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HOOKWOKM DISEASE 
 
 ETIOLOfxY. PATHOLOGY. DIAGNOSIS. PEOCtXOSIS, 
 
 PEOPHYLAXIS. AM) TPtEAT3IEXT 
 
 GfEORGE DOCK, A.M.. M. D.. 
 
 PROFES.SOK OF THE THEORY A>rX> PKACTICE OF MEDICIXE, MEDICAL 
 DEPARTMENT TULAXE r^N'IVEKSITY OF LOUISIANA, NEW ORLE4.SS, 
 
 AX J; 
 
 CHAELES r. BASS, M. D., 
 
 IX.STRIXTOK OF CLINICAL MICROSCOPY AND CLINICAL MEDICINE, MEDICAL 
 DEPARTMENT TCLANE rNTVERSITY OF LOUISIANA, NEW ORLEANS. 
 
 ILLUSTRATED WITH FORTY-NINE SPECIAL 
 EXGRAVLVGS AND COLORED PLATE 
 
 ST. LOUIS 
 C. V. MOSBY COMPANY 
 
 1910 
 

 Copyright, 1910, by C. V. Mosby Company' 
 
TO 
 
 CHARLES WARDELL STILES, Ph. D., D. Sc, 
 
 Chief of the Divisiot^ of Zoology in the Hygienic Laboratory, United 
 
 States Public Health and Marine Service, 
 Whose brilliant conceptions and untiring labors hwe enlarged our 
 
 knowledge of HOOKWORil DISEASE, AND THEREBY OPENED UP ONE OF 
 THE MOST IMPORTANT FIELDS OF PREVENTIVE MEDICINE, 
 
 THIS VOLUME IS DEDICATED BY 
 
 THE AUTHORS. 
 
PREFACE. 
 
 Few diseases surpass the subject .of this work in the 
 strangeness of its history, the importance of its ravages, or 
 the theoretic ease of its extinction. 
 
 It probably existed from remote antiquity among trop- 
 ical peoples, and, although attempts have been made to 
 trace it back to a very early period, these efforts fail for 
 lack of the careful clinical methods of diagnosis that are 
 necessary for the recognition of such diseases. For almost 
 fifty years after the disease was made known in Italy, and 
 after it had been the subject of many important investiga- 
 tions in diagnosis, biology, and treatment, it remained for 
 us in America chiefly an interesting, but remote, fact, de- 
 void of practical relations. Its absence was accepted as 
 evidence of the greater personal cleanliness and superior 
 mode of life of our citizens, and at most it was feared that 
 among recent immigrants cases might be imported and even 
 spread in less favorable localities. No more striking ex- 
 ample of the transitory state of medical knowledge can be 
 advanced than the proof brought within the last few years, 
 not only that hookworms exist as human parasites in a 
 large part of the country, but that they may with reason be 
 looked upon as among the most important causes of diseases 
 of the South in extent, in destruction of life, and in leading 
 to physical and mental degeneration. The fact that the 
 parasites in the United States belong to a new species is a 
 most important one and very suggestive in its bearing on 
 medical zoology. 
 
 9 
 
10 PEEFACE. 
 
 In many parts of Europe hookworm disease is one of the 
 most important economic problems. Immense labor and 
 expense have been devoted to the measures for its repres- 
 sion in Belgium and Germany especially, where it seriously 
 affects the mining industry. 
 
 The study of hookworm disease in America has shown 
 the heav}" load that endemic disease lays upon a country. 
 Largely due to it, a region that should be most fertile lies 
 relatively uncultivated; a population derived from the best 
 colonizing blood ekes out a miserable existence, and is 
 doomed to extinction unless it is soon relieved of its infec- 
 tion. Thanks to the painstaking labors of zoologists and 
 physicians, much has been learned of the disease and its 
 parasite. Physicians and hygienists have realized that the 
 evil, preventable as it is, must stop, and medical men, ad- 
 ministrative officers, and private philanthropists are now 
 working actively to that end. 
 
 In the widespread effort at extermination many forces 
 must co-operate. Physicians will be called upon to treat 
 the disease in its various forms, as well as to assist in its 
 prevention. For them j^rimarily this book has been writ- 
 ten, for the authors have for a long time been interested in 
 the medical features of the disease. Hygienists, employers 
 of labor, and others interested in sanitation may also find 
 information of practical value. How well we have suc- 
 ceeded we leave to our readers. We take pleasure in 
 thanking many well-known authorities for the use of 
 material and illustrations, especially Dr. C. W. Stiles, Allen 
 J. Smith, Claude A. Smith, and H. F. Harris. Many others 
 whose works we have drawn upon freely, and who have 
 accomplished important work on the subject, are mentioned 
 in the following pages. 
 
 "We have avoided bibliographic references, except in rare 
 instances, believing that those who wish to consult original 
 
PEEFACE. 11 
 
 sources will have to use the "Index Medicus" in any event. 
 We have also repeated certain statements in order to make 
 easier the use of the book for reference by those who wish 
 to gather practical lessons from it. 
 
CONTENTS. 
 
 CHAPTER I. 
 
 PAflK 
 
 Definition — Synonyms — Historical — IVCythical period — Early references 
 in seventeenth, eighteenth, and early nineteenth centuries — Du- 
 bini and the recognition of ankylostoma in the human body — 
 Bilharz, Griesinger, and others, and the recognition of pathologic 
 relations — St. Gothard tunnel anemia and the lesson it gave — 
 Work of Perroncito, Parona, and others in Italy, Switzerland, and 
 Germany — Leichten stern and the anemia of brick workers and 
 miners— Early references to hookworm disease in America under 
 the names of dirt eating, malarial cachexia, etc. — Later history, 
 with the discoveries of A. J. Smith, Harris, Stiles, Claude A. 
 Smith, and others — Discovery of the skin infection by Looss and 
 its confirmation by others 17 
 
 CHAPTER II. 
 
 United States — Geographic distribution — Intensity — Economic impor- 
 tance — Climate — Soil — Occupation — ^Barefooted Children ... 33 
 
 CHAPTER III. 
 
 Zoologic features — Clasaification of hookworms — Nearly related, simi- 
 lar, and allied worms — ^Historic data regarding nomenclature, 
 genera, and species — Ankylostoma duodenale — Anatomy — Necator 
 Americanus — Development — Reproduction — Existence outside the 
 human body — Effects of chemical disinfectants 46 
 
 CHAPTER IV. 
 
 Modes of infection — Conditions that favor development of larvae — In- 
 fection by drinking water and by food — Skin — Ground itch and 
 its relation to infection by hookworms — Disposition of feces and 
 its part in hookworm infection ... . 70 
 
 CHAPTER V. 
 
 Pathologic anatomy and pathology — Post-mortem appearances — Blood 
 — Skin — Intestines — Pathology — Anemia and its causation, as by 
 sucking blood, by hemorrhage following bites, by hemolytic and 
 other poisons — Loss of mucus — Lesions of the intestine — Infec- 
 tion of the bites — Blood changes 94 
 
 13 
 
li CONTEXTS. 
 
 CHAPTER VI. 
 
 PAGE 
 
 Symptomatology — Varieties of types and different degrees of in- 
 tensity — Symptoms and signs on the part of various organs and 
 functions in detail — Blood — Joints — Skin — Ground itch: clinical 
 features; importance in early diagnosis — Liver — Spleen — Respira- 
 tory organs — Circulation — Digestive organs — Dirt eating — Genito- 
 urinary organs — Eyes — Nervous and mental symptoms . . . 115 
 
 CHAPTER VII. 
 
 Diagnosis — Direct diagnosis by examination of feces for ova — Prac- 
 tical examination of stools — Making the preparation for micro- 
 scopic examination — Description of eggs — Number of worms esti- 
 mated from eggs — Differential diagnosis of eggs — Cultivation of 
 larvas from ova — Special methods for greater certainty in find- 
 ing eggs: Pepper's, Bass' — Diagnosis by examining stools after 
 treatment — Blotting paper test — Eosinophile count in diagnosis 155 
 
 CHAPTER VIII. 
 
 Prognosis — Prognosis of infection in various types of disease at 
 various ages — Mortality — Intercurrent diseases and complications 
 — Other parasites 182 
 
 CHAPTER IX. 
 
 Prophylaxis — Its necessity as an economic and sanitary measure — 
 Elements of prevention — Extermination of mature woi'ms — Soil 
 infection and its prevention in theory and practice — Construc- 
 tion and care of privies — Disinfection and its uncertainties — Dis- 
 position of feces — Preventive measures in various exposed trades 
 —Education 189 
 
 CHAPTER X. 
 
 Treatment — ^Treatment of ground itch — Treatment before ova appear 
 in stool — Possibility of early cure — Treatment of hookworms in 
 intestine — Preliminary treatment and its object — Thymol — 
 Dose of thymol — Mode of administration — After-purgative and 
 its object — Dangers of thymol and means of avoiding them — 
 Results to be expected from thymol treatment — Need for repe- 
 tition of treatment — Advantages and disadvantages of other 
 methods of treatment — Beta-naphtol — Male fern — Other drugs — 
 Treatment of symptoms and sequelae — Anemia — Improvement 
 after treatment 207 
 
ILLUSTEATIOXS. 
 
 Intestinal lesions in uncinariasis . . Frontispiece 
 
 PAGE 
 
 Fig. 1. Female uncinaria duodenalis and uncinaria Americana . 51 
 
 Fig. 2. Male hookworm 53 
 
 Fig. 3. Dorsal view of anterior end of the old world hookworm . 54 
 Fig. 4. Caudal bursa and tail of male uncinaria duodenalis and 
 
 uncinaria Americana 58 
 
 Fig. 5. Ankylostoma duodenale in copulation 58 
 
 Fig. 6. Copulating hookworms from dogs 58 
 
 Fig. 7. Male and female necator Americanus 59 
 
 Fig. 8. Dorsal aspect of head end of uncinaria Americana . . 60 
 
 Fig. 9. Lateral aspect of head end of uncinaria Americana . . 61 
 Fig. 10. Dorsal view of head end of uncinaria duodenalis and 
 
 uncinaria Americana 62 
 
 Fig. 11. Embryology of the old world hookworm 62 
 
 Fig. 12. Two larvse of the old world hookworm 64 
 
 Fig. 13. Ova of uncinaria duodenalis and uncinaria Americana . 65 
 
 Fig. 14. Experimental hookworm infection — Soil containing larvae 77 
 Fig. 15. Experimental hookworm infection — Swelling of wrist and 
 
 tendons of hand and vesicle infection 77 
 
 Fig. 16. Experimental hookworm infection — Large crust forming 78 
 Fig. 17. Experimental hookworm infection — Confluent vesicle forma- 
 tion 79 
 
 Fig. 18. Experimental hookworm infection — Uncinarise removed from 
 
 intestines 80 
 
 Fig. 19. Section of skin as seen under the microscope — Hookworm 
 
 crawling through skin 81 
 
 Fig. 20. Hookworm larvse in axillary gland 82 
 
 Fig. 21. Hookworm larvae in blood in heart 83 
 
 Fig. 22. Hookworm larvae in lungs 84 
 
 Fig. 23. Hookworm larvae in trachea 84 
 
 Fig. 24. Hookworm larvae in larynx 85 
 
 Fig. 25. Privy from which soil pollution is being spread ... 87 
 
 Fig. 26. Privy in center of town 88 
 
 E^g. 27. Kind of privy in general use in small towns .... 89 
 Fig. 28. Blood cyst below mucosa of jejunum, with cross section of 
 
 included hookworm 99 
 
 Fig. 29. Hookworm in submucosa, with cross section of body of 
 
 female 107 
 
 15 
 
16 ILLUSTEATIONS. 
 
 PAGE 
 
 Fig. 30. Photomicrograpli of uncinaria Americana sucking mucosa 109 
 
 Fig. 31. Jejunum in a fatal case of uncinariasis 110 
 
 Fig. 32. Mother and three children with hookworm disease . . 116 
 
 Fig. 33. Family of seven with hookworm disease 117 
 
 Fig. 34. Family of six with hookworm disease 119 
 
 Fig. 35. Hookworm case of average severity in boy 120 
 
 Fig. 36. Same subject as Fig. 35 — Slight edema of face and ex- 
 
 pre^ion of illness 121 
 
 Fig. 37. Seven-year old girl with hookworm disease 122 
 
 Fig. 38. Hookworm case of average severity in girl 123 
 
 Fig. 39. Hookworm case of severe nature in boy 14 years old . . 125 
 
 Fig. 40. Hookworm case of severe nature in boy 16 years old . . 127 
 
 Fig. 41. Hookworm subject 22 years old 128 
 
 Fig. 42. Side view of Fig. 41 129 
 
 Fig. 43. Rontgenogram of hand of hookworm subject shown in Fig. 41 130 
 
 Fig. 44. Rontgenogram of hand of normal man 19 years old . . 131 
 
 Fig. 45. Diluted feces on slide for microscopic examination . . 159 
 
 Fig. 46. Microscopic appearance of feces 175 
 
 Fig. 47. Preparation made by Bass' method from feces .... 176 
 
 Fig. 48. Sanitary privy 196 
 
 Fig. 49. Sanitary privy 197 
 
HOOKWOEM DISEASE. 
 
 CHAPTER I. 
 DEFINITION. 
 
 Hookworm disease is due to certain species of hookworm 
 (ankylostoma duodenale, sometimes called uncinaria duo- 
 denalis, and necator Americanus) which live as parasites 
 in the small intestine. It occurs especially in warm 
 countries and in certain regions in temperate latitudes 
 where the climate in the summer, or other features — such 
 as warm mines — offer favorable conditions; chiefly in 
 persons who come in contact with damp earth, or with 
 water containing larvae of the parasites. It is character- 
 ized by the discharge of the ova of the worms with the 
 feces; by a progressive anemia, weakness, impaired de- 
 velopment in young subjects, and by various symptoms on 
 the part of the circulatory, digestive, and nervous systems, 
 in varying degrees and combinations; occasionally fatal, 
 it is capable of cure by removal of the parasites and of pre- 
 vention by hygienic measures. 
 
 The term ''hookworm carrier" is applied to persons in 
 whom hookworms live as parasites, but who, either from 
 small number of worms, from race immunity, or other 
 causes, do not develop obvious symptoms. 
 
 The importance of this class in the dissemination of the 
 disease is very great, and will be considered in the follow- 
 ing pages. 
 
 17 
 
18 HOOKWORM DISEASE. 
 
 Synonyms. 
 
 Ankylostomiasis ; ancliylostomiasis ; ankylostomasie 
 (French). 
 
 Anchilo^tomanemia ( Italian ) . 
 
 Ankylostomo-ana?mia (Latin) . 
 
 Ankylostomen-Krankheit (German). 
 
 Anquilostomiasis (Spanish). 
 
 Uncinariasis. 
 
 Dochmiosis. 
 
 Egyptian or tropical chlorosis. 
 
 Tunnelworker's anemia; tmmel disease; tnnnel anemia. 
 
 St. Gothard tunnel disease. 
 
 Brickmaker's anemia. 
 
 Mountain cachexia; mountain anemia. 
 
 Miner's anemia; miner's cachexia; anemie d'Anzin. 
 
 Anemie des pays chauds; anemia of Ceylon; Porto Eican 
 anemia. 
 
 Anemia intertropicalis. 
 
 Hypoaemia intertropicalis. 
 
 Malarial anemia. 
 
 Cachexia Africana; cachexia Americana-; cachexie 
 aqueuse. 
 
 Mai d'estomac (Pere Labat. 174:2). 
 
 Mai de cceur. 
 
 Geophagia (in part). 
 
 Allotriophagia (in part). 
 
 Dirt eating (in part). 
 
 Xegro consumption. 
 
 Eihagan (in Eg}7)t the "yellows," Sandwitli). 
 
 Opilacao (Portuguese). 
 
 Amerellao (i. e., "icterus"). 
 
 Cangagao (i. e., "tired feeling"). 
 
 Pica (in part). 
 
DEFINITION. 19 
 
 Malnutrition (in part). 
 Tun-tun. 
 
 The synonyms of liookwoim disease indicate the wide 
 range of symptoms, as well as the extensive geographic dis- 
 tribution, as shown by the diversity of languages. 
 
 Historical. 
 
 The efforts to interpret certain statements in the Ebers 
 papyrus (1550 B. C.) as proof of the knowledge of hook- 
 worm disease on the part of the ancient Egyptians are 
 purely fanciful. We may admit that the disease occurred 
 in Egypt then as it does nov/, and we may also accept the 
 ingenious suggestion of Sambon that its suspecteid causa- 
 tion was related to the veneration of the dung beetle, the 
 sacred scarab., by the Egyj)tians. But even if the symptom 
 picture was clearly recognized then, and even if the exist- 
 ence of the parasites was known, no information came down 
 to assist later generations in the recognition, prevention, 
 and treatment of the disease. 
 
 The history of hookworm disease is identical, as we now 
 know, with that of cases described in various tropical coun- 
 tries during three centuries — viz., Piso in Brazil (1648), 
 Father Labat in Guadeloupe (1748), Bryon Edwards in 
 Jamaica (1799), under various names as given in the list 
 of synonyms, and characterized by severe abdominal symp- 
 toms, anemia, dropsy, and weakness, often causing death, 
 chiefly among negro slaves, but also affecting other classes 
 of the population. At the time the true nature of the con- 
 ditions described was not understood and often wholly mis- 
 interpreted, and the misinterpretation continued to a recent 
 period. This is particularly true as regards the supposed 
 relation of malaria to the anemia, and hardly less so to the 
 relation of dirt eating, warm climates, and poverty. 
 
20 HOOKWORM DISEASE. 
 
 The discovery of the first hookworms in 1782 and 1789 
 had no influence on clinical study. 
 
 Certain diseases of miners in temperate latitudes, de- 
 scribed by older writers, can also be explained now by hook- 
 worm infection. Anemia was a striking symptom, and the 
 "miner's anemia" sometimes occurred in epidemics. In 
 1786 such an epidemic broke out in Schemnitz in Hungary, 
 and more than 1,200 miners were affected. There were sim- 
 ilar epidemics between 1802 and 1820 in the French mines 
 of Anzin, Fresnes, Vieux-Conde, Avize, Escarpelle, and 
 Graissesac. In 1875 the Medical Society of the Loire Basin 
 investigated the epidemic anemia. Sporadic cases were 
 observed and reported in Hungary and Bohemia. Ham- 
 merschmid noted that the disease differed from ordinary 
 anemia or chlorosis, that it represented a disease sui generis , 
 and that the explanation by the mine climate or vitiated air 
 was not satisfactory. 
 
 In 1838 Dubini, in Milan, found what he thought were 
 previously undescribed worms in the intestine of a woman 
 dead of pneumonia. Four years later he found some more 
 worms of the same kind in the body of a woman dead of 
 hydrothorax, and on a third occasion in the body of a man 
 dead of jaundice. In these three cases he saw only female 
 worms, but in another case he discovered males, and later 
 found similar worms in many subjects, either free in the 
 duodenum and jejunum, or hanging on to the mucosa by 
 their mouths. On the whole, he found them in at least 20 
 percent of bodies examined, and sometimes in company 
 with other worms. He thought the worms not without 
 effect on the body, though not causing special accidents; 
 that their seat was especially in the duodenum or upper 
 half of the jejunum; that an unusual amount of mucus was 
 essential for their existence; that the mucosa in the parts 
 affected was either normal, or injected, or punctate, red or 
 
DEFINITION. 21 
 
 black, and tliat the parasites occurred especially in cach- 
 ectic, emaciated persons, ultimately dying from diarrhea 
 and dropsy. The late discovery of the worms he attributed 
 to the failure of earlier observers to examine the intestinal 
 mucosa without washing the adherent mucus away with 
 water. He described the parasites accurately as small, 
 bent, partly transparent in the fore part, partly yellowish, 
 reddish, or brown worms, with a dark elevated point in the 
 middle, and the stomach filled with black material. He 
 gave a clear description and pictures of the microscopic 
 features, especially the rounded mouth with four curved 
 booklets rising from conical elevations, the flask-shaped 
 esophagus, the blunt tail of the female, the fan-like tail of 
 the male inclosing the genitalia. He proposed the name 
 agchylostoma — from ay/Mo^^ bent, and Troim, mouth. The 
 other details do not seem necessary to cite now.^ 
 
 Though Dubini thought he had discovered a new worm, 
 he had been anticipated to a certain extent. In 1782 Goeze 
 discovered some worms in the intestine of a badger (Meles 
 taxus). Although he gave it the name ascaris criniformis 
 (on account of its hair-shape), he suspected it belonged to a 
 different genus from the ordinary ascaris. He saw the 
 membranous expansion of the tail of the male, and in it two 
 rib-like structures, which he called hooks. 
 
 In 1789 Frolich found similar worms in the intestines of 
 foxes. He also observed the membranous expansion and 
 hooks, and proposed the name hookworm (Haakenwurm) 
 or uncinaria for the genus. The fact that other members 
 of the family strongylidse possess similar ''hooks" in the 
 bursa does not interfere with the retention of the name. 
 
 Dubini, besides describing the caudal hooks, noted the 
 hook-like teeth and the bent shape of the body. As Stiles 
 
 1 Dubini was ill advised in the construction of the new word. In trans- 
 lating from the Greek he should have changed the v to n and the k to c for 
 Italian usage. In other languages the < would be c, ch, or k. 
 
22 HOOKWORM DISEASE. 
 
 well points out, the feature that led to the common name 
 was the result of a misinterpretation; the "hooks" in the 
 mouth are not present in all species, and the curvature of 
 the body is not always distinct, hut nevertheless the com- 
 mon name is likely to be retained by reason of the rules now 
 followed in zoologic nomenclature. 
 
 Von Siebold (1845) gave the parasites a place in zoology 
 among the strongylidai. Castiglioni and Pruner soon after 
 described the occurrence of the worms in the bodies of 
 dropsical and cachectic individuals, but, like Dubini, did 
 not realize the actual relations. Bilharz (1853) and Gries- 
 inger (1854) in Egypt recognized the relation of the para- 
 sites to the extremely prevalent "Egyptian chlorosis," the 
 cause of more than one-quarter of all deaths in that country. 
 But although Griesinger especially was emphatic in his 
 statements, practically no attention was paid to them for 
 more than ten years. In 1866 Wucherer, in Bahia, again 
 called attention to the subject, based upon its frequency 
 among negro slaves in Brazil. His statements were con- 
 firmed by other Brazilian physicians, and gradually reports 
 began to appear from various other tropical regions. In 
 Italy many additions to the knowledge of the occurrence of 
 hookworms were made, the most important being the sug- 
 gestion by Paletti and Maliverria (1877 — 1878) that the 
 anemia of brick workers, long known in Italy, was caused 
 by hookworm, and the discovery by Grassi (1877) and 
 Parona of the diagnostic value of the ova in the feces of 
 hookworm subjects. 
 
 The migratory habits of Italian laborers led to a striking 
 epidemic of hookworm disease. In the digging of the St. 
 Gothard tunnel (1879 — 1880) a large number of workmen 
 showed signs of intense anemia. Perroncito and Toncato, 
 Bozzolo, rV)loniiatti, Parona, Sonderegger, and others 
 showed that not only did the parasites occur in the anemic 
 
DEFINITION. 23 
 
 cases, sometimes in enormons numbers, but that they were 
 often the only discoverable canses of disease. These re- 
 sults were confirmed in other places, notably in Switzer- 
 land, liy Immermann and others, and in Freiburg by Banm- 
 ler in tunnel workmen. 
 
 These discoveries led to - the proof that the so-called 
 ''miners' anemia," ascribed to deprivation of light and air, 
 in the mines of France and Hnngar}^ was also due to hook- 
 worms, and in the mines of Sardinia measures to check the 
 development and spread of hookworm eggs were followed 
 by diminution in the number of cases of anemia. 
 
 The conclusions regarding miners' anemia were rapidly 
 extended to other countries. In 1869 Leuckhart thought 
 ankylostomiasis did not occur north of the Alps. In 1882 
 it was discovered in brick workers in the Ehine country, 
 who had no relation to Italian workmen. In fact, the 
 anemia of the brick workers in the Ehineland and Prussia 
 had been recognized, but not correctly explained, for more 
 than twenty years before. The prevalence of hookworm 
 disease in the region of Cologne gave Leichtenstern oppor- 
 tunities for making some of the most important contribu- 
 tions to the subject, including the discovery of the disease 
 among the Belgian miners ("Walloons"), who worked in 
 the coal mines of Mons, Liege, etc., in winter and in the 
 Rhenish brick fields in summer. 
 
 It does not seem necessary to describe the discovery of 
 hookworms in various parts of the tropics. The present 
 conditions there will be mentioned in the next chapter. 
 Suffice it to say that the evidence points to the tropics, and 
 especially Africa, as the original home of the disease. It 
 is not easy to trace the routes the parasites followed to 
 Europe, but it is liiuhly proliable they entered from Egypt 
 by way of Italy or Hungary, and spread from there to Swit 
 zerland, the Rhine, and Belgium, from Hungary to Ger- 
 many, and from various parts of the tropics to Cornwall, 
 
-^ HOOKWORM DISEASE. 
 
 The history of hookworm disease in the United States is 
 of great interest. From an early period reports were pub- 
 lished on the dirt eating and anemia of negroes in several 
 southern states, and Hirsch (1883) and other European 
 writers based upon these reports the statements that hook- 
 worm disease existed, "although only in slight extent, 
 among the negro population of some parts of the southern 
 United States." That Hirsch does not deserve particular 
 credit for the accuracy of his statement appears from the 
 fact that he thought there was little hookworm disease in 
 Asia. 
 
 It is worth while recalling some of the early American 
 accounts, for from these it is obvious that the disease ex- 
 isted, but the accurate diagnosis was not to be expected at 
 the time, as the presence of hookworms — in many cases 
 even intestinal worms in general — was not suspected, and 
 the significance of the disease was wholly missed. 
 
 Stiles quotes Joseph Pitt (1808) as the earliest author 
 he has found to refer to the disease in this country. Pitt 
 described dirt eating among the poor white people and 
 negroes, and thought it was due to deficiency of nourish- 
 ment. The author most frequently quoted abroad is 
 Chabert (Eeflexions medicales sur la maladie Spasmodico- 
 lyperienne des Pays Chauds, vulgairement appelee Fievre 
 Jaune. J. L. Chabert, Dr. en med. de la Fac. de Mont- 
 pellier, a. m. ord. des arm. Franc, etc., Nouvelle-Orleans, 
 de Pimp, de PAmi des lois. 1821). He referred to dirt eat- 
 ing as a habit contracted by many slaves, and described the 
 resulting lesions and the means of recognizing and curing 
 them. His words are worth quoting more fully (p. 188 
 etseq.): ''For most of the negroes, doing nothing is the 
 supreme bliss. Some of them carry love of idleness to such 
 a point that they employ, in order to escape work, every 
 means suggested by sloth, notwithstanding the certainty 
 
DEFINITION. 25 
 
 of injury to health. Among these, earth, the internal use 
 of which causes a species of poisoning, is most common of 
 all, if I may judge by my own practice. Under the influence 
 of this bizarre food there develops in those who use it symp- 
 toms and accidents like those produced by poison in the 
 living organism — i. e., yellow complexion, dry scaly skin, 
 puffy face, swelling of the legs, engorgement of the abdom- 
 inal viscera, atrophy of the muscles, palpitation, dyspnea, 
 and at last obvious signs of aneurism (i. e., dilatation) of 
 the heart from thinning of its walls, which, when well 
 marked, always ends the case." 
 
 Chabert made an autopsy in the case of a dirt eater, but 
 described no worms, and thought a perforation he found in 
 the stomach was due to an old ulcer. It can hardly be 
 doubted that he was dealing with genuine cases of hook- 
 worm disease, but wholly unaware of the fact. 
 
 Geddings, in 1834, doubtless saw cases in the anemic 
 and cachectic ''sand lappers" of Carolina. Little, in 1845, 
 gave an interesting account of dirt eaters in Florida, in 
 which the descriptions of the subjects leave no doubt they 
 had hookworm disease. Sir Charles Lyell (1849) also made 
 observations during his travels in the South, and noted 
 cases of dirt eating in Alabama. 
 
 James B. Duncan (Eeport on Topography, Climate, and 
 Disease of the Parish of St. Mary, La., Southern Medical 
 Reports, edited by E. D. Fenner, New Orleans and New 
 York, vol. 1, p. 190, 1849) gave a very accurate description 
 of cases. He speaks of a very common anemia among 
 negroes on plantations, "very often attributed, and perhaps 
 justly so, to the pernicious habit of dirt eating.'' The 
 proportion of severe cases was not large. Duncan says (p. 
 194): ''Almost every large plantation has three or four, 
 and sometimes more. Until the vital powers of the system 
 are beginning to be undermined, no marked symptoms of 
 
26 HOOKWORM DISEASE. 
 
 the disease being visible to the ej^e of the planter, they are 
 generally suspected of laziness or malingering. After this 
 condition has existed for some time, the skin presents a 
 paler hue than natural, or, if the subject is a mulatto, an 
 ashy white; the lips, tongue, lining membrane of the mouth, 
 and palms of the hands white, lacking the reddish tinge of 
 health; the legs edematous; abdomen distended; pulse full, 
 soft, and frequent; action of the heart violent; if blood is 
 drawn, it is pale and watery; respiration on the slightest 
 exertion anxious and hurried; in fine, all the symptoms that 
 characterize chlorosis in females. We find this condition 
 of things in subjects of both sexes. Many of these cases 
 are, doubtless, produced and aggravated by the deleterious 
 habit of dirt eating. But I never heard a negro admit that 
 he was addicted to the habit. Some admit that formerly, 
 3^ears ago, they ate dirt, but do not now; and others, trusty, 
 truth-telling negroes on all other subjects, on this will lie 
 most pertinaciously to the last, unless detected in the act." 
 Duncan thought that in many cases "dirt eating was a 
 symptom only of a diseased condition of the digestive 
 organs and of the system generally. With them dirt eating 
 is the same propensity to which white females resort to re- 
 lieve a disordered acid condition of the stomach by eating- 
 quantities of chalk, magnesia, etc. This condition of sys- 
 tem is often, in my opinion, produced by a deficiency of 
 suitable nutriment. The diet of negroes on most planta- 
 tions being mostly salt pork, corn bread, and molasses — 
 rarely eating fresh meat and vegetables — a condition of the 
 system is thus produced closely allied to scurvy." (He 
 noted spongy gums, and functional and organic disease of 
 the heart.) Duncan reported cures by the use of nutritious 
 foods, fresh meats, vegetables, and greens, porter and wine, 
 iron, stomaoliics, and tonics, laxatives when indicated, and 
 out-door exercise. He throws a curious light on the seri- 
 
DEFINITION. 27 
 
 ousness of the condition so briefly described by speaking oi: 
 the use of tin masks, iron gags, and chaining to the floor to 
 correct dirt eating. ''By nsing these means," he says, "it 
 is true the habit can not be indulged in, but the cause that 
 produced the propensity still exists. Restore the healthy 
 tone of the system, invigorate the subject, put rich blood 
 into his veins, clothe him well, feed him well, and do not 
 overtask him; arouse his feelings of pride, teach him to feel 
 that he is a reasonable being, and in a majority of cases 
 success will attend our efforts, and we shall have the satis- 
 faction of rescuing a valuable servant from the grave." 
 
 It is impossible to tell how much of this belief was 
 founded on actual treatment. It may be that mild cases 
 then improved without direct causal treatment, but it is 
 difficult to imagine that reinfection did not occur. 
 
 Heusinger wrote an interesting work on dirt eating 
 (''Die sogenannte Geophagie ocler Tropische — besser, 
 Malaria — chlorose als Krankheit aller Lander und Klimate, 
 dargestellt von C. F. Heusinger, Cassel, 1852), but showed 
 great lack of critical insight. He asserted dirt eating was 
 common also in the region of the great lakes, based largely 
 on statements of Bartlett, Wood, and Drake. He properly 
 considered dirt eating a symptom and not a cause of disease. 
 
 Xone of these writers give the impression they were 
 dealing with a widespread disorder. This is probably due 
 to the fact that then, as now, many negroes were immune to 
 the severe effects of the infection, that the white population 
 was scattered and was relatively small, and many of the 
 whites probably escaped infection. None of the medical 
 writers we have consulted speak as if the disease was com- 
 municable, but we liave found a suggestive statement in the 
 account of an excellent lay writer, Mr. Thomas Affleck, of 
 Washington, Miss., author of the "Southern Eural Alma- 
 nac," who had been an extensive planter, and wrote an in 
 
-S HOOKWORM DISEASE. 
 
 teresting chapter for Fenner's "Southern Medical Ee- 
 ports" (vol. 2, p. 429—436, 1851) "On the Hygiene of Cot- 
 ton Plantations and the Management of Negro Slaves. ' ' He 
 confirms what others say of the diet: "The general allow- 
 ance of m^at being three and a half to four pounds per 
 week of sound mess pork, or its equivalent in bacon, to each 
 working hand over 10 years old, with bread, hominy, vege- 
 tables, etc., ad libitum. Fish and molasses are given occa- 
 sionally. Not nearly enough of vegetables are grown and 
 fed to negroes." He also said (p. 433): "Dirt eating is 
 frequent among young negroes, and always kills them if not 
 cured. The constant use of molasses is said to induce it, 
 but I can not say how correctly. Those under the best care 
 are liable to it. Seems to be occasioned by a morbid state 
 of the stomach, and should be so treated. One dirt eater 
 upon a plantation will infect tJie^ivJiole. Mostly infected at 
 from two to ten year's. Say, one child in forty eats dirt." 
 [Italics ours. — D. and B.] 
 
 On the whole, the reports from the South in the first half 
 of the nineteenth century could not easily convince one that 
 ankylostomiasis existed there, and in the latter half, for a 
 long time, no accurate observations seem to have been 
 made. Moreover, during this part malaria acquired a new 
 interest and importance, so that its occurrence was easily 
 exaggerated. 
 
 In 1886 Dr. Joseph Leidy made an interesting remark 
 apropos of some specimens from anemic cats sent by Bel- 
 field, of Chicago. He noted the worms had the same struc- 
 ture of mouth as had ankylostomum duodenale; thought 
 they might be able to infect man, and be one of the previ- 
 ously unrecognized causes of pernicious anemia. This idea 
 had been expressed before, and was then repeated more or 
 less distinctly by various writers for the next ten years. 
 In 1891 Dolley called the attention of American physicians, 
 
DEFINITION. 29 
 
 especially those of the southern states, to the "fact," an 
 per Hirsch, that ankylostomiasis was long since reported in 
 the South. 
 
 In 1893 Blickhahn, of St. Louis, reported a case in the 
 person of a brickmaker from Oberhausen, near Essen, in 
 Westphalia. In 1897 Mohlau reported several cases in 
 Buffalo, and it seemed that some of the patients became 
 infected in this country from Italian or Polish immigrants. 
 Through the courtesy of Dr. Joseph Collins, Dock was able 
 to cite a case observed in New York by Dr. Joseph Frankel 
 in the person of a foreigner who had long lived in the 
 United States, and seemed to have acquired the disease 
 here, "perhaps handling hides." (Article on Anchylosto- 
 miasis, Loomis and Thompson's System of Practical Medi- 
 cine, vol. 3, p. 337 et seq.;'1898. ) 
 
 To this transition period belong the reports of Herff 
 (1894), who found worms in a Mexican and asserted their 
 existence in this country; Dabney (1898) and Tebault 
 (1899), who both found them in New Orleans; Gray (1901), 
 who found them in Richmond, Va.; Clay tor (1901) in Wash- 
 ington, D. C; and Boston, Allyn, and Behrend (1901) in 
 Italians in Philadelphia; Dyer in St. Louis; and Hall and 
 Yates in Baltimore. 
 
 The era of productive discovery begai] at the same time. 
 Allen J. Smith, in 1895, found ova of hoo kworm in the feces 
 in a water closet in Galveston, Texas, bul could not fix upon 
 the individual from whom they were derived. On Feb- 
 ruary 17, 1901, Dr. Smith recognized ova in the stools of a 
 sailor born in Melbourne, Australia, who first became ill 
 while acting as overseer of a plantation in southern Mexico, 
 where there was an epidemic disease of a very fatal type, 
 which led to pallor, emaciation, and dropsy. The patient 
 also had amebic dysentery. Dr. Smith recognized differ- 
 ences in the worms expelled from the patient as compared 
 
30 HOOKWOKM DISEASE. 
 
 w 
 
 witli ankylo stoma dnodenale, and thought they might be 
 uncinaria stenocephala of dogs. Q^he dogs in the labora- 
 tory, however, had only uncinaria canina, so that compari- 
 sons conld not be made. Later, Charles Wardell Stiles 
 showed the existence of a new si^ecies in man, and Dr. 
 Smith was able to demonstrate that his patient had both 
 old world and new world hookworms. Stiles had for 
 years pointed ont the probability of the frequent occur- 
 rence of hookworm in America. In 1901 he published his 
 views {Texas Medical Neivs, July), stating that hookworm 
 in man must be more or less widespread in the United 
 States. Soon after that. Smith's case was i3ublished by 
 Dr. Charlotte Schaeffer, who also mentioned the finding 
 of ova in the feces of two (later increased to eight) out 
 of eighty-odd medical students in the Galveston school. 
 Stiles (1903) shows clearly the great value of Smith's work 
 in the development of our knowledge of hookworm in the 
 United States. "To the clinician it did not mean ver}^ 
 much, since no record existed that the students exhibited 
 any very severe symptoms. To the zoologist, however, it 
 meant a practical demonstration that uncinariasis was more 
 or less common in the South. Here were eight students in 
 a city (Galveston); the chances that the infection took 
 IDlace in Galveston did not seem very great; as the students 
 came from different places, the infection must be more or 
 less widespread; and, since light cases occurred among 
 medical students, heavier infections must naturally occur 
 among persons who come more regularly in contact with 
 the dirt." 
 
 From a study of the worms in the case of A. J. Smith and 
 Claytor, and some from Porto Rico, Stiles was able to show 
 that they were not uncinaria stenocephala or any other 
 known species, and on May 10, 1902, he described a new 
 species, uncinaria Americana. In a paper piiblisliod in the 
 
DEFINITION. 31 
 
 Eigliteentli Annual Eeport of the Bureau of Animal Indus- 
 try (September 25, 1902) lie declared there was an endemic 
 of hookworm in the United States which had been generally 
 overlooked. In the months between the statements both 
 Claude A. Smith and H. F. Harris had reported cases in 
 Georgia, and a little later Harris made the important asser- 
 tion that the greater number of cases of anemia in certain 
 southern states were due, not to malaria, as universally be- 
 lieved, but to uncinariasis, and that it was "the most com- 
 mon of all the more serious diseases of the entire South. 
 In no other disease does the victim suffer so long, in no 
 other condition is he for such a period a menace to those 
 about him, and in no other malady of such gravity is treat- 
 ment so rapidly and surely successful." W. F. Arnold 
 complains, with justice, that the subject was neglected after 
 the striking announcements just described. Some of the 
 subsequent communications will be referred to in the next 
 chapter. 
 
 The work of Bailey K. Ashford and his colleagues on 
 hookworm disease in Porto Rico furnishes one of the most 
 interesting and instructive chapters in the history of en- 
 demic disease. 
 
 In 1899, soon after a destructive hurricane in the island, 
 Ashford established a hospital for the care of those who 
 could not be accommodated in the hospital at Ponce, "Ful- 
 ly three-fourths of those admitted were suffering from 
 anemia, which was then believed to be due to faulty diet, 
 but, as iron, arsenic, and full diet failed to cure, it was 
 attributed to malaria, climate, lack of hygiene, etc., all of 
 which proved upon investigation to be inadequate." In 
 studying the blood as an aid to exact diagnosis, Ashford 
 was struck by the high eosinophilia. He suspected ankyl- 
 ostoma, and "examination of feces made the suspicion a 
 certaintv." R. Blanch ard had concluded that the disease 
 
32 HOOKWORM DISEASE. 
 
 was present in Porto Rico, but no exact observations had 
 been published and no immediate general attention fol- 
 lowed Ashford's first report, though it had official recog- 
 nition. 
 
 In 1902 Drs. Ashford and King made a further study of 
 ankylostomiasis, and reported on one hundred cases in 
 1903. {American Medicine, September 5 and 12.) This 
 aroused much interest, not only in medical circles, but also 
 in the administration of the island. In 1904 a commission 
 was formed for the study and treatment of anemia, consist- 
 ing of Dr. Ashford, Captain and Assistant Surgeon, U. S. 
 A.; Dr. W. W. King, Past Assistant Surgeon, Public Health 
 and Marine Hospital Service; and Dr. Pedro Grutierrez, 
 health officer of Bayamon. With comparatively slender 
 resources this commission carried out an immense cam- 
 paign of diagnosis, treatment, and scientific research. It 
 proved beyond question that the anemia so prevalent in the 
 island was only a symptom of uncinariasis, which affected 
 the rural population to the extent of 90 percent. Still more, 
 it published most valuable reports upon the work, and 
 upon hookworm disease in general. (Report of the Com- 
 mission for the Study and Treatment of '' Anemia" in Porto 
 Rico. San Juan, P. R., 1904 et seq.) 
 
 Even before the time the parasites were receiving so 
 much attention in America, Looss (1898), in Cairo, Egypt, 
 made the important discovery of the penetration of the 
 skin by the larvae, a discovery that has made the pathology 
 and especially the prevention of the disease much more 
 exact than it was before. This part of the history will be 
 discussed in connection with the ''Modes of Infection." 
 
CHAPTER II. 
 
 DISTRIBUTION AND ECONOMIC IMPORTANCE. 
 
 Hookworms have an extensive range, being fonnd in all 
 parts of the tropics, where they may be said with truth to 
 be the greatest enemies of the human race, and in many 
 countries with subtropical climate, as well as in some 
 regions properly classed as temperate. The extreme range 
 of latitude is from 51° N., or the latitude of Belgium, to 
 nearly 40° S. Altogether it is one of the commonest dis- 
 orders, and in the tropics one of the most important. It is 
 in all j)robability the chief cause of the so-called tropical 
 anemia, which has been looked upon as due to climatic con- 
 ditions rather than disease factors in the usual sense. 
 
 In Europe the disease has been found chiefly in Belgium, 
 France, England, Germany, Hungary, the Balkan peninsula, 
 and Italy. In Italy, Sicily, and Sardinia, where ankylos- 
 tonia was first discovered as a human parasite, it occurs in 
 various parts and sometimes in great intensity. Previtera 
 found 75 percent of miners infected in Catania, in a district 
 (Muglia) where almost 100 percent had oxyuris. In Spain 
 it occurs in miners, and probably other classes also. 
 
 In Austria, Hungary, the plains of the Danube and 
 Theiss, Servia, and Bulgaria it occurs, especially in the 
 mining regions, but also elsewhere and in other classes of 
 the population. In some parts of Hungary up to 95 per- 
 cent of miners have been found infected, but, owing to 
 precautions taken and treatment, this has been reduced to 
 about 30 percent. Many are so severely affected that they 
 are unable to work on account of swelling of the feet and 
 shortness of breath. The great lieat in many Hungarian 
 
 33 
 
34 HOOKWOEM DISEASE. 
 
 mines, up to 104° — 113° F., favors the development of the 
 larvae. 
 
 In Belgium the disease has been very prevalent in the 
 last quarter of a century. The parasites were first discov- 
 ered in Belgium by Firket in 1884, but, as said before, the 
 disease probably existed among miners long before that. 
 It was reintroduced by miners from St. Gothard and be- 
 came epidemic about 1884, but subsided apparently, only 
 to break out afresh in a most virulent form, with a high 
 death rate. Little attention was paid at first, but, after it 
 became serious in the mining districts of Liege, Mons, and 
 Charleroi, active measures for its repression were begun by 
 the government. At the International Congress of Miners 
 in 1903 it was said that 10,000 miners in the Liege basin 
 were infected. So great was the extent that sick benefit 
 societies had to refuse membership to men working in some 
 mines, the proportion of affected workmen being from 25 to 
 75 percent, with in some places a very high death rate. 
 
 In France the miners in many localities are also seriously 
 infected, especially in Anzin, Valenciennes, Lyons, and St. 
 Etienne (2 percent), and the Loire basin (5 percent). 
 
 In the Dolcoath mines in Cornwall, England, where a 
 severe form of anemia had been noted in the miners for 
 about eight years previousl}'^, Boycott and Haldane, in Octo- 
 ber, 1902, showed its occurrence, and traced it to miners 
 who had lived in the tropics. 
 
 Stockman (1903) reported the case of an infected miner 
 in Scotland who had been in India. 
 
 In Germany it is especially in the Ehineland and West- 
 phalia that the parasites abound, but many cases occur in 
 the vicinity of Berlin and a few cases have been found in 
 Saxony, introduced by Polish miners, and in Silesia. On 
 the Rhine, Cologne, Bonn, and Aix-la-Chapelle, and in 
 Westphalia, Essen, Dortmund, and Bochum are important 
 foci. 
 
DISTEIEUTION. 35 
 
 The possibilities for harm of the disease, outside of the 
 tropics, are well illustrated by the conditions in the West- 
 phalian mines. Infection there was brought about by Ital- 
 ian, Hungarian, and Polish miners, and was favored by 
 certain factors. One was the rapid increase of the mining 
 industry, which led to the importation of 20,000 new miners 
 in a single year. (In the year 1902 there were 289 mines, 
 with 256,000 miners.) But the most important cause was 
 the introduction of spraying the mines with water for the 
 purpose of preventing explosions of coal dust. On Feb- 
 ruary 17, 1898, there was a tremendous explosion. On 
 July 12, 1898, regulations for spraying were passed, and 
 put into execution from July 1, 1899, to January 1, 1900. 
 The effect of this can be seen in the following table after 
 Oliver, a slight decline being followed by a notable increase: 
 
 ,^ Number of Number Per 
 
 infected mines, of cases. fO.OUO. 
 
 1896 15 107 6.4 
 
 1897 31 113 6.2 
 
 1898 23 99 4.9 
 
 1899 26 94 4.4 
 
 1900 40 275 11.7 
 
 1901 63 1,030 40.6 
 
 1902 66 1,355 52.9 
 
 In 1901, out of 63 infected mines, 57 of them were watered, 
 and showed 1,021 cases. The other 6 infected mines were 
 not watered, and gave only 9 cases. At one time in West- 
 phalia there have been 25,000 cases of hookworm disease. 
 
 In Africa, Egypt (90 percent in Cairo, 20 — 30 percent in 
 other places), and the Mediterranean countries, the east and 
 west coasts to the Cape, Uganda, Mombosa, Mozambique, 
 Zanzibar, Madagascar, Mauritius, and the Comoro Islands 
 are all infected, but, as Zinn and Jacoby first pointed out, 
 the African negro races are not so likely to show severe 
 symptoms as many other races. In Cameroon, Kiilz found 
 
'S6 HOOKWORM DISEASE. 
 
 70 percent of the population affected, and, although in 
 adults the symptoms, especially anemia, were less marked 
 than in children, many even of the former had severe pal- 
 pitation of the heart. The less civilized the tribe the 
 greater ^^^ the extent of the infection. In Kimberly, 
 Mathias discovered the disease in miners in 1896. In the 
 Transvaal, Posnett found 32 percent of native miners af- 
 fected. 
 
 In Madeira, Goldschmidt discovered two foci, apparently 
 due to returned emigrants from Brazil. The infection, 
 severe at first, became milder. 
 
 In Asia there are many severely infected areas, including 
 most of India, where it was first found in 1879 by McCon- 
 nell (Calcutta), China, Cochin China, Burmah, Siam, Cey- 
 lon, the Malay Archipelago, Java, Borneo, Formosa, and 
 Japan. In Japan the parasites were first found by Baelz 
 in 1877. The infection is very prevalent among country 
 peoi)le, but as a rule not severe. Cases have been found in 
 Siberia, derived from the Japanese. In the tea gardeners 
 of Assam, Dobson found ova in the stools of 454 out of 
 574 immigrants from all parts of India. 
 
 Manila and the Philippines, Guam, Australia, New 
 Guinea, Fiji, and the Sandwich Islands are also severely 
 affected. In Manila, Strong found 52 percent infected 
 among 4,016 Philippine prisoners. Among the returned 
 soldiers are many cases, most of whom, fortunately, in re- 
 turning to the United States live in places not favorable for 
 the develoj)ment of the larvae. 
 
 In South America the disease is still very extensive, es- 
 pecially in Brazil, where Wucherer and Lutz made such im- 
 portant observations. It occurs also in other parts of the 
 continent, as far as Argentine, and in the islands along the 
 coast. Daniels found parasites in 52 percent of autopsies 
 in Demerara. Law (1908) found 45 percent of the popula- 
 tion infected in British Guinea. 
 
DISTRIBUTION. 37 
 
 In Mexico, Manuel discovered the worms in 1902 in the 
 southern states of the republic. Alvarez found none in the 
 north (Sonora), but some in lower California and Sinaloa. 
 
 In Central America the disease is common in all parts, 
 especially in the coast countries and the foot hills. Accord- 
 ing to Prowe, legends tell of its existence — symptomatic, 
 of course — in Guatemala and San Salvador for centuries. 
 
 In all parts of the Antilles the disease is present. In 
 Cuba it was first shown to exist by Agramonte (1902). 
 Guiteras finds it less prevalent in Cuba than the Porto Rico 
 Commission found it in the latter island. 
 
 In Panama, in the pathological laboratory of the Ancon 
 Hospital, Whipple found, in autopsies, old world hookworm 
 in 17 percent, the new world variety in 21 percent of bodies. 
 In about half the cases of the latter the old worm was 
 present, but necator Americanus predominated in all heavy 
 infections. Brem, in Panama, found hookworms in 36.1 
 percent of 277 patients from various parts of the tropics. 
 
 United States. 
 
 No systematic investigation has been made of the terri- 
 tory known to be infected. Dr. C. W. Stiles has made sev- 
 eral reconnoissances, including a large part of the South. 
 These have stimulated many valuable observations by 
 physicians in various parts of the country. The extent and 
 the intensity of the infection in the whole population can 
 be surmised from the data present, but a systematic and 
 extensive search is very much needed. 
 
 It is clear that the country from Virginia, at the Potomac 
 river, to Florida and Texas is infected. In Virginia, Clay- 
 tor's early case furnished Stiles with the first specimen of 
 uncinaria Americana. Bagly (1910) believes there are 80 
 percent of infected work people in the cotton mills. 
 
o» HOOKWOEM DISEASE. 
 
 In North Carolina the disease is even more frequent, as 
 shown by the valuable work of Nicholson and Rankin 
 (1904). They found that 37 percent of 140 students of 
 Wake Forest University were infected, usually in a mild 
 form. Semetimes every man from a given district was 
 infected. 
 
 In South Carolina the conditions are doubtless equally 
 serious, as shown by Stiles' investigation, but extensive 
 observations are lacking. 
 
 In Georgia the assertion of Harris that the disease is one 
 of the commonest of the serious diseases was found justified 
 by C. A. Smith (Atlanta), Warfield (Savannah), A. G. Fort, 
 and many others. 
 
 In Florida extensive observations do not yet exist, but 
 the disease is frequent, as Stiles pointed out in his early 
 survey. Kinyoun (1908) found very many hookworm car- 
 riers, especially among negroes. At present active efforts 
 are being made for repression of the disease. 
 
 In Alabama, Bondurant, of ]\robile (1903), first called at- 
 tention to the extent of the disease. Harrison, of Talledega 
 (1204), made an important addition to our knowledge. 
 Perry (1910) reports 15 to 20 percent in the white popula- 
 tion infected, and Cole and Winthrop {vide infra) show 
 even more. 
 
 In Mississippi, Bass found from his own observations and 
 those of correspondents that up to 50 percent of the popu- 
 lation were affected, and concluded that practically all the 
 rural population of the southern half of the state have or 
 have had the infection. 
 
 In Louisiana, Lemann and Guthrie called attention to the 
 importance of the disease in 1903, and many cases have 
 been observed since then, but no extensive series of cases 
 has been reported. The conditions in country localities are 
 doubtless al)ont the same as in adjacent states. Gage and 
 
DISTRIBUTION. 39 
 
 Bass have examined 90 students in the Tiilane University 
 who were living in the state; 42.4 percent of those from the 
 country, and 2.5 percent from the city were found infected, 
 or a total in the whole state of 20.7 percent of young male 
 adults were hookworm carriers. 
 
 In Arkansas, Deaderick found comparatively few cases, 
 and the same will probably hold good in Tennessee. 
 
 Texas is widely affected, as Allen J. Smith showed early. 
 Investigations are now being made by the State Board of 
 Health, and fully confirm the wide range and intensity of 
 the infection. 
 
 Valuable information appears in a report by Dr. Stiles 
 to the Bureau of Labor. (Annual Eeport of the Surgeon 
 General of the Public Health and Marine Hospital Service 
 of the United States for the fiscal year 1908, AYashington, 
 1909.) 
 
 The investigation shows that 12.67 percent of cotton mill 
 employees are hookworm suspects. The percentage varies 
 with sex and age. 
 
 ^ Percent 
 
 suspects. 
 
 Over 20 years 8.4 
 
 16 to 20 years 19.2 
 
 Under 16 years 27.2 
 
 Females 16.1 
 
 Males 15.2 
 
 Boys under 16 years 29.4 
 
 Girls under 16 years 18.7 
 
 Boys 16 to 20 years 20.7 
 
 Girls 16 to 20 years 18.1 
 
 Males over 20 years 5.8 
 
 Females over 20 years 13. 
 
 Interesting observations have been made on recruits in 
 the United States Army. Siler (1909), in an examination 
 of 105 recruits from the southern states, found 93 infected, 
 or 88.5 percent, and 85 percent in a total of 140 cases. 
 
 Chamberlain (1909) found 60 percent of infected men 
 among southern recruits. 
 
40 HOOKWORM DISEASE. 
 
 The observations of Gage and Bass on 296 university 
 students are interesting in comparison with those on re- 
 cruits, for they deal with young men of about the same age, 
 presumably equally free from obvious symptoms, probably 
 belonging-sto families in better circumstances than those of 
 the recruits, and not so much exposed to the danger of in- 
 fected soil. The figures are small, but no selection was 
 made. The number of worms recovered from the subjects 
 varied from 3 or 4 to 200, so that the men were worm carriers 
 of real danger under conditions favorable to the dissemina- 
 tion and development of the ova. 
 
 Locality. Positive. Negative. 
 
 Alabama 14 19 
 
 Arkansas 4 9 
 
 Florida 1 4 
 
 Georgia 7 7 
 
 Illinois 2 
 
 Kentucky 1 
 
 Louisiana, outsifie New Orleans 27 51 
 
 Louisiana, in New Orleans 1 39 
 
 Massacliusetts 1 
 
 Mississippi 14 38 
 
 Missouri 3 
 
 Oklahoma 1 3 
 
 Pennsylvania 1 
 
 South Carolina 3 
 
 Tennessee 2 6 
 
 Texas 7 7 
 
 Canada 1 
 
 Porto Rico 1 
 
 Roumania 1 
 
 Out of the subjects from the southern states outside of 
 New Orleans we get a percentage of infected students of 
 32.8. 
 
 Winthrop and Cole, in examining 66 Alabama medical 
 students, found 33, or 50 percent, infected. 
 
 Further facts bearing on the economic aspects of hook- 
 worm should be noted. Among the females of child-bear- 
 
DISTRIBUTION. 41 
 
 ing age, 13 to 18 percent are uuable properly to iioiirisli in- 
 fants. Of males of military age, 5.8 to 20.7 percent are rel- 
 atively inefficient. Among children of school age, 18.7 
 (females) to 29.1 (males) are miable properly to profit from 
 study. "Taking all the statistics together, 12.6 percent of 
 the mill population are affected with a disease which 
 materially inhibits their normal working powers, and hence 
 inhibits the economic development of the community in 
 which they live." 
 
 It should also be noted that in some of the mills the pro- 
 portion of hookworm cases is as high as 80 percent among 
 the children. 
 
 Stiles has also pointed out the part the negro has in the 
 perpetuation and spread of hookworm disease. Relatively 
 immune to the disease, the negro is an extensive worm 
 carrier, and is even more careless as regards soil pollution 
 than his white neighbor. 
 
 In general, the parasite found in old world cases is ankyl- 
 ostoma duodenale; that in America, necator Americanus; 
 but Leiper found the latter widely distributed in the tropics, 
 especially in Africa. It has been found in returned immi- 
 grants in Italy, from Brazil as well as from the United 
 States (Schifone), and also in other localities, but appar- 
 ently has not yet spread beyond the immigrants. Necator 
 Americanus has also been found in patients from various 
 parts of Asia, Ceylon, the Philippines, and Australia, in 
 the Hamburg Sailor Hospital (Eodenwaldt), and by Noc in 
 Cochin China. Looss found it in pygmies in Africa, and 
 Fiilleborn in Cameroon. Da Silva Pinto finds necator more 
 frequently in the state of Sao Paulo in Brazil than ankyl- 
 ostoma. Branch thinks necator may be the original and 
 more common tropical hookworm. The conditions of work 
 and travel at the present time are such as to cause even 
 greater mingling of the two species than occurs now. 
 
42 HOOKWORM DISEASE. 
 
 Climate. 
 
 Tlie chief factors in the existence of hookworm infection, 
 given the j)resence of the parasite, as by fresh importation, 
 are high temperature and moisture. The extent of the 
 disease in fhe tropics makes this clear, and the intensity of 
 the disease in the tropics even clearer. Outside the tropics, 
 mines offer the best conditions for the disease to exist. Xot 
 all mines are equally affected, even when miners carrying 
 worms are employed. In the mines of Pas-de-Calais, for 
 exami)le, Brehon found only two infected miners, and they 
 had come from a mine near Mons, in Belgium. The mines 
 at Pas-de-Calais have neither high temperature nor great 
 moisture. So also in Bohemia no cases were found until 
 1903, and since then only a few. But the mines are not 
 very deep and the temperature, accordingly, not very high. 
 Wainwright and Nichols (1904) made a large series of 
 observations in the anthracite coal mines of Pennsylvania, 
 but found hookworm in only one case. 
 
 Tenholt gives an instructive table showing the relation 
 of temperature in mines to infection in Westphalia. 
 
 TPinnpratiirp Number of Percentage 
 
 lempeiaiuie. workmen. of infected. 
 
 Below 17°C.=62.6°F. . , 36,033 0.6 
 
 17°— 20°C.=62.6°— 68°F 68,604 0.4 
 
 20°— 22°C.=68°— 71.6°F 43,710 2.5 
 
 22°— 25°C.=71.6°— 77°F 39,836 11.7 
 
 Above 2.5°C.=77°F 9,853 39.9 
 
 (The most favorable temperature for the development of 
 the larvge is from 25° to 35° C, or 78.5 to 95° F. Below 22° 
 C. or 71° F. few ova develop.) 
 
 The hot season in countries with temperate climates may 
 assist in the development of hookworm larvae in permanent 
 or temjoorary water or in damp earth, but, owing to the 
 length of time the larvfe require in order to reach the in- 
 
DISTRIBUTION. 43 
 
 fecting age, such regions are rarely intense seats of the 
 disease. 
 
 The relation of moisture to hookworm infection has been 
 noticed by all who have studied the disease. In the tropics, 
 in brickyards, and in tunnels and mines (coal, tin, salphur, 
 gold, diamond, etc) a certain degree of wetness of the soil 
 has been found to obtain wherever the hookworm disease 
 occurs. This agrees with facts regarding the life history 
 of the parasites, which will be discussed in another place. 
 Turner explains the absence of ankylostomiasis in certain 
 South African mines by the acidity, from sulphuric acid, 
 of the water. Deep, warm, wet, and alkaline mines are 
 especially affected. 
 
 Stiles has shown that in the southern states sandy soil is 
 more favorable than clay for the production of the disease. 
 This is probably due to the fact that in wet sand the larvae 
 can easily avoid drying and at the same time obtain oxygen. 
 On dry soil the larvae soon die, and among dwellers of such 
 places, as the Arabs of the Sahara desert and the Soudanese, 
 the disease is rarely seen. Deaderick has pointed out that 
 alluvium offers favorable conditions for the larvae, and that 
 all the ground conditions are not yet known. The Porto 
 Rico Commission has also shown that not only alluvium, but 
 also clay soils, offer numerous foci, but Leichtenstern could 
 find no larvae in the clay of brickyards. It is important to 
 distinguish between pools of water that may long remain 
 on clay and earth free from water. The life history of the 
 larvae (see Chapter III) will throw much light on the 
 subject. 
 
 Shade is an important element, and will have to be con- 
 sidered in connection with the life history of the larvae and 
 the modes of infection. Elevation is of no importance if 
 the other conditions are favorable; mountains, as the St. 
 Gothard tunnel, over 3,000 feet above sea level, as well as 
 coast lands, are involved. 
 
44 hookwoe:m disease. 
 
 Occupation and social position of hookworm subjects. — 
 
 Hookworms affect especially those who have intimate re- 
 lations to the soil. In the tropics it is especially the poorer 
 classes, the agriculturists and their families, that are af- 
 fected. According to the Porto Eico Commission, for ex- 
 ample, 85 percent of the nearly one million inhabitants are 
 poor and 75 percent are agriculturists. "The poorer the 
 man, the more exposed is he to heavy infection. Coffee 
 pickers and laborers on coffee estates are the most exposed 
 of all laborers on the island. Infection on sugar planta- 
 tions is not so common, but is nevertheless frequent, espe- 
 cially in the irrigating ditches. ' ' Washing at the edges of 
 streams and banana culture are other occupations leading 
 to infection. One of us has observed many instances in 
 charcoal burners and turpentine "dippers." The people 
 come from infected regions, and their occupations offer fa- 
 vorable conditions for the spread of the disease. 
 
 Gardening is a possible means of infection in the well- 
 to-do, as also in j)rofessional gardeners. 
 
 In many regions outside the tropics, hookworm disease is 
 rather a trade disease than an endemic. Mining and brick- 
 making have frequentl}^ been alluded to. The details of the 
 mode of infection are discussed in Chapter IV, but it may 
 be said here that in many places the wives and families of 
 miners and brickmakers, and sometimes gardeners, do not 
 share the disease. 
 
 Barefooted children. — In certain occupations infection 
 takes place through the hand, the bare feet, or through de- 
 fective boots. An imjoortant cause in the southern United 
 States is the habit among children, even of the better 
 classes, in the country of going barefoot. Not only country 
 children, but city children, in the summer vacations have 
 ground itch, and later hookworm disease, as we have ascer- 
 tained in dozens of instances. Even adults oecasionallv get 
 
DISTRIBUTION. 45 
 
 infected by wading- in pools, yielding to what Claude A. 
 Smith aptly calls "the joy of going barefoot." In heavily 
 infected regions persons of all kinds of classes and occupa- 
 tions, and of all ages, occasionally get the disease. In 
 some of these the method of infection is obscure. Dirty 
 vegetables or fruit, or skin infection by larvae-containing 
 water, are the most probable. 
 
CHAPTER HI. 
 
 -, ZOOLOGIC FEATURES. 
 
 Hookworms belong to the class of nematodes, the family 
 strongylidae and subfamily strongylinaB. 
 
 The nematodes form a very large class of worms, usually 
 long and narrow, from 1 millimeter to 40 to 100 centimeters 
 in length, round on section, and sometimes hair-like in their 
 proportions. The sexes are usually distinct; the males 
 usually smaller than the females, and generally distin- 
 guished also by the shape of the tail end, which is some- 
 times rolled in a circular, spiral, or cork-screw manner; 
 sometimes, as in hookworms, s]3read out like an umbrella, 
 or funnel-shape. The length of the body is sometimes 
 marked, as in ascaris, by four longitudinal bands. There 
 are in some species circular striations, and in others the 
 bodies are smooth, or furnished with papillae or other ap- 
 pendages. The mouth end varies in shape in different 
 genera, is generally narrower than the body beyond it, and 
 possesses six papillae. It passes into a muscular esophagus, 
 that also varies in shape and proportion in different genera, 
 and this in turn is followed by the chyle-gut and the 
 rectum, which opens near the tail end of the worm. The 
 nerves of nematodes are made up of scanty groups of gan- 
 glion cells and fibers, especially well developed around the 
 esophagus. The parasitic species have no special sense 
 organs. Some free-living ones have two reddish eyes, fur- 
 nished in some species with lenses. The excretory organs 
 consist of a system of tubes, ending in an excretory pore. 
 The genital organs are tubular. That of the male opens in 
 common with the rectum, and that of the female is separate 
 
 4G 
 
ZOOLOGIC FEATURES. 47 
 
 from and usually anterior to the anus. All male nematodes 
 have preanal and postanal papillae, which are used in 
 specific differentiation. The eggs are so-called ''simple 
 ova," containing only one kind of cell, and, though varying 
 considerably, are usually characteristic for each species. 
 Some species are oviparous, and others viviparous. The 
 development of nematodes is simpler than that of tape- 
 worms or flukes. In many cases, as ascaris, trichocephalus, 
 and oxyuris, there is no intermediate host; in others, as 
 dracunculus and filaria, there is. In some, as strongyloides, 
 there is reproduction outside the definitive host. In the 
 case of hookworms, as we shall see, part of the development 
 of the larvae takes place outside the host. Very few nema- 
 todes (strongyloides) reproduce outside the definitive host. 
 
 Round worms live partly in fresh or salt water, in earth 
 or mud, in decomposing matter of all kinds, partly parasitic 
 in various organs of animals, and very often in plants. 
 Familiar examples are the common intestinal round worm, 
 ascaris lumbricoides, the "vinegar eel" (anguillula aceti), 
 and the trichina spiralis (trichinella) ; one of the most in- 
 teresting is the "hair-worm" (gordius), popularly sup- 
 posed to develop from horse-hair put in water for that pur- 
 pose, and in rare cases found as a parasite in man. 
 
 The nematodes are subdivided into eight families: 
 
 1. Enoplidse. Live free; many species in sea water. 
 
 2. Anguillulidae. Characterized especially by a double 
 swelling of the esophagus ("rhabditic") ; live free, es- 
 pecially in fresh water or in earth, or in decomposing 
 material ("vinegar eels"); many are parasites of plants, 
 and a few of animals. Many are very minute. 
 
 3. Angiostomidae. Developing by heterogeny, contain- 
 ing the genus strongyloides. 
 
 4. Gnathostomidae. A small family, often parasitic in 
 wild animals, but very rarely in men. 
 
48 HOOKWORM DISEASE. 
 
 5. Filaridse. Very long, narrow worms, represented by 
 several species of important parasites, including filarise. 
 
 6. Trichotracliilid«. Containing several important para- 
 sites, especially trichina (trichinella) and tricliocephalus, or 
 the whipworm, a common parasite of man in warm coun- 
 tries. 
 
 7. Strongylidse. A very large group subdivided into 
 several sabfamilies. Besides hookworms, eustrongylus, 
 strongylus, and sclero stoma belong to this family. 
 
 8. Ascaridae. Containing the common parasitic round 
 worms and pinworms, and some others. 
 
 The strongylidsB form a very large family. They are 
 characterized by long, cylindrical bodies, rarely filiform; 
 the possession of six oral papillae — two lateral and four 
 sub median — generally projecting in the form of nodules or 
 conical points; a mouth capsule with or without teeth, 
 either in the body axis or turned dorsally or ventrally. The 
 esophagus is more or less swollen in the posterior part. The 
 males have a "bursa copulatrix" and one or two spicules; 
 the females have one or two ovaries. The eggs are usually 
 deposited in segmentation, sometimes containing the em- 
 bryo. The sexes are distinct. Important members are the 
 "colic worms" of horses and the kidney worms of hogs (but 
 not the kidney worms of dogs and man — Stiles), the "gape 
 worms" of chickens, and the hookworms. Many others are 
 frecjuent parasites of various lower animals, and occasion- 
 ally of man. The members of the family have undergone 
 many changes of nomenclature, not necessary to describe 
 fully in this place. There is also much difference of opinion 
 regarding the nomenclature and classification of the hook- 
 worms. The following list shows some of the most im- 
 portant synonyms in chronological order: 
 
 1789: uncinaria — Frolich. 
 
 1843: agchylostoma dnodoualo — llulnni. 
 
ZOOLOGIC FEATURES. 49 
 
 1845: ancylostoma duodenal e — Creplin. 
 1850: an cliylo stoma duodenale — Dubini. 
 1851 : ancylostomum duodenale — Diesing. 
 1851: strongylus quadridentatus — von Siebold. 
 1851: sclerostoma duodenale — Cobbold. 
 1861: dochmius anchylostomum — Molin. 
 1861: monodontus — Molin. 
 1866: strongylus duodenalis — Schneider. 
 1876: dochmius duodenalis — Leuckart. 
 1879: anchilostoma duodenale — Bozzolo. 
 
 Ankylostoma Duodenale. 
 
 The generic name above, or ankylostomum duodenale, or 
 ancylostomum duodenale (French, anchylostome; German, 
 ankylostomum or anchylostomum; Italian, anchilostoma) is 
 preferred in England and the continent for the old world 
 hookworm. No matter how spelled, Dubini 's name seems 
 justified by the accuracy of his description. The spelling 
 ' ' agchylostoma, " passable in Italian, would have to be 
 latinized for international nomenclature, "ancylostoma" 
 being the correct spelling. 
 
 The name uncinaria was widely adopted in America by 
 reason of the important work of Stiles, though Looss from 
 the beginning objected to the change on account of the fact 
 that the genus uncinaria of Frolich agrees with the type 
 criniformis (Goze) more than with ankylostoma duodenale 
 (Dubini). More recently (1907), Stiles states that "the 
 old genus uncinaria (type vulpis^ criniformis) must be 
 divided into at least four smaller groups: uncinaria (type 
 vulpis), agchylostoma (type duodenale), necator (type 
 Americanus), bunostomum (type trigonocephalum), and 
 probably into several additional units. . . . Evidence 
 is accumulating to the effect that they should be given 
 
50 HOOKWOEM DISEASE. 
 
 generic rank." The recent (1909) classification of Railliet 
 and Henry shows the same tendency. Besides the two 
 human species of ankylostoma and necator, there are sev- 
 eral species of the genus uncinaria which are found in 
 lower animals — e. g. : 
 
 Uncinaria canina, 
 
 Uncinaria stenocephala, tin dogs. 
 
 Uncinaria trigonocephala, 
 
 Uncinaria (ankylostoma) tubaeformis, or ^ 
 
 Uncinaria perniciosa, !>in cats. 
 
 Uncinaria Balsamoi, ' J 
 
 Uncinaria trogocephala, in shee^D. 
 
 Uncinaria radiata, in cattle. 
 
 Uncinaria Lucasi, in seals (thought by Looss to be the 
 cause of the great mortality — 17 percent — of suckling seals 
 on the Pribiloff Islands). 
 
 Uncinaria os papillatum, in elephants. 
 
 There is no j^roof that any of these infect man, and among 
 lower animals each genus infested seems to have its own 
 species of hookworms. The worm supposed by Rathonyi to 
 be a hookworm in mine horses in Hungar}^ has been shown 
 to be a sclerostoma. 
 
 In order to make clear the anatomic features of human 
 hookworm, it seems best to describe at length the one long- 
 est known, and to mention more briefly the points of differ- 
 ence in the new world 23arasite. In this we follow the 
 more exhaustive descriptions, especially of Looss, Stiles, 
 and Allen J. Smith. 
 
 The old world hookworms are small and almost cylin- 
 drical, the male about 10 millimeters long and 0.45 milli- 
 meters wide, the female 12 to 18 millimeters long and O.GO 
 millimeters wide. (Frontispiece.) In both sexes the an- 
 terior end tapers gradually. In the female the jDosterior end 
 tapers to a fine point or spine. (Fig. 1.) The posterior end 
 
ZOOLOGIC FEATUKES. 
 
 51 
 
 J— > 
 
 
 p< 
 
 be 
 
 
52 HOOKWORM DISEASE. 
 
 of the male tapers in about the last quarter of its length, but 
 the tip of the tail is concealed by the bursa, which flares out 
 to a width equal to that of the thickest part of the body, or 
 even more, giving the tail end a square or sometimes con- 
 cave appea^'ance at the end. The color when alive is some- 
 what flesh-red or cream color; when dead, duller, gray or 
 grayish white. The posterior two-thirds are often brown 
 or reddish brown, from blood in the intestine. The skin is 
 smooth, delicate, with fine transverse striations, AVith the 
 bending of the worm transverse folds are formed, especially 
 about the head. The name hookworm is often supposed to 
 be due to the bending of the head backwards, and this is so 
 striking a feature that the supposition is natural, though 
 the name was given on account of other "hooks," as has 
 l)een mentioned before. Eight (Smith) — Looss, four — mus- 
 cular bands, most pi ainl}". defined on the sides, symmetric- 
 ally arranged, run the length of the body, merging to- 
 gether laterally to form a fairly continuous body wall, and 
 in the male help to form the bursal ribs. 
 
 Besides the proper skin muscles, Looss describes certain 
 special muscles, such as the anal muscles, in female worms 
 only; the vulvar muscles; the cephalo-esophageal muscles, 
 which pass from the top of the nervous ring to the surface 
 of the esophagus, and, extending obliquely forward through 
 the bod}^ cavity, are inserted partly in the skin and partly 
 in the mouth capsule. They probably assist in the move- 
 ments of the head, as well as in those of the buccal capsule. 
 The end of the chyle -gut is surrounded by a network of 
 muscles, especially well developed in males. In both sexes 
 there is a sphincter muscle of the rectum. Finally, there is 
 a complicated system of muscles in connection with the 
 tail end of the male. 
 
 The body cavity is divided by a membranous septum at- 
 tached dorso-ventrally, in the folds of which, as in a mesen- 
 
ZOOLOGIC FEATITKES, 
 
 Do 
 
 -Ceri^g/.s. 
 
 Fig-. 2. Male hookworm (ankyl- 
 ostoma duodenale) of man. ac. "p., 
 accessory piece to spicules; a. p., anal 
 papilla; h. c, buccal capsule; can. cerv. 
 gl. s., canal of left cervical gland; cerv. 
 gl. d., right cervical gland; cerv. gl. s., 
 left cervical gland; cu., cuticle; cul., 
 cul de sac of testicular tube; e., 
 esophagus; e'., posterior end of 
 esophagus; e. p., ventromedian excre- 
 tory pore; ej. can., ejaculatory canal; 
 int., intestine; I. r., lateral ray of bur- 
 sa; m., muscular layer; p., lateral 
 precaudal papilla; sp., spicules; sp'., 
 anterior end of spicules; test., testicu- 
 lar tube; ves. sem., vesicula seminalis; 
 V. v., ventral rays of bursa. Greatly 
 enlarged. (After Schulthess, copied 
 from Blanchard. ) 
 
54 
 
 HOOKWORM DISEASE. 
 
 tery, tlie alimentary canal is supported. In tlie two divi- 
 sions of the cavity are the cervical and esophageal glands, 
 the sexual tubes and glands, and the anal glands. (Fig. 2.) 
 The alimentary apparatus consists of the mouth and its 
 appendages, the esophagus, and the straight intestinal 
 canal, which extends to the posterior end in each sex, termi- 
 nating independently in the female, but in the male form- 
 ing a cloaca with the sexual apparatus. 
 
 Fig. 3. Dorsal view of anterior end of the old world hookworm (ankylos- 
 toma duodenale; of man. Greatly enlarged. (After Perroncito.) 
 
 The mouth 23arts of a hookworm are remarkable and com- 
 plicated, and furnish important features for the specific 
 diagnosis of the worms. The mouth in the old world worm 
 Oldens toward the back of the parasite, on account of the 
 dorsal bend, so tliat the rini of the mouth is nearly or cpiite 
 parallel to the long axis of the l)ody of the worm. (Fig. 1.) 
 Tlie mouth capsule, or "buccal capsule," is of half-oval or 
 cup shape, the anterior axis curved and long, the posterior 
 shorter and nearly straight. The bottom of the mouth cav- 
 ity is flat, uneven, and nearly transverse to the long axis of 
 
ZOOLOGIC FEATURES. 55 
 
 the animal. (Fig. 3.) Seen from the front, the mouth 
 is somewhat longer dorso-ventrall}^ than laterally. The 
 framework of the mouth is made up of a number of 
 chitinous plates, or, according to Looss, a continuous plate 
 with suture-like depressions, giving it rigidity, but per- 
 mitting changes of shape, such as are demanded by the 
 function of the mouth, and especially holding on to or let- 
 ting go the mucosa of the host. The shape of the opening 
 varies much with the degree of dilatation of the orifice at 
 the time of examination or fixation. On the ventral side of 
 the capsule, just within the cavity, are two pairs of sharp- 
 pointed, curved, hook-shaped teeth; at the base of the cap- 
 sule, on the ventral side, two triangular pointed teeth, or 
 ''lancets," and on the front of the dorsal part two tooth-like 
 structures separated by a fissure. "Beneath the buccal 
 rim the lining of the cavity is thrown into six papillary 
 prominences, characteristic of the entire group." (Smith.) 
 In the middle of the dorsal wall of the mouth capsule is the 
 orifice of the duct of the dorsal esophageal gland. From 
 the hook-shaped ventral teeth the so-called cervical glands 
 extend almost to the middle of the body. (Fig. 8.) 
 
 The esophagus begins at the base of the buccal capsule, 
 and extends as a thick-walled, long flask-shaped organ, 700 
 to 800 microns long and 150 to 175 microns wide at the 
 widest (posterior) part. Its lumen on transverse section is 
 triangular or triradiate. At the lower end, above the nar- 
 rower intestine, is a trilobed valve. Looss says the muscles 
 along the three angles of the esophagus can be distinguished 
 optically and chemically from the ordinary muscles along 
 the lumen. Between the esophagus and the body wall are 
 the well-developed nervous system and the esophageal 
 glands. The former appears to communicate directly with 
 the nervous ring, and consists of three longitudinal nerves 
 which run the whole length of the esophagus in the middle 
 line of the three sectors. At three places are annular com- 
 
56 HOOKWORM DISEASE. 
 
 misural fibers, from which finer fibers pass in difi^erent 
 directions. 
 
 Lying in the three grooves along the esophagus are three 
 small glands, called the esophageal glands (Figs. 8, 9), 
 which become continuous toward the posterior part of the 
 esophagus. Their ducts pass forward and empty into the 
 buccal capsule. According to Looss, the ducts of the 
 lateral glands open close to the rim of the mouth, outside 
 the lateral hook-shai^ed teeth, and that of the posterior 
 gland in the dorsal wall of the capsule. Smith is not able 
 to differentiate the cephalic or head glands of Looss from 
 the anterior ends of the esophageal glands. 
 
 Near the level of the jDosterior end of the esophageal 
 glands, about midway in the length of the esophagus, or 
 500 to 600 microns from the front of the head, on each side, 
 is a small conical papilla. Through this opens the duct 
 (sometimes called the "excretory canal") of the cervical 
 gland, a large glandular structure lying along the caudal 
 end of the esophagus and the cephalic end of the intestine. 
 (Figs. 8, 9.) The chyle-gut is made up of two rows of cells, 
 surrounded by a muscular wall. 
 
 On each side of the anus in each sex are several small 
 bodies formerly called ganglion cells or "anal glands," 
 which open into the intestinal canal. Their function is un- 
 known. 
 
 The sexual opening of the female in ankylostoma duo- 
 denale is at the posterior third of the body. Mink (1909) 
 reported an anomaly in an old world worm — the vagina 
 opening at the junction of the anterior and middle thirds. 
 The short vaginal tube passes in and divides into an an- 
 terior and posterior uterus, each one continuous with the 
 narrow ovary which lies in transverse folds along the in- 
 testine. According to Looss the length of each genital tube 
 is five to six times the length of the body of the worm, the 
 
ZOOLOGIC FEATURES. 57 
 
 total length tlierefoi'e being ten to twelve times as long. 
 The beginning of the nterns in all mature females contains 
 masses of spermatozoa, and is sometimes called the "recep- 
 tacnlum seminis." The ovary of the posterior uterus coils 
 upon itself and passes forward, to terminate with the an- 
 terior ovary in the anterior half of the body of the worm. 
 At the end of the vagina is the complicated "ovijector," 
 surrounded by a dense layer of muscle cells. Looss gives 
 the two parts of this organ the names ''pars haustrix" and 
 ''pars ejectrix." 
 
 Within the uteri the characteristic ova are seen in great 
 numbers, and in varying degrees of segmentation. Smith 
 speaks of some with embrj^os in the uterus, but does not say 
 whether these were in recently passed worms. We have 
 never seen this, and think it probable the embryos had de- 
 veloped after the worms left the body of the host in old 
 specimens. 
 
 The male sexual glands have an appearance analogous 
 to that of the female, and consist of a long plicated tube 
 along the intestine on each side of the worm, reaching as 
 far as the cervical glands, opening into a sac, the seminal 
 vesicle, about the middle of the body. From this a tube, 
 the ejaculatory duct, passes to the cloaca, which opens in a 
 papilla on the ventral side of the tip of the tail, within the 
 bursa. (Fig. 2.) The duct is covered b}^ the "cement 
 gland," the secretion of which serves to fasten the male to 
 the female during copulation. The opening of this is 
 guarded by a chitinous forked process, the point directed 
 toward the tail, and the intercornual space occupied by a 
 delicate valve-like layer. From the opening two long 
 slender "spicules" (Fig. 2) extend. They vary in length, 
 but are almost two millimeters long generally. Each one 
 has at its base an "exsertor" muscle and two retractor 
 muscles. 
 
58 
 
 HOOKWORM DISEASE. 
 
 The bursa is an umbrella-like expansion of cuticular 
 folds, supported by extensions of the muscular body wall, 
 spoken of as rays. The dorsal lobe is not divided, and the 
 dorsal rays are united to about two-thirds of their length 
 
 Tail 
 
 Dorsal ray 
 
 Dorsolateral ray 
 Lateral ray 
 
 ..., Sutaventral 
 ray 
 
 Ventrolateral 
 ray 
 
 Ventral ray 
 
 Fig-. 4. A, caudal bursa and,, tail of male uncinaria duodenalis. B, caudal 
 bursa and tail of male uncinaria Americana. Drawn to scale to show differ- 
 ence in size. (After Allen J. Smith.) 
 
 from the base. Each division is tripartite. There is no 
 ventral lobe. The bursa and its muscular rays enable the 
 male in sexual contact to grasp firmly the body of the 
 female and properly coapt the sexual parts. (Fig. 4.) 
 
 S^ 
 
 Fig'. 5. Ankj'lostoma duodenale 
 in copulation. Drawn by Dr. J. H. 
 Gage from specimen presented by 
 Dr. Walter Brem. 
 
 Fig. 6. 
 from dog. 
 
 Copulating- hoolvworms 
 
 The eggs are oval, with broadly rounded poles; the shell 
 is colorless, measuring 0.056 to 0.061 millimeters in length 
 and 0.034 to 0.038 millimeters in width. (Fig. 11.) In 
 fresh stools the eggs are usually in four segments, rarely in 
 fewer or more, and with a broad space between the seg- 
 ments and the shells. (See Chapter VII.) 
 
ZOOLOGIC FEATURES. 
 
 59 
 
 Necator Americanus. 
 
 Synonyms. — Uncinaria Americana — Stiles, 1902; ankyl- 
 ostoiiinm Americanum — von Linstow, 1903; uncinaria 
 (necator) Americana — Stiles, 1903; micinaria liominis — 
 AsMord, King, and Gutierrez, 1904. 
 
 Fig-. 7. Necator Americanus. Upper lialf males, lower half females. 
 Inch measure. 
 
 The name (necator = murderer) given by Stiles to the 
 species first shown by him to have generic characters. 
 Stiles first named it uncinaria (1902), having clearly de- 
 scribed the differences between uncinaria cluodenalis, but 
 believing the worm to belong to the same genus. It is in- 
 teresting to note that Lutz, in 1888, stated that the Brazil- 
 ian hookworm did not have hook-shaped teeth. Leuckart's 
 description of dochmius duodenalis (1876) was based on 
 
GO 
 
 HOOKWOK^I DISEASE. 
 
 new world specimens. Looss suggests tlie latter were sent 
 by Wuclierer or Lutz from Brazil, but the original material 
 could not be found. Allen J. Smith also recognized the 
 difference between this and the old world species. Both 
 terms of the name have been criticised — ''necator" because 
 the parasite is not more murderous than its old world con- 
 gener, and ''Americanus" because it has a world- wide ex- 
 tent. The objections are invalid from the standpoint of 
 zoologic nomenclature. 
 
 Buccal cavity Ventral buccal lip 
 
 Border of membranous mouthi, 
 
 \- Buccal papillcB 
 
 Dorsal conical tooth 
 
 Head g-land (?) 
 
 Esophageal gland 
 
 Dorsal buccal lip 
 
 Esophagus 
 
 Duct of cervical gland opening 
 on cervical papilla 
 
 Fig. 8. Dorsal aspect of head end of uncinaria Americana. 
 J. Smith.) 
 
 (After Allen 
 
 This worm is almost as long as, but more slender than, 
 ankylostoma. The males measure 6 to 10 millimeters and 
 the females 8 to 15 millimeters. (Fig. 7.) The mouth 
 capsule is small and glol)ular and its orifice rather quad- 
 rate. (Fig. 10.) There are no teeth on the free edge, but 
 
ZOOLOGIC FEATURES. 
 
 61 
 
 two broad lips — dorsal and ventral — extend inward to or 
 beyond the edge of the membranous lip. The base of the 
 larger of the lips reaches from the ventromedian line to 
 
 Ventral lancets Chitinous buccal capsule 
 
 Head glands (?) 
 
 Esophageal gland 
 
 Cervical papil 
 
 Cervical gland 
 
 Papillae 
 
 uccal cavity 
 Dorsal conical tooth 
 Liateral lancets 
 
 [•Esophageal gland 
 
 Esophagus 
 
 Intestine 
 
 Fig. 9. Lateral aspect of head end of uncinaria Americana. (After Allen 
 J. Smith.) 
 
 about the middle of the lateral aspect of the rim; the 
 smaller one from the dorsomedian line about two-thirds of 
 the distance to the ventral lip. They cover two cutting- 
 plates. (Figs. 8, 9.) There are two pairs of ventral 
 
62 
 
 HOOKWORM DISEASE. 
 
 teetli — tlie lower pair small and conical, and a blunt, coni- 
 cal, dorsal tooth (Fig. 8), projecting into the capsule. 
 Through it passes the duct of the dorsal esophageal gland. 
 Near its base, on each side, is a chitinous plate. 
 
 Buccal hook 
 Buccal teet 
 
 Anterior buccal lip 
 
 Posterior buccal lip 
 iDorsal conical tooth 
 
 A B 
 
 Fig. 10. A, dorsal view of liead end of uncinaria duodenalis. B, dorsal 
 view of head end of uncinaria Americana. Drawn to scale to show difference 
 in size. (After Allen J. Smith.) 
 
 The sides of the bursa are very long, so that the bursa 
 seems as if two-lobed. (Fig. 4.) The female genital open- 
 ing is in front of the middle of the body. The eggs re- 
 semble those of the old world hookworm closely, but are 
 
 Fig-. 11. Embryology of the old world hookworm (ankylostoma duode- 
 nale) of man; a, h, c, d, e, f, g, segmentation of the eg-g-; h, i, j, the embryo; fc, 
 a rhabditiform embryo escaping from its eggshell; /, m, empty eggshells. 
 Greatly enlarged. (After Perroncito.) 
 
ZOOLOGIC FEATURES. 63 
 
 sligiitly larger (0.054 to 0.072 millimeters long and 0.036 
 millimeters tliick), and tapering toward the poles. (Fig. 
 13.) 
 
 The vital characteristics of necator Americanus have not 
 been so closel}^ investigated as those of ankylostoma, but 
 are the same so far as examined. Experiments by Claude 
 A. Smith and Fieri (though the latter rejected the con- 
 clusions) prove the skin infection to take place in the same 
 way. 
 
 Ankylostoma and necator have been found only in human 
 beings. Von Linstow (1903) reported the occurrence of 
 necator in a chimpanzee (simia troglodytes) in West Africa, 
 but Looss doubts the diagnosis. 
 
 Development of Ankylostoma Duodenale. 
 
 The females lay their eggs in the intestine of the host, 
 and the ova are expelled with the feces, and under proper 
 conditions develop. The rapidity of development depends 
 upon the temperature, moisture, and available oxygen, as 
 also perhaps on absence of light. Development is most 
 rapid at 25°— 35° C. (77°— 95° F.). A few develop at 
 22° C. (71° F.), and Tenholt found that some developed in 
 mines at 20° C. (68° F.) from eggs to larvse in fourteen days. 
 Freezing often kills ova, and low temperature prevents seg- 
 mentation, but the possibilities of the development of these 
 worms appear very strikingly from some experiments of 
 Oliver (1910). He froze feces until hard, but after gentle 
 thawing larvae appeared on the sixth day. Kept in a cold 
 cellar at 15°— 17° C. (59°— 62.3° F.) for ten weeks, there was 
 no segmentation, but when raised to a moderate tempera- 
 ture segmentation went on and gave rise to stronger and 
 more vigorous larvji? than those hatched immediately. Ex- 
 posure to light snow does not kill eggs or larvae. Tempera- 
 
64 
 
 HOOKWOEM DISEASE. 
 
 tures of 50° C. (122° F.) kill larvae, probably from drying. 
 Complete desiccation is one of the most certain causes of 
 death. Deprivation of oxygen also checks development, 
 
 Fig. 12. Two larvfp of the old world hookworm at the end of the second 
 stage ("encysted larv.-E"). representing the young worms retracted from their 
 skin. (After Perroncito. > 
 
 and, if continued sixteen days, the eggs die. It is the pres- 
 ence of oxygen that makes eggs on the surface of stools 
 develop more rapidly than those in the depths, which either 
 
ZOOLOGIC FEATURES. 65 
 
 die or develop only when the mass becomes loose. (See 
 Chapter V.) Direct sunlight lulls the ova, diffuse day- 
 light checks development, and darkness favors it. 
 
 The eggs resist adverse conditions very much at times. 
 Lambinet and Boycott and Haldane found they could be 
 kept from air nine to ten days and then develop. 
 
 Fig. 13. Ova of (A) uncinaria duodenalis and (B) uncinaria Americana. 
 Drawn to scale to show comparative size. (After Allen J. Smith.) 
 
 Eggs also die usually in water or in watery stools, but, on 
 the other hand, larvae can often be cultivated under such 
 conditions. Larva can be raised sometimes either in the 
 natural stool or one made into a thick paste with water, 
 but, as Looss pointed out, acid fermentation of stools may 
 kill all the larvae, even before they escape from the egg- 
 shells. Boycott and Haldane, however, found that larvae 
 grew for them in acid stools. Looss also points out that 
 the constituents of the feces are important in this con- 
 nection. In his own infection (experimentally produced) 
 he found that pure vegetable diet produced a less favorable 
 medium for the ova than mixed diet, especially if stools 
 from the latter were mixed with equal part of moderately 
 finely pulverized animal charcoal (made from bones, not 
 blood) and made into a thick, tenacious mass with water. 
 Diarrheal stools mixed with animal charcoal also permit all 
 the ova to develop. 
 
 While complete desiccation kills both eggs and larvae, en- 
 cysted larvae resist drying for a long time. There is 
 much divergence in regard to the effect of drying on ankyl- 
 ostoma larv<T, but the differences of opinion probably de- 
 
66 HOOKWORM DISEASE. 
 
 pend upon errors in teclinic — sometimes perhaps on mis- 
 takes in the diagnosis of the larvae. 
 
 The larvae, after escaping from the eggs, feed on the feces 
 and grow. They measure 0.2 to 0.25 millimeters long and 
 0.01 to 0.017 millimeters thick. They are at first rhabditi- 
 form — thaf is, the esophagus shows three parts. It be- 
 comes narrow beyond the middle, and then swells out again 
 in an onion shape. In the interior of the swelling are three 
 small valves, that can sometimes be seen to open and shut. 
 (Fig. 11, k.) Characteristic of the hookworm larva is a 
 long, cylindrical mouth cavity, with a globular dilatation at 
 the posterior part, lined by a highly refracting membrane. 
 The tail end is sharply pointed; in front of it is the anus, 
 and still farther in front the anlage of the sexual organs, 
 showing as a small oval body. 
 
 Four moults are passed through during development of 
 the larvae, making five stages after incubation, including 
 full development. The first shedding of the skin, or 
 ecdysis, takes place usually within two to five days after 
 incubation, depending upon the temperature and other con- 
 ditions. In this there is no change of shape. The new skin 
 is formed under the old one. After this moult, again with a 
 lapse of time depending on the temperature, the larvae grow 
 and change their shape. The body becomes longer (0.7 to 
 0.8 millimeters) and thinner, and the characteristic shape of 
 the mouth and esophagus are lost. The second ecdysis is 
 prepared for, and reached in five to nine days usually, but 
 the old skin is not shed as soon as the new one is ready. On 
 the contrary, the old skin surrounds the body as a delicate 
 sheath, in which the larva has room to move forward and 
 back. This is the (falsely) so-called "encysted" stage. 
 (Fig. 12.) The larvae are now called "ripe." Growth 
 and feeding cease, and the free stage of the larvae is ended. 
 They now endeavor to leave the feces and to get into moist 
 
ZOOLOGIC FEATURES. 67 
 
 earth, moist wood, or water. As Looss discovered and re- 
 ported in 1897, tliey bore through filter paper on which 
 feces are incubating, and in that way can be easily obtained 
 free from fecal contamination. They also pass through a 
 sand filter, even if the water is not running. In various 
 media they may live a long time, and show remarkable te- 
 nacity of life. Belger and Oliver found them alive in water 
 sealed in vaseline four months. One of them wriggled into 
 the vaseline and lived nearly to the end of the fifth month. 
 Looss kept them alive in water three hundred days, and 
 Oliver more than eleven months. Perner found them alive 
 in mine sludge ten months after the mine had been closed. 
 In distilled water they live only two to nine days. During 
 this time they live upon certain granular particles in the 
 glands of the intestine, the latter becoming in time almost 
 transparent, instead of granular and opaque as before. In 
 water they are not able to move freely, but sink if the water 
 is still. On the other hand, if the temperature is not too low, 
 they have a strong tendency to migrate, and especially to 
 crawl up on all sorts of objects kept moist by water. Looss 
 found that if he put a piece of wood in the culture glass, 
 with one end out of the water, all the larvae in a short time 
 would crawl up to the top of the stick, which was kept moist 
 by the water below. Tenholt reports an observation in 
 which larvae that developed from ova in feces at the lower 
 end of a wet mine timber reached a height of one meter 
 above the ground in twenty days, or not more than sixteen 
 days after reaching the larval stage. The same observer 
 found larvae in the cracks between the boards of a bath- 
 house. Hermann and Galli-Valerio observed penetration 
 of elder pith by larvae over night. It is in this stage that 
 the larvae are infectious. Eggs or young larvae are not cap- 
 able of infection, even if swallowed. 
 
 Leichtenstern formerly believed that ankylostoma could 
 
68 HOOKWOEII DISEASE. 
 
 develop by lieterogeny — that is, the larvae developed out- 
 side the body into males and females, the offspring of which 
 in turn were infectious. Leichtenstern later abandoned the 
 view, but it was put forward also by Giles in Assam, and 
 later bys Ozzard, Annett, and Eoss. As has been pointed 
 out by Looss and other observers, and recently (1909) by 
 Leiper in criticism of Ozzard, the idea depends upon con- 
 fusion of ankylostoma larvae with those of other nematodes, 
 especially strongyloides stercorals, sometimes free living 
 nematodes, of which there are so many species, and failure 
 to sterilize the sand used for culture medium. 
 
 As an example of the necessity of extreme care in such 
 work, Leiper cites an observation in which a stool was kept 
 in a glass bottle in the laboratory for a year. The bottle 
 had formerly contained an alcohol preparation. Later the 
 bottle was found to contain forms resembling free adult 
 strongyloides intestinalis, but it became certain later that 
 they were the larvae of free living nematodes. Leiper also 
 points out that, while the ova of hookworms as found in 
 human feces are diagnostic, they can not be distinguished 
 from the larvae of all other nematodes. 
 
 As Looss has shown, the picture of Giles, purporting to 
 represent the development of the male rhabditis of ankyl- 
 ostoma, shows three different species, as indicated by the 
 shape of the tails. 
 
 The larvae, like the eggs, are easily killed by drying. 
 Galli-Valerio and also Fieri, however, found that they could 
 be dried, but revived up to twenty-four hours after. Differ- 
 ences in the results of various experimenters are to be ex- 
 plained by the difficulty of perfect desiccation within the 
 capsule. Galli-Valerio found that, while noncapsulated 
 larvae die at 40° C, encapsulated ones could resist a temper- 
 ature of almost 50° C. He also found encapsulated larvre 
 alive in a bottle of feces kept nearly a year. The feces 
 were still moist, and the larvae only on the surface. 
 
ZOOLOGIC FEATURES. 69 
 
 Chemical disinfectants. — The larvae are resistant to chem- 
 ical agents. Scliiift'ner kept them alive almost four months 
 in water witli two or three drops of 1-percent quinine solu- 
 tion to 10 cubic centimeters. Oliver found that sea- water 
 killed them in tliirty-seven minutes. 
 
 Stronger disinfectants kill both eggs and larvae, as is 
 mentioned more fully in Chapter IX. 
 
 An interesting light was thrown on the possible modes of 
 dissemination of the eggs and larvse of hookworms by Galli- 
 Valerio (3905). He placed eggs and larvse of ankylostoma 
 duodenal e in a bottle with flies, and on washing the flies 
 found many eggs and encapsulated larvse which had ad- 
 hered to their bodies, but none in the flies' intestines. 
 
 Having been taken into the body in any of the various 
 ways described in Chapter IV, the larvae undergo two other 
 moults before becoming mature. The details of these 
 stages are not known, but certain facts are established. 
 Both in the mouth infection and in some cases of skin infec- 
 tion, as in Looss' experiments on young dogs, the larvae 
 appear in the intestine in ten days. 
 
 In skin infection in guinea pigs, larvae reach the trachea 
 in fourteen days. They have not grown appreciably, but 
 are perfectly agile. They evidently do not all travel with 
 the same speed. Doubtless many are kept back for a time 
 or permanently by the lymph glands. Looss, however, 
 found eggs in the feces after skin infection in thirty to 
 thirty-five da^^s. Tenholt's assistant found a few eggs in 
 his stools forty-seven days after skin infection, and then 
 they rapidly became more numerous. In the accidental in- 
 fection in himself Looss did not find eggs until the seventy- 
 first day, the same period that elapsed in Fieri 's case, but 
 in young dogs Looss found a few adult worms at thirty to 
 thirty-five days. 
 
CHAPTER IV. 
 
 ^ MODES OF INFECTION. 
 
 Two modes of infection with hookworms are known and 
 have been proved experimentally — i. e., through the mouth 
 directly and through the mouth indirectly by way of the 
 skin. For reasons that will appear below, direct mouth 
 infection, though it may occasionally occur, is of minor im- 
 portance in the production of hookworm disease. Skin in 
 fection, we believe, is practically the only source of the 
 disease. Different species of hookworms have been found 
 parasitic in various lower animals — namely, dogs, sheep, 
 cattle, horses, pigs, cats, foxes, seals, badgers, etc. These 
 are distinct from those infecting man, and have not 
 been found in man. Two species infect man — ankylostoma 
 duodenale and uncinaria Americana — ^both of which have 
 been found experimentally to be capable of entering the 
 skin of lower animals, but they have not reached adult 
 life in the intestinal canal of any animal besides man, 
 except possibly the chimpanzee, the gibbon, and the gorilla. 
 They reach adult life or the reproductive stage only in the 
 intestinal canal of man, where they lay eggs, which pass 
 out with the feces. The eggs can not hatch in the intestinal 
 canal for lack of oxygen and possibly for other reasons, 
 such as the presence of acids, gases, etc., produced by the 
 intestinal bacterial flora. Moreover, it has been shown con- 
 clusively by Looss, working with the old world hookworm, 
 by Claude A. Smith, working with the American species, 
 and by others, that the young worms can not infect until 
 they have reached a certain stage (the encysted stage) of 
 their life, which requires at least four or five days after they 
 
 70 
 
MODES OF INFECTION. 71 
 
 are hatched out, which itself requires eighteen hours or 
 more after the feces have been expelled. The above stated 
 facts — that the reproductive stage of the parasite is reached 
 only in the intestinal canal, that the species infecting man 
 do not infect other animals, that the eggs do not hatch in 
 the intestinal canal, and that the larvse are not infectious 
 until they are at least four or five days old — show that the 
 feces of infected persons are the real sources of every hook- 
 worm infection, and, further, that a man can not directly 
 infect himself. 
 
 The number of eggs passed with each stool of a heavily 
 infected person is enormous. Leichtenstern estimated the 
 number passed daily in one of his cases of ankylostomiasis 
 to be over 4,000,000. Bass counted the eggs in one deci- 
 gram of feces from a severe case of uncinaria Americana in- 
 fection, originating in Louisiana, and calculated the num- 
 ber in the entire stool to be 4,490,000. We estimated that 
 the daily stool of a patient with apparently only a moder- 
 ate infection, and 70 percent of hemoglobin, contained 
 1,700,000 eggs. Remembering that the average number of 
 worms in the severe cases in this country ranges between 
 1,000 and 4,000, it is obvious that it would not require more 
 than one-thousandth part of the eggs in one such stool 
 to give rise to a severe infection if all developed. In the 
 light of these figures, the wonder is that the disease is not 
 far more destructive of human life than it is. 
 
 Requirements for Hatching. 
 
 Hookworm eggs do not hatch in the intestinal canal, as 
 has already been stated, nor do they hatch in undiluted 
 feces, except under certain special conditions. We have 
 often kept feces containing hookworm eggs in the labora- 
 tory for months at a time in liquid condition without any 
 
/2 hookworjm disease. 
 
 hatching- whatever. In fact, we have kept them in this 
 condition in tlie bacteriologic incubator at body tempera- 
 ture for a month and have never seen hatching occur in such 
 specimens. If, on the other hand, pure feces are exposed to 
 drying, maay of the eggs near the partially dried out sur- 
 face of the fecal mass will hatch out, but the eggs deeper in 
 remain undeveloped. Claude A. Smith noted that if feces 
 containing uncinaria eggs were exposed to flies that infect 
 them with their larvae, the constant mixing and aeration 
 (oxygenation) by the larvae crawling through the mass per- 
 mits rapid and complete hatching. We have had occasion 
 to confirm this observation in several instances. Though 
 hatching in undiluted feces may occur under the favorable 
 circumstances mentioned, the larvae die out before they are 
 twenty-four to forty-eight hours old and before they are in- 
 fectious, except that a few may sometimes live longer in the 
 partially dried out feces. Dilution of the feces with one or 
 more times their bulk of almost any inert porous substance 
 — like charcoal, sand, dirt, etc. — puts them in the most fav- 
 orable condition. The best results we have ever seen were 
 obtained with equal quantities of charcoal and feces. 
 Looss found animal charcoal the most satisfactory diluent. 
 We have seen nearly as good results from using sand. We 
 made the following experiments for the present work: 
 
 Feces containing many uncinaria eggs were mixed with 
 each of the following materials about in the proportion of 
 one part feces to two of diluting material: powdered char- 
 coal (pine), white sand, sand plus about 5 percent slacked 
 lime, sandy soil, black clay soil, and pipe clay, all sterilized 
 before mixing. All were thoroughly mixed and contained 
 about the same amount of moisture. An accident occurred 
 to the specimen which the limed sand entered into and it 
 was lost. The remaining five specimens were placed in 
 glass dishes without covers and put in a bacteriologic in- 
 
MODES OF INFECTION. 73 
 
 ciibator (at 37° C), in which several sponges saturated with 
 water were placed to keep up moisture and prevent undue 
 drying out of the specimens. After fifty-four hours in the 
 incubator the cultures were carefully examined and the 
 following results noted : 
 
 Feces plus charcoal: many larvai', a few empty shells, and 
 no eggs found. 
 
 Feces plus sand: many larvae, a few shells, and two seg- 
 menting eggs found. 
 
 Feces plus sandy soil: many larvae, a few segmenting 
 eggs, and three containing embryos were found. 
 
 Feces plus black clay soil: in slides made from near the 
 surface a very few larvae were found and many more eggs, 
 many of which contained dead embryos. Deep in the mix- 
 ture no progress toward hatching appeared to have been 
 made. 
 
 Feces plus pipe clay: no larvae could be found, but near 
 the surface of the mixture a few dead embryos could be seen 
 in the egg shells. 
 
 The charcoal, sand, and sandy soil specimens remained 
 porous and friable, but the clay soil and pipe clay speci- 
 mens ran together and were sticky. In spite of the pre- 
 caution to prevent it, all of them dried out considerably, and 
 the clay specimens were coated with a thin hard crust. The 
 experiment shows that best hatching follows dilution of 
 feces with material producing a porous mixture, whereas 
 the sticky nonporous mixture prevents hatching, chiefly, no 
 doubt, by depriving the eggs of oxygen. Where the soil is 
 sandy and porous, rains dilute and mix feces with the soil 
 and put the eggs in the most favorable condition in this 
 regard for hatching. There would be far less mixing of 
 feces with a sticky clay soil, and, if so mixed, hatching is 
 prevented. This may explain the much greater prevalence 
 of the disease is sandy regions. 
 
74 HOOKWOEM DISEASE. 
 
 Moisture is very necessary for hatching of hookworms, 
 but no great amount is required. It is more essential for 
 the maintenance of the life of the larvae. They live well in 
 water or moist earth, but drying soon kills them. Bentley 
 found th^t gentle drying for six hours kills them. Rains 
 are important in scattering the feces and mixing them with 
 the soil, and also in keeping up the essential moisture. 
 They are also important factors in producing skin infection 
 by liquefying and helping to apply the infectious cultures 
 to the skin, as we shall see later. 
 
 Shade is an important factor, both in the hatching of 
 hookworm eggs and keeping the larvse alive, by maintain- 
 ing the essential moisture and preventing fatal drjdng. 
 We exposed a culture of six-day old uncinaria larvse to the 
 direct April sunshine for two days, adding water as needed 
 to prevent drying, and they were still alive and active at 
 the end of the experiment. 
 
 If feces containing eggs are diluted with dirt, sand, 
 or other material, and favorable conditions of moisture, 
 warmth (temperature between 22° and 35° C. = 71.6° and 
 95° F.), and shade exist, the microscopic larvae begin to 
 hatch out and crawl about in the diluted feces iu twenty- 
 four hours. In two or three days they shed their skins. 
 This is the first ecdysis. After about five days from the 
 time they were hatched out the organism begins a second 
 stage of development or ecdysis, but this time it remains in- 
 side of the skin it has cast or retracted from, and is spoken 
 of as encysted. In this condition it is capable of infecting, 
 but was not before. Before the larva? become encysted they 
 are easily killed by sunlight, changes of temperature, too 
 much dilution of the feces with water (1 to 1,000 or above), 
 drying, and often the chemical constituents of feces. It 
 results, therefore, that actually very few larvse that hatch 
 out reach the encysted or infectious stage. Only in rainy 
 
MODES OF IXFECTIOX. 75 
 
 seasons, or wet spells lasting six or more days, would suf- 
 ficient moisture be continually supplied, except in some 
 specially favorable spots, to bring them to this stage. Too 
 much rain often results in sufficient dilution to kill them. 
 Only in favorable places or favorable seasons do they es- 
 cape the destructive sun's rays and drying. Only in warm 
 seasons do they hatch out. From these facts result the 
 very much greater jDrevalence and intensit}^ of the infection 
 in tropical countries. 
 
 In the encysted condition the microscopic larvas may live 
 many months under favorable conditions of moisture, shade, 
 and temperature. They resist wonderfully well unfavor- 
 able conditions and such agents as chemicals, but are killed 
 by strong solutions of salt, as pointed out in Chapter III. 
 They live well in shallow water or moist earth, in which 
 they come near the surface or go deeper with the rise 
 and fall of moisture. 
 
 Drinking Water. 
 
 Drinking water may become a source of infection, but 
 the probabilities of getting any considerable number of 
 larvfB in this way seem pretty remote on account of the 
 amount of contamination that would be required (less than 
 one part feces to one thousand) to maintain the life of the 
 larvae until they reach the encysted stage, and especially in 
 view of the fact that the larvse soon sink in water. Water 
 containing larvae would have to be stirred up just before it 
 is drunk to become a source of infection. Kef erring to this, 
 Stiles remarks that, ''granted that they do sink in water, a 
 water bucket in a well also sinks, and the water from sur- 
 face wells frequently contains sand particles that are 
 heavier and larger than uncinaria larvae; hence we can not 
 altogether ignore drinking water as a source of infection." 
 Leichtenstern showed that infection by mouth can occur by 
 
76 HOOIvWORM DISEASE. 
 
 administeriiig per os capsules containing the larvae. In 
 about six weeks ova of the parasites appeared in the feces 
 of the patient. These experiments with ankylostoma have 
 been repeated and confirmed with nncinaria Americana by 
 Claude A. Smith and others in this country. 
 
 Food. 
 
 Food that has been contaminated with infected mud or 
 water, or that has been handled with dirty, infected hands, 
 may become a source of infection. Smith noted the habit 
 the encysted larv« have of crawling up along the sides and 
 cover of a culture dish, which suggests another way in 
 which certain food may become infected. Larvae may 
 crawl up on the leaves, stalk, or fruit of such vegetables as 
 lettuce, celery, strawberries, water cress, etc., that are eaten 
 raw, and they may be swallowed when these are eaten. No 
 ordinary washing could be expected to remove all of the 
 larvae. The frequent practice of defecating in the barn- 
 yard, where the feces would be mixed with the barnj^ard 
 manure and frequently used to fertilize the vegetable and 
 other crops, may possibh^ be a source of infection. In the 
 country the vegetable garden is usualh" located behind and 
 near the house, and is one of the common places for the 
 location of the privy, if one is provided. It serves also a 
 frequent place for defecation of the women and children 
 when no privy is used. This may not rareh^ be a source of 
 the larvae getting on vegetables, and thus infecting those 
 who eat them raw. 
 
 Infection Through the Skin. 
 
 Looss, in 1898, while experimenting with cultures of 
 ankylostoma larvae, found that getting the culture on his 
 hands produced a dermatitis. Later on, finding ova in his 
 
MODES OF INFECTION. 
 
 77 
 
 feces, he concluded that he had been infected through the 
 skin. In 1903 he proved the correctness of his theory by 
 experiments. Grassi, Fieri, and Noe dropped water con- 
 
 Fiff 14 Experimental hookworm infection. Tlie soil containing the 
 larvae as it appeared on the wrist, the tendons and veins of the hand showing- 
 distinctly. (Photograph furnished by Dr. Claude A. Smith.) 
 
 taining ankylostoma larvae on their own arms. In the 
 feces of only one of them were ova found at the end of ten 
 weeks. They, therefore, concluded that Looss' theory of 
 
 cwi,iA.s^;A,K 
 
 Fig 15. Experimental hookworm infection. Shows swelling ot wrist and 
 tendonl of hand, and vesicle formation. Second day. (Photograph furnished 
 by Dr. Claude A. Smith.) 
 
 skin infection, deduced from his experiments, was not con- 
 firmed, and that their case and Looss' were instances of 
 accidental mouth infection. 
 
78 
 
 HOOKWORM DISEASE. 
 
 Looss then repeated his experiments, and established be- 
 yond all doubt that the larvae enter the skin and finally 
 reach the intestine, where they develop to adult life. He 
 placed some drops of heavily infected water on the arm of 
 a man whose feces showed that he was not infected up to 
 that time. 'The characteristic dermatitis soon developed. 
 The next day the arm was swollen, in a week the swelling- 
 subsided, and in seventy-one days ova were found in the 
 patient's feces. He also shaved the back of a dog and 
 
 Fig. 16 Experimental hookworm infection. Shows the large crust form- 
 ing over the area and the further decrease of the swelling. (Photograph 
 furnished by Dr. Claude A. Smith.) 
 
 placed on it some mud heavily infected with uncinaria 
 caninum. The animal was properly bandaged to prevent 
 mouth infection, and after two hours the mud was removed 
 and the area thoroughly scrubbed with absolute alcohol. 
 The mud contained only one-sixth as many larvae as it did 
 when applied to the dog's skin. The dog died in ten days, 
 and at autopsy an enormous number of larvae were found 
 on and in the walls of the small intestine. He infected two 
 other puppies, one l)y feeding infected milk and the other 
 by applying the infectious material to the skin. They both 
 
MODES OF INFECTION. 
 
 79 
 
 died in a few days, and their small intestines contained 
 enormous numbers of young larva?. These experiments 
 were confirmed by Schaudinn, Lambinet, Hermann, Cal- 
 mette, Tenholt, and Schiiffner. 
 
 In 1902 Bentley found in a "water sore," called in this 
 country ''ground itch," "dew poison," or "toe itch," a 
 young worm which he thought to be ankylostoma duo- 
 denale. He then made the following experiment: A cul- 
 ture of sterilized soil plus feces containing ova was made, 
 and another one containing no ova; both were properly in- 
 
 Fig:. 17. Experimental hookworm infection. Shows confluent vesicle 
 formation, with slight decrease of swelling-. (Photograph furnished by Dr. 
 Claude A. Smith.) 
 
 cubated at ordinary room temperature. A part of each was 
 gently dried for eight hours. Six hours' drying had previ- 
 ously been found sufficient to kill the larvae. After remois- 
 tening the specimens that had been dried, samples of the 
 four specimens were applied to the wrists of the subjects of 
 experiment for eight hours, and then they were removed. 
 Within fifteen hours after the application, erythema and a 
 papular eruption appeared over the spot where the living 
 larvae had been applied. Within twenty-four hours an itch- 
 ing, vesicular eruption had developed, followed by pustules 
 exactly resembling those found in the lesions of ground itch. 
 
80 
 
 HOOKWORM DISEASE. 
 
 In all tlie other cases no such lesions appeared. A re- 
 examination of the mud showed that the live worms had 
 disappeared, but that the dead ones were still present. The 
 live worms had, therefore, apparently entered the skin, and 
 their entry had been followed by lesions and symptoms sim- 
 ilar to ttiose of water sore or ground itch. 
 
 These experiments with ankylostoma have been paral- 
 leled by the brilliant work of Claude A. Smith, and the re- 
 sults found to hold good for uncinaria Americana. He 
 placed mud containing encysted larvse on the arm of a man 
 
 
 Pig'. 18. Experimental hookwoi'm infection. Sliows 1,348 uncinarite re- 
 moved from the intestines twelve weeks after the eruption on the wrist. 
 (Photograph furnished by Dr. Claude A. Smith.) 
 
 not previously infected and allowed it to remain one hour. 
 In eight minutes itching was complained of, and on remov- 
 ing the soil a macular eruption was present. The next day 
 the wrist was swollen. On the following day a vesicular 
 eruption was present, and much itching was complained of. 
 On the fifth day the vesicles had become confluent, the 
 swelling increased, and the axillary glands enlarged and 
 tender. The twelfth day no sign of the dermatitis re- 
 mained. On the eighth day an attack of sore throat, with 
 fever, developed. During the next three weeks an uneasy 
 
MODES OF INFECTION. 81 
 
 feeling about tlie stomach was complained of. Ova ap- 
 peared in the stools at the middle of the seventh week. A 
 small particle of mud was applied without the patient's 
 knowledge to the prepuce of a man about to be circumcised. 
 In four minutes he remarked that he felt as though a fly 
 
 Pig. 19. Section of sicin as seen under tlie microscope, showing" tlie 
 hookworm larvse crawling through the sliin. (After Stiles.) 
 
 was crawling over the part, and in a minute longer said he 
 felt as though his prepuce was being pricked with needles. 
 In four minutes the larvae had left the mud, as shown by 
 subsequent examination, but under a low power lens the 
 skin was seen covered with them. 
 
82 HOOKWORM DISEASE. 
 
 Smith was also able to produce lesions resembling ground 
 itch by applying an alcoholic extract of uncinaria larvae, 
 though aqueous and ethereal extracts gave negative results. 
 
 Sections of the skin, removed and hardened even in a few 
 minutes after infectious larvae have been applied, show 
 numerous larvae in the hair follicles, sweat ducts, and al- 
 ready actually in the tissues. In sections prepared after a 
 longer time has elapsed many larvae can be found deep in 
 
 Pig. 20. Larvae in axillary gland. (After Stiles.) 
 
 the skin and subcutaneous tissue, some of which may now 
 be found in caiDillary blood vessels. They possess wonder- 
 ful ability to plow through any kind of tissue in the en- 
 cysted stage, but will not attemjot to penetrate the skin be- 
 fore this stage is reached. Once in the blood stream, they 
 are carried to the right heart. Sections have been made in 
 which the larvae were found in blood in the heart cavity. 
 (Fig. 21.) From the heart they are carried by the blood 
 stream to the lungs. Here they are caught in the capillaries, 
 because they are so much larger than the smallest capil- 
 laries of the lungs and can not i:»ass through. Meeting with 
 
MODES OF INFECTION". 83 
 
 obstruction, they again exercise their ability to penetrate 
 tissue and soon get into the bronchial tubes, 
 
 Ashford and King infected the skin of a young guinea pig 
 with a very heavily infected culture, and in three hours the 
 animal died. Autopsy showed one lung solidified with 
 blood and the other one contained many larger or smaller 
 
 '*\ 
 
 • 
 
 ' ..v 
 
 
 1 J I I I 
 
 200 A^ 
 
 Fig-. 21. A liookworm larva in tlie blood in the heart. (After Stiles.) 
 
 hemorrhagic spots. Sections showed numerous uncinaria 
 larvae in these accumulations of blood. 
 
 After the larvae reach the bronchi they are carried to the 
 mouth, either as a result of the normal constant outward 
 current of the bronchial and tracheal mucous membrane 
 or by coughing. No doubt many of them are now spit out, 
 but some are swallowed. More or less larvae would be 
 swallowed, according to whether the individual spits out 
 what he coughs up. Habits vary much in this regard, as 
 is well known. No doubt this is an important factor in 
 determinino' the extent of infection in different individuals 
 
84 
 
 HOOKWORM DISEASE. 
 
 equally exposed, and, in view of this idea, it seems wise to 
 advise patients who have ground itch not to swallow their 
 sputum. 
 
 
 
 '" ■.■::..i>i; 
 
 ft'! 
 
 ":d0 
 
 •■ 1 
 
 
 ■-' ^ LH'WiKER, W 
 
 Fig. 22. Two hookworm larvae in the lungs. The one on the left is en- 
 tering the bronchus. (After Stiles.) 
 
 Larvae that are swallowed pass through the stomach, re- 
 sisting the gastric juice just as they resist other chemicals, 
 sulphuric acid, bichloride of mercury, etc., and when they 
 
 iHwiLoeii 
 
 Fig. 23. Larvae wandering up the trachea. (After Stiles.) 
 
MODES OF INFECTION. 85 
 
 reach the small intestine, the natural home of the parasite, 
 they undergo further development. 
 
 Four or five days after the larvag reach the small intestine 
 another ecdysis begins, in which they acquire a buccal cap- 
 sule. With this capsule the worm fastens on to the mucous 
 membrane by sucking in a plug of epithelium, which fur- 
 nishes his nourishment. In another four or five days the 
 last ecdysis begins and the last skin is shed. The worms, 
 about one-fifth of an inch long, now grow rapidly, and in 
 
 ^(■^ 
 
 
 mt-mm 
 
 Fig-. 24. Two larvae in tlie larynx. (After Stiles.) 
 
 six to eight weeks from the original infection they begin 
 to lay eggs, which are discharged with the feces of the 
 patient. 
 
 That infection through the skin is possible from short 
 contact with infected mud and water is proved. Every step 
 and stage of this process has been demonstrated by several 
 independent workers. Accepting this fact, it is only neces- 
 sary to consider how much, in the lives of people who have 
 hookworm disease, their skins are exposed to dirt and 
 water containing appreciable amounts of material-contain- 
 
86 hookwobjsi disease. 
 
 iug feces to realize the much greater opportunity for skin 
 than mouth infection. 
 
 Disposition of Feces. 
 
 How feces are disposed of and disseminated in localities 
 in which hookworm disease is prevalent.— Hookworm dis- 
 ease is pre-eminently a rural disease, being limited in large 
 cities to imported cases, those infected away from home, 
 and a few cases infected in the suburbs. The disease is 
 prevalent among inhabitants of small towns and those liv- 
 ing on the outskirts of the town, especially in the poorer 
 classes of people, where the same conditions conducive to 
 infection exist as in the country, but to a less degree. The 
 chief sources of infection for city people are visits to coun- 
 try towns, farms, and rural health resorts. Children, es- 
 pecially, often go to the country for their health, and return 
 infected with blood-sucking parasites, which may continue 
 to reduce their vitality and health for from seven to twelve 
 years. City children, however, are less likely to become 
 infected than the country children in the same place, be- 
 cause they are not so likely to go barefoot. 
 
 In the country there are few privies. With the better 
 class of farm and other country families and in towns 
 privies are more generally used. The objects in the con- 
 struction of the privy, however, in general, in town and 
 country are only shelter and convenience, and the sanitary 
 disposal of the feces receives no consideration. We have 
 indeed seen very few privies in country or town that were 
 not open at the back, leaving the feces just as accessible to 
 hogs, chickens, etc., as if no privy had been used. The ani- 
 mals root and scratch the feces, and thus scatter them about 
 over the ground. Not only this, but they often eat feces, 
 which pass through their digestive tract, a part being 
 digested, but the undigested material is passed many hours 
 
MODES OF INFECTION. 
 
 87 
 
 later, often a distance from the privy. If the feces eaten 
 by such animals contain hookworm ova, they pass through 
 undigested and are thus widely distributed. We are not in- 
 formed of any experiments to show whether ova will resist 
 the digestive process of other animals, but we have recently 
 
 Fig. 25. A privy from which soil pollution is being, spread by chickens 
 and swine. (After Stiles.) 
 
 made the following experiment with the chicken: A 
 chicken's feces were examined and found not to contain 
 hookworm eggs. A quantity of feces containing many un- 
 cinaria Americana eggs were fed to the fowl through a tube. 
 In thirty-six hours the chicken's feces were found to con- 
 
88 
 
 HO(JKWORM DISEASE. 
 
 tain many uncinaria eggs, which appeared unchanged. 
 Some of this material, mixed with charcoal and sand, was 
 incubated, and in twenty-four hours larvae began to hatch 
 out. This proves that the chicken may scatter infected 
 feces. Chickens will eat fresh human feces when thev have 
 
 Fig. 26. A privy in the center of a town of about 2,000 population. 
 
 a chance, and, besides this, they scatter them abuut on their 
 feet after scratching in them. 
 
 When the location of a privy is under consideration, if 
 such a place is available, a hill side or sloping joiece of 
 ground is usually selected. It results that heavy rains 
 wash the feces from under the privy, carrying them, and 
 others scattered by domestic animals, into mudholes, 
 ditches, etc. Later the barefoot boy comes along and 
 wades or plays in the water or ditch. The result will be 
 
MODES OF IXFECTIOX, 
 
 89 
 
 infection if tlie feces deposited contain ova. Only those 
 who have had proper opportunity to observe the facts, 
 chiefly by residence on the farm and in the country, will be 
 able to realize fully the possibilities along this line. 
 
 Where do the 60 to 80 percent of rural population who 
 have no privies deposit their feces, and what becomes of 
 them? This varies very much with the people, the loca- 
 
 Fif 
 
 '.7. The kind of privy in general use in small towns. 
 
 tion, their occupation, and local and family habits. Our 
 own observations of these things were made during many 
 years of residence in the country, where the class of people 
 and habits and conditions are such as to induce infection of 
 a large percentage of the population. The adults, and 
 often the children, of these families usually go to the barn- 
 yard or to the garden behind the house, or to "the bushes," 
 
90 HOOKWORM DISEASE. 
 
 or to "the thicket" if one is near by, or behind anything 
 like stumps, trees, hills, or outhouses, that will hide them 
 from the house. Often nobody else lives in sight, so it is 
 only necessary to hide from members of their own family, 
 regarding which they are usually not particular. 
 
 The children around a place not provided with a privy 
 frequently do not get as far away from the house as the 
 adults, especially the men. It is often possible to deter- 
 mine the number of children in a family by the number of 
 piles of feces in the back yard. In the latter part of the day 
 they are found partially or completely eaten up by chickens, 
 ducks, and dogs, by which it is possible that eggs, if present, 
 are again more widely distributed over the premises. 
 
 Many of the men in the country deposit their feces in 
 almost any convenient hiding place near their work. The 
 farm laborer drops his work whenever the desire seizes him, 
 and goes to "the bushes," or the "fence jam," or "the 
 gully" to relieve himself. The coal burner, belonging to 
 the worst infected class of people in the timber sections of 
 many of the southern states, defecates behind stumps near 
 his coal kiln, around which he lies and attends for thirty or 
 forty days, often barefoot. His children play around his 
 working j^lace much of the time, and assist him to pollute 
 the soil and share the results with him. Around saw mills, 
 public works, etc., the laborer usually repairs to some com- 
 monly used thicket or hiding place to deposit his feces on 
 the ground. In small towns, where many country people 
 come to market, etc., there is often some nearby thicket, or 
 gully, or barnyard to which the country people go when 
 they get "in a tight," in preference to privies, to which they 
 are unaccustomed, even if they are available. The country 
 people are more or less infected, and they thus convert these 
 resorts into veritable hotbeds of hookworm larvae. During 
 a rainy spell the barefoot boy who runs around in this 
 
MODES OF INFECTION. 91 
 
 locality is sure to cry with ground itch the next few nights. 
 AVe remember such a "gully" near a country town, and, 
 with our present information of the disease and knowledge 
 of the prevalence of it among the country people of that 
 section, we now see ample explanation for the ground itch 
 and anemia among many of the town boys who often went 
 barefoot in warm weather. The most favored parts of the 
 ''gully" were so much used for this purpose that there 
 often seemed to be no more room. 
 
 Many of the country schools are not provided with any 
 sort of a privy, and, often when they are, the latter are not 
 much used, because the children are not accustomed to them 
 at home. Usually in such instances the girls go to one 
 place and the boys to another, chosen by a kind of natural 
 selection. A thick clump of bushes, a gully, or a hollow 
 behind a hill are the places usually selected. A large per- 
 centage of the pupils in such schools are often infected. 
 They pollute the soil, which becomes a source of infection 
 and reinfection of all the barefoot children who visit it 
 during a hot, wet spell. We recall many schools and 
 churches in a country in Avhich much hookworm disease 
 exists, where the sanitary conditions were exactly as 
 described. Ground itch was a common trouble, and every 
 boy knew what it was — most of them from oft-repeated 
 personal experiences. The coming of railroads, develop- 
 ment of the country, and introduction of people accustomed 
 to the use of privies, and to more general wearing of shoes, 
 has reduced the anemia, once very prevalent, to an appreci- 
 ably smaller degree. 
 
 Miners working sometimes deep underground often defe- 
 cate in the mine, usually in some corner not being worked at 
 the time. The temperature and moisture are favorable for 
 hatching and development of the infectious larvae. Mud 
 and water of the mine become infected, and frequently get 
 on the hands and feet of the laborer. 
 
92 HOOKWOEM DISEASE. 
 
 A\^e have seen that, in the case of the class of people who 
 are infected, their feces are pretty widely scattered about 
 where they work and stay. It is only necessary to call at- 
 tention to the very general practice of these people of going 
 barefoot during the summer. This often is not realized by 
 the city resident, who seldom sees barefoot j^eople. The 
 children go barefoot often until they are fourteen, fifteen 
 or more years old, and often during the warmest weather 
 the adults of the family enjoy this pleasure and saving also. 
 They wear their shoes when ihej go away from home; so 
 one must see them at home to see them as they really are. 
 In these rural districts where shoes are not so generally 
 worn we have often seen children, and even grown people, 
 walking to church barefoot, carrying their shoes in their 
 hands or on their shoulders. Their Sunday shoes often 
 hurt their feet, which are unaccustomed to shoes. When 
 they get near the church they sit down by the roadside and 
 put on their shoes. These facts will be verified by anybody 
 familiar with the habits and customs of the inhabitants of 
 these remote rural districts where hookworm disease flour- 
 ishes most. 
 
 It must be remembered that the conditions of shade, 
 moisture, and favorable temperature required for the ex- 
 tensive development of the larvae to the infectious stage 
 occur only a few times a year — during long rainy spells. 
 These wet spells also furnish the condition in which the 
 barefoot individual has more or less mud and water on his 
 feet all day. Those who wear shoes step in mud and water 
 that may run in leaky shoes. If such mud and water con- 
 tains larvae, they will reach the foot in this way. The pos- 
 sibility of infection through wet shoes free from holes is 
 suggested by a recent experiment made by Bass. He placed 
 a culture of encysted uncinaria Americana larvae, grown in 
 a mixture of feces and charcoal, on one side of the arm part 
 
MODES OF INFECTION. 93 
 
 of a kid giove that had been soaked in water. On the oppo- 
 site side he placed some mud made of sterile soil and water. 
 After three hours the mud was removed, and on examina- 
 tion four living and two dead larvas were found in it. Walk- 
 ing in infected mud would furnish similar conditions, and it 
 is, we believe, possible that infection may occur in this way. 
 It is possibly an ex]3lanation of the few cases of hookworm 
 disease in people who do not know of having had ground 
 itch. 
 
 It has been seen that experimental inoculation with un- 
 cinaria larvae gives rise to sym^Dtoms identically like those 
 of ground itch or dew poison. Ashford and King obtained 
 a history of ground itch in 90 percent of their cases. This 
 condition is not so clearly described technically for the 
 diagnosis to carry with it any clear cut picture or idea of 
 disease to the uninitiated, but every country boy, or man 
 who was a country hoj, knows what ground itch or toe itch 
 is, and to him these terms mean a definite clinical condition, 
 which he knows when he sees or feels it. We have not ac- 
 curate tabulation of our cases with relation to this symp- 
 tom, but we have made it a point to inquire about it in 
 several hundred cases. We are certain over 75 percent 
 gave a history of having had it. Onh^ mild cases give a 
 negative history, and probably had infections too mild for 
 them to recognize as the ground itch. 
 
 We believe we are justified in concluding that the real 
 source of hookworm infection is always the feces of in- 
 fected persons, and, further, that the onlj- practical mode 
 of infection is by the skin. AYalking barefoot in infected 
 mud and water is the chief way in which infection gets to 
 the skin. Proljably next in importance is infection through 
 leak}^ and wet shoes. Other modes of infection are pos- 
 sible, and no doubt do occasionally occur, but compara- 
 tively they are of little importance. 
 
CHAPTER V. 
 
 PATHOLOGIC ANATOMY AND PATHOLOGY. 
 
 The anatomic changes caused by hookworm can be partly 
 studied during life in the blood, and the changes in that 
 fluid will be briefly described in this chapter on account of 
 their close relation to the theories of the disease. The con- 
 dition of the blood is also referred to in greater detail in 
 Chapter VI, among the syni23toms of the disease. 
 
 Post-Mortem Appearances. 
 
 Skin. — The skin of a hookworm subject is pale, sallow, or 
 even lemon color, and waxy, so that the l)ody may resemble 
 a wax figure. (Ashford and King.) 
 
 The body shows varying states of development, as will be 
 described more fully under symj)toms. Emaciation is not 
 always marked, as Wucherer noted. The subcutaneous fat 
 is often well preserved, pale, and yellow. The mesentery, 
 omentum, mediastinum, and pericardium are often unusu- 
 ally fat. The muscles are jDale, sometimes brownish gray 
 (Ashford and King), soft, friable, and bloodless. All the 
 organs show great lack of blood. Serous etfusions, on the 
 other hand, are usually present. They are most frequent 
 and most marked in the abdominal cavity and lower ex- 
 tremities, but general anasarca is also sometimes present. 
 Straw-colored fluid may be found also in the pleural cavi- 
 ties, pericardium, and ventricles of the brain, and there is 
 not infrequently edema of the lungs. Sand with saw edema 
 of the glottis. 
 
 The heart is sometimes small, but generally enlarged, 
 dilated, and with more or less secondary hypertrophy, es- 
 
 94 
 
PATHOLOGIC ANATOMY AND PATHOLOGY. 95 
 
 pecially of the left ventricle. The subepicardial fat is often 
 well preserved. Post-mortem coagula may be either soft 
 and red, or pale and gelatinous, and the heart cavities and 
 arteries may also contain pale liquid blood. Accidental 
 valvular lesions are sometimes found; more frequently there 
 are dilatations of the tricuspid and mitral valve from mus- 
 cular weakness. Sandwith found the mitral markedly 
 changed in 12 percent of cases. 
 
 The heart muscle is flabby, pale, sometimes showing small 
 or even large bright yellow areas on transverse section of 
 the papillary muscles. 
 
 There is often sclerosis of the arteries, even in young sub- 
 jects. Similar changes may affect the cardiac valves, es- 
 pecially the mitral. Ashford and King have observed such 
 changes with only slight anemia. 
 
 The lungs are bloodless and often edematous, as stated 
 above, and sometimes the seat of hypostatic congestion. 
 
 The spleen is usually not enlarged, sometimes small, soft, 
 and with wrinkled capsule. Sandwith found it enlarged in 
 one-third of his cases in Egypt. It is sometimes tough, 
 sometimes friable. In the pulp large numbers of eosino- 
 phile cells may be found. (Yates.) 
 
 The kidneys are pale and large; the capsule strips easily 
 and shows a mottled anemic surface; the cut section is 
 slightly fatty looking, and often shows traces of parenchy- 
 matous or interstitial inflammation and fatty degeneration. 
 The kidneys are sometimes amyloid. Sandwith finds the 
 changes so typical as to suggest the term "ankylostoma 
 kidney." Granular contracted kidneys with cysts are often 
 noted, but are accidental findings. 
 
 The liver is usually not greatly enlarged, but rarely 
 smaller than normal, pale or bright yellow, or brownish or 
 greenish yellow, and greasy looking. The tissue is brittle 
 and fatty. Amyloid degeneration is rare. Daniels found 
 
96 HOOKWORM DISEASE. 
 
 an excess of iron-containing pigment, but Gutierrez could 
 not confirm this. Yates, in a severe case, found necrosis 
 about the central veins. 
 
 The pancreas shows no constant change. Some authors 
 have thought it enlarged. 
 
 The stomach is often dilated, sometimes enormously so, 
 especially in countries where bulky diet is the rule. Chronic 
 gastritis in various degrees is commonly found. Hemor- 
 rhagic erosions have been described by Eoth. Ashford and 
 King occasionally found hookworms free in the cavity of 
 the stomach, and Gutierrez found several adherent. But- 
 terworth (Journ. Amer. Med. Assn., Aug. 21, 1909) has 
 reported a case in which a large hair cast was found in the 
 stomach of a girl 8 years old severely infected with hook- 
 worm. 
 
 Intestines. — Sometimes dark red or slate-colored areas 
 can be seen through the serosa, and sometimes, but rarely 
 on the whole, blood may make the intestine look dark. In 
 severe cases of long standing, however, these may not be 
 present, so that Ashford and King did not find even bloody 
 mucus. Apparent contractions, such as AVucherer de- 
 scribed, are for the most part accidental, but thinning of 
 the walls is likely to occur in severe chronic cases, and 
 Craig saw almost complete obliteration of the valvulae 
 conniventes. 
 
 In the examination of hookworm subjects for exact scien- 
 tific purposes it is advisable to make the autopsy as early 
 as possible, and the body should not be chilled, as the hook- 
 worms are more likely to remain alive in the warm body. 
 The inspection of the intestines should be made first, after 
 opening the body. The intestine may be ligated in small 
 lengths, and each length opened in a vessel of warm water. 
 The sections of intestine may at once be placed in preserv- 
 ing solutions, and the contents of the intestine, with the 
 
PATHOLOGIC ANATOMY AND PATHOLOGY. 97 
 
 warm water in wliicli the gut was opened, examined for free 
 worms. In the majority of cases it is enough to o^Den the 
 intestine carefully on a flat surface and spread it out for in- 
 sjDection before washing it with water. 
 
 The contents of the duodenum, jejunum, and even the 
 ileum are sometimes blood-stained. Besides the blood and 
 the usual material, there is an excess of mucus, worms, and 
 ova, and Charcot's crystals. 
 
 The mucosa is often covered with thick tenacious mucus, 
 sometimes stained red to chocolate color by blood. The 
 Peyer's patches and solitary nodules are often swollen. 
 Ecchymoses and small erosions are frequent in the experi- 
 ence of most observers, varying from 3 to 4 millimeters in 
 diameter or even larger. In some cases they are very nu- 
 merous, giving a speckled appearance to the mucosa, as 
 Whipple states. The lesions are usually the same level as 
 the surrounding tissue, but may be swollen, as in the 
 frontispiece. In the midst of the red area is a small 23ale 
 elevation, at the summit of which the worm may be seen 
 adhering, or the hole caused by its bite after the worm 
 has fallen away. There may be considerable dark red or 
 slate-colored pigmentation around the lesions, from old 
 congestion and hemorrhage, and dense induration of the 
 wall. Strong, and also Yates, found extensive eosinophile 
 infiltration in the mucosa, submucosa, and even the muscu- 
 lar coats. 
 
 The hookworms are found in various parts of the small 
 intestine, from the stomach to the lower ileum. Ashford 
 and King found most in the upper and middle part of the 
 jejunum; Allen J. Smith in the duodenum, jejunum, and 
 upper part of the ileum; Tenholt in the lower part of the 
 small intestine; Sandwith within 2 meters of the pylorus, 
 as a rule — the lowest 6.30 meters. In one case he found 
 1,353 out of 1,524 worms in the first two meters of the gut. 
 
98 HOOKWOEM DISEASE. 
 
 They are found free or attached, varying much according 
 to circumstances. Sandwith in one case found ' ' 217 out of 
 863 worms attached to the mucosa; 645 were free, 16 
 were alive, and one couple in copulation." Ashford and 
 King and their colleagues in Porto Eico did not find many 
 attached. In one case they found 83 in the stomach ('' pos- 
 sibly dislodged in the manipulation"), 163 in the duo- 
 denum, and the rest in the jejunum. In some cases very 
 few worms are found at autopsies; Sandwith, in a case with 
 six bites in the jejunum and ileum, could find no worms. 
 As regards position of the worms in the intestine, Sandwith 
 suggests that in old cases the duodenum is riddled from 
 former bites, so that the villi get ^' eaten away" and the 
 worms prefer the jejunum. He found 6 cases out of 18 with 
 less than 10 worms, no thymol having been given previ- 
 ously. 0. Baker explains the small number of worms some- 
 times found post-mortem on the analogy of rats leaving the 
 sinking ship — not without reason, as some other helminths 
 seem to leave their quarters in case of severe illness of the 
 host. Sandwith suggests that in severe cases the "half 
 starved worms are dislodged by purges or repeated attacks 
 of diarrhea." 
 
 The ecchymotic spots mentioned above are in some cases 
 up to 1 centimeter in diameter, or even the size of a silver 
 dollar. In the center of the hemorrhagic spots the worms 
 are frequently found — the head and sometimes half the 
 body buried in the mucosa. The males especially are fre- 
 quently found almost buried in the mucosa, so that when 
 removed, an operation often requiring considerable force, 
 long narrow depressions mark their former positions. 
 Sometimes there are minute holes, like pin-pricks, in the red 
 areas. Many of the hemorrhagic areas are without worms, 
 but show minute erosions or ulcers % millimeter in diam- 
 eter. Though many observers have found numerous 
 
PATHOLOGIC ANATOMY AND PATHOLOGY. 99 
 
 hemorrhages, it must be emphasized that they vary. Fearn- 
 side found congested areas in 60 percent of 78 cases. 
 Whipple found hemorrhages often. Looss found the worms 
 attached without hemorrhages more often than not, and he 
 found hemorrhages especially in recent cases. Ashford 
 
 Fig. 28. Blood cyst below the mucosa of the jejunum, with cross sec- 
 tion (a) of included hookworm. (After Whipple.) 
 
 and King say (1904) : "In our autopsies the feeding ground 
 of uncinaria Americana can easily be passed over without 
 being noted." 
 
 Although one might expect the hemorrhages to be in pro- 
 portion to the number of worms, there are reasons for 
 anticipating variations from a simple ratio. Usually there 
 are many more bites or lesions than worms. Sandwith 
 found 250 worms and counted 575 bites in one case. Leich- 
 tenstern pointed out that young ankylostoma change their 
 position more frequently than old ones. Like other hel- 
 
100 HOOKWORM DISEASE. 
 
 minths also, coitus is likel}^ to be associated with change of 
 location, and active ovulation with voracious feeding, pos- 
 sibly also with migration. 
 
 From the time of Bilharz, cysts in the submucosa, con- 
 taining blood, have been described. Whipple found them 
 not infrequently, measuring 5 to 10 millimeters in diameter, 
 and gives photographs of sections. He also found hook- 
 worms in the cysts in 7 cases. The colon sometimes con- 
 tains tarry feces. 
 
 Among rare findings in the intestine may be mentioned 
 the perforating ulcer of the duodenum, described by Wil- 
 liams. Wucherer noted adhesive j)eritonitis ; amyloid de- 
 generation of the villi was seen by Baumler. 
 
 Other parasitic worms are not rarely found in cases of 
 hookworm infection, especially ascaris, oxyuris, trichiuris, 
 and anguillula. Ameba and other protozoa are not rarely 
 present in tropical and subtropical countries, including the 
 southern United States. 
 
 The bone marrow is pale, sometimes lymphoid and gray- 
 ish red; sometimes gelatinous or fatty. In the lymphoid 
 marrow nucleated red cells and other evidences of increased 
 blood formation are present. 
 
 The mesenteric glands are often hyperemic and enlarged, 
 and reach a diameter of 2 or more centimeters. 
 
 The hemolymph glands were found by Gutierrez as large 
 as hazelnuts, of the type of splenolymj^h glands. 
 
 Edema of the brain is not uncommon in severe cases. 
 Meningitis has been observed sometimes, with extensive 
 effusions into the ventricles, as in the child of 9 years, de- 
 scribed by Ashford and King, dying with 8 percent hemo- 
 globin and 720,000 red corpuscles per cubic millimeter. 
 
 The changes in the blood, in general, in cases that come 
 to autopsy are as follows: pale color, watery consistency, 
 so that the blood may resemble blood-streaked serum. It 
 
PATHOLOGIC ANATOMY AND PATHOLOGY. 101 
 
 coagulates slowly and imperfectly. The specific gravity is 
 reduced. The total bulk, according to Boycott and Hal- 
 dane, is increased. 
 
 The hemoglobin varies from a point too low to read in the 
 ordinary apparatus to about 50 percent. 
 
 The number of red cells is reduced, but less in proportion 
 than the hemoglobin, so that the color index is low. There 
 are rare exceptions to this. The red cells vary in size and 
 shape. Polychromatophilia, normoblasts, microcytes, and 
 macrocytes, but rarely megaloblasts, occur. 
 
 The leucocytes are usually increased, from twice to sev- 
 eral times the normal, in cases of comparatively short dura- 
 tion. In older and very severe cases there is sometimes 
 leucopenia of moderate degree. The leucocytes are chiefly 
 remarkable for the increase of eosinophile cells, but the pro- 
 portion of them varies very much — up to 72 percent, as in 
 a case of Leichtenstern, and in severe cases, near the end, 
 may be about normal or even lower. 
 
 The blood changes in hookworm disease, in brief, are 
 those of secondary anemia plus eosinophilia. The state- 
 ment so often made, that the blood resembles that in per- 
 nicious anemia, is based on imperfect knowledge of both 
 conditions, and has come down from a time when the blood 
 was examined much less minutely than at present. 
 
 Pathology. 
 
 The relation of the hookworm to the various anatomic 
 and functional alterations in hookworm subjects is not yet 
 thoroughly understood. The nearest and simplest explana- 
 tion is that the worms cause great and sometimes protracted 
 loss of blood, and that this interferes with nutrition in 
 many ways directly and indirectly, including degeneration 
 of the walls of the blood vessels. The fact that in some 
 
102 HOOKWORM DISEASE. 
 
 cases with severe symptoms only a few worms can be found, 
 and the additional fact that even the worms found do not 
 all or always contain blood, have led to a partial or com- 
 plete rejection of this explanation, so that others have been 
 advanced. ■» It is therefore necessary to examine the facts 
 and assign to them their probable relations. That the 
 worms cause hemorrhage can not be doubted by any one 
 who examines a number of w^orms, or who is able to make 
 an autopsy on a case that has not had too protracted a 
 course. Such a report as the following, from Ernst (1888), 
 leaves no doubt as to the presence of blood in the intestine : 
 ' ' On the mucosa of the small intestine is an unusual amount 
 of tenacious mucus, which even in the upper meter 's length 
 shows a reddish color in some places; the color becomes 
 more intense lower down, so that at a distance of four 
 meters the contents are a uniform dark chocolate brown 
 tenacious mass, the color evidently due to blood. From 
 two meters below the beginning the mucosa shows numer- 
 ous petechial ecchymoses." 
 
 Such conditions are doubtless rare, though among reported 
 cases they are not so rare as the cases of advanced anemia 
 examined by the Porto Rico Commission without finding 
 blood or ecchymoses in the intestine, or blood in the worms. 
 Most observers, like ourselves, find many or most of the 
 worms in any lot, especially the females, stained and some- 
 times stuffed with blood, so that they look deformed when 
 fixed in preserving fluids that cause much contraction. In 
 the dog hookworms practically' all the worms contain blood. 
 The absence of blood from the worms does not prove that the 
 parasites did not suck blood, for the ejection of blood has 
 long been known, having been graphically described by 
 Ernst and Leichtenstern. These observers noted in living 
 ankylostoma how "the gradually dying, but moving, worms 
 threw out of their ipouths at intervals clouds of red blood 
 
PATHOLOGIC ANATOMY AND PATHOLOGY. 103 
 
 corpuscles, like a locomotive puffing out clouds of smoke." 
 Leichtenstern saw this process especially in worms from 
 acute cases, with severe anemia and rapidly ensuing death. 
 
 Whipple more recently writes that it is ''unusual not to 
 find a few worms containing blood when the autopsy has 
 been performed within two or three hours after death." 
 ''When worms full of bright blood," he says, "were re- 
 moved from the intestinal mucosa and placed in water or 
 0.8-percent saline solution, they soon discharged the blood. 
 Under the microscope one could watch the red blood cells 
 and blood-stained fluid being poured out from the mouth 
 and anus. This explains the fact that worms found in the 
 feces or at an autopsy performed several hours after death 
 may contain very little or no fresh blood. "^ 
 
 The structure of the worms indicates that sucking is an 
 important function, and it seems certain this must have the 
 purpose of sucking fluid. If the worms fed mainly on epi- 
 thelial cells, as will be discussed below, they would hardly 
 bury themselves so deeply, nor suck into their alimentary 
 canals such masses of tissue as have been described by 
 Looss and others. The fluid, then, must be either blood or 
 blood plasma, or such other body juices as can be obtained 
 in the wall of the intestine. If the worms do not use blood 
 as food, it seems strange that they do not exercise more 
 selection and reject it at once. The process described by 
 Whipple is not, of course, to be considered as a wholly 
 natural one. Even if, as Looss points out, the blood cells 
 in the worms' intestines are not digested, it may be ques- 
 tioned whether the observations on that point are final. 
 The observation quoted from Ernst and Leichtenstern sug- 
 gests that the blood corpuscles are not chiefly desired, but 
 the plasma, the digestion of which is much more difficult 
 
 iWhippl*?, G. H. : "Uncinariasis in Panama," American Journal of tlie Med- 
 ical Sciences. July, 1909. . 
 
104 HOOKWORM DISEASE. 
 
 to observe than that of the cells. Whipple calls attention 
 to the worms living in "worm cysts" in connection with the 
 matter of blood-feeding. In these cysts the worms live for 
 several days and remain vigorous. When the mucosa is 
 fairly normal, as Whipple says, it is reasonable to suppose 
 the worms feed chiefly on blood. When the mucosa is 
 anemic, thickened, and infiltrated, the worms may live 
 chiefly on the epithelium and mucosa. 
 
 Even if the worms live wholly on blood or blood plasma, 
 the loss due to their feeding in a short time would not need 
 to be very great. According to Lutz' estimates, 1,000 
 worms, a number often present in a single case, weigh 4 
 grams. If each worm took its weight of blood — not per- 
 haps an inordinate amount — the loss at one time would be 
 trifling, but, repeated day after day, might easily be of con- 
 sequence to the host. It would not be so to a well-nour- 
 ished individual, consuming much more than his need of 
 blood-forming food, but to one living close to his margin of 
 nourishment, or with gastro-intestinal disease that limited 
 nutrition, or with insufficiency of the blood-forming organs, 
 it would before long lead to a definite anemia. 
 
 But the loss of blood is greater than the greatest need for 
 food on the part of the worms. As was stated above, the 
 worms bite often and in various places. They cause a flow 
 of blood that can sometimes be recognized in the stool by 
 the naked eye, or by chemical tests, and that can often be 
 found post mortem. There is evidence that worms them- 
 selves produce a substance that furthers the hemorrhage. 
 Sabbatani had suggested that in many, perhaps all, blood- 
 sucking animals such substances exist. A. J. Smith pre- 
 dicted their occurrence in necator. L. Loeb had shown 
 that the intestinal mucous membrane and the mucus cover- 
 ing it have a strong effect in accelerating coagulation, so 
 that ordinarily bites like those caused by hookworm should 
 
PATHOLOGIC ANATOMY AND PATHOLOGY. 105 
 
 not bleed much. Loeb and Smith fomid that ankylostoma 
 caninum produce a substance that delays coagulation; usu- 
 ally for many hours, sometimes for twenty-four hours or 
 longer. The substance was found especially in the an- 
 terior half of the bodies of the worms, but it could not be 
 determined where it was produced — in the glands of the 
 head, neck, or esophagus, but probably the esophageal 
 glands, as suggested by Smith, or the head glands. The 
 large size of these glands suggests an important function. 
 Control experiments with round worms and a tenia were 
 negative — in fact the coagulation was accelerated by the 
 products of the worms in question. Liefmann investigated 
 with reference to the presence of a substance inhibiting 
 coagulation in ankylostoma caninum, but found none in two 
 out of three observations. He thought the inhibition was 
 brought about by the co-operation of peptone and pancre- 
 atic secretion. Loeb and Smith (1906) deny this latter, for 
 various reasons not necessary to state. They admit that 
 there may be variations in the amount of the coagulation- 
 inhibiting substance in different worms and in different 
 lands. Loeb and Smith also found the substance was weak- 
 ened by boiling. 
 
 From the biting and sucking, and the accidental hemor- 
 rhages, there is a loss of blood in hookworm disease that 
 varies with the number of worms and their age and activity. 
 The loss will affect the host partly in proportion to its ex- 
 tent, but partly in proportion to his resistance to the flow 
 of blood from the bites, and partly to his power to make 
 new blood. The larger the number of worms, and the less 
 active the host's nutrition and blood-formation, the more 
 rapidly and more severely will anemia follow. 
 
 The process is not unlike that seen in some cases of bleed- 
 ing hemorrhoids or gastric ulcer, or other local diseases 
 with oft-repeated hemorrhages. In these we got blood 
 
106 HOOKWOR^M DISEASE. 
 
 changes much like those of hookworm disease — practically 
 identical in fact, with the exception of eosinophilia — low 
 hemoglobin, low color index, increased water, or so-called 
 chlorotic blood changes, poikilocytosis (with variations in 
 the size of the red cells), and sometimes normoblasts, but 
 rarely megaloblasts. Pnfiiness of the subcutaneous tissue, 
 or even dropsy and anasarca, follow as the result of the 
 hydremia. Nutrition suffers in many respects — partly due 
 to the anemia and partly to the consequent malnutrition of 
 the blood vessels. 
 
 Even the more severe changes can be explained on the 
 ground of prolonged loss of blood. Compensation is main- 
 tained as long as possible, but, when the loss of blood con- 
 tinues too long, the blood-forming organs may react as they 
 do in pernicious anemia or in so-called aplastic anemia, 
 from perversion or paralysis of their functions. 
 
 The existence of hemolytic toxins has been assumed very 
 often in hookworm disease on account of the discoveries in 
 bothriocephalus anemia. But the blood changes in the case 
 of infection with the broad tape worm are very different 
 from those in hookworm disease — so the analogy is not a 
 good one. 
 
 Gabbi and Vadala (1903), Goldmann, Preti (1908), and 
 others have asserted the production of hemolytic poisons 
 by hookworms. Allesandrini thought glands in the an- 
 terior part of the body produced hemolytic poisons that 
 caused hyperemia. Romani, who has done much experi- 
 mental work, found the serum of ankylostoma subjects 
 hemolytic to chickens and rabbits, but not to normal or 
 anemic human subjects. He even found the red blood 
 cells of ankj'lostoma anemia more resistant to rabbit serum 
 than those of healthy men, but, on the other hand, the blood 
 serum of ankylostoma subjects injected into the veins of 
 rabbits produced toxic symptoms and hemoglobinuria in 
 smaller doses than the serum of healthy men. 
 
PATHOLOGIC ANATOMY AND PATHOLOGY, 
 
 107 
 
 Loeb and Smith (1904) found no evidence of hemolysis in 
 extracts of dog hookworms (ankylostoma caninnm). 
 
 Whipple points out some of the difficulties in the way of 
 accepting the idea of hemolysis from the conditions in the 
 blood cysts already mentioned, and shows the need of 
 wholly new experiments in order to prove the hemolytic 
 theory. As he points out, the worms often "remain in 
 
 Fig. 29. Hookworm in thie submucosa, with very little extravasation of 
 blood. Cross section of tlie body of a female worm. (After Whipple.) 
 
 these submucus blood clots for a few days at least. The 
 worms are not injured by their stay, yet there are well-pre- 
 served red blood cells in all parts of the cysts." The worm, 
 therefore, "causes the loss of more blood through damage 
 to the mucosa than it can hemolyze under favorable con- 
 ditions. It does not seem likely, therefore, that this same 
 worm could secrete a hemolytic substance which, taken up 
 by the human intestine, could act on the circulating blood, 
 
108 HOOKWORM DISEASE. 
 
 where conditions would be less favorable for hemolysis than 
 in the blood cysts." Whipple has also shown that the 
 worms contain a very weak hemolytic principle which is 
 active in vitro, but is demonstrable only in concentrated ex- 
 tracts of ^le hookworm. Hemolysis takes place very slow- 
 ly, very little being observed in six hours. The hemolysin 
 is present in all i^arts of the worm, and probably is related 
 to its alimentary canal and its digestion of the host's blood. 
 Whipple's observations on hookworm were controlled by 
 experiments on various other worms, dog hookworm, whip 
 worms, and round worms. His negative findings confirm 
 those of Loeb and Smith. 
 
 Preti claims to have discovered a hemolysin in the old 
 world hookworm, not soluble in saline, but freed and made 
 soluble in water by trypsin. He believes the substance is 
 similar to that of bothriocephalus latus, but, as we have 
 said before, the blood changes in the two conditions are so 
 dissimilar that further proof and control observations are 
 much needed. 
 
 The pigmentation of the liver and spleen have been 
 looked upon as evidences of a hemolysin secreted by worms 
 and absorbed by the host, but, as similar changes occur in 
 many secondary anemias — tuberculosis, for example — the 
 pigmentation can not be looked upon as proof of a hemolytic 
 poison. 
 
 It is necessary to discuss the other effects of the hook- 
 worms upon the intestinal wall. Besides blood, the worms 
 are supposed to eat mucus — in fact, Sangalli believed that 
 to be their normal food. 
 
 Looss has shown a much more important source of food — 
 the intestinal mucosa itself. He points out that the worms 
 do not merely bore into the intestinal wall, as if for the pur- 
 pose of applying suction, but that they cause an actual de- 
 fect in the tissue. The mass of tissue, then, drawn into the 
 
PATHOLOGIC ANATOMY AND PATHOLOGY. 
 
 109 
 
 esophagus, as shown by the beautiful photographs of Looss 
 and the Porto Rico Commission, is not mucosa alone, but 
 largely submucosa, a plug of which reaches far down the 
 esophagus or even into the intestine, in which it can be seen 
 to break down into its histological elements. "The latter 
 form the exclusive contents of the intestine in the ma- 
 
 Fig. 30. Photomicrograph of uneinaria Americana sucking mucosa. By 
 the late Dr. W. M. Gray, Washington, D. C, from the report of the Porto 
 Rico Commission, 1906-1907. 
 
 jority of cases; in others there is an admixture of blood, 
 which varies from a few blood cells to pure blood. A per- 
 fect digestion of these corpuscles does not take place; the 
 nuclei retain their tinctorial qualities unchanged, and only 
 the plasma becomes more or less cloudy. Accordingly, the 
 intestinal mucosa itself is the food of the ankylostoma; the 
 worms eat into it, and, if thereby they accidentally meet a 
 
110 
 
 HOOKWORM DISEASE. 
 
 blood vessel, the wall of the latter becomes eroded. The 
 blood that flows out is partly swallowed, the rest escapes 
 beside the worms, forming the well-known hemorrhages." 
 (Looss.) 
 
 It is important to realize the difference between epithelial 
 cells only 'and the mucosa, including the sub mucosa, which 
 
 Fig. 31. Jejunum in a fatal case of uncinariasis, showing extensive 
 scarring and inflammation of tlie intestine, a. Bases of crypts of Lieberkiihn; 
 many polynuclear leucocytes in tlie interglandular tissue; b, muscularis 
 mucosae distorted and scarred, invaded by many wandering cells, many of 
 them eosinophiles; c, submucosa, which is much tliickened and full of every 
 type of cell — eosinophiles, polynuclears, and "polyblasts." There is much 
 scar tissue; new-formed blood vessels are seen. (After Whipple.) 
 
 Looss thinks forms the food of the worms, and we doubt if 
 the process as described takes place as often as mere blood- 
 sucking. If it did, one would expect to see much more 
 serious defects of the intestinal walls in cases with, say, 
 1,000 or 1,500 worms, and we should expect to see the worms 
 
PATHOLOGIC ANATOMY AND PATHOLOGY. Ill 
 
 destroying or undermining the mucosa, like ameba, but on 
 a larger scale. 
 
 An event that must be of greater importance than the 
 consumption of mucosa by the worms is the infection of 
 the bites. This was first emphasized by Allen J. Smith, 
 who wrote in 1904:^ ''It is possible too . . . that these 
 lesions may fail to heal, and from infection by pyogenic 
 organisms become ulcerated, small follicular ulcers, with a 
 marked zone of hyperemia, thus being produced. These 
 sometimes run together to form irregular linear ulcerations 
 in the mucous membrane." The possibility of toxic ab- 
 sorption from such ulcerative lesions can not be ignored, 
 and Smith went on to say that the type of anemia and the 
 failure to find hemolytic poisons ''by no means set aside 
 the idea of a toxin having widespread and important inter- 
 ferences with the integrity of the general tissues and of the 
 nutritive functions of the host. ' ' 
 
 Whipple believes that the "anemia may be due to the 
 poisonous products absorbed from these foci of inflamma- 
 tion in the intestine," and that this explains the fact that 
 some cases with relatively few uncinariaB may show a pro- 
 found or even fatal anemia. The case he cites in this con- 
 nection is most instructive, and we quote it in full, with 
 Whipple's deductions:^ 
 
 "A male Jamaican negro, aged 60 years, shortly before 
 his death had 15 percent of hemoglobin. There was noth- 
 ing unusual about the gross pathology of the viscera. The 
 tissues were all very pale. The heart was greatly dilated, 
 with watery, pale clots — hydremia. The lungs were pale 
 and cushiony. The liver and kidneys showed a definite 
 yellowish brown pigmentation and anemia. The bone mar- 
 row was very firjn, pink, and cellular. The jejunum con- 
 
 1 "TTncinariasis," International Clinics, vol. 2, 14th series, 1904, p. S2. 
 = Whipple: "Uncinariasis in Panama." 
 
112 HOOKWORM DISEASE. 
 
 tained between 100 and 200 hookworms, but the types were 
 not identified. The mucosa was very pale and smooth. 
 There were no notes concerning the presence of fresh blood 
 in the worms, and no notes regarding ecchymoses. We 
 can not assume that the worms were discouraged by the 
 anemia, a'bandoned the mucosa, and were carried out in the 
 feces, for we find cases with even greater anemia and many 
 hundreds of worms in the intestines. Microscopic sections 
 of this jejunum are most interesting. (Fig. 31.) The 
 mucosa shows rather short villi and crypts, with a little dis- 
 tortion of the architecture of the glands, due to an increase 
 in connective tissue. The interglandular tissue in the villi 
 and at the base of the gland tubules shows a marked infil- 
 tration with polymorphonuclear leucocytes and eosino- 
 philes, which in some fields are more numerous than 
 the mononuclears. The muscularis mucosae is thickened, 
 scarred, and infiltrated with wandering cells of all types. 
 The submucosa is thickened and scarred. It is not sharply 
 separated from the muscularis mucosse, and many poly- 
 morphonuclear leucocytes and eosinophil es are present. 
 Accumulations of large mononuclear wandering cells are 
 found about the vessels in the submucosa. The outer 
 muscle coats are normal. This is a very definite patho- 
 logical change, a picture of diffuse inflammation, evidently 
 of some duration, due to the hookworm, as evidenced by the 
 eosinophiles. 
 
 ''When one considers the amount of tissue which was in- 
 volved in this change — several feet of the jejunal mucosa — • 
 it is not difficult to account for an advanced anemia. Per- 
 haps the same explanation may hold for the liver necroses 
 which were present in this case, and similar to those de- 
 scribed by Yates in a fatal case of infection with the new 
 world hookworm. Many of the liver lobules show a ne- 
 crosis of the central half or third, where the liver cells are 
 
PATHOLOGIC ANATOMY AND PATHOLOGY. 113 
 
 quite hyaline, and wandering cells are invading such areas. 
 The other liver cells show some fatty infiltration and a 
 deposit of a finely granular, yellow pigment."^ 
 
 Many efforts have been made to isolate the poison of 
 hookworms, but hitherto without results of value. 
 
 Lussana first thought he demonstrated a toxic action by 
 experiments w^ith the urine of ankylostoma patients in 
 animals. Rabbits so treated developed anemia. Arslan got 
 similar results. But such experiments are very crude, and 
 do not permit definite conclusions, so that it is not surpris- 
 ing to learn that Crisafuli and Aporto got similar results 
 from the urine of healthy men or from those with intestinal 
 disease. Vannini found the urotoxic coefficient higher at 
 the height of the disease — 0.88 — than after treatment, and a 
 gradual fall to 0.422, but this is equally inconclusive. 
 
 Besides poisons that may be produced in the lesions in 
 the intestine, it is possible that the decomposing blood ex- 
 creted by the worms or flowing from the bites may play 
 some part in the chain of events. 
 
 To summarize this part of the subject, we suggest: 
 
 1. That hookworms cause loss of blood by sucking and 
 subsequent hemorrhage; that this alone produces the 
 anemia in many cases. 
 
 2. That infection of the bites is an important part of the 
 pathology of hookworm disease, and may be the most im- 
 portant, either from the number of the lesions or the sever- 
 ity of the subsequent bacterial infection. 
 
 3. That other toxic processes may play a part, but at 
 present they have not yet been proved to exist. 
 
 Secondary anemia and toxemia are the only conditions 
 that could cause the symptoms in all but advanced and com- 
 plicated cases, and nevertheless permit the rapid recovery 
 that follows in such cases on removal of the worms. In 
 
 1 In some cases an actual mixed infection takes place. Sabrazes has re- 
 ported a striking example of this. (Arc h. de Med. exp6r., 1907, p. 85.) 
 
114 HOOKWORM DISEASE. 
 
 these it is obvious that the lesions in the intestine are not 
 such as could account for the anemia, for in that event, 
 though compensation could occur, it would hardly be so 
 closely related to causal treatment and so rapid as the im- 
 provement that follows thymol. 
 
 Anemia, with its important effects on all nutritive and 
 metabolic processes, including oxygen metabolism, explains 
 most of the striking features of hookworm disease, such as 
 the physical and mental weakness; it predisposes to other 
 diseases, and renders the patient more likely to succumb 
 to those that affect the circulation when they occur as com- 
 plications. It may explain the lack of development occur- 
 ring in early life, though this is probably due even more to 
 the local lesions in the intestine. A specific infl.uence on 
 development can not be either asserted or denied, but it is 
 very desirable that investigations along the lines suggested 
 by Dr. I. I. Lemann in a case to be reported be carried out 
 in proper cases. 
 
 The cause of the eosinophilia is almost certainly to be 
 ascribed to a toxic action by the worms, but whether it has 
 any relation to the other suspected toxins must be left to 
 future observations. 
 
CHAPTER VI. 
 
 SYMPTOMATOLOGY. 
 
 There is probably no disease in which the symptoms are 
 so variable in degree as in hookworm disease. This is to be 
 expected when the mode of infection, which is fully dis- 
 cussed in another chapter, is understood. It is certain that 
 every worm that enters the body of an individual comes 
 from without, and that a patient can not directly infect 
 himself, because the eggs can not hatch in the intestinal 
 canal. The number of worms that may get into an in- 
 dividual depends on several very variable factors and con- 
 ditions, and, in fact, frequently on accident. It follows, 
 therefore, that the number of worms present may vary from 
 one up to the lethal dose for the individual patient, which 
 frequently runs up into the thousands. Immunity, both 
 racial and individual, also contributes to this variability of 
 symptoms. Fatal cases, in which only ten or twelve worms 
 were found at autopsy, have been reported, and other cases 
 have been reported that expelled over 4,000 worms, fol- 
 lowed by complete recovery. A frequent source of vari- 
 ability of symptoms is the presence of associated diseases 
 that produce more or less anemia themselves. 
 ' The symptoms of hookworm disease are due to loss of 
 blood and the effect of a toxin which may also be capable 
 of destroying blood. This blood destruction results in 
 anemia of variable degrees, and this, in turn, gives rise to 
 other symptoms, the direct result of long continued loss of 
 blood. In fact, we question whether the symptoms of hook- 
 worm infection may not all be attributable to this, except 
 possibly the eosinophilia so frequently seen. Certainly all 
 
 115 
 
116 
 
 HOOKWORM DISEASE. 
 
 the most prominent symptoms are attributable to this 
 cause. 
 
 Before taking up the description of symptoms in detail, 
 we want to impress on the reader as forcibly as we can that 
 a great mpny cases of hookworm infection present no 
 symptoms that can be recognized as variations beyond the 
 
 Fig. 32. Mother and three children, subjects of hookworm disease. 
 Prematurely old mother; youngest child also infected. (Photograph fur- 
 nished by Dr. C. C. Thompson, Columbia, Miss.) 
 
 normal. If, however, these patients with no recognizable 
 symj)toms are cured of their worms, though often very few 
 are present, they frequently gain five or ten pounds, feel 
 better generally, and even show improvement of blood 
 count and hemoglobin. 
 
 Eecently we carefully measured 
 
SYMPTOMATOLOGY. 
 
 117 
 
 and weighed llfty-six grown men with hookworm infection 
 so mild that they could not have been diagnosed or even sus- 
 pected without a fecal examination. Many of them had so 
 few ova in their feces that none could be found until the 
 specimens were centrifuged. We also weighed and meas- 
 ured one hundred and twenty-nine men of the same class 
 who had no infection. The infected averaged eight and one 
 
 Fig. 33. Family witli liookworm disease of moderate intensity, 
 grapii furnished by Dr. W. A. Dearman, Purvis, Miss.) 
 
 (Photo- 
 
 quarter pounds lighter and two and one-third inches shorter 
 than the uninfected. It is not improbable that many of the 
 infected had had greater infection in earlier life, and there- 
 fore we can not conclude that the average of weight and 
 height below that of the uninfected was due to mild infec- 
 tions altogether. A medical student, 25 years old, under 
 our observation expelled twenty-two worms from one 
 
118 
 
 HOOKWORM DISEASE. 
 
SYMPTOMATOLOGY. 119 
 
 conrse of tliymol, after which no more ova could be found. 
 He was then as heavy as he had ever been in his life— one 
 hundred and thirty-seven pounds. In thirty-seven days he 
 gained nine pounds, and felt more vigorous and more like 
 studying than he had in his recollection, though he had 
 never been sick. In fact, he said the present treatment was 
 the first dose of medicine he had ever taken. Such a pa- 
 tient can not be said not to have had symptoms, but they 
 were not recognizable. The slight diminution of weight 
 and vigor, though certainly present and caused by the in- 
 fection, was within the normal variation. 
 
 Another student had a hemoglobin percentage of 100 and 
 was as red-faced, healthy looking, muscular a man as was 
 in the class, and played on the football team as a star. He 
 had so few ova in his feces that it was necessary to use the 
 centrifuge to make the diagnosis. Two months after treat- 
 ment he weighed five pounds more than he did before, but 
 saw no difference in himself otherwise. Many of the mild 
 cases have slight reduction of hemoglobin, but so many 
 other things may cause the hemoglobin to fluctuate within 
 normal limits, and the practical methods of estimating 
 hemoglobin are so crude, as to prevent recognition of this 
 symptom in the mild cases. A reduction of hemoglobin 1 
 or 2 percent could not be recognized, though actually pres- 
 ent and caused by the infection. Ten or 15 percent would 
 be considered within the normal limits. In fact, the clinical 
 methods of estimating hemoglobin permit a variation of at 
 least 10 percent from technical inaccuracy. 
 
 With our present methods of recognizing the symptoms, 
 we would have to say that many of these mild, cases have no 
 recognizable symptoms and can not be said to have hook- 
 worm disease. They are classed as hookworm carriers, but, 
 as we have repeatedly seen, many of them improve in 
 weight, feeling, appearance, and hemoglobin after getting 
 
120 
 
 HOOIvWOEM DISEASE. 
 
 rid of what would be considered an insignificant infection. 
 We must, therefore, conclude that such cases have symp- 
 toms, but that they are so mild as to be unrecognizable. 
 The insidious and chronic nature of the disease prevents the 
 
 Fig-. 35. Hookworm case of average severity; subject 13 years old. 
 (Photograph furnished by Dr. H. H. Ramsey., Darbun, Miss.) 
 
 patient from recognizing that his health is impaired. He 
 often is healthier in every way than others who are well, 
 so far as can be determined. One of the symptoms fre- 
 quently seen in very mild infections in adults is mild diges- 
 
SYMPTOMATOLOGY. 
 
 121 
 
 tive disturbance, such as slight reduction of digestive 
 ability, tenderness, and pain and discomfort in the epigas-: 
 trium. These come on so slowly, and often have lasted so 
 long, that the patient does not recognize them as symptoms 
 
 Fig. 36. Same subject as Fig. 35. Shows slight e.dema of face and ex- 
 pression of illness. (Photograph furnished by Dr. H. H. Ramsey, Darbun, 
 Miss.) 
 
 of disease, but considers them natural. Let such a patient 
 be cured of his worms, and he notices at once the change. 
 This type of the disease in which the symptoms are too mild 
 to be recognized when looked for is usually caused by a 
 
122 
 
 HOOKWORM DISEASE. 
 
 small number of worms, but occasionally as liigii as two or 
 three hundred worms may not produce recognizable symp- 
 toms. Adults who have ceased growing have seemed to us 
 more susceptible to the effects of a few worms than vigor- 
 ous, rapidly growing children. We are unable to say 
 whether negroes maj" joresent this type, but it is quite cer- 
 
 Fig. 37. Seven-year old girl with hookworm disease. Small for age; 
 edema of face. (Photograph furnished by Dr. H. H. Ramsey, Darbun, Miss.) 
 
 tain that the small reduction of hemoglobin could not be 
 recognized on account of color. Their reputed relative im- 
 munity makes it probable that it would require a greater 
 number of worms to produce the same amount of anemia 
 and other very mild symptoms. This very mild type of 
 the disease is, we believe, the most common in this country. 
 
sy:\[ptomatology. 
 
 123 
 
 except in the heavily infected regions. Even in the latter 
 there are many of this type among the adults and the better 
 class, who are less exposed. 
 
 A mild type of the disease is next most common in this 
 country. In badly infected sections there are many who 
 
 Fig. 38. Hookworm case of average severity. Low stature, sloping 
 shoulders, no mammary development, large abdomen ; cachectic face and 
 prematurely old expression. (Photograph furnished by Dr. H. H. Ramsey, 
 Darbun, Miss.) 
 
 show only moderate pallor, lowered vitality and energy, 
 and, though the}^ are not considered sick, their hemoglobin 
 reading may be as low as 60 or 70 j^ercent. Children with 
 this type of the disease grow a little less rapidly than their 
 
1-i HOOKWOEM DISEASE. 
 
 fellows. A comparison of the weights and measurements 
 of several of this type of a given age with a corresponding 
 number of uninfected children of the same age always 
 shows the former are under weight and under size. They 
 are a littje later in reaching puberty. Even this type sel- 
 dom consults the physician for symptoms due to the disease, 
 and the diagnosis is often missed when they do come under 
 observation, unless hookworm disease is suspected and an 
 examination of feces made. Physicians practicing in hook- 
 worm districts who are fully aware of the presence of the 
 disease in their practice, and who have diagnosed and 
 treated severe cases of the disease, usually have no correct 
 idea of the prevalence of the disease of this and the very 
 mild types. They often discuss with pride their having dis- 
 covered so many cases of hookworm disease, usually rela- 
 tively very few, in their practice, when, as a matter of fact, 
 more than half of all of their patients have the disease, 
 either alone or associated with other conditions. In one 
 instance we know of, a cotton mill physician had treated 
 several cases of severe hookworm disease in the past two 
 years, and thought himself quite expert when he diagnosed 
 two cases in mill employees. About that time the manager 
 read in a newspaper that hookworm disease was the cause 
 of laziness, and, believing that all of his employees pre- 
 sented this one of the symptoms, he summoned the physi- 
 cian to examine the sixty-two boys and girls for hookworm 
 disease. He decided, after looking at them all, that the two 
 cases already diagnosed were all there were in the mill, and 
 thought it unnecessary to examine the feces of any more of 
 them. They decided, however, to send specimens from all 
 of them for examination, regardless of the doctor's negative 
 diagnosis, and of the sixty-two there were found fifty-six in- 
 fected. Many of them were, of course, very mild cases, but 
 that not a few were more pronounced is indicated by a 
 
SYlSrPTOMATOLOGY. 
 
 125 
 
 letter from the manager four months after treatment of the 
 fifty-six cases, in which he says: "The time keeper had 
 been absent nearly three months on account of sickness in 
 his family, and on his return he found that many of the 
 children had changed so much he often had to ask the 
 
 Fig. 
 about 7. 
 
 j9. Severe hookworm case; subject 14 years old, but appears to be 
 (Photograph furnished by Dr. C. W. Stiles.) 
 
 names of some whom he had previously known well. The 
 working capacity of the hands has been increased at least 
 25 percent, and I feel that the small fee I paid you is insig- 
 nificant in comparison with our gain. ' ' 
 
 We may, for convenience, recognize another type — the 
 
126 HOOKWORM DISEASE. 
 
 severe type, in which the hemoglobin ranges from 60 down 
 to 30 percent, and the i^atient is too weak and dyspneic on 
 exertion to be overlooked. He is pale, anemic, and, if not 
 an adult, his growth is interfered with. He often grows 
 very little for years, and, if the infection is kept up, the 
 patient may be no larger than a 12 or 13-year old child when 
 he is actually 20. He will continue to grow until he is 26 
 or 28 years old if the infection lasts a long time, but the 
 size attained is never what it would have been if the infec- 
 tion had never occurred. The pubic and axillary hair ap- 
 pears one, two, or even four or five years late, and the beard 
 does not start until the patient is 24 or 25 years old. We 
 know of an instance in which there were two deaths in a 
 family from what we now know to have been the very 
 severe dropsical form of hookworm disease, and several 
 other boys had this severe type. They were often crippled 
 with ground itch, and were typical anemic dirt eaters. One 
 of the boys at 14 went to live with an uncle in a small town, 
 and was thus removed from the continued reinfection to 
 which the other four were exposed. When he left home he 
 looked no better than his brothers, but at the age of 20 he 
 weighed about one hundred and fifty pounds and had a 
 pretty heavy beard. He sometimes went home and thence 
 to church with his brothers, two of them older than himself, 
 and it was comical to see them together, knowing their ages 
 and relation. One of them made a small man at the age 
 of about 27, but had little or no beard at about 30. When 
 about 35 he had grown a fairly heavy beard. If the severe 
 infection occurs, however, after the patient is fully grown 
 and the beard has come out, the latter often feels and looks 
 dry and dead, but does not disappear. In this type in 
 women menstruation is delayed, irregular, scanty, or ab- 
 sent. In certain hookworm sections in this country this 
 type is common. 
 
SYMPTOMATOLOGY. 
 
 127 
 
 Fig. 41 is from an interesting ease of this kind, re- 
 ported from Dr. Dock's clinic in the Charity Hospital, 
 New Orleans, by Dr. I. I. Lemann. The subject, 22 3^ears 
 old, was usually taken to be 13 or 14. The bony develop- 
 ment corresponded to that of 11 V2 years. The careful 
 analysis of Dr. Lemann shows that the dwarfing process 
 was general. "There is no disproportion between the 
 lengths of the limbs and the trunk; no undue size of the ex- 
 
 Fig. 40. Severe hookworm case; subject 16 years old. Emaciation; no 
 edema. 
 
 tremities or the head." The height at the time was 139.5 
 centimeters, or about four feet eight inches. 
 
 We may recognize a severe type of the disease in which 
 the hemoglobin ranges from 30 down to 8 or 10 percent, and 
 is frequently accompanied by albuminuria and dropsy. The 
 anemia, pallor, and weakness usually incapacitate patients 
 for any kind of work, and when dropsy is present they often 
 have to remain in bed. In this type death may occur from 
 
128 
 
 HOOKWORM DISEASE. 
 
 the hookworm disease alone, whereas in the previous types 
 death does not occur, except as a result of some intercurrent 
 
 Fig-. 41. Hookworm .subject 22 years old. Three hundred hookworms ex- 
 pelled two years ago; numerous ova now (1909). (Case to be reported by 
 Dr. I. I. Lemann, 1910.) 
 
 disease. This type of hookworm disease is, however, a 
 fruitful source of death by lowering the patient's vitality 
 and resistance against other diseases to which he now sue- 
 
SYMPTOMATOLOGY. 
 
 129 
 
 Climbs, tliougli uoriually lie would have recovered from 
 them. There are relatively very few cases of this type in 
 
 Fig. 42. Side view of Fig. 41. 
 
 the United States. According to the opinion of the Porto 
 Rico Anemia Commission, about 30 percent of all the deaths 
 in the island are due to this type of the disease. 
 
130 
 
 HOOKWORM DISEASE. 
 
 This arbitrary division of the disease into several differ- 
 ent types is nsefnl mainly to enable ns to convey in our de- 
 
 Fig. 43. Rontgenogram of hand of hookworm subject shown in Fig. 41. 
 (Negative furnished by Dr. A. Granger, New Orleans.) 
 
 scription of the disease a more definite idea or meaning for 
 snch terms as very mild, mild, severe, and very severe cases. 
 Each type must merge imperceptibly into the other. In- 
 
SYMPTOMATOLOGY. 
 
 131 
 
 ....or^'^^§■ 44. Rontgenogram of hand of normal man 19 years old 
 graph furnished by Dr. Thomas Morgan Rotch.) 
 
 (Photo- 
 
132 HOOKWORM DISEASE. 
 
 asmuch as the symptoms and results of the disease are due 
 chiefly, if not wholly, to anemia, we believe whatever classi- 
 fication is necessary should be based on the amount of 
 hemoglobin a patient has. We would classify cases with 
 over 80' percent hemoglobin as very mild; those with 80 
 percent to 60 percent, mild; those with 60 percent to 
 30 percent, severe; and those with less than 30 percent, 
 very severe. Ashford and King distinguish three grades of 
 the disease — slight, moderate, and marked. Their "slight" 
 cases correspond about to our mild cases, their "moderate" 
 to our severe, and their "marked" cases to our very severe 
 ones. Their summary of the symptoms under each head is 
 so complete, and yet brief, that we quote it below in full. 
 Up to this writing (1910), theirs is the only very large 
 series of observations and statistics on hookworm disease 
 due to uncinaria Americana. 
 
 "Slight cases. — Such as those who possess little or no 
 pallor, or, at best, show but an indefinable, dirty yellow 
 tinge of the skin in whites and a slight pastiness in mulat- 
 toes. There is a reduction in the normal amount of perspi- 
 ration. The appetite is apt to be capricious. Attacks of 
 gastralgia are felt at odd times, or at least a little uneasi- 
 ness in the epigastrium, a tendency to meteorism, slight 
 breathlessness on exertion, occasional palpitation of the 
 heart, dizziness, headache, lack of attention to details, and 
 a little dulling of the mental faculties. The muscles are 
 flabby, and weakness and indisposition to labor exist. The 
 hemoglobin of such persons generally lies between 60 per- 
 cent and normal, the former sometimes in spite of a good 
 color. 
 
 "Moderate cases. — These form the usual type seen in 
 Porto Rico, although, naturally, marked cases predomi- 
 nated among those applying for treatment. Here all symp- 
 
SYMPTOMATOLOGY. 133 
 
 toms noted under slight cases are more prominent. The 
 pallor is definite, the mucous membranes are paler than 
 normal, the skin is quite dry, and sweating is rare. Appe- 
 tite may be exaggerated to the point of bulimia, or even 
 perverted to geophagy. Nausea is frequent, and vomiting 
 may occur at times. The tongue is coated, and often flabby 
 and enlarged. There may be some tenderness of the epi- 
 gastrium and abdomen, with spontaneous pain and heavi- 
 ness. Breathlessness is much more easily elicited. Palpi- 
 tation of the heart is frequent and severe, and not always 
 relative to exertion. The pulse is more rapid, and is liable 
 to be weak and compressible. There is often a hemic mur- 
 mur of the heart and a little hypertrophy. The pulsation 
 of the vessels of the neck is noticeable. There is much pain 
 in the sternum and chest, with a feeling of weakness of 
 knees and legs. The patient feels sick. There is much diz- 
 ziness, especially on sudden changes of position, noise in 
 the ears, and frequent headache. The mental condition is 
 decidedly depressed, and the patient is quite passive to his 
 surroundings and appears stupid. Sometimes the patellar 
 reflex is exaggerated, but more often it is diminished. 
 There is susceptibility to cold, and tingling of the feet, 
 which frequently 'go to sleep.' The muscles are flabby and 
 a little painful. Joint pains are so common that a diag- 
 nosis of rheumatism is often made. Work is undertaken 
 with great effort. The hemoglobin is apt to be between 
 30 and 60 percent. 
 
 "Marked cases. — Here the patient has arrived at that 
 stage where fatal termination may occur at any time. The 
 pallor is very extreme. Edema of the feet and ankles 
 alone, or sometimes extreme anasarca, is seen. The diges- 
 tive disturbances have changed in character, and appetite 
 is often nil — often enormous. Some of the worst forms of 
 geophagy are here seen. Nausea and vomiting are fre- 
 
134 HOOKWORM DISEASE. 
 
 qiient. Ascites is liable to appear and become alarming. 
 Diarrhea may alternate Avitli constipation. There is dis- 
 tressing dyspnea on the slightest movement, and sometimes 
 when the patient is perfectly quiet; severe palpitation of 
 the hear^; precordial pain; rapid, weak, compressible 
 pulse, and often dilatation of the heart. Marked pulsation 
 of the vessels of the neck and of the base of the neck may 
 be noticed at some distance. There is often pulsation of 
 the great veins, with bruit-de-diable of the jugulars. Diz- 
 ziness and tinnitus aurium are extreme. There is much 
 headache and insomnia. The patellar reflex is abolished. 
 In men, impotence is an almost invariable symptom, and 
 amenorrhea in women. The intellect is much dulled; men- 
 tal processes are slow, and the patient seems confused and 
 stupid. The facial expression is melancholic and anxious. 
 Paresthesias become very marked. There is a tendency to 
 dilatation of the pupil, and blurred vision exists. The urine 
 has a low specific gravity, is abundant in quantity, and 
 usually contains no albumin. The muscles are flabby, sore, 
 and painful. Extreme weakness, even to the simulation of 
 paralysis, is observed and the patient is incapacitated for 
 labor. There may be irregular fever, with intervals of sub- 
 normal temperature." 
 
 Acute hookworm disease may occur without previous in- 
 fection, or an acute attack may supervene on a chronic in- 
 fection. These acute attacks occur in the spring and sum- 
 mer, and their symptoms will vary with the intensity of the 
 infection. If sufficient infection occurs, there will be di- 
 gestive disturbances, epigastric pains, rapid anemia, and 
 generally elevations of temperature as high as 101° or 
 101 1/2° F. One difference to be noted between acute and 
 chronic eases is that in the acute the patient looks waxy 
 white, with severe anemia, whereas in chronic cases, with 
 
SYMPTOMATOLOGY. 135 
 
 the same amount of anemia, there is a more yellow tinge 
 (^'tallow faced") to the skin, due to more or less pigmenta- 
 tion. Children with acute hookworm disease have not the 
 "pot belly" present in so many of the chronic severe cases. 
 
 Symptoms on the Part of Certain Tissues and Organs. 
 
 Blood. — Anemia is the most constant symptom of hook- 
 worm disease, and determines the severity in a given case. 
 It may vary from the slightest degree below normal to a 
 sufficient degree to label the patient. The type is almost 
 always that of a secondary anemia or chlorosis. The hemo- 
 globin ranges from 8 percent up, according to the severity 
 of the case. Most of the cases in this country range from 
 normal down to 40 or 50 percent. We have records of the 
 hemoglobin estimation in four hundred and thirty-two 
 cases occurring chiefly in Mississippi and Louisiana. The 
 lowest is 15 percent, and several records of very mild hook- 
 worm carriers are 95 and even 100 percent. The average 
 for all the cases is 67 2/3 percent. It must be understood, 
 however, that the number includes a great many very mild 
 cases. Ashford and King found in five hundred and seven- 
 ty-nine cases on entrance a hemoglobin percentage of 9 to 
 101 percent — average, 43.09 percent. Soon after infection 
 the hemoglobin falls much faster than the number of red 
 cells. In fact, it may even reach a pretty low figure before 
 they begin to decline. 
 
 The number of red cells is reduced slowly as the anemia 
 develops, but most severe cases have 3,000,000 to 5,000,000 
 cells. The average count in sixty cases reported by Ashford 
 and Kingi/was 2,406,416. We have made a blood count in 
 forty-two cases and obtained an average of 3,459,246. Forty 
 university students found to be hookworm carriers gave an 
 average of 5,246,322. The cells are pale, and stippling is 
 
136 HOOKWORM DISEASE. 
 
 generally present, but to no great extent. Normoblasts are 
 generally present, but megaloblasts are rare. Poikilocy- 
 tosis and polycliromatopliilia occur as the anemia increases, 
 but are never as pronounced as in pernicious anemia. 
 Anisocytosis is present, as in all the severe anemias. 
 
 Though this secondary type of anemia, with relatively 
 low hemoglobin percentage, giving rise to low color indices, 
 is what is generally seen, there occur a few cases in which 
 the number of red cells is reduced as much as or more than 
 the hemoglobin percentage, giving rise to color indices 
 sometimes above 1.0. We have seen an index of 1.35, count- 
 ing 5,000,000 red cells normal and estimating hemoglobin 
 with the von Fleischl apparatus. Patients with this type 
 of anemia are the most resistant to treatment, and often re- 
 main anemic as long as even very small numbers of worms 
 remain. In fact, they sometimes have only small numbers 
 before any treatment is instituted. They recover very 
 slowly, but usually finally get entirely well after expulsion 
 of all their worms. 
 
 The leucocytes are not generall}^ increased. Counts of 
 13,000 or 14,000 occasionally occur. We saw a case with a 
 history of recent severe ground itch in whom the leucocyte 
 count went as high as 19,400. The patient had fever some- 
 times as high as 101°, and no cause could be found, except 
 the hookworm disease. We have records of the leucocyte 
 count in sixty-eight cases of hookworm disease of various 
 degrees, the average of which is 8,746. 
 
 The differential leucocyte count usually shows nothing 
 abnormal, except as regards the eosinophiles. These cells 
 vary in number considerably, but without following any 
 known fixed law. Generally, their percentage is increased. 
 Leichtenstern saw a remarkable case with 72 percent. The 
 highest we have seen was 34 percent. Fifteen to 25 percent 
 are ordinary counts for our severe cases. Though most 
 
SYMPTOMATOLOGY. 137 
 
 cases have counts above normal, a few have a normal num- 
 ber. The eosinophile percentage often is not in proportion 
 to the severity of the disease. In very severe cases the 
 count is low — maybe within normal limits — and rises after 
 treatment for some time, and then again comes down slow- 
 ly. Very few patients have eosinophilia when they die. 
 The eosinophilia seems to depend on other factors than the 
 number of worms. While expulsion of all worms is fol- 
 lowed in certain instances by a normal eosinophile count 
 even before the hemoglobin has reached normal, in many 
 it is several months before normal counts are obtained. 
 The eosinophile counts in five hundred and thirty-two cases 
 of all grades seen by us give an average of 5.7 percent, but 
 nearly half of them were of the very mild type, nearly all of 
 which had only slight increase or none at all. It is to be 
 remembered that eosinophilia occurs in a variety of other 
 diseases besides hookworm disease, which detracts from 
 its diagnostic value. It is, however, present sufficiently fre- 
 quently in this disease to indicate an examination of the 
 feces whenever it is found. When, however, no increase is 
 found, hookworm disease can not be ruled out. An increas- 
 ing eosinophilia after treatment would be of favorable prog- 
 nostic value. 
 
 Joint pains. — The observation of Leichtenstern that joint 
 pains and pains in the bones occur is confirmed by Ashford 
 and King, who say that pain, especially in the sternum, is 
 an almost universal symptom. 
 
 Skin — Ground itch. — Synonyms: Water itch, water blis- 
 ter, water pox, toe itch, dew poison, dew crack, mud itch, 
 ''new sump bunches" of Cornish miners, sore feet of coo- 
 lies, "pani-ghao," "mazomorro" (Porto Eico). 
 
 Ground itch varies very much in its symptoms with the 
 intensity of the infection, the location, and the secondary 
 infection. It is now certain that it is caused by the hook- 
 
138 HOOKWORM DISEASE. 
 
 worm larvae, which penetrate the skin. Claude A. Smith 
 produced symptoms resembling ground itch by the applica- 
 tion of an alcoholic extract of the larvae to the arm of a pa- 
 tient. This experimental ground itch resembled that 
 caused by applying the larvae to the skin. The amount of 
 infection may vary, of course, from one microscopic larva 
 to several thousand, and would give rise to quite variable 
 symptoms. 
 
 Ground itch is a collective term, and, although in hook- 
 worm countries it is usually due to the larvae of those 
 worms, conditions clinically similar, at least to inexperi- 
 enced persons, may be due to other causes. Van Durme 
 and Looss have shown that strongyloides larvae can pene- 
 trate the skin just as hookworm larvae do, and our associate. 
 Dr. J. C. Gage, has confirmed this. From the experiments 
 with various species of hookworm larvae in different ani- 
 mals it is probable that various nematode larvae can pene- 
 trate the skin and set up local lesions, but not develop in 
 the body. So the larvae of the hookworms of dogs and 
 other animals may possibly cause ground itch. Similar 
 lesions may be caused by ticks, harvest bugs, sand fleas, 
 fly larvae, and other insects. 
 
 The disease is most likely to be located on the feet, but 
 the hands maj be affected, as in gardeners, miners, and 
 others whose occupation leads them to handle infected earth 
 and mud, or in children from ]3laying in infected sand and 
 mud. 
 
 In rural districts, where hookworm disease is most preva- 
 lent, little children often wear only one dress or shirt, or an 
 apron. Sometimes children in their "shirt tail" sit down 
 on infected mud and sand, and thus get infected on the but- 
 tocks. By far the most common location is the feet, and 
 between and beneath the toes. This is because infected 
 mud is squeezed in between them, and is more likely to re- 
 
SYMPTOMATOI^OGY. 139 
 
 main until the larvsB have time to penetrate the skin. The 
 lesion is also often located around the edge of the soles at 
 the juncture of the thick and thin skin. It is not so com- 
 mon on the dorsum of the feet, except just above the toes. 
 The soles are not so much affected as other parts. The 
 inner side of the sole, where there is little pressure, is a 
 favorite location. All of these places, it will be noted, are 
 those most likely to get mud on them and have it remain 
 if the child steps in it. We have seen the eruption involve 
 the legs from wading in infected water on the farm, aud it 
 sometimes comes around the ankles when muddy water 
 gets over the shoetops. A few minutes after infected 
 mud is applied, stinging of the skin occurs. This occurs 
 so promptly that little boys often learn what kind of 
 places they get ground itch from and avoid them. With- 
 in a few hours redness, stinging, and itching put the 
 victim to rubbing and scratching. Many a country boy 
 has cried and spent restless nights with his ground itch. 
 The cry then increases, there occurs more or less swelling, 
 and the itching is more intense. The desire to scratch is 
 irresistible and the satisfaction of scratching partially re- 
 pays for the unpleasantness of the disease. In twenty-four 
 to thirty-six hours small pinhead sized vesicles appear, 
 which, according to the amount of infection, may not be 
 numerous, or they soon become confluent. The vesicles are 
 common on the inner surfaces of the toes, where they are in 
 contact. - The macules which precede the vesicles where 
 the infection is very slight are larger and more painful, and 
 itch worse on the soles and thick skin. The vesicles are 
 more likely to become confluent between and in the folds 
 beneath the toes, which results in loosening considerable 
 skin. It is tougher here, and usually comes off in a thick, 
 heavy layer after a week or two, leaving the tender skin be- 
 neath. Scratching and rubbing often break the small vesi- 
 
140 HOOKWORM DISEASE. 
 
 cles, and scabbing occurs, but usually slowly on account of 
 the fact that the itching continues so intense for several 
 days that scratching can hardly be avoided. In twenty- 
 four to forty-eight hours the eruption becomes pustular, due, 
 no doubt, to secondary infection. This occurs much more in 
 certain individuals and at certain times than others, doubt- 
 less due to the conditions governing pyogenic infection in 
 general. Examination of the pus usually shows staphy- 
 lococci. Bentley found an ankylostoma larva in a vesicle. 
 The pustules are frequently ruptured, as are the vesicles, 
 and leave a raw surface, with rather profuse sticky exuda- 
 tion. This exudate sticks the socks or bandages to the foot, 
 and a part of the undressing performance every night with 
 little boys so affected is the necessary soaking of the feet to 
 loosen the adherent dressing. Deep ulcers do not occur, ex- 
 cept in the folds beneath and between the toes, where they 
 may be deep and last several weeks. Beneath the toes the 
 deep ulcers or cracks are kept up by the bending of the 
 toes, and often remain after all other traces of the disease 
 have disappeared. The toes are often glued tightly to- 
 gether by the sticky exudate, and where it remains moist 
 the skin is white and often loosened. In cases where 
 the vesicles are not ruptured, or where they are rubbed 
 off, they dry up in about five days, and in about eight 
 or ten days exfoliation and healing are complete. Little 
 evidence of the lesion now remains, except between and 
 beneath the toes, where the skin is so thick that it is not 
 shed so rapidly. Patients often trim this off, and, unless 
 the ulceration is especially deep, or deep fissures occur, the 
 healing is not delayed much beyond that of other parts. 
 
 In very intense infections, as in Claude A. Smith's experi- 
 mental case, great swelling occurs on the second and third 
 days. The lymphatic glands draining the part are often 
 swollen and tender, Looss has noted red lines running up 
 
SYMPTOMATOLOGY. 141 
 
 tlie limb — probably lymphangitis. There is local fever dur- 
 ing the height of the inflammation, but no systemic eleva- 
 tion of temperature, except in very severe cases. When 
 the disease is located on the feet, the diagnosis is usually 
 easy. In fact, nearly any country boy, or mother, or father 
 in a hookworm country knows what ground itch is usually 
 from experience, and recognizes it on sight. When located 
 on other parts of the body, the differential diagnosis often 
 can not be made from other diseases causing very similar 
 lesions. The history of exposure and the course of the dis- 
 ease help to settle the diagnosis. The prompt occurrence of 
 eosinophilia in most cases helps to strengthen the diagnosis. 
 This is present in four to five days after infection. 
 
 The color of the skin in chronic hookworm disease is usu- 
 ally pale, with a yellow tinge. This gives rise to the fre- 
 quent description, "tallow faced." In acute cases, where 
 the anemia rapidly develops, the patient is paler and whiter. 
 Exposure to the sun finally hides more or less of the 
 anemia. The pallor is generally in proportion to the 
 anemia, but this is not always a true guide. Patients with 
 60 percent hemoglobin may look better than others with 
 90 percent. In negroes the skin becomes gray or ashen 
 from severe anemia. 
 
 The skin of severe hookworm disease is often wrinkled, 
 so as to give the patient the appearance of being much older 
 than he is. This usually fills out again after proper treat- 
 ment. 
 
 Liver. — No change in this organ or its functions can be 
 made out clinically. 
 
 Spleen. — The spleen is unchanged, except in cases com- 
 plicated with such diseases as alter it, as malaria, leu- 
 kemia, splenic anemia, etc. 
 
 Respiratory system. — During the few days (first ten) 
 after an attack of ground itch, if the infection is very con- 
 
142 HOOKWORM DISEASE. 
 
 siderable, there may be cough, bronchitis, and sore throat. 
 Ex]3erimentally there occur hemorrhages into the lung 
 tissue, and it is not impossible that there may be secondary 
 bacterial infection and a condition resembling pneumonia 
 develop, [^he possibilities are illustrated by an experiment 
 done by Ashford and King. They applied a culture of un- 
 cinaria Americana larvae to the back of a four-day old 
 guinea pig. In three days the animal died. Autopsy 
 showed one lung solid with blood and the other containing 
 several hemorrhagic spots or blood cysts, many of which 
 contained uncinaria larvae. Such instances would, of course, 
 not be diagnosed as hookworm disease, but we believe the 
 possibilities are sufficiently great to warrant consideration 
 in cases of ground itch. Examinations of the sputum might 
 reveal larvae. If the blood were examined at such times by 
 the method of Staubli — dissolving in 3-percent acetic acid 
 and centrifugating — the larvae might be recovered from it, 
 as have trichinae by Herrick and Janeway. It is not clear 
 from Staubli 's (1908) article that he really found hook- 
 worm larvae. 
 
 Dyspnea. — On exertion, dyspnea is one of the most promi- 
 nent symptoms in cases with hemoglobin below 50 or 60 per- 
 cent. It often has existed so long that the patient looks on 
 it as normal for him and as a necessary part of his life. 
 This is one of the symptoms that reduces the patients ' work- 
 ing capacity, and contributes to the reputation they often 
 have of being lazy. Edema of the lungs and hydrothorax 
 are likely to be present in the severe cases, with general 
 edema. Ashford and King mention a ''dry cough" in 
 severe cases. This may be due to edema of the lungs or 
 hydrothorax. 
 
 Circulatory system. — Pulsation of the neck veins, mucli 
 increased by exertion, is frequently present in all severe 
 cases of hookworm disease. The heart, on inspection in 
 
SYMPTOMATOLOGY. 143 
 
 severe cases, shows a wide area of cardiac impulse, such as 
 is seen in dilatation from any other cause. Pulsation in the 
 epigastrium is a prominent symptom, and often this and the 
 extensive cardiac impulse attract the attention of the 
 patient. These symptoms are very much increased by ex- 
 ertion, as are also the pulsations in the neck. On palpation 
 the heaving, easily seen impulses are found to be weak. On 
 percussion the area of cardiac dullness is increased to the 
 left, but not much downward. There often is right-sided 
 enlargement. Relative cardiac dullness in many cases ex- 
 tends to the left of the nipple line and far to the right of 
 the sternum. 
 
 Auscultation generally reveals, in cases with hemoglobin 
 below 50 or 60 percent, a hemic murmur, best heard in the 
 left third interspace, but frequently heard all over and 
 sometimes beyond the cardiac area. 
 
 The pulse in mild cases is little changed, but in the 
 severer ones is weak and dicrotic, irregular, and compress- 
 ible in the severest cases, and in the latter it is rapid, 
 thready, and intermittent. The frequency increases with 
 the severity of the disease, but often is marked in mild 
 cases. The following is the pulse rate of twenty selected 
 uncomplicated representative cases from Mississippi and 
 Louisiana, between the ages of 15 and 25, and we believe 
 represents the average in hookworm patients in this country 
 who are sick enough to consult a physician: 84, 84, 89, 96, 
 98, 99, 110, 113, 114, 114, 124, 128, 128, 129, 132, 133, 141, 
 142, 146, and 148. The average of the twenty cases is 117.6. 
 The blood pressure averages below normal, and usually goes 
 lower as the severity of the disease increases. In two of 
 our cases albuminuria and nephritis were present, and the 
 blood pressure by the Riva Roci instrument, with two-and- 
 one-half-inch band, was 145 and 163. Twelve cases of 
 average uncomplicated hookworm disease over 15 years old 
 
144 HOOKWOEM DISEASE. 
 
 seen by us had an average blood pressure by this instru- 
 ment and in the sitting posture of 110. They were in de- 
 tail, 89, 93, 94, 99, 104, 106, 109, 117, 124, 126, 127, and 132. 
 
 Dig'estive system. — The symptoms relative to the diges- 
 tive systeifL will necessarily vary much on account of the 
 very great variation of the amount of the infection. In 
 severe cases the tongue is pale, coated, and often indented, 
 and occasionally shows purple lines on either side of the 
 median line, probably due to dilation of the veins. Pig- 
 mented spots on the tongue have been noted in dark-skinned 
 races. It is possible that these may be caused by larvae 
 penetrating the mucous membrane after they have come up 
 from the lungs. The shedding of the first teeth and erup- 
 tion of the permanent set is delayed sometimes one, two, and 
 three years, according to the severity and duration of the 
 disease. The teeth keep up, however, pretty well with the 
 development of other parts of the anatomy. 
 
 Following a severe attack of ground itch, sore throat 
 usually occurs in a few days. Claude A. Smith noticed this 
 in one of his experimental cases in eight days. After this 
 the patient begins to complain of pain, uneasiness and dis- 
 comfort in the epigastrium, due, no doubt, to the trauma- 
 tism and irritation of the gastric and intestinal mucosa. 
 The young larvsB penetrate the mucous membrane and pro- 
 duce considerable blood-cyst formation. If any difference, 
 the right upper quadrant of the abdomen is the seat of 
 most of the trouble. There may be tenderness, especially 
 in this region and in the epigastrium. Lutz believed this 
 was definitely connected with hookworm infection of the in- 
 testine. We have been impressed with the relation between 
 epigastric uneasiness and pain and hookworm disease. Dr. 
 J. B. Elliott, Sr., formerly professor of theory and prac- 
 tice of medicine in Tulane University, was one of the first 
 in this country to recognize the influence of mild hookworm 
 
SYMPTOMATOLOGY. 145 
 
 infection in producing epigastric pain and discomfort, usu- 
 ally of a vague and indefinite description. Several years 
 ago lie learned that a few such cases in which he could find 
 no explanation for the symptoms were hookworm carriers. 
 Often they had very few worms. He was in the habit of 
 having them examined, and the accuracy with which he 
 recognized these cases was in keeping with the character- 
 istic keenness of which he was known to be possessed by 
 all who had the good fortune to know him. 
 
 The following cases, reported b}- one of us (Bass, 1909), 
 illustrate this point: 
 
 Case 1. — J. B., aged 39, male, white, merchant, was well 
 develoj^ed and looked fairly well; had never had ground 
 itch; lived in town. He had had vague pains in the right 
 side of abdomen as long as he could remember; said he was 
 nervous and had ' ' indigestion. ' ' Pains were not related to 
 the time of eating. Physical examination failed to reveal 
 anything abnormal. There were a few eggs in the stools; 
 fourteen worms were recovered. The patient recovered en- 
 tirely and gained nine pounds in nine weeks. 
 
 Case 2. — L., aged 61, white, farmer's wife, had had no 
 ground itch. The negroes on the plantation had it. The 
 patient had had pains in the right side and uneasiness in 
 the abdomen for the past six years, not related to meals; 
 tenderness was not present. Physical examination showed 
 nothing abnormal. There were a few eggs in the stools; no 
 anemia. The patient recovered on treatment with thymol. 
 Eight months later she was still well. 
 
 Case 3. — Paul H., aged 42, male, white, lawyer, com- 
 plained of indigestion and frequent headaches. He had 
 tenderness in the right side of the abdomen. There were a 
 few eggs in the stools. The patient was relieved of indiges- 
 tion and headaches after the first course of thymol. 
 
 Ashford and King say that epigastric pain and tenderness 
 
146 HOOKWORM DISEASE. 
 
 are the most constant, most suggestive, and most clearly 
 marked of all the symptoms of the digestive tract. We do 
 not believe that this is true of the type of the disease most 
 prevalent in this country, but we have noted it in many of 
 our cases. We are also quite confident that it is a more 
 common Symptom in adults than in children, and, further, 
 that a small number of worms may produce it. If such dis- 
 comfort and mild eiDigastric pain were not so often observed 
 in other conditions, it would be a more serviceable diag- 
 nostic sjTnptom. 
 
 The appetite is increased in most mild and medium severe 
 cases, but anorexia is frequent in the severest cases. Per- 
 versions of appetite are common, even in mild cases. All 
 sorts of unnatural things are eaten, such as earth, paper, 
 slate pencils, lead pencils, coffee ''grounds," ashes, feath- 
 ers, hair, charcoal, unripe fruit, etc. We know of a woman 
 with hookworms and a history of ground itch who de- 
 veloped such a craving for laundry starch that she ate a 
 pound and a half a day. After keeping that up for some 
 months she showed symptoms of pellagra. (Case to be re- 
 ported by Dr. Bass.) Many have an abnormal appetite 
 for pickles, lemons, salt, etc., and resin chewing is common 
 among those living in the "piney woods" section. Many 
 chew hickory or other bitter bark. Butterworth's case of 
 hairball in the stomach, already referred to, illustrates the 
 extremes to which this unnatural appetite may go. Dirt 
 or clay eating is common, and the worst cases in an in- 
 fected locality are called by the natives "dirt eaters" or 
 "clay eaters." The anemia is supx)osed to be due to dirt 
 or "trash" eating, and parents often accuse their children, 
 and often whip them in spite of their denial. They think 
 the anemia is sufficient evidence of their guilt. 
 
 With the laity in hookworm sections and others the belief 
 is pretty common that eating dirt and "trash," including 
 
SYMPTOMATOLOGY. 147 
 
 various kinds of candy and sweets, and unripe or spoiled 
 fruit, is a source of worms, and hookworm families are gen- 
 erally believed to be "wormy," usually meaning they have 
 ascaris infection. 
 
 We recall an instance of an anemic family, due, as we now 
 know, to hookworm disease, in which many different reme- 
 dies were tried to break the children from eating dirt from 
 the clay of the stick-and-dirt chimney. One of the remedies 
 tried was to sprinkle urine on the chimney, but the final suc- 
 cessful one, so far as that chinmey was concerned, was rub- 
 bing over the chimney in the presence of the children a 
 large rattlesnake that had been killed on the place. The 
 fear of snakes was sufficient to cure them. These children 
 were among the most inordinate resin chewers, and finally 
 all took to chewing tobacco. Chewing tobacco is encour- 
 aged by this unnatural appetite, and we believe this partly 
 explains the very extensive use of the weed among hook- 
 worm people. Boys who do not grow well are often advised 
 by their physician or some one else to begin chewing to- 
 bacco. They do often begin to grow at this time, and we 
 have heard many a man or boy say he never took a start to 
 grow until he began to chew tobacco. There is no constant 
 beneficial result, for we have seen many of these tobacco 
 chewers who had practiced the habit for many years 
 and still had not "taken a start to grow." The reason 
 many of them begin to grow after they begin chewing 
 tobacco is, no doubt, that many of them at about the same 
 time begin to wear shoes or otherwise reduce reinfection. 
 It may, however, be possible that the tobacco juice swal- 
 lowed kills or injures the worms. It has been our observa- 
 tion that when dirt is eaten in a country having red clay soil, 
 this is generally selected, and children often get the habit of 
 picking and eating from the stick-and-dirt chimneys used 
 by the poorer class. They seem to prefer the very dry clay. 
 
148 HOOKWOEM DISEASE. 
 
 and we knew one negro woman who would bake lier clay in 
 the stove. She often made it up like bread and baked 
 several days' supply at a time. Half an ounce or an ounce 
 at a time was often used. She liked to put a small 
 piece in her mouth and suck on it for several minutes at a 
 time. When asked why she ate it she said, "I just craves 
 it." Others pick up little soft pebbles and suck on them. 
 In one instance a 16-year old anemic-looking boy, whom we 
 would now recognize as a hookworm patient, became very 
 ill, and was given a glycerine enema. He expelled in a few 
 minutes several ounces, consisting chiefly of pebbles, which 
 he then admitted he had been eating for over two years. 
 If earth were the only substance eaten, the opinion that this 
 symptom is due to an instinctive effort to supply iron and 
 manganese with which to build up hemoglobin might be 
 admitted to have some basis. Other substances are se- 
 lected often when clay is just as available. AVe saw a 
 severe case in a girl whose father had tried in vain in every 
 wa}^ possible to break her from eating coffee grounds 
 thrown out the window. She would often steal the 
 "grounds" from the pot if it was not put out of her 
 reach after the coffee was drained off, though she did not 
 drink coffee. The habit was cured in a short time by 
 thymol administration, which resulted in the expulsion of 
 several hundred hookworms. While many patients with 
 hookworm disease have the capricious appetite and the 
 habit of geophagy, there are many even severe cases that 
 never take up such habits. It is seldom that a child or 
 adult guilty of the habit will acknowledge it, due, no doubt, 
 to fear of chastisement or to shame. 
 
 A good deal of work has been done on the gastric secre- 
 tions by Japanese investigators. Yoshida (1908) gives re- 
 sults in 101 Formosans and Chinese, comparing them with 
 those in people on similar diet, and finds that in ankylos- 
 
SYMPTOMATOLOGY. 149 
 
 toniiasis the total acidity is most often normal, hyperacidity 
 rare, and subaciditv still rarer. Free HCl is usually nor- 
 mal, and subacidity more frequent than hyperacidity. No 
 exact relations between anemia and HCl could be made out, 
 but, with some exceptions, the more intense the anemia the 
 lower the free HCl. In the cases examined there was a re- 
 lation between appetite and free HCl in the stomach con- 
 tents. 
 
 Diarrhea occurs in the first few weeks of an acute infec- 
 tion in many instances, but is not a symptom of chronic 
 hookworm disease, excei^t in ver}' severe cases, in which it 
 is not uncommon. Constipation is often present, but we 
 doubt if it is more than an accidental symptom. Children 
 under the age of puberty are often "pot bellied" when they 
 have the chronic severe type. This is due to dilatation of 
 the stomach and intestines chiefly, and partly to excessive 
 mesenteric fat. Only children with chronic infections have 
 this symptom. 
 
 McG-ehee has reported a case in which hookworms, but 
 no ova, were found in an appendix vermiformis, the seat of 
 a catarrhal inflammation. 
 
 The feces contain the ova, which have been more fully 
 described in the chapter on Diagnosis. They also contain 
 minute traces of blood, which, however, can not be made out 
 macroscopically or microscopically, except in the severest 
 cases. Even the mild cases will usually give a positive reac- 
 tion for occult blood in the feces, provided a very delicate 
 test for blood is made, such as Adler's benzidin test. A con- 
 venient way of performing this test is to add to a few (5 to 
 10) cubic centimeters of liquefied feces 1 or 2 cubic centi- 
 meters of glacial acute acid and 5 to 10 cubic centimeters 
 of sulphuric ether. Mix without shaking, then pour off the 
 supernatant ether and test it by adding a few drops of 
 strong hot alcoholic solution of benzidin and 1 or 2 cubic 
 
150 HOOKWORM DISEASE. 
 
 centimeters of peroxide of hydrogen. In tlie presence of 
 blood, even in minute quantities, a blue color will promptly 
 follow. 
 
 Genito-urinary system. — The genitourinary organs are 
 delayed m their development in proportion to the general 
 developmental impairment. Boys develop later, accord- 
 ingly to the severity of the disease, and girls begin to men; 
 struate later than normal — often in severe cases this func- 
 tion is not established until they are 16 to 18 years old. 
 Amenorrhea and scanty and irregular menstruation are 
 common. There are instances in which pregnancy occurred 
 before menstruation was established. In girls the breasts 
 share the general retardation m development. 
 
 The quantity of urine is uninfluenced until the very severe 
 degree of the disease is reached, when the reduction is 
 often great and general anasarca supervenes. Albumin is 
 often present in small amounts in patients with hemoglobin 
 below 50 or 60 percent, and often in the very severe cases 
 is present in very large amounts. We have seen several 
 times from 40 to 50 and 60 percent of moist albumin hj the 
 Purdy ferrocyanide test. Casts are strikingly absent, but 
 sometimes may be seen in the very severe cases. We have 
 seen a case with 60 percent of albumin and extreme dropsy 
 in which no casts were found on repeated examinations. 
 General dropsy is common in very severe and almost all 
 fatal cases, and often is extreme. There is more or less 
 puffiness of the loose tissue of the face, feet, and legs in most 
 cases with hemoglobin below 50 percent. When hookworm 
 patients get pregnant, the tendency to dropsy is very much 
 increased by the disease, and in severe cases the swelling is 
 often great. Swelling of the labia is especially troublesome 
 as the pregnancy approaches term. 
 
 Lactation is impaired according to the degree of anemia. 
 Mothers are often unable to properly nourish their children. 
 
SYMPTOMATOLOGY. 151 
 
 The promptness with which this function improves after 
 treatment is striking — often actually faster than improve- 
 ment of the anemia. 
 
 Eyes. — The eye grounds showed changes in 7 to 8 percent 
 of cases examined by Lutz. Menche found that the tem- 
 poral half of the visual field showed obscurity. Neurore- 
 tinitis has been reported. Nieden, of Bochum, Westphalia, 
 has shown that patients with hookworm often have retinal 
 hemorrhages, such as occur in pernicious anemia. They 
 occur especially and early in the peripheral parts rather 
 than near the papilla and the macula, are punctate, often 
 in groups, without any tendency to confluence. Sometimes 
 they accompany the vessels close up to the papilla. In long 
 standing and severe cases there are larger plaques of ex- 
 travasation, with radiating edges. Along with the hemor- 
 rhages are the usual changes of anemia, such as pallor of 
 the retina, porcelain-like papilla, tortuous vessels, often 
 strongly pulsating. The disturbances of vision are due 
 rather to the general alterations than to those in the retina. 
 Asthenopia, paresis of the internal or external recti, dip- 
 lopia, vertigo, nystagmus, and hemeralopia (or night blind- 
 ness) may occur. Concentric contraction of the visual 
 fields has been noted. Nieden and others look on the retinal 
 hemorrhages as evidence of toxic processes. Stiles has 
 called attention to the appearance of the pupil. He says: 
 '^If the patient is directed to stare intently into the 
 observer's eyes, there will be noticed a symptom which it 
 is difficult to describe, but which I have found more constant 
 than almost any other noticed — namely, after a moment, 
 the length of time apparently varying slightly according 
 to the degree of the disease, the pupils dilate and the 
 patient's eyes assume a dull, blank, almost fish-like or 
 cadaveric stare, very similar to that noticed in cases of 
 extreme alcoholic intoxication." Ashford and King found 
 
152 HOOKWORM DISEASE. 
 
 dilatability of the pupil noticeable in their Porto Rico cases. 
 AVe have often noticed that the pupil dilates readily, and 
 usually remains wide, even in the presence of considerable 
 light, but this is a common symptom of all severe anemias. 
 
 Nervous system. — Nervous and mental symptoms of 
 various kinds are not infrequently present in hookworm 
 patients, and sometimes cause great diagnostic difficulty. 
 There are few, if any, nervous symptoms, however, that can 
 not be ascribed to the anemia. There is a general benumb- 
 ing of the mental faculties in acute cases, but the chronic 
 hookworm child is generally well up in mentality with 
 others of his size and vigor, but usually not equal to those 
 of his age. In the acute and very severe form the disease 
 produces often melancholia, hypochondriasis, and a careless 
 expression. Insomnia and night terrors are very common, 
 due, no doubt, to feeding and moving about by the worms, 
 which the nervous system feels more when the patient is 
 perfectly quiet, as in sleep, than when active. Somnolence, 
 on the other hand, often occurs, and the patient keeps awake 
 in day time with difficulty. Lack of ambition is noticeable, 
 and has given rise to the idea that the patient is laz}^ 
 Hookworm patients do not work as much or as well as those 
 not infected, but it is because they are sick and not because 
 they are lazy. In the last few years a great deal has been 
 said in the newspapers jokingly about the "lazy disease," 
 and, if the same amount of publication had been devoted to 
 dissemination of knowledge of the sources and the preven- 
 tion of the disease, there is no doubt that it would be less 
 prevalent today. 
 
 Signorelli (1909) reports some interesting cases. In one, 
 a boy of 10, with mild anemia, had a meningeal syndrome, 
 with headache, vomiting, neuromuscular hyperesthesia, 
 cervical rigidity, Kernig's sign, etc., cured by thymol. A 
 girl of 17, with neuralgia, especially crural, anesthesia, and 
 
SYMPTOMATOLOGY. 153 
 
 paresthesia, was quickly cured by thymol after the blood 
 count showed 30 percent of eosinophiles and the anamnesis 
 revealed previous residence in Brazil. In another case, a 
 woman of 23, vasomotor disturbances and epileptiform con- 
 vulsions were equally amenable to specific treatment with 
 thymol. Signorelli emphasizes the tendency of hookworm, 
 like the malarial parasite, to cause vasomotor abnormalities. 
 
 Austregesilo and Gotuzzo (Eio de Janeiro, 1909) call at- 
 tention to the possibility of severe psychic alterations in 
 ankylostomiasis. They report the case of a man of 26, free 
 from history of alcohol or syphilis, who became apathetic 
 and melancholic, later complained of severe and continued 
 pain in head and abdomen, and of dyspnea and fatigue on 
 exertion, and finally had delusions of poisoning. Severe 
 anemia with eosinophilia led to thymol treatment and to 
 complete recovery. In another case there were many evi- 
 dences of psychic degeneration, with loss of memory, re- 
 ligious hallucinations, and delirium of grandeur. Anemia 
 and 18 percent of eosinophiles suggested thymol treatment, 
 and complete recovery followed. In another, with hemo- 
 globin 35 percent, red blood corpuscles 3,100,000, and eosino- 
 philes 16, there was complete loss of sense of time and place. 
 Later, the condition described by Oppenheim as ''Witzel- 
 sucht" developed. The patient was ironic and sarcastic, 
 ridiculed everything and everybody. Improvement of the 
 ankylostomiasis coincided with that of the mental condition, 
 and finally both were cured. 
 
 MacDonald, in Australia (1908), has seen various perver- 
 sions besides dirt eating among hookworm patients, espe- 
 cially children, mentioning disobedience, profanity, lying, 
 stealing, drinking, forging, and sexual perversions. These, 
 of course, are not rare manifestations without hookworm, 
 but the important thing is that in the cases reported re- 
 covery followed cure of the hookworms. The youngest 
 
154 HOOKWORM DISEASE. 
 
 patient was only 8 months old. Allan has called attention 
 to the frequent association of neurasthenia and hookworm, 
 as might be expected. It would be interesting to make 
 observations on the psychic reactions of such cases of 
 various dfegrees of severity. Perhaps some of the exuber- 
 ant lawlessness of hookworm regions may be due to the lack 
 of control caused by the infection. 
 
 Sodre, and also Austregesilo and Gotuzzo, suggest that 
 the parorexia of hookworm infection is an evidence of the 
 altered mental condition, rather than the direct result of the 
 disease in the intestinal tract. 
 
 Finally, we want to emphasize the fact that hookworm 
 disease is likely to have associated with it other diseases, 
 and the symptoms of each be altered by the other. All 
 symptoms presented by a hookworm patient must not neces- 
 sarily be attributed to this disease. On the other hand, a 
 part of the symptoms in cases having other diseases may be 
 due to hookworm disease. 
 
CHAPTER VII. 
 
 DIAGNOSIS. 
 
 "The secret of the diagnosis of ankylostomiasis, like that 
 of many other diseases, is to suspect its presence." 
 (Manson.) 
 
 An absolutely certain diagnosis of hookworm infection 
 can not be made without finding the eggs or worms in the 
 feces. It is possible, however, to diagnose it symptomatic- 
 ally with reasonable certainty in most cases showing well- 
 marked symptoms, provided this disease is kept in mind. 
 The combination of the characteristic anemia associated 
 with underdevelopment, weakness, dilated heart, and a 
 history of ground itch is not likely to be confounded with 
 anything else. We can not emphasize too forcibly the im- 
 portance of this history of ground itch, or ''toe itch," with- 
 in the preceding years. In all patients from warm climates 
 presenting anemia and impaired development without 
 obvious cause this should be inquired for. Whenever a 
 history of toe itch is obtained, nothing short of thorough 
 examination of the feces for eggs permits elimination of 
 hookworm from the diagnosis. 
 
 A history of ground itch, or hookworm disease, aifecting 
 other members of an individual's family, or those living on 
 the same plantation or in the same surroundings, usually 
 indicates that the patient is also infected, though he never 
 had ground itch himself. 
 
 The history of going barefoot during the summer in a 
 locality known to be infected usually means that the pa- 
 tient is infected, though he has not had a definite attack of 
 
 155 
 
156 HOOKWOEM DISEASE. 
 
 ground itcli. So few larvae may enter the skin at a time as 
 not to produce recognizable or characteristic lesions. 
 
 In infected localities, as Tenholt found among miners 
 in infected mines, and Stiles in his journeys through the 
 southern "United States, the diagnosis of hookworm disease 
 can often be made by inspection, and will turn out to be cor- 
 rect in the majority of cases. In such places, where time 
 for examination is short, treatment may be carried out on 
 the ground of the symptomatic diagnosis and the accurate 
 diagnosis made by examining the stools for worms after- 
 ward. The diagnosis of cases can be made almost as ac- 
 curately from the great imiDrovement after thymol treat- 
 ment. This sort of diagnosis, however, can not be looked 
 on as satisfactory or scientific, nor will it discover the im- 
 portant class of hookworm carriers. 
 
 Though the diagnosis may be indicated by the history and 
 symptoms present in all well-marked cases of hookworm 
 disease, these fail in a large number of cases that have not 
 obvious symptoms, either because of small number of 
 worms, or because of more or less immunity to the effects 
 of the worms. The most practical and satisfactory way 
 of arriving at a certain diagnosis is by examining the feces 
 for ova of the parasite. These are characteristic, easily 
 recognized, and, when worms are present in sufficient num- 
 bers and under such conditions as to cause symptoms, are so 
 easily found that the diagnosis becomes one of the most 
 simple procedures in the practice of medicine, provided one 
 is equipped with a microscope and proper knowledge and 
 experience, which can be easily acquired. The microscopic 
 examination of feces is of so much importance in diagnosis 
 that we believe a complete description of every detail is 
 warranted, including descriptions of the many things likely 
 to be mistaken for or confused with hookworm eggs. 
 
DIAGNOSIS, 157 
 
 Obtaining- Specimens for Examination. 
 
 The quantity of feces needed for a microscoiDic examina- 
 tion, even when the most comprehensive examination de- 
 scribed on ]jages 171 to 177 is to be made, need not exceed 
 two or three drams at most. Unless instructed on this point, 
 the patient will often bring or send large quantities or the 
 whole stool in fruit jars, large pickle jars, etc. Large ves- 
 sels of feces are much more exposed to accidents — such as 
 breaking or spilling, especially when the feces are liquid — 
 than smaller ones. More malodorous gases are given off 
 from a large amount of feces than from, say, one-twentieth 
 of this quantity. The opening ujd and handling of a small 
 quantity of feces in the laboratory or office is not nearly so 
 unpleasant as handling a much larger quantity. It is not 
 sufficient to tell the patient to bring only a small quantity. 
 This point must be impressed on him when requesting him 
 to bring the specimen. He should be told to bring only a 
 small quantity of the actual feces, and the physician should 
 make this more certain by furnishing him with a suitable 
 receptacle in which to bring or send the specimen, and when 
 it is given him to explain that he wants only a small quan- 
 tity in it and not to fill it full. Vaseline bottles, two-dram 
 quinine bottles, or other low form wide-mouth bottles serve 
 the purpose well. One who expects to have many specimens 
 of feces brought to him by his patients should provide him- 
 self with a proper supply of two-ounce wide-mouth bottles 
 with corks. They are also appropriate for sj^utum bottles. 
 These should never be used a second time. Wide-mouth 
 bottles also have a great advantage in permitting feces to 
 be put in and taken out of them. Moreover, when feces are 
 put in a narrow-mouth bottle, they usually lodge partly in 
 the neck, and, after the stopper is put in, gases form which 
 often blow out the cork and feces, soiling anything or any- 
 
158 HOOKWORM DISEASE. 
 
 body near by. When bottles are entirely filled with feces, 
 especially if liquid, the stopper is very likely to be blown 
 out when the package is unwrapped, if not before. If only 
 partly filled, this is not so likely to occur. 
 
 , Kind of Feces to be Examined. 
 
 Any kind of a stool will do for examination, but there are 
 reasons for preferring the formed feces instead of liquid 
 material. These reasons are that the preparation on the 
 microscope slide can be more satisfactorily made with 
 formed feces; that liquid feces are more odorous and 
 more likely to get out of the bottle accidentally; and 
 that eggs sometimes tend to settle to the bottom of 
 a liquid, and greater care is therefore necessary in mak- 
 ing the preparation on the slide; and that, if the speci- 
 men is very liquid, eggs are likely to precipitate and stick 
 to the bottom and sides of the bottle, and be missed when 
 only a few eggs are present, in spite of considerable agita- 
 tion. Pepper has called attention to the peculiarity pos- 
 sessed by hookworm eggs of sticking to the slide after they 
 have once settled in a slide preparation. One who wishes to 
 thoroughly familiarize himself with examination of stools 
 for hookworm eggs should try this for himself. Place on a 
 slide some sediment from centrifuging, described on page 
 173, containing hookworm eggs. Dip or invert the slide 
 in a beaker of water after allowing the material to settle 
 a few minutes. Now examine the slide under the micro- 
 scope, and the eggs will be found to have stuck to tile slide 
 even after considerable agitation, though everything else 
 came off. 
 
 Making- the Preparation for Microscopic Examination. 
 
 For the examination of feces the ordinary 3-inch slides 
 are too small for the most satisfactory manipulation. We 
 
DIAGNOSIS. 159 
 
 prefer 2x3-mc]i slides, or even larger. Photographic nega- 
 tive glasses 31/4x31/4, 3^/4x41^, or 4x5 are all very convenient, 
 and usually easy to get. The ordinary 1x3 slides, however, 
 serve the purpose well, especially if a mechanical stage is 
 used. 
 
 Put in the center of a slide one to three drops of water. 
 
 Fig-. 45. Diluted feces on slide, ready for microscopic examination. 
 
 and with a toothpick take up a quantity of feces about the 
 size of a match head. Stir this into the water until it is 
 about as cloudy as can be examined well with the micro- 
 scope, spreading out the diluted feces properly over the 
 slide at the same time. The diluted feces should not come 
 quite to the edge or ends of the slide at any point, as they 
 
160 HOOKWOEM DISEASE. 
 
 would then easily run off on the hands, microscope, etc. 
 The preparation should cover at least one-half the area of 
 the slide if the ordinary 1x3 slide is used. (Fig. 45.) The 
 thickness of the mixture must be learned by experience, but 
 it is desirable to have it dilute enough to allow a good light 
 to be had and a clear outline of the material on the slide. A 
 preparation that allows ordinary print to be read through 
 with the unaided eye is usually not too thick. It is not 
 necessary to continue stirring the feces off the pick after the 
 mixture becomes of the proper consistency. If properly 
 manipulated so as to rub off the feces gradually, it is easy 
 to stop at any point desired and to throw away any excess of 
 feces with the j)ick. Ordinary toothpicks are the best 
 things we have ever seen for making such preparations. 
 They have been used for a long time for this and similar 
 purposes by many laboratory workers. They should be of 
 good quality and have one thin flat end. The same pick 
 should never be used for examining another specimen on ac- 
 count of the possibility of carrying eggs from one to the 
 other. Matches or other such pieces of wood serve tlie pur- 
 pose also, but not so well. A convenient way to dispose of 
 the soiled picks is to burn the used end over a flame, or they 
 may be dropped into the bottle, which is then stoppered so 
 as to avoid contamination and infection. 
 
 Use of Cover Glasses Unnecessary. 
 
 It is unnecessary to use cover glasses in examining feces 
 for hookworm or most other parasite eggs. With the mag- 
 nification generally used they are absolutely unnecessary. 
 It is usually necessary to examine preparations larger than 
 the regular cover glasses and sometimes several of them. 
 If it is desired to study a specimen with high powers for 
 some special purpose, it is easy to place a cover glass over 
 the part to be examined, and press it down gently to thin it 
 
DIAGNOSIS. 161 
 
 out. Cover glasses are also necessary if a great deal of 
 time is to be spent in examining a given slide, to prevent the 
 preparation drying out so rapidly. 
 
 Examine Only Wet Preparations. 
 
 The preparation is to be examined wet. As soon as it 
 dries it is useless, and, if this happens before an examina- 
 tion is completed, more water is to be added, or another 
 preparation should be made. A properly made preparation 
 can be entirely gone over with the low power lens before it 
 dries out appreciably. If spread out too thin, it will dry 
 much more rapidly. Most of the solid particles, including 
 eggs, if present, settle on the surface of the slide soon 
 after it is prepared, and are then found about in the same 
 level or focus, so that the thicker the layer, provided it does 
 not prevent seeing through it, the more concentrated will be 
 the objects on the surface. 
 
 Magnification. 
 
 The low power of any of the commonly used microscopes 
 is to be employed. The 2/3 objective and 1-inch eyepiece, 
 or the 16-millimeter objective and corresponding eyepiece, 
 give the proper magnification of about 100 diameters. 
 Higher magnification is undesirable for general work be- 
 cause the field is correspondingly reduced, and therefore it 
 takes much longer to look over a preparation. 
 
 Time Required and Number of Slides to be Examined. 
 
 The time required to examine for eggs varies with the ex- 
 perience and speed of the examiner, the number of eggs 
 present, the thickness and size of the preparation, and 
 whether there are many particles resembling eggs, requir- 
 ing close observation to differentiate them. If many eggs 
 
162 HOOKWOEM DISEASE. 
 
 are present, the diagnosis may often be made on the first 
 field examined, but to stop after finding a few hookworm 
 eggs is not good practice. The examination should be con- 
 tinued to find, if present, eggs of other parasites which are 
 likely to ^e present in small numbers, and to get some idea 
 of the number. When less than ten female worms are pres- 
 ent, there may be an average of less than one egg to a slide. 
 It is estimated that one actively laying female produces 
 two thousand to three thousand eggs in twenty -four hours, 
 but many of the worms lay much fewer eggs and a few old 
 ones lay none. 
 
 We recently had each man of several groups of five medi- 
 cal students examine five or more slides of one hundred dif- 
 ferent specimens of feces, twenty-nine of which finally 
 showed mild hookworm infection. The remainder, seventy- 
 one, were negative. Several instances occurred in which 
 only one or two men of the group found one or two eggs in 
 a particular specimen. These men had been thoroughly in- 
 structed and practiced in the recognition of hookworm eggs, 
 and it is believed were not likely to overlook them. Eggs 
 were found in only twenty-three specimens from this exami- 
 nation of twenty-five slides of each. The negative speci- 
 mens were now examined after being carefully washed and 
 centrif uged, and six found to contain eggs. In this instance 
 examination of twenty-five slides failed to demonstrate eggs 
 in 20 percent of the cases in which they were present. 
 These were the ordinary 1x3 microscope slides, and the 
 specimens were from adults who had very few worms — not 
 enough to produce any recognizable symptoms, except in 
 one or two instances. Most of them had not been rein- 
 fected in many years, and their worms certainly were not 
 laying as prolifically as younger worms do. 
 
 Another group of ten men were first well drilled on the 
 diagnosis of worm eggs and then set to work to examine 
 
DIAGNOSIS. 163 
 
 oue hundred and thirty-six specimens of feces that showed 
 on final examination fifty-eight infected, as follows: six 
 hookworm, thirty-two trichocephalus, eight tenia nana, 
 twelve oxyuris. One to five slides were examined — an 
 average of two or three. Thirty-one, or 53 percent, of the 
 specimens containing eggs were diagnosed negative by this 
 examination. They were mild infections, and all these 
 worms other than hookworms lay comparatively few eggs, 
 as is well known. These figures show that examining two 
 or three, or even twenty-five, ordinary slide preparations 
 is not sufficient to discover eggs every time when very few 
 are present. It is necessary to examine at least six to ten 
 slides before a practical negative diagnosis can be made, 
 but, if one hundred or more worms are present, eggs can be 
 found in every slide, except under rare conditions. The 
 number of worms in many well-marked or severe cases is 
 from one thousand to four thousand, and eggs, often several, 
 can be found in almost every microscope field. We can look 
 over thoroughly an ordinary slide in two to four minutes. 
 We have seen comparative beginners become able, with a 
 few days of practice, to examine well one slide in six to ten 
 minutes. 
 
 Light. 
 
 The amount of light used should be that giving the best 
 detail to the small particles in the preparation. On an 
 ordinarily bright day, or with artificial light, the maximum 
 light available when using any standard microscope will be 
 entirely too strong, and must be reduced by partly closing 
 the iris diaphragm under the Abbe condenser. The light 
 is increased or decreased with this diaphragm after the re- 
 flector has been adjusted so as to reflect directly all the light 
 falling upon it. The light should be such as permits eggs, 
 when present, to be seen well in detail. The outline of the 
 
164 HOOKWOEM DISEASE. 
 
 yolk and shell should be distinct, and the clear albumen 
 space should be well shown. With too bright a light the 
 whole egg is blurred and indistinct. 
 
 Method of Going Over the Slide. 
 ■J 
 
 If a mechanical stage is used, it is a good plan to begin 
 at one side of a preparation and to move the slide systemat- 
 ically from end to end, moving back or forth the width of a 
 field every time the end is reached until the entire slide has 
 been gone over. With a large slide, or if no mechanical 
 stage is used, the slide should be moved in the same manner 
 with the fingers. With practice and with low power, this 
 can be readily done. 
 
 Description of Eggs. 
 
 The ova of uncinaria Americana are ellipsoid, fifty-four 
 to seventy-two microns long by thirty-six to forty microns 
 broad, in some cases partially segmented in utero. The 
 ova of ankylostoma duodenale are ellipsoid, fifty-six to 
 sixty-one microns by thirty-four to thirty-eight microns, 
 laid in segmentation. The two varieties have practically 
 the same general appearance, and can not be differentiated 
 except by careful measurement. Uncinaria Americana 
 eggs are said to be more pointed at the poles. (Looss.) 
 Eggs may be seen lying flat, or they may be on end, in 
 which case they appear round. There are all variations 
 between these extremes, in which they appear shorter than 
 normal, due to their being seen in an oblique position on 
 the slide. With experience a mental picture of the size is 
 formed, which is all the guide to size necessary. Different 
 individuals see the size of things under the microscope dif- 
 ferently. To our eye, with a 1-inch eyepiece and a 2/3-inch 
 objective, hookworm eggs seem to be three-eighths to one- 
 half inch long by about one-fourth less than this in diam- 
 
DIAGNOSIS. 165 
 
 eter. The outline of the chitinoiis shell is smooth and regu- 
 lar, and shows as a narrow band. The regularity in out- 
 line of the shell often serves to differentiate them from the 
 capsular membrane enveloping the chlorophyl of many dif- 
 ferent varieties of vegetable cells. The yolk is made up of 
 fine granular dark gray material and contains a central 
 lighter area. When seen sufficiently early, the yolk is of 
 the same shape as the egg shell, and usually situated about 
 the same distance from it on all sides. There is a distinct 
 clear albumen space between the shell and yolk from one- 
 eighth to one-fifteenth as wide as the diameter of the egg. 
 Most of the eggs begin to segment before the feces are dis- 
 charged, and therefore those found in fresh material con- 
 tain two, four, or eight, or more segments. (Figs. 11, 13.) 
 In older stools embryos may be seen inside of the egg shell, 
 nearly ready to come out and moving around slowly in their 
 shell, which they nearly fill. (Fig. 11.) For a complete 
 description of the embryos and larvas see the chapter on 
 zoology. 
 
 Number of Worms Indicated by Number of Eggs. 
 
 Leichtenstern has proposed to estimate the number of 
 worms present by the number of eggs found in the feces. 
 He divides the number of ova contained in one gram of 
 feces by the factor forty-seven. Grassi and Parona esti- 
 mate the number of eggs in one centigram of feces and cal- 
 culate the number of worms, assuming that one hundred 
 and fifty to one hundred and eighty eggs per centigram rep- 
 resent one thousand worms. 
 
 Ashford and King have called attention to the fact that 
 certain things may prevent the correct estimation of worms 
 by the eggs present. They well say that the worms cause 
 an increase of mucus at the site of their feeding ground, 
 and, as this mucus often comes off en masse and contains 
 
166 HOOKWORM DISEASE. 
 
 most of the eggs, the actual feces would contain relatively 
 few. They sa^^ eggs are more difficult to find in diarrheal 
 stools for some reason or other, and in this connection we 
 mention the fact that the quantity of feces passed by differ- 
 ent individuals varies greatly with the size and age, the 
 kind and amount of food eaten, the digestive ability of the 
 patient, and also with the water intake and elimination, in- 
 testinal bacterial flora, etc. Ashford and King saw cases of 
 heavy infection that at times had no ova in their feces, 
 especially soon after thymol had been given, but they also 
 had patients with many ova two days after full thymol 
 treatment. With us it has been a common experience to 
 have a patient's feces reported negative within a few days 
 after a course of thymol and on subsequent examination 
 eggs be found in large numbers. This is more likely to 
 occur, of course, when the examination is not thorough. In 
 one instance after a course of thymol the most exhaustive 
 examination revealed no eggs one and two weeks afterward. 
 The patient remained in the city, and therefore was not ex- 
 posed to reinfection. It was winter, during which infec- 
 tion does not usually occur. Six weeks after the thymol 
 ova were again found, and one hundred and nineteen male 
 and female worms were expelled as the result of another 
 course of thymol. Dieminger found that the number of 
 eggs was very much diminished when patients were drink- 
 ing hard. He examined twenty-one men on Monday and 
 found only four infected; on the following Friday he found 
 many ova in eleven who had shown none on Monday. In 
 another instance he found a man heavily infected on Sat- 
 urday, but on the following Monday he could find no ova 
 after repeated search. The reason he assigns is that these 
 men had been drinking to excess on Sunday. It is not im- 
 probable that the activity of egg production by hookworms 
 is influenced by season of the year. Salt herring or other 
 
DIAGNOSIS. 167 
 
 very salty food also has some effect. One of us (Bass) has 
 recently reported the examination of two hundred and 
 forty-seven female uncinaria Americana, 7 percent of which 
 contained no ova, and suggested the possibility of old age 
 being the cause. Dr. Stiles, in discussing this question at 
 the recent Hookworm Conference in Atlanta, 1910, said he 
 was not prepared to say whether the worms live long after 
 old age induces cessation of ovulation, but, reasoning from 
 analogy, he did not think this probable. Though animals 
 highest in the scale cease to ovulate at the end of about two- 
 thirds of their usual life, it is not probable that any lower 
 forms do this, at least to the same extent. We have recently 
 examined three hundred and ninety-seven female uncinaria 
 Americana from patients whose ages and histories indicate 
 that they have not been reinfected for several years, and 
 these showed 9 1/4 percent of barren worms, whereas three 
 hundred and twenty dog uncinaria from young dogs showed 
 only 1/3 percent without eggs. It is very doubtful, how- 
 ever, whether a patient may be infected with any consider- 
 able number of worms without a few eggs being present in 
 the feces and always demonstrable by thorough examina- 
 tion. However, we believe the possibility of only a very 
 few old worms being present is to be thought of in cases 
 with a history indicating previous existence of the disease 
 and persistence of symptoms. This may explain some of 
 the cases of persistence of eosinophilia and other symptoms, 
 though no eggs are present. If such cases occur, the only 
 way to clear up the diagnosis positively would be to give a 
 course of treatment and examine the feces thoroughly for 
 worms. 
 
 Differentiation of Uncinaria Eggs from Other Ova, Etc. 
 
 The eggs of uncinaria are easily differentiated from those 
 of other parasites, except possibly strongyloides. Stron- 
 
168 HOOKWORM DISEASE. 
 
 gyloides eggs have the shape and appearance of hookworm 
 eggs, and measure about seventy microns long by thirty-five 
 microns thick. The shell is clear, but yellow. They are 
 seldom seen, because they almost alwa3^s hatch while in the 
 intestine and sometimes before they are expelled from the 
 uterus, and when an egg is found there are also to be found 
 in the feces thousands of strongyloides larvse. These can 
 not be easily differentiated from uncinaria larvae, but, if it is 
 remembered that uncinaria larvas are not found in fresh 
 feces, little difficulty is experienced. If the stool is suf- 
 ficiently old (twenty-four hours or longer) for uncinaria 
 larvae to have hatched out, there will still be present in any 
 specimen of undiluted feces far more eggs than larvae — a 
 thing never seen with strongyloides. Strongyloides larvae 
 are differentiated from uncinaria larvae by the presence of 
 a larger double dilatation of the esophagus and by the de- 
 velopment of the filariform stage when the material is kept 
 for six or eight hours or longer. The primordium, which 
 later develops into the sexual organs, is seen at about the 
 middle of the body of each, but in strongyloides it is large 
 and oval, whereas in uncinaria it is small and round. They 
 develop long (four-tenths to seven-tenths of an inch), nar- 
 row, very active worms, with an esophagus almost one-half 
 their length. Hookworm larvae, on the other hand, become 
 encapsuled in four to five days. Double infection may 
 occur. Ascaris lumbricoides eggs are larger, fifty to sev- 
 enty microns long by forty to fifty microns thick, have a 
 thick, rough, albuminous, bile-stained coating of the shell, 
 are more oval, and have less albumen space. Tricho- 
 cephalus eggs are smaller, about fifty by twenty-three 
 microns, more oblong, and have a cap on each end, "lemon 
 shaped." Oxyuris eggs are smaller, fifty by twenty mi- 
 crons, more oblong, and have a relatively smaller nucleus. 
 One side is straight and the other curved, and one end is 
 
DIAGNOSIS. 169 
 
 smaller than the other. They are more refractile, giving 
 them a shining appearance, and slightly yellow. Most of 
 the eggs seen are empty shells from which the embryo has 
 already escaped. Tenia eggs are smaller, have a thick shell 
 consisting of an inner and an outer membrane, between 
 which there is a thick layer of albuminous material. In 
 tenia saginata, tenia solium, and tenia diplogonoporus 
 grandis this is distinctly striated, while the tenia nana has 
 only a few longitudinal bands running through this part 
 of the egg, starting from the poles. All have booklets 
 or the resemblance of booklets in their nuclei. Bothrio- 
 cephalus latus eggs measure about forty-five by sixty-eight 
 to seventy-one microns, and the nucleus entirely fills th^ 
 shell. They are brown, and a cap or lid can be seen at 
 one end. 
 
 The beginner often has difficulty in differentiating from 
 eggs various vegetable cells and sometimes other food 
 material, balls of bacteria, etc. After fixing a correct 
 mental picture of the size and shape of hookworm eggs by 
 studying known specimens, including the appearance of the 
 nucleus, and observing the rule that nothing is to be called 
 an egg that does not consist of a definite shell, yolk, and 
 clear space, little trouble is experienced. The beginner often 
 diagnoses vegetable cells as uncinaria eggs. Those foods 
 that are "mealy" when cooked — like beans, peas, potatoes, 
 etc. — or when raw — like apples, etc. — furnish the greatest 
 quantity of deceptive vegetable cells. Many a time we have 
 known cells diagnosed as hookworm eggs by those who had 
 seen eggs several times before, notwithstanding the fact 
 that there were often in the same fluid many other similar 
 cells not at all egg-shaped and several times larger or 
 smaller than the cells diagnosed. Vegetable cells are irreg- 
 ular in outline, shape, and size, while hookworm eggs are 
 regular in these particulars. While vegetable cells may be 
 
170 HOOKWORM DISEASE. 
 
 found strongly resembling hookworm eggs, there will be 
 found in the same specimen, and usually in the same field, 
 many cells, otherwise like the one in question, which vary 
 much in appearance from uncinaria eggs. The segments of 
 the yolk 9f hookworm eggs are made up of very fine granu- 
 lar matter, whereas the chlorophyl granules of vegetable 
 cells are much coarser. Finally, the space between the 
 yolk and shell of eggs varies much at different points, 
 whereas the outer membrane of vegetable cells dips in over 
 depressions in the nuclear material, and in fact makes a 
 covering of the same thickness over the irregular nuclear 
 mass. If in doubt as to the diagnosis of the eggs, they may 
 be hatched out in twenty-four to forty-eight hours and the 
 characteristic larvae looked for. To this end some feces 
 may be placed in a Petri dish, or other suitable container, 
 and a few folds of filter paper stuck down in it, with one 
 end extending above the material. This serves to dry 
 it out sufficiently, and, if the culture is kept in a warm, 
 shady place, hatching soon occurs; or the feces may be 
 mixed with one or more parts of charcoal or sterile sand, in 
 which the eggs hatch well. This should be moist, but not 
 covered with water, which interferes with hatching. The 
 larvae may be found in material from around the edges of 
 the paper or dish, but after a few days will crawl up on the 
 sides and cover of the dish, as shown by Claude A. Smith 
 in his excellent experimental work on this subject. He 
 noted little grayish smears, consisting of numerous larvae, 
 on the sides and cover of the culture dish. Larvae of im- 
 cinaria in stools are not found, except in rare instances, 
 until twenty-four hours or longer after evacuation. We 
 have often found them in feces, always associated with 
 large numbers of eggs, sent by mail — usually specimens 
 that had partly dried out. It must be remembered that 
 there is a large number of nematodes, to which uncinaria 
 
DIAGNOSIS. 171 
 
 belong, the rhabditiform larvie of wliicli can not be easily 
 differentiated from each other. 
 
 Special Methods for Greater Certainty in Finding the Eggs. 
 
 Pepper's method. — Pepper, as mentioned above, has 
 called attention to a peculiarity of hookworm eggs which 
 makes it possible to concentrate them considerably, or at 
 least to get rid of much of the fecal matter and thereby 
 render them more easily found. He notes that when mate- 
 rial containing eggs is allowed to settle on a slide, the slide 
 may be immersed in water and considerably agitated with- 
 out the eggs coming away, though the slide is inverted and 
 all the feces rinsed off. We have often confirmed his find- 
 ings. The best results are obtained if a part of the fecal 
 material is removed by use of the centrifuge before the 
 slide preparation is made. Otherwise the method is often 
 disappointing. 
 
 Kiilz recommends Telemann 's method of examining feces. 
 In this, equal parts of ether and pure hydrochloric acid are 
 shaken up with a bit of feces, filtered through gauze and 
 centrifugated. The fat rises to the top; in the middle layer 
 are the solution and detritus, and at the bottom insoluble 
 remains and eggs. We have found the method admirable 
 with some stools, but in others not enough solution occurs 
 to permit a concentrated layer of eggs to be thrown down. 
 
 Sedimenting the feces by diluting with ten or more times 
 the amount of water, and allowing the mixture to settle for 
 fifteen minutes or longer in a beaker, test tube, or conical 
 glass, assures greater success than examining the untreated 
 feces. The eggs, being larger and heavier than many of 
 the particles making up the fecal mass, settle faster and 
 are more numerous in the bottom of the container. Mate- 
 rial may now be taken from the lower layers and a slide 
 preparation made in the usual manner. By repeating the 
 
172 HUOKAVOim DISEASE. 
 
 sedimentation several times, still better results may be 
 obtained. Concentration of the eggs with the centrifuge 
 has been referred to by Looss, Claude A. Smith, Ashford, 
 King, and others. Simply centrifuging the diluted feces 
 does not^ however, give the best results. They are obtained 
 only when the most careful attention is paid to details 
 which we believe are of sufficient importance to warrant 
 thorough consideration here. One-third or more of the fecal 
 mass consists of bacteria which are relatively very small 
 compared with the size of eggs. They have, therefore, a 
 much greater surface per given weight than eggs. Most of 
 them have a lower specific gravity also. Much of the feces 
 consists of food particles ranging in size from that of bac- 
 teria up to coarse macroscopic particles. Most of these 
 food particles are irregular in outline and shape, making 
 their surface per given weight greater than that of the 
 round, oval eggs. The specific gravity of much of this 
 material is less than that of eggs, and some of it even heav- 
 ier. Feces also contain variable amounts of concretions — 
 ''fecal sand," vegetable cells, crystals, etc. — which are usu- 
 ally heavier than eggs. 
 
 Centrifuges. — These are of three kinds — hand, water, and 
 electric. The speed of a hand centrifuge varies according 
 to the rapidity of the operator, but fairly high speeds can 
 be obtained. They can be started and stopped quickly. 
 Water centrifuges do not, as a rule, get up high speed, and 
 they start and stop slowly. Good electric centrifuges run 
 at high speed, and start and stop quickly. The Purdy cen- 
 trifuge, made by Williams, Browne, and Earle, is the best 
 we know for this purpose, though some others are good. 
 Satisfactory work for practical purposes can be done with 
 a good hand machine that costs only about $8.00. 
 
 The feces should be diluted and well mixed with ten or 
 more times their bulk of water. This should be strained 
 
DIAGNOSIS. 173 
 
 through two or three layers of gauze in a funnel to remove 
 the coarse particles. The exact length of time necessary 
 to centrifuge, in order to throw most of the eggs suspended 
 in water to the bottom of the tube, should be determined by 
 experimenting with a known specimen that has already 
 been washed once or twice and contains many eggs. This 
 must be determined with the particular centrifuge used. 
 The Purdy centrifuge used by us, running at full speed, 
 throws eggs to the bottom in four seconds. "With a hand 
 centrifuge it takes considerably longer, depending on the 
 speed obtained. As the first diluted feces are much thicker 
 than the washed feces and eggs on which the working time 
 of the centrifuge has been determined, the eggs will go 
 down somewhat slower the first time. It is, therefore, a 
 good plan to centrifuge double time at first. If, for in- 
 stance, the working time of the centrifuge is four seconds, 
 the first centrifuging should be eight seconds. This throws 
 to the bottom most things heavier and larger than eggs — 
 like crystals, sand, large vegetable cells, etc. — and all eggs 
 present. There remain suspended in the supernatant fluid 
 nearly all bacteria and fine particles, and many coarse 
 particles lighter and more irregularly shaped than eggs. 
 If the centrifuge is run longer, many of these go down, 
 which is, of course, undesirable. Pour off this fluid, and 
 two-thirds, and often much more, of the feces are removed 
 by this washing. Eefill the tube to about three-fourths its 
 capacity, shake up thoroughly, and centrifuge again, run- 
 ning now only the working time of the centrifuge. It is 
 important not to centrifuge longer than the working time of 
 the centrifuge, as many fine and light particles would other~~- 
 wise be thrown down. Considerable material remains sus- 
 pended, and may be removed by pouring off the super- 
 natant fluid. Again the tube is filled, shaken, and centri- 
 fuged a proper length of time, and generally this will be 
 
174 HOOKWOEM DISEASE. 
 
 sufficient for jDractical purposes. A part or all the sedi- 
 ment is removed with a pipette, spread out on a slide, and 
 examined for eggs. It consists of crystals, sand, and heavy, 
 coarse food particles, and eggs if present. It is important 
 to remove the sediment x)roijerly. A clean pipette, with 
 the finger held over the end of it, is carried to the bottom 
 of the tube. Before removing the finger and allowing the 
 sediment to run in, it should be well broken loose from the 
 bottom of the tube by means of the pipette. Then the 
 finger is partially removed, and a part or all the sediment 
 allowed to run up into the pipette. Part or all this is 
 spread on a slide and examined as usual. A worker accus- 
 tomed to this procedure is able to wash, centrifuge several 
 times, and get the sediment of a specimen on a slide ready 
 for examination within four or five mmutes. The examina- 
 tion takes about the same time as is required to examine 
 an ordinary preparation of feces of the same size, but usu- 
 ally all the sediment may be placed on one slide, and one 
 slide is, therefore, all that it is necessary to examine. A 
 mechanical stage enables one more thoroughly to go over 
 the slide. A large amount of the sediment can be examined 
 if Pepper's technic is now used. After allowing the thick 
 smear to settle well, the slide is immersed in a beaker or 
 glass of water. Uncinaria eggs remain, but most other 
 things wash off. One serious objection to following this 
 technic is that, while looking for hookworm eggs, we also 
 want to find any other eggs present. No other eggs we 
 know of stick to the slide like hookworm eggs. This pro- 
 cedure cannot, therefore, be recommended for general work. 
 Great care must be exercised to clean the centrifuge tubes 
 before using them after they have had eggs in them. A 
 proper centrifuge tube brush is serviceable. 
 
 The method of centrifuging described above is all that is 
 necessary for ordinary practical purposes, and, if properly 
 
DIAGNOSIS. 
 
 175 
 
 done, permits the finding of eggs when less than half a 
 dozen laying females are present, and often when only one 
 is present. It is of additional service because it permits at 
 the same time diagnosis of infections with many other 
 worms by which much fewer eggs are laid, such as the 
 tenias, oxyuris, bothriocephalus, etc. Bass found that he 
 could still further concentrate the eggs by washing with 
 calcium chloride solution after washing with water. The 
 
 Fig. 46. Microscopic appearance of feces, sliowing poorly one egg in 
 center. 
 
 specific gravity of fresh hookworm eggs is near 1,100. This 
 usually increases as the specimen gets old. A solution of 
 calcium chloride having a specific gravity of 1,050 will sus- 
 pend considerable of the sediment, though the eggs still 
 readily go to the bottom. By washing with this solution 
 two or three times after washing with water, much material 
 not removed with the water can be removed. If still better 
 results are desired, the crystals and very heavy things can 
 
176 
 
 HOOKWORM DISEASE. 
 
 be removed by washing with a solution of calcium chloride 
 of 1,250 specific gravity, in which most of them go down, 
 but hookworm eggs float. After centrifuging, the super- 
 natant fluid containing the eggs is poured off and appropri- 
 ately diluted with water, and the eggs again thrown to the 
 bottom, from where they are easily taken up. This calcium 
 chloride washing is necessaryonlywhen very great accuracy 
 
 M 
 
 ^^^ 
 
 P9 
 
 M 
 
 ^^^ 
 
 P^^Ha'^a^^^^^B) 1 
 
 m 
 
 ^^^ 
 
 ^m 
 
 ^^^B^^^^k3 
 
 ^^^^^^ 
 
 ^^m 
 
 He^ 
 
 ^!^3K^Sl^fHil 
 
 i^i^H 
 
 Fig. 47. Preparation made by Bass' method from feces shown in Fig-. 46. 
 Appear about as large as they do with 1/6 objective and 2-inch eyepiece. 
 
 is desired, or when it is desired to collect eggs absolutely 
 free from fecal material for scientific purposes. Solutions 
 of calcium chloride of several different strengths should be 
 employed for this purpose, and much is also gained by keep- 
 ing the patient on a wholly digestible diet. Bass found that 
 with this technic he was able to recover 96 percent of one 
 thousand eggs placed in one ounce of feces, 94 percent of 
 one hundred eggri in the ^ame amount, and 60 percent of 
 ten eggs in one ounce. The value of the centrifuge is shown 
 
DIAGNOSIS. 177 
 
 by the work of Gage and Bass. They examined the feces of 
 315 university students. One to 25 slides were examined 
 in the ordinary way, and 104 cases were found infected with 
 some intestinal parasite, 79 of them being hookworms. The 
 specimens found negative by the ordinary technic were cen- 
 trifuged, either using water only or water and calcium 
 chloride solution, as described. By this method 38 ad- 
 ditional hookworm cases were found. Of the entire 104 
 cases of intestinal parasite infection 47 percent were found 
 by the usual technic, and 53 percent were missed until the 
 centrifuge technic was employed. It is to be emphasized 
 that most of this series of cases were mild cases of uncinari- 
 asis, or infection with other worms that lay fewer eggs than 
 uncinaria. Gage and Bass conclude after this extensive ex- 
 perience that, for all practical purposes, washing with water 
 alone is all that is necessary, and that the washing with 
 calcium chloride solution is unnecessary, except for special 
 purposes. 
 
 As to whether it is necessary to use the centrifuge in 
 every case, we would say that it is not in the ordinary diag- 
 nosis and treatment of hookworm disease, but that it is 
 necessary for the recognition of many cases of mild worm 
 infection. The time consumed, ten to fifteen minutes, is not 
 as great as that required to make a much less reliable ex- 
 amination by the ordinary technic, and the satisfaction de- 
 rived from being certain that no eggs are present is worth 
 the effort. 
 
 Diagnosis by Examining Stools for Worms after Treatment. 
 
 Either thymol or beta-naphtol may be given for this pur- 
 pose, and, though usually recommended in smaller doses for 
 diagnosis than for treatment, we believe that, unless special 
 contraindications exist, the full regulation dose should be 
 given, preceded and followed by the same purgation and 
 
178 HOOKWOEM DISEASE. 
 
 starvation as if a well-marked case was being treated. All 
 feces passed during the first twelve to twenty-four hours 
 after the last purge should be examined by washing, as de- 
 scribed by Dr. Stiles. They are stirred in a bucket or other 
 suitable vessel with water, after which the mixture is al- 
 lowed to settle a minute or two. The supernatant fluid is 
 poured off and the sediment rewashed several times. After 
 washing thoroughly, the residue is placed in a flat dish or 
 vessel with water in it, and the worms searched for. A 
 glass dish placed over a black surface, or one painted black, 
 makes the identification of the worms easier. The worms 
 may be collected with a pair of tweezers. They are about 
 the thickness of a common brass pin, from three-eighths of 
 an inch (shortest males) to five-eighths of an inch (longest 
 females) in length, and are white or gray in color, according 
 to the amount of food and eggs they contain. A complete 
 description of the worms is given in the chapter on zoology. 
 It should be said here that the worms are not likely to be 
 found in the stools, except after treatment. The history 
 often related by people that they saw hookworms in their 
 stools usually means that they have mistaken some other 
 worm or food particles for hookworms. In fact, the worms 
 are often not found even when many are present, unless 
 they are properly looked for and with great care. 
 
 Blotting Paper Test. 
 
 Stiles has found that in a large proportion of medium or 
 severe cases of uncinariasis this test is positive. It is made 
 by placing on a piece of white blotting paper, or other soft 
 white paper, some fresh feces. In about fifteen minutes 
 these are removed, and when the test is positive the paper 
 will show a red or reddish brown blot where the feces had 
 been. Though of service in some cases, the test can not be 
 recommended for general use, because of the many other 
 
DIAGNOSIS. 179 
 
 sources of positive tests besides hookworm disease, such as 
 other hemorrhages, vegetable coloring matter, etc. We 
 have found it positive, however, in several severe cases of 
 uncinariasis. 
 
 The Eosinophile Count in Diagnosis. 
 
 The importance of the eosinophile leucocyte count in the 
 diagnosis of hookworm disease has been emphasized by 
 Boycott and Haldane, and under certain conditions may be 
 of value. They found of one hundred and forty-eight men 
 infected with ankylostoma duodenalis 94 percent had over 8 
 percent of eosinophiles, and only 3 1/2 percent had less than 
 5 percent of eosinophiles. In eight hundred noninfected 
 miners there were only seven cases of eosinophilia. The 
 feces of one of those were not examined. Two showed 
 ascaris eggs, and the other four showed trichocephalus dis- 
 par eggs. They especially recommend the eosinophile 
 count because of the rapidity with which it can be made. 
 They examined one hundred and eighty-three films in four 
 days. 
 
 They themselves point out that the method is most useful 
 only in regions where other causes of eosinophilia are rare. 
 They say "this method could not be employed with success, 
 for example, with an ordinary Swiss population, where 
 ascaris is a frequent cause of a high grade of eosinophilia; 
 still less in the tropics, where natives have more than one 
 cause of eosinophilia in their persons besides ankylostoma. 
 No suggestion has ever been made by us, however, that it 
 should be used under these circumstances, nor has it been 
 proposed that the examination of blood films should replace 
 the search for eggs in the feces in persons in whom a prima- 
 facie case for the presence of ankylostomiasis has been 
 made out. The ultimate diagnosis, which is preliminary 
 to treatment, must rest on the examination of the feces. A 
 
180 HOOKWOEM DISEASE. 
 
 IDreliminary examination of the blood will, however, save a 
 great deal of trouble in cases, as in English miners, where 
 other causes of eosinophilia are practically absent." 
 
 In six hundred and ninety-three cases of hookworm in- 
 fection in ^various degrees of which we have record of the 
 blood examination the eosinoijhile count was 5 percent or 
 over in two hundred and twelve and below 5 percent in four 
 hundred and eighty-one. The highest count was 34 per- 
 cent and the lowest 1 5 percent. The average for the 
 entire' number was 4 1. 8 percent. The average for two 
 hundred selected lowest count cases was 2 1/3 percent. It 
 should be stated that the majority of these cases were mild 
 infections, and indeed many of them so mild as to require 
 the use of the centrifuge before ova were found. In four 
 hundred and four well people, whose blood and feces were 
 examined and no uncinaria or other eggs found, the eosino- 
 philes averaged 2 7/10 percent. The highest was 17 per- 
 cent and the lowest none in a five hundred cell count. 
 Above 5 percent was recorded in thirty-four instances. 
 Many cases of severe uncinariasis have not more than the 
 normal count, as pointed out l)y Ashford and King, and this 
 is true in almost all cases shortly before death. It is cer- 
 tain, however, that most moderate or severe cases of hook- 
 worm infection have counts above the normal. From the 
 above and our own exjDerience we would conclude that the 
 chief value of the eosinophile count in the diagnosis of 
 hookworm disease lies in the suggestion a high count makes 
 to examine the feces when the disease has not otherwise 
 been suspected. Eosinophilia is present in so many hook- 
 worm and other worm infections that we lielieve the feces 
 should always be examined when high counts are obtained. 
 
 In this connection it may be well to call attention to the 
 fact that a count of one hundred cells does not give a re- 
 liable estimate of the percentage of eosinophiles or any 
 
DIAGNOSIS. 181 
 
 other cells found in small numbers. It is necessary to count 
 at least three hundred cells, and preferably five hundred. 
 Much speed can be gained b}^ taking only the total leu- 
 cocytes and the eosiuophiles. Counting by twos, threes, 
 or fives, instead of by ones, also saves time. For speed the 
 thickest part of a spread, where the cells can be differen- 
 tiated, is best. 
 
CHAPTER VIII. 
 
 PROGNOSIS. 
 
 The prognosis of hookworm infection varies within wide 
 extremes, depending on several factors, such as number of 
 worms, age and constitution of the patient, possibility of 
 getting proper food, and especially of receiving proper and 
 timely treatment. 
 
 If the worms are few and the individual well nourished, 
 hookworm disease does not always develop. The subject 
 remains a carrier. Though not ill subjectively, he is, how- 
 ever, in a pathologic condition, and often shows, on careful 
 examination, not only ova of the parasites in the stools, but 
 also slight loss of weight in proportion to his age, slight 
 lowering of the blood-coloring matter and red blood cor- 
 puscles, and eosinophilia. We believe these slight abnor- 
 malities are not without importance. If the subject is able 
 to eat, digest, and assimilate enough proper food, and to live 
 comfortably, he may be able to keep abreast of his contem- 
 poraries in school and college, and to hold his own at work, 
 or in business or a profession. By six or seven years after 
 his last infection, in most cases, he is free from parasites, 
 these having died of old age. Under favorable circum- 
 stances the subject now recovers completely. In some cases, 
 however, we suspect that the drain, though slight, caused 
 by the parasites will have damaged the host, and that neu- 
 rasthenia, or vascular or cardiac disease, may come on by 
 reason of the excessive calls on the energy of the latter. 
 For this reason, as well as for prophylactic purposes, all 
 hookworm carriers should be sought out and treated. If 
 
 182 
 
PROGNOSIS. 
 
 183 
 
 they are exposed to reinfection, the risk of permanent, even 
 though slight, damage is greater. 
 
 It is doubtful whether true immunity occurs in Caucas- 
 ians. Mild cases may go on for years, the worms gradually 
 undergoing senile changes, and therefore less potent for ill. 
 
 In moderate infections, among poor people, a lowering of 
 physical and mental and moral strength occurs. School 
 children so affected may not be able to accomplish more 
 than 60 percent of required work. 
 
 The worst cases are those in which there is a heavy infec- 
 tion, with from one to many thousand worms. Even in 
 well-to-do subjects these become severely affected, but 
 among the underfed or the overworked the results are most 
 serious. Either the patient becomes rapidly anemic, with 
 digestive disorders, sometimes severe diarrhea with hemor- 
 rhages, anasarca, and extreme debility, or the conditions 
 may be more chronic. Indolence and weakness lead to care- 
 less habits. Reinfection occurs from time to time. Often 
 a whole family becomes affected more or less seriously. 
 The wage earners lose part, or later all, of their income, the 
 food supply becomes more scanty, and a vicious circle of 
 poverty, weakness, and disease is established. Often doc- 
 tors are far away, or even not accessible at all, and a whole 
 family may be exterminated before the youngest children 
 are half grown. Formerly these cases were supposed to die 
 of pernicious malaria, of nephritis, and in some countries of 
 beriberi. We strongly suspect, with many other southern 
 physicians, that many cases in negroes, ending fatally and 
 supposed to be tuberculosis, are undiagnosed cases of hook- 
 worm disease. The difficulty of getting a clear history in 
 negroes, the rarity of physical diagnosis and sputum exami- 
 nation, and the similarity of the late symptoms in the dis- 
 ease make the confusion a very natural one. 
 
184 hookworjm disease. 
 
 Mortality. 
 
 The mortality of hookworm disease in America can not 
 yet be accnrately stated. The disease has not been known 
 long enough, and the diagnosis is not attempted often 
 enough, \o furnish data of value. In Porto Rico Ashford 
 and King estimated the death rate before systematic treat- 
 ment was begun at 30 percent, which was probably not too 
 high. In Egypt, among cases treated, Sandwith thinks 
 89.5 percent are cured or greatly relieved, 2.5 are un- 
 relieved, and 8 percent die. One-third of the latter are first 
 seen moribund, another third die of various complicating 
 diseases, and the remaining third of hookworm disease. 
 
 In the prognosis of a given case the most useful guides 
 are the general condition and the condition of the most im- 
 portant organs, the probable number of worms as shown 
 by the fecal examination, and the possibility of proper treat- 
 ment, which often depends upon the financial condition of 
 the patient. ' ' The destruction of the poor is their poverty" 
 applies with particular force in hookworm countries. 
 
 Of other points, eosinophilia has some value. In severe 
 cases, if present, it is usually a sign that the disease has not 
 gone on to complete exhaustion of the blood-forming organs. 
 In mild cases it often indicates periods of relative well- 
 being. Prof. Fiilleborn, of Hamburg, who had an experi- 
 mental infection, told us his eosinophiles were always 
 higher when he was feeling best. 
 
 The Porto Rico Commission, in 1904, wrote (page 84) : 
 
 ''The chief interest centered around the eosinophiles. 
 There is no doubt that the following conclusions may be 
 drawn with safety (conclusions which, by the way, were 
 suggested in the report of the Ponce cases in 1903) : 
 
 "1. Very severe chronic cases, with poor resisting power 
 and exhausted blood-making organs, have little or no 
 
PROGNOSIS. 185 
 
 eosinopliilia. Leiclitenstern's remarkable case of 72 per- 
 cent eosinophiles just before death does not negative 
 this view. We had a case which died in coma, possibly due 
 to cerebral effusion. This child was admitted with 6.4 per- 
 cent eosinophiles and died with 20.8 percent. 
 
 "2. A rise in eosinophiles is of good prognostic import. 
 Especially is this true of those who, admitted to treatment 
 with conditions described under 1, begin to show higher 
 and higher eosinophile counts. There are such cases, not 
 explicable to us, where, in spite of a lack of rise in these 
 cells, improvement does take place. It may be rather rajoid, 
 but is generally very slow. 
 
 "3. If very severe cases, presenting little or no eosino- 
 pliilia, [have a] fall in their eosinophile count, the prognosis 
 is not generally good. 
 
 "In general, good resistance to the toxin of uncinaria is 
 expressed by eosinopliilia. Our special cases, being nearly 
 all severe, gave an average of 10.8 percent eosinophiles be- 
 fore any treatment was begun, and the ultimate percentage 
 of these cells, after all treatment had been concluded, was 
 13.2. As forty-two of the sixty-one were completely cured 
 at that time, and fifteen were nearly so, it is clearly seen 
 that the number of uncinarise, per se has nothing to do with 
 eosinopliilia directly. As to the oft cited remark that eosino- 
 phil ia and Charcot-Leyden crystals increase and fall to- 
 gether, there are cases which fail to show such relation. 
 
 "The eosinophiles behave in a most extraordinary way 
 in the course of cure. There seems to be a general rise to a 
 certain percentage, varying according to the individual, 
 after which a fall to normal takes place. This fall to 
 normal may occur before the patient reaches a normal 
 hemoglobin percentage, or may be delayed until some time 
 after cure. In this course of rise and fall, great undula- 
 tions may take place in the curve, which as yet seem to be 
 difficult to explain. 
 
186 HOOKWORM DISEASE. 
 
 ' ' Some very pertinent questions arise in consideration of 
 the question of eosinophilia: 
 
 *'l. Is it an evidence of blood regeneration, of increased 
 activity of blood-making organs? 
 
 "2. \s it that eosinophiles are directly concerned in the 
 defense of the organism against the toxin? 
 
 "There are many other theories concerning eosinophilia 
 in general — for instance, that of Weiss, who, Ewing says, 
 maintains 'that local eosinophilia tends to occur where 
 there is extensive extravasation of blood, the derivatives of 
 hemoglobin being absorbed by the polynnclear cells and 
 deposited in the form of eosinophile granules.' " 
 
 Among other elements in prognosis, pregnancy is an un- 
 favorable one. Abortion is likely to occur, and it as well 
 as birth at term may be fatal in anemic patients. Lacta- 
 tion is imperfect in hookworm patients, but promptly im- 
 proves under thymol treatment. The offspring of un- 
 treated hookworm patients are likely to be poorly devel- 
 oped and marantic. 
 
 While the most severe cases are seen in early life, the 
 disease is sometimes severe in cases that develop after 60. 
 All complications that contraindicate treatment render the 
 prognosis worse. 
 
 The effect of hookworm disease on duration of life is very 
 important. Old people in the rural districts of hookworm 
 countries seem less numerous than they are in cities, with 
 their greater exposure to numerous adverse conditions. 
 The Porto Rico Commission confirms this by stating that in 
 Porto Rico, though there are more children in proportion 
 to adults than in any other state, except South Carolina, 
 those over 60 years are forty to the thousand, as compared 
 with sixty-two to the thousand in the United States in 
 general. 
 
PROGNOSIS. 187 
 
 Intercurrent Diseases and Complications. 
 
 Like all conditions with anemia, hookworm disease is 
 likely to be associated with many other diseases. Some of 
 them are assisted by the anemia, and some are due to the in- 
 testinal derangements and the perversions of appetite. The 
 following are especially frequent: gastritis, dilatation of 
 the stomach, enterocolitis, amebic and bacillary dysentery, 
 edema of the lungs, neurasthenia, and nephritis. The latter 
 is very common in advanced cases. Syphilis and tubercu- 
 losis are not especially frequent, but are likely to be severe, 
 in hookworm subjects. Rheumatic pains are not uncom- 
 mon. Ashford and King recovered from the blood of such 
 cases a bacillus, which, however, they also found in other 
 diseases. Among other diseases frequently encountered in 
 histories of hookworm subjects are: tonsilitis, laryngitis, 
 pneumonia, paresis, hemiplegia, jaundice, ulcer of the 
 stomach, conjunctivitis and trachoma, renal colic, pellagra, 
 and elephantiasis. The last two named occur in endemic 
 areas, and the relation is only an assisting one. 
 
 As regards pneumonia, Gregorson reports some interest- 
 ing facts from Assam, where the tea-gardeners were for- 
 merly very severely affected with hookworm. Pneumonia 
 was also very frequent, but, as the hookworm disease be- 
 came less frequent under sanitation and treatment, there 
 was a notable fall in the incidence of pneumonia. The fre- 
 quency and severity of pneumonia in the southern states of 
 America have often been noted, and no good explanation 
 for it has been advanced. It can not be doubted that the 
 effects of hookworm infection lower the resi^stance, so that 
 depressing diseases of all kinds are more difficult to with- 
 stand. Moreover, the hookworm anemia lowers the amount 
 of oxygen-carrying blood, while lack of oxygen in pneu- 
 monia increases the need. 
 
188 HOOKWORM DISEASE. 
 
 Other Parasites. 
 
 It is to be expected that hookworm subjects slioiild often 
 liarbor otlier intestinal parasites as well as others, as they 
 usuallj^ live where parasites of all kinds are frequent. 
 Many of the other entozoa, though not all, are expelled 
 with hookworms after treatment. The following may be 
 named: ascaris lumbricoides and ascaris caninum; bil- 
 harzia, trichinella, strongyloides, balantidium, oxyuris, dip- 
 logonoporus grandis, amebse, fasciola hepatica, tenia sagi- 
 nata and tenia solium, aud filaria. 
 
 Among the most frequent sequels in severe cases are: dis- 
 eases of the heart, liver, and kidneys, endocarditis and arte- 
 riosclerosis, severe anemia, intestinal indigestion due to the 
 destruction of the mucous membrane by bites and infection, 
 and ulceration of the intestine. 
 
 Among rare results are perforation and stricture of the 
 gut. . , 
 
 It should be clearly understood that the prognosis in 
 hookworm disease is favorable in proportion to the prompt- 
 ness and the completeness of treatment. 
 
 In rare cases the condition is such that treatment can not 
 be borne, or the patient is too ill to recover even if the 
 worms are removed. 
 
CHAPTER IX. 
 
 PROPHYLAXIS. 
 
 "In the imiversal treatment of persons affected lies the 
 secret of successful opposition to uncinariasis." (Porto 
 Rico Commission.) 
 
 Hookworm disease is theoretically one of the easiest to 
 prevent. Its cause is known — unlike the causes of the 
 eruptive fevers, that still remain as tests of hygienic ef- 
 ficiency. All the vital characteristics of the parasite are 
 understood; it has no secondary host, like the tapeworms, 
 that spend part of their cycle in animals widely used as 
 food; it is not easily taken with drinking water or milk, like 
 the germ of typhoid fever; it is not carried, to any serious 
 extent at least, by flies or other insects, nor by the wind. 
 In a word, it does not come to man — man goes to it. 
 
 Practically it is one of the most difficult diseases to pre- 
 vent or eradicate on account of its wide extent, its intensity 
 in favorable localities, the enormous reproductive power 
 of the adult worm, the rapid development of the ova to the 
 infecting stage, and the commonest method, until recently 
 unsuspected, of infection. The very fact that the skin in- 
 fection has not been known longer may be the main reason 
 why the prophylaxis in the past has been so difficult. Wider 
 recognition of it may bring about a greater change. An- 
 other cause of difficulty in prevention depends upon the fact 
 that the sources of infection, their number, and danger re- 
 sult directly from careless or filthy habits. These, too, seem 
 almost ineradicable, but may be much more amenable to 
 education than they now appear. 
 
 The magnitude of the task of prevention appears from the 
 
 189 
 
190 HOOKWORM DISEASE. 
 
 statistics given in Chapter II. In hookworm localities 
 practically all children and many adults have the disease, 
 reinfection keeping it up much longer than the usual life- 
 time of each worm. Probably most rural negroes also are 
 affected in all parts of the world, but often do not show 
 symptoms. So the two classes of the population most re- 
 gardless of cleanliness can do most harm by their lack of 
 that virtue. 
 
 The problem of prophylaxis involves the following essen- 
 tial elements: 
 
 1. Stopping the danger of infection by exterminating the 
 mature worms in the bodies of human beings in order to 
 check the supply of eggs at the source. 
 
 2. Preventing the growth and existence of larvae in the 
 places where they develop. 
 
 3. Preventing infection by larvae that have developed, 
 notwithstanding the efforts mentioned under 1 and 2. 
 
 1. Extermination of the mature worms. — The first need 
 for the prevention of hookworm disease is to stop it in those 
 already affected — hookworm patients. This is a task that 
 will naturally fall upon the physician. When the disease 
 was unrecognized, cure was out of the question. Now that 
 the condition is so clearly realized that the symptoms are 
 often recognized even by laymen, and the microscopic diag- 
 nosis is easy to make, we can expect a distinct advance in 
 the successful treatment of these important cases as soon 
 as the people appreciate the danger now existing. Accu- 
 rate recognition of the sick, careful treatment, controlled by 
 examination of the feces, and repeated until perfect, will 
 lessen the supply of ova to a great extent. 
 
 But not altogether. There remains the great and im- 
 portant class of hookworm carriers — of people either with 
 no symptoms, or with symptoms so mild as to go unnoticed, 
 but with from a few to a couple of hundred worms, most of 
 
PROPHYLAXIS. 191 
 
 which will live for several years, laying eggs in large num- 
 bers all the time, and, in hookworm localities, keeping rein- 
 fected for longer periods. These people are all the more 
 dangerous because they are not supposed to be sick, just 
 as a child with mild scarlet fever or diphtheria is more 
 likely seriously to infect a whole school or community than 
 one with a severe case that will be promptly isolated. The 
 hookworm carriers require methods of hygienic treatment 
 not necessary for cases of illness of obvious kinds. As they 
 are not indisposed, they will not consult physicians; but, as 
 they are menaces to the health of the community, it is evi- 
 dently the duty and within the power of the health authori- 
 ties to search them out and deal with them as if they were 
 sick, and to see they become harmless. This not only in- 
 volves a new exercise of the police power already possessed 
 by boards of health, which seem arbitrary to those who have 
 barbarous ideas of personal liberty, but 'is a task beyond 
 the physical ability of the usual health administration as 
 now constituted. Hookworm eradication requires an ade- 
 quate sanitary organization, which would bring many bene- 
 fits besides checking hookworm infection. 
 
 It would be necessary to make periodic examinations of 
 all persons living in localities and under conditions favor- 
 able to the existence of hookworm larvae, and to keep 
 records of all of these; to examine all newcomers, to see that 
 treatment is carried out to a successful degree, and that 
 patients or carriers once cured do not become reinfected, or, 
 if they do, to treat them again. The same authorities 
 should organize education in regard to hookworm disease. 
 
 In localities where the population is known to the health 
 officers — as in camps, mines, tunnel or canal workings — the 
 inspection and treatment of newcomers could be easily ac- 
 complished. In mills and factories, employers would find it 
 to their advantage to have the hands periodically examined 
 
192 HOOKWOEM DISEASE. 
 
 aucl treated. A gain of 20 to 40 percent of hemoglobin, with 
 a corresponding gain of energy, would result. In towns, 
 villages, or country districts methods of surveillance that 
 have not as yet been applied in America would be neces- 
 sary. As regards patients, carriers, and suspects, there 
 should always be close and cordial co-operation between 
 practicing physicians and health authorities. 
 
 The value of accurate and careful methods under natural 
 disadvantages has been shown in many places within the 
 last few years, not only in the Westphalian, Belgian, and 
 French coal mines, but especially in the island of Porto 
 Rico, where the work of the ' ' Anemia Commission, ' ' organ- 
 ized by Ashford and King, has furnished a model of efficient 
 and economic administration. 
 
 2. Prevention of soil infection. — The next essential is the 
 prevention of soil infection. In all countries about the 
 dwelling houses, and in all mines, tunnels, or similar works 
 where men handle earth, soil pollution from lack of care 
 in the disposal of feces is the rule. If people with hook- 
 worms are present, the soil becomes infected, and, if the soil 
 and climatic conditions are favorable, the larvge develop. 
 The Porto Rico Commission (1904) expresses the matter 
 clearly: 
 
 ''Uncinariasis is pre-eminently a filth disease. The only 
 means of infecting the soil is by evacuation of the bowels 
 where the ova in the feces will later develop. If latrines 
 were generally used, uncinariasis would forever disappear. 
 . . . [There is] absolute disregard for sanitation in this 
 respect in the country districts. Practically all our Utuado 
 cases stated that they deposited their feces in the open 
 country, and had no latrine, nor even a hole in the 
 ground, for this purpose. Our special cases there are fair 
 examples of the average — of sixty-one persons, fifty-five 
 
PKOPHYLAXIS. 193 
 
 had no latrine. Six generally used them, but of these four 
 lived in town. In Bayamon a much larger percentage were 
 more comfortably situated in life ; three hundred and forty- 
 two were questioned on this particular, and fifty-three 
 stated they used latrines; the others, two hundred and 
 eighty-nine, never used one. Thus the average individual 
 living in the country, barefooted and devoted to agricul- 
 tural pursuits, from time to time acquires more and more 
 uncinariasis from infections sown by himself and his neigh- 
 bors. There is a constant inflow. The time naturally comes 
 when the parasites in his intestines die of old age, or some 
 accident which cuts their existence." 
 
 We do not know to what extent absence of latrines exists 
 in the hookworm area of the United States, but our own 
 observations lead us to agree with Stiles when he says 
 (1903): 
 
 "As we go into the country and visit the farms we not 
 infrequently find a condition, in respect to the disposal of 
 fecal discharges, which almost beggars description. Tak- 
 ing the rural districts visited during my recent trips as 
 example, it is not an exaggeration to say that, with the ex- 
 ception of the planters' premises, not over half of the coun- 
 try houses or huts of the sand region have any privy at all; 
 if there is one present, it is rarely properly cared for. Fur- 
 thermore, it is the exception rather than the rule that it is 
 used." 
 
 This and the resistance of the larvae, along with favorable 
 conditions of temperature and moisture, explain the danger 
 of the disease. The larvae are scattered by rains, all traces 
 of the feces become lost, but the porous moist earth, often 
 kept moist and protected from the sun by decaying leaves, 
 
194 HOOKWORM DISEASE. 
 
 becomes permeated with the larvae in the encysted and in- 
 fectious stage. Mines in the United States, for the most 
 part, do not present favorable temperature conditions, 
 though there is room for further observations in regard to 
 the actual freedom of our miners from infection. The coun- 
 try is the place where practically all our American infec- 
 tions take place, and the great majority of infections occur 
 near the home — in the "yard," garden, or barnyard. The 
 barnyard is especially dangerous for many reasons. The 
 ground conditions are often ideal for the development and 
 existence of larvae. Chickens, ducks, geese, and hogs scat- 
 ter the eggs and larvsB in all directions. Actual feces would 
 be avoided by people, but the invisible larvae can not be. 
 
 The greater use of water closets or privies in towns and 
 the universal wearing of shoes explain why hookworm dis- 
 ease is rarer in cities than in the country, and why the 
 anemic countryman gradually improves after he goes to the 
 city, and his hookworms die off and are not kept up by re- 
 infection. Similar differences exist in general between the 
 farm and the cotton mill, so that the anemic, poorly nour- 
 ished country girl, after working for some months in the 
 mill, shows such a contrast with her former self as one 
 might expect under ideal conditions of country life if the 
 conditions were reversed and she went anemic from the mill 
 to the country. Similar improvement gradually follows 
 when country children go to boarding schools. 
 
 For the prevention of soil infection, the use of some kind 
 of sanitary latrine is essential. It must be easily accessible 
 from the house or workplace, so that neither indolence nor 
 feebleness will lead to the use of less secure localities. It 
 must be kept clean in all parts. It nmst be inaccessible to 
 animals, and must be screened to prevent flies and other in- 
 sects from transporting material from it — a precaution even 
 more vnluable for the prevention of typhoid fever. 
 
PROPHYLAXIS. 195 
 
 The construction may vary with the local conditions, es- 
 pecially as regards water supply, sewerage, and soil. When 
 there is a proper sewerage system, water-closets are best. 
 The ova can not develop in the sewage, or, if they do, will 
 be swept away; and if the final disposal of the sewage is 
 what it should be, no harm can follow. 
 
 When the nature of the ground permits, and there is no 
 danger of contaminating wells, deep cesspools are very ef- 
 ficient. These can be built as septic tanks, with arrange- 
 ments for flushing when desired, and for using the waste as 
 fertilizer, as devised by Mr. Philbrick, quoted in Parkes' 
 Manual of Hygiene. 
 
 Shallow pits or boxes are objectionable for many reasons, 
 but sometimes offer the only method available. In such 
 cases they should be treated every day with slacked lime, in 
 order to disinfect not only against possible hookworm 
 larvae, but also against the germs of typhoid fever. Leak- 
 ing of the contents must be prevented, especially washing 
 away from heavy rains, which could scatter the larvae. 
 
 A better arrangement is the movable pail system. In 
 this, water-tight galvanized iron pails or buckets are kept 
 under the seat of the closet. When a pail is put in position, 
 as after each cleaning, a thin layer of sand is put in the bot- 
 tom. Enough crude carbolic acid, diluted with twenty 
 times its bulk of water, may be poured into the pail. The 
 pail must be easily accessible either from the front or back. 
 As often as necessary it is taken out, the contents buried in 
 a i^it or trench, covered over with earth and quicklime, the 
 pail cleaned and disinfected, and replaced in position. 
 
 The contents of the pail may also be treated in a septic 
 tank, in which case no disinfectant, such as carbolic acid, 
 can be used. They should not be put where they can be 
 washed away by rain, nor used as fertilizer, unless after re- 
 maining at least three weeks in the septic tank. They must 
 
196 
 
 HOOKWORM DISEASE. 
 
 not be put on a manure pile, nor left where animals can 
 scratch over them. 
 
 These arrangements, however, do not suffice for the needs 
 of country life, as privies near or in houses can not be util- 
 
 Fig. 48. A sanitary privy, designed to prevent the spread of disease. 
 If a privy of this type were built on every farm and in every yard in vil- 
 lages, and if this privy were used by all persons, typhoid fever, hookworm 
 disease, and various other maladies would almost or entirely disappear. 
 (After Stiles.) 
 
 ized at all times by all people. It is necessary, therefore, on 
 plantations, truck gardens, fruit or turpentine orchards, or 
 at charcoal furnaces, and similar places to have some sani- 
 tary closet near the workmen. This may be a properly con- 
 
PKOPHYLAXIS. 
 
 197 
 
 structed privy, if the conditions warrant, or a portable 
 privy, or a shelter of some kind over a pit or trench. In 
 such cases it should be a rule that dry earth and, if pos- 
 sible, quicklime should be used with a shovel to cover the 
 
 Fig-. 49. A sanitary privy very similar to that shown in Fig. 48. (After 
 Stiles.) 
 
 feces, and here, too, the danger of flooding in rainstorms 
 must be avoided. 
 
 It is interesting to see that Moses, who gained his hy- 
 gienic ideas in Egypt, the classic home of hookworm dis- 
 
198 HOOKWORM DISEASE. 
 
 ease, ordered for liis people a preeantion that might still 
 be acted upon with advantage by all who live on the land in 
 hookworm countries. Whether it was as necessary in the 
 Sinaitic desert as in the Nile valley may be questioned, but 
 there can be no doubt of its usefulness in many populous 
 cultivated lands. Moses said (Deuteronomy xxiii, 12, 13) : 
 ''Thou shalt have a place also without the camp, whither 
 thou shalt go forth abroad; and thou shalt have a paddle 
 (or shovel, in Porto Eico the machete or cutlass, carried by 
 every laborer, is recommended) among thy weapons; and it 
 shall be when thou sittest thee down abroad, thou shalt dig 
 therewith, and shalt turn back and cover that which cometh 
 from thee." 
 
 In mines, tunnels, canal cuttings, brickyards, and similar 
 works sanitary closets should be placed wherever there is 
 likely to be a need for them, and their use insisted upon. 
 In the tropical climate of warm, moist mines this is essen- 
 tial on account of the unusually favorable conditions for the 
 development and continued existence of the larvae in such 
 places. 
 
 It is instructive to see what can be accomplished with dif- 
 ferent methods of prophylaxis on the lines described. In 
 several mines in England, Belgium, and Germany efforts 
 have been made on such a scale as permits useful con- 
 clusions. 
 
 At the Dolcoath mine of Cornwall, when Boycott and 
 Haldane {Journal of Hygiene^ vol. 9, November, 1909, pages 
 264 — 270) began their investigations in 1902, the following 
 conditions prevailed: 
 
 ''Without exhaustive search they found among the seven 
 hundred and fifty miners employed underground fourteen 
 men with less than 50 percent hemoglobin, and nineteen 
 more with less than 75 percent. The general pallor of the 
 
PROPHYLAXIS. 199 
 
 men as a whole was very striking, and complaints of short- 
 ness of breath on climbing ladders were frequent. The dis- 
 ease was a material hindrance in carrying out the work of 
 the mine. Examinations of the men who complained of no 
 symptoms showed that practically every underground 
 worker was infected. The sanitary circumstances of the 
 mine were extremely unsatisfactory. There were no special 
 arrangements for the reception of excreta underground, and 
 the whole of the workings were extensively soiled with 
 feces. 
 
 ''Industrial efficiency was obviously confronted here with 
 a problem of some importance. The steps taken to escape 
 the consequences of ankylostomiasis were simple, practical, 
 and apparently efficacious. ... It was, in the great 
 majority of cases, very easy to cure those actually sick by 
 the repeated administration of appropriate anthelmintics. 
 The effects of this treatment have been entirely gauged by 
 the clinical results. No serious attempt has been made to 
 ascertain whether all the worms had been killed in any 
 particular case if the man's general condition improved so 
 far that he was able to return to work. Having been re- 
 stored to a condition of efficiency, the men, therefore, re- 
 turned to work in a place which was still infected. They 
 were, of course, reinfected again and again; any return of 
 symptoms was noted at once and corrected by .a dose of 
 thymol. In this way actual sickness from ankylostomiasis 
 has been practically abolished." 
 
 At the same time steps were taken to introduce sanitary 
 reforms into the underground workings. In 1905 a special 
 rule was established by the secretary of state for metal- 
 liferous mines in Devon and Cornwall, as follows: 
 
 "The owner, agent, or manager shall cause a sufficient 
 
-00 HOOKWOEM DISEASE. 
 
 number of suitable sanitary conveniences to be provided 
 above and below ground in suitable and convenient places 
 for the use of the persons employed, and to be kept con- 
 stantly in a clean and sanitary condition, and no persons 
 shall relijCve his bowels below ground elsewhere than in 
 these conveniences. No person shall soil or render unfit 
 for use in any way any convenience or sanitary utensil or 
 appliance provided for the use of the persons employed. ' ' 
 
 In 1904 such sanitary appliances were actually in use in 
 Dolcoath in the form of loose buckets or pails, which could 
 easily be brought to the surface, emptied, and cleaned. In 
 1908 ''the conditions underground had been immensely im- 
 proved, the pails were properly used, and it was very un- 
 common for the men to fail to use them. . . . We could 
 find no feces where, as previous experience had shown, they 
 would be most probably found. The general appearance of 
 the men was quite different, and there was none of the 
 anemia which had been so obvious five years before. On 
 carefully going through two-thirds of the underground 
 hands we found only one case of definite anemia in the per- 
 son of a boy. There was only one man away from work 
 with symptoms which could possibly be due to ankylos- 
 tomiasis." Examinations showed, however, that 76 per- 
 cent of the hands examined were infected, so that the im- 
 proved sanitary condition had put an end to material ill- 
 ness, but had hardly any effect on the number of men in- 
 fected. ''The sanitary pail system has, therefore, evidently 
 had a great effect in reducing the inf ectivity of the mine. ' ' 
 
 Boycott and Haldane compare the results with the more 
 intensive measures taken in Belgium and Westphalia. In 
 the latter every hookworm carrier, as well as patient, is 
 searched out, kept away from work on compensation wages, 
 and treated until repeated examinations fail to show any 
 
PROPHYLAXIS. 201 
 
 eggs in the feces. He is then allowed to return to under- 
 ground work; but the workings are still infective, and he 
 "becomes reinfected and the whole process has to be gone 
 through again and again." 
 
 In mines, more than most other places, disinfection of 
 the ground might seem possible, but the conditions in large 
 and old mines are such as to make this very difficult. As 
 has been shown in Chapter III, hookworm larvae are diffi- 
 cult to attack. In the laboratory they will live more than 
 a year. In coal water they live two or three weeks, and 
 have been found alive in the sludge of mines closed up for 
 ten months. They are sensitive to many disinfectants, but 
 there is difficulty in applying disinfectants to miles of mud 
 and water, and to wet timbers. It is also difficult to find 
 efficient disinfectants that will not vitiate the air, or injure 
 the boots of the men or the plant in the mine. Many sub- 
 stances have been tried; Belger alone experimented with 
 41. Ferrous sulphate in 1-percent solution is one of the 
 most promising, and is more effective than cupric sulphate; 
 silver nitrate, 0.05 to 0.025, and sodium hydrate or potas- 
 sium hydrate in 1-percent solution kill quickly. Manga- 
 nates and permanganates have a decided effect, but are too 
 costly and oxidize too rapidly to be useful. The efficacy of 
 sodium chloride has, however, been shown by Boycott and 
 Haldane and by Calmette, while Manouvriez and Tirelli 
 have shown that mines with saline waters do not become in- 
 fected with hookworm, and in some mines or tunnels it 
 might be found useful. 
 
 Boycott and Haldane admit the superiority of the Ger- 
 man system in reducing the number of hookworm carriers. 
 This system, as mentioned above, is one of active search 
 for ova in feces, with treatment followed up, and education 
 of the men. It was taken up after sanitation had been tried 
 and failed. The failure depends, in part, upon the difficul- 
 
202 HOOKWORM DISEASE. 
 
 ties mentioned. In tlie coal mines of the Ruhr Basin in 
 Westphalia the proportion of infected men fell as follows : 
 
 1904 13,861 
 
 1905 4,024, or 18 per 1,000 
 
 1906 3,123, or 11 per 1,000 
 
 1907. ?. 1,851, or 6 per 1,000 
 
 1908 1,171, or 3 per 1,000 
 
 In the coal field of Liege, under the care of Lambinet and 
 Malvoz, the proportion fell from 26 percent to 4 percent in 
 two years. 
 
 In Brennberg, Goldmann saw a reduction from 85 percent 
 in 1895 to 8 percent in 1904. 
 
 Toth in Schemnitz (Hungary) found the miners' wages 
 increased 60 percent after prophylactic measures were car- 
 ried out. 
 
 Bruns, from Dortmund, Germany, reported a reduction in 
 the proportion of infected miners from 35 percent to 0.1 — 
 0.2, or from 14,716 cases to 1,252. 
 
 While all these improvements have been very costly, they 
 are profitable in the end, and they indicate the task that a 
 country infested with hookworm has in order to become 
 free from the tax on life and health caused by that parasite. 
 
 In the open country chemical disinfection is almost out of 
 the question. Lime in quantities sufficient only for fer- 
 tilizer would not be very efficient. In larger amounts it is 
 one of the best, as it combines heat with disinfection. Salt 
 and other more powerful disinfectants would either kill 
 vegetation or be dangerous to live stock, while the cost 
 would prohibit their use. 
 
 In hookworm countries the winter cold does not kill 
 larvae. Oliver froze them repeatedly, and kept them frozen 
 for six days, but after gentle thawing they revived and gave 
 rise to stronger and more vigorous larvae than those not so 
 treated. 
 
PEOPHYLAXIS. 203 
 
 Direct sunlight can kill them, bnt nsually only when it 
 dries them up. They resist the sun in northern Europe, 
 and, although Leichtenstern could not find them in the clay 
 of brickyards, they find in some parts of such places more 
 favorable environment. 
 
 Drying land by ditching or drainage would do good in 
 many places. Plowing is useful in some cases, and in 
 others the grass may be burned over to kill the larvse. 
 
 Sugar fields were found by the Porto Eico Commission 
 to be rarely the sources of infection, the plowing and sun 
 causing the death of the larvae. Tobacco fields also are 
 only slightly dangerous. 
 
 The larvae are killed in deep or moving water, but can 
 live for long periods in shallow water along the edges of 
 streams — just the places that are used for wading, or in 
 some countries by washerwomen and water-carriers — and in 
 small puddles. Moist earth — especially if sandy, so as to 
 retain moisture, or shaded b}^ vegetation — offers ideal con- 
 ditions for the life of larvae, and should be treated accord- 
 ingly in hookworm countries. 
 
 3. Prevention of infection by larvae. — On account of the 
 difficulty of preventing the life and development of larvae 
 in places where men, women, and children work, it is essen- 
 tial to lessen the danger of infection by education. We 
 believe that the problem can never be solved without this. 
 From the history of some other sanitary movements in 
 America it is possible that the importance of this will not be 
 recognized by health officers and legislative bodies. It is 
 interesting to see the views of Ashford and King, formed 
 among a people that might be considered even less capable 
 than our own of education in matters of sanitation. Stat- 
 ing that education would make unnecessary the laws re- 
 garding latrines, they tell how laborers in Porto Rico an- 
 noyed their foreman by asking for latrines, and from that 
 
204 HOOKWORM DISEASE. 
 
 island, with its melanclioly history of ignorance and oppres- 
 sion, they write: 
 
 '^Law is not the instrument best fitted to compel a man 
 to be cle^n and live np to the rules of hygiene. Legisla- 
 tion concerning such matters would lie dormant in the 
 statute books until people learn to appreciate the phi- 
 losophy and spirit that originate such measures." 
 
 Every one living in a hookworm country should be taught 
 the essential facts about hookworms and their effects. Act- 
 ual specimens, charts and diagrams, illustrations of pa- 
 tients before and after treatment, and clear descriptions 
 should be available and used frequently by health officers, 
 school teachers, and all others who may have the authority 
 or opportunity. 
 
 It is a reflection on the common sense of the country that 
 we have for years been spending time and money teaching 
 school children the evil effects of alcohol, tobacco, pork, 
 and coffee, while the children were in many cases being 
 killed by hookworms before they were tempted to drink 
 whisky or even to smoke. It is especially important here 
 to emphasize the fact that skin infection is the most serious 
 danger — the method of infection par excellence, as it has 
 been called. Formerly much stress was laid upon mouth 
 infection, which, though rare on the whole, may occur. 
 People should, therefore, be warned against soiling the 
 mouth with muddy hands; eating with muddy hands; eat- 
 ing muddy vegetables or fruit; drinking muddy water, or 
 drinking from muddy receptacles; accidental swallowing 
 of water while bathing ; earth eating ; carrying home muddy 
 clothes that might soil the hands of wife or child; cleaning 
 muddy boots; crawling of children on the earth, which they 
 put into their mouths; handling mud-bedraggled dresses; 
 
PROPHYLAXIS. 205 
 
 eating of sweets made in dirty houses. The danger is es- 
 pecially great with wet or moist earth. But it can not be 
 too often repeated that in the great majority of cases in 
 America ground itch is the origin of hookworm infection. 
 
 It is fortunate that most people living in hookworm dis- 
 tricts know ground itch by that name or one of its 
 synonyms, and realize where and how they contract it. If 
 such people could be taught that ground itch is the usual 
 beginning of hookworm disease, the skin lesion would as- 
 sume an importance far greater than it now has, and it 
 should be much easier to induce methods of prevention. In 
 our opinion the first and most important measure to be 
 undertaken in the crusade against hookworm disease in 
 America is wide dissemination of the facts regarding 
 ground itch, conveying the information that when ground 
 itch is prevented there will be no hookworm disease. 
 
 Where ladders are used in infected mines, the workmen 
 must be warned against the danger of infection either 
 through the skin of the hands and arms, or the mouth by 
 putting infected food or the fingers into the mouth. Mine 
 timbers have been found infected as high as a meter above 
 the ground. 
 
 Gardeners, and those who handle vegetables or fruit that 
 may be infected, should be warned about hand or hand-to- 
 mouth infection. 
 
 Bathing in common in tubs should not be practiced by 
 workmen, such as miners, or country children. Shower 
 baths should be used. 
 
 In all occupations — such as mining, farming, or garden- 
 ing — where hookworm prevails, placards and other notices 
 should be posted, warning the hands against the danger of 
 skin infection, as well as of soil or water contamination in 
 general. 
 
 In hookworm localities the habit of going barefoot should 
 
206 HOOKWORM DISEASE. 
 
 be avoided. The danger of a single experience, as in wad- 
 ing, should be clearly understood. Those who work in in- 
 fected soil — as in mines, tunnels, or fields — should realize 
 the danger of defective boots. It is also possible that boots 
 soaked f&r hours in hookworm infected water may be pene- 
 trated by larvae. Bass found kid gloves could be pene- 
 trated, and Tenholt found that old boots harbored the 
 larvae. Various substances have been recommended for 
 the treatment of boots, such as grease or water-proofing 
 material. 
 
 The larvae sink so rapidly in water that drinking from 
 deep pools does not involve much danger. 
 
CHAPTEE X. 
 
 TREATMENT. 
 
 Ground itch is usually treated by somebody other than 
 the physician, or not at all. Of the home remedies may be 
 mentioned bathing the feet in hot salt water, mullein tea, 
 ''red oak ooze," application of peach tree leaf poultices, 
 various salves and ointments, including application of fresh 
 turpentine from pine trees, etc. Another favorite remedy, 
 esjpecially for the fissured toes, is to tie around them a wool 
 cord saturated with tallow. Bentley recommends in the 
 papular and early vesicular stages of the disease the ap- 
 plication of a strong solution of salicylic acid in collodion 
 or alcohol. This will cause the eruption to dry up, and cut 
 short the attack of the disease to one or two days. If pus 
 has formed, the pustules should be opened up and disin- 
 fected with pure carbolic acid, silver nitrate, or nitric acid. 
 When great swelling occurs, it may be necessary to make a 
 few free skin incisions and then to use hot foot baths. 
 
 Dalgetty advised the application of a strong solution of 
 lime and sulphur, or a strong phenyl (benzol) solution; also 
 recommended as a wash, 10 parts, with soap 5 parts, and 
 water to make 100 parts ; or the affected area may be painted 
 with coal-tar to prevent infection with pyogenic bacteria. 
 
 Stiles cpiotes the following from an anonymous writer in 
 the Journal of Tropical Medicine (1900) : 
 
 "The indications are to get the case as soon as possible; 
 to carefully cleanse the foot by soaking it in warm antisep- 
 tic solution; then open the vesicles with sharp-pointed scis- 
 sors, snij) the loose skin away, and finally wash the parts 
 
 207 
 
208 HOOKWOKM DISEASE. 
 
 with carbolic acid solution (1 to 40), and treat the resulting 
 ulcer with carbolic acid, phenyl oil, zinc ointment, etc., ac- 
 cording to circumstances. The soaking, washing, and dress- 
 ing operations are repeated once or twice daily, and heal- 
 ing takes place in eight or nine days in favorable cases. ' ' 
 
 The larvae remain in the skin so short a time before they 
 get into the deep circulation, and entirely out of reach of 
 local remedies, that it is not practical to make applications 
 that would even promise to affect them. Only symptomatic 
 treatment, therefore, is to be instituted. The most dis- 
 tressing symptom is terrible itching, which often causes the 
 patient to do considerable harm by scratching, producing 
 raw, inflamed areas, especially in the folds between and 
 beneath the toes. Deep fissures may occur. These often 
 become infected and pus is formed. Any antiseptic sooth- 
 ing application may be of service for the itching and to pre- 
 vent secondary infection. The following is recommended: 
 
 I^ Salicylic acid 5 grains. 
 
 Zinc oxide ointraent 2 drains. 
 
 Vaseline 2 drams. 
 
 Mix. 
 
 Sig. : Apply locally, twice daily. 
 
 It is especially important to keeiD the foot bandaged or 
 covered to prevent scratching and rubbing. Frequent hot 
 bathing seems to hasten the healing process. This is prob- 
 Sihlj due to the increased circulation induced, hastening re- 
 moval of the toxic substances causing the irritation. 
 
 The laity should be taught that the common ''toe itch" or 
 ground itch is not a trivial matter, but that a physician 
 should be consulted at once. Proper advice and treatment 
 at this time may prevent the development of severe disease 
 later. An important function of the physician called to 
 treat a case of ground itch is to urge the patient to spit out 
 
TREATMENT. 209 
 
 everything coughed up for several days afterwards, ex- 
 plaining that swallowing the sputum probably means swal- 
 lowing larvae of dangerous worms. 
 
 Treatment Before Ova Appear in the Stools. 
 
 Whether treatment to kill worms in the intestinal canal 
 should be instituted before they have had time to mature 
 and begin laying can not be stated positively. Ashford and 
 King say they know of many cases in which thymol given 
 previous to maturity of the worms failed to expel them, and 
 believe with Leichtenstern and other German writers that 
 this may be due to the better protection given the small 
 worms by mucus and folds of mucous membrane. If we 
 recall the development of the worms in the gut, little or no 
 result could be expected from treatment until after the 
 infection had existed for several days at least. Though it 
 has been shown experimentally that larvae may reach the 
 lungs in three hours, it may require considerably more time 
 for them to reach the bowel, as is shown in Chapter III, and 
 when they do reach it they are still in the encysted con- 
 dition, in which they are able to resist chemical agents 
 wonderfully well. They were found by Looss nine, ten, 
 and eleven days after infection in blood cysts and still in 
 the encysted condition. Lambinet states that the encysted 
 larvae are not killed in a 2-percent solution of corrosive sub- 
 limate after an exposure of six hours, nor in a 25-percent 
 sulphuric acid solution in three-quarters of an hour. We 
 do not know of any experiments to determine the effect of 
 thymol on encysted larvae, but from the foregoing we think 
 it is not likely to kill them. Bruns concluded, after months 
 of laboratory experimentation with every sort of chemical 
 disinfectant, that none has yet been found to kill the en- 
 capsuled larvae so surely that it can be practically used. 
 
210 HOOKWORM DISEASE. 
 
 At least as early as about fourteen or fifteen days after 
 infection the worm is i^rovided with a buccal capsule, 
 whereby it attaches itself to and feeds on the mucous mem- 
 brane. From this time on the parasite is just as much ex- 
 posed to the action of drugs as it is after maturity and egg 
 production are established. Our personal experience does 
 not permit us to speak with certainty on this point, but we 
 believe from the above facts that treatment should be begun 
 fourteen or fifteen days after the infection, and that satis- 
 factory results will follow. The same treatment should be 
 instituted after an attack of ground itch as if eggs were 
 jDresent in the stools. Two or three courses of thymol or 
 beta-naj)htol should be given about one week apart. This, 
 we believe, would get rid of most, if not all, of the worms 
 before they reach maturity and have done much harm. 
 The stools should be examined at the proper time, and from 
 two to three months after the attack of ground itch, for 
 eggs of any worms that may have escajDcd previous treat- 
 ment. 
 
 Treatment of Hookworms in the Intestine. 
 
 It is important to understand the conditions that must be 
 met in the treatment of hookworm infection. The worms, 
 three-eighths to three-fourths of an inch long, lie in the 
 small intestine, especially the jejunum. The head and some- 
 times one-fiith or more of the body of the worm is buried 
 in the mucosa, and the whole body surrounded and pro- 
 tected by any food that may be in the gut, but especially by 
 thick and tenacious mucus, which is almost always present. 
 The normal amount of mucus is increased by the irritation 
 produced by the feeding of many worms. Remedies used 
 against the worms affect or kill them by local action, and 
 the first stejD in the treatment is to remove this protection 
 of chyme and mucus, so the drug may come in contact 
 
TREATMENT. 211 
 
 With the worms. To secure an empty alimentary canal is 
 not easy. One who has had occasion to examine stools 
 passed after the bowels are supposed to have been thor- 
 oughly emptied by a purgative must be impressed with 
 this fact. Sometimes large evacuations, containing recog- 
 nizable food remams, occur. The upper portions of the gut 
 can be pretty thoroughly freed from food material by a 
 large dose of some salts —Rochelle, Epsom, or Glauber's. 
 On theoretical grounds, and as the result of clinical experi- 
 ence, we believe that sodium sulphate dissolves and removes 
 the intestinal mucus best. Many believe that calomel or 
 calomel and podophyllm are better. The Porto Rico 
 Anemia Commission tried podophyllin extensively for the 
 initial purge, but concluded that it had no advantage over 
 sodium sulphate, and that its drastic action may be harmful 
 to weak patients. It is highly recommended by German 
 writers for its destructive action on the worms when given 
 in large doses. In the usual doses, up to 3 centigrams (1/2 
 grain), it has no such action. Lambinet recommends jalap 
 and calomel as a preliminary purge. Lutz gives 1/2 gram 
 (7 1/2 grains) calomel and 2 grams (30 grains) alcoholic 
 extract of senna leaves one-half day before beginning the 
 specific treatment (thymol). Sandwith does not give any 
 preliminary purgative, considering it unnecessary. Die- 
 minger considers the preliminary purge unnecessary, espe- 
 cially when male fern is the anthelmintic employed. By hav- 
 mg a patient abstain from everything except the most easily 
 digested diet, like milk, for twenty-four hours, and giving 
 an ounce of sodium sulphate at least four hours after the 
 last feeding, the upper bowel is usually pretty well cleared 
 of food and mucus. More certain results can be had by giv- 
 ing another similar purgative twenty-four hours before this 
 one. Ashford and King did not consider preliminary diet- 
 ing practical with their Porto Rico cases, or especially need- 
 
212 HOOKWOEM DISEASE. 
 
 ful. Almost all other authors advise light diet or fasting 
 the day before specific medication is employed. It may not 
 be practical in many instances, we admit, but we believe it 
 is always advantageous if there is no distinct contraindica- 
 tion. After the preliminary preparation, the drug selected 
 to kill or expel the worms is to be given as soon as the peri- 
 stalsis from the purgative has ceased, usually six to eight 
 or ten hours. Thymol, beta-naphtol, and male fern are the 
 drugs most often employed. Thymol, first used against 
 ankylostoma duodenale by Bozzolo, is by far the most gen- 
 erally used in America and England, and, in view of the 
 almost invariably satisfactory results obtained when prop- 
 erly administered, it seems all that could be desired. 
 
 Dose of Thymol. 
 
 The dose of thymol for internal use, according to the 
 United States Disi^ensatory, is 2 to 10 grains. It is only 
 slightly (1:1,100) soluble in water or the gastric and intes- 
 tinal juices, and therefore little absorption occurs when it is 
 given undissolved and on an empty alimentary canal. Used 
 as a vermifuge, it is not intended to be absorbed, and is 
 used in much larger doses. Up to 8 grams, or 120 grains, a 
 day have been taken for several days without disturbance 
 of digestion or intoxication. 
 
 Leichtenstern recommended two or three doses of 30 
 grains each at two-hour intervals for several days; Giles, 
 25 grains in alcoholic solution morning, noon, and night; 
 Scheube, 60 to 120 grains, divided into four doses, adminis- 
 tered one and one-half hours apart and followed in twelve 
 hours by a purgative; Lutz, 30 grains, repeated once or 
 twice at two-hour intervals; Mosler and Peiper, 30 to 150 
 grains in three to six doses during the day; Sandwith, 1 
 gram (15 grains) of thymol at 6 p. m. and another similar 
 
TREATMENT. 213 
 
 dose the next clay at 6 a. m. At 8 a. m. about 1 ounce (30 
 grams) of magnesium sulphate is given. The patient is on 
 fever diet the first day, but gets his full dinner at noon the 
 second day. Manson gives 30 to 120 grains of thymol in 
 divided doses within three or four hours. 
 
 Ashford and King do not believe it necessary or justifi- 
 able to administer more than 60 grains of thymol at a time, 
 or to repeat oftener than once a week. Sandwith says the 
 same thing. 
 
 Sixty grains to an adult is the amount almost universally 
 employed in this country for a course of treatment of hook- 
 worm disease. The dose for children should be in propor- 
 tion to the size or apparent age. Ashford and King's table 
 of doses, which we recommend, is as follows: 
 
 Ages. Grains. 
 
 Under 5 years old in size 7% 
 
 5 to 10 years old in size 15 
 
 10 to 15 years old in size 30 
 
 15 to 20 years old in size 45 
 
 20 to 60 years old 60 
 
 Over 60 years old 30 to 45 
 
 Unfavorable conditions — such as great weakness, ex- 
 treme anemia, diarrhea, cardiac depression, preg-nancy, and 
 dropsy — may require a still smaller dose than that indicated 
 by the size. 
 
 Mode of administration of thymol. — It is customary to 
 give the drug in two or three "broken" doses, and to give 
 them one or two hours apart in order to prolong the pres- 
 ence of the thymol in the upper bowel. 
 
 Thymol occurs in coarse crystals. As it acts only when 
 in contact with the parasites, it is more effective if fimely 
 powdered. This can be done in a few minutes in a mortar 
 with pestle, or on a slab with a spatula. It tends to pack 
 together under pressure, or in the mucus in the intestine. 
 To prevent this, sugar of milk or other inert soluble sub- 
 
214 HOOKWORM DISEASE. 
 
 stance should be mixed with it. Lindeman suggests equal 
 parts of thymol and sugar of milk, and we find that this 
 insures the proper crumbling or breaking up of the con- 
 tents of the capsule or wafer when the latter is dissolved. 
 
 We have often found in the stools of patients who have 
 taken thymol, coarse lumps, and a few times the entire con- 
 tents of a tightly packed capsule. 
 
 Thymol has a pungent, acrid taste, and burns the mouth 
 and throat. It should, therefore, be given in cachets, 
 wafers, or capsules. A No. capsule will hold, without 
 packing unduly, 5 grains of thymol of the mixture of equal 
 parts of thymol and milk sugar. 
 
 When necessary to administer it to children who can not 
 swallow capsules or wafers, it may be satisfactorily given 
 suspended in mucilage of acacia or some simple syrup. 
 Burning, nausea, and even vomiting may be caused by the 
 presence of the pungent thymol in the stomach. Vomiting 
 can usually be prevented by determination on the part of 
 the patient, by lying on the right side to hasten the passage 
 of the medicine through the pylorus, and by refraining from 
 drinking much water. After the thymol has presumably 
 had time to pass the part of the small bowel where the 
 worms are — that is, two or three hours — it can not longer be 
 of service, and should be gotten rid of by another brisk 
 purgative of salts to prevent its absorption. As thymol is 
 soluble in oil, castor oil should never be used for this pur- 
 pose. The purgative is not to move out the worms, but 
 specifically to move out the th^anol. All the worms passed 
 are dead, and not much would be gained by hastening their 
 removal from the bowel after they have been killed. Suf- 
 ficient thymol may be absorbed to be harmful if allowed to 
 remain long enough. Besides oils, other solvents — such as 
 alcohol (tinctures, whisky, wines, brandy, beer), ether, 
 gl^'^cerine, turpentine, acetic acid (vinegar), chloroform — 
 and larc'e amounts of water should be avoided. 
 
TREATMENT. 215 
 
 Patient to remain in bed. — On account of the increased 
 tendency to vomit and tlie marlved increase of toxic symp- 
 toms from thymol when patients are up, all of them should 
 be required to remain in bed until the thymol is moved off. 
 Either the bedpan or commode should be used in the room. 
 We have seen several patients get up and walk about 
 against this instruction without experiencing the slightest 
 inconvenience, but Sandwith says that before adopting this 
 precaution several instances occurred in which patients 
 were brought back from the water-closets collapsed or 
 fainting. 
 
 Diet during thymol treatment. — In order to have the ali- 
 mentary canal remain clear while the thymol is present, ab- 
 solutely no food or drink should be allowed, except water, 
 from the time the preparatory purgative is given until the 
 purgative following the thymol has acted well. If the 
 patient is very weak and feels faint, or if the burning in the 
 stomach is excessive, a little warm broth or coffee may be 
 allowed. We do not employ these, however, except very 
 rarely. When one or two free movements have occurred 
 after the last purgative, the patient may begin to eat, and 
 his diet need not be restricted unless there is some special, 
 indication. He waits now several days, usually a week, be- 
 fore taking another course. In the interval the diet should 
 be full and the most nutritious compatible with the patient's 
 digestive ability, which is usually good. 
 
 Selection of time for giving treatment. — For apparent 
 reasons, Sunday is a very convenient day on which to give 
 the treatment, especially to working people, school children, 
 etc., as recommended by Stiles. It is also convenient to 
 give the preparatory purge at night and to begin the thymol 
 early the next morning. The patient then loses little sleep 
 the first night, and finishes the treatment before the next 
 night. 
 
216 HOOKWORM DISEASE, 
 
 We give our patients the following instructions, the closes 
 being for an adult: 
 
 All of Saturday have milk or other light diet. 
 
 Saturday, 8 or 9 p. m., take sodium sulphate, 1 ounce. 
 
 Sunday, 6 a. m., 20 grains thymol. 
 
 Sunday, 7 a. m., 20 grains thymol. 
 
 Sunday, 8 a. m., 20 grains thymol. 
 
 Sunday, 10 a. m., 1 ounce sodium sulphate. 
 
 Until 4 p. m. do not eat or drink anything but water, and 
 but little of that. Eemain in bed. 
 
 After 4 p. m. rise and eat what you want and do what- 
 ever you feel like doing. 
 
 Thymol may affect the patient unfavorably in three gen- 
 eral ways — by intoxication, by irritating the kidneys, and 
 by irritating the stomach and intestine. 
 
 Thymol intoxication symptoms. — The effects of absorp- 
 tion of a large amount of thymol are headache, weakness, 
 dizziness, tinnitus, nausea; rapid, weak pulse, and some- 
 times sweating of the face or body; cyanosis of lips and 
 fingers. The temperature in one instance fell 5 to 10 de- 
 grees F. Frequently none of these symptoms are felt until 
 the patient gets out of bed. The intensity of the symptoms 
 must, of course, depend on the amount of thymol absorbed 
 and the individual susceptibility. Thymol is soluble in al- 
 cohol and volatile oils, and these should be rigidly inter- 
 dicted. In fact, the patient should be instructed absolutely 
 not to swallow anything except water, and to drink only a 
 small quantity of that. Many cases of intoxication are due 
 to drinking too much water. The importance of this is 
 often overlooked. Thymol is sufficiently soluble in water, 
 about 1/2 grain to the ounce, for the patient to absorb a 
 toxic dose if he drinks large quanties of water. The infre- 
 quent occurrence of toxic symptoms from thymol given in 
 the doses mentioned is suggested by the fact that the 
 
TREATMENT. 217 
 
 authors have treated several hundred cases without ever 
 seeing more than a little dizziness and weakness as a result. 
 We have heard, however, of alarming s^Tnptoms, but not of 
 any fatal cases. In one instance a family of four children 
 was poisoned by the usual doses of thymol calculated ac- 
 cording to their ages. The symptoms were weakness, diz- 
 ziness, fainting, and unconsciousness. One child fainted 
 when returning from the water-closet and the other three 
 got out of bed and came to her assistance, but each one 
 fainted, and it was necessary to carry all four of them back 
 to bed. All had been given castor oil two hours after the 
 last dose of thymol, and the one who fainted first had eaten 
 a slice of bread and butter. In six hours afterward they 
 were all in the yard playing. Two days after the poison- 
 ing the urine was examined and found free from albumin. 
 We have several times noted that patients who complain of 
 dizziness and other symptoms of intoxication seem to re- 
 cover and feel well remarkably early after the purgative 
 acts well and food is taken. They are usually able to get 
 up at once, and, though unpleasant recollections of the re- 
 cent experience remain, the symptoms have entirely dis- 
 appeared. 
 
 Eecently a university student treated by our colleague. 
 Dr. Gage, took 60 grains of thymol and two hours afterward 
 a drink of whisky to "wash down" the dose of salts. There 
 followed several free movements during each of this and 
 the next three days. The patient was up and felt fairly 
 well, but a little weak. On the fifth day he had a mild col- 
 lapse, with dizziness and severe headache lasting a few 
 hours. Eructations tasting strongly of thymol occurred 
 frequently. During the next three days several dysenteric 
 stools were passed. It was eight or ten days before the 
 patient felt entirely well in his head and in his bowels. 
 The eructations of thymol and mild collapse five days after 
 
218 HOOKWORM DISEASE. 
 
 it had been taken indicate that it had not been eliminated 
 in this instance, in spite of several free bowel movements. 
 
 Pregnancy contraindicates the administration of thymol, 
 except under the greatest care, for fear of producing abor- 
 tion, which it occasionally does. Nephritis and consider- 
 able edema are also contraindications. 
 
 Ashford and King note that in very edematous patients 
 the effect of large doses of thymol is particularly harmful. 
 By the next day the edema is much increased and often in- 
 volves the brain. Albumin and casts are increased in 
 nephritic cases when large doses of thymol are admin- 
 istered. 
 
 We saw, however, a very severe case of hookworm dis- 
 ease in a child of 16 who had 60 percent of moist albumin 
 by the Purdy acetic acid and ferrocyanide test when she 
 was given 30 grains of thymol. No untoward results were 
 noted, and 2,760 imcinariae were expelled. Three days after 
 the thymol was given the urine showed only 18 percent of 
 albumin by the same test. The effect of thymol on the 
 normal gastro-intestinal canal is occasionally burning epi- 
 gastric pain, nausea, and vomiting, and more or less diar- 
 rhea. If diarrhea or dysentery already exist, they are 
 promptly aggravated by large doses. In several instances 
 we have seen loose bowels, lasting two or three days, follow 
 administration of thymol. One case had six to twelve 
 movements a day for six days. The rectum and anus are 
 irritated by tlnTiiol passing out with the feces, and, if 
 hemorrhoids or fissures are present, this symptom is much 
 increased. 
 
 The degree of debility must be taken into account when 
 cousidering the size of the dose for a given case. A very 
 weak subject should receive not more than 15 to 30 grains 
 the first dose, Avhich will usually relieve him so that he can 
 resist a full dose next time. Some English writers do not 
 
TREATMENT. 219 
 
 believe tlie small doses accomplish much, but actually large 
 numbers of worms are sometimes expelled as a result of 
 them. 
 
 The Porto Rico Anemia Commission treated 112,580 cases 
 of hookworm disease during the years 1904 to 1907 in- 
 clusive, all, except relatively few, with thymol, and after 
 this extensive experience advise placing the thymol in the 
 hands of patients to carry home and take according to 
 directions. Boycott and Haldane, as well as many other 
 recent writers, have had no dangerous symptoms such as 
 were described by some early observers, probably from giv- 
 ing oil or alcohol after the thymol. 
 
 Treatment of toxic S5miptoms produced by thymol. — Car- 
 diac stimulants, such as a hypodermic of a small dose of 
 morphine (1/6 grain) and atrophine (1/120 grain), or 
 strychnine (1/30 grain), or digitalin (1/100 grain), are of 
 service in combating toxic symptoms. Hot coffee has been 
 recommended for the weakness sometimes present. It is 
 customary with some to give strychnine and digitalis for a 
 day or two preceding the day thymol is given. This seems 
 unnecessary, except with extremely weak patients. Alco- 
 holic stimulants or tinctures by mouth must be rigidly 
 avoided on account of the danger of dissolving and render- 
 ing absorbable more thymol. One of the most important 
 things is to keep the patient lying down. If fainting occurs, 
 the head should be lowered, as in fainting from other causes. 
 The irritation to the kidneys by thymol, if properly given, 
 is negligible unless much is absorbed. Even then the irri- 
 tation rapidly subsides without treatment after the drug is 
 stopped. The diarrhea sometimes occurring after the 
 thymol administration soon passes off without requiring 
 treatment. If treatment is demanded, it should be along- 
 general lines. 
 
220 HOOKWORM DISEASE. 
 
 Results to be expected from thymol in expelling worms. — 
 
 The first course of thymol properly given usually gets rid 
 of 80 to 90 percent of all the worms present. So good a re- 
 sult is obtained only when proper preparation, etc., are 
 observed. One of the secrets of successfully treating intes- 
 tinal parasites of all descriptions is to secure an empty ali- 
 mentary canal before the specific drug is given. This is so 
 important that we do not doubt that it is often much better 
 to give a purgative on Friday night as well as on Saturday 
 night. There are, no doubt, other factors that prevent 
 marked success in some cases, such, for instance, as the 
 rapid carrying down of the thymol by peristalsis to below 
 the location of the worms. For this reason it is desirable 
 not to begin the thymol until peristalsis from the purgative 
 has ceased. It should, however, be given soon afterward 
 and before the worms are again protected by the mucus, 
 which soon forms. Cases are often met with in which no 
 eggs are found after one course of thymol, a fact known to 
 German miners seeking work. In many more a few remain 
 until three or four courses are given, and in a few cases six 
 to eight or ten courses are required to get rid of all of them. 
 It can be said, however, that, if persisted in, thymol will 
 always succeed. It is even a better specific for hookworm 
 disease than quinine is for malaria. 
 
 In a very extensive experience reported by Ashford and 
 King, 97.8 percent of those who expelled all their uncinarias 
 received thymol five times or less. Of these 41.8 percent ex- 
 pelled all after one treatment, 32.1 percent after two treat- 
 ments, 14.2 percent after three treatments, 6.8 percent after 
 four treatments, and 2.8 percent after five treatments. Of 
 4,474 cases which received thymol, 81.1 percent expelled all 
 uncinariae, but, subtracting 507 who never returned or 
 ceased to return after two or more treatments, this percent- 
 age rises to 91.5 percent. Sandwith cured 95 percent of 185 
 
TKEATMENT. 
 
 221 
 
 cases of ankylostomiasis with five or less doses of thymol. 
 The cures in the 185 cases were effected in the following 
 manner : 
 
 Number After number of 
 
 cured. treatments with thymol. 
 
 42 1 
 
 58 2 
 
 43 3 
 
 25 4 
 
 9 5 
 
 4 6 
 
 2 7 
 
 2 8 
 
 It would seem, therefore, that the old world hookworm is 
 about as easy to expel as the American variety. 
 
 In our own experience about one-half of all cases have 
 been cured of all their worms with three courses of thymol; 
 several have required five, six, and seven treatments, and 
 one required ten full treatments. In the case already men- 
 tioned, 2,760 worms were expelled after one treatment, but 
 the highest number counted in any other case was 1,054. 
 
 We have often been impressed with the fact that many, 
 in this country at least, do not fully appreciate that the 
 treatment must generally be repeated several times before 
 all worms are expelled. The complaint is made that, though 
 some worms are expelled after a course of thymol, the 
 patient is not cured. We would reply that few other dis- 
 eases are cured by a single day of treatment. 
 
 Repetition of treatment. — On account of the irritation to 
 the alimentary canal and kidneys produced by thymol, most 
 authors agree that it should not be repeated oftener than 
 once a week, unless there is some special indication for it. 
 We have, however, several times given a course of thymol 
 every third or fourth day for several times, and have not 
 seen any harm result therefrom. We believe it is a good 
 plan to give three treatments one week apart, and, after 
 
222 HOOKWORM DISEASE. 
 
 waiting about a week, to examine the feces for ova. Usu- 
 ally in mild or medium cases none will be found. If any are 
 found, treatment must be repeated. It must be remem- 
 bered that sometimes ovulation is suspended temporarily 
 after thymol has been administered, and, if symptoms per- 
 sist, the feces should again be examined in three or four 
 weeks after the last treatment. The result of the treatment, 
 can thus be best determined. 
 
 Other Methods of Treatment. 
 
 Beta-naphtol. — Beta-naphtol, as advocated by Bentley, is 
 given with the same precautions, preparation of patient, 
 and the same after-treatment as with thymol. Colbert had 
 one patient who expelled 4,016 worms from one dose of beta- 
 naphtol. Beta-naphtol, however, seems to act well only 
 when the preliminary purgation and fasting have been car- 
 ried out thoroughly. If food is taken, very poor results are 
 often obtained. Ashford and King concluded that thymol 
 was superior to beta-naphtol where the patient was not 
 under control, and state that they were obliged to abandon 
 the use of the latter for walking patients on this account. 
 They speak of several instances in which, after repeated 
 doses of beta-naphtol were given, eggs were persistently 
 present in the feces, which cleared up after a single dose of 
 thymol. Bentley states that he abandoned thymol two 
 years before to use beta-naphtol, and has used it in several 
 thousand cases with excellent results. The dose is one-half 
 that of thymol — viz., 30 grains for an adult. It frequently 
 is successful in expelling worms, but in many patients who 
 took their medicine at home the Porto Rico Anemia Com- 
 mission found the number of worms expelled far less than 
 when thjmiol was administered. On the other hand, a com- 
 parison of forty hospital cases treated with thymol and 
 thirty treated with beta-naphtol, in which the number of 
 
TREATMENT. 223 
 
 worms expelled was carefully determined, shows the results 
 from each drug to be about equal. The finding of the com- 
 mission shows the following percentages of all worms in the 
 intestinal canal of the patient that were expelled : 
 
 Percentage of 
 total number of 
 worms expelled. 
 
 After 1 dose of thymol 76.85 
 
 After 1 dose of beta-naphtol 72.24 
 
 After 2 doses of thymol 90.17 
 
 After 2 doses of beta-naphtol 88.12 
 
 , After 3 doses of thymol 95.28 
 
 After 3 doses of beta-naphtol 93.67 
 
 After 4 doses of thymol 96.57 
 
 After 4 doses of beta-naphtol 96.47 
 
 Beta-naphtol is more irritating to the kidneys, and some- 
 times sets up considerable nephritis. There is already al- 
 buminuria in many cases of uncinariasis, and it seems un- 
 wise to select a drug irritating to the kidneys. Unpleasant 
 dizziness often results from its use. It is, however, less 
 depressing than thymol. Its cost is only about one-tenth 
 that of thymol. 
 
 Oleoresin of male fern.— Male fern has been used for a 
 very long time as an anthelmintic in treating tapeworms, 
 and has recently been much used on the continent of Europe 
 in ankylostomiasis. Of 21,612 cases treated in Westphalia 
 by Bruns it failed to expel all the parasites in only 1.5 per- 
 cent, and in only 15 to 30 percent of cases was it necessary to 
 give a second dose. He records, however, four cases of 
 blindness resulting from its use. Tenholt cured 95.8 per- 
 cent of his cases with three doses. Lambinet gives a purge 
 of calomel and jalap powder the night before, and on the fol- 
 lowing morning "Duhourgan's teniafuge francais," which 
 is ext. filic. mas. 4 grams, chloroform 3 grams, ol. ricini 40 
 grams. This is given in two doses, with an hour's interval, 
 and repeated the next day. Toth recommends 45 to 75 
 
224 HOOKWORM DISEASE. 
 
 grains filix mass, with a glass of liqueur, every day for four 
 or five days. Dieminger noted icterus, gastritis, and gas- 
 tro-enteritis in some cases, as has also been noted by Toth 
 and others. 
 
 Leichtenstern says that 150 grains should not be ex- 
 ceeded.^ Ashford and King tried ethereal extract of male 
 fern in Porto Eico, and say that in some cases in which the 
 parasites were resistant to thymol this gave good results 
 and in others it did not. They suggest that the deleterious 
 effect of the hot climate of Porto Rico on the drug may have 
 been responsible for the variable results obtained. In their 
 1905 preliminary report they say: ''The highest number of 
 uncinarise expelled by either of these preparations (solid 
 extract and fluid extract) was eight, while a subsequent 
 administration of only three-fourths of the usual dose of 
 thymol brought away 3,686, and this in the very same 
 case." It seemed to cause more dizziness and nausea, and 
 patients complained that they felt sicker and weaker after 
 it than after thymol. The drug is very variable in its 
 potency, and, though we have not experimented with it in 
 this disease, we believe that its use will be limited, by its 
 much greater cost and other objections mentioned, to cases 
 that have failed to be cured by thymol or beta-naphtol. 
 The same preliminary treatment is to be given, and 75 to 
 150 grains of oleoresin of male fern administered in two 
 divided doses one hour apart. 
 
 Eucalyptus. — Phillips recommends eucalyptus oil com- 
 bined with chloroform and castor oil. The following is di- 
 vided into two doses and given one-half hour apart: 
 
 01. eucalypti 2.5 grams. 
 
 Chloroformi 3.5 grams. 
 
 01. ricini 41. grams. 
 
 This is not easily administered, and is very nauseating, 
 but has the advantage of causing live worms to be expelled. 
 
TREATMENT. 225 
 
 Podophyllin. — Podopliyllin is recommended by Neumann, 
 who thinks a certain amount of inflammation of the intes- 
 tine favorable, if not indispensable, for expulsion of the 
 worms. It is not very toxic, but irritating to the mucous 
 membrane. He gives two pills a day of 0.045 milligrams 
 of the active principle for four days, and, if ova still per- 
 sist, he gives male fern. 
 
 Other Drugs. — The following other drugs have been men- 
 tioned by various writers: 
 
 1. Juice of ficus doliaria, 3 to 6 teaspoonful doses; 
 much used in Brazil. 
 
 2. Powdered areca nut. 
 
 3. Jorrissen's preparation (a costly one) — terpine 1/2 
 gram, levigated sulphur 2 grams, condurango powder 1 
 gram. 
 
 4. Infusion of bark of acacia anthelmintica. 
 
 5. Oil of peppermint. 
 
 6. Kerosene oil. 
 
 7. Guaical carbonate. 
 
 8. Thymotal. 
 
 General Treatment. 
 
 Anemia. — The same general principles of the treatment 
 of anemia from other causes apply also to the treatment of 
 this, the most constant and the most prominent symptom 
 of hookworm disease. The most important measure is, of 
 course, to remove the cause, but, inasmuch as this often re- 
 quires three to six weeks, and the patient must rebuild his 
 blood during and after this time before he is back to normal 
 health, the question arises as to what treatment may be 
 made use of to hasten blood formation. Pure air, sunlight, 
 and nutrition are the most important factors. The class of 
 people affected, except miners and tunnel workers, are 
 blessed with air and sunlight. In most cases the removal 
 
226 HOOKWOKM DISEASE. 
 
 of a large portion of the worms is i3romptly followed by in- 
 creased appetite, and when the digestion and assimilation 
 are good, as they usually soon become, nutrition is increased 
 far above that required for a normal individual. We do not 
 believe special dieting necessary, or even api3reciably bene- 
 ficial, for mild or medium cases, but that liberal general diet 
 should be allowed. Very severe cases, with weak digestion 
 and assimilation, are no doubt benefited by a wise selection 
 of easily digested, nutritious diet suited to the individual 
 case. An abundance of good general diet is what is re- 
 quired for most rapid recovery. If we recall the fact that 
 not only is the blood below normal in hookworm disease, but 
 many of the other body tissues as well — bone, muscle, nerve, 
 hair, skin, etc. — the importance of a general mixed nutri- 
 tious diet becomes apparent. 
 
 The anemia in most cases is of the secondary type, with 
 low hemogiobm and low color index, which is generally 
 benefited by administration of iron, one of the essential ele- 
 ments in hemoglobin. Very mild and mild cases probably 
 are not appreciably affected by iron, but all moderate and 
 severe cases should take some form of this drug in the inter- 
 val between thymol treatments. AVe admit, with all other 
 writers on this subject, that the importance of iron in the 
 treatment of hookworm disease, compared with specific 
 treatment against the worm, is very small. We also believe 
 that recovery from almost any grade of hookworm anemia 
 will follow expulsion of the worms as certainly without as 
 with iron treatment, but that it will generally be more or 
 less hastened thereby. In fact, the anemia is benefited de- 
 cidedly by iron, either alone or combined with bitter tonics, 
 without any specific treatment being directed against the 
 worms. Many patients with chronic severe uncinariasis 
 give the history of taking iron tonics or reduced iron year 
 after year. They get run down, weak, and more anemic every 
 
TREATMENT. 227 
 
 spring, but get sufficient relief from iron to carry them 
 through the summer, never, however, getting entirely well. 
 Lookiug back over an experience of many years spent in a 
 section of country heavily infected with this disease, we 
 recall several families that we now know were severely in- 
 fected, and that bought year after year their supply of re- 
 duced iron, which was kexDt in the country stores. We re- 
 call that another method of administering iron was to place 
 some nails, or iron scraps and scales from the blacksmith 
 shop, in a bottle with vinegar, with or without some bark 
 and herbs added, for a bitter tonic. Some old man or old 
 woman of the neighborhood, frequently a grandmother of 
 several families, was supposed to know best how to make 
 these "spring tonics," which generally contained iron. 
 Since the country has settled up, and railroads and towns, 
 and drugstores and more doctors and patent medicines have 
 come in, there is far less of this self-medication, but the 
 point we desire to make is that iron is sufficiently beneficial 
 in hookworm disease, without the worms being treated, to 
 direct the patients themselves to continue to use it. 
 
 The history of Dr. T. B. Ford, who practiced for many 
 years in a heavily infected section of Mississippi, is inter- 
 esting in this connection. Dr. Ford (now retired) was a 
 close observer, and much cleverer than the average country 
 practitioner. Long before hookworm disease was diag- 
 nosed in this country he had learned that there was a spe- 
 cific anemic disease, the cause of which he did not know. He 
 could not cure it, but it was always benefited by iron and 
 quinine pills, which he made up himself. They were made 
 of reduced iron, quinine sulphate, and extract of gentian. 
 He frequently varied the proportions to meet, as he thought, 
 special indications, but, as we remember it, each pill con- 
 tained from one-half to one grain each of the iron and 
 quinine. The disease was so prevalent in that country, and 
 
228 HOOKWOEM DISEASE. 
 
 the benefit derived from "Dr. Ford's iron and quinine 
 pills" so apparent, that they were known by the laity for 
 thirty or forty miles around to be a specific remedy for this 
 unknown disease. 
 
 There is evidence that iron hastens blood reconstruction 
 and none that it interferes with it, or is otherwise harmful; 
 therefore some form of iron should be given in moderate or 
 severe anemia cases. Stiles believes that it should not be 
 given between the first and second treatments with thymol, 
 in order to impress on the patient the fact that the thymol 
 is actually the source of benefit and must be continued. The 
 patient usually improves so much during the first week that 
 any skepticism he may have had as to the correctness of 
 the diagnosis is dispelled. The same principles would gov- 
 ern the selection of the form of iron here as in the treatment 
 of any other secondary anemia. Blaud's pills, five grains, 
 t. i. d., and iron (reduced), quinine, and gentian, 1/2 to 1 
 grain of each, t. i. d., are recommended. Sandwith gives 
 7 1/2 grains of sulphate of iron t. i. d., the best results being 
 obtained when this is preceded by extract of bone marrow 
 for about a week. 
 
 A few cases of long standing and usually severe hook- 
 worm disease develop the pernicious type of anemia, with 
 high color index, and are not benefited by iron, as would be 
 expected. Many of them recover very slowly, or never re- 
 turn to a perfectly normal blood condition. They are bene- 
 fited by arsenic in the form of Fowler's solution, and should 
 take five to ten drops t. i. d. over long periods of time, with 
 occasional short intervals of rest. Such a case, age 24, first 
 seen four years ago, gave a history indicating hookworm 
 disease since early childhood, and the feces showed what 
 we considered a mild infection, which was confirmed by the 
 expulsion of twenty-four worms following 60 grains of 
 thymol, after which no eggs could be found on several ex- 
 

 
 
 CHART 
 
 1. 
 
 
 
 
 
 
 Eosino- 
 
 
 
 Hemo- 
 
 
 Color 
 
 philes, 
 
 D 
 
 ate. 
 
 globin. 
 
 Red cells. 
 
 index. 
 
 percent. 
 
 May 
 
 4,1906. 
 
 ..48 
 
 2,010,000 
 
 1.2 
 
 18 
 
 May 
 
 11, 190G. 
 
 ..45 
 
 2,100,000 
 
 1.1 
 
 16 
 
 May 
 
 25,1906. 
 
 ..52 
 
 2,250,000 
 
 1.2 
 
 11 
 
 July 
 
 6,1906. 
 
 ..43 
 
 1,910,000 
 
 1.1 
 
 
 Sept. 
 
 14,1906. 
 
 ..50 
 
 3,214,000 
 
 0.8 
 
 8 
 
 Feb. 
 
 6, 1907 . 
 
 ..62 
 
 4,116,000 
 
 0.8 
 
 4 
 
 Nov. 
 
 12,1907. 
 
 ..71 
 
 4,860,000 
 
 0.7 
 
 2 
 
 Jan. 
 
 21,1908. 
 
 ..84 
 
 4,920,000 
 
 0.9 
 
 4 
 
 July 
 
 11,1909. 
 
 ..81 
 
 4,741,000 
 
 0.9 
 
 1 
 
 TREATMENT. 229 
 
 aminations extending over six weeks' time. The blood con- 
 dition at different times and the treatment is shown by tlie 
 following table: 
 
 Treatment. 
 Thymol and Blaud's pills. 
 Thymol and Blaud's pills. 
 Thymol and Blaud's pills. 
 Fowler's solution. 
 Fowler's solution. 
 Fowler's solution. 
 Treatment discontinued. 
 Treatment discontinued. 
 Treatment discontinued. 
 
 There were present a few normoblasts, poikilocytosis, and 
 anisocytosis all the time until the arsenic treatment was 
 begun. It will be seen from the chart that there was no 
 gain until the arsenic was begun, regardless of the fact that 
 all the worms had been expelled and the patient took 
 Blaud's pills all the time. That the patient did not have 
 pernicious anemia is indicated by the nearly normal blood 
 for over two years. We have seen several patients showing 
 this type of anemia, and always making slow or no improve- 
 ment after curing them of their worms. In fact, we know 
 four cases still anemic, notwithstanding that two of them 
 were cured of their worms more than two years ago. Such 
 cases demonstrate that hookworm disease may in some way 
 damage the blood-making organs to an extent and in a way 
 that makes recovery impossible. Fortunately, such cases 
 are relatively very few in this country. The only way we 
 know to recognize them certainly is by proper blood exami- 
 nation. 
 
 Improvement After Treatment. 
 
 There are indeed few diseases in which treatment is fol- 
 lowed so promptly and so certainly by unmistakable im- 
 
230 HOOK WOE ^I DISEASE. 
 
 provement and recovery as is proper anthelmintic treat- 
 ment in hookworm disease. This is one of the few specifics 
 in medicine. The improvement in severe cases is marvelous. 
 A child with 15 or 20 percent hemoglobin, pale, " tallow- 
 faced, V one-fourth, one-third, or even one-half under 
 weight, undeveloped, dyspneic, and languid, can be seen to 
 gain weight, height, and color almost daily, and often with- 
 in two or three months be converted by a few doses of 
 thymol into a red-faced, hardy, healthy-looking child. He 
 often grows more in one year after treatment than he had 
 in the previous five, or even ten, years. Xature seems to 
 try to make up for lost time, and, though the child may 
 never attain the size he would have attained if he had not 
 been infected, the gain is great and rapid. Among the im- 
 portant factors determining the length of time necessary for 
 a patient to regain his health and completely recover, and 
 whether complete recovery can result, are: the severity of 
 the disease, the age of the patient, and individual recupera- 
 tive powers. It must be remembered that hookworm disease 
 may be produced by any number of worms from one up to 
 the lethal dose, sometimes as high as four or five thousand. 
 This very variable number of worms, as well as other fac- 
 tors, necessarily gives rise to differences of intensity. One 
 patient may be so badly affected as to require months to re- 
 cover or to preclude complete recovery, whereas another 
 may return to full health in a few days. TVe have long 
 been impressed with the influence of age on the recovery 
 from hookworm disease, young or growing patients always 
 gaining much more rapidly than adults. "We shall say more 
 about this below under ''height and weight." Individual 
 recuperative powers are here of much importance, as in 
 many other diseases. Two individuals cured of their worms 
 and having equal amounts of hemoglobin, of equal weight 
 and the same age, will often not return to the normal at any- 
 thing like the same rate. 
 
TREATMENT. 
 
 231 
 
 Blood. — The blood charts shown below are selected from 
 those published by Ashford and King, and some of oar own, 
 to show the rate of improvement in the blood during treat- 
 ment. It will be noted in most of the charts that the num- 
 ber of red cells increases faster than the hemoglobin, and 
 that they usually go considerably above the normal 
 5,000,000 long before the hemoglobin has reached normal. 
 It will also be noted that the eosinophiles come down more 
 slowly than the gain in red cells or hemoglobin. In fact, 
 they often remain high after the blood is otherwise normal. 
 "We know of several instances in which the eosinophile count 
 has been above 6 percent six, eight, and ten months after 
 all worms were expelled, and one instance of 17 percent two 
 years after successful anthelmintic treatment. 
 
 It may occur, as is shown in chart 4, that the eosinophiles 
 may increase for some time as the blood improves, espe- 
 cially in those severe cases in which the stimulus is suf- 
 ficiently great to exhaust the eosinophile-making ability, 
 which again revives after a part of the worms are gotten 
 rid of. 
 
 CHART 2. 
 
 Date. Hemoglobin. Red cells. White cells. 
 
 May 8 33 2,868,000 13,200 
 
 May 16 36 2,991,040 5,000 
 
 May 23 38 3,960,000 5,200 
 
 May 30 36 4,384,000' 3,200 
 
 June 6 50 4.000,000 9.200 
 
 June 13 56 4,541,600 .5,200 
 
 June 20 62 4,360.000 9.800 
 
 June 27 67 5,261,600 7,200 
 
 July 4 66 4,152,800 8,800 
 
 July 11 76 6,866,400 6,400 
 
 July 18 83 7,635,200 6,200 
 
 July 25 83 7,035,200 7,400 
 
 Aug. 1. 82 5,176,000 4.000 
 
 Aug. 8 75 5,924,000 5,000 
 
 Aug. 15 101 5,164,000 7,800 
 
 Eosinophiles. 
 16.8 
 22.4 
 16.4 
 17.6 
 
 8.6 
 14.8 
 10.8 
 
 8.8 
 
 9.0 
 
 6.0 
 
 4.8 
 5.6 
 8.6 
 
232 
 
 HOOKWORM DISEASE. 
 
 Date. 
 
 May 
 
 17 
 
 May 
 
 24 
 
 May' 
 
 31 
 
 June 
 
 7 
 
 June 
 
 14 
 
 June 
 
 21 
 
 June 
 
 28 
 
 July 
 
 4 
 
 July 
 
 21 
 
 Aug. 
 
 2 
 
 Aug. 
 
 3 
 
 Aug. 
 
 4 
 
 Aug. 
 
 6 
 
 
 CHART 3. 
 
 
 
 loglobi 
 
 in. Red cells. 
 
 White cells. 
 
 lOcisiiioijliiles. 
 
 28 
 
 3,480,000 
 
 7,400 
 
 10. 
 
 29 
 
 3,024,000 
 
 7,200 
 
 8. 
 
 30 
 
 3,864,000 
 
 5,000 
 
 8.8 
 
 50 
 
 3,981,600 
 
 11,600 
 
 4. 
 
 54 
 
 5,786,400 
 
 4,200 
 
 8.8 
 
 66 
 
 5,355,200 
 
 5,800 
 
 10,4 
 
 90 
 
 6,195,200 
 
 6,400 
 
 12. 
 
 103 
 
 6,088,000 
 
 17,800 
 
 6.4 
 
 115 
 
 
 
 
 95 
 
 
 
 7.2 
 
 92 
 
 
 
 8.8 
 
 92 
 
 
 
 6.4 
 
 85 
 
 
 
 6. 
 
 CHART 4. 
 
 Date. Hemoglobin. Red cells. 
 
 May 12 20 3,195,520 
 
 May 19 28 2,804,000 
 
 June 26 38 4,075,620 
 
 June 2 38 4,626,400 
 
 June 9 41 5,901,600 
 
 June 16 46 5,817,600 
 
 June 23 49 6,016,000 
 
 July 30 55 5,964,000 
 
 July 7 67 6,466,400 
 
 July 14 76 6,295,200 
 
 July 21 82 6,017,600 
 
 Aug. 28 83 6,364,000 
 
 Aug. 4 90 6,630,400 
 
 Aug. 4 104 6,724,000 
 
 White cells. 
 
 Eosinophiles. 
 
 6,400 
 
 .8 
 
 5,000 
 
 4.8 
 
 3,400 
 
 6.8 ■ 
 
 3,800 
 
 4.8 
 
 4,400 
 
 4. 
 
 4,400 
 
 7.2 
 
 5,000 
 
 8. 
 
 6,400 
 
 21.2 
 
 7,600 
 
 12.2 
 
 11,200 
 
 9.2 
 
 6,600 
 
 9.6 
 
 4,400 
 
 8. 
 
 8,800 
 
 2.2 
 
 7,800 
 
 1.6 
 
 
 
 CHART 5. 
 
 
 
 Date. 
 
 Hemos'lob 
 
 in. Red cells. 
 
 White cells. 
 
 Eosinophiles. 
 
 May 13 
 
 27 
 
 2,306,640 
 
 6,200 
 
 2. 
 
 May 20 
 
 19 
 
 1,688,000 
 
 5,000 
 
 .4 
 
 May 27 ... . 
 
 25 
 
 1,804,000 
 
 3,800 
 
 4.1 
 
 June 7 . . . . 
 
 27 
 
 2,964,000 
 
 4,800 
 
 
 July 13 ... . 
 
 30 
 
 2,977,600 
 
 8,600 
 
 .8 
 
TREATMENT. 
 
 23: 
 
 CHART 6. 
 
 Date. Hemoglobin. Red cell.s. White cells. Eosinopliiles. 
 
 May 13 14 1,226,400 4,200 8.4 
 
 May 20 21 1,746,640 5,000 4.4 
 
 May 27 21 2,084,400 5,600 2.8 
 
 June 3 22 2,504,000 4,000 3.2 
 
 June 10 22 2,377,600 3,600 2.4 
 
 June 17 32 2,555,200 2,800 3.2 
 
 June 24 , 52 4,461,600 4,200 3.2 
 
 July 1 41 3,528,800 4,200 2.8 
 
 July 8 65 4,870,400 8,200 1.2 
 
 July 15 78 4,852,800 4,200 5.6 
 
 July 22 78 4,352,000 5,600 3.2 
 
 July 29 68 4,417,600 6,200 3.2 
 
 Aug. 7 95 5,092,800 8,200 4.8 
 
 Aug. 14 109 5,190,400 10,800 2. 
 
 CHART 7. 
 
 Date. Hemoglobin. Red cells. 
 
 May 14 16 1,531,200 
 
 May 21 31 2,133,280 
 
 May 28 27 2,666,400 
 
 June 4 35 3,880,000 
 
 June 11 36 3,315,200 
 
 June 18 50 4,181,600 
 
 June 25 59 5,238,400 
 
 July 2 56 5,288,800 
 
 July 9 55 5,195,200 
 
 July 17 64 5,461,600 
 
 July 23 64 5,786,400 
 
 July 30 84 5,440,000 
 
 Aug. 6 . 90 6,688,000 
 
 Aug. 14 101 5,928,800 
 
 White cells. Eosinophiles. 
 
 7,800 
 6,200 
 
 11,600 
 9,800 
 7,400 
 
 14,800 
 
 11,200 
 7,400 
 
 11,200 
 8,600 
 4,800 
 9,600 
 6,800 
 
 10,200 
 
 18.3 
 
 14.4 
 
 18.4 
 
 28.4 
 
 22. 
 
 17.2 
 
 46. 
 
 22. 
 
 32.4 
 
 40. 
 
 18. 
 
 24.4 
 
 26. 
 
 28.4 
 
 Date. Hemoglcbin 
 
 Nov. 14 25 
 
 Nov. 22 35 
 
 Nov. 28 50 
 
 Dee. 8 65 
 
 Dec. 15 65 
 
 CHART 8. 
 
 
 
 n. Red cells. 
 
 White cells. 
 
 Eosinophiles. 
 
 2,457,500 
 
 5,035 
 
 16. 
 
 2,987,500 
 
 3,050 
 
 12. 
 
 3,603,125 
 
 2,431 
 
 21. 
 
 4,050,000 
 
 2,083 
 
 20. 
 
 5,005,600 
 
 3,024 
 
 18. 
 
234 
 
 HOOKWORM DISEASE. 
 
 CHART 9. 
 
 Age 14. Thymol once a week, no iron. 
 
 Date. Hemoglobin. Red cells. Eo.sinophiles. 
 
 May 19 34 3,671,400 19. 
 
 May"* 26 45 4,430,000 14. 
 
 June 2 61 
 
 June 9 60 5,200,000 6. 
 
 June 16 63 5,904,000 9. 
 
 June 23 82 6. 
 
 June 30 100 5,409,500 8. 
 
 CHART 10. 
 
 Age 32. Thymol. Cured of worms after two treatments. Blaud's pills. 
 
 Date. Hemog-lobin. Red cells. Eosinophiles. 
 
 Nov. 19 72 4,950,000 12. 
 
 Nov. 26 78 6. 
 
 Dec. 19 85 5,640,000 10. 
 
 Dec. 28 104 6,120,000 4. 
 
 CHART 11. 
 
 Age 16. Mild case. Thymol. Cured first course. No iron. 
 81 woi'ms collected. 
 
 Date. Hemoglobin. Red cells. Eosinophiles. 
 
 March 6 86 5,100,000 4. 
 
 March 19 94 6,244,000 4. 
 
 April 2 96 5,450,000 
 
 CHART 12. 
 
 Age 17, female. Thymol. Mild infection, pernicious anemia type. Fow- 
 ler's solution after first two weeks. History indicates hookworm 
 disease all her life. 
 
 Date- Hemoglobin. Red cells. Eosinophiles. 
 
 March 13 55 2,340,000 6. 
 
 March 29 51 2,422,000 3. 
 
 May 3 63 3,215,000 6. 
 
 June 4. 
 
 .Tune 19 61 4,752,000 4. 
 
 Sept. 22 88 5,420,000 
 
TREATMENT. 235 
 
 This case illustrates the slow (seven months) improve- 
 ment usually made by this kind of anemia.. Chart 1 shows 
 another case of this kind, in which it took nearly two years 
 for the blood to become approximately normal. Though 
 severe cases may require several months to return to a 
 normal blood condition, it is our belief that the average case 
 in this country reaches a normal red cell count and hemo- 
 globin index in one to three months, and very many mild 
 cases within one month. 
 
 Height and weight. — The growth in height is in propor- 
 tion to the amount of reduction and the age of the patient. 
 When patients are not more than two or three inches below 
 what they should be, this is usually gained if they are not 
 over 20 years old. When over 20 they may still grow, but it 
 is doubtful whether they ever reach the height due them. 
 In fact, we have seen many cases grow several inches in 
 height and several pounds in weight after they were 26 to 28 
 years old. One man 27 years old married while yet a boy 
 in size and appearance, and moved to town. Within a 
 couple of years he had grown so much that it was often 
 remarked that married life had made a man of him. This 
 occurred before we knew of hookworm disease, but subse- 
 quent familiarity with the disease and an opportunity to 
 examine the man's brother, and the knowledge that another 
 brother had died of undoubted hookworm disease, explain 
 the cause of his dwarfing. The gain in weight is even 
 more rapid sometimes than the gain in height. A 16-year 
 old boy under our observation gained twenty pounds in 
 weight and grew two inches taller in two months. Captain 
 J. F. Siler had one patient who gained thirty-five pounds 
 in one month. The foregoing were severe infections, but 
 we have often seen remarkable gains in weight and general 
 feeling by patients who had very mild infections. One 
 man gained nine pounds in one month after expelling only 
 
236 HOOKWORM DISEASE. 
 
 nineteen worms. Another man, 35 years old, gained nine- 
 teen pounds after getting rid of a mild infection. 
 
 Patients with severe disease and childish voices at 18 to 
 20 or 22 years old will usually have change of voice within 
 two or tliree months. 
 
 Pubic and axillary hair that have not started begin to 
 grow within two or three months if the patient is of proper 
 age. We have observed the beard to begin to grow at 29 
 years, and we believe it may later than this. 
 
 The mammae of girls develop rapidly in dwarfed patients, 
 and we have observed this after 24. No doubt this can 
 occur even later if the worms are gotten rid of. 
 
 At the end of our chapter on treatment we wish to em- 
 phasize that we must not lose sight of any other diseases 
 the patient may have when we are considering his treat- 
 ment. Curing hookworm disease may often benefit, but 
 will not cure, other diseases present. 
 
REFERENCES. 
 
 Affleck, 27 
 
 Agramonte, 37 
 
 Allesandrini, 106 
 
 Allyn, 29 
 
 Alvarez, 37 
 
 Annett, 68 
 
 Aporto, 113 
 
 Arnold, 31 
 
 Arslan, 113 
 
 Ashford, 31, 32, 59, 83, 93, 94, 
 
 132, 135, 151, 165, 172, 184, 
 
 209, 220, 222, 224 
 Austregesilo, 153 
 
 Baelz, 36 
 
 Bagly, 37 
 
 Bartlett, 27 
 
 Bass, 38. 39, 70, 92, 145, 146, 
 
 175, 177, 203 
 Baumler, 23 
 Behrend, 29 
 Belger, 67, 201 
 Bentley, 79, 140, 203, 222 
 Bilharz, 22, 100 
 Blaud, 228 
 Blickhahn, 29 
 Bondurant, 38 
 Boston, 29 
 
 Boycott, 34, 65, 179, 200, 201 
 Bozzolo, 22, 49, 212 
 Branch, 41, 42 
 Brims, 202, 209, 223 
 Butterworth, 146 
 
 Calmette, 79, 201 
 Castiglioni, 22 
 Chabert, 24 
 Chamberlain, 39 
 Claytor, 29, 37 
 Cobbold, 49 
 Colbert, 222 
 Cole, 38, 40 
 Colomiatti. 22 
 Concato, 22 
 Craig, 96 
 Creplin, 49 
 Crisafuli, 113 
 
 Dabney, 29 
 
 97, 
 203, 
 
 167, 
 
 Dalgetty, 203 
 
 Daniels, 95 
 
 Da Silva Pinto, 41 
 
 Deaderick, 39, 43 
 
 Dieminger, 166 
 
 Diesing, 49 
 
 Dobson, 36 
 
 Dock, 127 
 
 Dolley, 28 
 
 Drake, 27 
 
 Dubini, 20, 21, 48, 49 
 
 Duncan, 25 
 
 Dyer, 29 
 
 Edwards, 19 
 Elliott, 144 
 Ernst, 102 
 Swing, 186 
 
 Fearn'side, 99 
 Firket, 34 
 Ford, 227 
 Fort, 38 
 Frankel, 29 
 Frolich, 21, 48, 49 
 Fiilleborn, 41, 184 
 
 Gabbi, 106 
 
 Gage, 38, 39, 138, 177, 217 
 Galli-Valerio, 67, 69 
 Geddings, 25 
 Giles, 68, 212 
 Goldmann, 106, 202 
 Goldsmith, 36 
 Gotuzzo, 153 
 Goze, 21, 49 
 Grassi, 22, 77, 165 
 Griesinger, 22 
 Guthrie, 38 
 Gutierrez, 37, 59, 96 
 
 Haldane, 34, 65, 179, 200, 201 
 Hall, 29 
 
 Hammerschmid, 20 
 Harris. 38 
 Harrison, 38 
 Henry, 50 
 Herff. 29 
 Hermann. 67, 79 
 
238 
 
 REFERENCES. 
 
 Heusinger, 27 
 Hirsch, 24 
 
 Immermann, 23 
 
 King, 32, 59, 83, 93, 94, 97, 132, 135, 
 151, 165, 172, 184, 203, 209, 220, 
 222, 224 
 
 Kinyoun, 38 
 
 Kiilz, 35, 171 
 
 Labat, 19 
 
 Lambinet, 65, 79, 202, 209, 210, 223 
 
 Leichtenstern, 23, 43, 67, 70, 75, 99, 
 
 102, 136, 165, 209, 212, 224 
 Leidy, 28 
 Leiper, 41, 68 
 Lemann, 38, 127 
 Leuckhart, 23, 49, 59 
 Liefmann, 105 
 Lindeman, 214 
 Loeb, 104 
 Looss, 32, 41, 49, 60, 67, 69, 70, 75, 
 
 99, 102, 108, 110, 138, 164, 172, 209 
 Lussana, 113 
 
 Lutz, 59, 60, 144, 151, 211, 212 
 Lyell, 25 
 
 McConnell, 36 
 McGehee, 149 
 MacDonald, 153 
 Maliverria, 22 
 Malvoz, 202 
 Manouvriez, 201 
 Manson, 155, 212 
 Manuel, 37 
 Mathias, 36 
 Menche, 151 
 Mink, 56 
 Molin, 49 
 Mohlau, 29 
 Mosler, 212 
 
 Neumann, 225 
 Nichols, 42 
 Nicholson, 38 
 Nieden, 151 
 Noc, 41 
 Noe, 77 
 
 Oliver, 35, 67, 69, 202 
 Oppenheim, 153 
 Ozzard, 68 
 
 Paletti, 22 
 Parona, 22, 165 
 Peipper, 212 
 Pepper, 158, 171 
 Perner, 67 
 
 Perroncito, 22, 62 
 Perry, 38 
 Philbrick, 195 
 Pieri, 63, 69, 77 
 Piso, 19 
 Pitt, 24 
 Posnett, 36 
 Preti, 106, 108 
 Previtera, 33 
 Prowe, 37 
 Pruner, 22 
 
 Railliett, 50 
 Rankin, 38 
 Romani, 38 
 Ross, 68 
 
 Sandwith, 97, 211, 212, 228 
 
 Sangalli, 108 
 
 Schaeffer, 30 
 
 Schaudinn, 79 
 
 Scheube, 212 
 
 Schifone, 41 
 
 Schneider, 49 
 
 Schuffner, 69, 79 
 
 Signorelli, 152 
 
 Siler, 39 
 
 Smith, Allen J., 29, 39, 60, 65, 97, 
 
 104, 111 
 Smith, Claude A., 38, 63, 70, 79, 138, 
 
 144, 170, 172 
 Scare, 154 
 Sonderegger, 22 
 Stiles, 21, 30. 37, 40, 42, 49, 59, 75, 
 
 156, 167, 178, 186, 228 
 
 Tebault, 29 
 
 Telemann, 171 
 
 Tenholt, 42, 67, 79, 97, 156, 203, 223 
 
 Toth, 202, 223 
 
 Turner, 42 
 
 Vadala, 106 
 Van Durne, 138 
 Vannini, 113 
 Von Linstow, 59, 63 
 Von Siebold, 22, 49 
 
 Wainwright, 42 
 
 Warfield, 38 
 
 Weiss, 186 
 
 Whipple, 37. 97, 99, 102, 108, 111 
 
 Winthrop, 38, 40 
 
 Wood, 27 
 
 Wucherer, 22, 60 
 
 Yates, 29, 96, 112 
 Yoshida, 148 
 
INDEX. 
 
 Acute cases of hookworm disease, 
 
 134 
 Administration of thymol, mode of, 
 in treatment, 213 
 pregnancy contraindicates, 218 
 Africa, hookworm disease in, 35 
 Agchylostoma as name for hook- 
 worm, 21 
 Age as a factor in hookworm dis- 
 ease, 230 
 Air, effect of, on ova, 65 
 America, uncinaria as name for 
 
 hookworm in, 49 
 Anatomy, pathologic, 94 
 Anemia, arsenic in, 228 
 
 as a symptom in hookworm dis- 
 ease, 135 
 Blaud's pills in, 228 
 commission for study of, in Porto 
 
 Rico, 32 
 due to dirt eating, 146 
 Dr. Ford's iron and quinine pills 
 
 in, 227 
 effect of iron in, 228 
 Fowler's solution in, 228 
 in hookworm disease. 111 
 
 benefited by iron, 226 
 Investigations of, 20 
 miner's, 20 
 of secondary type in hookworm 
 
 disease, 226 
 progressive, characteristic of 
 
 hookworm disease, 17 
 secondary type of, 136 
 treatment of, in hookworm dis- 
 ease, 225 
 Animals, feces pass through diges- 
 tive tract of, 86 
 hookworm in, 50 
 
 infecting, 70 
 ova scattered by, 194 
 Ankylostoma duodenale as generic 
 name for hookworm, 49 
 as name for hookworm, 17 
 description of, 49 
 development of, 63 
 old world parasite, 41 
 Anthelmintic treatment, 230 
 Antilles, hookworm disease in the, 
 37 
 
 Appearances, post-mortem, in hook- 
 worm disease. See Post-mor- 
 tem appearance of hookworm 
 subject. 
 
 Appendix vermiformis, hookworm 
 in, 149 
 
 Appetite in hookworm disease, 146 
 perversion of, 146 
 
 Arabs, hookworm disease among, 43 
 
 Arsenic in anemia, 228 
 
 Arteries, post-mortem appearance 
 of, 95 
 
 Asia, hookworm disease in, 36 
 
 Australia, hookworm disease in, 36 
 
 Austria, hookworm disease in, 33 
 
 Autopsy of hookworm subject, how 
 to make, 96 
 
 B.ilLKAx peninsula, hookworm dis- 
 ease in, 33 
 Barefooted children exposed to 
 
 hookworm disease, 44, 92 
 Bass' method of centrifuging, 175 
 Belgium, hookworm disease in, 33 
 Beriberi, hookworm disease mistak- 
 en for, 183 
 Beta-naphtol, dose of, in treatment, 
 222 
 for expulsion of feces for exami- 
 nation, 177 
 treatment, 222 
 
 hookworms expelled in, 223 
 Blaud's pills in anemia, 228 
 
 in treatment, 229 
 Blood charts in hookworm disease, 
 229 
 in treatment, 229, 231 
 coagulation, conditions accelerat- 
 ing, 104 
 substance delaying, 105 
 feces contain traces of. 149 
 larvae in the, 82 
 post-mortem appearance of, 100 
 pressure in hookworm disease, 143 
 symptoms of, 135 
 
 of hookworm disease due to 
 loss of, 115 
 test for, in feces, 149 
 Blotting paper test for hookworm 
 disease, 178 
 
 239 
 
240 
 
 INDEX. 
 
 Bohemia, hookworm disease in, 20 
 Bone marrow, post-mortem appear- 
 ance of, 100 
 Brain, post-mortem appearance of, 
 
 100 
 Brazil, hooliworm disease in, 22 
 Bronchial tubes, larvae in, 82 
 
 Cases, acute, of hookworm disease, 
 
 chronic, of hookworm disease, 134 
 marked, of hookworm disease, 132 
 moderate, of hookworm disease, 
 
 132 
 slight, of hookworm disease, 132 
 Cause of hookworm disease, 17 
 Cells, vegetable, differentiation of 
 
 hookworm ova from, 169 
 Central America, hookworm dis- 
 ease in, 37 
 Centrifuge, concentration of ova 
 with, 172 
 preparing feces for, 172 
 Purdy, 172 
 Centrifuges, 172 
 Centrifuging, Bass' method of, 175 
 
 method of, 172 
 Certain diagnosis, 155 
 Characteristics of hookworm dis- 
 ease, 17 
 Charcot-Leyden crystals as guide in 
 
 prognosis, 185 
 Chewing tobacco as remedy for dirt 
 
 eating, 147 
 Children, barefooted, exposed to 
 
 hookworm disease, 44, 92 
 Chlorosis, Egyptian, hookworm dis- 
 ease compared with, 22 
 symptoms, hookworm disease like, 
 26 
 Chronic cases of hookworm disease, 
 134 
 hookworm disease, color of skin 
 in, 141 
 Circulatory system, symptoms of, 
 
 17, 142 
 Classification of hookworm, 49, 50 
 Clay as a factor in hookworm dis- 
 ease, 43 
 Clay eating, 146 
 
 Climate a factor in hookworm dis- 
 ease, 42 
 Closet. See Privy. 
 Coagulation, blood, conditions accel- 
 erating, 104 
 substance delaying, 105 
 Cold, effect of, on larvae, 202 
 
 on ova, 63 
 Commission for study of anemia in 
 Porto Rico, 32 
 
 Concentration of ova with centri- 
 fuge, 172 
 
 Conditions accelerating blood coag- 
 ulation, 104 
 
 Constipation in hookworm disease, 
 149 
 
 Construction of sanitary privy, 195 
 
 Count, eosinophile, in diagnosis, 178 
 
 Country schools not provided with 
 privies, 91 
 
 Cover glasses unnecessary in micro- 
 scopic examination, 160 
 
 Crystals, Charcot-Leyden, as guide 
 in prognosis, 185 
 
 Cuba, hookworm disease in, 37 
 
 Cure, hookworm disease capable of, 
 17 
 
 Danger of hookworm carriers, 191 
 Darkness, effect of, on ova, 65 
 Definition of hookworm carrier, 17 
 
 of hookworm disease, 17 
 Dermatitis produced by skin infec- 
 tion, 76 
 Description of ankylostoma duode- 
 nale, 49 
 of hookworm, 50 
 of nematodes, 47 
 of strongylidce, 47 
 Desiccation, effect of, on ova, 64 
 Development, hookworm disease re- 
 tards, 126 
 impaired, characteristic of hook- 
 worm disease, 17 
 of ankylostoma duodenale, 63 
 of larvae, 65 
 Dew poison, hookworm in, 79 
 Diagnosis, 155 
 by examination of stool after 
 
 treatment, 177 
 eosinophile count in, 178 
 mouth of hookworm feature for, 
 54 
 Diarrhea in hookworm disease, 149 
 Diet during thymol treatment, 215 
 Differentiation of embryos and lar- 
 va3, 165 
 of hookworm larvae from other 
 
 larvae, 168 
 of hookworm ova from other ova, 
 
 167 
 of hookworm ova from vegetable 
 cells, 169 
 Digestive system, symptoms of, in 
 hookworm disease, 17, 144 
 tract of animals, feces pass 
 through, 86 
 Dirt eating, 146 
 anemia due to, 146 
 cause of worms, 147 
 
INDEX. 
 
 241 
 
 Dirt eating — cont'd. 
 
 chewing tobacco as remedy for, 
 
 147 
 infectious, 28 
 
 in region of great lal^es, 27 
 in United States, 24 
 remedies for, 147 
 symptoms of, 25 
 Dirty fruit as a factor in hookworm 
 disease, 45 
 vegetables as a factor in hook- 
 worm disease, 45 
 Discharge of ova of worms charac- 
 teristic of hookworm disease 
 17 
 Discovery of hookworms, 20 
 Disease, hookworm. See Hookworm 
 disease, 
 hoolvworm, a filth disease, 192 
 symptoms of hookworm, altered 
 by other diseases, 154 
 Diseases, intercurrent, and compli- 
 cations, 187 
 Disinfectants, effect of, on larvae, 69 
 
 for hookworms, 201 
 Disinfection in mines, 201 
 Disposition of feces, 86 
 in absence of privies, 89 
 in mines, 91 
 Distribution and economic impor- 
 tance, 33 
 Divisions of hookworm, 49, 50 
 Dose of beta-naphtol in treatment, 
 222 
 of eucalyptus in treatment, 224 
 of male fern in treatment, 223 
 of podophyllin in treatment, 225 
 of thymol in treatment, 212 
 Drinking, excessive, ova diminished 
 by, 166 
 water as a factor in infection, 75 
 Dropsy in hookworm disease, 150 
 Dyspnea, symptoms of, 142 
 
 EcDYSis, first, of larvae, 74 
 
 second, of larvae, 74 
 
 third, of larvae, 85 
 Economic importance and distribu- 
 tion, 33 
 Effect of air on ova, 65 
 
 of cold on larvae, 202 
 
 of cold on ova, 63 
 
 of darkness on ova, 65 
 
 of desiccation on ova, 64 
 
 of heat on ova. 63 
 
 of iron in anemia, 228 
 
 of light on larvae, 203 
 
 of oxygen on ova, 64 
 
 of siuilight on ova. 65 
 
 Effect — cont'd. 
 
 of vaseline on larvae, 67 
 of water in mines, 35 
 of water on larvae, 203 
 Eggs, hookworm. See Ova. 
 Egypt, hookworm disease in, 22, 32 
 Egyptian chlorosis, hookworm dis- 
 ease compared with, 22 
 Elevation as a factor in hookworm 
 
 disease, 43 
 Embryology of hookworm, 02 
 Embryos and larvae, differentiation 
 
 of, 165 
 Encysted stage of larvae, 66 
 England, hookworm disease in, 33 
 Eosinophile count in diagnosis, 178 
 Eosinophiles as guide in prognosis, 
 184 
 in hookworm disease, 136 
 Eosinophilia present in worm infec- 
 tions, 180 
 Epigastric pain in hookworm dis- 
 ease, 144 
 Epithelium nourishment for hook- 
 worm, 85 
 Eucalyptus, dose of, in treatment, 
 224 
 treatment, 224 
 Evacuation, time for finding larvae 
 
 after, 170 
 Examination, beta-naphtol for ex- 
 pulsion of feces for, 177 
 kind of feces for, 157 
 microscopic, cover glasses unnec- 
 essary in, 160 
 going over slide in, 164 
 light necessary for, 163 
 magnification to be used in, 161 
 making preparation for. 158 
 number of slides in, 161 
 size of slides in, 159 
 time required for, 161 
 wet preparation to be used in, 
 161 
 obtaining feces for, 157 
 of feces for ova. See Ova. 
 of stool, diagnosis by, after treat- 
 ment, 177 ■ 
 thymol for expulsion of feces for, 
 177 
 Excessive drinking, ova diminished 
 
 by, 166 
 Experiments with larvae, 138 
 Expulsion of feces, beta-naphtol for, 
 for examination, 177 
 thymol for. for examination, 177 
 Extermination of hookworms in 
 
 prophylaxis, 190 
 Eyes, symptoms of, 151 
 
242 
 
 IXDEX. 
 
 Favokabie prognosis in proportion 
 
 to treatment, 188 
 Fatal cases of hookworm disease, 
 
 127 
 Fatality, occasional, of hookworm 
 
 disease, 17, 19 
 Feces, beta-naphtol for expulsion of, 
 for examination, 177 
 containitraces of blood, 149 
 disposition of, 86 
 in absence of privies, 89 
 in mines, 91 
 
 examining, for ova. See Ova. 
 hatching of ova in, by mixture, 72 
 kind of, for examination, 157 
 obtaining, for examination, 157 
 of infected persons source of in- 
 fection, 93 
 pass through digestive tract of 
 
 animals, 86 
 preparing, for centrifuge, 172 
 quantity of, passed varies with 
 
 conditions, 166 
 test for blood in, 149 
 thymol for expulsion of, for ex- 
 amination, 177 
 Flies, hatching of ova promoted by, 
 
 72 
 Food as a factor in infection, 76 
 
 in prognosis, 182 
 Ford's, Dr., iron and quinine pills 
 
 in anemia, 227 
 Fowler's solution in anemia, 228 
 France, hookworm disease in, 20, 33 
 
 Gain in height after treatment, 235 
 
 in weight after treatment, 235 
 Gastric secretions, investigations 
 
 of, 148 
 General treatment of hookworm 
 
 disease, 225 
 Generic name for hookworm, ankyl- 
 
 ostoma duodenale as, 49 
 Genito-urinary system, symptoms 
 
 of, 150 
 Germany, hookworm disease in, 33 
 Glands, hemolymph, post-mortem 
 appearance of, 100 
 male sexual, of hookworm, 57 
 mesenteric, post-mortem appear- 
 ance of, 100 
 Grades of hookworm disease, 132 
 Great lakes, dirt eating in regions 
 
 of, 27 
 Greek derivation for hookworm, 21 
 Ground itch, 91, 137 
 
 origin of hookworm infection, 205 
 percentage of, 93 
 treatment of, 207 
 Guam, hookworm disease in, 36, 79 
 
 HaakeiXwurji proposed as name 
 
 for hookworm, 21 
 Hatching of ova in feces by mix- 
 ture, 72 
 of ova, moisture as a factor in, 74 
 of ova promoted by flies, 71 
 of ova, requirements for, 71 
 of ova, shade as a factor in, 74 
 Hawaiian Islands, hookworm dis- 
 ease in, 36 
 Heart, lavvee in the, 82 
 
 post-mortem appearance of, 94 
 Heat, effect of, on ova, 63 
 Height and weight in hookworm 
 disease, 235 
 gain in, after treatment, 235 
 Hemoglobin estimation in hook- 
 worm disease, 135 
 Hemolymph glands, post-mortem 
 
 appearance of, 100 
 Hemolysis in hookworm disease, 107 
 Hemolytic toxins in hookworm dis- 
 ease, 106 
 Hemorrhage, hookworm causes, 102 
 hookworm causes greater, than 
 necessary for food, 104 
 Hemorrhages, ratio of, to number 
 
 of hookworms, 99 
 History of hookworm, 19 
 Hookworm, agchylostoma as name 
 for, 21 
 ankylostoma duodenale as name 
 
 for, 17 
 ankylostoma duodenale as generic 
 
 name for, 49 
 a parasite, 17 
 
 barefooted children exposed to, 92 
 belongs to family strongylidse, 46 
 to nematode class, 46 
 to sub-family strongylinse, 46 
 carrier, danger of, 191 
 definition of, 17 
 
 has mild case of hookworm dis- 
 ease, 119 
 causes hemorrhage, 102 
 
 greater than necessary for food, 
 104 
 classification of, 49, 50 
 description of, 50 
 differentiation of, larvpe from 
 
 other larvse, 168 
 discovery of, 20 
 disinfectants for, 201 
 divisions of, 49, 50 
 eggs. See Ova. 
 embryology of, 62 
 epithelium nourishment for, 85 
 eradication, requirements of, 191 
 Greek derivation for, 21 
 
INDEX. 
 
 243 
 
 Hookworm — cont'd. 
 
 haakenwurm proposed as name 
 for, 21 
 
 history of, 19 
 
 infecting animals, 70 
 man, 70 
 
 infection, cause of greater, in 
 tropics, 75 
 ground itch origin of, 205 
 relation of moisture to, 43 
 
 in animals, 50 
 
 in appendix vermiformis, 149 
 
 in dew poison, 79 
 
 in ground itch, 79 
 
 in Porto Rico, 30 
 
 in small intestine, 97 
 
 in the South, 30 
 
 in toe itch, 79 
 
 in water sore, 79 
 
 larvae, differentiation of, from 
 other larv£e, 168 
 
 male sexual glands of, 57 
 
 miner's anemia due to, 23 
 
 mouth of, feature for diagnosis, 54 
 
 mucosa normal food of, 108 
 
 mucus essential for, 20 
 
 necator Americanus as name for, 
 17 
 
 new world, 30 
 
 old world, 30 
 
 ova, 58 
 
 description of, 164 
 differentiation of, from other 
 
 ova, 167 
 differentiation of, from vegeta- 
 ble cells, 169 
 
 origin of scientific name for, 21 
 
 scientific name of, 17 
 
 subject, how to make autopsy of, 
 96 
 
 subject may present no recogniz- 
 able symptoms, 116 
 
 subject, post-mortem appearance 
 of, 94 
 
 sucking an important function of, 
 102 
 
 synonyms for, 18, 47 
 
 toxin caused by. 111 
 
 treatment, other drugs in, 225 
 
 treatment, other methods of, 222 
 
 ulcers caused by. 111 
 
 unclnaria as name for, in Amer- 
 ica, 49 
 
 vmcinaria duodenalis as name for, 
 17 
 
 uteri of, 57 
 
 zoologic features of, 46 
 Hookworms expelled in beta-naphtol 
 treatment, 223 
 
 Hookworms — cont'd. 
 
 expelled in thymol treatment, 223 
 
 extermination of, in prophylaxis, 
 190 
 
 number of, indicated by number 
 of ova in feces, 165 
 
 ratio of hemorrhages to number 
 of, 99 
 
 results from thymol in expellina-, 
 220 
 
 treatment of, in intestine, 210 
 
 when, cease to ovulate, 167 
 Hookworm disease a filth disease, 
 192 
 
 acute cases of, 134 
 
 age as a factor in, 230 
 
 among Arabs, 43 
 
 anemia as symptom in, 135 
 
 anemia in. 111 
 
 benefited by iron, 226 
 of secondary type in, 226 
 
 appetite in, 146 
 
 barefooted children exposed to, 44 
 
 blood charts in, 229, 231 
 
 blood pressure in, 143 
 
 blotting paper test for, 178 
 
 capable of cure, 17 
 
 cause of, 17 
 
 causes laziness, 124 
 
 characteristics of, 17 
 
 characterized as lazy disease, 152 
 
 chronic cases of, 134 
 
 clay as a factor in, 43 
 
 climate a factor in, 42 
 
 color of skin in chronic, 141 
 
 compared with Egyptian chloro- 
 sis, 22 
 
 constipation in, 149 
 
 definition of, 17 
 
 diarrhea in, 149 
 
 dirty fruit as a factor in, 45 
 
 dirty vegetables as a factor in, 45 
 
 discharge of ova of worms char- 
 acteristic of, 17 
 
 divisions of types of, 130 
 
 dropsy in, 150 
 
 effect of, on duration of life, 186 
 
 elevation as a factor in, 43 
 
 eosinophiles in, 136 
 
 epigastric pain in, 144 
 
 eyes in, 151 
 
 fatal cases of, 127 
 
 general treatment of, 225 
 
 genito-urinary system in, 150 
 
 grades of, 132 
 
 height and weight in, 235 
 
 hemoglobin estimation in, 135 
 
 hemolysis in, 107 
 
 hemolytic toxins in, 106 
 
244 
 
 IXDEX. 
 
 Hookworm disease — cont'd, 
 home of, in tropics, 23 
 hookworm carriers liave mild 
 
 cases of, 119 
 impaired development character- 
 istic of, 17 
 in Africa, 35 
 in Asia, 36 
 in Australia, 36 
 in Austria, 33 
 in Balkan peninsula, 33 
 in Belgium, 33 
 in Bohemia, 20 
 in Brazil, 22 
 in Central America, 37 
 in Cuba, 37 
 in Egypt, 22, 32 
 in England, 33 
 in France, 20, 33 
 in Germany, 23, 33 
 in Guam, 36 
 in Hawaiian Islands, 36 
 in Hungary, 20, 33 
 in Italy, 22, 33 
 in Mexico, 29, 37 
 in New Guinea, 36 
 in Panama, 37 
 in Philippines, 36 
 in Sardinia, 33 
 in Servia, 33 
 in Sicily, 33 
 in Spain, 33 
 in Switzerland, 23 
 in the Antilles, 37 
 in the South, 28 
 in United States, 24, 37 
 lactation imperfect in, 186 
 lactation in, 150 
 leucocytes in, 136 
 like chlorosis symptoms, 26 
 marked cases of, 132 
 mild type of, 122 
 mines a factor in, 42 
 mistaken for beriberi, 183 
 
 for malaria, 183 
 
 for nephritis, 183 
 
 for tuberculosis, 183 
 moderate cases of, 132 
 mortality of, 184 
 nervous system in, 152 
 occasionally fatal, 17, 19 
 occupation as a factor in, 44 
 other parasites in, 188 
 perforation of intestine in, 188 
 persons exposed to, 17 
 perversion of appetite in, 146 
 perversions in, 153 
 pneumonia intercurrent in, 187 
 
 Hookworm disease — cont'd, 
 post-mortem appearances in. See 
 Post-mortem appearance of 
 hookworm subject, 
 progressive anemia characteristic 
 of, 17 
 ■ psychic effects in, 153 
 pulse in, 143 
 range of latitude of, 33 
 retards development, 126 
 sandy soil as a factor in, 43 
 sections where, occurs, 17 
 severe type of, 125 
 
 how recognized, 127 
 sexual perversions in, 153 
 shade as a factor in, 43 
 slight cases of, 132 
 social position as a factor in, 44 
 spread of, 23 
 
 stricture of intestine in, 188 
 symptoms in. See Symptoms, 
 symptoms of, 17 
 
 altered by other disease, 154 
 circulatory system in, 17 
 digestive system in, 17 
 due to loss of blood, 115 
 due to toxin, 115 
 nervous system in, 17 
 treatment of anemia in, 225 
 uncinaria as name for, in Amer- 
 ica, 49 
 urine in, 150 
 Hungary, hookworm disease in, 
 20, 33 
 
 Impaired development characteris- 
 tic of hookworm disease, 17 
 Improvement after treatment, 229 
 Infection, drinking water as a fac- 
 tor in, 75 
 during rainj^ weather, 92 
 eosinophilia present in worm, 180 
 feces of infected persons source 
 
 of, 93 
 food as a factor in, 76 
 hookworm, cause of greater, in 
 tropics, 75 
 ground itch origin of, 205 
 relation of moisture to, 43 
 modes of, 70 
 mouth, 69, 70 
 
 prevention of, by larvae, 203 
 of soil, in prophylaxis, 192 
 privies source of, 86 
 skin, 69 
 
 by larvae-containing water, 45 
 only practical mode, 93 
 stage of larvae, 70 
 
INDEX. 
 
 245 
 
 Infection — cont'd, 
 through skin, 76 
 through wet shoes, 92 
 Intercurrent diseases and complica- 
 tions, 187 
 Intestinal canal, ova not hatched 
 
 in, 70, 71 
 Intestine, perforation of, in hook- 
 worm disease, 188 
 small, hookworm in, 97 
 stricture of, in hookworm disease, 
 
 188 
 treatment of hookworms in, 210 
 Intestines, post-mortem appearance 
 
 of, 96, 100 
 Intoxication symptoms, thymol, 216 
 
 treatment of thymol, 219 
 Investigations of anemia, 20 
 of gastric secretions, 148 
 Iron and quinine pills, Dr. Ford's, 
 
 in anemia, 227 
 Iron, anemia in hookworm disease 
 benefited by, 226 
 effect of, in anemia, 228 
 Italy, hookworm disease in, 22, 33 
 
 Joints, symptoms of, 137 
 
 Keenig's sign, 152 
 Kidneys, post-mortem appearance 
 of, 95 
 
 Lactation imperfect in hookworm 
 disease, 186 
 
 in hookworm disease, 150 
 Larvae and embryos, differentiation 
 
 of, 165 
 Larvae-containing water, skin infec- 
 tion by, 45 
 Larvae, development of, 65 
 
 differentiation of embryos and, 
 165 
 
 differentiation of hookworm, from 
 other larvae, 168 
 
 effect of cold on, 202 
 
 effect of disinfectants on, 69 
 
 effect of light on, 203 
 
 effect of vaseline on, 67 
 
 effect of water on, 67, 203 
 
 encysted stage of, 66 
 
 experiments with, 138 
 
 first ecdysis of, 74 
 
 infectious stage of, 70 
 
 in the blood, 82 
 
 in the bronchial tubes, 82 
 
 in the heart, 82 
 
 in the lungs, 82 
 
 moults in development of, 66 
 
 prevention of infection by, 203 
 
 Larvae — cont'd, 
 second ecdysis of, 74 
 temperature most favorable for, 
 
 42 
 third ecdysis of, 85 
 time for finding, after evacuation, 
 
 170 
 will penetrate leather, 206 
 Latrine. See Privy. 
 Laziness, hookworm disease causes 
 
 124 
 Lazy disease, hookworm disease 
 
 characterized as, 152 
 Leather, larvae will penetrate, 206 
 Leucocytes in hookworm disease, 
 
 136 
 Life, effect of hookworm disease on 
 
 duration of, 186 
 Light, effect of, on larvae, 203 
 
 necessary for microscopic exami- 
 nation, 163 
 Liver, post-mortem appearance of, 
 95 
 symptoms of, 141 
 Lungs, larvae in the, 82 
 post-mortem appearance of, 95 
 
 Magnification to be used in micro- 
 scopic examination, 161 
 Making preparation for microscopic 
 
 examination, 158 
 Malaria, hookworm disease mistak- 
 en for, 183 
 Male fern, dose of, in treatment, 223 
 treatment, 223 
 sexual glands of hookworm, 57 
 Man, hookworm infecting, 70 
 Marked cases of hookworm disease, 
 
 132 
 Mesenteric glands, post-mortem ap- 
 pearance of, 100 
 Method, Bass', of centrifuging, 175 
 of centrifuging, 172 
 Pepper's, for finding ova, 171 
 Telemann'iS, for finding ova, 171 
 Methods, other, in hookworm treat- 
 ment, 222 
 special, for. finding ova, 171 
 Mexico, hookworm disease in, 37 
 Microscopic examination, cover 
 glasses unnecessary in, 160 
 going over slide in, 164 
 light necessary for, 163 
 magnification to be used in, 161 
 making preparation for, 158 
 number of slides in, 161 
 size of slides in, 159 
 time required in, 161 
 wet preparation to be used in, 161 
 
246 
 
 INDEX. 
 
 Miner's anemia, 20 
 
 due to hookworm, 23 
 Mines as factor in hooliworm dis- 
 ease, 42 
 disinfection in, 201 
 disposition of feces in, 91 
 effect of water in, 35 
 Mixture, iiatcliing of ova in feces 
 
 by^72 
 Mode of administration of thiymol 
 in treatment, 213 
 of infection, 70 
 Moderate cases of hool^worm dis- 
 ease, 132 
 Moisture as a factor in hatching of 
 ova, 74 
 relation of, to hool^worm infec- 
 tion, 43 
 Mortality of hookworm disease, 184 
 Moults in development of larvae, 65 
 Mouth infection, 69, 70 
 
 of hookworm feature for diagno- 
 sis, 54 
 Mucosa normal food of hookworm, 
 108 
 post-mortem appearance of, 97 
 Mucus essential for hookworm, 20 
 
 Necatoe Americanus as name for 
 hookworm, 17 
 description of, 59 
 is new world parasite, 41 
 synonyms for, 59 
 Nematode class, hookworm belongs 
 
 to, 46 
 Nematodes, description of, 47 
 Nephritis, hookworm disease mis- 
 taken for, 183 
 Nervous system, symptoms of, in 
 hookworm disease, 17, 151, 152 
 New Guinea, hookworm disease in, 
 
 36 
 New world hookworm, 30 
 
 parasite is necator Americanus, 41 
 Number of hookworms indicated by 
 number of ova in feces, 165 
 of slides in microscopic examina- 
 tion, 161 
 
 Occupation as a factor in hook- 
 worm disease, 44 
 
 Old world hookworm, 30 
 
 parasite is ankylostoma duode- 
 nale, 41 
 
 Organs, symptoms on part of cer- 
 tain, 135 
 
 Origin of hookworm infection, 
 ground itch, 205 
 
 Other drugs in hookworm treat- 
 ment, 225 
 methods of hookworm treatment, 
 
 222 
 parasites in hookworm disease, 
 
 188 
 Ova absent after thymol treatment, 
 
 166 
 concentration of, with centrifuge, 
 
 172 
 description of hookworm, 164 
 differentiation of hookworm, from 
 
 other ova, 167 
 differentiation of hookworm, from 
 
 vegetable cells, 169 
 diminished by excessive drinking, 
 
 166 
 effect of air on, 65 
 effect of cold on, 63 
 effect of darkness on, 65 
 effect of desiccation on, 64 
 effect of heat on, 63 
 effect of oxygen on, 64 
 effect of sunlight on, 65 
 hatching of, in feces by mixture, 
 
 72 
 moisture as a factor in hatching 
 
 of, 74 
 not hatched in intestinal canal, 
 
 70, 71 
 number of hookworms indicated 
 
 by number of, in feces, 165 
 number of, passed in stool, 71 
 of hookworm, 58 
 of uncinaria Americana, 65 
 of uncinaria duodenalis, 65 
 of worms, discharge of, character- 
 istic of hookworm disease, 17 
 Pepper's method for finding, 171 
 present after thymol treatment, 
 
 166 
 requirements for hatching of, 71 
 scattered by animals, 194 
 shade as a factor in hatching, 74 
 special methods for finding, 171 
 Telemann's method for finding, 
 
 171 
 treatment before, appear in stool. 
 
 209 
 Ovulate, when hookworms cease to, 
 
 167 
 Oxygen, effect of, on ova, 64 
 
 Panama, hookworm disease in, 37 
 
 two kinds of hookworm in, 37 
 Pancreas post-mortem appearance 
 
 of, 96 
 Parasite, hookworm a, 17 
 
IXDEX. 
 
 247 
 
 Parasite — cont'd, 
 new world, is necator Americanus, 
 
 41 
 old world, is ankylostoma duode- 
 nale, 41 
 Parasites, other, in hookworm dis- 
 ease, 188 
 other than hookworms, 100 
 Pathologic anatomy, 94 
 Pathology, 94, 101 
 Patient to remain in bed during 
 
 thymol treatment, 215 
 Philippines, hookworm disease in, 
 
 36 
 Pepper's method for finding ova, 171 
 Percentage of ground itch, 93 
 Perforation of intestine in hook- 
 worm disease, 188 
 Persons exposed to hookworm dis- 
 ease, 17 
 Perversion of appetite in hookworm 
 
 disease, 146 
 Perversions in hookworm disease, 
 153 
 sexual, in hookworm disease, 153 
 Pills, Blaud's, in anemia, 228 
 in treatment, 229 
 Dr. Ford's iron and quinine, in 
 anemia, 227 
 Pneumonia intercurrent in hook- 
 worm disease, 187 
 prevalence of, in southern states, 
 187 
 Podophvllin, dose of, in treatment, 
 225 
 treatment, 225 
 Porto Rico commission, report of, 43 
 commission for study of anemia 
 in, 32 
 Post-mortem appearance of hook- 
 worm subject, 94 
 of arteries, 95 
 of blood, 100 
 of bone marrow, 100 
 of brain, 100 
 of heart, 94 
 
 of hemolymph glands, 100 
 of intestines. 96, 100 
 of kidneys, 95 
 of liver, 95 
 of lungs, 95 
 
 of mesenteric glands, 100 
 of mucosa, 97 
 of pancreas, 95 
 of skin, 94 
 of spleen, 95 
 of stomach, 96 
 Pregnancy contraindicates adminis- 
 tration of thymol, 218 
 
 Pregnancy — cont'd. 
 
 unfavorable element in prognosis, 
 186 
 Preparation, making, for micro- 
 scopic examination, 158 
 wet, to be used in microscopic ex- 
 amination, 161 
 Prevention of infection by larvae, 
 203 
 of soil infection in prophylaxis, 
 192 
 Privy, construction of sanitary, 195 
 sanitary, necessary in prophylax- 
 is, 194 
 Privies source of infection, 86 
 country schools not provided 
 
 with, 91 
 disposition of feces in absence of, 
 89 
 Prognosis, 182 
 
 Charcot-Leyden crystals as guide 
 
 in, 185 
 eosinophiles as guide in, 184 
 favorable, in proportion to treat- 
 ment, 188 
 food as a factor in, 182 
 pregnancy unfavorable element 
 in. 186 
 Progressive anemia characteristic 
 
 of hookworm disease, 17 
 Prophylaxis, 189 
 
 extermination of hookworms in, 
 
 190 
 prevention of soil infection in, 192 
 sanitary privy necessary in, 194 
 Psychic effects in hookworm dis- 
 ease, 143 
 Pulse in hookworm disease, 143 
 Purdy centrifuge, 172 
 
 QuAiS'TiTY of feces passed varies 
 with conditions, 166 
 
 Rainy weather, infection during, 92 
 
 Range of latitude of hookworm dis- 
 ease, 33 
 
 Ratio of hemorrhages to number of 
 hookworms, 99 
 
 Relation of moisture to hookworm 
 infection, 43 
 
 Remedies for dirt eating, 147 
 
 Repetition of thymol treatment, 221 
 reason for, 221 
 
 Report of Porto Rico Commission, 
 43 
 
 Requirements of hookworm eradica- 
 tion, 191 
 
 Respiratory system, symptoms of, 
 141 
 
248 
 
 INDEX. 
 
 Results from thymol in expelling 
 hookworms, 220 
 
 Saa'dy soil as a factor in hookworm 
 
 disease, 43 
 Sanitary privy, construction of, 195 
 privies necessary in prophyjaxis, 
 194 
 Sardinia, hookworm disease in, 33 
 Scientific Aame of hookworm, 17 
 
 origin of, for hookworm, 21 
 Schools, country, not provided with 
 
 privies, 91 
 Secondary type of anemia, 136 
 Servia, hookworm disease in, 33 
 Sexual glands, male, of hookworm, 
 57 
 perversions in hookworm disease, 
 153 
 Shade as a factor in hatching ova, 
 74 
 in hookworm disease, 43 
 Shoes, infection through wet, 92 
 Sicily, hookworm disease in, 33 
 Skin infection, 69 
 by larvte-containing water, 45 
 dermatitis produced by, 76 
 only practical mode, 93 
 Skin, infection through, 76 
 
 color of, in chronic hookworm 
 
 disease, 141 
 post-mortem appearance of, 94 
 Slide, going over, in microscopic ex- 
 amination, 164 
 Slides, number of, in microscopic 
 examination, 161 
 size of, in microscopic examina- 
 tion, 159 
 Slight cases of hookworm disease, 
 
 132 
 Social position as a factor in hook- 
 worm disease, 44 
 Soil, sandy, as a factor in hook- 
 worm disease, 43 
 Solution, Fowler's, in anemia, 228 
 Solvents to be avoided in thymol 
 
 treatment, 214 
 Southern states, prevalence of pneu- 
 monia in, 187 
 Spain, hookworm disease in, 33 
 Special methods for finding ova, 171 
 Spleen, post-mortem appearance of, 
 95 
 symptoms of, 141 
 Spread of hookworm disease, 23 
 
 cause of, 23 
 Stool, number of ova passed in, 71 
 treatment before ova appear in, 
 209 
 
 Stomach, post-mortem appearance 
 
 of, 96 
 Stricture of intestine in hookworm 
 
 disease, 188 
 Strongylidse, description of, 47 
 family, hooltworm belongs to, 46 
 synonyms for, 47 
 Strongylinte sub-family, hookworm 
 
 belongs to, 46 
 Substance delaying blood coagula- 
 tion, 105 
 Sucking an important function of 
 
 hookworm, 102 
 Sunlight, effect of, on ova, 65 
 Switzerlan(J, hookworm disease in, 
 
 22 
 Symptom, anemia as a, in hook- 
 worm disease, 135 
 Symptomatic diagnosis, 155 
 Symptomatology, 115 
 Symptoms in liookworm disease. 
 
 See Symptoms. 
 Symptoms, hookworm disease, like 
 chlorosis, 26 
 hookworm subject may present 
 
 no recognizable, 116 
 of blood, 135 
 
 of circulatory system, 17, 142 
 of digestive system, 17, 144 
 of dirt eating, 25 
 of dyspnea, 142 
 of eyes, 151 
 
 of genito-urinary system, 150 
 of hookworm disease, 17 
 
 altered by other diseases, 154 
 due to loss of blood, 115 
 due to toxin, 115 
 of joints, 137 
 of liver, 141 
 
 of nervous system, 17, 151 
 of respiratory system, 141 
 of skin, 137 
 of spleen, 141 
 
 on part of certain tissues and or- 
 gans, 135 
 thymol intoxication, 216 
 Synonyms for hookworm, 18, 47 
 for strongylidEe, 47 
 for necator Americanus, 59 
 System, circulatory, symptoms of, 
 17, 142 
 digestive, symptoms of, 17, 144 
 genito-urinary, symptoms of, 150 
 nervous, symptoms of, 17, 151 
 respiratory, symptoms of, 141 
 
 Telemann's method for finding ova, 
 171 
 solution necessary for, 171 
 
IXDEX. 
 
 1^4^ 
 
 Temperature most favorable for 
 
 larvae, 42 
 Test, blotting paper, for hookworm 
 
 disease, 178 
 Thymol, dose of, in treatment, 212 
 first use of, for hookworm, 212 
 for expulsion of feces for exami- 
 nation, 177 
 intoxication symptoms, 216 
 
 treatment of, 219 
 mode of administration of, in 
 
 treatment, 213 
 pregnancy contraindicates admin- 
 istration of, 218 
 results from, in expelling hook- 
 worms, 220 
 treatment, diet during, 215 
 hookworms expelled in, 223 
 ova absent after, 166 
 ova present after, 166 
 patient to remain in bed dur- 
 ing, 215 
 repetition of, 221 
 solvents to be avoided in, 214 
 time for giving, 215 
 Time for finding larvae after evacu- 
 ation, 170 
 for giving thymol treatment, 215 
 required in microscopic examina- 
 tion. 161 
 Tissues, symptoms on part of cer- 
 tain, 135 
 Tobacco, chewing, as remedy for 
 
 dirt eating, 147 
 Toe itch, hookworm in, 79 
 Toxin caused by hookworm, 111 
 hemolytic, in hookworm disease, 
 
 106 
 symptoms of hookworm disease 
 due to, 115 
 Treatment, 207 
 anthelmintic. 230 
 before ova appear in stool, 209 
 beta-naphtol, 222 
 
 hookworms expelled in, 223 
 Blaud's pills in, 229 
 blood charts in, 229, 231 
 diagnosis by examination of stool 
 
 after, 177 
 dose of beta-naphtol in, 222 
 of eucalyptus in, 224 
 of male fern in. 223 
 of podophyllin in, 225 
 of thymol in. 212 
 eucalyptus, 224 
 favorable prognosis in proportion 
 
 to, 188 
 gain in height after, 235 
 in weight after, 235 
 
 Treatment — cont'd, 
 general, of hookworm disease, 225 
 
 important factors in, 225 
 improvement after, 229 
 male fern, 223 
 mode of administration of thymol 
 
 in, 213 
 of anemia in hookworm disease, 
 
 225 
 of ground itch, 207 
 of hookworms in intestine, 210 
 of thymol intoxication symptoms, 
 
 219 
 other drugs in hookworm, 225 
 other methods of hookworm, 222 
 podophyllin, 225 
 thymol, diet during, 215 
 hookworms expelled in, 223 
 ova absent after, 166 
 ova present after, 166 
 patient to remain in bed dur- 
 ing, 215 
 repetition of, 221 
 solvents to be avoided in, 214 
 time for giving, 215 
 Tropics, cause of greater hookworm 
 
 infection in, 75 
 Tuberculosis, hookworm disease 
 
 mistaken for, 183 
 Type, mild, of hookworm disease, 
 122 
 secondary, of anemia, 136 
 severe, of hookworm disease, 125 
 how recognized, 127 
 Types of hookworm disease, divis- 
 ions of, 130 
 
 Ulcers caused by hookworm. 111 
 Uncinaria Americana, 30 
 ova of, 65 
 as name for hookworm in Amer- 
 ica, 49 
 duodenalis as name for hookworm, 
 17 
 ova of, 65 
 Uncinariasis. See Hookworm dis- 
 ease. 
 United States, dirt eating in, 24 
 
 hookworm disease in, 24, 37 
 Urine in hookworm disease, 150 
 Uteri of hookworm, 57 
 
 V.JlSeline, effect of, on larvs, 67 
 Vegetable cells, differentiation of 
 hookworm ova from, 169 
 
 Water, drinking, as a factor in in- 
 fection, 75 
 
 effect of, on larvfs, 67, 203 
 
250 
 
 INDEX. 
 
 Water — cont'd. 
 
 skin infection by larvffi-contain- 
 ing, 45 
 
 sore, hookworm in, 79 
 Weather, infection during rainy, 92 
 Weight, gain in, after treatment, 235 
 
 Wet shoes, infection through, 92 
 Worm infection, eosinophilia pres- 
 ent in, 180 
 Worms, dirt eating cause of, 147 
 
 ZooLOGic features of hookworm, 46 
 
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