogregarina platessa. About one in six of
the fish examined was infected with the trypanosome.]
[Trypanosoma flesi (Lebailly, 1904). — Total length, 55 fj.; width, 5 ju ;
free flagellum, 10 jx. The cytoplasm contains numerous granules ; the
nucleus is situated about the middle of the body. The posterior end of
the body is pointed, and the centrosome is rather nearer the tip than in
T. platessa. The host is Pleuronectes flesus {Flesus vulgaris), flounder, which
494 TRYPANOSOMES AND THE TRYPANOSOMIASES
harbours in addition a new hsemogregarine, H. flesi. About 25 per cent,
of the fish examined were found to be infected.]
[Trypanosoma laterncd (Lebailly, 1904). — Total length, 65 /* ; width,
5 /i to 6 yu ; free fiagellum, 8 /*. The cytoplasm contains large and
numerous granules. The host is Platophrys laterna, in which a new
haemogregarine, H. laternce, is also found. Only one in twenty of the fish
examined was infected.]
[Trypanosoma limanda (Brumpt and Lebailly, 1904). — Total length,
45 /x; width, 2 /i to 2-5 /i ; free flagellum, 20 /x. The posterior end of the
body is very pointed. The host of this trypanosome is Limanda platessoides,
one in six of which was found to be infected.]
[Trypanosoma delagei (Brumpt and Lebailly, 1904). — This trypano-
some is thin and fusiform, like the foregoing, but is rather shorter. Total
length, 33 /x ; width, 2-5 // ; free flagellum, 12 /x. The posterior extremity
is pointed ; the undulating membrane is almost as wide as the body itself.
As in T. limanda, the nucleus is nearer the centrosome than 'the free
flagellum. The host is Bhnnius pliolis, which harbours in addition the
Hamogregarina higemina (Laveran and Mesnil). About 4 per cent, of the
fish were found infected with this trypanosome.]
[Trypanosoma gohii (Brumpt and Lebailly, 1904). — Total length, 66 /x ;
width, 5 ;" to 5'5 ;(i ; free flagellum, 10 /x. The posterior extremity of
the body is generally blunt or rounded off The host is Gohiiis niger, in
which two new haemogregarines are found, H. hlanchardi and H. gohii.
About half the fish were found infected.]
[Trypanosoma callionymi (Brumpt and Lebailly, 1904). — Total length,
70 fj. ; width, 5 /x ; free flagellum, only 5 /x. The cytoplasm sometimes
contains large granules. The posterior extremity of the body is long and
tapering, and as a result the centrosome is situated some distance from
the tip. The host is Callionymus dracunadus (about 20 per cent, infected) ;
two new haemogregarines, H. callionymi and H. quadrigemina, are associated
with this trypanosome.]
[Trypanosoma coi^J (Brumpt and Lebailly, 1904). — Total length, 53 /x;
width, 5 /x ; free flagellum, 8 /x. The posterior end is short and rounded.
The host is Coitus bubalis (three out of four found infected). This
species of Coitus harbours also a new haemogregarine, H. cotii.]
[These new trypanosomes of Brumpt and Lebailly belong to two
types : (l) The type of T. rajce of Laveran and Mesnil, in which the
body-is long and fairly wide (45 /x to 65 /x in length, by 5 /x to 7 /x in
width), and the free flagellum short (5 fx to 10 /"). To this type
belong T. flesi, T. gobii, T. callionymi, T. cotti, and T. laterncB.
(2) The type of T. lewisi, in which the body is short and thin (20 /x
to 25 /x long, by 2 /x to 2*5 /x wide), and the free flagellum is fairly long
(12 /x to 20 |u). To this tyoe belong T. limandcB and T. delagei. The
T. platesscB is intermediate between these two types.]
[The haemogregarines found in these fishes are also of two types.
H. quadrigemina and H. gohii axe. 17 /x long, by i'8 /x broad, and resemble
H. higemina and H. simondi of Laveran and Mesnil. All the others are
shorter and wider (9 /x to 12 /x long, by 2 /x to 3 /x wide). The haemo-
gregarines and trypanosomes frequently coexisted in the same fish, and
the trypanosomes were always much scarcer in a given species than the
haemogregarines. ij
1 [From Mesnil's abstract in Bull. Inst Past., v. 2, 1904, p. 990].
TRYPANOSOMES OF FISHES 495
[Trypanosoma bothi (Lebailly,i 1905). — Total length, 42 /^ ; width,
3 ju ; free flagellum, 13 yu. The posterior end is thin and tapering. The
nucleus is situated in the anterior half of the body. The host is Bothus
rhombus {Rhombus lavis), brill, which harbours also a new hsemogregarine,
H. bothi.]
[Trypanosoma barbi (Brumpt," 1906). — Total length, 51 /i ; width, 3 yu, ;
free flagellum, 16 /x, The centrosome is I'S P- from the posterior end.
The nucleus is 14 jj. from the origin of the free flagellum, and 18 /t
from the posterior tip. The host is Barhis fluviatilis, barbel, in which a
trypanoplasm also occurs.]
[Trypanosoma perccB (Brumpt, 1906). — Total length, 57 /x ; width,'
3 /J. ; free flagellum, 16 ju. The centrosome is i'5 yu. from the posterior
end ; the nucleus is equidistant from the anterior and posterior ends of
the body. The host is Perca fluviatilis, perch.]
[Trypanosoma acerina (Brumpt, 1906). — Total length, 47 jx ; width,
3/i; free fragellum, 17 /*. The centrosome is i'5 jx from the posterior
end ; the nucleus 8 jj. from the origin of the free flagellum, and 19 /* from
the posterior extremity of the body. The host is Acerina cernua.']
[Trypanosoma phoxini (Brumpt, 1906). — In the adult forms the dimen-
sions are as follows : Total length, 46 /x ; width, 5 jm ; free flagellum,
12 /i. The centrosome is i'5 jx from the posterior end; the nucleus is
equidistant from the anterior and posterior ends of the body. In young
forms the absolute and relative dimensions are a little different. The
host is Phoxiniis lavis, minnow, which harbours also the Trypanoplasma
borreli.']
[It has already been mentioned that Laveran regards this trypanosome
of the minnow as identical with T. danilewskyi of the carp.]
[Trypanosoma langeroni (Brumpt, igo6). — Total length, 50 fj.; width,
3 [J. ; free flagellum, 13 ;«. In old forms the width may be 5 yu to g yu, and
the free flagellum 10 /x. The centrosome is i"5 /* from the posterior end ;
the nucleus is 16 yu. from the origin of the free flagellum, and 18 /x from
the posterior end. The host is Cottus gobio, which harbours also a
trypanoplasm.]
[Trypanosoma scardinii (Brumpt, 1906). — Total length, 54 yix ; width,
4 ,u. ; free flagellum, 18 ix. The centrosome is 2 ai, from the tip, the
nucleus 13 fx from the origin of the flagellum, and 19 /x from the posterior
end. The host is Scardinius erythrophthalmus, red-eye, in which a trypano-
plasm also occurs.]
[Trypanosoma leiicisci (Brumpt, 1906). — Total length, 48 fx ; width,
3 jx ; free flagellum, 18 /x. Centrosome, i'5 yu from tip ; nucleus, 9 /x from
origin of flagellum, and 18 yu. from the posterior end. This trypanosome
is parasitic in various roaches, Leuciscus genus.]
[Trypanosoma elegans (Brumpt, 1906). —Total length, 51-5 fi; width,
4-5 yix; free flagellum, 15 fx. Centrosome, 2 fx from tip; nucleus, 15 jx
from origin of flagellum, 17 yix from posterior end. The host is Gobio
fluviatilis, gudgeon.]
[Trypanosoma squalii (Brumpt, J 906). — This was seen only in the fresh
condition in the blood of Squalius (Leuciscus) cephalus, chub. In size and
general appearance it resembled the trypanosome of the gudgeon.]
These various trypanosomes, which were found by Brumpt in
fresh-water fishes, can be divided into, several groups according to
their mode of evolution in the bodies of leeches, Hemiclepsis (see
Section 5).
1 [Lebailly, C. i?. Soc. Biol, 59, 1905, p. 304.]
2 [Brumpt, C. R. Soc. Biol., v. bo, 1906, pp. 160-162.]
495 TRYPANOSOMES AND THE TRYPANOSOMIASES
[Trypanosoma barbahila (Leger,i 1904). — This trypanosome is rather
short and relatively stumpy. Its total length is 30 /^ to 40 yu ; width, 4 fn,
to 6 /x ; free flagellum, 11 /i to 12 /i. The undulating membrane is broad,
and presents deep folds. The host is Cohitis barbatula, loach, which
harbours also a new trypanoplasm.]
[Trypanosoma saccobranchi (Castellani and Willey,^ 1905)' — This try-
panosome was discovered in a member of the Siluridas, Saccobranchus
fossilis, in Colombo. The discoverers give few details of morphology ;
they merely state that the centrosome was very near the posterior end.
The degree of infection in these fish varied very much. Endo-corpuscular
parasites were not found in association with the trypanosomes.]
[Trypanosomes in Nile Fish. — Neave^ found trypanosomes in
several species of Nile fish. The parasite of the noke (Mugil) had
the following dimensions : Length, 50 /x ; width, 4 ju ; free flagellum,
12 yu; diameter of nucleus, 4 fx ; distance of centrosome from tip, 5 /i.
Neave states that this fish is a species of grey mullet, and has a gizzard.]
[The trypanosome of the bagara (Bageus bayard) had the following
dimensions: Average length, 51 /* to 58 /x ; width, 5 /i ; free flagellum,
8 fj. ; diameter of nucleus, 3 /* ; distance of centrosome from end, o'2 /i.]
[The trypanosome of the gargur (Lynodontis schal) measured as
follows : Length, 24 /t to 43 /i ; width, 2'5 /i to 4 /u. ; free flagellum, 8 fi.
to 10 ju. ; nucleus, 2/^x3 /x ; distance of centrosome from tip, 0'5 fi.
From Neave's figures it appears that this is a more slender-looking
parasite than the first two.]
[Trypanosomes were also found in the dabib (PolypUrus) when the
blood was examined fresh on three occasions, but ISIeave was unable to
secure a stained specimen of the trypanosome.]
Section 4. — Description of the Trypanosomes of Fishes
belongring" to the Genus Iryxtanoplasma.
We have already pointed out the characteristics of this genus
(p. 26), so shall not refer to them again here.*
[Recent observations show that many species of fish harbour
trypanoplasms. Brumpt is of opinion that the trypanoplasms found
by him in several fresh-water fish are distinct species. Keysselitz,
on the other hand, thinks that all the trypanoplasms seen by him in
the fishes mentioned on p. 483 belong to one species, Tpl. borreli.']
Trypanosoma borreli, Laveranand Mesnil, 1901. — This parasite
was found in the blood of half the number of red-eye {Scardinius
'[_Leuciscus] erythrophthalmus) caught in the ponds in Garches. Young
fish are less frequently infected than those 15 to 17 centimetres
long. In all the red - eye we examined, whether naturally or
artificially infected, the trypanoplasm was scanty in the blood, a
prolonged examination often being necessary to find the parasite.
In fresh blood Tpl. borreli is very active, so that it is impossible
1 [Ldger, C. R. Soc. Biol., v. 57, 1904, pp. 344-347]-
2 [Castellani and Willey, Quart. Journ. Micr. Science, v. 49, 1905, p. 383-402.]
5 [Neave, Second Report of the Wellcome Research Laboratory, Khartoum, igo6,
P- I97-]
* We have pointed out previously (p. 22, note i) how we were induced to modify
our earlier descriptions of the structure of the trypanoplasms.
TRYPANOSOMES OF FISHES
497
to see any details of its structure. One can only see that it often
changes its shape ; sometimes it takes the form of the letter C, with
the undulating membrane along the outer side of the curve ; at other
times it becomes straightened out like an amoeba, when the body
becomes as transparent as the undulating membrane. When the
parasite moves, it travels with the larger end foremost. Neither
nucleus nor granules of any kind are to be seen in the protoplasm.
Stained specimens show that the structure is different from that
of the trypanosomes. The body of Tpl. borreli is flattened and often
curved, as shown in Fig. 74, /, and Fig. i5 of the coloured plate.
The inner (concave) side of the body is thicker than the outer
(convex) side, which merges into the undulating membrane without
any sharp line of demarcation. The outer side of the body stains
less deeply than the inner, but the protoplasm stains uniformly,
Fig. 74. — T RYPA NOPLA SMA EORRELI.
I and 2. Trypanoplasm of the red-eye. 3 and 4. Dividing forms. 5. Trypanoplasm of
the minnow. (Magnified about 1,800 diameters.)
except for some dark granules which are occasionally present. In
some parasites the posterior end stains a dark blue, while the
anterior end is very pale. The posterior extremity may terminate
abruptly, or it may taper off, extending for some distance along the
flagellum.
The body of the parasite undergoes frequent changes of shape as
the result of amoeboid movements, so that the form shown in Fig. 74,
I, although the most common, is by no means always seen. The
form shown in Fig. 74, 2, is fairly common, and sometimes the body
of the parasite is even straighter, so that it comes to be more or less
regularly oval. The length of the body, flagella excluded, is
usually about 20 m, while the width varies from 3 /x to 4 /m or more.
In well-stained preparations there are seen, at the junction of the
anterior and middle thirds of the body, two masses of chromatin,
which are usually elongated with their long axes in the direction of
the long axis of the body. Of these two chromatic masses, the one
situated as a rule on the convex or outer side of the parasite is the
32
498 TRYPANOSOMES AND THE TRYPANOSOMIASES
nucleus (Fig. 74, /, n). It is larger and more oval in form, and
stains less deeply than the other. The smaller of these two masses,
which is usually situated in the concavity of the body, is more
elongated and thinner than the other, and stains a deeper purple
than the nucleus ; it represents the centrosome (Fig. 74, /, c).
The centrosome gives rise to two flagella^ : an anterior flagellum,
which at once becomes free (fa); and a posterior flagellum (fp),
which winds round the anterior extremity of the body, borders the
whole length of the undulating membrane, and finally becomes free
at the posterior end of the body. Sometimes it may become de-
tached from the body before reaching the posterior end, as is shown
in Fig. 74, J and 5. The free part of each flagellum measures
about 15 i".
We have seen some dividing forms in the blood of red-eye
experimentally infected ; the centrosome divides first, then the
flagella divide (Fig. 74, j and 4).
L^ger has often seen trypanoplasms very closely resembling
Tpl. borreli in the blood of minnows (Phoxinus Icsvis, Agass.) in
Dauphin6. In some minnows the parasites are very numerous, and
give rise to profound anaemia. The infected fish remains motion-
less, refuses to feed, and finally dies.^
In form and size the trypanoplasm described by Leger is closely
allied to Tpl. borreli of the red-eye, but there are certain differences
between them. In the minnow the parasites are more regular in
shape than in the red-eye ; secondly, the former parasites often show
large chromatic granules (Fig. 74, 5), and even pigment granules
(L6ger), which are not found in Tpl. borreli ; and, lastly, the trypano-
plasm of the red-eye appears to be less pathogenic than that of the
minnow.
[As the result of inoculation experiments, Laveran^ agrees with
Leger's view that the trypanoplasm of the minnow is the same
species as Tpl. borreli of the red-eye. Of four minnows injected
intraperitoneally with the trypanoplasm of the red-eye, two became
infected, and the trypanoplasm of the minnow similarly infected a
red-eye.]
[Our knowledge of the trypanoplasms of fishes has been con-
siderably extended by the very thorough observations of Keysselitz
published early in igo6.* The following facts have been taken from
the author's long paper on the subject.]
[The infection in the carp, tench, and bream often presents a
certain periodicity, especially a seasonal one, the infection being
1 [Both L6ger and Keysselitz state, however, that the flagella arise from a well-
marked granule — the diplosome — which lies very close to the centrosome.]
^ L^ger, Acad, des Sciences, March 28 and April 4, 1904.
3 [Laveran, C. R. Soc. Biol., v. 57, 1904, pp. 250, 251.]
* [Keysselitz, Arch. f. Protisten., v. 7, 1906, pp. 1-74 ; abstract by Mesnil in
Bull. Inst. Past., v. 4, 1906, pp. 297-300, from which the account given in the text
is largely taken.]
TRYPANOSOMES OF FISHES 499
more intense in the hot weather.^ It is found also that a latent or
mild infection may develop into a severe one after the fish has laid
its eggs. Keysselitz goes fully into the question of relapses and
their causation. He succeeded only once in transmitting the infec-
tion from one fish to another by injection, and he consequently
regards the so-called successful inoculation results of other investi-
gators as instances of a relapse rather than a fresh infection.]
[As previously described by Leger, Keysselitz found a certain
percentage of the infected fish succumb to the infection. The
most important symptom is anaemia, which is evidenced by the
pallor of the gills. Post-mortem one finds serous fluid in the peri-
toneum, hydropericardium, and cedema of the organs.]
[Keysselitz gives a detailed account of the morphology of the
trypanoplasm, and of its' evolution in the intestine of a leech,
Piscicola geometra (this will be referred to again in Section 6).
According to this author, the life cycle and evolution of Trypano-
plasma are very complex, and analogous to those of T. noctuce and
Htzmamaha or Spirochceta ziemanni of the owl (see pp. 42-44), as
originally described by Schaudinn.]
[The blepharoplast (centrosome) contains both true chromatin
and plastin or nuclear substance — a fact which is in favour of its
nuclear origin. In successfully stained specimens eight peripheral
chromosomes could be seen grouped around a central body.]
[The nucleus, says Keysselitz, consists of a central karyosome
and of eight small chromatic granules, which are often joined to the
central body (karyosome) by very slender filaments. In certain
cases, as in heavily infected fishes which are very anaemic, the
granules of nuclear material are more or less scattered throughout
the protoplasm.]
[The nucleus divides by ' pseudo-mitosis.' The karyosome
elongates and becomes dumb-bell-shaped, a fine thread uniting the
two resulting karyosomes ; each chromosome divides into two, and
eventually two nuclei are formed.]
[In addition to the ordinary or 'indifferent' forms of the parasite,
Keysselitz describes two kinds of large forms, which he regards as
sexual elements and calls gametes. The most characteristic differ-
ence between these two sexual forms is the presence of a well-
developed blepharoplast (centrosome) and a relatively small nucleus
in the male gametes, and a relatively large nucleus and small centro-
some in the female gametes. When blood containing these sexual
forms is swallowed by the appropriate leech, conjugation, followed
by further evolution, occurs (see Section 6).]
Trypanoplasma cyprini, M. Plehn, 1903.^ — Miss Flehn found
' [Brumpt thinks that this is due, at least under natural conditions, to fresh
bites of leeches, in which the digestion of the blood and the evolution of the flagel-
lates occur very quickly in hot weather.]
2 M. Plehn, Arch. f. Proiiste?i., v. 3, 1903, p. 175.— Hofer, ' Handbuch der
Fischkrankheiten,' and Allgemeine Fischerei Zeitung, 1904, No. 3, p. 48..
32—2
500 TRYPANOSOMES AND THE TRYPANOSOMIASES
this parasite in the blood of carp obtained from various sources, at
the piscicultural station in Munich. In some cases the parasites
were very numerous, and the infected fish could be recognised by
the pallor of their gills.
According to Hofer, this disease was prevalent in certain ponds
in Germany in which carp-breeding was practised. The sick fish
would remain for weeks on their side, the body bent in the form of
an arc. When touched they would swim a few strokes and then
resume their original attitude. Hofer's assertions as to the cause of
the epizootics of the carp (1900-1902) must be accepted with some
reserve, since Tpl. cyprini was only described in 1903.
The parasite is fairly resistant, for it remains motile for several
days in preparations of blood mixed with salt solution. When its
movements slow down the flagella and undulating membrane can be
distinguished. The latter begins at the anterior end, and does not
quite reach the posterior end of the body. Contrary to what is
found in Tpl. borreli, the flagella are of unequal length ; the anterior
is more than half as long as the body, while the posterior is only a
quarter the length of the body. The posterior flagellum is slender
and very difficult to stain.
The body, which is flattened and lamelliform, twists and folds
itself into all shapes, much like a piece of cloth that is shaken about
in water. The protoplasm contains only a few fine granules. The
body measures from 20 /j. to 25 /*, but may be as little as 10 /x or as
much as 30 fj, long.
Miss Plehn found that intra vitam staining with methylene blue
stained the flagella well, but left the nucleus unstained. Dried films
stained by the Romanowsky-Ziemann method show two chromatic
masses near the anterior end of each trypanoplasm. One of these
masses, the nucleus, is irregularly spherical, stains red, and contains
a number of granules which stain more intensely than the rest of the
nucleus. The other chromatic mass, which is rod-shaped and close
to the edge of the parasite, stains a deep purple, and gives rise to the
two flagella.^ Miss Plehn questions the centrosomic nature of this
mass of chromatin, but does not give any definite interpretation of it.
By Romanowsky's method the posterior flagellum does not stain.
In blood-films treated for two hours with gold chloride, and then
exposed to the sun for four hours in formic acid (Apathy's method),
the chromatic mass from which the flagella arise — and which we
regard as the centrosome — is alone stained black. With other
trypanosomes the same staining reaction is obtained in the corre-
sponding chromatic masses (personal communication from Miss
Plehn).
Chalachnikov had previously seen this trypanoplasm ; some of the figures given by
this author {op. cit.) leave no doubt upon the point.
1 We would here thank Miss Plehn for a letter which she sent to one of us on
March 26, 1904, correcting her earlier description of Tpl. cyprini.
TRYPANOSOMES OF FISHES 501
Multiplication forms are rarely seen. In a film which Miss Plehn
kifidly sent us we found several parasites evidently undergoing
division, as they showed two nuclei and two centrosomes.
[The recently described trypanoplasms include the following :
Trypanoplasma varium (Leger,i 1904). — Length of body about 25 /t ;
of free flagella, 18 /* to 20 /*. This trypanoplasm is allied to Tpl. horreli,
but its flagella are a little longer, and it does not possess the well-marked
cytoplasmic granules seen in the latter form. Unlike Tpl. hovreli, it
presents giant forms, which are amoeboid or vermiform in appearance.
Moreover, Leger found that in certain streams containing both loach and
minnows only the former were infected with this parasite. From this
fact he concludes that Tpl. varium and Tpl. borreli are distinct species. The
host of this trypanoplasm is Colitis barbatula, loach, which harbours also a
trypanosome, T. harhatitlw.]
[Trypanoplasma guernei (Brumpt,^ 1905). — Total length, 54 ^u, ; anterior
flagellum, 16 /i ; posterior flagellum, 4 /*. The centrosome is 9 /x long,
the nucleus 7 jj.. The protoplasm always contains black pigment. The
host is Coitus gohio.']
[Trypanoplasma harhi (Brumpt, 1905). — In the fresh condition the
body alone measures 26 /*. In stained specimens the parasite assumes
the irregular forms described by Leger in Tpl. varium. The anterior
flagellum measures 18 /x, the posterior 9 /x. The centrosome is 11 /x long,
the nucleus 10 ^. The cytoplasm never contains pigment granules.
This parasite occurs in the barbel, Barbus fluviatilisi]
[Trypanoplasma abramidis (Brumpt, 1905). — This trypanoplasm, parasitic
in the bream, was seen only in the fresh condition. Its body measures
30 /t, the anterior flagellum about 15 /*, the posterior 5 /* to 6 /x.]
[Trypanoplasma trutta (Brumpt, 1905). — Like the foregoing, this
trypanoplasm was seen only in the fresh state. It is a small species, the
body measuring only 20 fx, the anterior flagellum 12 /x, and the posterior
flagellum about 4 /x. The host is Salmo fario, trout.]
[Trypanoplasma intestinalis (Leger,^ 1905). — This trypanoplasm,
the first to be described as occurring outside the blood, was found
by Leger in the oesophagus and anterior part of the stomach of a
salt-water fish (Box boops). The body is 14 /x long, the anterior and
posterior flagella each 16 /x. L6ger describes, in addition to these
typical forms, globular forms with three anterior flagella and a
rudimentary undulating membrane. These, he thinks, are female
forms, for he witnessed all stages of their penetration by typical
forms (males).]
[Trypanoplasma ventricuti (Keysselitz,* 1906).— In the paper on
Tpl. borreli already referred to, Keysselitz incidentally mentions,
and gives figures of, this new trypanoplasm, which he found in the
stomach and adjacent part of the intestine of Cyclopterus lumpuSjhom
Bergen, Norway. In appearance this parasite closely resembles the
blood trypanoplasms ; it has two well-developed flagella, each of
1 [Ldger, C. R. Soc. Biol., v. 57, 1904, pp. 344-347.]
2 [Brumpt, Rev. Scieiztif., September g, 1905, pp. 321-332 ; abstract by Mesnil,
Bull. Inst. Past., v. 3, igoj, p. 920; also C. R. Soc. Biol., v. 60, 1906, pp. 162-164.]
3 [Ldger, C. R. Soc. Biol, v. 58, 1905, pp. 511-513 ; abstract by Mesnil, Bull.
Inst. Past., 3, 1905, p. 448.]
* [Keysselitz, Arch.f. Protisten., v. 7, igo6, p. 37.]
502 TRYPANOSOMES AND THE TRYPANOSOMIASES
which takes origin in a distinct granule (diplosome) situated in front
of the blepharoplast. The latter was frequently divided into two.]
Section 5.— Mode of Multiplication of the Trypanosomes of
Fishes.
There is very little information to be obtained upon this point in
the works and papers hitherto published.^ Danilewsky states that
the trypanosomes of fishes multiply by unequal binary division, the
young forms looking like monads.^ According to Chalachnikov, the
young trypanosomes of fishes multiply by longitudinal fission. He
also states that he saw in the blood of Cyprinus carpio and of Esox
lucius, kept for several days in vitro, protoplasmic masses undergoing
division, which he regarded as multiplication forms of the trypano-
somes.^
The trypanosomes are, as a rule, very scanty in the blood of
fishes, and this partly accounts for the difficulty experienced in
finding dividing forms. It may also be due in part to the fact that
these forms are only found at the beginning of the infection, as in
the case of T. lewisi. In order, therefore, to obtain fish under
favourable conditions for examining multiplication forms, we inocu-
lated fishes experimentally by means of intraperitoneal injections of
infective blood from fish of the same species. These experiments,
which we made with the pike, eel, and red-eye, enabled us to study
the most important phases in the multiplication of T. remaki and
Tpl. borreli.
In our experiments we found that the trypanosomes multiply by
equal or subequal binary fission, like T. brucei, for example.* We
have already mentioned the various stages met with in the repro-
duction of T. remaki and Tpl. borreli, so there is no occasion to refer
to them again.
Section 6.— Modes of Infection.
We have seen in previous chapters that the mammalian trypano-
somes are, as a rule, conveyed by biting flies. It is probable that
the trypanosomes of fishes are conveyed by ectoparasites, which
attach themselves either to the gills of the fish or to the surface of
the body between the scales. We have often found small leeches on
the bodies of soles, rays, and red-eye— fish which are frequently
infected with trypanosomes or other hgematozoa.^
' [Keysselitz's paper on Tpl. borreli gives many details of the multiplication of
this parasite, both in infected fish and in the stomach of the leech. Ldger and
Brumpt also describe the evolutionary changes of trypanosomes and trypanoplasms
in various species of leech.]
2 Biol. Centralbl., v. 5, November i, 1885.
' ' Rech. sur les parasites du sang,' Charkov, 1888.
■* Laveran and Mesnil, ' Sur le mode de multiplication des trypanosomes des
poissons,' Acad, des Sciences, June 16, 1902, and Arch.f. Protisten., v. i, 1902.
^ We have described haemogregarines in the sole and ray (Laveran and Mesnil,
Acad, des Sciences, October 14, 1901, and October 13, 1902).
TRYPANOSOMES OF FISHES 503
Leydig long ago found trypanosomes in the ingested blood of
leeches caught on fish. From this it follows that leeches are
probably concerned in the transmission of these parasites.
Keysselitz, in Munich, succeeded in infecting various fishes by
means of leeches taken from fishes of the same species (tench, carp,
and pike) infected with trypanosomes.^
Van Beneden and Hesse have described, under the name of
Hemibdella soUce^ the leech which is frequently found on the' bodies
of soles, particularly at Roscoff.
According to Leger, leeches serve to propagate the trypanosome
of the minnow (private communication).
The following experiments show that it is easy to inoculate the
trypanosomes of a fish into another fish of the same species by
injecting it intraperitoneally with a little infective blood.
Experiment I. — On April 15, 1902, a pike weighing about 500 grammes
was killed, and its blood, which contained trypanosomes in very small
numbers, was mixed with citrated salt solution and injected, in doses of
\ CO. of the mixture, into the peritoneal cavity of two young pike (15 and
12 centimetres long). These pike had been kept under observation for
several months prior to injection, but trypanosomes had never been
found in their blood. The results of the injection were as follows :
Pihe A (15 centimetres long) : April 23, eight days after inoculation,
trypanosomes absent ; May 3, trypanosomes present, but scanty ; May 11,
trypanosomes more numerous. From May 20 onwards the trypanosomes
diminished in number, and on June 4 only one was found after a long
search. The fish survived, and trypanosomes were still present in July,
igo2. Pi}ie B (11 centimetres long) : May 2, seventeen days after inocula-
tion, very few trypanosomes seen in blood ; May 7, trypanosomes more
numerous, as many as five being seen in one field with a magnification of
480 diameters; May 13, fish killed; fewer trypanosomes present. The
trypanosomes were not more numerous in the vessels of the kidneys or
spleen than in the blood taken from the heart or from the periphery.
Experiment II. — An eel, which had never shown any trypanosomes,
was injected intraperitoneally with infective blood from another eel.
Twelve days later trypanosomes were found in the blood of the injected eel.
Experiment III. — On May 8, 1902, the blood of a red-eye containing
a few Tpl. horyeli was inoculated intraperitoneally into five other red-eye
(two medium-sized and three small). In each case the dose injected was
about \ c.c. blood considerably diluted with citrated salt solution. The
five red-eye were carefully examined for trypanosomes before the inocula-
tion,, but with negative results. On May 16 the blood of two fishes was
examined; trypanoplasms absent. From May 21 to 26, three of the
fishes showed trypanoplasms in small numbers ; negative in the case of
the other two fishes. On May 29 two of the fishes — those in which the
blood examination was negative — were found dead (one small and one
medium-sized). The trypanoplasms were scanty in the other three red-
eye. The two small ones were killed ; the parasites were scanty in the
spleen and kidneys, as well as in the peripheral blood. In the case of the
medium-sized red-eye which survived, the blood was examined during the
early days of June, and showed very few parasites.
1 Hofer, op. cit.
2 'Rech. sur las Bdellodes,' Mini. Acad. Sciences Belgique, v. 34, p. 41.
504 TRYPANOSOMES AND THE TRYPANOSOMIASES
This experiment with the trypanoplasm of the red-eye has been
repeated several times, with similar results, the parasites appearing in
the blood of inoculated fishes at the end of fifteen to twenty days,
increasing in number for the next ten or twelve days, and then
diminishing more or less rapidly. In no case has the blood of the
inoculated fishes shown very many parasites, nor has death ever
resulted from the direct effects of the presence of these hsematozoa.
Miss Plehn has succeeded in producing similar artificial infections
in the carp. Of seven carp inoculated into the heart with blood con
taining trypanoplasms, five were infected at the end of two to three
weeks, but in each case the infection was a mild one.
Inoculations from one species of fish into another have hitherto
given uniformly negative results. This fact justifies the description
of different species of trypanosome for the different species of iish,
although the parasites themselves do not present any marked mor-
phological differences.
[The recent interesting observations of L^ger, of Brumpt, and of
Keysselitz prove that various species of leech act as the alternate
host of the trypanosomes and trypanoplasms of fishes, and that in all
probability leeches play an important, if not the sole, part in the
transmission of the infection from one fish to another.]
[Leger^ examined the intestinal contents of leeches (Piscicola sp.)
which had sucked the blood of loaches infected with T. barbatulce.
Eighteen hours after the meal of blood he found pyriform bodies
without flagellum and with one nucleus, or with two unequal nuclei,
which arose from the first by heteropolar division. Later on there
were trypanosomes resembling the ' male,' ' female,' and ' indifferent '
types of Schaudinn. The last multiplied actively by equal binary
fission ; the others, which were larger, multiplied by very unequal
binary fission, and finally the intestine of the leech contained many
very small trypanosomes.] .
[Leeches {Hemiclepsis marginata) which had fed upon the blood
of loaches infected only with trypanoplasms {Tpl. varium) contained
at the end of several days numerous small elongated trypanoplasms,
some of which lacked the anterior flagellum.]
[Brumpt^ states that the trypanosomes of fresh-water fishes
undergo their evolution in leeches of the genus Hemiclepsis. That
of the trypanoplasms is said to occur, according to the species of
trypanoplasm, in Hemiclepsis or in Piscicola. For instance, the
trypanoplasms of the loach and of the barbel, which are morpho-
logically very closely allied, undergo their evolutionary cycle, the
first exclusively in Hemiclepsis, the second exclusively in Piscicola.']
1 [L^ger, C. R. Soc. Biol., v. 57, .1904, p. 344 ; abstract by Mesnil, Bull. Inst.
Past., V. 3, 1905, p. 18.]
^ [Brumpt, C. R. Soc. Biol., v. 57, 1904, pp. 165-167 ; ibid., v. 60, 1906, pp. 160-
162 ; and v. 61, 1906, pp. 77-79 ; abstract by Mesnil, Bull. Inst. Past., vols. 2
and 4.]
TRYPANOSOMES OF FISHES 505
[According to their mode of evolution in Hemiclepsis, the fish
trypanosomes may, according to Brumpt, be spHt up into several
groups : (i) Those which undergo evolution solely in the stomach of
the leech, and never pass into the intestine or into the sheath of the
proboscis. Such are T. abramis, T. remaki, T. bavhi, T. perccB,
T. squalii, and T. acerince. (2) Those in which development starts in
the stomach and goes on in the intestine ; finally the trypanosomes
get into the sheath of the proboscis. This is the mode of evolution
of T. granulosum. (3) Those in which development occurs in the
stomach, and after a certain time the trypanosomes reach the sheath
of the proboscis, as with T. danilewskyi and T. phoxini. In the case
of T. harbatulce, T. langeroni, T. scardinii, and T. leucisci, the complete
evolutionary cycle was not studied owing to lack of material.]
[Brumpt describes fully the evolution of T. granulosum of the eel
as it occurs in Hemiclepsis. Some hours after ingestion the trypano-
somes in the leech's stomach become pyriform, and have the centro-
some near, or in front of, the nucleus, as in Crithidia. They multiply
actively in the stomach, and at the end of forty-eight hours have
nearly all passed out into the intestine. Here they become very
elongated and assume Herpetomonas-iorms, which they retain for
several months. These give rise to trypanosome forms, which reach
the sheath of the proboscis as early as the fifth day after the meal of
infective blood. It is these forms which are inoculated into the eels,
and by simple elongation assume the typical form of T. granulosum.
The complete evolutionary cycle as just described occurs only in
Hemiclepsis ; in other leeches, such as Callobdella punctata, Hirudo
troctina, and Piscicola geometra, the parasites undergo certain evo-
lutionary changes and then die off after a variable time. From
Brumpt's observations it appears that the infection is never con-
veyed to the embryo leeches, and Keysselitz has come to the same
conclusion.]
[Brumpt succeeded in infecting healthy fish by allowing them to
be pricked by infected leeches.]-^
[Two young carp and two river bull-heads, free from parasites, were
infected simultaneously with trypanosomes and trypanoplasms by the
bites of embryo Hemiclepsis and Piscicola, themselves heavily infected. The
incubation period was ten to seventeen days.]
[Of eleven uninfected eels which were allowed to be pricked by
embryos of Hemiclepsis, ten showed trypanosomes in the blood in less than
six days. The eleventh eel did not become infected, owing to the removal
of the part pricked, the pectoral fin.]
[One Coitus huhalis, pricked by Callobdella punctata, also became
infected.]
[The evolution of the trypanosomes of salt-water fishes is a little
peculiar. In the leech's stomach the parasites lose their flagella and
1 [Brumpt, C. R. Soc. Biol., v. 61, 1906, pp. 77-79 ; abstract by Mesnil, Bull.
Inst. Past., V. 4, igo5.]
5o6 TRYPANOSOMES AND THE TRYPANOSOMIASES
divide a certain number of times in this condition ; after some days
flagellated forms again develop. T. solece and T. cotti develop
exclusively in the stomach of Callobciella punctata, and never pass
into the sheath of the proboscis. T. scyllii and T. rajce develop at
first in the stomach of Pontobdella, and then pass into the intestine,
where they have flagella and divide a great number of times.]
[The different species of Trypanoplasma develop, according to
Brumpt, in different leeches : Tpl. guernei, like Tpl. borreli of the
red-eye and minnow, evolutes in Piscicola ; so also does Tpl. barbi.
On the other hand, Tpl. abramidis undergoes its development ex-
clusively in Heiiiiclepsis, and never passes into the sheath of the
proboscis. Tpl. truttce does not develop in Heiniclepsis or Hirudo ; it
probably does in Piscicola.^
[The most detailed account we possess of the development of the
trypanoplasms in leeches is that of Keysselitz in the paper on
T. borreli previously mentioned. According to this author, the
trypanoplasms of the various fishes studied by him all undergo their
evolution in one species of leech, Piscicola geometra.']
[When blood containing the gametes described on p. 499 is
swallowed by this leech, the sexual forms conjugate. There is
fusion of the two cytoplasms, followed by that of the respective
nuclei, the true nuclei uniting after at least one reduction process.
There results from this fusion an ovoid mass, without flagellum,
resembling the ookinetes of the endocorpuscular hasmatozoa or of
T. lewisi (Prowazek ; see p. 89). Two chromatic masses can be dis-
tinguished in this oval parasite : a compact mass which arises from
the union of the two blepharoplasts, and a granular one which arises
from the fusion of the two reduced nuclei.]
[These ookinetes, or ' copulas,' soon give rise to typical trypano-
plasms, of which there are three kinds. On the analogy of those
described by Schaudinn in T. noctucB, these three kinds are called
' male,' ' female,' and ' indifferent.' As in the case of the gametes
(see p. 499), the chief difference is in the size of the nuclei.]
[From this time onward there is an abundant multiplication of
the parasite in the intestinal contents of the leech, and different
forms are seen. Some are very thin (Keysselitz calls them spiro-
chastiform), yet they have all the characteristics of trypanoplasms;
others are short and stumpy. The latter are to be correlated with
the thick consistency of the contents of the leech's intestine, for as
soon as these contents become thinner, as after a fresh meal, the
parasites assume the normal shape, and it is in this form that they
are inoculated into fishes.]
[The multiplication of the stumpy forms was followed with great
care — it is by equal or unequal binary longitudinal fission. In
certain favourable cases a system of longitudinal fibrils or myonemes,
like those described by Schaudinn in T. noctuce, was seen. Lastly,
Keysselitz observed in certain trypanoplasms in the leech some-
TRYPANOSOMES OF FISHES 507
what complicated nuclear changes, which he regards as evidence of
parthenogenesis.]
[The infected leeches may present morbid phenomena which
coincide at times with the period of intense multiplication of the
trypanoplasm. The most obvious sign is marked swelling of the
body from the clitellar region backwards ; in addition to this, there
is an alteration in the colour of the body, the animal becomes less
and less active, and finally dies.]
[Unlike other investigators, Keysselitz failed to produce experi-
mental infection in fishes by means of infected leeches.]
[Keysselitz thinks that other leeches besides Piscicola can sub-
serve the development of Trypanoplasma. In experiments, which he
had not concluded at the time of writing the paper, he observed the
initial stages of evolution in Hirudo medicinalis.~\
[Finally, it may be added that Keysselitz is of opinion that all
the hitherto described trypanoplasms parasitic in the blood of fishes
belong to one species, which should be known as Trypanoplasma
borreli, Laveran and Mesnil.]
CHAPTER XVIII
THE TSETSE-FLIES AND THEIR TRYPANOSOMES
Part 1.— The Trypanosomes of Tsetse-Flies.
[Flagellates (trypanosomes) have been found in the gut of 'native'
or freshly caught tsetse-flies. This is an important fact in view of
the statements of Gray and Tulloch, and of Koch, that ingested
mammalian trypanosomes (T. gambiense and T. brucei) undergo
developmental (? sexual) changes in tsetse-flies.]
[Novy^ has studied these fly trypanosomes in the intestinal con-
tents of specimens of Glossina palpalis sent to him from Uganda.
From a review of the recorded observations of Koch,^ and of Gray
and Tulloch,^ as well as from his own cultivation and other
experiments, Novy concludes that the trypanosomes met with in
the tsetse-flies are harmless non-parasitic flagellates corresponding
to the equally harmless Herpetomonas and Crithidia observed by him
in mosquitoes.* He bases this view upon the following facts : (i) The
large size of the tsetse-fly parasites compared with the blood-forms ;
(2) their presence in flies which had not been fed experimentally on
infected animals ; (3) the failure to obtain any development of the
1 \J>iovy, Journ. Infect. Dis., v. 3, 1906, pp. 394-411; abstract by Mesnil in
Bull. Inst. Past., v. 4, 1906, p. 606.]
2 [Koch, Deutsche med. Wochenschr.., November 28, 1905, pp. 1865-1869.]
^ [Gray and Tulloch, Sleeping Sickness Commission Report, No. 6, 1905,
pp. 282-287.]
* [In a recent paper upon the 'Trypanosomes of Mosquitoes and other Insects'
(Jx>urn. Inf. Dis., v. 4, No. 2, April, 1907, pp. 223-276), Novy, McNeal, and Torrey
maintain their earlier view (see p. 38) that ' the mosquito flagellates are not stages
of intracellular organisms, but are probably parasites peculiar to the insects.'
These observers have given the name Trypa7iosoma culicis to a flagellate found in
several specimens of Culex, and they state that the parasite found by the Sergents
in the gut of a larva oi Anopheles maculifennis (see p. 37) closely resembled their
flagellate. They state, further, that the flagellates of mosquitoes belong to two
easily differentiated types, Crithidia and Herpetomonas j and that these two types
are common in other insects, and should be placed under the trypanosomes,
instead of being classed as distinct genera.]
[They give the name T. chrisiophersi to a trypanosome found by Christophers
in the gut of a dog-tick, Rhipicephalus sanguineus, in Madras. The flagellates
seen were typical cultural forms ; total length, 30,11 to 45 11, including free flagellum
8 /i to 12 /i. There is a prominent undulating membrane, extending over about
half the length of the body. The nucleus is situated about the middle of the body;
the centrosome is close to, and on one side of, the nucleus, but sometimes it lies
immediately in front of it. This trypanosome is not a developmental phase of
Piroplasma canis, and we have no proof at present that piroplasms pass through
a trypanosome stage in their life-cycle.]
508
THE TSETSE-FLIES AND THEIR TRYPANOSOMES 509
trypanosomes ingested by flies fed on infected animals ; (4) the failure
to infect susceptible animals with the flagellates of the tsetse-fly;
and (5) analogy with the flagellates (trypanosomes) of mosquitoes.]
Several varieties of trypanosome were present in these flies, and
Novy thinks there may be several species. He gives the name
Trypanosoma grayi to the numerous forms seen in one of the flies.
These very varied forms come under two types, just as Novy had
found in the case of T. avium of birds. Type i (see Fig. 75, a) is thin
and very elongated (body 18 /* to 29 /^ long, by 0"6 /* to i /i wide), with
a long free flagellum, so that the total length may be 36 /i to 48 [i.
The nucleus is rod-shaped, very deeply stained, and compact ; the
centrosome is large, deeply stained, quite round, and immediately
anterior to the nucleus. In this type, as well as in the other types
Fig. 75. — Trypanosomes of the Tsetse-fly (T. grayi).
a. Male form with compressed nucleus and long free flagellum. b and c. Female forms,
posterior extremity thickened, short free flagellum. In a later publication (Nature,
November 15, igo6), Minchin calls c an ' indifferent ' form. d. Young form resulting
from the unequal division of a large female form, a, b, and c are from the gut of
the tsetse-fly (Gl. falpalis) dissected ten days after having fed on an uninfected
monkey, d is from the gut of a fly twenty-four hours after its first feed of blood.
(After Minchin, Gray, and TuUoch. Magnified about 2,000 diameters.)
of tsetse -fly trypanosomes, there is, says Novy, a more or less
marked diplosome situated near the nucleus, usually between it and
the centrosome. It may be mentioned that a diplosome has also
been described in some of the Herpetomonas.~\
[Type 2 (see Fig. 75, b, c) is a wide and long ribbon-like form,
with a short free flagellum and a well-developed undulating mem-
brane. The nucleus is rounded (about 2 /* in diameter), and the
centrosome is usually just in front of the nucleus, but may be lateral
or even posterior to it. Novy compares these two types to the
' male ' and ' female ' types respectively of T. gambiense described by
Koch in Gl. palpalis.']
[As Gray and Tulloch had shown, division is very unequal (see
Fig. 75, d) in these trypanosomes, and usually takes place in the
ordinary way, starting in the centrosome.]
510 TRYPANOSOMES AND THE TRYPANOSOMIASES
[The preparations from the other tsetse-flies showed forms differ-
ing from the preceding and from one another, although evidently of
the same generic group. Novy distinguishes three types, one of
which he says might possibly be regarded as having some relation to
T. gambiense (see Fig. 76).]
[Minchin, Gray, and Tulloch^ have studied, in Uganda, the
Gl. palpalis in its relation to T. gambiense and other trypanosomes.
They confirm Novy's observations upon these trypanosomes of the
tsetse-fly, and Minchin has given the name Trypanosoma tullochii^ to
the type which Novy says is most like the human trypanosome.
r. tullochi (Fig. 76, a, b, c) is distinguished by its more rounded nucleus,
situated near the middle of the body, and by its small, usually
circular, centrosome, situated well behind the nucleus.]
Fig. 76. — Trypanosomes of the Tsetse-Fly (T. tullochi).
a. Large form, with minute circular centrosome, from the gut of a fly. b. Large form,
from the proventriculus of the same fly. c. Dividing form, common type, from
the gut of the same fiy. (After Minchin, Gray, and Tulloch. Magnified, 2,000
diameters.)
[Tsetse-flies known to contain T. grayi or T. tullochi, or both, were
fed on various animals — fifteen monkeys, two guinea-pigs, one white
rat, and two hens — but in no case did these animals become infected
by the bites of the fly. As we have seen, however, in the chapter on
Human Trypanosomiasis, Bruce, Nabarro, and Greig succeeded in
infecting monkeys with T. gambiense by zWovfing freshly caught tsetse-
flies to feed upon them.]
[An interesting observation of Minchin, Gray, and Tulloch seems to
show that goat serum has a remarkable effect upon T. grayi, and not upon
T. gambiense. A large number of freshly caught tsetse-flies were fed on a
native goat, and on dissecting these flies (some 500 in number) not a
single one was found to contain trypanosomes. Other flies, caught at the
same time and place, fed on the other experimental animals (monkeys,
1 [Minchin, Gray, and Tulloch, Proc. Roy. Soc, Series B, v. 78, 1906, pp. 242-
258 (with 3 plates) ; reprinted in Report of Sleeping Sickness Commission of the
Royal Society, No. 8, 1907, pp. 122-136.]
2 [In conformity with the rules of nomenclature followed by Laveran and Mesnil
and adopted throughout this volume, I propose to amend the name given by
Minchin, and to call this trypanosome Trypanosoma tullochi. — Ed.]
THE TSETSE-FLIES 5TI
etc.), were found to contain trypanosomes in the usual proportion. Pre-
parations were then made of goat serum and T. grayi, and of the same
goat's serum and T. gamhiense. It was found that in the preparation of
T. grayi the trypanosomes were rapidly immobilized and died off, while
the T. gamhiense remained active. Similar preparations made with human
serum instead of with goat serum showed that the trypanosomes were
unaffected in either case. This result seems to furnish an additional
means of distinguishing between T. gamhiense and T. grayi.]
[Minchini has recently described a stage of encystment of T. grayi in
the proctodaeum of Gl. palpalis. The undulating membrane disappears,
so that the parasite comes to resemble the genera Herpetonionas and
Crithidia ; the flagellum becomes gradually shorter, and appears to
become retracted into a pink-staining vacuole (see Fig. 9), reminding one
of the flagellar vacuole described by Leishman during the formation of the
flagellum in cultures of the Leishman body. A pink-staining cap, which
is formed at the hinder pole, gradually extends round the parasite, and in
this way an irregularly-circular cyst, containing a darkly stained centro-
some and a somewhat fragmentary nucleus, is produced.]
[The other parts of the gut of this fly contained normal trypanosomes —
very few differentiated sexual forms, but many indifferent forms, which
gave rise to young forms and ultimately to the small Herpetomonas-Yi\i.&
forms found in the proctodaeum. Owing to lack of nutriment here these
forms, it is suggested by Minchin, became encysted.]
[These cysts closely resemble the ' schleim-cysten ' described by
Prowazek^ in Herpetomonas musca-domestica, and, as in the case of the
house-fly, they are no doubt destined to pass out of the fly's gut with its
dejecta. The house-fly, being a foul feeder, becomes infected with the
Herpetomonas by swallowing these cysts with its food. Not so, however,
the tsetse-fly, which is very particular about its food. Minchin suggests
that these cysts are destined to be swallowed accidentally by some verte-
brate, the — as yet unknown — host of T. grayi, in order to germinate in its
digestive tract, to pass thence into the blood, and to be taken up again
with the blood by the tsetse-fly. Minchin proposes to call this type of
infection — which has been proved by Schaudinn to occur in the case of
Amceha coli infection — the contaminative type. In the other mode of infec-
tion, which Minchin calls the inoculative, the parasite, after going through
developmental changes in the insect, passes back again into a second verte-
brate host through the proboscis, as in the case of malaria transmitted by
a mosquito.]
Part 2.— The Tsetse-Flies.
The study of the African trypanosomiases is intimately connected
with that of the tsetse-flies. In the chapter on Nagana and Human
Trypanosomiasis we have quoted the experiments of Bruce, Nabarro,
and Greig, showing the role of the tsetse-fly in the propagation of
these diseases. A volume like the present one, dealing with the
trypanosomiases, ought, therefore, to include an account of the
morphology, biology, and taxonomy of the genus Glossina. We
have taken these from Austen's monograph,^ which gives a compre-
hensive account of the tsetse-flies, as well as a full bibliography.
^ [Minchin, Froc. Roy. Sac, Series B, v. 79, 1906 ; reprinted in Sleeping Sick-
ness Commission Report, No. 8, 1907, p. 137-142.]
^ [Prowazek, Arb. a. d. kaiserl. Gesund., v. 20. 1904, p. 446].
^ E. E. Austen, ' A Monograph of the Tsetse-Flies (genus Glossina, Westwood),
based on the Collection in the British Museum, with a Chapter on the Mouth-
Parts, by H. J. Hansen, London, 1903.
512 TRYPANOSOMES AND THE TRYPANOSOMIASES
For a long time the name tsetse-fly was synonymous with one
well-known species, Glossina morsitans, Westwood. It was this
tsetse-fly which was suspected of playing the principal part in the
propagation of nagana, and the attention of explorers was naturally
drawn to this particular fly on account of the personal annoyance it
produced, and loss of animals to which it gave rise. Later on, how-
ever, other species of the same genus, with habits similar to those of
Gl. morsitans, were discovered, and writers have not always dis-
criminated between these species of tsetse-fly. Thus, the name
' tsetse-fly ' is now used to include all the species (Austen recognises
eight)^ of the genus Glossina.
We shall first consider the genus Glossina as a whole, for it is
highly probable that Gl. morsitans is not the only species concerned
B C
Fig. 77. — Glossina morsitans- (After Bruce.)
A. Resting condition, with the wings completely overlapping. B. Fly with the wings
extended ( x 2J). C. Anterior part of fly seen in profile.
in the propagation of nagana and the other African animal trypano-
somiases. Moreover, it has been proved that it is another species —
Gl. palpalis — which conveys the parasite of human trypanosomiasis.
The tsetse-flies are not very large in size, being a little larger
than the ordinary house-fly (Musca domestica), and decidedly larger
than Stomoxys calcitrans. Their appearance does not bear out their
terrible reputation.
A tsetse-fly, when at rest, can be at once recognised by the wings,
which almost completely overlap like the blades of a pair of scissors
(see Fig. jj, a). In other flies which resemble the tsetse more or
less closely [Stomoxys, Hcematopota) and, like it, suck blood greedily,
the wings are always separated a certain distance when the flies are
at rest. The proboscis of the tsetse projects horizontally in a line
with the axis of the body (Fig. jj, c). This is also the case in
Stomoxys, but in the latter the palpi do not ensheath the proboscis,
as they do in Glossina, so that the proboscis appears thinner. The
male tsetse is easily distinguished from the female by the external
^ [The original gives the number as seven, but, as has been stated on p. 120,
footnote 3, Austen now recognises Gl. tachinoides as a distinct species.]
THE TSETSE-FLIES 513
genital organ, which forms a well-marked protuberance (hypopygium)
on the ventral surface of the abdomen near the distal end. The
females have no hypopygium.
The tsetse-fly is usually found in low-lying, hot, moist regions,
such as the banks of rivers and lakes, and never occurs far from
water. It is found in the vicinity of dense undergrowth or in forests —
never in open plains. It appears to have a predilection for the shade
of certain trees or shrubs, such as the mimosa, as noted by Chapman
in South Africa, and by Morel on the Shari. Occasionally it is met
with on hills, as, for example, in North Transvaal. In North
Rhodesia the tsetse has been found 4,110 feet above the level of the
sea. [In Uganda, which is about 4,000 feet above sea-level, tsetse-
flies abound along the shores of the Victoria Nyanza and on all the
islands in the lake. The tsetse-fly, Gl. palpalis, has also been found
recently on both shores (Congo Free State and Uganda) of the
Albert Nyanza, about 2,400 feet above the sea.]
In the so-called ' fly belts' the tsetse is not necessarily universal.
Fig. 78. — Glossina morsitans. (After Bruce.)
A. Fasting fly. B. Fly with its abdomen distended witli blood after a feed. ( x 2i.)
It is often strictly localized to small areas which are thickly wooded,
or where there is dense undergrowth, the intervening areas being
quite free. Or a region may be infested with the tsetse except in
glades or clear spaces, where it is never met with. It is, therefore,
possible to travel with animals through such an infested region by
travelling at night and spending the day in these glades. Some-
times the fly is found on one bank of a river and not on the other,
as Livingstone described in the case of the River Chobe.
The fly bites most furiously during the day, less so in the evening,
and only very rarely at night, when the moon is shining brightly.
Both sexes are blood-sucking.
' On entering " fly country," ' says Bruce, ' one is not long left
in ignorance of the presence of the tsetse. The natives may be seen
slapping their naked legs, the dogs bite round, and the horses kick.'
In places covered with dense undergrowth one may be attacked by
thirty or forty flies in the space of a few minutes.
The fasting tsetse ' has a direct flight, flopping, if I may use the
term, suddenly on the animal attacked ' (Bruce), and, as the fly likes
shade and hides itself under leaves, amongst the hairs of animals,
and in the folds of the skin, it is not easily seen, but the effects of its
bite quickly reveal its presence.
33
514 TRYPANOSOMES AND THE TRYPANOSOMIASES
' The fly makes a loud buzzing sound when flying, but after its
feed and at rest it emits a peculiar sharp, shrill note, probably caused
by an action of the wings ' (Bruce).
The fly alights on the skin so gently that one does not feel it.
According to Foa, the insertion of the proboscis is painless ; Bruce
says it is less painful that in the case of the mosquito ; while others
compare it to the sting of the bee or wasp. Occasionally, in as short
a time as twenty or thirty seconds, the fly fills itself with blood (see
Fig. 78, A and B), and the abdomen becomes first pink and then dark
red. "When the fly withdraws its proboscis after feeding, slight
irritation at the place punctured is usually experienced.
A tsetse gorged with blood is lethargic and can be easily caught.
As a rule, the fly quickly goes back to the undergrowth, where it hides
and digests its meal in peace.
That the tsetse follows the big game is the unanimous opinion of
explorers, travellers, and sportsmen who have been in Central and
South Africa. There may be game without tsetse, says Theiler, but
there is no tsetse without big game. The latter appears, however,
not to be true in the case of British East Africa and Uganda, where
tsetse-flies are found in the absence of big game ; but before attempt-
ing to explain this fact further observations upon this point are
necessary to show conclusively that such is really the case. If true,
it may be explained, for example, by the Survival of the flies during
a dry season which has caused all the big game to migrate from its
ordinary haunts, or by the fact that the British East African species,
to which the observation refers, are different from those found in
South and Central Africa — Gl. morsitmts, etc.
Unlike most of its allies, the tsetse avoids the excretions of
animals, so that animals whose bodies are covered with a layer
of excrement are thereby protected from the bites of the fly (Living-
stone). As soon as one begins to disembowel an antelope covered
with tsetse-flies the latter disappear (Foa).
Mode of Reproduction. — We are indebted to Bruce for a de-
tailed account of the mode of reproduction of the tsetse. The tsetse-
flies — or at least some of them — belong to ' the group of parasitic flies
which, on account of their peculiar mode of reproduction, have been
termed Pupipara ' (Austen).^ They extrude a yellowish larva, which
is almost as large as the abdomen of the mother. The larva in the
species studied by Bruce (according to Austen, this was not Glossina
morsitans, but the closely allied species Gl. pallidipes, or possibly
both) is about 6J millimetres long, by about 3^ millimetres wide. It
is annulated and consists of twelve segments. ' Immediately on being
born the larva creeps about actively, evidently searching for some
cover or hole in which to hide. Having found a resting-place, it
1 [Of these the best known are the mammal and bird parasites belonging to
the family Hippoboscida: (Austen, op. cit., p. 24).]
THE TSETSE-FLIES 515
immediately begins to change colour, and after a few hours has
turned into a jet-black hard pupa.' (For details of structure, see
Fig. 79.)
' If these pupal cases are kept in a perfectly dry place, the perfect
insect hatches out in about six weeks. ... It has often been sur-
mised that this ily is bred in buffalo-dung, but from a consideration
of the foregoing facts it is evident that nothing is wanted except any
moderately dry place ' (Bruce).
[It has been mentioned (see p. 413) that in Uganda Bagshawe
has found that the natural habitat of the pupa of Gl. palpalis is the
loose soil around the roots of banana-trees along the lake-shores.]
It is very probable that all the species of Glossina are pupiparous.
Fig. 79. — Pupa of Zdluland Tsetse-Fly. (After Austen.)
A. Dorsal aspect ( x 8). B. Anterior extremity, showing bifurcated longitudinal seam
which opens to permit the escape of the imago (x5j). C. Posterior extremity,
showing pit and right larval stigma s ( x i6).
but this has not yet been definitely established in the case of some
species.
[The pupa of Gl. palpalis varies in length from 5^ millimetres to
6i milHmetres, and in greatest width from 3 to 3^ millimetres. In
general appearance it closely resembles that of the Zululand tsetse
(see Fig. 79), but on closer examination slight differences are dis-
cernible. ' The tumid lips on the last segment are much closer
together in the pupa of Gl. palpalis than in the Zululand tsetse, the
space between them being reduced by quite one half, while the lips
themselves are somewhat larger, and covered with sparser, and
therefore more conspicuous, granules' (Austen). Other minor points
of difference are present, and Austen expresses the opinion that, did
we but know them, all the species of tsetse -flies might be dis-
tinguished in the pupal stage by the characters of the last segment.]
[Amongst the recent publications upon the habits, anatomy, etc.,
of the tsetse-fly may be mentioned those of Austen,^ ' Supplementary
^ [Austen, Brii. Med. Journ., September 17, 1904.]
33—2
5i6 TRYPANOSOMES AND THE TRYPANOSOMIASES
Notes on the Tsetse-Flies,' from which the above account of the pupa
of Gl.palpalis is taken ; of Giles/ ' Anatomy of Stomoxys and Glossina ';
of Stephens and Newstead,^ ' The Anatomy of the Proboscis of Biting
Flies '; of Minchin,^ ' The Anatomy of the Tsetse-Fly {Gl. palpalis) ';
of Sander/ ' Die Tsetsen '; of Koch/ and of Button, Todd, and
Newstead.]"
The tsetse-fly appears to be limited to tropical Africa.'^ It is
found between 13° N. Lat. — in Senegambia, on the Shari, and
possibly, if James Bruce really saw the tsetse, on the confines of
the Sudan and Abyssinia — and 26° S. Lat. Austen's map shows
it to be particularly prevalent in the river-basins of East Africa,
but that is because the fly is better known in these regions, to which
the attention of explorers and sportsmen has been particularly drawn,
especially the basin of the Zambesi. Nevertheless, recent accounts
appear to show that the fly is no less prevalent in the river-basins of
West Africa.
[Many of the recent observations on the" distribution of the tsetse-
flies in various parts of Africa have already been referred to (see
especially Chapters VI. and XII.). Amongst others, the following
publications may be mentioned : that of Laveran,^ on ' Sleeping
Sickness ' and ' The Distribution of the Tsetse-Flies in Various Parts
of French West Africa and the Congo Free State ' — species of
Glossina were obtained from Senegal, French Guinea, French
Sudan, French Congo, and the Congo Free State ; of Major Smith,^
on the occurrence of Gl. palpalis in Sierra Leone ; of Balfour and
Neave,^" on the distribution of Gl. inorsitans and Gl. palpalis in the
Anglo - Egyptian Sudan, and the occurrence of the former as far
north as 12° N. Lat., in South Kordofan ; of Nabarro,^^ Greig, and
the later members of the Sleeping Sickness Commission, on the
distribution of tsetse-flies, especially Gl. palpalis, in Uganda and
1 [G. M. GWes, Journ. Trap. Med., v. 9, 1906.]
2 [Stephens and Newstead, Liverpool School of Tropical Medicine, Mem. 18,
1906, pp. S3-74-]
' [Minchin, Proc. Roy. Soc, Series B, v. 76, 1905, pp. 531-547 ; reprinted in
Sleeping Sickjiess Commissio7i Report, No. 8, 1907, p. 106.]
■• [Sander, Arch.f. Scliiffs u. Tropenhyg., v. 9, 1905, pp. 193, 254, 309, 355.]
'■> [Koch, Deutsche med. Woclienschr., No. 47, November 23, 1905.]
" [Dutton, Todd, and Newstead, in the Annals of Trop. Med. and Parasitology,
Liverpool, v. i, No. i, 1907, pp. 54-75.]
' [Captain Carter {Brit. Med. Journ., November 17, igo5, p. 1393) records the
capture of tsetse-flies in South Arabia on October 10, 1903. The fly has been
identified by Newstead as Gl. tachinoides, and Carter states that it ' does not
depend for its existence on the big game, for, excepting gazelle, nothing else
frequents the belts of bush which it haunts.]
[Carter's observation is very interesting, because it disproves the belief that the
tsetse-fly does not occur beyond the African continent.]
^ [Laveran, C. R. Soc. Biol., v. 59, 1905, p. 332; C. R. Acad. Sciences, v. 139,
1904, p. 658 ; V. 140, 1905, p. 75 ; V. 141, 1905, p. 929.]
" [Smith, R.A.M.C.Joiirn., v. 5, 1905, p. 692.]
'" [Balfour and Neave, Second Report of the Wellcome Research Labor., Khar-
toum, 1906, pp. 29-32, with a map; see also Brit. Med. Jotcrn., June 17, 1905.]
11 [Nabarro, Greig, etc., Sleeping Sickness Commission Reports, Nos. 5, 6,
and 8, 1905-1907.]
THE TSETSE-FLIES
517
the East Africa Protectorate ; of Austen/ on ' The Distribution of
the Tsetse-Fhes '; of Button, Todd, and Newstead,^ on the wide
distribution of tsetse - flies in the Congo Free State, and the
description of a supposed new species, which Newstead calls Gl.
maatlata ; of Carlos Franga,^ on a ' New Species of Glossina from
Fig. 80. External Mouth Parts and Pharynx of Glossina morsitans. (After
Hansen, in Austen.)
l.i. Labium (inferior), h. Hypopharynx. l.s. Labium superior, or labrura. f. Basal
part of left maxillary palpus, b. First segment of the labium (bulb of the proboscis).
p.h. Pharynx.
Cazengo, Angola, to the North of the River Coan^a '; of Wellman,*
on ' Trypanosomiasis in Angola,' and the description of a new
subspecies of Gl. palpalis ; and of Yale Massey,^ on the occurrence
Fig. 81. — Gloss/xa palpalis. (After Austen.)
of sleeping sickness and of Gl. palpalis on the Lualaba River,
Central Africa.]
[Lastly, reference has already been made to the interesting fact
that tsetse-flies {Gl. tachinoides) have been found in South Arabia.]
The genus Glossina was created in 1830 by Wiedemann for his
species Gl. longipalpis. It belongs to the order Diptera, or two-
1 [Austen, Sleeping Sickness Commission Report^ No. 6, 1905, pp. 278-282, with
map.]
'^ [Dutton, Todd, and Newstead, op. cit., 1907, pp. 54-75, with map.]
2 [C. Yraxiqa., Jornal de Sciencias Math., Phys., e Naluraes, 2nd Series, v. 7,
No. 27, Lisbon, 1905, pp. 134-136.]
* [Wellman, Journ. of Hyg., v. 6, part iii., 1906, pp. 237-245 ; and Annals and
Magazine of Natural History, September, 1906, pp. 242-244.]
s [Yale Massey, Lancet, August 4, 1906, p. 296, and March 30, 1907, p. 908.]
5i8 TRYPANOSOMES AND THE TRYPANOSOMIASES
winged flies, and is a member of the family Muscidis (used in the
narrower sense), which comprises the genera Beccariinyia, Stoinoxys,
Hcematobia, Lyperosia, and Glossina, all of which are blood-sucking
insects. By the venation of its wings, the ramification of the hairs
of the arista,''- the bulb at the root of the proboscis, the conformation
of the male genital apparatus, and, lastly, by its pupiparity, the
genus Glossinz occupies a unique position among this group of
insects.
Austen gives {op. cit., p. 60) the following diagnosis of the genus :
Glossina, Wiedemann, 1830 { = Nemorhina, Robineau-Desvoidy,
1830). — Narrow - bodied, elongate, dark greyish - brown or yellowish-
brown, dull-coloured flies, ranging in size front 7^ millimetres^ in the
case of a small specimen of Gl. morsitans, Westw., to 12 millimetres
in that of a large female of Gl. fusca. Walk. ; recognisable when
alive and at rest by the wings being closed flat one over the other above
the abdomen (beyond which they project considerably), instead of divaricate
(as in the case of Stomoxys), or tectiform (as in Hsematopota), and by
the proboscis (i.e., proboscis ensheathed in the palpi), which in length is
equal to the thorax without the scntellum, projecting horizontally in front
of the head; palpi, as seen in the natural position, extending slightly
beyond the proboscis, their inner sides grooved so as to form a sheath for
the latter, to which in life they are applied so closely as entirely to conceal
it ; base of proboscis suddenly expanded beneath into a large onion-shaped
bidb. (For details of the proboscis, see Fig. 80.)
The dichotomous table^ (see p. 521), borrowed from Austen,
enables one to distinguish easily between the eight species of the
genus, except perhaps between Gl. longipalpis and Gl. morsitans.^
[The recently described new spe'cies (?) and subspecies are the
following : Gl. decorsei (Brumpt), Gl. bocagei (Franga), Gl. maculata
(Newstead), and Gl. palpalis wellmani (Austen).]
Glossina decorsei. — In 1904 Brumpt^ described, under the name of
Gl. decorsei, a species of tsetse caught by Decorse in the Shari basin
and on the shores of Lake Tchad. It is a small fly, the males measuring
7'33 millimetres and the females 8-27 millimetres in length. The colour
of the abdomen is like that of Gl. morsitans : the median dorsal longitudinal
band is well marked, dull yellow in colour, broad on the second segment,
but getting gradually narrower on the third, fourth, and fifth segments,
and only a narrow line on the sixth segment. The transverse interrupted
stripes are very dark in colour and occupy the anterior four-fifths of each
^ The appendix to the terminal segment of the antennse. This is the only
visible part of the antennae in the difif'erent figures of Glossina reproduced here.
■^ [Length measured from the face to the end of the abdomen, excluding the
proboscis and wings (Austen).]
^ [The table given in the original has been amplified so as to include the
eighth species (Gl. tachinoides) now recognised by Austen, as well as a few minor
details which he gives in his ' Revised Synopsis of the Species of Glossina' in the
'Supplementary Notes on the Tsetse-Flies' (Brii. Med. Journ., September 17,
1904), previously quoted.]
* Austen says that the most characteristic distinguishing features between these
two species are furnished by the hypopygium in the male. (See table on p. 521.)
^ Brumpt, C. R. Sac. Biol., April 16, 1904, p. 628.
THE TSETSE-FLIES 519
segment, so that the extreme hind margin of each segment is pale or
cinereous, and crosses the median longitudinal band at right angles.
There are circular black patches on the second abdominal segment. The
hind tarsi are black, which makes this new species allied to Gl. palpalis.
Indeed, specimens caught by Decorse and presenting the above char-
acteristics were examined by Austen, who stated that these flies were
undoubtedly Gl. palpalis var. tachinoides, Westwood. (Letters of April 8
and. 13, 1904.)
[Since then, however, Austen has had the opportunity of examining
many more specimens of this fiy, and has come to the conclusion that
Gl. tachinoides, Westwood, is a distinct species. Moreover, ' an examination
of some of Decorse's specimens shows,' says Austen, ' that the supposed
new species {Gl. decovsei) is in reality none other than Gl. tachinoides. West-
wood.']
[Glossina hocagei. — The following is the description given by Fran9ai of
this supposed, new species, which came from Cazengo, Angola. Length
of body, 8'5 millimetres; of specimens filled with blood, 11 millimetres.
Length of wing, 8 millimetres ; wing-expanse, 19 millimetres. Thorax, grey,
the anterior segment lighter, with brown spots. Abdomen brown, with a
longitudinal yellowish line well marked in the second, third, and fourth
segments ; less marked in the fifth, and hardly visible in the sixth and
seventh segments. The posterior borders of the abdominal segments are
not pale. The legs are amber-coloured, except the hind tarsi and the last
two joints of the middle pair. There are no dark patches on the anterior
tarsus. The third joint of the antennae is uniformly yellowish ; the second
joint is brown.]
[Austen has examined the typical example of Gl. bocagei, Fran§a, and,
after comparing it with the type of his Gl. palpalis wellmani, he has come to
the conclusion that Gl. bocagei is merely a synonym of Gl. palpalis wellmani.
(Letter of September 25, 1906.)]
[Glossina maciilata (Newstead).^ — This is the name given by Newstead to
a fly (a somewhat imperfect specimen of a female) caught at Ghumbiri, on
the Congo River. His original description is here reproduced.]
[' General Appearance. — Very dark brown ; posterior surface of head
cinereous, spotted with black ; thorax dark brown and faintly cinereous
in places, with elongated transverse black spots ; pleurae, coxae, and
femora cinereous, with conspicuous black spots.; first and second segments
of hind tarsi black. (The remaining segments wanting.)]
['Female. — Head with the frontal stripe rich ochreous brown; frontal
margins and ocellar spot bright yellowish-white to pale ochreous ; ocelli
black ; posterior surface of head cinereous, with large well-defined irregular
Hack: spots. Antennce dull red-brown in front, sides with a cinereous
surface ; arista dull reddish-brown. Palpi blackish above, paler beneath.
Bulb of proboscis dark castaneous, shining. Thorax dark brown and
cinereous, with numerous irregular elongated black spots placed trans-
versely ; anterior angles pale brown. The scutellum spotted hke the
thorax, margin pale brown ; pleura cinereous and pale brown, with
numerous irregular and more or less confluent black spots. Abdomen
very dark brown ; the narrow basal segment cinereous, with numerous
black spots ; the broad second segment, with the large median area, the
anterior angle, and broad hind margin, cinereous with black spots ; the
remaining segments, with the exception of the last, with a narrow well-
defined median stripe, and hind margins narrowly cinereous ; lateral
margins of segments three to five, with a cinereous triangular patch ; the
hind margins with an occasional more or less obscure black spot, with
the exception of the sixth, which has a regular series of ten or eleven on
1 [Franga, see footnote ', p. 517.]
2 [Newstead, Annals of Trnp. Med. and Parasit., Liverpool, v. i, 1907, p. 73.]
520 TRYPANOSOMES AND THE TRYPANOSOMIASES
the grey cinereous band ; last segment darker than the rest, with a lateral
greyish spot, in the centre of which is a small black one. Legs : All the
coxae cinereous and pale reddish-brown, with numerous more or less con-
fluent black spots ; hind femora, with the basal third and apex, pale red-
brown, the rest faintly cinereous, with a few large, faint, dull brown
blotches ; anterior and hind tibiae pale brown, mid tibiee slightly darker,
with, in some lights, faint indications of dark spots ; anterior tarsi and first
segment of the mid pale brown; first and second segment of the hind
tarsi dark brown. (The remaining segments of the hind and mid tarsi are
wanting.) Wings uniformly brown.]
[' Length, exclusive of proboscis and with the abdomen somewhat
curved, 9 millimetres ; length of wing, 9 millimetres.']
[Newstead states that ' this species may be readily recognised from the
other species of the genus by the curious spotted or mottled appearance of
the thorax, pleurae, and femora. To the naked eye it looks like a dark
specimen of Gl. palpalis, but a pocket lens immediately reveals the peculiar
markings.']
[It is possible that this supposed species, of which only a single
specimen has hitherto been obtained, may eventually prove to be merely
a variety of Gl. palpalis, or, at the most, to be entitled to subspecific rank.]
[Gl. palpalis wellmani, Austen.^ — This subspecies of Gl. palpalis
was found by Weilman at Esupua, on the lower reaches of the River
Katumbela, Angola. It has also been found by Massey on the
Upper Congo, and we have already seen that Gl. bocagei, Franga,
from the River Coanza, Angola, is regarded by Austen as identical
with this subspecies of Gl. palpalis.]
[' The new subspecies may be characterized shortly as follows by
indicating the points in which it differs from the typical form :
[' Gl. palpalis wellmani (suhsp.n., J' ? ). — Frontal stripe pale ochra-
ceous ; thoracic markings much reduced, so that the thorax in a well-
preserved specimen appears spotted, the antero-lateral markings taking
the form of spots or blotches ; the spot immediately behind the inner
extremity of the humeral callus on each side small, ovoid, or nearly
circular, and especially conspicuous when the insect is viewed from
above and slightly from behind ; femora pale, the dark blotches
much reduced' (Austen).]
[Austen adds that the specimens caught by Weilman ' are of
especial interest as being the first recorded examples of any form of
Gl. palpalis from Portuguese \'\'est Africa, and as showing that the range
of the species in question, which has recently been stated by Laveran^ to
occur at Sengaleam (about thirty miles from Cape Verde), extends at least
as far south as 12° 30' S. Lat. In all probability Gl. palpalis wellmani will
eventually be proved to exist right down to the Cunene River, the southern
boundary of Angola, if not further ; and it is to be hoped that evidence to
decide the southern limit of Gl. palpalis will shortly be forthcoming. ']3
1 [Weilman, y(3a?-;z. Hyg., v. 6, 1906, pp. 237-245 ; also Annals and Magazine
of Natural History, September, 1906, pp. 242-244. Also Austen, ibid.. Series 7,
V. 15, April, 1905, p. 390.]
2 [Laveran, C. R. Acad. Sciences, v. 139, 1904, p. 659.]
^ [Austen, Annals and Magazijie of Natural History, v. 15, April, 1905.]
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.8
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fl alpis, 116, 199. 228, 52r
longipeJinis, 115, 166, 167, 201, 408,
52X
maculata, 517
description, 519
morsitans, 116, 156, 166-7, ^92, 199,
228, 364, 406, 521
description, 512
pallicera, 521
pallidipes, 167, 192, 205, 408, 514, 521
palpalis, 204, 208-9, 228, 244, 361, 369,
406, 508, 512-3, 515, 517, 321
in human T-sis, 407
pupa of, 515
welbnani, 362, 408, 519
description, 520
tachinoides, 117, 120, 199, 228, 517, 521
Goat, caderas, 301, 306
dourine, 217, 322
galziekte, 345
mbori, 221
nagana, 138, 151, 177
serum, 177
526 TRYPANOSOMES AND THE TRYPANOSOMIASES
Goat, surra, 269, 270, 275, 277
Togo virus, 197
T-sis in, 67, 238, 244
of Abyssinia, 202
of Abyssinian frontier, 207
of Cameroon, 200
of Entebbe, 209
of French Guinea, 227-8
of Uganda, 206
T. dimorpkon, 238, 244
T. gambiense, 382, 389
Goat-sucker, T. in, 439
Gohio fl uviatilis , T. in, 483, 495
gobio, 481
Gobius, 482
giuris, T. in, 483
niger, T. in, 483, 494
Goebel on osmosis, 27
Goldfinch, T. in, 440, 454
American, T. in, 441
T. laveraiii in, 454
Goose and T. avium, 450
Togo virus, 194
nagana in, 140, i8i
Gray and Tulloch's method, 12, 472
Green, brilliant, in treatment, 434
Gudgeon, 481
T. in, 479, 483. 495
Guinea, French, T-ses of, 226
Guinea-pig, atoxyl, treatment with, 421
cadeias, 300, 302
dourine, 341
el debab, 216
galziekte, 345
immunity, 91
mbori, 220
nagana, 131, 149, 151, 421
Soemedang, maladie de, 341
surra, 266-7, 271, 275-6, 280, 422
Togo virus, 197
T-sis of, 105, 216
T. dimorplion, 235
T. gambiense, 382, 387, 421
T, iewisi, 20, 66, 72, 86, 91
T-sis, Abyssinia, 202
Abyssinian frontier, 207
Entebbe, 209
Uganda, 206
Gunnelus vulgaris, 482
H(Emamceba danilewskyi, 448
ziemanni, 43
Hmmatobia, 219
Htsmaiomonas, 33
H(Emaiomonas carassii, 480
cobiiis, 480
HcBmatopinus spinulosus, T. in, 88
HcBmatopota, 290
Hsematozoa, intracorpuscular, of reptiles, 2
HEemocytozoa, 42
Hasmoflagellates, 19
H(£mogregarina bagensis, 475
balfouri, 38
bigeniiha, 494
blanchardl, 494
boihi, 495
callionymi, 494
cotii, 494
Jlesi, 494
gobii, 494
laternm, 494
plaiesses, 493
quad?-igemina, 484
siviondi, 491
splendens, 474
Hsemogregarine in crocodile, 458
in frog, 475
HcBmoproteus da7iilewskyi, 441
majoris, 441
Hismoproteus ziemanni, 441
Halberstaedter's method, 13
Halteridium, 43, 45, 454
noctu(B, 53
Hamster, T. in, 105
Hapale pencillatus, T. gambiense m, 382
Harporhynchus rufus, T. in, 441
Hav/k, T. mesnili in, 441
red-shouldered, T. in, 441
Heat and cold, action of, on trypanosomes,
V. Action of heat and cold
Hedgehog, caderas in, 297
nagana in, 126
T. gambiense, 382, 389
Heidenhain's stain, 11
Helobdella algira, T. in, 474
Hemiclepsis, 495. 505
marginaia, 504
Herpetomonas, 25, 32, 36, 37, 508
algeriense, 37
tombycis, 38
bUtscklii, 99
jaculum, 37, 39
Iewisi, 58
'musc(Z'domestic(Z , 38, 511
subulata, 38
Herpetosonia, 34
Hippobosca, 202, 225, 228, 290
inaculata, 351
rufipes, 350
Hirudo medicinalis, Tpl. in, 507
trociina, T. in, 505
Hii'unao rustica, T. in, 442
Historical account of T., i
survey of the genera, 31
Horse, caderas, 292-311
dourine, 48, 312
galziekte, 345
mbori, 222
nagana, 28, iii, 151, 170
serum, 177
surra, 247-85
Togoland, 193
Togo virus, 197
T-sis in Algeria, 210
Horses, T-sis in Abyssinia, 202
in Abyssinian frontier, 207
in Annam, 286
in Gambia, 229
in Somaliland, 201
T. gambiense, 382, 390
and tsetse-fly, 165
House-martin, T. in, 442
House -sparrow, 442
Human serum in nagana, 177
Human trypanosomiasis, 352
blood-counts in, 376
cerebro-spinal fluid, 399
complications, 381
Congo State measures, 414
description of, 369
diagnosis, 409
duration, 381
Glossina palpalis, 407
fish-eating in, 369
geographical distribution, 359
gland puncture in, 370, 401
historical, 352
influence of age, occupation, race, sex,
366
lumbar puncture in, 399
mode of propagation, 406
pathogenic agent, 398
pathological anatomy, 391
predisposing causes, 366
prognosis, 410
prophylaxis, 411, 413
skin eruptions in, 378
treatment, 411, 433
INDEX
527
Hysena and nagana, 168
Hydrochcsrus capybara, 299, 307
Hyla arborea^ T. in, 462, 469
lateristriga, T. in, 464, 469
viridis, T. in, 461
Icterus galbula^ T. in, 441
Immunity, active, mode of production, 90
if inherited, 90
passive, 93, 96
Immunization, results of passive, 97
Immunizing serum, nagana, 178
Incubation period, nagana, 15
Indian squirrel, T. in, 98
Infection, mode of, in Batrachia, 478
in caderas, 307
in dourine, 337
in fishes, 502
in human trypanosomiasis, 406
in nagana, 165
in surra, 278
natural in rats, 88
Infectivity of trypanosomes, 28
Inoculation experiments, 15, 187
Isolation of trypanosomes, 14
Ixodes tesfudinis, T. of, 457
Jackal and nagana, 169
and T. gambiense, 382, 386
T-sis of Entebbe, 209
Jaclcdaw, 442
Jaculus gordoni, and T-sis of Sudan, 204
orientalis, 266
Jaundice of cattle, 343
Java sparrow, T. ot, 441
Jay, blue, T. in, 441, 454
Jenner's stain, 10
Jerboa, surra, 266
T. gambiense, 382, 389
Jinja disease, 305, 344
Kachuga iectuvi, T. in, 458
Kala-axar, 48, 51
Karyosome, 51
Kinetonucleus, 21
Kingfisher, T. in, 440
Kite, Indian, T. in, 442
Koch's classification of T, diseases, 187
Koodoo, nagana in, 140, 168
Labrus, 482
Lagonosticta min-iina, 450
Lark and T., 446
Laniarius cruentus, T. in, 442
Laveran's staining method, 9
Leech, morbid phenomena, 507
Tpl. in, 499, 504
T. in, 474, 504
Leishman-Donovan body, 10, 48
development of, 49
staining method, 10, 12
Leil^hmania donovani, 51
tropica, 51
Lemur tnongoz and T. gambiense, 382, 3S3
r?ibriventer and T. gambiense, 382
Lepadogaster gouanii, 482
Leptomonas, 36
Lepus cunictilus, T. in, 104
Leuciscus, T. in, 483, 495
cephalus, 481
T. in, 483, 495
eryihropktkalmus , T. in, 483
Tpl. in, 483
idus, T. in, 483
Tpl. in, 483
rutilus, 481
T. in, 483
TpK in, 483
Leticocytozoon ziemanni, 43
Lice, T. Iswisim, 88
Light, action of, after injection of colouring
agents, 419
Limanda platessoides, T. in, 483, 494
Lingard on measurements, 17
Lissojlagellata, 37
Lizards and dourine, 331
T. in, 458
Loach, T. in, 480, 481, 483, 496
Tpl. in, 483, 501
Lophius piscatorius, 482
Lota moiva, 482
vulgaris, T. and Tpl. in, 483
Lote, T. in, 479
Loxia coccothraustes, 439
Lumbar puncture, 399
Lynodoniis sckal, 482, 496
Mabuia raddonii, T. in, 458
Macacus, inoculations, 68
cynomolgus, inoculation, 331
and T, gambiense, 382, 383
rhesus, 129, 236, 382, 383, 417
sinicus, 424
Macrones cavasius, T. in, 483
seenghala, T. in, 481
iengara, T. in, 481
Macronucleus, 20
Mai de caderas, 5, 292
Mai du coit, 5, 312
Mai de la Zuifana, 211
Maladie de Soemedang, 341
Malaria of cattle, 343
Mammals, small, trypanosomes of, 98
Manioc root, 353
Marino's stain, 11
Mariposa pha:nicaiis, 450
Marmoset and T. gambiense, 382
Marmot and T. ga7nbiense, 382, 389
and nagana, 126
Masai donkey, immunity of, 192
Mathis' medium, 14
Mbori, 202, 219
dog, 220
dromedary, 186
guinea-pig, 220
horse, 222
rabbit, 220
rat, 220
sheep, 221
treatment, 222, 416, 423
McNeal's method, culuvations, 13
Measurements, Lingard on, 17
Aleles taxus, T. o', no
Melophagus ovinus, 38
Melospiza fasciata, T. in, 441
Membrane, undulating, 22
Merula Tiierula, T. in, 442
migratoria, T. in, 441
Method for staining, etc., 7
Billet's, 470
Bradford and Plimmer's, 12
Bruce and Nabarro's, 398, 409
Giemsa's solution, lo, 13
modified, 470
Gray and Tulloch's, 12, 472
Halberstaedter's, 13
Heidenhain's, 11
Jenner's, 10
Laveran's, g
Leishman's, 10, 12
McNeal and Novy's, 13
Marino's stain, 11
Mathis' medium, 14
Ross's, 12
Ruge's, 12
Tulloch's, 12
Methylene blue in treatment, 433
Micronucleus, 51
528 TRYPANOSOMES AND THE TRYPANOSOMIASES
Milvus govinda, T. in, 442
Mimosa polyacantha, 120
Minchin's classification, 37
Miniopterus schreibersii^ T. in, 107
Minnow, T. in, 483, 495
Tpl. in, 495. 496
Mole, T. in, i, 58, 109, no
Alonadidea, 37
Monas i-otatoria, frog, 461
Monkey, arsenic treatment, 434
atoxyl treiitment, 421
caderas, 297, 302
dourine, 322, 331
experimental infection, treatment of, 432
Gambia, 236
human T-sis in, 366
nagana, 129
serum, 177
surrn, 266
treatment, 432
T-sis of Abyssinian frontier, 207
of Entebbe, 209
of Sudan, 203
of Uganda, 206
T. gambiense, 358, 382, 421
Morphology of trypanosomes, of agglutinates,
81
of birds, 443
comparative, 16
general, 16
T. brucei, 150
T. duiioni, 100
T. of frog, Hong Kong, 476
T. rotatorium. 471
T. in French Sudan, 225
T. in tsetse-fly, 156
T. vivax, 200
' Morular ' mass, 444
Mosca brava, 307
Mosquito, T. m, 43, 508
Motella musiela, a^^z
tricirraia, 482
Mouse, benzidene dyes in, 426
caderas in, 295, 297, 302-3, 305, 309,
colouring agents, 419
dourine, 322, 327
experimental T-sis, 428, 431
galziekte, 345
mbori, 220, 222
nagana, 123, 125, 132, 151, 173, 428
serum treatment, 174
surra, 265, 275, 431
Togo virus, 197
T-sis, 99, 211, 215, 228
T. divio7'pho7i, 234
T. gambiense, 382, 388
Movement of trypanosomes, 27
Mugil, T. in, 482, 496
Mukebi, 204, 205
Mule, surra in. 247. 252, 279, 280
T-sis in Entebbe, 208
T-ses of Uganda, 204
Mulita, caderas in, 297
Mullus surmuletus, 482
Miis decumanus^ 58, 60, 85, 125
giganteus, 102
minutus, loi
musculus, 60, 99
niveiventery 60
raitus, 58
rufesce/ts, 58, 60
spicatus, 102
sylvaticiis, 58, 67, 123, 132
Musca domestUa, 512
Mustelus canis, 481
Myocyte layer, 27
Myonemes, 24, 27
Myotis murinus, loS, 217
Myoxus avellanarius, T. of, 107
glis, 107
Nagana, 2, 4, 5, in
aetiology, 164
animals susceptible to, 121
Bovidse, 136
cat, 128, 149, 169
cattle, 112, 114. 117
diseases allied to, 185
dog, III, 127, 151, 183
donkey, 151
Equidse, 132
fox, 130
geographical distribution, 113
goat, 133
goose, 181
guinea-pig, 131
hedgehog, 126
historical, in
horse, 28, in, 118, 151
human serum, 176
immunizing serum, 178
incubation period, 15
koodoo, 140, 168
monkey, 129
mouse, 123, 125, 132, 151
experimental, 428-31
pathological anatomy, 140
pig. 15. 13s. 142. 159
prophylaxis, 178
rabbit, 130
rat, 123, 125, 141, 151
serum-therapy, 174
sheep, 112, 138, 151
squirrel. 130
treatment, 169, 417-9, 421-3, 428-31
Narica Jiasua, 299
Necturus maculatus, 463, 477
Negro lethargy, 359
Neophron perciwpterus, 442
Nepa cinerea, 39
Nerophis lumbricoides, 482
Nesokia providens^ 67, 102
giganteus, 102
Newt, T. in, 464, 477
Nicticorax gaj'denia, T. in, 442, 455
Nile fish, T. in, 482
Noke (fish), T. in. 482, 496
Novy and McNeal's method for cultures,
13
Nucleolus, 51
Nucleus, 16, 20
Nuti'ia, 297
Nutrition of trypanosomes, 27
Nyciipithecus felinus, 297
Oicomonadace^, 36
Oicomonas, 36
Ookinete, 42
Opiocephalus siriatus, T. in, 481
Oriole, Baltimore, T. in, 441
Ortkagoriscus mala, 482
Osmosis, Goebel on, 27
Osmotic properties of trypanosomes, 27
Otter, caderas in, 297
Owl, T. in, 439, 440, 443
7". noctuts, 24
Ox, T-sis of Abyssinian frontier, 207
of Entebbe, 209
of Uganda, 206
Padda oryzivora, 448
T. in, 441
Pagellus centrodonius, 482
erythrimis, 482
Pantasiomina, yj
Paradoxurus, 288
Para?na;baeiihardi, 56
INDEX
529
Parammcio'ides, 33, 461
costatus^ 461
Paramcecium costaium, 31, 460
loricatum, 31,460
Passer domesHcus, T. in, 441
and T. avium, 450
Passive immunity, 93
mode of production of, 96
results of, 97
Pelobafes fuscus, 465
Percajluviatilis, 480, 483, 495
Perch, T. in, 479, 483, 495
Periplast, 20
Peste de cadeiras, 292
Petrie, cultivations, 13, 104
Pheasant, T. in, 442
Phoxinus Icsvis, T. in, 483, 495, 496
Tp], in. 489
Phyllomonas, 36
Phytojlagellata, 37
Pig, caderas in, 301
naganain, 15, 135, 142, 159
Togo virus, 197
T-sis of, 213
T. gambiense, 390
Pigeon, dourine, 331, 339
T. in, 440
and T. avium, 450
Pike, experiments on, 503
T. in, 479, 481, 485
T. remaki, in, 21
Pipisirellus pipistrellus^ T. in, 108
Piroplasma canis, 508
oonovani, 51
Piroplasmo5\s, bovine, 343
Piscicola geometra, 499, 504, 505
Pitkecia satanas and / . gambiense, 383
Placobdella ca enigera, 475
Plaice, T. in, 493
Plaiessa microcephala , 48^
vulgaris, 482, 483, 493
Platophrys laterna, T. in, 483, 494
Platyiheca, 36
Pleuronectes, 482
Jlesus, 482, 483, 493
Plimmer's method, 12
Polymastigina, 37
Polyneuritis in'fectiosa equorum, 321
Polypleciruin gerniani, T. in, 442
Polypterus, T. in, 482, 496
Position of the trypanosomes, 35
Posterior chromatic body, 51
' Precipitin' reaction, 190
Precipitinogen, 150
Preservation of trypanosomes, 29
of birds, 444
of fishes, 484
of T. brucei, 156
of T. equimim^ 304
of T. eguiperdum, 334
of T. evansi, 275
of T. gambiense, 404
of T. lewisi, 74
of T. paddce, 449
of T. theiieri, 348
Protomastigina, 36, 37
Protomonadina , 36
Protoplasm of trypanosomes, 19
Pteropus medius, T, of, 108, 109
Pytelia subjlava, 451
Python, T. in, 459
Rabbit, atoxyl treatment, 421
caderas, 292, 302
colouring agents, 419
dourine, 322, 329, 336, 338-g
galziekte, 345
mbori, 220
nagana, 130, 149, 151, 169
Rabbit, Soemedang, maladie de, 341
surra, 255, 266, 267, 271-2, 279
Togo virus, 197
T-sis in, 67, 74, 103, 213, 215, 287
of Entebbe, 209
of Somaliland, 201
of Uganda, 206
T. dimorphon, 235
T. evansi, 422
T. gambiense, 382, 387, 421
Radium, action of, 76, 419
Raja alba, 482, 492
clavaia, 481, ^92
macrorynchus, 481, 492
inicrocellata, 482, 492
mirelatus, 482, 492
mosaica, 481, 492
punctata, 481, 492
Rana angolense, 463, 475
esculenta, 461, 465, 467, 473
temporaria, 462
theileri, 463, 475
trinodis, 468
Rat, caderas, 296, 302, 306, 308
colouring agents, 419
dourine, 322, 327
experimenial infection of, 61
treatment of, 432
galziekte, 345
human T-sis, 366
mbori, 220
nagana, 123, 125, 141, 149, 151, 171
natural modes of infection in, 88
parasite peculiar to, 58. V. also T, lewisi
surra, 266. 271, 276, 280, 281
Togo virus, 197
T-sis in, 2, 3, 7, 8, 14, 25, 58-9, 60, 61-2,
65, 2ir, 215, 287
of Abyssinian frontier, 207
of Cameroon, 199
of Entebbe, 209
of Somaliland, 201
of Uganda, 206
T. brucei, 421
T, dimorphon, 233
T. lewisi, 15, 21, 28, 30, 61, 68, 'j'j^ 88, 94
T. gambiense, 357, 382, 387, 423
treatment, 432
T. vgandense, 357
Rat-louse, T. in. 88
Raven, Indian, T. in, 440
Ray, T. in, 481, 492
Red-eye (fish), T. in, 481, 483, 495, 496
experiments on, 503
Redvvater fever, 343
Reptiles, T. of, 3, 457
Rhipicephalus sanguineus, T, in, 508
Rhizo?7iasHgina, 36
Rhombus lizvis, 483
maximus, 482
River bull-heads, experiments on, 505
T. in, 483
Roach, 481, 483, 495
Robin, T. in, 441
Rockling, T. in, 479
Roller-bird, T. in, 440, 443
Ross's method, 12
Rudd. V. Red-eye
Ruge's method, 12
Ruminants, dourine in, 330, 336
Saccobranchus fossilis, T. in, 483, 496
Salmo fario, T. in, 479
Tpl. in, 483, 501
Scardinius erythrophthalmus, 481, 483, 495, 496
Tpl. in, 495
Schleim-cysien, 511
Sciurus griseimanus, T. in, 130
palmarum, T. of, 103, 106
34
530 TRYPANOSOMES AND THE TRYPANOSOMIASES
Sciurus vulgaris, T. in, 130
ScolephagMS carolintis, T. in, 441
Scomber scomber, 482
Scyllium caniculi, T. in, 481, 492
stellare, T. in, 481, 492
Sections, staining of trypanosomes in, 12
Serinus canarius, 450
meridionaliSj 450
Serum, animal, in nagana, 177
chimpanzee, 177
diagnosis, 189
fowl, 162, 177
frog, 473
goat, 162, 177
in surra, 283
on T, grayi, 510
goose, 162, xjj
horse, 162, 177
human, in nagana, 177
in surra, 283
in treatment, 95, 245
and T. gambiense, 412
of immunized rats, 93
of monkey, 177
of pig, 162, 177
of rat, 162
of sheep, 162, 177
Serums, action of, 417
on T. fiadd(S, 451
Sexual forms of T., 42-44, 88, 156, 348, 403,
509
of Tpl. , 499, 506
Sheep, caderas in, 301, 306
dourine, 336
galziekte, 345
mbori, 221
nagana, 112, 138, 151
?urra, 269
Togo virus, 197
T-ses of Cameroon, 199
Entebbe, 209
Uganda, 206
T. dimorphon, 239
T. gambiense, 382, 389
Shrike, red-breasted, T. in, 442
Sialia sialis, T. in, 441
Sigui t^gu^ (flies), 226
Silurus cla7'ias, T. in, 482, 493
glanis, T. in, 483
Sleeping sickness, 352, 371
Snake, dourine, 331
Sodium arsenite, 95, 169, 245. V. also Arsenic
Soemedang, maladie de, 341
Sole [Solea vulgaris], T. in, 481, 491
Somaliland, T-sis of, 201
Sorex cmruleus, 102
Souma, 115, 186, 202, 205, 223
Soumaya. Same as Souma
Sparrow and dourine, 331
English, T. in, 441
song, T. in, 441
Specific agglutimns, 85
Spermophile, T. of, 106
Spermophilus guttatus, T. of, 106
musivus, T. of, 106
Spinachia vulgaris^ 482
Spinus tristis, T. in, 441
T. laverani in, 454
Spirillum duttoni, 46
ohermeieri, 46
Spirochcsia, 37, 45, 442
evansi, 247
obermeieri, 46
pallida, 47
plicatilis, 47
refriJigens, 46, 47
ziemanni, 44, 454
Spleen extract in treatment, 418
Splenomegaly, tropical, 48
Springbok, nagana in, 139
Squalius cepkalus, 481, 483, 495
Squatina angelus, 482
Squirrel, Indian, T. in, 98, 103, 106
nagana in, 130
Staining methods, 8. V. Method for staining
Starling, 442
Stegomyia fasciata , 37, 107
Sterlet, T. in, 479
Stickleback, 481
Stomoxys, 38, 186, 200, 202, 210, 219, 225
calcih'ans , 279, 307, 512
geniculatus, 253, 280
nebulosa, 307
nigra ^ 279
Sh'epsiceros capensis, nagana in, 140, 168
Strychnine sulphate in sleeping sickness, 435
Sudan, Anglo-Egyptian, T-ses of, 203
French, T-ses of, 219
Surra, 2, 3, 246
aetiology, 278
animals susceptible to, 254
bat, 109, 266
Bovidse, 257, 281
buffalo, 248, 251, 257-8, 281-2
camel, 247, 261, 281
cat, 268
cattle, 247, 279
dog, 254, 258, 261-4, 274, 279, 280
donkey, 256, 279
elephant, 261
Equidse, 246, 257
geographical distribution, 246
goat, 269, 270, 275, 277
guinea-pig, 266-7, 271, 275-6, 280
horse, 247, 249, 250-2, 254-5, 275, 279,
280-1
jerboa, 266
mode of infection, 278
monkey, 266
mouse, 265-6, 275
experimental treatment in, 422-3,
431
mule, 247, 252, 279, 280
pathogenic agent, 272
pathological anatomy, 271
prophylaxis, 282
rabbit, 255, 266-7, 271-2, 279
rat, 266, 271, 276, 280, 281
sheep, 269, 270
treatment, 282, 422-3, 431
vSutoko, 205
Swallow, T. in, 440, 442
Sylvia airicapilla, 440
Syngnathus, 482
Synkaryon, 53
Syphilis, organism of, 47
SyrniuTn aluco, T. in, 439, 444
Tabanidse, 186, 200, 202, 219, 307
Tabanus, ■z'Z^, 228
dorsovitta, 406
glaucopis, 38
lineola, 278
ne7noralis, 219
iergestinus, 38, 39
tomentosus, 219
tropicus, 278
Tackypkormus ornaia, T. in, 442
Tadpole, T. in, 462
Taher (horse disease), 218
Talpa europea, T. of, no
Tatusia hybrida^ 297
Technique, 7
Tench, T. in, 479, 481
Testudo elongata, 289
Therapeutic measures, value of, 425
reactions (chromo), igo
Theropithecus gelada, 201
Thiroux's cultivation, 13, 100
INDEX
531
Thrasher, brown, T. in, 441
Thrush, song, T. in, 442
Thyroid tabloids in treatment, 434
Tibarsa, 246
Tinea tinea, T. in, 480-1, 489
vulgaris, T. in, 483
Tpl. in, 483
Tmerdjin (horse disease), 218
Toad, T. in, 464, 477
Togo virus, 196, 197
Togoland, T-ses of, 193
Torpedo torpedo, 482
Tortoise, Asiatic, T. in, 457
mud, T. in, 457
Traekurus tracliurus, 482
Tragarot in treatment, 434
Tragelaphus scriptus sylvaticiis, 140, 168
Treatment, 415-38
arsenic compounds, 420
arsenious acid, 434
aioxyl, 416, 420, 434-8
attempts at, of T. lewisi infection, 95
benzidene dyes, 415, 426
brilliant green, 434
caderas, 308, 415-6, 422, 431
chrysoidin in, 416
cultures of organisms, 418
dourine, 338, 416, 422, 425
Finsen rays, 419
galziekte, 351
Gambian T-sis, 245
experimental, 431
human T-sis, 411, 433, 434-8
light, 419
mbori, 222, 416, 423
methylene blue, 433
nagana, 169
experimental, 417-9, 421-2, 428-31
radium emanations, 419
serum-therapy, 339
serums, 417. V, Serum
sleeping sickness. V. Human T-sls
spleen extract, 418
strychnine sulphate, 435
surra, 282-3
experimental, 422-3, 431
T. gambiense infections, experimental, 416,
421, 423-5, 432-4
thyroid, 434
tragarot, 434
trypanred, 415, 420, 434
X rays, 76, 159, 419, 434
Treponema pallidum, 46, 337
Treron calva, T. in, 442
Triekogaster faseiatus , T. in, 481
Triehomonas (Donn6), 33
in fowl, 440
intestinalis , 17
Trigla, 482
Trilobus gracilis, 99
Triton vulgaris, 46?
Troglodytes csdon, T. in, 441
Trophonucleus, 20
Trout, T. in, i, 481
Tpl. in, 501
Trutta fario, 481
Trypanomonas , sub-genus, 34
Trypanomorpha, of Woodcock, 26
Trypanophis, 24, 26
Trypanoplasma, 16, 24, 481
abramidis, 490, 501
barbel, in, 495, 501
barbi, 501
Barbus fiuviatilis, in, 483, 501
borreli, 18, 24, 4S3, 496, 506-7
multiplication forms in, 502, 506
Box boops, in, 501
bream, in, 501
carp, in, 499
Trypanoplasma, Cobitis barbatula, in, 501
Cottus gobio, In, 483, 501
Cyclopterus lumpus, in, 501
cyprini, 483, 488, 499
development of, 506
description, 26
evolution of, 499
fishes, of, 496
guernei, description of, 501
intestinalis, 482, 501
leech, in, 499, 504
loach, in, 501
minnow, in, 489, 498
new genus, 35
Phoxinus Imvis, in, 496
Piscicola geometra, in, 499
Salmo fario, in, 4S3, 501
trout, in, 501
irtitics, 501
- varium, 501
ventrieuli, 501
Trypanosoma abramis, 489
Abramis brama, in, 481
Acei-ina cermia, in, 483, 495
vulgaris, in, 480
acerincE, description, 495
African dove, in, 442
description, 455
Agelaius phaniceus, in, 441
American goldfinch, in, 441
Anguilla vulgaris, in, 481, 490
Athene brama, in, 440
noctua, in, 42, 445
avium, 23, 439, 441
canary, in, 450
cultural characteristics, 453
description of, 444
minus, 442
badger, in, no
bagara (fish), in, 482. 496
Bageus bayard, in, 4S2, 496
balbianii, 34
Baltimore oriole, in, 441
bandicoot, in, 67, 102
bandicotti, 102
barbatulm, description, 496
barbel, in, 479, 483, 495
barbi, description, 495
Barbus fiuviatilis, m, 483, 495
bat, in, 107
Batrachia, in, i, 460
belli (n. sp. ), description, 477
birds, of, i, 2, 3, 7, 439
cultivation of, 443
morphology of, 443
relation of, to other blood parasites,
454
Sudan, 455
table of dimensions, 447
blackbird, in, 442
red-winged, in, 441
rusty, in, 441
blackcap warbler, in, 440
blanehardi, description, 107
Blennius pholis, in, 483, 494
bluebird, in, 441
borreli, 458, 464, 469-470
bothi, description, 495
Bothus rhombus, in, 483, 495
boueti, description, 458
bream, in, 481, 489
brill, in, 483, 495
brown thrasher, in, 441
brucei, 14, 17, 18, 19, 20, 24, 25, 38, 74,
112, 121, 147, 167, 199. V. also
under Nagana
agglomeration, 161
atoxyl, 421
attenuation of virus, 181
34—2
532 TRYPANOSOMES AND THE TRYPANOSOMIASES
Trypanosoma brucei, compared with T. evansi,
273
cultures, 159
involution torms, 163
morphology of, 150
multiplication forms, 153
nucleus of, 20, 21
preservation of, 156
staining of, 152
Bufo reticulatus, in, ^464, 477
viridis in, 465
bull-head, river, in, 483
Buteo lineatus, in, 441
callionymi^ description, 494
Callionymtis dracunculus, in, 483, 494
camels, in, 2, 3, 115, 201, 219, 247, 261,
281
ca7'assii, 480
Carassius auraius, in, 488
vulgaris, in, 480, 483
castellanil, 355
cat, in. V. Cat
cazalboui, 118, 225, 227
chafifinch, in, 440, 442
characters of, 25
Chelidon urbica, in, 442
ckrisiopheisi, 508
chub, in, 483, 495
claries, 482
description of, ^93
cobitis, 480
Cobitis barbatula, in, 480, 496
fossilis, in, 480
Colaptus auraius^ in, 441
comparative study of, 16 '
congolense, 116
costaiuin, 463
cotti, description, 494
Cotttts bubalis, in, 483, 495
gobio, in, 483, 495
crane, in, 439
crocodile, in, 459
culicis, 508
cuniculi, 103
Cyanocitta crisiata, in, 441
Cyprinus carpio, in, 48C-1, 483, 488
dabib (fish), in, 482, 496
da?noni(S, description, 457
danilewskyi, 482
description, 488
delagei, description, 494
Diemyctulus viridescens, in, 464, 477
dimorpho7i, 18, 19, 23, 116,118,203,226-7,
229, 240. V. Gambia, T-sis of
horses in
individuality of, 243
dog, in. V. dog
dogfish, in, 481, 492
dogtick, in, 508
donkey, in. V. Ass and Donkey
dormouse, in, 107
dove, mourning, in, 441
dromedary, in, 5, 214, 219
Dryobates villosus, in, 44.1
dnttoni, 20, 99
eberthi, 34, 440
eel, in, 481, 490
egret, in, 442
elegans, of frog, 463
of gudgeon, description, 495
Emberiza citriTiella^ in, 442
Enghsh sparrow, in, 441
Equidse, in, 2, 3, 58, 132, 292
equinum, 19, 21, 292, 303
equiperduin, 15, 152 ■
cultivation of, 335
in dourine, 312, 332
Esox lucius, in, 479, 480-1
Estrelda estreida, in, 445
Trypanosoma evansi, 18, 19, 74, 117, 223, 246,
272
compared with T. brucei, 273
treatment, 422
field-mouse, in, i, 58
fishes, in, i, 2, 3, 7, 25, 27, 28, 33, 479
grouping of, 505
mode of multiplication of, 502
flesz, description, 493
Elesus vulgaris, in, 483, 493
flicker (bird), in, 441
flounder, in, 483, 493
Fringilla ccelebs, in, 442
frog. V. frog and Rana
T. rotatorium of, 20, 21, 28, 31, 465
gambiense, 19, 23, 29, 38, 243, 352, 401.
V. also Human T-sis
and atoxyl, 421
cat, 382
cattle, 391
Cebus capucinus, 382
Cercopithecus fuliginosus, 382
chimpanzee, 382
cow, 382
Cynocepkalus sphinx, 382
description of, 401
dog. 382
donkey, 382, 390
experimental mfections, treatment of,
416, 421, 423-5, 432
goat, 389
guinea-pig, 382
Hapaie pencil laius, 382
hedgehog, 382, 389
horse, 382, 390
jackal, 382
jerboa, 382, 389
Lemur, 382
mongoz, 382
rubriventer, 382
Macacus cynomolgus, 383
rhesus, 383
niarmoset, 382
marmot, 382, 389
monkey, 382
mouse, 382, 388
pathogenicity of, 382
pig. 390
Pithecia satanas, 383
rabbit, 382
rat, 382
sheep, 382, 389
treatment. V. Treatment
gargur (fish), in, 482, 496
gecko, in, 458
genus, 36
giant, of Lingard, 286
goat, 67, 238, 244. V. Goat
goat-sucker, in, 439
gobii, descripdon, 494
Gobio Jluviatilis, in, 483, 495
Gobius giuris, in, 483
niger^ in, 483, 494
goldfinch, in, 440
granulosum, 23, 483
description of, 490
var. parva, 490
grayi, 509
green frog, in, 461
grobbenl, 26
gudgeon, in, 478, 483, 495
guinea-pig, in, 105. V. Guinea-pig
hamster, in, 105
hairy woodpecker, in, 441
Harpoi-ynchus rufus, in, 441
hawk, red-shouldered, in, 441
Helobdella algira, in, 474
himalayamim, 345
Hirundo 7-ustica, in, 442
INDEX
533
Trypanosoma, in horse. V. Horse
house-martin, in, 442
-wren, in, 441
human, 352
Hyla arborea, in, 469
lateristriga, in, 469
viridis, in, 461
Icterus ga lb ula, in, 441
Indian kite, in, 442
raven, in, 440
inopinatuin, 462, 475, 478
description, 473
Java sparrow, in, 441
jay, blue, in, 441
jay, sp. (?), in, 454
johnstoni, 18, 23
description, 445
in estrelda, 440
karyozeukton, ^6j, 468
kingfisher, in, 440
langeroni, description, 495
Laniarius criientus, in, 442
lark, and, 446
laterncs, description, 494
laverani, 442
description, 454
in goldfinch, Spinus tristis, 454
leech, in, 474, 504
leucisci, description, 495
Leuciscus, 483, 495
cephalus, in, 495
lewisi, 8, 14, 15, 17, 19, 20, 24, 25, 58
agglomeration of, 80
cultivation of. 13, 76
differential chaiaciers of, 73
flea, in, 88
guinea-pig, 20, 66, 72, 86, 91
lice, 88
nucleus of, 20
preservation of, 74
radium, action of, 76
rat, in, 15, 21, 28, 30, 61, 68, jj, 88,
94
study of, 68
X rays on, 76
Limanda platessoides, in, 483, 494
limandcs, description, 494
livgardi, 345
lizard, in, 458
loach, in, 480, 481, 496
longocaudense, 20, 60
loricatum, 463
Lota vulgaris, in, 483
lote, in, 478
luis, 47
Lynodontis schal, in, 482, 496
Mabuia raddonii, in, 458
Macrones cavasius, in, 483
seenghala^ in, 481
tengara, in, 481
measurements of, 16
mega, 463, 467
Meles taxus, of, no
Melospiza fasciata, in, 441
Mertila merula, in, 442
TTiigraioria, in, 441
mesnili, 441
description, 453
in Buteo lineatus, 453
Milvns govinda, in, 442
minnow, in, 483, 495
mole, in, r, 58, 109. 110
monkey. V. Monkey
mosquito, in, 43, 508
mouse. V. Mouse
mugil, in, 482, 496
mule. V. Mule
musculi, 10 r
myoxi, 107
Trypanosoma, namini, 203
nelspruitense, 463
description, 475
Neophron pej-cnopterus, in, 442
newt, in, 464, 477
nicolleoruvi, 108
Nictico7-ax gardenia, in, 442
Nile fish, in, 482, 496
noctu(S, 20, 21, 24, 41, 89, 167
noke, in, 482, 496
Opkiocephahis, in, 481
owl, in, 24, 440, 443
paddcB, 441
action of serums on, 451
agglutination of, 449
cultivation of, 449
description of, 448
inoculation experiments, 450, 453
Passer domesticus , in, 441
pecaudi, 226
Perca fluviatilis , in, 480, 483, 495
perccB, description, 495
perch, in, 479, 483, 495
pestanai, no
pheasant, in, 442
fhoxini, description of, 495
Phoxintis Icsvis, in, 483, 495
Phyllostoma, in, 107
pig. V, Pig
pigeons, in, 440
pike, in, 479, 481, 485
plaice, in, 483, 493
platesscs, description, 493
Platessa vulgaris, in, 493
Platophrys laierna, in, 483, 494
Pleiironectes Jlesus, in, 482-3, 493
platessa, in, 482-3, 493
polyplectri, 442
description, 455
Polyplectrum germani , in, 442
Polypterus, in, 482, 496
preservation of, 29
Prussian carp, in, 480
pythonis, 459
description, 459
python, in, 459
rabinowitscki, 105
rabbit. V. Rabbit
Raja clavaia, in, 481, 492
macro7'ynchus , 481, 492
microcellata, 482
tnosaica, 481, 492
punctata. 481, 492
raj(S, description of, 4923
Rana angolensis, in, 463, 475
escuknta, in, 461-2, 465, 469
temporaria, in, 462, 464, 465, 468
■ theileri, in, 463, 475
trinodis, in, 468
rat. V. Rat
ray, in, 481
red-eye, in, 481, 483, 495-6
remaki, 18, 21
description of, 485
magna, 485
parva, 485
multipHcation forms of, 502
reptiles, in, 3, 7, 457
Rhipicephalus sanguineus , in, 508
RhoTubus l(2vis, in, 483, 495
river bull-head, in, 483
roach, in, 483, 495
robin, in, 441
rockling, in, 479
roller-bird, in, 440, 443
rotatorium, 15, 17, 20, 23, 27, 457, 462-:
466, 469
cultivation of, 470
description of, 465
534 TRYPANOSOMES AND THE TRYPANOSOMIASES
Trypanosoma rotatorium, morphology of, 471
synonyms of, 465
var. nana, 462
rougetif 314
rudd, in. V. T. in red-eye
saccobranchi, 483
description of, 496
Saccobranckus fossilis, in, 483,496
sanguinis, 34, 90, 461
description of, 460
Scardinius erythropkthalmus ^ in, 481, 483,
495. 496
Scolephagus carolinus, in, 441
scardinii, description of, 495
scyllii, description of, 492
Scyiliwn ca?iicuH, in, 481, 492
stellare, in, 481, 492
sexual forms of. V. Sexua] forms of T.
Sialia sialis, in, 441
Siluridas, in, 496
Silurjts clarias, in, 482, 493
sole, in, 481, 491
solecB, 18, 21
description of, 491
Solea vulgaris, in, 481, 491
somalense, description of, 464, 477
song-sparrow, m, 441
song-thrush, in, 442
spermophile, in, 106
Spinus tristis, in, 441
squalii, description, 495
Squalius cephaltis, in, 483, 495
squirrel, in, 106
sterlet, in, 479
sub-genus, 34
suis, 114
swallow, in, 440, 442
Syrnium aluco, in, 439, 444
Tachypkormus ornata, in, 442
tadpole, in, 462
Talpa europcea, in, no
talpcE^ n. sp., no
tench, in, 478, 481
theileri, 20, 205, 343
description of, 347
Tinea tinea, in, 480-1, 489
vulgaris, in, 483
tinea, description of, 489
toad, in, 464, 477
transvaaliense, 21, 347, 348-9
Treron calva, in, 442
Trichogasterfaseiatus, in, 481
Troglodytes cBdon, in, 441
tseise-flies, and, 2, 4, 26, 38, 156, 167,
403- 508
iulloehi, description, of, 510
Turdus niusicus, in, 442
ugandense, 355, 402
undulans, 463
vespertilionis , 107, 108
vivax, 28, 73, 117, 199
infection with, 200
vulture, Egypt, in, 442
yellow-hammer, in, 442
Zenaidura macroura, in, 441
ziemanni, 43
Trypanosomatid(S, 37
Trypanoscme fever (so-called), 370
Trypanosomas, agglutination of, 30
biology of, 27
comparative study of, 16
cultivation of. V. Cultures
fishes, grouping of, 505
mode of multiplication of, 502
infectivity of, 28
mammals, of small, 98
movement of, 27
nutrition of, 27
Trypanosomes, pathogenic, methods of iden-
tifying, 187
preservation of, 13, 29
virulence of, 28
Trypanosomiases of Abyssinia, 202
of Abyssinian frontier, 207
of Algeria, 210
of Anglo-Egyptian Sudan, 203
of Annam, 286
of Cameroon, 199
of Entebbe, 208
of Erythrea, 202
of French Guinea, 226
Sudan, 219 ,
of Gambia, 219
of German East Africa, 190
of horses in Annam, 286
Gambia, 229
of Somaliland, 201
of Togoland, 193
of Uganda, 204
treatment of, 415, V. Treatment
Trypanosomiasis, human, 352
Trypanosomidcs, 36
Trypanosomosis, r
Trypanozoon , 26, 33
criceti, 105
Trypanred, 6, 95, 173
in caderas, 308
in dourine, 339
in surra, 282
in treatment, 420, 422-5
mode of action, 425
and T. gambiense , 412
Trypanrot, 173, 308. V. Trypanred
Tumby-a, 292
Tumby-baba, 292
Turdus musicus, T. in, 442
Turtur humilis, 289
Tsetse-flies, the, 511
and their trypanosomes, 2, 4, 26, 38,
156, 167, 403, 508
and dog, 165
and horse, 165
mode of reproduction, 514
rdle of, 2
Uganda, T-ses of, 204
Undulating membrane, 16, 22
Undulina rana?-um, 32, 461
Vacuole, 19
Value of therapeutic measures in the T-ses,
42s
Vespertilio kuhli, 108, no, 217
nattereri, T, of, 108
noctula, 108
Vesperugo pipistrellus , T. of, 108
serotinus, T. of, 108
Virulence of trypanosomes, 28
Vulture, Egypt, T. in, 442
Wildebeest, nagana in, 140, 16S
Woodpecker, hairy, T. in, 441
Wren, house, T. in, 441
X rays, action of, 419
in treatment, 434
on T, lewisi, 76
Yellow-hammer, T. in, 442
Zebra and T-sis, 192
and Togo virus, 197
Zebus, soumaya of. K Souma
Zenaidura macroura, T. in, 441
Zeus faber, 482
Zusfana, mal de la, 186, 211, 33
INDEX
535
AUTHORITIES
Adami, 115, 186, 202
Agatarchides, 115
Ahlbory, 365
Alvares, C, D. , 60
Annett, 29, 231, 241
Aragoa, 442, 455
Arkhangelsky, 338
Athias, 463
Aubert, 190, 426
Austen, 112, 166, 208, 244, 511, 515, 517, 518,
520
Bagshawe, 413, 515
Baker, 355
Balbiani, 32, 247
Baldwin, 142, 145
Baldry, 313, 316, 320, 339
Balfour, A., 38, 115, 186, 203, 364
and Neave, 416, 434, 516
G. W., 169
Barron, 354
Battaglia, 108
Bayliss, 319
Bell, 262, 464, 490
Bellay, Griffon du, 352, 391
Beneden, Van, 503
Berg, I, 479, 484
and Creplin, 479
Bergeret and Bonin, 331
Beltencourt, 353. 354, 366, 378, 393
and Franca, 104, 108, 109, no
Billet, 44, 464, 474
and Marchal, 312, 328
Bin, 51
Blaise, 328
Blanchard, R., 126, 174, 248, 345
Blandfurd, 7, 29, 66, 90, iii, 122, 125-9, ^S^'
134, 149, 152, 154
Blin, 248, 249, 288
Blochmann, 36
Bodin, 249
Bonin, 331
Bosc, 104
Bouin, P., 54
Bouffard, G., 225, 429
Bouet, 464, 466, 471
Bradford, 8, 51, 367
and Plimmer, 125, 131, 138-9, 145
Braid, James, 169
Brau, 249, 287
Brauer, 307
Brault, 354
Breinl, A., 46, 240, 393, 404
and Todd, 436, 437
Broden, 23, 113, 116. 353, 356, 366, 368, 378,
411, 420,434,463
Broden and Rodhain, 436, 438
Brornan, 54
Bruce, David, 2, 5, 6, 29, in, 114, 127, 136,
138-9. 151. 164-5, 170, 186, 204, 354-8,
364- 370. 376. 433. 513
James, 115, 516
and Nabarro, 61, 398
and Greig, 392, 407
Brumpt, I, 29, 61, 105, 107, 112. 115. 120,
186, 201-2, 355, 366, 382, 384-5, 406,
464, 474-8, 483, 495, 499, 501, 504, 506,
S18
and Lebailly, 483, 494
Brumpt and Wurtz, 387, 389, 411
Buard, 60
Buffard. V. Schneider and Buifard
Busck and Tappeiner, 419
Busy, 328
Butschli, 32, 33, 36
Byloff, 62
Cagigal, 353
Calmette, 60
Campbell, W. G. , 248]
Campenhout, Van. 362, 378, 435, 436
Carougeau, 249, 266, 272
Carr^, 278
Carter, 408, 516
Carter, Vandyke, 59, 247
Castellani, 6, 353-4-5-6. 373. ^02, 404. 4n, 433
and Willey, 482, 496
Cazalbou, 118, 120, 186, 205,219,224,225,229
282
Cerqueira, 442, 455
Certes, 34
Clarke, 352, 391
Clegg, 25T
Cochrane, 360
Cook, J. H. , 363
Corre, 352, 376
Coutts. J. M., 253, 261, 264, 266, 268
Chalachnikov, 2, 32, 35, 59, 60, 77, 105-6, 439,
462, 465-6, 480. 484, 500, 502
Chantemesse, 128
Chapman, James, 114, 313
Chaptol, 249
Charnioy, de, 280
Chassaniol, 352, 366
Chatterjee, 37, 49
Chaussat, i, 58, 90, 460, 479
Chauvrat, 121, 210, 314
Chenot, 329
Chichester, 117, 420
Christophers, 37, 48, 49
Christy, 186, 353, 356, 364, 366, 369, 370. 381,
397, 400, 412
Creplin, 479
Crookshank, 2, 33, 59, 247
Cumming, Gordon, 114
Currie, 361
Curry, 251
Dangaix, 352, 391
Dangeard, 54
Daniels, 354, 438
Danilewsky, 2, 32, 33, 36, 40, 59, 60, 70, 439,
443. 461, 465. 480, 502
Daniec, Le, 352
Daruty, 279
D'Anfreville, 435
Decorse, 120, 230, 519
Deixonne, M., 251-2, 258, 279, 283-4
Demoor, A., 142-3
Diesing, 117, 178, 180, 185-6, 199, 201
Dionisi, 107
Does, De, 313, 341
Doflein, 33, 36, 40, 313, 489
Donovan, 48, 51, 74, 106, 248, 440
Dryepondt, 362, 378
Drysdale, J. J., 165
Dupont, 367, 378
Dupuy, 119
Durham, 7, 29, 66, 90, 107, in, 122, 125-6,
128-9, 130, 134, 141, 149, 152-3-4
Miss Florence, 112
Durme, Van, 142, 143, 419
Durrant and Holmes, 345
l^utroulau, 392
Dutton, 5, 6, 26, 29, 344, 354, 356
and Todd, 60, 99, 113, 119, 354, 359, 366,
370. 376, 379. 381-2, 387, 397-8. 4~[4, 439,
440, 462, 445, 467
and Christy, 401, 434
and Newstead, 516
Eberth, 32, 440
Edington, A., 61, 252, 261, 264, 266, 268, 283
536 TRYPANOSOMES AND THE TRYPANOSOMIASES
Eisath, G., 395
Ehrlich and Shiga, 6, 173, 296, 306, 308-9,
415. 425
Elmassian, 5, 292, 294, 299, 300, 302, 307, 308
Evans, G. H., 246, 261
Fay, 362
Fellmer, 416, 434
Figueiredo, A. de, 353
Fo^, 114, 121, 1S5, 514
Forde, 6, 354, 378
Franpa and Athias, 463, 469, 470
Carlos, 368, 517, 519
Francis, 8, 59, 65, 74, 80, 81, 87, 88, 90, 94
Franke, 415
Gaigneron, 392
Galli- Valeric, 107
Gaule, J., 461
Gehrke, 458
Ghika, N. D., 115
Gibson, 248, 258
Giemsa, 10
Giles, G. M., 516
Girard, 368
Gluge, 31, I, 460. 462
Goebel, O. , 27, 122, 140, 143, 148, 159, 419
Gouzien, 248
Gowers, W. F. , 117
Grassi, 33, 60, 461
Grattan, 360
Gray, 38, 186, 202, 204, 210, 364, 368, 376, 379
and TuUoch, 206, 358, 386, 403. 405, 411,
420, 434, 508
Greffuhie, 186
Greig, 29, 114, 144, 169, 186, 190, 202, 204,
2IO, 354-5, 364, 368, 370, 376, 379, 385,
420, 433
and Gray, 206, 386, 397, 400, 401, 411,
434
Griffiths, 203
Gros, I, 58, 439, 479
Grothuien, 133, 192
Gruby, i, 25, 31, 460, 462, 465
Gii^rin, 352, 359, 372, 392
Guignard, 53
Gunn, 247
Giinther, 378
and Weber, 368
Haig, 248
Halban, 174
Halberstaedter, 13, 142, 144, 146, 296, 302,
306, 415
Hallen, 115, 202
Hanna, 439
Hare, 78
Harris, W. C., 114
Harvey, 356, 410
Hend, A. S., 115, 186, 203
Heidenhain, 11
Haider, 54
Henneguy, 53
Hertwig, 56, 337
Hesse, 503
Hewby, 117, 186
Hirsch, 352
Hodges, 363, 364, 414
Hofer, 500
Hoffmann, 47
Holmes, 102, 274, 345, 346
Hubenet, 341
Hultgen, 66
Hutcheon, 343
Ishikawa, 54
Jakimoff, W. L., 122, 126, 130-1, 141-S, 149,
157, 296, 299, 301, 305, 334
Jenner, 10
Jolyet, F., 103
Jurgens, 59, 74, 77, 80, 90
Kanthack, 7, 29, 66, 90, iii, 122, ,125, 126-9,
130, 134, 141, 149, 152-4
Kempner, 3, 8, 51, 59, 60
Kendall, A. I., 61, lor
Kent, Saville, 32, 40, 58
Kermorgant, 249, 359
Kerr, 48
Keysseliiz, 24, 26, 483, 490, 498, 501, 503,
506
Kinghorn, 46
and Todd, 363
Kinyoun, 251
Kisskalt, 108
Kitasato, 60
Kleine, 178, 179
and Moellers, 189, 199, 418
Knapp, 46
Koch, 29, 38, 74, 112, 118, 156, 167, 183, 186,
190. 344, 365. 435- 50S
Kohl, Nina, 334
Kolle, 343
Koninski, Karl, 464
Kopke, Ayres, 354, 362, 393, 435, 436
KorfF, von, 53
Korfchelt, 54
Krueger, 361
Kruse, 355, 465, 480
Krzysztalowicz, 46, 337
Kuborn, 353
Kudike, 366
Kiimmer, 192
Kunstler, 35, 105, 457
Labb^, 33, 35
Laboulbene, 116 ,
Lacerda, 292
Lacomme, L., 129, 169, 418
Lafosse, 338
Landsteiner, I74
Lankester, Ray, 31, 461
Lanzenberg, 437
Lascaux, 119
Laveran. A., 2, 5, 32, 59, 109, 118-9, 174, 186,
203, 219, 225-6, 229, 245, 247, 262, 266,
283, 343, 351, 357-8, 360, 387, 389, 411,
425. 433, 437, 439, 448, 463-4, 475, 483,
498, 516, 520
and Martin, 230
and Mesnil, 25, 51, 59, 61, 69, 7$, 87, 112,
116, 118, 122, 123, 141, 154, 174, 188-9,
231, 233, 241, 264-8, 272, 277, 286, 289,
290-1, 314, 348, 420, 457, 462, 481, 485,
488-9, 490, 492, 496, 502
Lebailly, 483-4, 490. 493. 495
Lecler. V. Sivori and Ijccler
Ledoux-Lebard , 87
Lees, Kay, 278
Leger, 22, 24, 26, 32, 37, 40, 41, 55, 483, 489,
496, 498, 501, 503
Leidy, 32
Leicester, 248, 250
Leishman, 48
Lemaire, 116
Lepierre, 353
Lepinte, 249
I-esur, Aime, 252
Alfred, 251-2, 256-7
Leuckart, 32, 440
Levaditi, 38, 441, 448
and Sevin, 451
Lewis, I, 2, 32, 90
T.,58
J., and Williams, H. V., 463, 470, 475
Leydig, 457, 503
Lherminier, 392
Lieberkuhn, 461
INDEX
537
Ligniferes, 136, 139, 169, 188, 292, 295, 299,
300, 304, 306-7, 330, 336-7
Lingard, 5, 17, 58, 67, 90, 102, 170, 247-B, 254,
256-7, 261, 266, 278, 280, 281, 282, 285, 313,
316, 318-9, 320, 337, 345-6. 480
Linton, 356
Livingstone, 114, 121, 164, 169, 513
Lorand, 376, 434.
Low, 353, 373, 377, 379, 393, 411, 433
and Castellani, 433
Liihe, 26, 33, 40, 105, 344, 345, 348, 403
Luhs, F., 344, 346
Lustrac, 34
Mah6, 352
Maillard, 54
Manca, 104, 483, 490
Manders, N., 253, 280
Manson, P., 29, 353-4, 358, 366, 378, 392
and Daniels, 412
Marchal, 312, 338
Marchoux, 353
and Salirabeni, 464, 469
Marek, 320
MarkI, 141, 142, 168
Martin, C. J., 264
G. , 119, 186, 205, 227, 241, 361, 458
1'-. 372, 378, 380, 437
and Girard, 368, 406
Martini, F., 59. 73, 113. 122, 133, 135, 141, 155,
178-9, 183, 186, 192, 193, 196-8
Martoglio, 115, 186, 202
Massaglia, A., 142, 145, 146, 271, 418
Massey,Yale, 408, 517
Mathis, 14, J7, 130
Maus, 251
Maxwell-Adams. 355
Mayer, i, 31, 135, 142-3, 150, 365, 460,462
McNeal, 3, 25, 38, 44, 67, 70, 88, 92, 149, 155,
161
and Novy, 59, 61, 77, 78, 87
Megnin, 165
■Meinmo, 115, 186, 202, 205
Mendes, 354, 436
Mense, 419, 434
M^ricourt, Le Roy de, 352
Mesnil, 6, 32, 40, 45, 48, 52, 89, 104, 108, 116,
144, 184, 194, 201, 208, 212, 322, 321^, 330,
368
Mesnil and Martin, 122, 140, 148, 177, 181, 301
and NicoUe, 190, 415-6, 426, 428
and Aubert, 426, 432-3, 438
and Rouget, 213, 217, 330, 336-7, 340
Meves, 53, 54
Migone,' 292, 300,302, 307, 308
Milne-Rd wards. 461
Minchin, 37, 38, 167, 413, 511, 516
Gray and TuUoch, 458, 510
Mitchell, W., it2
Mitrophanov, 2, 27, 33, 480, 484
Mobius, 34
Moffat, 363, 367, 369
Mole, 393
Mollereau, 248
Mollers, 178, 179
Monfallet, 313
Montel, 249, 482, 493
Moore, 102, 117, 170, 186
and Chichester, 420
B., 422
J. E. S., 152
J. E. S. and Breinl, 404
Moreau, E., 492
Morel, 120, 513
Morax, V , 322
Mott, F. W., 48, 206, 209, 272, 313, 316, 319,
320-1, 322, 353, 368, 370, 379, 393-6, 405
Moutier, 368
Musgrave, 186
Musgrave and Clegg, 60, 65, 74, 251, 259, 266,
277, 280, 285
and Williamson, 251, 266
Muratet, 481
Mutin-Boudet, 249, 287
Nabarro, 6, 29, 114, 122, 141, 144, 169, 190,
202, 204, 210, 344, 346, 354-6, 358, 364,
368, 370. 376-7t 420, 433, 463
and Greig, 230, 385-6, 408, 436, 516
and Stevenson, 476
Nabias, B. de, 103
Nattan-Larrier, 378
Neave, 48, 442, 455, 482, 496
Neporojny, 143-5
Nepveu, 354
Newstead, 516
Nicolas, 352
Nicolle, 6, 48, 104, 184, 217
and Comre, 108, 110
and Remlinger, 332
Nielly, 352, 392
Nierenstein, 422
Nissle, 142, 145, 418
Nobde, de, 159, 419
Nocard, 112, 127, 129, 137-8, 165, 180, 188,506,
313. 3^7, 324. 328, 330, 332, 336, 337-8.
340
and Leclainche, 312, 338, 341
and Valine, 259, 278
Nocht, 8, 135
and Mayer, 365, 403
Novikoff, 338
Novy, 3, 38, 44, 46, 156, 167, 508
and McNeal, 112, 159, 160, 441, 451,
453-4. 475
and Hare, 247, 273, 276, 278
and Torrey, 508
Nuttall, C. E., 247
Ochmann, 114, 186, 193
Osier, 247
Panisset, 221, 247, 269
Panse, 191, 344
Patton, 50
Pease, 246, 255, 258, 261, 264, 282, 312-3, 315,
322. 325, 330, 336, 339, 340
P^caud, 118, 186, 219, 224, 225, 229
Penning, 60, 250, 254, 266, 280
Perrin, 34
Petrie, 13, 59, 71, 74, 104, 108, 441, 442, 482,
488
Peuch, 338
Pfeiffer, 38
Phillips, 48
Pierre, 119
Pilchford, 185
Plehn, Miss, 22, 35, 483, 488, 499, 500
Plimmer, 8, 12, 29, 51, 357
and Bradford, 111-2, 121, 141, 151, 154, 242
Poche, 26
Prenant, 54
Pricolo, A., 101-2, 274
Prince, 337
Prowazek, 20, 21, 24, 32, 38, 41, 59, 68, 79,
88-9, 143-4, 152, 155, 167, 403, 449, 511
Rabinowitsch, 3, 8, 51, 59, 60, 331
and Kempner, 61, 64, 68, 70, 85, 88, 90,
105. 151. 306, 329, 331-2, 339
Raillet, 60, 165, 214
Rattig. 1, 461
Ray Lankester, i, 31, 461
Remak, i, 461, 479
Remlinger, 48, 332
Renner, 360
Rennes, 120, 186, 211, 212, 314
Rezende, de, 354
538 TRYPANOSOMES AND THE TRYPANOSOMIASES
Richard, 119
Robertson, 459, 482
Rodet, A., and Vallet, G., 143, 145, 418
Rodhain, 435
Roger, 186
and Greffulhe, 213
Rogers, 48, 49, 74, 257, 279
Romanowsky, 8
Ross, 12, 44, 152, 159, 167, 419
Rost, E. R., 283
Rouget, s, 61, 210, 313-4, 322-4, 326, 328, 331,
338-9
Roux, G., 418
Ruge, 12
Russ, 76, 419
Sa, Dias de, 368
Sabrazis and Muratet, 60, 481, 484, 490
Saint-Sernin, ,249, 287
Salimbeni, 464
Salmon, 313
and Stiles, 251
Sambon, 40, 406
Sander, 191, 516
Santelli, 352
Sauerbeck, 141-2, 144, 302
Saville Kent, 32
Savour^, 115, 186, 202
Sawtchenko, 93
Schat, 250, 254, 259, 279
Schaudinn, 20, 21, 23, 24, 39, 41, 42, 45, 47,
52, 56, 89, 167, 440, 445
Schild, W. , 437
Schilling, 29, ir2, 118, 122, 135, 140, 148, 155,
178, 180, 186, 193, 194-6, 344
Schneider, 332, 333
and Buffard, 5, 210, 312, 313-4, 316, 318,
320, 324, 328, 332-3, 335, 337, 338, 340-1
Schmidt, 166, 191
Schoch, 165
Schoo, 60
S^guin, 249
Senn, 3, 8, 21, 32, 33, 36, 40, 52, 55, S9. 4^6
Sergent, Ed. and Et,, 37,74, 108, 120,211,214,
218, 314, 336, 419, 440, 462, 464
Sevin, 451
Shiga, 6, 173, 296, 306, 308-9, 415, 425
Sicard and Moutier, 368, 393, 406
Siebold, Von, 461
Siedlecki, 46, 337
Simond, 458
Sivori and Lecler, 61, 74, 88, 292, 294, 306-7
Sjbbring, 442
Slee, 251
Smedley, 59, 80, 161
Smith, Alien, 251
Donaldson, 115
Major, 118, 186, 230, 516
Speiser, 351
SpreuU, 343
Stahelin, 194
Statham, 48, 50
Steel, J. H., 247, 256, 269, 280
Stein, 32, 440, 461
Stephens, 37, 381
and Newstead, 516
Stevenson, 122, 141, 463
Stordy, R. J., 61, 114, 186, 207, 374
Strasburger, 53
Stuhlmann, 166, 190, 192
Szewczyk, 120, 186, 211, 314
IIS, 134. 185-7, 201,
Tanon, 378
Tappeiner, 419
Tartakovsky, 60
Tautain, 119, 226, 408
Taylor and Currie, 361
Teppaz, 242, 245
Terry, B. T., 61, 65
Theiler, 5, 61, 112-3,
343-4, 346, 514
Thiroux, 44, 61, 74, 99, 356, 412, 441, 448-9,
466
and D'Anfreville, 435-6
and Teppaz, 242, 245
Thomas, 6, 61, 184, 415, 421, 434
and Breinl, 228, 231, 233, 241, 255, 264-8,
272, 276, 296, 299, 302, 305, 325, 327,
330-1. 357-8. 377. 382, 386, 389, 391,
397. 405. 418, 42s. 434
and Linton, 356-7, 382, 384-5, 387, 390
Thomson, J. D., no
Tobey, 366, 464, 477
Todd, 5, 26, 29, 344, 356, 362, 401, 422, 435
and Tobey, 366, 377
Torrey, 38
Trasbot, 338
Tr(51ut, 338
TuUoch, 38, 358, 368
Valentin, i, 31, 479
Valine, 247, 278, 331, 390
and Carr^, 188, 278
and Panisset, 188, 222, 260, 278
Vallon, 214
Van Beneden, 503
Van Campenhout, 362, 378, 435, 436
Vassal, 61, 249, 251, 253, 286, 289, 442, 455
Vies, 34
Voges, 140, 292, 306, 310, 311
Von Siebold, 461
Vrijburg, 250, 257
Warrington, 393
Wasielewski, 3, 8, 21, 32, 52, 55, 59
and Senn, 70
Wassermann, 365
Weber, 368
Wedl, I, 439, 461, 479
Wellman, 359, 442, 455, 517, 520
and Fay, 362
Wendelstadt, 416
and Fellmer, 434
Wenyon, 190, 431
Westwood, 115
Wiggins, 365, 408
Willey, 482
Willems, 368
Williams, H. V., 464
Williamson, 251
Wilson, E. B. , 54
Winterbottom, 352
Woodcock, 19, 26, 52, 108, 333, 474
Wright, 48, 51
Wurtz, 29, 382, 384, 385
Wyndham, 364
Yersin, 249
Zabala, 292
Ziemann, 3, 8, 24, 28, 61, 66, 73, H2, 116, 118,
129, 186, 193, 19S-6, 200, 353, 361, 440,
462
Erratum. — Page 384, line 8 from top. fur- [102-2° F.] read [ioi'3° F.].
Bailliere, Tindall &^ Cox., 8, Henrietta Street^ Covent Garden
DESCRIPTION OF PLATE.
I.
T. letvisi.
8.
r. theileri.
2.
Multiplication form of T. lewisi.
9-
T. transvaaliense.
3-
T. lewisi.^ small form resulting
10.
T. avium.
from the disintegration of a
II.
T. da7nonice.
rosette.
12.
T. solece.
4-
T. brucei.
13-
T. granulosum.
5-
T. equinum.
14.
T. rajcE.
6.
T. gambiense.
15-
T. rotatormm.
7-
The Same, undergoing Division.
16.
Tpl. borreli.
All these figures have been drawn from preparations stained by the eosin-
Borrel-blue-tannin method described in the text, under a magnification of about
2,000 diameters, with the exception of Fig. 15, which was drawn under a magnifi- ^
cation of about 1,400 diameters.
A.La-verau. del.
V.Roiassel,lit}i.