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 RC171 .J12 Plague; its cause an 
 
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PLAGUE 
 
PLAGUE 
 
 ITS CAUSE AND THE MANNER OF ITS 
 EXTENSION— ITS MENACE— ITS CONTROL AND 
 SUPPRESSION— ITS DIAGNOSIS AND TREATMENT 
 
 BY 
 
 THOMAS WRIGHT JACKSON, M.D. 
 
 MEMBER AMBHICAN RED CROSS SANITARY COMMISSION TO SERBIA, IQIS; LATBLT 
 
 CAPTAIN AND ASSISTANT SURGEON, V. S. VOLUNTEERS; LATELY LECTURER ON 
 
 TROPICAL DISEASES, JEFFERSON MEDICAL COLLEGE; MEMBER OF MANILA 
 
 MEDICAL SOCIETY AND PHILIPPINE ISLANDS MEDICAL ASSOCIATION; 
 
 AUTHOR OF A TEXT BOOK ON TROPICAL MEDICINE; DIRECTOR, 
 
 DEPARTMENT OF SANITATION AND EPIDEMIOLOGY 
 
 FOR H. E. MULFORD COMPANY 
 
 WITH BACTERIOLOGIC OBSERVATIONS 
 
 BY 
 
 DR. OTTO SCHOBL 
 
 BUREAU OF SCIENCE, MANILA 
 
 ILLUSTRATED 
 
 PRESS OF 
 
 J B. LIPPINCOTT COMPANY 
 
COPYBIGHT, 1916 
 BY THOMAS WRIGHT JACKSON, M.D. 
 
THIS BOOK IS DEDICATED BY THE AUTHOR TO 
 
 DR. ALDO CASTELLANI 
 
 REGIUS PROFESSOR OF TROPICAL DISEASES, 
 TOSriVEBSITY OF NAPLES. EMINENT IN MEDICAL 
 RESEARCH, MY FRIEND, COLLEAGUE AND COM- 
 RADE DURING STRENUOUS DAYS IN SERBIA 
 
CONTENTS 
 
 PAGE 
 
 Introduction 11 
 
 CHAPTER I 
 
 Its History and Its Extension 19 
 
 History of Plague — The Widespread Dissemination of Plague 
 in Recent Years — The Appearance of Plague in Porto Rico, 
 New Orleans and Manila. 
 
 CHAPTER II 
 
 The Cause and the Menace of Plague 28 
 
 Causation of the Disease and its Mode of Conveyance — 
 Types of Plague — Chronic Plague and Immunity in Rats 
 — Flea Conveyance of Plague Bacilli — The Stability of Viru- 
 lence of Plague Bacilli — Summary of Facts Concerning the 
 Cause and Manner of Extension of Plague. 
 
 CHAPTER III 
 
 Its Control and Suppression 40 
 
 Plague Prevention by Extermination of Rats — General Use- 
 lessness of the Rat and Its Enormous Destructiveness, with 
 Details of Trapping and Other Extermination Methods — The 
 Manila Epidemic, 1912-1914 — The First Cases — Unusual 
 Character of Plague Cases at Quarantine — Clinical Descrip- 
 tion of Two Cases at Quarantine — Inauguration of the Manila 
 Epidemic — Directed to Take Charge of Plague Suppression in 
 Manila — Plague Fighting Organization — Method of Rat Proof- 
 ing and Rat Destruction — Correspondence Between Dr. Jack- 
 son and Dr. Heiser, Director of Public Health — Observations 
 on Fleas and Their Habits — Conditions of Habitations iii 
 Manila Favoring Rat Multiplication and Spread of Plague — 
 Comparative Statistics on Methods of Catching Rats — The 
 Natural Enemies of the Flea — Zoologic Classification of Rats — 
 A Collection of Notes Concerning Rat Runs, Rat Nests, Multi- 
 
 5 
 
6 CONTENTS 
 
 pie House Infections and Other Data — Sample of Detailed 
 Orders Issued Regarding Rat Extermination — Method of Pro- 
 cedure of Collecting and Forwarding Rats Suspected of Plague 
 Infection to Laboratory — Memoranda in Plague Cases — Letter 
 of Warning and Appeal for Cooperation — Bacteriologic Ob- 
 servations made During the Manila Plague Epidemic, By Dr. 
 Otto Schobl — Notes Concerning the Bubonic Plague in Hong 
 Kong, by Dr. David Roberg. 
 
 CHAPTER IV 
 
 Its Diagnosis and Treatment 165 
 
 Biologic Diagnosis — Necessity for Trained Bacteriologist — 
 Bacteriologic Procedure — Non-Biologic Diagnosis — Sympto- 
 matology — Pathologic Considerations — Treatment, Conditions 
 and Prognosis — Serum Treatment — Symptomatic Treatment 
 — Statistical Studies in Mortality — Dosage and Technique of 
 Serum Administration — Prophylactic Serum and Anaphylaxis 
 — Plague Vaccines. 
 
ILLUSTRATIONS 
 
 PAGE 
 
 Rat-Proof STRtrcTUEE 48 
 
 Cleaning and Rat-Peoofing in Basement 69 
 
 Bamboo Hotjse Supports not Sealed with Cement 86 
 
 Materials Must be Moved About in the Search for Rats 93 
 
 A Rat-Infested Plague Interior 95 
 
 Progressive Post-mortem Changes in Rat Cadavers 105 
 
 Plague House 116 
 
 Bamboo House Supports Sealed with Cement 119 
 
 View of House Where Infected Rats Were Found 120 
 
 Animal House 144 
 
PLAGUE 
 
 ITS CAUSE AND THE MANNER OF 
 ITS EXTENSION — ITS MENACE — ITS 
 CONTROL AND SUPPRESSION 
 — ITS DIAGNOSIS AND TREATMENT 
 
INTRODUCTION 
 
 The question of the need for new books upon 
 medical topics must ever remain undecided, by gen- 
 eral agreement, in the medical profession. 
 
 There is no such thing in medical literature as 
 an insistent demand from the profession for new 
 volumes upon old topics. 
 
 Authors need not hope, therefore, to create the 
 impression that they are meeting long-felt though 
 unexpressed wants of medical readers in launching 
 new books. 
 
 On the other hand, the creator of a new volume 
 upon an old subject should seek justification for 
 literary paternity in the progressive changes in the 
 status of our knowledge of disease, its causes, pre- 
 vention, and cure. Such changes are admittedly 
 going on with a certain degree of constancy and at 
 such a rate of frequency that new presentations of 
 old themes are both justified and desirable from 
 time to time. 
 
 With this idea in mind and with the desire to 
 
 present, in useful and practical form, a work which 
 
 shall contain at least some unhackneyed material 
 
 11 
 
12 PLAGUE 
 
 and which shall represent modern studies and a 
 record of actual control work done in this justly- 
 dreaded disease, the following pages are submitted to 
 the medical profession and to sanitarians generally. 
 
 With a profound respect for the laboratory 
 worker and his work and with a profound convic- 
 tion that to him belongs the greater measure of 
 credit for real accomplisliment in connection with 
 plague up to the present time, I desire to insist that 
 the true utility of knowledge gained within labo- 
 ratory walls lies in its intelligent application in the 
 outer world and that ofttimes this application must 
 be made by men who are themselves without ex- 
 tended laboratory training. An appreciation of 
 principles — with an intelligent ability to accept, to 
 appropriate, to apply and, most of all, to refrain 
 from entering without due preparation the domain 
 of the laboratory worker — is an indispensable req- 
 uisite in the equipment of the practical sanitarian, 
 upon whom must fall the responsibilities of success 
 or failure in combating the disease we are now to 
 consider. 
 
 During the past fourteen years it has been my 
 privilege to observe two epidemics of plague in the 
 PhilijDpine Islands. Some of these observations were 
 
INTRODUCTION 13 
 
 made in the capacity of a military medical officer, but 
 my later observations, upon which this report and 
 study are chiefly based, were made from the view- 
 point of a civil health officer. At different times I 
 have been called upon to deal with the disease both 
 as sanitary officer and clinician, and from October, 
 1912, to July, 1914, 1 had charge of all plague sup- 
 pressive measures in Manila. In 1914 I was also 
 in charge, as acting chief, of the San Lazaro Hos- 
 pitals Division of the Bureau of Health, Manila, 
 where all cases of plague are brought, either for 
 treatment or autopsy. 
 
 As some of the material which I have collected 
 for text-book articles during the past eight years 
 bears directly upon the present discussion and pres- 
 entation, I have ventured to quote from it, some- 
 times without rephrasing, such parts as are accurate 
 at the present time. I am also quoting freely from 
 the records and from the experiences of my pred- 
 ecessors and colleagues in the work in Manila. 
 
 It should be understood that the pathology of 
 the disease has been practically omitted from con- 
 sideration as out of place in an epidemiologic in- 
 vestigation and report. The pathologic side of the 
 work during the Manila epidemic of 1912-1914 was 
 
14 PLAGUE 
 
 covered in a masterly manner by Dr. B. C. Crowell 
 and his associates at the Medical School of the Uni- 
 versity of the Philippines, and I have no doubt that 
 the record of the work done and studies made will 
 appear in appropriate form in due time and will 
 hereafter be referred to as among the most valuable 
 pathologic studies ever made during a plague 
 epidemic, on account of their accuracy and com- 
 pleteness. 
 
 I have included, as of great value and directly 
 related to the epidemiologic phase of this study, 
 reports of some of the bacteriologic work done in 
 connection with this epidemic at the Bureau of 
 Science, Manila, by Dr. Otto Schobl. I am sure 
 that the value of his studies as reported in part here, 
 with his permission, will be apparent to every care- 
 ful reader. I am greatly indebted to him for his 
 permission to make use of this portion of his studies. 
 Having been in daily touch with Dr. Schobl during 
 the year and a half of the continuance of this 
 epidemic, I can appreciate to the fullest extent the 
 painstaking and accurate character of his work and 
 findings, of which the part here presented is by no 
 means the greatest. 
 
 I am quite aware of the fact that there are those 
 
INTRODUCTION 15 
 
 who view with some question the practicabihty of 
 controning plague by the measures apphed in 
 Manila, as recited here; but American plague 
 workers are likely to meet this unbelief by pointing 
 to the accomplished fact, in San Francisco, in Hono- 
 lulu, in Porto Rico, as well as in Manila; and be- 
 fore long, as we confidently expect, in New Orleans. 
 These exponents of the school which contends 
 that plague epidemics are little affected by rat-ex- 
 cluding, rat-destroying and rat-proofing efforts, be- 
 lieve that the waning and disappearance of epidemic 
 plague in a given place depend in chief part upon 
 the exhaustion of susceptible material among the 
 rodent population. However appealing this argu- 
 ment may be, it is impossible for its exponents to 
 duplicate American results with equal results in the 
 cities of China, India, Java and elsewhere, where 
 governmental control and adequate financial ability 
 to carry out campaigns have been lacking, from 
 one cause or another. Wherever our methods have 
 been followed, at home and in the insular possessions 
 of the United States, we have terminated human 
 epidemics of plague and have apparently put an 
 end to rat plague in comparatively short cam- 
 paigns. So long as this discrepancy in results con- 
 
16 PLAGUE 
 
 tinues we shall favor the American plan. Whe 
 we review the work and results of Blue and his fe 
 lows of the United States Health Service and tl 
 officers of the Bui-eau of Health of the Pliilippir 
 Islands, we find little reason for us to favor a chan^ 
 to the expectant plan of waiting for an epidemic 1 
 run its course. 
 
 While speaking of the Philippine Islands, tl 
 admirable work of Strong in ]Manila, covering yea: 
 of study of the immunity problem, and his dange 
 ous and higlily valuable work as a member of tl 
 Commission wliich studied the Manchurian epidem 
 of pneumonic plague in 1911, must be mentione( 
 
 Some years ago I called attention to the fai 
 that few, if any, American cities were prepared 1 
 meet an outbreak of plague with an adequate supp] 
 of antipest serum and that the preparation of ant 
 plague serum was a neglected or overlooked branc 
 of serum manufacture in the United States. Sin( 
 that time, in the midst of a plague epidemic i 
 IManila, where, for a time, the supply of locally pr^ 
 pared (Bureau of Science) serum threatened 1 
 become exhausted, I looked into the possibilities ( 
 getting a supply elsewhere and found that, to do s 
 in anything like a reasonable length of time, wi 
 
INTRODUCTION 17 
 
 impossible. Fortunately the threatened serum 
 famine did not occur, the local supply in Manila 
 proving adequate, although for a few weeks we were 
 obliged to make use of a stock of Japanese serum 
 which had been on hand for several years. Since 
 the warning of some years ago, at which time the 
 plague danger was an anticipated one, bubonic 
 plague has actually appeared in the United States 
 (New Orleans), the cases being sufficiently numer- 
 ous to cause grave concern and to call forth the 
 utmost repressive efforts of the authorities. The 
 possibility of plague appearance in the coast cities 
 of the United States, at any time, cannot be disre- 
 garded and provision for the treatment of human 
 cases, as well as repressive (antirat) measures, is 
 imperative. Antiplague serum is not producible 
 upon a few hours' notice, nor is it manufactured in 
 the United States. In view of present war con- 
 ditions the difficulty of securing serum from over- 
 seas sources is greatly increased, so that we are well- 
 nigh compelled to depend upon home-produced 
 serum. In view of the uselessness of drug treat- 
 ment it is plainly the duty of national, state and 
 municipal authorities to keep on hand a reasonable 
 
 supply of antipest serum to meet any outbreak. 
 2 
 
18 PLAGUE 
 
 Manufacturers of biological products realize that 
 the preparations for producing, storing and market- 
 ing antiplague serum are expensive and that the 
 maintenance of immunized animals and the employ- 
 ment of expert serologists call for expenditures 
 which are unlikely to be recovered from any demand 
 for serum and that, moreover, the government is 
 doing and will do all that lies within its power to 
 make the serum unnecessary, by excluding plague. 
 These are not encouraging conditions to lead Amer- 
 ican serum producers to add antiplague serum to 
 the list of their products. If, under these adverse 
 conditions, any producer of biologic products shall 
 undertake to produce and maintain an adequate 
 supply of antiplague serum, he will merit credit for 
 a truly philanthropic service and will deserve the 
 support of governments, national, state and munici- 
 pal, as well as that of the medical profession. 
 
CHAPTER I 
 
 ITS HISTORY AND ITS EXTENSION 
 
 In plague there exists the most intimate relation- 
 ship between cause and prevention. We will there- 
 fore set forth here, as briefly and concisely as their 
 importance will permit, the principal facts related 
 to the causation of the disease. Without an under- 
 standing of this relationship there can be no rational 
 preventive treatment. 
 
 These facts constitute one of the interesting 
 stories of modern medicine : the story of the arrange- 
 ment and interpretation of certain apparently un- 
 related facts, some of them long known to men, in 
 the clear light of modern method; the story of the 
 application of analysis, synthesis, logic and experi- 
 ment, all leading to the creation of an understand- 
 ing which permits us to battle successfully with 
 pestis bubonica, one of the most ancient of human 
 plagues. 
 
 History. — This disease has an historic interest, 
 most engaging and fascinating, which one finds it 
 difficult to pass over with mere mention. 
 
 I venture to recall, therefore, that plague almost 
 
 19 
 
20 PLAGUE 
 
 certainly dates back to the pre-Christian era, the 
 earlier record naturally being lacking in sufficient 
 accuracy of description to enable us to identify the 
 recorded epidemics, definitely and positively, with 
 true bubonic plague. 
 
 An epidemic of the second century B.C., as de- 
 scribed, seems to have been one of true plague, while 
 the pandemic which began in Egypt in the sixth 
 century a.d., thence extending to Constantinople, 
 Europe and the British Isles, was certainly the dis- 
 ease known in modern times as the plague. This 
 pandemic, beginning as the plague of Justinian, was 
 probably followed by the continuous presence of the 
 disease in Europe, marked by many local outbreaks 
 and periods of quiescence and extending down 
 through the centuries to the period of the Crusades. 
 In the eleventh and twelfth centuries the returning 
 Crusaders spread the plague widely through 
 Europe, which country it ravished from the eleventh 
 to the fourteenth centuries, reaching its climax of 
 intensity in the " Black Death " of Europe of the 
 Middle Ages. The disease thereafter continued to 
 devastate Europe, the great population centres, 
 Paris and London, suffering especially from its 
 visitations and its more or less constant presence. 
 
ITS^HISTORY AND ITS EXTENSION 21 
 
 The Great Plague of London, the last important 
 epidemic of the disease in that metropolis, began in 
 1664 and lasted five years. With less than half a 
 million of inhabitants it is estimated that London 
 gave one of every six or seven of her citizens to the 
 Black Death during the first year of the epidemic. 
 Then followed a remarkable disappearance of the 
 disease from Western Europe. The eighteenth 
 century was marked by few epidemic appearances 
 of plague. 
 
 At the end of the first half of the nineteenth 
 century it had practically disappeared from Egypt 
 and from European and Asiatic Turkey, formerly 
 its favorite haunts. In interior Asia it has probably 
 existed for centuries, the non-emigrating character 
 of the people limiting and confining its devastations. 
 
 To these centres and to the commercial invasion 
 of China, we must probably trace the beginning of 
 the present pandemic of plague, which exists to-day, 
 a menace to the civilized and uncivilized world. In 
 the days of the Crusades a religious invasion of the 
 infected centres caused the disease to spread 
 throughout Christendom, while in the present day a 
 commercial invasion has caused it to spread com- 
 pletely around the world. 
 
22 PLAGUE 
 
 That this is a truth and not a fanciful statement 
 is shown by the appearance of plague in the follow- 
 ing countries since 1894, when it spread from in- 
 terior China. In every case it has followed those 
 sanitary lines of least resistance, the paths of 
 commerce. 
 
 Extension. — To the eastward, from China, it 
 spread to Japan, the Philippines, Australia, the 
 Hawaiian Islands, Alaska, California, Mexico, 
 Peru and the western coast of South America. To 
 the westward, it invaded India, Mauritius, Egypt, 
 Suez ports. Eastern, Central and South Africa, 
 Mediterranean ports. Great Britain ( Scotland) , the 
 West Indies and Brazil. In the last twenty years 
 plague has caused millions of deaths, and, during a 
 single week in April, 1907, it destroyed more than 
 75,000 lives in India, a number about equal to the 
 deaths of a year in London during the Great Plague 
 of 1665. In contrast with India the rest of the 
 world has suffered little during the present world- 
 epidemic, but this loss, while relatively small, is 
 enormous when translated into lives and dollars. 
 The figures for India are simply huge. 
 
 Mortality. — The official lists of deaths in India 
 for the last twenty years include some in which the 
 
ITS HISTORY AND ITS EXTENSION 23 
 
 number of reported deaths per year exceeded one 
 million, and it has been estimated that the actual 
 number of persons dead from the plague during 
 this period approximates 8,000,000. 
 
 It is gratifying to note a marked decrease in the 
 total mortality in the reports of the last few years, 
 but so long as the annual death list, year after year, 
 was measured by hundreds of thousands, rather 
 than thousands, the situation could not be consid- 
 ered as anything but grave. 
 
 Widespread Dissemination in Recent Years. 
 — Without going into statistics deeply we may con- 
 sider also the list of countries, states and islands 
 from which plague cases have been reported 
 officially during the last few years. 
 
 My purpose is to invite attention to the con- 
 tinued existence of various plague foci, any one of 
 which might serve to extend the infection further, 
 were governmental quarantine and public health 
 supervision relaxed. 
 
 During August, September, October, Novem- 
 ber and December, 1909, plague cases occurred in 
 India, Mauritius, China, Japan, Egypt, Turkey, 
 Russia, British East Africa, the Azores, Venezuela, 
 
24 PLAGUE 
 
 Ecuador, Peru, Chili, California (two cases), and 
 the Hawaiian Islands. 
 
 During the first half of 1910 no very marked 
 variation in the distribution of plague occurred, 
 cases being reported from practically all of the 
 foreign countries just named. 
 
 A year later the situation, so far as the distribu- 
 tion of plague cases is concerned, was not greatly 
 changed, as may be seen from the following tabu- 
 lation, which I have abstracted from the British 
 Medical Journal of September 16, 1911. 
 
 India. — Deaths from plague in India during the 
 first six months, 604,634. Most prevalent (1) 
 United Provinces, 281,317; (2) Punjab, 171,084; 
 (3) Bengal, 58,515; (4) Bombay Presidency, 
 28,109. Deaths in July, not included above, 8990. 
 
 Hong Kong. — April 24 to August 21, 255 cases, 
 194 deaths. 
 
 China. — Since January 1, 1911, plague was re- 
 ported in varying intensity in (provinces and 
 towns) Manchuria, Peking, Tien-tsin, Chefo, Shan- 
 tung, Shanghai, Amoy, Foochow, Swatow, Canton, 
 Pakhoi and Laichow. 
 
 Indo-China. — At Saigon, in March and April, 
 1911, many cases reported. April 17 to May 7, 
 
ITS HISTORY AND ITS EXTENSION 25 
 
 56 cases; 17 deaths. May 22 to May 28, 37 cases; 
 12 deaths. 
 
 Siam. — In Bangkok plague was more severe 
 during 1911 than in any previous year. March 15 
 to April 15, 33 cases and 29 deaths. 
 
 Java and Sumatra. — In Java, May 25 to June 3, 
 105 cases and 62 deaths (one province). In 
 Sumatra plague was present, no statistics. 
 
 Straits Settlements. — A few cases, mostly im- 
 ported, reported in 1911. 
 
 Japan. — ^A few cases at Kobe in 1911. In For- 
 mosa, from April 2 to April 15, 31 cases; 24 deaths. 
 
 Egypt. — ^Plague reported from Port Said, 
 Suakin (on board ship), Cairo and Alexandria; 
 also from 11 provinces. The province of Kena had 
 a severe outbreak, May 5 to May 31, 51 cases and 
 49 deaths. 
 
 Persia. — Several cases reported from ports on 
 the Persian Gulf. ' 
 
 Turkey in Asia. — A few cases at Muscat, Basra 
 and at Port of Jeddah. 
 
 British East Africa. — Kismayu and Port 
 Florence reported a few cases in April, 1911. 
 
 Mauritius. — January 1 to April 11, 110 cases 
 and 70 deaths. 
 
26 PLAGUE 
 
 Portuguese East Africa. — Plague was reported 
 present at Nahoria in May, 1911. 
 
 Russia. — In the Kirgis Steppe in the Astrakan 
 Government in January, 50 cases ; 30 deaths. 
 
 South America. — Plague prevailed during 1911 
 in Peru, Ecuador, Brazil, Chile and Venezuela. No 
 severe outbreak except in Peru, where from Feb- 
 ruary to May many cases occurred and died. At 
 Libertad, in March, were reported 60 cases and 
 23 deaths. 
 
 Appearance of Plague in Porto Rico, New 
 Orleans AND Manila. — The developments of 1912, 
 which most concern us, were the appearance of 
 human plague and the discovery of plague-infected 
 rats in Porto Rico, Cuba, and the Philippines, and 
 the discovery of infected rats in New Orleans. Thus 
 the Atlantic cities of the United States were for 
 the first time seriously threatened, and the menace 
 of the pestilence at home loomed up on our horizon 
 with sufficient prominence to excite public concern. 
 Our protectors and guardians of the United States 
 Public Health Sei^ice, to whose watchfulness we 
 must credit our prolonged escape from the plague, 
 are carrying out all the protective measures at their 
 command with the utmost activity. 
 
ITS HISTORY AND ITS EXTENSION 27 
 
 At the present time we find Porto Rico freed 
 from the disease. New Orleans has undergone and 
 is still undergoing treatment which may be expected, 
 most confidently, to clear it of both human and 
 animal plague. 
 
 Of Manila and the work there, much will be 
 found in the following pages, but as both rat plague 
 and human plague have been absent for more than 
 a year we may fairly look upon the epidemic as 
 ended. After so long an interval as this any re- 
 appearance of plague may fairly be viewed as a 
 new epidemic, although it is not humanly possible 
 to say that rat plague has entirely and permanently 
 disappeared from the city of Manila, as yet. 
 
CHAPTER II 
 
 THE CAUSE AND THE MENACE OF PLAGUE 
 
 The foregoing facts are quite sufficient to make 
 us realize both the possibihty and the danger of a 
 world- epidemic ; a danger which has existed for 
 some years and which recently has been especially 
 menacing to the United States. 
 
 Causation of the Disease. — ^Plague is an acute 
 infectious epizootic disease, caused solely by Bacillus 
 pestiSj a bacterial organism. The disease is com- 
 mon to man and to a number of the lower animals 
 and fowls. 
 
 Prominent among the animals susceptible to 
 the disease is the rat, and from this animal, through 
 the intermediation of the flea, bj^ far the most cases 
 of human plague arise. In California the ground 
 squirrel (Citellus heecheyi) , a rodent closely related 
 to the marmots of Asia, plays a similar role. Of 
 the Asian marmots, the tarbagan, a large rodent, 
 also commonly suffers from subacute chronic 
 plague, which is transmissible to man as an acute 
 disease by the fleas which the animal harbors. 
 
 Its Conveyance. — Although conveyance of 
 
 28 
 
THE CAUSE AND MENACE OF PLAGUE 29 
 
 plague through rats by contact alone — that is to say 
 without the medium of the flea — is denied by mod- 
 ern experimenters, it is perhaps wiser and safer 
 to consider the disease infectious, inoculable and 
 contagious in the common medical meaning of these 
 terms. While it is usually conveyed to man by 
 the flea, it may be acquired by the inhalation of 
 plague bacilli and, according to some authorities, 
 by ingesting or swallowing the bacilli. 
 
 When infection takes place through the diges- 
 tive tract, or in other words, by the ingestion of 
 bacilli, either the flesh of plague-infected animals 
 or fowls, or food superficially contaminated with 
 plague bacilli by rats, cockroaches or other carriers, 
 serves as the medium. 
 
 Speaking practically, the possibility of infection 
 through ingestion is nearly negligible. Indeed, the 
 conclusion of Simpson in regard to this possibility 
 has been disputed and denied. However, the recent 
 occurrence of plague in a cat in Manila, in my own 
 experience, observed with me and carefully worked 
 out by Dr. Otto Schobl, points strongly to the pos- 
 sibihty of ingestion plague, the cat in this case ap- 
 parently having acquired plague from eating rats 
 dead from plague. 
 
30 PLAGUE 
 
 A full account of this case appears in the bac- 
 teriologic observations of Dr. Schobl and in my 
 recital of the history of the Manila epidemic. 
 
 Types of Plague. — Plague in man may be of 
 several types and these are designated by names 
 descriptive of the symptoms or of the regions of 
 the body most affected. Thus we have bubonic, 
 septicemic and pneumonic types. As both mild 
 and virulent cases occur, we also use terms descrip- 
 tive of the severity and course of the cases. Thus 
 we describe certain cases as ambulant, abortive, 
 larval and fulminant. In the rat the evidences of 
 plague are less striking in life than they are at the 
 post-mortem table. Indeed plague-stricken rats, 
 either naturally or artificially (experimentally) in- 
 fected, often show very slight evidences of disease 
 before death. Chronic plague in rats and a relative 
 immunity to inoculation in certain wild rats are 
 fairly well recognized phenomena. 
 
 Flea Conveyance of Plague Bacilli. — Both 
 male and female fleas convey plague, but the exact 
 method of carrying the plague bacilli from diseased 
 rats to man, while fairly well determined, is of such 
 recent decision as to leave room for further experi- 
 mentation. At present it is believed that the flea 
 
THE CAUSE AND MENACE OF PLAGUE 31 
 
 deposits plague bacilli, at the time of biting, upon 
 the skin, by ejecting the contents of its rectum 
 and by regurgitation of its stomach contents. At 
 least the flea is known to perform these acts at the 
 time of biting, and the rubbing or scratching of the 
 flea bite with the hand may easily introduce the 
 bacilli into the skin at this spot/ 
 
 The possibility that the flea introduces the 
 plague bacilli upon his mandibles, or the skin-pierc- 
 ing armament with which he is provided, is also to 
 be considered. However, the following facts sup- 
 port the first proposition. It has been experi- 
 mentally shown that the average capacity of a flea's 
 stomach is about one-half of a cubic millimetre and 
 that thousands of plague bacilli may be ingested 
 by the flea during the biting of a plague-diseased 
 rat; that the plague bacilli multiply enormously 
 and for many days in the flea's stomach and that 
 
 * Acknowledgment is hereby made to the Contributors to 
 " The Rat and Its Relation to Public Health " by various 
 authors, prepared by direction of the Surgeon-General, P. H. 
 and M. H. S., for numerous facts utilized in the preparation 
 of this article. The particular contributors whose valuable 
 chapters have been drawn upon for information are D. E. 
 Lantz, C. W. McCoy, D. H. Currie, Carrol Fox, Rupert Blue, 
 W. C. Rucker, R. H. Creel, M. J. Rosenau, V. C. Heiser, 
 W. C. Hobdy, and J. W. Kerr. 
 
32 PLAGUE 
 
 the bacilli are found only in the insect's digestive 
 tract ; that plague bacilli are regurgitated from the 
 stomach and are voided from the rectum with the 
 digested blood. 
 
 It has also been proved that almost all varieties 
 of rat fleas, under favorable circumstances, will bite 
 man and that the most common human flea {Puleoc 
 irritans) is frequently found upon rats, the flea, 
 generally speaking, being much less particular in 
 his choice of hosts and in his permanence of resi- 
 dence than most insects and ectoparasites in general. 
 
 Of the rat fleas, Pulex pallidus (Loemopsylla 
 cheopis) is common under various names in India, 
 the Phihppines, Austraha, Italy, Brazil and in 
 tropical countries generally. It bites both rat and 
 man. Ceratophyllus fasciatus, the common rat flea 
 of Great Britain and the United States, also bites 
 both rat and man. In North America and else- 
 where certain other fleas of the genus Ceratophyllus 
 have been found upon ground squirrels, cats, rats, 
 sparrows and in chicken yards. 
 
 Dog fleas and cat fleas (genus Ctenocephalus) 
 also infest rats, and fleas of other genera are found 
 upon mice, rats and ground squirrels rather indis- 
 criminately. 
 
THE CAUSE AND MENACE OF PLAGUE S3 
 
 The significance of these facts in connection 
 with prevention of plague is apparent and it is 
 plain that our warfare against fleas must be made 
 upon all fleas and not upon a single variety. In 
 this connection the possibilities of the conveyance 
 of plague bacilli by other suctorial parasites and by 
 insects which are not parasites, must be borne in 
 mind. 
 
 Thus the bed-bug, the louse, the tick and the 
 mosquito must be suspected as possible intermedi- 
 aries and the fly and the cockroach as possible food 
 contaminators. Indeed, laboratory experiments 
 have already incriminated bed-bugs, flies and lice 
 as potential vectors of plague bacilli. 
 
 Experiment and observation have demonstrated, 
 however, that above all other parasites and in- 
 sects, the flea is most likely to convey the plague 
 germ from rat to man, by reason of his frequent 
 excursions from rat-host to human-host, his taste 
 for blood from either host, his enormous activity 
 and his ability to jump. After a searching inquiry 
 into the plague question the Indian Plague Com- 
 mission came to the conclusion that contagion plays 
 a very minor part in the spread of the disease, less 
 than three per cent of human cases being so acquired. 
 
34 PLAGUE 
 
 This commission also decided that infection is 
 conveyed from rat to rat and from rat to man 
 solely through the agency of fleas. While these 
 conclusions are probably true — and therefore of the 
 utmost importance from the standpoint of prac- 
 tical prevention — I should question whether the 
 other possibilities, however remote, are entirely 
 negligible. 
 
 Seasonal conditions may affect the course of 
 an epidemic in various ways, (a) By effect upon 
 flea prevalence, cold weather greatly lessening the 
 number of insects, (b) By effect upon rats, cold 
 weather and rains either driving them from over- 
 ground to underground, or vice versa, or from their 
 principal avenues of travel in cities (the sewers), 
 into houses and buildings, (c) By effect upon 
 the plague germ. Bacillus pestis. The resistance of 
 this organism is very variable, sunlight and drying 
 being its greatest enemies, while darkness and damp- 
 ness are its chief allies. So far as temperature is 
 concerned, the plague bacillus is not likely to be seri- 
 ously affected by natural temperatures, as it is 
 not destroyed by heat below 150 degrees Fahren- 
 
THE CAUSE AND MENACE OF PLAGUE 35 
 
 heit, nor by cold measured by zero Fahrenheit, which 
 means that it survives freezing, generally speaking. 
 
 It is probable that the periods of greatest sea- 
 sonal prevalence of plague will be found to corre- 
 spond generally with increased prevalence of rat 
 fleas. During the periods when rat fleas are absent 
 or least prevalent, the disease is perpetuated in the 
 form of chi'onic (subacute) rat plague in a small 
 number of the rodents. The India Plague Com- 
 mission made and verified this observation. 
 
 Cholera epidemics often abate spontaneously 
 and this is believed to be due in part to attenuations 
 of virulence and changes in the cholera organism 
 which may be demonstrated in the laboratory. We 
 can hardly hope for such spontaneous abatements in 
 plague epidemics, as it has been found difficult to 
 attenuate or to intensify cultures of plague bacilli 
 permanently in laboratory experiments with 
 animals. If it is true that plague epidemics are 
 often marked by a preponderance of mild cases 
 in the early days and a gradual subsidence of in- 
 tensity of the cases as the epidemics wane, we prob- 
 ably will have to look to the susceptibility of our 
 
36 PLAGUE 
 
 patients for our explanation of this phenomenon, 
 rather than to variations in the virulence of the 
 plague bacilli. If plague bacilli continue to be 
 distributed to susceptible people the disease should 
 continue with a general stability of virulence. 
 Stability of Yirulexce of B. Pestis. — ^Ac- 
 cording to Strong, stabihty of virulence is a marked 
 characteristic of B. pestis, it having been shown by 
 him that it is difficult to increase the virulence of a 
 very virulent strain or to intensify'' an attenuated 
 one in laboratory animals, working with monkeys, 
 rats and guinea-pigs.^ If his observations are cor- 
 rect (and they seem to correspond with the find- 
 ings of other observers), the oft-recorded occur- 
 rence of a preponderance of mild cases of plague 
 in the early days of an epidemic and the gradual 
 subsidence in intensity of the disease as the epidemic 
 approaches its close will have to be explained upon 
 other grounds than those of variability of virulence 
 by attenuation of virulent strains alone. While he 
 
 ^"Studies in Plague Immunity," R. P. Strong, Philippines 
 Journal of Science, June 1907, No. 3. Frequent reference has 
 been made to these studies in the preparation of this article, 
 for which acknowledgment is hereby made. 
 
THE CAUSE AND MENACE OF PLAGUE 37 
 
 admits that B. pestis may become attenuated under 
 certain conditions many times during the course 
 of an epidemic, it may also regain its virulence, 
 he contends, under other conditions. 
 
 With these facts concerning the cause and the 
 manner of extension of plague and its menace be- 
 fore us, we are in position to approach the problem 
 of prevention intelligently, and in the case of plague 
 prevention is preeminently preferable to cure, as 
 well as decidedly more practicable. 
 
 I think we may be permitted here to sum up 
 the problem of plague prevention thus: Without 
 fleas, without rats, or without human plague cases, 
 there can be no extension of plague, practically 
 speaking. 
 
 Therefore the destruction of both rats and fleas, 
 the isolation of human plague cases, and the ex- 
 clusion from them of all suctorial parasites and in- 
 sects, will provide practical security for mankind 
 generally. 
 
 A word concerning pneumonic plague may be 
 permissible. This form of plague occasionally oc- 
 curs in epidemics of great fatality, as, for example, 
 the epidemic in Manchuria, North China, u few 
 years ago. 
 
38 PLAGUE 
 
 The mystery of this outbreak was largely dis- 
 pelled by the work of the Americans, Strong, 
 Teague and Barber, of the Bureau of Science of 
 Manila. 
 
 The occurrence of secondary pneumonia in 
 bubonic or septicsemic plague is rather common and 
 it is likely that such secondary plague pnemnonias 
 are the starting points of epidemics of pneumonic 
 plague, i.e. J of cases of primary plague pneumonia, 
 the point of infection being in the respiratory organs 
 and the infection being acquired through the inspira- 
 tion of plague bacilli. 
 
 The principal prerequisites seem to be an ex- 
 tremely moist atmosphere under confined conditions 
 and a low temperature ; conditions most unfavorable 
 to evaporation and ventilation. Under these con- 
 ditions the pneumonic patient sprays plague bacilli 
 into the air while coughing and droplet infection 
 follows. 
 
 It is therefore apparent that epidemic pneu- 
 monic plague is controllable by sanitary and hy- 
 gienic measures and, furthermore, that in the ab- 
 sence of original cases of bubonic and septicemic 
 
THE CAUSE AND MENACE OF PLAGUE 39 
 
 plague, with secondary plague pneumonias which 
 give rise to primary plague pneumonia in the man- 
 ner explained, respiratory plague in epidemic forai 
 will not occur. 
 
 There is no evidence pointing to the conveyance 
 of respiratory plague by insects or other carriers. 
 
CHAPTER III 
 
 ITS CONTROL AND SUPPRESSION 
 
 Plague Prevention. — At present the most 
 promising and the most rationally based phase of 
 plague control is that of prevention. The reason 
 for this is plainly apparent. If the facts in the 
 case are as stated and if the conclusions of the 
 Plague Commissioners and students of epidemi- 
 ology the world over are correct, to eradicate plague 
 we need only to control its carriers. 
 
 To exterminate the rat (and perhaps the mar- 
 mot and ground squirrel), to prevent the transpor- 
 tation of rats or of infected rat fleas in ships, trains, 
 clothing, merchandise and upon the bodies of men 
 and animals from the numerous foci or plague 
 centres of the world to non-infected localities, is a 
 beautiful plan indeed. 
 
 Restricted to single communities, even where 
 the intelligence, patriotism, effort and wealth of 
 the whole people are enlisted, the undertaking is 
 formidable, with obstacles to its execution, and dis- 
 couragement must often be expected. Extended 
 in its application to the whole plague-infected world 
 
 40 
 
ITS CONTROL AND SUPPRESSION 41 
 
 it becomes an undertaking seemingly impossible of 
 accomplishment. 
 
 Yet we are encouraged to face the situation by 
 a glance at what has been accomplished. The 
 United States, perhaps, presents the highest ex- 
 amples of achievement in the cases of San Fran- 
 cisco and Manila. The work in San Francisco is 
 too recent and has been too well published to require 
 detailed review here. A successful campaign against 
 rats in 1907 practically terminated an epidemic of 
 considerable proportions well within a year. Be- 
 hind this movement, however, were the powerful 
 machinery of the Federal Government, money in 
 generous amount and a considerably aroused pub- 
 lic, resentful of the mismanagement of the 1903 
 epidemic, whereby, through pure fear of financial 
 loss to commercial interests and by a disgi-aceful 
 suppression of the truth, California was made, per- 
 manently perhaps, one of the world's plague centres. 
 
 It has been estimated that the rat population of 
 the world is equal to the human population, and this 
 estimate does not appear to be unreasonable when 
 one considers as indices the destruction of the ro- 
 dents in cities by the hundreds of thousands, upon 
 
42 PLAGUE 
 
 single farais by the thousand, and the wonderful 
 procreative powers of the rat. 
 
 Economic Importance of Rat Destruction. 
 — It is certain that the economic importance of rat 
 destiniction upon groimds other than those purely 
 sanitary must be impressed upon the pubhc wher- 
 ever a rat campaign is to be carried on. 
 
 The absolute inutility of the rat, its enormous 
 destructiveness to crops, to merchandise in ware- 
 houses and in transit, to poultry, eggs, fruits and 
 vegetables, to buildings and furniture, and its in- 
 cendiary habits causing annual fire losses of con- 
 siderable magnitude, must be emphasized in season 
 and out of season. Such items as the value of the 
 grain consumed by a single rat per year, as estimated 
 by the experts of the Agricultural Department, are 
 convincing arguments in the case. At a daily con- 
 sumption of two ounces, the ration for a full-gi'own 
 rat, this grain value varies from sixty cents per 
 year, for wheat, to two dollars per year, for oat- 
 meal, for each rat subsisted. Similar data in great 
 variety, relating to direct and indirect losses, are 
 available for the purpose of making impressive the 
 economic need for rat destruction. 
 
 Accumulated experience from various countries 
 and cities shows plainly that there is no single 
 
ITS CONTROL AND SUPPRESSION 43 
 
 method of rat destruction to be depended upon to 
 the exclusion of all others and it also shows that 
 without governmental direction and supervision, 
 backed by ample authority and the ability and will- 
 ingness to expend considerable money, neither 
 single nor combined methods will be successful. 
 Moreover in the countries where special effort is 
 most needed there is often distrust on the part of 
 the natives, religious prejudice against the destruc- 
 tion of animal life and frequently open opposition 
 to the authorities in their efforts to destroy rats. 
 The same superstitions and religious beliefs which 
 prevent the killing of venomous snakes in India, 
 at the annual cost of thousands of human lives, 
 operate against most measures of rat destruction 
 proposed by the Government. 
 
 Extermination Methods. — The plans and 
 weapons of warfare against rats include the use 
 of poisons ; traps ; starvation ; rat-proof construction 
 of buildings, wharves, bakeries, stables, granaries, 
 etc.; the introduction of diseases among the rat 
 population by bacterial viruses and the conservation 
 of the natural enemies of the rat, such as the cat, 
 the dog, the ferret, the mongoose, and certain wild 
 animals and birds of the woods and fields. 
 
44 PLAGUE 
 
 Among the most widely used and most eiFec- 
 tive poisons is arsenous acid boiled with rice, or 
 mixed with cheese or cornmeal in the form of a 
 paste, or placed upon sweets and fruits. 
 
 Crude phosphorus is chiefly used in similar 
 pastes. When mixed with glucose its inflammable 
 properties are said to be lost. Its inflammabihty is, 
 of course, a serious obstacle to its general use. 
 
 Strychnine, owing to its bitter taste, is of little 
 value in poisoning rats, and when used is best com- 
 bined with glucose and one per cent, of cyanide of 
 potassium. Soaked v/heat, bread or similar food 
 is then treated with this mixture and placed where 
 rats may eat it. It is said to be eaten readily by 
 ground squirrels with fatal effect. It is, however, 
 expensive and apt to be taken by domestic fowls. 
 Most rat poisons have the disadvantage of being 
 dangerous to human life and must be used with 
 caution wherever children and ignorant native per- 
 sons are about. 
 
 Trapping. — Trapping has been found to be a 
 very effective means of rat destruction in cities. 
 (See later pages for relative efficiency of traps.) 
 Rat traps are of several varieties and are con- 
 structed upon various principles. It is sometimes 
 
ITS CONTROL AND SUPPRESSION 45 
 
 desirable to catch the rats alive and uninjured, and 
 for this purpose barrel traps, wire cage traps and 
 similar devices are placed in the rat highways. These 
 highways are readily discovered in the cities. Con- 
 siderable care must be taken to overcome the natural 
 caution of the rat, and this includes judgment in 
 the use of attractive bait, the concealing and smok- 
 ing of traps after handling and perhaps the use 
 of some scent, such as the oil of anise, of which rats 
 seem to be fond. As a general rule bait should 
 differ from the food naturally supplied by the 
 locality. For example, about granaries and stables 
 fresh animal food should be used for bait, while 
 about slaughter houses, meat-markets, fish-markets 
 and similar places, where animal ofFal is abundant, 
 the rat should be tempted with vegetable bait. 
 
 Where the circumstances will permit, and this 
 is apt to be so for ground-squirrel destruction, the 
 burrows may be filled with some asphyxiating or 
 poisonous gas. In this manner whole families of 
 rodents, and their fleas as well, are destroyed. 
 
 The system is not often applicable in houses, but 
 aboard ships it is found most effective, the holds of 
 ships being flooded with sulphur dioxide, developed 
 by burning sulphur in a special furnace provided 
 
46 PLAGUE 
 
 with a pumping and piping system for delivering 
 the gas at distant parts of the ship. In empty ships' 
 holds and elsewhere the simple burning of sulphur 
 in open vessels effects the same results, provided 
 sufficient sulphur and a sufficient nmnber of vessels 
 be used and further provided that the generation 
 and confining of gas be sufficiently prolonged. In 
 San Francisco harbor, where for more than a year 
 nine vessels were disinfected per day, this method 
 was adopted as more effective, speedy and econom- 
 ical than any other system. It has the disadvan- 
 tage, in the case of laden ships, of affording some 
 danger of fire. 
 
 Carbon bisulphide has been extensively used in 
 California in the burrows of ground squirrels. Its 
 fumes, being heavier than air, penetrate the bur- 
 rows and promptly poison or asphyxiate all living 
 animals and fleas. Absorbent material of some kind 
 is saturated with the liquid and placed in the en- 
 trance of the burrow, which is then quickly sealed to 
 confine the gas. 
 
 It will be seen that, in common with other 
 methods of rat destruction, fumigation has a limited 
 application and a number of serious objections. It 
 is particularly useful aboard ships. 
 
ITS CONTROL AND SUPPRESSION 47 
 
 The method should never be employed by mi- 
 skilled persons or those unacquainted with the 
 dangers to human life from noxious or asphyxiating 
 gases. 
 
 Starving Rats. — The subjects of the starva- 
 tion of rats and rat-proof construction may be con- 
 sidered together. 
 
 Just as the pig in the Philippine Islands and 
 elsewhere in the Orient must give place as a scav- 
 enger of human excreta to modern and decent 
 methods of waste disposal, so must the rat, a gar- 
 bage scavenger the world over, give place to sys- 
 tematic garbage collection and removal, with tem- 
 porary storage of garbage in covered metal cans 
 (rat proof). 
 
 Incidentally it may be mentioned that the effect 
 of such measures upon the prevalence of flies and 
 the transmission of disease by these insects will be 
 very great and very beneficial to the public health. 
 
 Food must be kept from rats and rats must be 
 kept from the food. Perhaps the greatest resorts 
 of rats are the places where cattle are fed, where 
 grain is stored and where animals are killed. 
 Slaughter houses, markets, grocery stores, restau- 
 rants, bakeries, wharves and warehouses must be 
 
48 PLAGUE 
 
 regulated by ordinances duly enforced. Much can 
 be done with screens of heavy iron wire with a mesh 
 of less than one inch. 
 
 When concrete and metal have displaced wood 
 and plaster as construction materials; when plank 
 sidewalks and refuse piles are no more and when the 
 catch basins of sewers have been made rat-proof 
 the subsistence problem for the rat will be greatly 
 increased in difficulty, and starvation should then 
 begin to lessen the rat population, at least in the 
 cities. 
 
 Rat-proofing. — Municipal authorities should 
 take up the matter of rat-proof construction for new 
 buildings and the rat-proofing of old ones by ap- 
 proved alterations. In Manila, Hong Kong and 
 elsewhere these methods are receiving attention and 
 encouraging reports are recorded, more particularly 
 with regard to the disappearance of plague in dis- 
 tricts so treated than in the disappearance of rats. 
 This is most important, for if the rat and his fleas 
 are excluded from houses and therefore from in- 
 timate association with man ( an apparently feasible 
 matter through the rat-proof construction of build- 
 ings), protection against human plague is in great 
 measure accomplished. 
 
ITS CONTROL AND SUPPRESSION 49 
 
 In Manila the disappearance and continued ab- 
 sence of human plague in previously infected local- 
 ities goes hand in hand with the introduction of 
 systematic rat-proofing in sections where cases of 
 human plague occur. 
 
 These measures were first instituted in 1906 and 
 plague disappeared from Manila in the same year 
 and did not reappear until 1912. 
 
 From 1900 to 1905, $15,000 was paid in rat 
 bounties and $325,000 was paid for salaries, wages 
 and expenses in rat catching, with little appreciable 
 effect upon the number of rats and without causing 
 the plague to entirely disappear. It must be ad- 
 mitted, however, that practical control of the dis- 
 ease was attained during this period. 
 
 Rat-proofing of dwelling houses is less expensive 
 than perpetual wholesale rat destruction and is a 
 perfectly effective measure against human plague. 
 In the suppression of the San Francisco epidemic 
 in 1907 rat-proofing was also extensively resorted to. 
 
 The expense of rat-proofing has been generally 
 considered as prohibitive, but if the work be con- 
 fined at first to the vicinity of infected centres and 
 if it be carried on subsequent to rat-destruction in 
 corresponding areas the expense need not always be 
 
50 PLAGUE 
 
 prohibitive — at least in American governed cities. 
 The Manila plan of plotting the city into "plague- 
 infected " areas corresponding with the capture of 
 plague-diseased rats and systematically working 
 within geographic boundaries in which rat plague 
 exists or is likely to spread, as determined by rat 
 captures and examinations of the rats for signs of 
 plague, has proved to be a good plan. 
 
 To prevent the transportation of rats in ships, 
 trains and merchandise is an undertaking of diffi- 
 culty as well as of importance. In the case of ves- 
 sels it involves an understanding of the manner by 
 which rats gain ingress to the ship and the ways of 
 preventing them from entering. Few facts are bet- 
 ter known, perhaps, than the fact that all ships har- 
 bor rats, but, except to the initiated, the extent to 
 which some ships are infested is by no means under- 
 stood. I have made voyages upon steamships, which 
 upon alternate trips carried forage for animals in 
 the holds, when the conditions were, to say the least, 
 uncomfortable. To have one's state-room taken 
 possession of by rats, his clothing carried away, or 
 to awake with a rat in his berth are unpleasant, but 
 not uncommon, experiences. I personally know of 
 a woman, prostrated with sea-sickness, who was 
 
ITS CONTROL AND SUPPRESSION 51 
 
 obliged to remain in her berth and see four large 
 rats disport themselves about her room, and in 
 another case, on the same ship, a rat jumped from 
 the washstand into the berth of a sleeping woman, 
 running across her exposed face and arm. 
 
 In travelling upon small dirty steamers in the 
 Orient I have often slept on deck, quite as much to 
 avoid the rats and vermin in the state-rooms as for 
 better ventilation. In a certain ship in which I 
 travelled some of the ship's officers amused them- 
 selves by shooting rats with an air-rifle in the lower 
 decks, quietly hiding themselves in dimly-lighted 
 places and shooting the rats as they crossed the 
 hghter spaces. 
 
 In many ships the rat population far exceeds 
 the human population. In San Francisco 310 rats 
 were destroyed by a single fumigation on a vessel 
 of only 260 tons burden. In Bombay 1300 rats 
 were destroyed at one time upon a single ship and 
 in London 1700 were secured at one fumigation. 
 
 The ease with which rats adapt themselves to 
 new environment is shown by the fact that they live, 
 when permitted to do so, in cold storage and re- 
 frigerating rooms where they grow heavy coats of 
 fur for protection against the cold. 
 
52 PLAGUE 
 
 They gain ingress to ships in three principal 
 ways: (1) By coming overside upon gang-planks, 
 wharf stringers, etc. (2) By passing along the 
 lines by which the ship is made fast to the dock, 
 through hawse holes, the rat being an expert rope 
 walker. (3) By coming aboard in the cargo. 
 
 By the latter method rats are often brought 
 aboard by whole families, their fleas included. Many 
 styles of packages such as barrels, bales, crated 
 goods, grain in sacks and matting in rolls present 
 the rat with abundant opportunity to take pas- 
 sage and it is probably thus, as stowaways, that 
 rats go to sea in the largest number. Plainly, then, 
 the placing of rat-funnels upon all lines from ship 
 to wharf, the use of special fenders, the raising of 
 gang-planks and even anchorage in the stream will 
 not prevent rats from getting aboard ships unless 
 cargo disinfection be practised before loading the 
 vessel. The ship itself should be fumigated every 
 three months if possible. 
 
 Rats are doubtless carried in considerable num- 
 bers upon railway cars, both freight and passenger. 
 
 While riding in a street car in Manila in 1908 
 I saw a rat run along the window ledge, to the 
 mingled fright and amusement of the passengers. 
 
ITS CONTROL AND SUPPRESSION 53 
 
 The same principles which apply in the case of 
 ships apply to cars and trains as well. Grain cars 
 in particular should receive especial attention. 
 
 Rat Destruction by the Spread of Rat Dis- 
 eases. — The proposal to destroy rats by wholesale, 
 by spreading epizootic diseases among them, through 
 feeding them bacterial virus, has received much at- 
 tention in the last ten years. In 1900 Danysz iso- 
 lated a bacillus from field mice suffering an epi- 
 demic disease communicable to rats, and great hopes 
 were entertained that by means of this method de- 
 cided reductions in the rat population would result. 
 Indeed the results in Cape Town, South Africa, in 
 1901, and in Odessa, Russia, in 1902, seemed to 
 justify the hope to some extent and certain observers 
 still believe the method to be effective. Experience 
 with the Danysz and other organisms has shown, 
 however, that introduced epidemic diseases do not 
 destroy rats in sufficient number to do much good 
 and that nearly all the viruses experimented with 
 are more or less unreliable. 
 
 Most of the organisms are apparently related 
 to the colon, typhoid or hog-cholera groups. The 
 mouse-typhoid bacillus {B. typhi murium) was 
 originally isolated by Loeffler in 1899. The para- 
 
54 PLAGUE 
 
 typhoid bacillus and Gartner's B. enteritidis cot- 
 respond closely with the Danysz organism and can 
 scarcely be separated culturally. In rodents they 
 produce enteritis, sometimes hemorrhagic in char- 
 acter, and they are by no means to be regarded as 
 harmless for man, as originally supposed. In Japan, 
 in particular, serious and fatal cases of diarrhoeal 
 disease have followed the accidental eating by man 
 of food treated by these bacterial poisons. 
 
 On account of the natural resistance of rats to 
 diseases of bacterial causation (plague being the 
 most notable exception to this rule), and the clin- 
 ical fact that no sufficient death rate among rodents 
 is produced by feeding them upon bacterial viruses, 
 as well as on account of the dangers to man just 
 mentioned, this method of rat destruction is not in 
 favor at present. 
 
 Poisoning rats and ground squirrels by chem- 
 ical poisons seems to be a preferable method, at 
 least equally effective and without most of the dis- 
 advantages of uncertainty and danger which attach 
 to the bacterial viruses. 
 
 Rat Destruction by Domestic Animals. — 
 Concerning the utility of such domestic animals as 
 are natural enemies of the rat, in the warfare against 
 
ITS CONTROL AND SUPPRESSION 55 
 
 the offending rodents, there is considerable differ- 
 ence of opinion, based upon varying experiences. 
 I leave out of consideration all but the cat and dog. 
 
 It will be found that wherever cats and dogs 
 are well housed (indoors) and well fed they are 
 apt to be fat, lazy and inefficient. House cats of 
 this class will catch mice but will often leave rats 
 alone, but half -wild cats, obliged to forage for their 
 own subsistence, are often excellent rat-catchers. 
 Small, active dogs, particularly of the terrier breeds, 
 will often keep houses practically free from rats 
 and upon farms they are especially valuable, par- 
 ticularly if the construction of buildings is such as 
 to permit them to get beneath the floors. The em- 
 ployment of these animals will necessarily be con- 
 fined to individuals for the freeing of individual 
 premises from rats. 
 
 A fact to be borne in mind is one abeady cited, 
 viz. : that cats and dogs sometimes harbor the same 
 fleas as the rat. Infected rat-fleas often leave dead 
 rats for other animals and, all things considered, 
 there are many other objections to the intimate 
 house dog and house cat which find comfortable 
 resting places impartially upon the beds of adults 
 or the cribs of babies and children. 
 
56 PLAGUE 
 
 Furthermore, my personal observations have 
 been such as to cause me to place small reliance in 
 the value of the ordinary dogs and cats found about 
 habitations wherein the construction is favorable to 
 rat-harboring. 
 
 Summary of Prevention for the Com- 
 munity. — Before passing to the consideration of 
 other matters I would smn up the measures of pre- 
 ventive treatment for the community. There must 
 be (1) Active warfare against rats and other 
 plague-affected rodents and their fleas; (2) Modi- 
 fied quarantine — detention or disinfection applied 
 to persons, goods and animals; (3) Disinfection of 
 cargoes shipped from infected ports; (4) Isolation 
 of the sick and proper disposal of the dead; (5) In- 
 ternational notification between governments of the 
 occurrence of plague within their respective terri- 
 tories; (6) Lastly, — but we might say fii'st in im- 
 portance, — the early recognition of the presence 
 of plague and the rapid diagnosis in individual 
 cases, both of which are dependent upon laboratory 
 workers. 
 
 All of these measures must be fostered, directed 
 and aided in every possible way by competent au- 
 thority (national if possible), whose ofiicers must 
 
ITS CONTROL AND SUPPRESSION 57 
 
 be men of great moral courage and of unselfish pur- 
 pose. Behind all of this must be generous financial 
 support. 
 
 I can best emphasize the importance of the ob- 
 servance of the principles I have laid down by in- 
 troducing personal experiences in the conduct of 
 the antiplague campaign in Manila during 1912, 
 
 1913 and 1914. 
 
 I therefore present here the following account 
 of the epidemic, the campaign of suppression and 
 the various lessons learned. 
 
 It should not be difficult for the reader to make 
 applications of the principles already set forth and 
 to confirm by the reported facts the assertion that 
 methods based upon these principles are effective. 
 
 If repetitions of any of the foregoing principles 
 occur it is hoped that, when taken in connection with 
 concrete applications cited, they will not appear as 
 redundant. 
 
 The Manila Epidemic of 1912 to 1914. — The 
 chronologic facts concerning the development and 
 extension of plague in Manila in 1912, 1913 and 
 
 1914 are as follows: 
 
 The disease made its reappearance in Manila, 
 after an absence of six years for the human disease 
 
58 PLAGUE 
 
 and five years for rodent plague, two verified human 
 cases having been recorded in June, 1912. 
 
 Preceding the appearance of the first Manila 
 cases there occurred upon incoming ships a number 
 of cases of plague during the Spring of 1912, de- 
 tected at quarantine. Although there is no con- 
 clusive evidence which connects these imported cases, 
 originating in Hong Kong, China, with the epi- 
 demic which broke out in Manila a few months 
 later, the fact of their occurrence and recognition is 
 interesting enough for us to consider before taking 
 up the study of the Manila epidemic. Concerning 
 these imported cases Dr. Victor G. Heiser, then 
 Director of Health for the Philippines, wrote as 
 follows in the Philippine Journal of Science, in 
 February, 1914. 
 
 Unusual Character of Plague at Quarantine. — 
 It is perhaps worthy of note that, prior to the appearance 
 of plague in Manila a number of cases of the disease were 
 found on incoming steamers. For instance, on April 6, 
 1912, a death was reported on the steamship Zafiro, which 
 had arrived the day previous from Hongkong and had 
 been in the harbor for twenty-four hours at the time of 
 the death. At the medical inspection of the vessel, which 
 was made the day previous, no illness was detected. An 
 investigation showed that the victim had been on deck on 
 the night of April 5, 1912, in apparently good health. 
 The next morning, at 6 o'clock, he was found dead in his 
 
ITS CONTROL AND SUPPRESSION 59 
 
 bunk. The necropsy and subsequent biological findings 
 reported by Dr. R. P. Strong of the Bureau of Science 
 showed that death was due to pneumonic plague. 
 
 On April 7, 1912, the steamer Loongsang arrived in 
 Manila from Hongkong, and the captain reported that a 
 death had occurred the day previous in a Chinese member 
 of the crew. Upon investigation of this case, the captain 
 stated that the man was apparently in good health, but 
 that while hauling on a rope he fell over in an apparent 
 faint and was placed in a chair and in the course of a few 
 hours expired. The necropsy and animal inoculations 
 showed that he had died of plague and probably of the 
 pneumonic variety. 
 
 Beginning April 7, 1912, the temperature of all mem- 
 bers of the crew and of the passengers that arrived in 
 vessels from foreign ports was taken with a view to de- 
 tecting any possible cases of plague. 
 
 On the arrival of the steamship Taisang from Amoy 
 at the Mariveles Quarantine Station at about 6.30 a.m. 
 on April 30, 1912, the entire personnel was carefully ex- 
 amined and found free from sickness of a suspicious nature 
 and from elevations of temperature. Seventy-three per- 
 sons were detained to serve a quarantine detention of 
 seven days. On the evening of April 30, a Chinese pas- 
 senger, aged fifty-one years, was found to have a tem- 
 perature of 39° C. with a pulse of 100. He was placed in 
 the hospital, but protested vehemently that he was not 
 sick. He was carefully watched from the first ; there was 
 a slight cough ; physical examination of the chest revealed 
 a few rales; smears made of the sputum and stained for 
 plague bacilli were negative. On the fifth day, the fever 
 still persisted, but the patient stated that he did not feel 
 ill and demanded to be released from the hospital. On 
 
60 PLAGUE 
 
 this day, the expectoration was blood-stained, but no sus- 
 picious organisms could be found in the smears nor could 
 any physical signs of pneumonia be detected. Further- . 
 more, there were no palpable glands. On the morning of 
 the seventh day, the temperature and pulse dropped and 
 the general condition was distinctly worse. The patient 
 now admitted that he felt ill. Several hours later, he 
 flinched when pressure was made in the right axilla. 
 Lymphatic enlargement was now made out, and by the 
 evening of the seventh day the bubo in the axilla had in- 
 creased markedly in size, the swelling approximating 3 
 by 7 centimetres. Glands now became palpable in other 
 portions of the body, particularly in the cervical region, 
 and a few hours later there were inguinal and femoral 
 buboes. The patient became rapidly worse, and died at 
 7 o'clock on the morning of the eighth day of his illness. 
 At the necropsy, the glands of the right axilla and those 
 of the right side of the neck were found enlarged; the 
 other lymphatic glands were also enlarged, but to a lesser 
 degree. There was consolidation of the lower lobe of the 
 right lung, and the spleen was about twice its normal size. 
 In brief, the necropsy findings of a typical case of sep- 
 ticsemic plague were present. Smears from the spleen and 
 the right axillary gland showed immense numbers of 
 bipolar-staining organisms. Cidtures made from fresh 
 pieces of tissues and later inoculated into animals gave 
 positive results for plague. 
 
 Beginning of the Manila Epidemic. — Pro- 
 ceeding with the Manila epidemic inaugurated with 
 the two cases referred to as recorded in June, 1912, 
 we find that the total number of cases recorded 
 
ITS CONTROL AND SUPPRESSION 61 
 
 from the time of the outbreak in 1912 until the last 
 case in 1914 was 90. (This includes none of the 
 imported cases from China which developed en 
 route to Manila from Chinese ports.) 
 
 Of these 90 human cases, 76 were fatal and 
 autopsies were performed in all instances. Four- 
 teen persons recovered. The number of cases of 
 animal plague up to July, 1914, was 53. This 
 refers only to laboratory-proven cases of rat plague. 
 As a matter of fact, hundreds of dead rats, almost 
 certainly plague rats, were found in the course of 
 rat-proofing operations. 
 
 Although the period covered by this epidemic 
 approximates two years, it must not be supposed 
 that the progress and extension of the epidemic was 
 an uninterrupted or unobstructed one. 
 
 On the contrary, such extension as occurred was 
 made in spite of the most active suppressive effort, 
 and it is beheved that this effort brought about a 
 creditable result, as indicated by the accompanying 
 record. 
 
 When one considers the favorable conditions 
 for the natural spread of plague, both in Manila 
 and throughout the Philippine Islands, and realizes 
 the interposed difficulties and obstructions, natural 
 
62 PLAGUE 
 
 and unnatural, geographic, human and domestic, 
 which confront us at every turn of the path to 
 correction, removal and reformation, our success 
 in checking the spread of plague appears as a real 
 achievement, especially when contrasted with the 
 results of effort during the same period in a British 
 city of similar size but a few days' sail from Manila, 
 where the cases were numbered by thousands and 
 where the infection still persists. 
 
 First Manila Cases. — The first case of plague 
 (June 12, 1912) occurred in a resident of Tondo, 
 920 Calle Antonio Rivera, and in the light of sub- 
 sequent developments it may perhaps be grouped 
 with the October cases traced to the Manila Railway 
 Company's freight station and yard, as 920 Calle 
 Antonio Rivera is but a stone's throw from the 
 Manila Railway property. The connection, how- 
 ever, is not clear, and, on the other hand, it is not 
 wholly inconceivable that the rat epidemic and hu- 
 man plague cases at the railway station in October 
 may have been secondary to this July case. Such 
 speculation is fruitless, however, so far as establish- 
 ing facts is concerned. 
 
 The second case of human plague occurred 13 
 days later, June 25, in a resident of a district some- 
 
ITS CONTROL AND SUPPRESSION 63 
 
 what removed from the first case, but in the same 
 general section of the city. 
 
 Then came a lull of more than a month, until 
 August 4, during which time no case of plague 
 occurred; or at least none was reported. 
 
 August brought forth five cases on the fourth, 
 eighth, fifteenth, and twenty-first days of the month, 
 in residents of the Quiapo and Binondo districts. 
 
 These cases were unrelated to the preceding ones 
 so far as could be ascertained. 
 
 Another lull of a month, until September 24, 
 now occurred without a reported case of human 
 plague. During this time, however, the first cases 
 of rat plague were discovered, one on August 30 
 and two on September 6, all of them in the Quiapo 
 district. 
 
 From this time (September 24) on, however, 
 human cases occurred at intervals of a few days 
 until Christmas Day, 1912, the longest plague-free 
 period being one week; the number of cases by 
 calendar months being distributed as follows : Sep- 
 tember, 3 cases; October, 22 cases; November, 12 
 cases; and December, 6 cases. 
 
 Geographic Grouping. — Not until October 21 
 was there any apparent geographic grouping of 
 
64 PLAGUE 
 
 cases indicating a well localized infected centre. 
 Upon this date there began the outbreak of plague 
 among the employees of the Manila Railway Com- 
 pany, laborers at the freight station and yard of 
 the company. This freight station and yard is lo- 
 cated between Calle Azcarraga, Calle Dagupan and 
 Calle Antonio Rivera. The outbreak totalled 17 
 human cases, all fatal, and extended into Novem- 
 ber. Indeed, the last case traced to this focus oc- 
 curred on December 7, 1912. 
 
 During the present epidemic of plague in Manila 
 this focus was the only one to which a larger number 
 of cases than five could be traced, and in all the 
 other instances where multiple cases were traced to 
 an infected centre, the foci were all single buildings. 
 
 The locations giving rise to multiple infections 
 and the number of cases of plague developing at 
 each address, with months of incidence, are as fol- 
 lows: Calle San Fernando (804-814), November, 
 1912, 4 cases; Calle Teodoro Alonzo (518) , Novem- 
 ber and December, 1912, 2 cases; Calle Cabildo 
 (Intramuros), November and December, 1912, 2 
 cases; Calle Comercio (1028), February, 1913, 2 
 cases; Calle Sande (1364), April, 1913, 5 cases; 
 Calle Juan Luna (1226), May, 1913, 2 cases. 
 
ITS CONTROL AND SUPPRESSION 65 
 
 Returning to the Manila Railway outbreak, it 
 is necessary to state that a well-defined epidemic 
 among rats preceded this outbreak, resulting in the 
 death of a large number of rodents (undoubtedly 
 from rat plague) . This epidemic was not reported 
 by the railroad company until the outbreak of hu- 
 man plague had begun. It was then too late to 
 identify plague in the dead and mummified rats 
 found under floors, platforms and elsewhere, but 
 the fact that large numbers of rats had recently 
 died here was established by the unanimous testi- 
 mony of the employees at the freight station and 
 the finding of rat cadavers. 
 
 As stated, the human outbreak here occurred 
 upon October 21, and fifteen cases developed within 
 3 days. 
 
 This indicates an extensive desertion of fleas 
 from plague rat cadavers and an attack upon hu- 
 man beings, after a fasting period, on the part of 
 the fleas, of several days. The human outbreak 
 at the station and the death of a large number of 
 rats at the same place, just previous, correspond to 
 a nicety and establish to a moral certainty the con- 
 nection necessary to explain the epidemic. 
 
 After the railway epidemic of human plague, 
 
66 PLAGUE 
 
 cases continued to occur through November and 
 December, without apparent relation to each other, 
 except in the following instances, which have already- 
 been mentioned: 
 
 Four cases under one roof on Calle San Fer- 
 nando (November 12, 13, 16 and 22) ; 2 cases in 
 one house on Calle Teodoro Alonzo (November 26 
 and December 2) ; and 2 cases in the same house 
 on Calle Cabildo (Intramuros), November 23 and 
 December 11. 
 
 These multiple cases will be referred to else- 
 where. 
 
 The other cases during October, November and 
 December were apparently sporadic and unrelated, 
 either to the other human cases or to the few scat- 
 tering cases of rat plague discovered from time to 
 time. Without doubt, however, all were actually 
 related to preceding cases of rat plague, i.e.j to un- 
 discovered rat cadavers, dead from plague and 
 deserted by infected fleas. 
 
 In the following plague houses (see list of cases) 
 dead rats were actually found, although the ad- 
 vanced degree of desiccation and mummification 
 defeated the biologic determination of the cause of 
 
ITS CONTROL AND SUPPRESSION 67 
 
 death: 518 Calle Teodoro Alonzo; 973 Calle Azcar- 
 raga; 282 Estero de Binondo. 
 
 In other plague houses the recent finding of 
 dead rats was alleged by the occupants, but rather 
 too indefinitely to record positively. 
 
 A study of the maps and lists showing the local- 
 ities in which cases of rat plague had been found up 
 to this time (December 26, 1912), in connection 
 with the location of plague houses, was much less 
 suggestive than a similar study of the lists and maps 
 covering the cases of 1913. 
 
 However, the existence of concurrent rat plague 
 and human plague, in corresponding sections of 
 Manila, had been well established already by bac- 
 teriologic studies of captured rats, made at the 
 Bureau of Science. 
 
 Of nearly equal weight was the observation con- 
 cerning the two epidemics, rat and human, at the 
 Railway Station, which I have already described. 
 
 The year 1912 closed, then, with a recorded total 
 of 50 human cases and 7 verified cases of rat plague. 
 
 January, 1913, saw but a single case of human 
 plague. This occurred on January 24, just a month 
 from the last previous case, that of Christmas Day. 
 
68 PLAGUE 
 
 During this month no case of rat plague was 
 reported. 
 
 In February, 3 human cases occurred and in 
 March, 4 cases were recorded. 
 
 Early in March, 1913, cases of rat plague began 
 to occur in the Tondo district in a section lying be- 
 tween Manila Bay and the Estero de la Reina and 
 extending northward from Calle Moriones. This 
 was a new district for rat plague and as the cases 
 increased in number we were able to foresee and 
 predict the appearance of human plague in the same 
 district, which in point of congestion of population, 
 poverty of its residents and in the matter of dilapi- 
 dation of its light material houses and shacks, is 
 about the worst locality in Manila. 
 
 From March 22 to September 20, 1913, all the 
 cases of human plague, 11 in number, occurred in 
 the midst of this district. During the same period 
 25 cases of rat plague were reported from the same 
 section, and a glance at a map of this part of Tondo 
 instantly shows the relationship existing here be- 
 tween rat plague and human plague. 
 
 This relationship is additionally emphasized by 
 referring to the memoranda concerning certain over- 
 crowded houses, in the midst of the rat plague dis- 
 
3 H 
 
 £ ^ 
 
ITS CONTROL AND SUPPRESSION 69 
 
 trict, where multiple human cases occurred. (See 
 memoranda in re 1226 Calle Juan Luna and 1364 
 Calle Sande.) 
 
 The human cases in April were 5 in number, all 
 originating in the same house, and the May cases 
 numbered 4, two of which occurred in the same 
 house. 
 
 It may be explained, in passing, that two cases 
 of human plague, discovered in Malolos, 25 miles 
 from Manila, on March 23 and March 26, respec- 
 tively, were definitely traced to the same house in 
 Manila, number 12 Calle Aguila, Tondo, both pa- 
 tients having lived in the basement of this house 
 until witliin 48 hours of the development of the 
 disease. These persons were unrelated and were 
 two of a large number of people who lived in a tene- 
 ment at this address. Both patients were detected, 
 while still alive, in Malolos, where they were Hving 
 in different and widely separated houses. One of 
 the patients died in Malolos but the other one was 
 brought to Manila by train and died at San Lazaro 
 Hospital. Fortunately no infection was transferred 
 to Malolos by these two persons. In this connec- 
 tion it is interesting to note that no other cases have 
 been reported from outside of Manila, except the 
 
70 PLAGUE 
 
 small outbreak in Iloilo in the southern islands, 
 where the antiplague work was successfully directed 
 by Dr. Carroll Fox. Concerning this outbreak, 
 Dr. Heiser, then Director of Health for the Philip- 
 pines, writes as follows (Philippine Journal of 
 Science, February, 1914) ; 
 
 Plague in Iloilo. — In Iloilo, a case suspicious of 
 plague was reported on July 5, 1912, and this diagnosis 
 was subsequently confirmed by the laboratory. It oc- 
 curred in the person of a Chinaman who was reported to 
 have come from Bais, Oriental Negros, but later inves- 
 tigation showed that he had been a resident of Iloilo at 
 least since February, 1912. The next case was reported 
 August 18, and the last case, September 17, 1912. There 
 was a total of 9 cases. All of the cases were confined to 
 two houses. During July, August, September, and Oc- 
 tober, 1146 rats were caught in the vicinity of the houses 
 in which the human cases had occurred, along the water 
 front, and in the places which were regarded as suspicious, 
 but in not a single instance was an infected rat found. 
 
 Directed to Take Charge of Plague Sup- 
 pressive Measures. — Upon my arrival in Manila 
 from the United States, on October 23, 1912, I 
 received orders from the Director of Health to take 
 charge of all plague suppressive measures in Manila 
 and I remained in charge of this work continuously 
 until July 11, 1914. 
 
ITS CONTROL AND SUPPRESSION 71 
 
 Plague Fighting Organization. — The plague 
 fighting organization was composed of three Amer- 
 ican Sanitary Inspectors and from ten to fifteen 
 native Assistant Sanitary Inspectors of the Bureau 
 of Health, rat catchers and laborers of the Bureau 
 and laborers of the City of Manila supplied by the 
 Department of Sanitation and Transportation. The 
 combined force varied in numerical strength from 
 100 to 150 men and was usually divided into three 
 parties, distributed in various parts of the city ac- 
 cording to the local indications and needs from time 
 to time. 
 
 After the invasion of Tondo by rat plague we 
 made special effort to rat-proof the light material 
 houses of that section, in the course of our cleaning 
 operations, by the closure of the open ends of bam- 
 boo timbers with cement and with tin cans, in the 
 manner shown in photographs herewith. In addi- 
 tion to this, special attention was given to the repair 
 of broken cement work, and hundreds of Bureau of 
 Health orders, verbal and written, were issued to 
 owners, at my request, in the rat plague districts. 
 
 The number of houses in which bamboo timbers 
 were closed by cement or tin exceeded a thousand. 
 
 In addition to these means, the very important 
 
72 PLAGUE 
 
 matter of depopulating the insanitary basements 
 of the light material houses in squares where plague 
 has occurred was given attention, with the result 
 that hundreds of families were moved from these 
 insanitary and dangerous ground-floor rooms to 
 quarters well above ground and measurably removed 
 from the rats, which roam over the ground from 
 house to house, foraging for food under kitchens 
 and in gi'ound-floor storerooms, tiendas and eating 
 places. The fish packing factories aiFord them 
 abundant food and a number of cases of plague 
 have occurred adjacent to these fish-drying estab- 
 lishments. 
 
 Rat-proofing and Rat Destruction. — While 
 it is frankly admitted that rats may not be com- 
 pletely exterminated by poisoning and trapping, the 
 statement, so frequently repeated of late, that de- 
 structive measures really increase their number, is 
 unwarranted and unsustained by facts, at least in 
 Manila. It seems to be the common practice for 
 disbelievers in trapping and poisoning to array the 
 methods of rat-proofing and rat destruction as 
 alternative policies, whereas everyone practically 
 familiar with the work in such cities as Manila — or 
 even in the United States — ^knows that there is often 
 
ITS CONTROL AND SUPPRESSION 73 
 
 no choice permitted. Rat-proofing is highly desir- 
 able, permanent in its results, and in every respect 
 the " method of election." On the other hand, it is 
 entirely inapplicable at certain times and in certain 
 localities where poverty, lack of interest of property 
 owners, and ofttimes lack of interest and of money 
 on the part of municipalities, absolutely preclude its 
 immediate application. It is therefore unfortunate 
 that the statement, that rat poisoning and trapping 
 are ineffective, either in controlling plague or in 
 reducing the numbers of rats, is circulated. It may 
 be shown easily, by the daily records, that within a 
 few weeks after extensive rat poisoning and trap- 
 ping (with the breaking up of nests) is pursued in 
 a given locality, the rat catch drops in the most 
 decided manner. 
 
 Individual premises may be practically cleared 
 of rats by continued intelligent rat catching and 
 poisoning, and while the normal rat birth-rate may 
 keep pace with the normal rat death-rate it will not 
 keep pace with the normal death-rate plus the poi- 
 soning and trapping death-rate in any given locality, 
 provided that the poisoning and trapping, with the 
 destruction of nests, be intelligently and continu- 
 ously carried out. 
 
 Rat-proofing and rat destruction, then, should 
 
74 PLAGUE 
 
 not be contrasted as alternative procedures or 
 policies. Both are valuable and each has a proper 
 place. In communities non-infected with plague 
 and unexposed to infection it will probably be found 
 that rat-proofing, carried out in connection with the 
 repairs of old buildings and the erection of new 
 ones, will meet the requirements. On the other 
 hand, in cities exposed to plague infection or 
 already infected, rat destruction is bound to be 
 necessary for years to come. 
 
 In emergency, the removal of people from in- 
 timate relationship with rats (so far as is possible), 
 as practised recently in Tondo district, Manila, 
 will often have to take the place of rat-proofing ; and 
 rat destruction and expulsion will be found, in the 
 last analysis, to be the methods upon which success 
 or failure in fighting plague during epidemic time 
 will depend. 
 
 In this connection I quote correspondence which 
 passed between the Director of Health and myself 
 in 1913. 
 
 Upon March 22, 1913, I directed the following letter 
 to the Director of Health: 
 
 Sir : I have the honor to state that Estaban Masibac, 
 aged twenty-two, laborer, who died at 140 Perla of bu- 
 bonic plague, slept upon the ground floor of this house 
 upon a bamboo bed. All these basement dwellers in this dis- 
 
ITS CONTROL AND SUPPRESSION 75 
 
 trict now infected with rat plague are in considerable 
 danger. 
 
 The roving rats which wander over these ground sur- 
 faces from house to house come into pretty close contact 
 with these basement dwellers, and it would appear that 
 they visit the upper stories of the houses rather infre- 
 quently, unless food is stored there. Upon the ground 
 they forage upon the food dropped there by the residents 
 of the houses. 
 
 I would like to have authority to order the vacation 
 of these basement rooms which are almost invariably unfit 
 for human habitations. 
 
 I look upon this measure as an important one at this 
 threatening time and believe it should be enforced in every 
 square or block where plague rats have recently been 
 found. If this authority is granted it will be used 
 judiciously. 
 
 Very respectfully, 
 
 [Signed] T. W. Jackson, 
 
 Medical Inspector in Charge of Plague 'Suppression. 
 
 Upon March 24 I received the following letter 
 of authorization: 
 
 Sir: Confirming my verbal instructions of yesterday 
 I have to request that, in accordance with the recom- 
 mendation contained in your letter of March 22, that on 
 account of the danger of the spread of plague in the dis- 
 trict in which plague has appeared extensively, the base- 
 ment dwellers in blocks, or squares, in which plague has 
 been found, should be ordered to vacate. 
 Very respectfully, 
 
 [Signed] Victor G. Heiser, 
 
 Director of Health. 
 
76 PLAGUE 
 
 Upon November 26, 1912, five dead rats were 
 reported from the U. S. Army Comimissary Ware- 
 houses on the Pasig River near the Malecon. They 
 were found dead by workmen there and were thrown 
 into the river by the finders and thus, unfortunately, 
 examination for plague was prevented. 
 
 Upon November 27, a cat, known to have caught 
 and eaten rats recently at the same place, was re- 
 ported to be sick. I took the cat to the Bureau of 
 Science where she was observed until she died, three 
 days later. 
 
 At autopsy, typical bubonic plague (cervical) 
 was disclosed, and several guinea-pigs inoculated 
 from the spleen and bubo died from the same dis- 
 ease. A guinea-pig, inoculated from a swab intro- 
 duced into the cat's rectum, also died from plague 
 (see report of Dr. Schobl) . 
 
 Four kittens, recently born of this plague cat, 
 were observed for two weeks but showed no sign of 
 the disease. 
 
 Subsequently about 80 rats were caught at these 
 warehouses and in the vicinity, but none of them 
 showed post-mortem signs of plague. The Medical 
 Department, U. S. Army, then took up the matter 
 of rat catching on all military reservations in Manila 
 
ITS CONTROL AND SUPPRESSION 77 
 
 and in all buildings thereon, but no more oases of 
 animal plague were discovered. 
 
 Fleas and Their Habits. — In " Observations 
 Upon the Bionomics of Fleas Bearing Upon the 
 Epidemiology of Plague in Eastern Java," by 
 N. H. Swellengrebel, Ph.D., published by the gov- 
 ernment at Batavia, Dutch India, in 1913, some in- 
 teresting facts, developed by study and experimen- 
 tation, are presented. Some of these facts have a 
 bearing on the plague problem in the Philippines, 
 for it should be borne in mind that certain climatic 
 similarities and racial similarities pertain commonly 
 to the Javanese and Filipinos and their respective 
 countries. 
 
 While we are not prepared at present to make 
 general application of the Javanese findings to the 
 Philippine Islands, for lack of parallel or confirma- 
 tory studies in the Philippines, we may state some 
 of the conclusions of the Java workers with pro- 
 priety, and we may also point out similarities in the 
 construction of certain Filipino and Javanese habi- 
 tations in their relation to rat harboring. 
 
 Swellengrebel, in Java, noted the nimiber of 
 fleas per rat, dealing with Xenopsylla cheopis (the 
 commonest rat flea in Java) almost exclusively. 
 
78 PLAGUE 
 
 This flea, it will be remembered, is also the common 
 rat flea of India, the Philippines, Australia, Italy, 
 Brazil and tropical countries generally, being vari- 
 ously known as Loemopsylla cheopis, Puleoc pal- 
 lidus, P, hrasiliensis, P. philippinensis, and (in 
 Italy) P. murimis. 
 
 It would not be unreasonable, therefore, to ex- 
 pect to find at least some of his observations ap- 
 plicable to the Philippine Islands. 
 
 SweEengrebel failed to find Ctenocephalus cards 
 (dog flea), C, felis (cat flea) and Ceratophyllus 
 fasciatas (the common rat flea of the United States 
 and Europe) upon Javanese rats. In attempting 
 to determine the normal flea census he found that 
 field rats, and field rats caught indoors, as well, 
 generally carry fewer fleas than house rats and that 
 the number of fleas per house rat varies in diff'erent 
 districts from .02 per rat to 2.3 or 4 per rat and that 
 this variation is not invariably constant with the 
 presence or absence of rat plague. Concerning the 
 question whether or not a high flea census may in- 
 dicate rat plague, Swellengrebel ofl'ers the reason- 
 able opinion that there is little doubt that plague in 
 rats increases the number of fleas per rat above 
 normal and that, consequently, a sudden or marked 
 
ITS CONTROL AND SUPPRESSION 79 
 
 increase in the number of fleas per rat, without a 
 known normal cause, indicates increased rat mor- 
 tahty and probably rat plague. 
 
 As to the influence of temperature and humidity 
 on the hatching of larvae, he concludes from experi- 
 mentation that the duration of development of the 
 egg varies under various hygrometric conditions, the 
 general rule being, " the lower the humidity the 
 longer the development period." 
 
 As to the influences of temperature and humidity 
 upon the transition of larva to imago he finds that 
 if humidity diminishes, a smaller number of larvee 
 reach the adult stage; and also that a saturated 
 humidity (in artificial cultures), causing condensa- 
 tion of water in the substratum, is very fatal to 
 larvEe. He offers the thought that this, perhaps, 
 explains why only small numbers of fleas are found 
 on field rats which live in holes in rice fields which 
 are necessarily damp, especially in the rainy season. 
 
 His experiments to determine the duration of 
 life of fasting fleas were made with laboratory-bred 
 fleas which had never fed on blood and with fleas 
 which had already sucked blood. 
 
 The duration of life was variable, but of those 
 fleas already fed with blood three-quarters (^ 
 
80 PLAGUE 
 
 perished wdtliin 10 days and the remainder lived 
 from ten to twenty days, only one-tenth, however, 
 sm-viving for 13 days, if moist conditions were main- 
 tained. High temperature was determined to be an 
 unfavorable condition. 
 
 If from these findings one should attempt to 
 predicate or predict the extension of plague in 
 house rats — based on flea prevalence — and this with 
 relation to climatic conditions, we should be led to 
 the conclusion that the rainy season, with its greater 
 humidity, would be quite the most favorable time 
 of year for rat plague extension in Manila and, 
 upon the contrary, that the hot dry season through 
 its unfavorable influence upon flea breeding would 
 be the least favorable season for rat plague in 
 Manila. 
 
 The hot months of 1913 did not bear out this 
 reasoning, however, for during these months rat 
 plague was at its height. 
 
 That increased prevalence of himian plague has 
 not gone hand in hand with increased prevalence of 
 rat plague in Manila, may be explained, I feel sure, 
 by the activity of our efforts to destroy rats and to 
 remove the people from close relationship with them. 
 
 Another factor of possible explanation of the 
 
ITS CONTROL AND SUPPRESSION 81 
 
 greatest prevalence of human plague in Manila dur- 
 ing the late rainy season of 1912 (October), is the 
 fact that rats are certainly driven above ground 
 into houses and therefore into closer relationship 
 with man by heavy rainfall and the consequent 
 flooding of their subterranean homes. 
 
 It appears, therefore, that the seasonal explana- 
 tion of greater plague prevalence, rat or human, is 
 susceptible of several interpretations and I feel sure 
 that in countries like the Philippines seasonal varia- 
 tions in heat do not suffice to rid the rats of fleas dur- 
 ing any months of the year. If, then, conditions of 
 rainfall serve to drive the rats above ground and 
 indoors during certain months, it would be reason- 
 able to expect more human plague from closer re- 
 lationship of rat and man, — provided that no special 
 measures were carried out. 
 
 Such, however, is not invariably the rule, if sta- 
 tistical studies are to be taken as evidence, and so 
 we are reminded that generalizations for countries 
 of different chmates and seasons are not wholly 
 reliable. 
 
 Rat breeding, as well as flea breeding, is in- 
 fluenced by climate, but as the reproductive activity 
 of the rat is most retarded by cold weather — an 
 
 6 
 
82 PLAGUE 
 
 unknown condition in the Philippines — and as the 
 climate of Manila is fairly equable so far as heat 
 and cold are concerned, the only factor which needs 
 to be considered is that of rainfall. As already men- 
 tioned, rainfall doubtless serves to drive rats above 
 ground and so, to a certain extent, away from their 
 nests in burrows and underground. 
 
 Their well-known adaptabihty to changing con- 
 ditions, however, permits them to house themselves 
 comfortably above ground when driven out of these 
 burrows and holes. 
 
 Javan Observations. — The following conclu- 
 sions were reached by Dr. J. J. van Loghem in a 
 report upon " Some Epidemiological Facts Con- 
 cerning the Plague in Java " (published by Civil 
 Medical Service in Netherlands India-Batavia, 
 1912) : 
 
 1. In plague-infected villages, as distinguished from 
 plague-free villages, there exists a considerable mortality 
 among house rats. 
 
 2. Rats in plague houses and plague quarters have 
 repeatedly died from plague. Fresh plague rats appear 
 more often in the houses adjoining plague houses than in 
 the houses themselves. 
 
 3. The house rat exists even in the immediate vicinity 
 of man. 
 
 4j. The ordinary parasite of the house rat is Xenop- 
 
ITS CONTROL AND SUPPRESSION 83 
 
 sylla cheopis, which experimentally is known to choose 
 man as a host when starving. 
 
 5. Fresh plague rats have repeatedly been found to 
 harbor a great number of fleas. 
 
 6. Virulent plague bacilli have been demonstrated in 
 the stomachs of such fleas. 
 
 Concerning the prevention of plague by improv- 
 ing the native dwellings, the same observer says: 
 " Obviously an increase in the distance between man 
 and rat becomes an important factor as a means of 
 preventing the disease." 
 
 Conditions of Manila Habitations Favor- 
 able TO Rats and Plague. — As shown by our own 
 experiences in Manila, this end, the separation of 
 rats and men, is not obtainable by destruction of 
 rats by poison, traps and rat catchers. Rats dying 
 of plague in their nests furnish the greatest danger 
 to man. The plague problem, therefore, where rats 
 are already infected, from the stand-point of direct 
 prophylaxis, is the problem of dwellings. It was 
 from this stand-point that we attacked the problem 
 in the Tondo (Manila) campaign in 1913. 
 
 Manila Verification of Javan Observa- 
 tions. — Having in mind the experiences of the 
 plague investigators in Java during the recent epi- 
 demics there (1911-1912), we sought, from the 
 
84 PLAGUE 
 
 time the Manila outbreak occurred, to verify some 
 of the findings of the Java investigators, at least 
 with special reference to the nesting of rats in close 
 proximity to human beings and the consequent ex- 
 posure of these persons to the infected fleas which 
 desert the rats dying from plague in these nests. 
 
 Not until rat plague invaded the special district 
 of Tondo, in Manila, in March, 1913, did the oppor- 
 tunity present itself. Theretofore the Manila cases 
 had generally appeared in houses of the so-called 
 " hard material districts," where house construction 
 is entirely unlike that with which the Java workers 
 dealt. With the invasion of Tondo, however, the 
 Java and Manila conditions became similar. I 
 quote the descriptions of Javanese house construc- 
 tion from the report of Dr. J. J. Van Loghem, 
 " Some epidemiological facts concerning the plague 
 in Java," Batavia, 1912. 
 
 The Javan Village House. — In substance, he 
 says that the Java village house, as a general type, 
 is a one-storied structure with its roof sloping to 
 the front and back, i.e., with its ridge parallel with 
 the front and back aspects of the building. It is 
 not elevated above the ground by supports or pali- 
 sades and has no separate floor, the earth serving as 
 the floor. 
 
ITS CONTROL AND SUPPRESSION 85 
 
 The outer frame is of strong bamboo poles and 
 the inner frame is also constructed of bamboo. 
 These bamboo timbers are perforated at various 
 points to permit of framing with other pieces of 
 bamboo and for the entrance of pegs, etc. 
 
 The roofs of these houses are often made of tiles, 
 but at times the familiar thatched roof is seen. In 
 both cases the supports or rafters are bamboo poles. 
 The principal piece of furniture is the " bale bale," 
 or bedstead, usually made of bamboo, except in the 
 houses of the well-to-do. Small storerooms are 
 often located in the houses, and stables are some- 
 times built against them. In many cases the family 
 provisions are kept in the house and the cattle are 
 housed here as well. 
 
 Manila Light Material Houses. — If, now, 
 we turn our attention to the average Tondo 
 (Manila) light material house it will be apparent 
 that the description given for the Java village house 
 fairly describes the Tondo house, except that the 
 Philippine house is commonly elevated 2 metres 
 or more above the ground upon bamboo supports 
 (see photographs). The basement is usually en- 
 closed in a manner similar to the principal room of 
 the Java house and the basement room may fairly 
 
86 PLAGUE 
 
 be compared, structurally and in the matter of its 
 floor, with the one-story Java house. In the Manila 
 house, however, the floor of the upper room takes 
 the place of the roof of the Java house and like it 
 is supported by bamboo timbers. 
 
 Here, then, in our enclosed basement story, we 
 have a practical replica of the one-storied Java 
 house. 
 
 Here, also, the principal piece of furniture is 
 often a bamboo bed, practically identical with the 
 Java " bale bale," if we may judge from photo- 
 graphs. 
 
 In the Java houses the favorite nesting places 
 for rats were found to be the interiors of horizontal 
 bamboo pieces of the roof, house frame and bed- 
 stead. 
 
 The rat usually gains entrance by gnawing 
 through the natural partitions between the bamboo 
 sections near the outer end of the pole. Our Manila 
 photographs show both the natural open ends of 
 such timbers and the rat-gnawed perforations in the 
 partitions. 
 
 In Java, rats also nest in the thatched roofs, as 
 they occasionally do in the Philippines. 
 
 Nest Materials. — The materials utilized for 
 
■'l ! ! 1 i I . , , t .'1 * • Hi. I . , , , i , . i , , i i ( 
 
 TT 
 
 rrrrrri"' fpnrp--, rn-i--'n 
 
 ^w]]^ 
 
 |U^ I ! ! ! t ! li 
 
 i-i i ! ' I i 1 llH 
 
 xLunijiij! nm.iixi"!";]!""' mnm 
 
 BAMBOO HOUSE SUPPORTS NOT SEALED WITH CEMENT. NOTE HOLES GNAWED IN BAMBOO 
 ENDS. RATS FREQUENTLY MAKE NESTS IN THESE HOLLOW BAMBOO RAFTERS. 
 
ITS CONTROL AND SUPPRESSION 87 
 
 nests by rats in Manila and Java seem to be iden- 
 tical also. Straw, dry leaves and pieces of cotton 
 are mentioned in the Java reports. The same ma- 
 terials and additional ones will be found mentioned 
 in our reports upon nests. 
 
 The presence of food was also noted in the 
 bamboo nests in Java and we often find articles of 
 food in our Manila nests. 
 
 Dr. Kom, P. H. Service, and the writer 
 ( T. W. J. ) investigated a good many of these bam- 
 boo house-timbers and we not only found such evi- 
 dences of rats as food, rat faeces and nest materials, 
 but in one case a rat was actually driven out of a 
 bamboo nest by introducing a long thin strip of 
 wood. The evidence of similar conditions then is 
 complete. 
 
 We also duplicated the experiences of the Java 
 workers in finding dead rats inside of the bamboo 
 house timbers in close proximity to patients sick 
 (or dead) with plague (see memoranda in the case 
 of Esteban Masabik, of 140 Calle Perla, March 22, 
 1913). 
 
 Very extensive rat destruction and cleaning 
 operations, covering a large portion of the city of 
 Manila and including all sections where cases of 
 
88 PLAGUE 
 
 rat plague or human plague developed, were under- 
 taken and this work was carried on without inter- 
 ruption for about two (2) years. City laborers to 
 the number of 60 to 150 were used and the work was 
 supervised by Sanitary Inspectors Brantigan and 
 Searcy, of the Bm-eau of Health. During a part 
 of the time a flying column of 50 men, under Sani- 
 tary Inspector Hunniecutt, was detached from the 
 main party and employed at placing rat poison. 
 
 The total amount of accumulated dirt removed 
 from houses and yards approximated 5250 tons (for 
 17 months ending November 1, 1913). 
 
 Without doubt this general cleaning campaign 
 and the removal of this enormous accumulation of 
 dirt and rubbish was of great value as an antiplague 
 measure. 
 
 The rat catch will always be found to depend 
 upon several factors, viz.: the number of persons 
 employed; the number of traps and portions of 
 poison placed ; the location of the operations and the 
 length of time a given locality is trapped, poisoned 
 and cleaned. The variety of baits and poisons will 
 also affect the results. 
 
 In addition to these factors certain others are 
 found to operate in reducing the rat catch, as, for 
 
ITS CONTROL AND SUPPRESSION 89 
 
 example, weather conditions and the occurrence of 
 Sundays, hoKdays and the days just preceding and 
 following holidays. 
 
 Upon rainy days and the days just mentioned 
 the rat catch almost invariably falls oiF. 
 
 From statistics collected by me in connection 
 with this work, Dr. V. G. Heiser, then Director of 
 Health for the Philippine Islands, published the 
 following memorandum in 1914. As it is a correct 
 transcript of my records I introduce it here in its 
 entirety. 
 
 Comparative Statistics in Rat-catching Methods.^ 
 — With a view to ascertaining which type of rat trap was 
 most effective and also the average number of rats that 
 are caught by a given number of poisoned baits that are 
 set out, statistics were kept during the antirat campaign 
 in Manila. The ratio maintained in catching rats with 
 two types of traps is indicated in the following table, a 
 perusal of which will show that for the three months ended 
 June 30, 1913, there were 120,565 spring or snap traps 
 set and that for every 100 of this type of trap set there 
 were caught 6.9 rats. During the same period there were 
 4*7,075 wire cage traps set; the total number of rats 
 caught was 339 ; which gives 0.72 rat caught for each 
 hundred traps set. For the quarter ended September 30, 
 130,627 spring or snap traps were set and 9,753 rats were 
 
 1 Reprint from the Public Health Reports, Vol. 29, No. 6, 
 February 6, 1914. 
 
90 
 
 PLAGUE 
 
 caught, which gives 7.47 for each 100 traps set. During 
 this period 40,621 wire cage traps were set and 395 rats 
 were caught, which gives 0.97 rat caught for each 100 
 wire cage traps set. 
 
 
 Quarter ended June 30 
 
 Quarter ended Sept. 30 
 
 Kind of trap or poison 
 
 Number 
 set 
 
 Number 
 of rats 
 caught 
 or poi- 
 soned 
 
 Per 
 
 cent. 
 
 Number 
 set 
 
 Number 
 of rats 
 caught 
 or poi- 
 soned 
 
 Per 
 cent. 
 
 Spring or snap traps. . 
 
 Wire cage traps 
 
 Poison bacon, rice, or 
 coconuts 
 
 120,565 
 47,075 
 
 166,237 
 
 8,377 
 339 
 
 1,216 
 
 6.9 
 .72 
 
 .731 
 
 130,627 
 40,621 
 
 177,309 
 
 7,753 
 395 
 
 216 
 
 7.47 
 
 .97 
 .12 
 
 
 
 
 Quarter ended — 
 
 
 June 30 
 
 Sept. 30 
 
 Number of rats: 
 
 Caught by dogs 
 
 160 
 
 2,889 
 
 316 
 
 5 
 
 Killed with clubs and other wfif.nnns 
 
 3,818 
 
 Found dead from oth^T rnnsf 
 
 JS 
 
 
 297 
 
 
 
 
 
 
 
 
 No accurate record was kept of the number of each 
 kind of rat bait set. Only the total of all was recorded. 
 Bacon or coconut with strychnine and rice with arsenic 
 were used. For instance, for the quarter ended June 30, 
 1913, there were 166,237 poison baits set in new territory 
 and the rats found poisoned average for each 100 baits 
 0.72. During the next quarter there were 177,309 baits 
 set in territory that had been worked over, and only 216 
 rats, or 0.12 rat per 100 baits, were killed. From the 
 foregoing it appears that the rat poison ranks lowest in 
 efficiency but perhaps highest in economy. In view of the 
 
ITS CONTROL AND SUPPRESSION 91 
 
 fact that the original cost of the cage trap is many times 
 more than that of the spring trap, and the cost of main- 
 tenance is very high, it will be apparent that the spring 
 trap is by far the more economical as well as more 
 effective of the two. 
 
 Generally speaking, however, the number of rat 
 catchers engaged and the location of their operations 
 has the largest influence upon the total catch of rats. 
 For the fiscal year July 1, 1912, to June 30, 1913, 
 inclusive, the total catch was 55,101 rats (Manila 
 only) ; to December 1, 1913, 79,676. 
 
 The most natural explanation of the general 
 correspondence between the highest rat catch and 
 the highest incidence of human plague would be 
 upon grounds of greater activity in rat catching 
 effort at times of greatest plague prevalence, but 
 from the inauguration of general systematic rat 
 catching there was no cessation of effort, even dur- 
 ing the abatement of plague, and in consequence 
 this explanation does not apply strictly. 
 
 It is true, however, that whenever plague oc- 
 curred in districts theretofore free from the disease, 
 rat catching was pushed vigorously in the surround- 
 ing localities. 
 
 Making due allowance for all the factors men- 
 tioned I am impressed with the probability, amount- 
 
92 PLAGUE 
 
 ing almost to certainty, that the catch of more than 
 79,676 rats definitely aiFected and checked the 
 spread of plague in Manila in 1913; and I am of 
 the opinion that systematic and wholesale rat 
 catching, carried out in the most economical man- 
 ner possible, should be persisted in indefinitely, at 
 least imtil plague disappears, wherever the disease 
 occurs. 
 
 Efforts to prevent the spread of plague to the 
 provinces of Luzon, by way of the railways, were 
 successful and the present measures employed, 
 freight inspection, the fumigation of packages sus- 
 pected or likely to contain rats, and the similar treat- 
 ment of freight cars showing signs of rats, should 
 be continued. In a few cases these measures have 
 driven rats out of both packages and cars and the 
 animals have been killed by the sanitarians on duty 
 at the station. 
 
 The matter of water transportation was entirely 
 within the control of the authorities in charge of 
 inter-island quarantine aif airs. 
 
 Rat catching in ^lanila was systematically per- 
 formed and all rats captured were turned over to 
 the Bureau of Science for examination for plague. 
 
 When plague foci were discovered the locahties 
 
ITS CONTROL AND SUPPRESSION 93 
 
 were trapped and poisoned both circuniferentially 
 and centrally, with a view to preventing the dif- 
 fusion of infected rats throughout the city. 
 
 Rat-peoofing. — The theoretic desirability and 
 superiority of " out building " the rat, over all other 
 methods of rat suppression, is admitted. The ap- 
 parent impracticability of actually rat-proofing 
 Manila at the present time and our inabihty to 
 starve the animals out, justify the other and less 
 permanent measm^e, viz. : rat catching. However, 
 I heartily favor and ui'ge the most complete and 
 thorough-going rat-proofing of buildings actually 
 infected with human or animal plague, in all cases. 
 The building ordinances of Manila already provide 
 for rat-proof construction in all new buildings 
 erected. 
 
 With a view to cutting off the food supply of 
 the rat, more than 1100 orders upon householders, 
 to provide covered garbage cans, were served in the 
 district of Tondo alone. 
 
 The open ends of bamboo timbers in more than 
 2300 houses were closed, either by cement or tin 
 cans, during 1913. 
 
 Theatre Disinfection. — All the cinemato- 
 graphs and theatres in the city were disinfected upon 
 
94 PLAGUE 
 
 repeated occasions by spraying with petroleum and 
 cresols, with a view to destroying fleas and prevent- 
 ing plague infection. 
 
 Attempts at deception and concealment of 
 plague patients, upon the part of members of their 
 f amihes, were numerous, but with the close scrutiny 
 of death certificates and dead bodies exercised at all 
 health stations it is believed that all cases were 
 recognized. 
 
 One case of extremely careless diagnosis oc- 
 curred. A death certificate was furnished by a local 
 native doctor who certified the cause of death to be 
 " uterine hemorrhage." Suspicion arising, an 
 autopsy was ordered and a pronounced case of 
 bubonic plague was disclosed postmortem. No evi- 
 dence of uterine hemorrhage, except slight men- 
 strual signs, was found. 
 
 The destruction of infected fleas in plague 
 houses is of course the primary object of the disin- 
 fection by spraying, which is thoroughly carried out 
 in every house where a case of human plague or rat 
 plague appears. The method is a simple one and 
 consists in spraying a mixtm'e of cresols ( 2 per cent. ) 
 and kerosene (98 per cent.) over all sm'faces of the 
 house, floors, walls, underlying ground, fm^niture 
 
ITS CONTROL AND SUPPRESSION 95 
 
 and the spaces above ceilings, etc., using the mixture 
 liberally and securing a general surface distribu- 
 tion. There is no doubt of the toxicity of this mixt- 
 ui'e to all fleas and bed-bugs which it reaches, and 
 it is undoubtedly an effective measure in rendering 
 an infected house safe. All of the instances of 
 multiple house infections, where the cases recurred 
 after disinfection, in Manila, have been in houses 
 where, for one reason or another, the recommended 
 structural rat-proofing has been postponed or where 
 it has not been done. Thus, on Calle San Fernando 
 the sequence of the four cases (their progress by 
 days and in consecutive houses) is explained by the 
 travel of rats through efiicient rat runs present in 
 the walls and ceilings, rather than by the passage of 
 fleas through partition walls, from uncommunicat- 
 ing house to house. 
 
 So also at Calle Cabildo, where the superstruc- 
 ture of the house was a veritable sieve, there was a 
 series of communicating double walls. 
 
 At the house on Calle T. Alonso a similar con- 
 dition existed, but here the two cases which occurred 
 may have been synchronously infected, or nearly so, 
 previous to disinfection of the premises. 
 
 At Calle Comercio, where six days elapsed be- 
 
96 PLAGUE 
 
 tween two cases, the rooms and building were piled 
 full of merchandise, defeating immediate disinfec- 
 tion, that is, efficient disinfection, until all the mer- 
 chandise was moved and the rooms were emptied. 
 
 At 1364 Calle Sande, Tondo, where 5 cases 
 originated, the infections were undoubtedly almost 
 synchronous and no infection occurred after disin- 
 fection of the house, while at 1226 Calle Juan Luna, 
 Tondo, the two cases were plainly infected at about 
 the same time and this previous to disinfecting the 
 premises. 
 
 Guinea-pigs as Indicators of Infected 
 Houses. — The following experiment shows strik- 
 ingly the necessity for disinfecting houses where 
 hmnan or animal plague cases have occurred. 
 
 Upon December 17, 1912, Dr. O. Schobl, of the 
 Bureau of Science, and myself, placed two healthy 
 guinea-pigs, free from fleas, in a wire trap cage in 
 the house at No. 4 Calle Barraca, a few hours be- 
 fore the house was disinfected, a patient with plague 
 from this house having died within the preceding 
 twelve hours. The cage containing the guinea-pigs 
 was placed exactly where the patient had slept upon 
 the floor, as indicated by the other tenants of the 
 house. Disinfection was delayed for a few hours 
 
ITS CONTROL AND SUPPRESSION 97 
 
 and the guinea-pigs were left in the house for one 
 day. Upon December 21 one of the guinea-pigs 
 died from typical bubonic plague — anatomically and 
 bacteriologically positive — other inoculated experi- 
 mental animals also developing the disease. 
 
 Other guinea-pigs placed in plague houses on 
 Calle Cabildo and Calle San Fernando, after dis- 
 infection of the premises, failed to acquire plague. 
 
 Natural Enemies of the Flea. — It was ob- 
 served during the studies in Java that certain 
 natural enemies of fleas exist and operate against 
 their laboratory cultivation and their natural re- 
 production. 
 
 Ants of several varieties, large and small red 
 ants and small black ones, were found to be very 
 antagonistic to fleas, both in the larval and adult 
 states, destroying them actively. 
 
 Fleas in the laboratory were found to be affected 
 with mites, with a resultant high mortality among 
 the insects. The same parasites were not found 
 upon wild fleas. On account of the prevalence of 
 mites upon the laboratory fleas certain experiments 
 concerning the transmission of plague were vitiated. 
 
 The activity of ants in attacking and disposing 
 
 of rat cadavers found in our antiplague work in 
 7 
 
98 PLAGUE 
 
 IManila was frequently brought to my attention. 
 We invariably included an attack upon ants in 
 treatment of houses known to harbor, or suspected 
 of harboring, plague rats. The combination of 
 kerosene and cresols, elsewhere referred to, was 
 found to be perfectly satisfactory in the destruction 
 of ants; assuming, of course, that the necessary 
 procedure of exposing the ants, by the moving of 
 merchandise, boards or other protecting materials, 
 was performed, so that contact, by spraying the in- 
 secticide mixture, was secm-ed. 
 
 Activity of Fleas. — It was also observed dur- 
 ing the Java studies that the rat flea, while rather 
 lazy, may and does cover distances of five metres 
 and that he sometimes covers eighteen centimetres 
 at a single leap. 
 
 In addition to this, of com'se, there must be con- 
 sidered the possibility of his falling considerable 
 distances. 
 
 ZooLOGic Classification of Rats. — The mat- 
 ter of accurately, systematically and scientifically 
 cataloguing and classifying rats is one of great diffi- 
 culty and is not to be midertaken by anyone but a 
 trained naturalist. However, some of the notes we 
 have at our disposal, gathered from many som-ces. 
 
ITS CONTROL AND SUPPRESSION 99 
 
 may be set before the reader. It is extremely diffi- 
 cult to find exact correspondence of statement in 
 the various classifications offered by writers upon 
 plague and rats. 
 
 Dr. Lantz gives the following brief classification 
 in his section of the publication, " The Rat and Its 
 Relation to Public Health." 
 
 Order: Rodentia. 
 
 Family : Muridce. 
 
 Genus : Mus. 
 
 Species are many, but only three or four are cosmo- 
 politan. 
 
 Cosmopolitan species : Mus rattus — black, brown, and 
 roof {Alexandrine) rat; Mus decumanus — gray, barn, 
 wharf, sewer, and Norway rat. 
 
 Mus rattus has many varieties known through- 
 out the world and these are named according to color 
 and habitat. 
 
 In addition to the names given in Lantz's classi- 
 fication, we constantly see reference to the black 
 house rat, the brownish-gray rat (Mus Alexan- 
 drinus), the ordinary ship rat, the field rat, etc.; 
 terms descriptive of habitat and appearance being 
 very loosely applied. Little account is taken, by 
 many, of the well-known variations in the coloration 
 of rats due to climate and season and of the well- 
 
100 PLAGUE 
 
 recognized aptitude of the rat for living in-door 
 or out-door according to circumstances of food sup- 
 ply, weather, etc. The " sawah " rat of Dutch 
 India, implicated in the prevalence of plague there, 
 was formerly considered a variety of Mus decu- 
 manuSj but is now described as a field variety of 
 Mus rattus. So too, varieties of Mus decumanus 
 are frequently named according to alleged geo- 
 graphic origin, habitat, color and habits, viz. : sewer 
 rat, brown rat, Norway rat and migratory rat. 
 
 The inevitable confusion bound to arise from 
 such loose classification is obvious. 
 
 Another genus, Gunomys (Nesokia) , implicated 
 in plague, is represented in India by two species 
 and by at least one (an undetermined one) in Java, 
 some confusion existing in the matter as yet. Mem- 
 bers of this genus are described as large, rough- 
 coated rats which live both as house rats and field 
 rats. In India the Plague Commission reported 
 specimens of this genus as particularly susceptible 
 to plague. 
 
 In the Philippine Islands no specimens of 
 Gunomys have been observed, but 31, rattus and 
 31. decumanus are both present and numerous and 
 both are subject to plague, as shown by the presence 
 of the disease in specimens examined. 
 
ITS CONTROL AND SUPPRESSION 101 
 
 In view of the unreliability of the points of dif- 
 ference in rats usually given as identifying data, 
 such as the number and location of the mamm£e, the 
 variations in color and the peculiarities of the foot- 
 pads, the Javan observers depend upon the Con- 
 formation of the skulls for the determination of 
 genera, the skull of M, rattus being oval and arched, 
 that of M. decumanus more closely approaching the 
 square and rectangular conformation, and that of 
 Gunomys being broader, higher and longer than 
 either. 
 
 In M. 7'attus the prominent borders which sep- 
 arate the parietal from the frontal surfaces of the 
 skull are oval; in M. decumanus they are parallel 
 or slightly divergent; in Gunomys they are lyre- 
 shaped. 
 
 M. rattus M. decumanus Gunomys 
 
 I 
 
 To determine these differences the heads of the 
 rats are cut off, the tissues desiccated by antif ormin, 
 or by boiling and stripping. 
 
 From experiences in Porto Rico, Creel, of the 
 U. S. PubHc Health Service, concludes that M. 
 
102 PLAGUE 
 
 norvegicus {decumanus), while essentially a bur- 
 rowing animal and not addicted to climbing or 
 swimming, is nevertheless quite capable of doing 
 either. He was found to burrow in the hardest 
 earth to a depth of two and one-half feet and to 
 pass tlu'ough all kinds of wood, soft brick and lime 
 mortar, probably by gnawing. 
 
 The black rat and Alexandrine rat (M. rattus) 
 in Porto Rico, according to the same observer, do 
 not burrow at all, but can climb and jump in ex- 
 pert manner, and are the species found in the rural 
 districts, remote from houses. He found that all 
 varieties of rats may swim, from ships to the shore, 
 distances of from one-fourth to one-half mile, but 
 that they lack the sense of direction and probably 
 do not land from ships naturally in this manner 
 {Public Health Reports, No. 9, February 28, 1913) . 
 
 The female decumanus is a prolific breeder and 
 brings forth larger litters than the WIus rattus 
 female. 
 
 Mus decumanus is generally conceded to be 
 larger and more ferocious than 3Ius rattus. For 
 this reason he drives the smaller rats to the upper 
 floors, the decumanus species generally living near 
 the ground. He is a burrower and is rarely found 
 
ITS CONTROL AND SUPPRESSION 103 
 
 in the upper stories of buildings. Decumamis is 
 known as a wharf rat, but is rarely trapped on ships 
 on the Pacific Coast, according to the observations 
 of Surgeon Simpson of the U. S. Public Health 
 Service {Public Health Reports, April 11, 1913). 
 According to the same observer, Mus rattus is the 
 commonest ship -borne rat. He also states that the 
 black rat and the roof rat (Aleocandrinus) , both 
 varieties of 31. rattus, differ chiefly in color. They 
 live in upper floors, between ceilings, in walls and 
 roofs and are remarkable climbers as well as being 
 expert rope-walkers and wire-walkers. On account 
 of their natural wariness and caution it is not always 
 easy to induce them to enter or approach traps. 
 
 The photographs introduced were taken under 
 my direction in Manila in 1912, 1913 and 1914. 
 Some of them show the character of the house con- 
 struction in Tondo District, Manila, where plague 
 flourished in 1913. Others illustrate methods of 
 rat-proofing bamboo timbers in houses of light ma- 
 terial. These end openings were either closed by 
 introducing cement or by placing tight-fitting tin 
 cans over the ends of the bamboo rafters. 
 
 There are many interesting memoranda, gath- 
 
104 PLAGUE 
 
 ered and made in connection with our antiplague 
 work in Manila, especially concerning the location 
 and construction of rat nests found by our laborers ; 
 the materials used and the fabrication of the nests. 
 Memoranda giving details of rat catching and rat- 
 proofing are also presented and notes showing the 
 location of dead rats found in relation to dead hu- 
 man bodies of plague victims. 
 
 Notes concerning cases of multiple house in- 
 fection are also presented as being of possible in- 
 terest. 
 
 The Javan studies in 1911 and 1912 establish 
 the fact that it is possible to form a fair judgment 
 as to the length of time a rat has been dead, up to 
 ten or twelve days, from the condition and appear- 
 ance of the rat cadaver, both as to decomposition and 
 drying. A series of 50 rats was studied. It is to 
 be understood that the conditions under which these 
 observations were made were tropical conditions. 
 They would be fairly comparable with summer con- 
 ditions in America, but should not be followed too 
 closely at other seasons of the year. In my own 
 experience I have observed that ants are hkely to 
 attack the cadaver early and to obscure the deduc- 
 tions by their destruction of the body. 
 
PROGRESSIVE POST-MORTEM CIIAxVGES IN RAT CADAVERS. THE XUMBERS 
 INDICATE THE NUMBER OF DAYS AFTER DEATH 
 
ITS CONTROL AND SUPPRESSION 105 
 
 Dayi after deatb Appearance 
 
 First to third day. . . .Distention of the abdomen, in- 
 creasing. 
 
 Second to third day. .Loosening of hair by gentle pull- 
 ing. 
 
 Third to fourth day. Loosening of the epidermis by 
 
 gentle pulling. 
 
 Third to fifth day . . . Perforation of abdominal wall with 
 
 collapse and disappearance of 
 distention. This perforation 
 may result from bursting of ab- 
 dominal wall, or through anus, 
 vulva or thorax. 
 
 Fourth to sixth day. .Moist shrinking of the body. 
 
 Swarming of maggots. Spon- 
 taneous shedding of tufts of 
 hair. 
 
 Fifth to eighth day. .Drying of body. 
 
 Eighth to twelfth day. Complete dryness and rigidity. 
 
 Photograph (after Publications of the Civil 
 Medical Service in Netherlands ^ India) shows the 
 progressive postmortem changes in rat cadavers, the 
 numbers indicating the number of days after death. 
 
 A Collection of Notes Concerning Rat 
 Runs, Rat Nests, Their Location and Other 
 Data. — Attention is invited to the following collec- 
 tion of notes concerning rat runs, rat nests and their 
 locations and other data collected by the various 
 working parties under the direction of Sanitary 
 
106 PLAGUE 
 
 Inspectors Brantigan, Rentier and Kennard, of 
 Manila. 
 
 Special attention has been given to the finding 
 and destro}*ing of rat nests, and in tliis connection 
 please note that during the month of ^lay, 1913, 
 one party of workmen (20 men) mider Inspector 
 Brantigan, killed by hand 511 rats out of a total of 
 1319. This means that many nests were broken 
 up and that much breeding was interfered with. 
 In June, 1918, two parties (40 men) killed 772 
 rats by hand out of a total of 3019. 
 
 Tliis work occmTed in Tondo District in con- 
 nection with extensive cleaning and moving oper- 
 ations. 
 
 At 1279 C. Sandejas - 7 rats were found in 
 a nest at the foot of a cluster of bamboo trees, be- 
 tween the tiTinks. Xest was made of leaves. 
 
 At 728 C. Velasquez, Tondo, 12 rats were driven 
 from a burrow miderneath a thick cement floor by 
 formaldehyde gas delivered in the burrow tlu'ough 
 a rubber hose. This burrow was in sand and the 
 rats came out about ten minutes after the flow of 
 gas began. All were killed or captured and two 
 or three died from the effects of the gas. 
 
 - C. is abbreviation for Calle. the Spanish term for street. 
 
ITS CONTROL AND SUPPRESSION 107 
 
 On October 27, 1912, two of the rat terriers 
 belonging to the Bureau of Health caught 192 rats 
 in one storeroom at the ^lanila Railway Station, in 
 38 minutes. At various times they have killed from 
 10 to 25 rats at a single location, in connection with 
 the cleaning and moving work done by the laborers. 
 The dogs caught about 600 rats in all. 
 
 On March 11, 1913, 27 rats were caught by 
 laborers at 202 Calle Concha. They were nesting in 
 straw covers which had been removed from bottles. 
 
 On March 11, 1913, 13 rats were found be- 
 neath a pile of loose tiles at 203 C. Sardinas. The 
 nest was made of fibres from coconut shells and 
 straw. 
 
 On March 13, 1913, 12 rats were found among 
 stones scattered in a shallow pile on the ground at 
 C. Conservador (interior). Nest was made of rice 
 chaff and small pieces of cloth. 
 
 On March 15, 1913, 9 rats were caught at 1353 
 C. Anloague on the gromid floor beneath a pile 
 of boards. Nest was made of coconut fibre and 
 shavings. 
 
 On :March 16, 1913, 24 rats were caught at 934 
 (interior) Velasquez beneath a wood pile. Nest 
 was made of coconut- shell fibre and pieces of cloth. 
 
108 PLAGUE 
 
 On March 17, 1913, 14 rats were caught under 
 a pile of hay and straw at 173 Velasquez. Nest was 
 made from straw, chaff and hay. 
 
 The following articles of food were found in 
 the above-mentioned nests: chicken bones, rice, 
 coconut, fish and bread. 
 
 MEISIC DISTRICT 
 
 At 822 Sacristia 6 dead rats found in holes. 
 
 At 540 T. Alonso a family of 8 rats was smoked 
 out and all were killed. 
 
 At 514 same street 6 rats were smoked out and 
 killed. 
 
 At 538, interior, same street, 4 rats were smoked 
 out and killed. 
 
 At 546 same street 4 rats were smoked out and 
 .killed. 
 
 At 715 San Bernardo dead rat found in a hole. 
 Nest made of banana leaves and rags. 
 
 At 627, interior, Zacateros, 9 rats were smoked 
 out and killed. 
 
 At 669 Benavides 6 rats were smoked out of 
 four nms and were caught. 
 
 At 631 Zacateros 2 rats were smoked out and 
 killed. 
 
ITS CONTROL AND SUPPRESSION 109 
 
 At 417, interior, Misericordia, 4 rats were se- 
 cured in two holes under a tile floor. Many rats 
 were caught at this number (interior) in traps. 
 
 At 221 Espelita 7 rats were found in a nest 
 made of palm leaves and excelsior; location of run 
 way and nest beneath tile floor. 
 
 At 124 Tetuan, in a nest of straw and lint, 5 rats 
 were caught by hand, alive. 
 
 At 415 T. Alonso one live rat and 3 dead ones 
 were dug out from beneath a tile floor. 
 
 SAMPOLOC DISTRICT 
 
 At 1001 Bilibid Viejo there were 5 rat runs, 
 in a Chinese store. Eight rats were secured in a 
 nest under the cement floor. Nest made of straw 
 and paper. 
 
 At 928 San Sebastian there were 8 rat runs. In 
 one of them there were caught 8 rats. The nest 
 was made of straw. 
 
 At the same address, later, 3 rats were caught 
 in another run and 8 young rats, with eyes still un- 
 opened, were found in a nest of straw. A supply 
 of bread was on hand in this nest. 
 
 At 629 Tanduay 20 rats and nests of straw and 
 paper were found. 
 
110 PLAGUE 
 
 At the same address upon another day another 
 rat run was found and one large rat and 16 small 
 ones were taken from a nest made of rags, straw, 
 and fibres. 
 
 PACO DISTRICT 
 
 At 1115 San Andres in a Chinese tienda (food 
 store) , a long rat run and a nest of rags, straw, and 
 paper, and 30 small rats were found. 
 
 One nest in a bamboo tree 30 feet above ground 
 was found. Rats had been observed going up the 
 tree and one was caught at the foot of the tree in a 
 trap. 
 
 SAMPOLOC DISTRICT 
 
 At 629 Tanduay 14 young rats and a nest of 
 straw, paper and rags were found in a stable. 
 
 Same address, later, one rat run and nest of 
 straw and rags with one large rat and 16 small ones 
 were found. 
 
 TONDO DISTRICT 
 
 March 27, 1913, one rat was caught alive inside 
 of a bamboo timber in house at 51, interior, Pes- 
 queria. 
 
 At 631 Azcarraga 4 young rats were found in 
 a nest of paper, leaves, and hay. Chicken bones, 
 crab shells, and rice were present in the nest. 
 
ITS CONTROL AND SUPPRESSION 111 
 
 A young python was caught in a lumber yard in 
 the Santa Cruz District in June, 1913. In his 
 stomach was found a half-grown rat. Another 
 snake was caught in a rat trap at the same addi'ess 
 about the same time. 
 
 Plan for Household Rat Destruction. — 
 The following plan for household rat destruction 
 was proposed by me to the Director of Health. It 
 is considered worthy of trial if rat plague appears 
 in new districts. 
 
 Proposal for periodic household rat poisoning in 
 Manila. 
 
 Proposed that, upon a certain day of each week, rat 
 poison be issued free to all applicants (householders) in 
 Manila who agree to place same about their premises, 
 permitting the poison to remain in place for 48 hours. 
 
 Instructions and poison placards to be issued with the 
 poison. Issues to be made from Station Health Offices and 
 records of issue to be kept. 
 
 Collections of dead rats to be made at the end of 24i 
 hours and 48 hours by Bureau of Health employees. 
 Poison portions to be collected and turned in at the 
 Station Health Offices at the end of 48 hours, that is, at 
 the time of the last rat collection. Rats to be tagged 
 and examined for plague in the usual manner. 
 
 Due newspaper notice of the plan and of the gratuitous 
 issue of poison to be given to the people and their coopera- 
 tion requested. 
 
 Plan to be tested for at least two months. 
 
112 PLAGUE 
 
 MULTIPLE HOUSE INFECTION 
 Memorandum concerning 1364 Calle Sande: 
 Within 72 hours (April 25-27) five fatal cases 
 of plague, all in Filipinos, occm'red in Manila. The 
 five deceased persons lived at 334 C. P. Rada 
 (Meisic), 1419, interior, C. Dagupan, 1364 C. 
 Sande (Tondo), 642 C. Ylala (Meisic), and 1492, 
 interior, C. Dagupan (Tondo). 
 
 The following relationships were established by- 
 inquiry and investigation and the circumstances 
 point strongly to a common source of infection and 
 to a single geographic focus of plague infection in 
 connection with all of the cases, viz.: at 1364 C. 
 Sande (Tondo). 
 
 Jose Raymundo, boy, aged fifteen, lived at 334 C. P. 
 Rada and worked daily until taken sick on Tuesday, 
 April 22, at 1364 Sande, in the shop of Simplicio Enriques, 
 a silversmith, who lived part of the time at the same 
 address. 
 
 Jose Raymundo died of bubonic plague at San Lazaro 
 Hospital on Friday, April 25, 1913. 
 
 Norberta Mendoza, woman, aged fifty-six, lived at 
 1418, interior, C. Dagupan. She was the mother-in-law 
 of Simplicio Enriques, the silversmith at 1364 Sande, and 
 visited her son-in-law there frequently and within a few 
 days of her last illness. She was taken sick April 22 and 
 died at 1419, interior, C. Dagupan, on the morning of 
 
ITS CONTROL AND SUPPRESSION 113 
 
 April 26. At autopsy at San Lazaro morgue, the same 
 day, bubonic plague was found to be present and the 
 cause of her death. 
 
 Trinidad Galves, a young woman, aged sixteen, lived 
 at 1364 Sande and was taken sick there on April 25. She 
 was removed to San Lazaro Hospital and died there 
 April 26, extensive plague lesions being found at autopsy. 
 
 Pablo Banzon, man, aged twenty-six, living at 646 
 C. Ylaya, was taken sick on Friday, April 25. He was 
 removed to San Lazaro Hospital Saturday afternoon 
 and died there Sunday evening, April 27. He was shown 
 to have plague by bacteriologic examination made at the 
 Bureau of Science. He worked at 1364 Sande as a silver- 
 smith, with Jose Raymundo and was employed by 
 Simplicio Enriques. 
 
 Simplicio Enriques, aged twenty-seven, a silversmith, 
 conducting his business at 1364 C. Sande and employing 
 Jose Raymundo and Pablo Banzon, was taken sick about 
 April 23. He moved to two different houses in the in- 
 terval between the onset of his sickness and his transfer 
 to San Lazaro Hospital on April 27, first to 1419 C. 
 Dagupan, interior, where he remained until the death of 
 his mother at this house ; then to 1492 Dagupan, interior, 
 from which place he was transferred to San Lazaro Hos- 
 pital, where he died with bubonic plague a few days later. 
 Diagnosis was confirmed at autopsy. 
 
 The two women were patients of Dr, Hernando 
 of Calle Ylaya. He recognized the case of the elder 
 woman as a probable case of plague, after death, 
 and reported the matter to the Bureau of Health. 
 
 The house at 1364 C. Sande is of the type in 
 
114 PLAGUE 
 
 which cases of rat plague and hmnan plague have 
 recently been found. In our operations to put the 
 house in a safe condition we found one dead rat, 
 munimified, in the basement. Unfortunately, the 
 workmen who swept it out did not note the exact 
 location at which it was found. The house is in the 
 midst of the district where rat plague has raged 
 since early in March, 1913. The basement con- 
 tained unauthorized and illegal sleeping rooms until 
 a few days before this outbreak when they were 
 removed in the course of our antiplague operations. 
 The building is constructed of bamboo with a nipa 
 thatch roof. 
 
 The front part of the basement was paved, but 
 the pavement was undermined and broken. Being 
 convinced that dead plague rats were present in 
 the vicinity of this house and probably within it, I 
 directed that the cement floor under the silversmith 
 shop and the barber shop, located upon the grotmd 
 floor at this address, be torn up. Accordingly, this 
 was done (April 28) and three dead rats and one 
 live one were found beneath the cement. As the 
 bodies were mmiimified and unfit for bacteriologic 
 examination they were burned. The living rat was 
 examined at the Bureau of Science but was found 
 
ITS CONTROL AND SUPPRESSION 115 
 
 to be healthy. The cement floor was broken and 
 permitted fleas from the dead rats to enter the base- 
 ment room of the house which was occupied by the 
 silversmith shop. The rats doubtless died from 
 plague and the hungry fleas in due time attacked 
 the nearest persons at hand, the unfortunate occu- 
 pants of the silversmith shop and the two women 
 who frequented the room also. 
 
 These facts account for the epidemic at 1364 
 Sande very completely. 
 
 The premises at 1364 Calle Sande were quaran- 
 tined by the following order : 
 
 Manila, April 27, 1913. 
 
 The premises 1364 Sande are hereby declared in 
 Quarantine for Bubonic Plague by order of the Director 
 of Health. 
 
 The inmates will be permitted to leave the building 
 and find quarters elsewhere, provided they leave their ad- 
 dresses with the policeman in charge, so that they may be 
 readily found. They must remain in the District of Tondo. 
 If they remain in the house they will be obliged to stay 
 in the upper story of the house and will have to arrange 
 for meals to be sent in. 
 
 The barber shop and " platero " shop are hereby 
 ordered closed until further orders. 
 
 By order of the Director of Health. 
 
 [Signed] T. W. Jackson, 
 
 Medical Inspector, in Charge of Plague Suppression. 
 
116 PLAGUE 
 
 Memorandum reporting circumstance surround- 
 ing 2 cases of plague at 1226 C. Juan Luna (May 
 17, 1913) : 
 
 Valeriano Lausin,. aged fourteen, Filipino male, 
 Carmelo maker by trade but out of work at time he was 
 taken sick, recently removed to this house from 917 C. 
 Jaboneros where he had been employed. The patient 
 fixes the date at about a week previous to his sickness, but 
 the proprietors of 917 Jaboneros are positive in their 
 statement that he left the place where he lived and worked, 
 at least two weeks before. This boy recovered. 
 
 The circumstances and especially the occuiTcnce 
 of a second case at 1226 C. Juan Luna, indicate 
 that infection was incurred here. 
 
 Moreover, this house is in the midst of a rat- 
 plague infected district. 
 
 The house is of bamboo and nip a construction 
 and contained illegal basement rooms until a week 
 ago. About 60 persons lived in this house which 
 was once licensed as a tenement but which is un- 
 sanitary in a multitude of ways. Bamboo construc- 
 tion, overcrowding, dirty condition and absence of 
 proper drainage, water-closet, proper kitchens and 
 paved ground floors, together with bad ventilation, 
 made it a dangerous habitation and the added con- 
 
ITS CONTROL AND SUPPRESSION 117 
 
 dition of plague infection made it necessary to 
 vacate and quarantine the building. 
 
 On May 15, at the daily inspection of contacts 
 in the house 1226 C. Juan Luna, Filomena Sunga, 
 aged nineteen, and a relative of the owner of the 
 building, was found to be sick. Her only symptom 
 was fever, but she was transferred to San Lazaro 
 upon suspicion and promptly developed symptoms 
 of plague. She died in a few days and the diagnosis 
 of plague was verified at autopsy. The following 
 order was issued: 
 
 Station " C," Tondo, Bureau of Health, 
 
 Manila, P. I., May 15, 1913. 
 By order of the Director of Health, the house No. 1226 
 C. Juan Luna is declared infected and is quarantined this 
 date, for Bubonic Plague. The house will be vacated and 
 a policeman will register the names of all residents and 
 the addresses to which they remove. 
 
 The residents may remove their personal effects but 
 will not be permitted to return while the quarantine is in 
 
 ^^^^*- [Signed] T. W. Jackson, 
 
 Medical Inspector, Station "C," Tondo. 
 
 Memorandum: Human body (dead from 
 plague) and dead rats found in the same basement 
 room. Upon March 21, 1913, a Filipino laborer 
 living at 140 Calle Perla, Tondo, was found dead 
 from bubonic plague. 
 
118 PLAGUE 
 
 Upon careful investigation and search of the 
 premises the following findings were disclosed: 
 
 One rat, large, mummified and dry and there- 
 fore dead for at least one week, was found clinging 
 to a bamboo wall just back of the cot upon which the 
 dead human body was found. 
 
 In a section of bamboo, in a timber constituting 
 the ceiling of the basement and also the upper part 
 of the door frame, a rat, dead and dried up, was 
 found. This section was the end section of the 
 timber which was partly covered with nipa thatch, 
 with which the sides of the house were covered. The 
 ends of a number of the outside rafters (bamboo) 
 were found to be gnawed through. 
 
 Similar conditions were found in adjoining 
 houses and in one case a live rat was driven out of 
 a nest in the bamboo. 
 
 Sample of Detailed Orders Issued. — Sample 
 of detailed orders issued by Medical Inspector in 
 Charge of Plague Suppression. Similar orders 
 were issued whenever new districts were entered or 
 new work undertaken. 
 
 Memorandum Order. Effective March 25, 1913: 
 Beginning to-day, 13 men under Assistant Inspector 
 Pards, will commence cleaning operations at C. Ostra, 
 
BAMBOO HOCSE SUPPORTS SEALED WITH CEMENT TO PREVENT ENTRANCE OF RATS 
 (MANILA PLAGUE CAMPAIGN) 
 
ITS CONTROL AND SUPPRESSION 119 
 
 extending from the Bay to C. Sande and will clean towards 
 C. Moriones. They will be provided with a disinfecting 
 pump and will disinfect the ground surfaces wherever 
 disturbed, outdoors and indoors. Cleaning is to be done 
 in the most thorough manner possible, searching mean- 
 while for rat nests and rat harbors ; re-piling wood, tiles, 
 stones and merchandise; moving all movable goods out of 
 doors in their search for rats and rat-holes or nests. All 
 goods are to be piled above ground at an elevation of at 
 least one foot. All bamboo beds and bamboo rafters and 
 parts of the house (in the basements) made of bamboo or 
 of double walls are to be thoroughly investigated for rats. 
 All foodstuff attractive for rats is to be placed in covered 
 boxes or galvanized iron cans, tin cans or barrels, with 
 tight-fitting covers. Special attention is to be paid to 
 straw, hay, shavings, grain, rat-holes, and food. 
 
 Two men will be detailed to cement up ends of bamboo 
 and rat-holes, but will not do general repairing. They 
 will carry materials for mixing cement as needed and will 
 not be wasteful of materials. 
 
 If this force proves to be insufficient in numbers, addi- 
 tional men may be detailed from the other working parties. 
 
 [Signed] T. W. Jackson, 
 
 Medical Inspector in Charge of Plague Suppression. 
 
 Specimen order issued to Sanitary Inspector 
 assisting in Plague Suppression by Medical In- 
 spector in charge. 
 
 Sanitary Inspector, Bureau of Health: 
 Please place the gang of workmen under your charge 
 in the square bounded by Calles Velasquez, Moriones, 
 
120 PLAGUE 
 
 Concha and Manila Bay which is infected with rat plague. 
 Treat the houses and properties there in the same manner 
 in which other plague-infected districts have been treated, 
 viz. : by policing the houses and yards, vacating all base- 
 ments of light-material houses in which human habitations 
 are illegally present; removing (with the consent of the 
 occupants) all unauthorized basement sleeping places, 
 beds, platforms, etc., and other illegal structures, closing 
 up the open ends of bamboo rafters or timbers of the house 
 with tin or cement. 
 
 Where the occupants resist this action sanitary orders 
 should be issued in the usual manner and interference 
 should be stopped until the order is served and complied 
 with. There are a number of most insanitary and unsuit- 
 able shelters of bamboo, tin, etc., used for houses by a 
 number of families in this square and it is desirable to 
 tear down these huts if permission can be secured. If 
 permission is refused orders should be issued on the usual 
 form. 
 
 [Signed] T. W. Jackson, 
 In Charge of Plague Suppression. 
 
 Specimen order issued by the Medical Inspector 
 in charge of Plague Suppression. 
 
 Station " C," Tondo, May 21, 1913. 
 
 Redistribution of rat catchers and laborers engaged in 
 antiplague work. Effective May 2, 1913. 
 
 Sanitary Inspector Kennard and 20 rat catchers will 
 move into Tondo District and trap and poison rats in the 
 district bounded on the west by Manila Bay and on the 
 east by Estero Reina. The work will be begun at the 
 extreme north water boundary of this district and will 
 proceed toward the south. 
 
ITS CONTROL AND SUPPRESSION 121 
 
 Sanitary Inspector Brantigan with a similar number 
 of rat catchers (20) will work within the same east and 
 west boundaries and will begin trapping and poisoning at 
 Calle Moriones, proceeding north. The poisoning and 
 trapping is to be done in the most thorough manner pos- 
 sible, as this is a dangerously infected district and rat- 
 plague must be controlled and terminated here. 
 
 The laborers, 60 men, divided into 4 parties of 15 men 
 each under Assistant Sanitary Inspectors Jesus, De la 
 Rosa, Laxamana and Paras, will continue the cleaning 
 operations now under way on both sides of C. Juan Luna 
 south of C. Moriones (plague localities in the same neigh- 
 borhood), and thoroughly disinfect. 
 
 One party of 15 men will work in the vicinity of C. 
 Perla, vacate basements as habitations, search for dead 
 rats in yards, houses, bamboos, under broken concrete, 
 etc., and will close up openings in structural bamboo by 
 means of tin and cement. Emphasis is placed upon the 
 necessity for permanently vacating basements and men 
 will be sent back over the ground daily to see that the 
 persons moved out do not return. Reports are desired so 
 that prosecutions for violations of the law may be insti- 
 tuted if necessary. 
 
 [Signed] T. W. Jackson, 
 
 Medical Inspector in Charge of Plague ^Suppression. 
 
 Specimen order issued to Assistants. 
 
 May 4, 1913. Station "C," Bureau of Health: 
 Please place work parties in (interior) 1627—1629 
 Sande and 525 C. Azcarraga, to clean, disinfect and thor- 
 oughly investigate these premises and the houses, stables 
 and other buildings in the vicinity. Search for rats, liv- 
 
122 PLAGUE 
 
 ing and dead, rat nests and rats in bamboos and wood 
 piles, stone piles, stables, under planks and elsewhere. 
 Cement the openings in bamboos in houses or close with 
 tin. Make notes on needed structural work. Do the work 
 as thoroughly as possible. 
 
 [Signed] T. W. Jackson, 
 Medical Inspector in Charge of Plague ^Suppression. 
 
 Method of Procedure in Collecting and 
 Forwarding Rats Suspected or Plague Infec- 
 tion TO THE Laboratory in Manila, P. I. — Rat 
 catching, — trapping and poisoning, — is conducted 
 in accordance with instructions contained in the 
 Sanitary Inspector's Handbook (pp. 36, 37, 38) 
 issued by the Bureau of Health. 
 
 Rats are collected in Manila and forwarded to 
 the Bureau of Science for autopsy and for biologic 
 examination for the presence of plague bacilli in 
 the following manner: 
 
 The various groups of rat catchers are provided 
 with receptacles (iron pails) and a supply of a 
 mixture of kerosene, cresol and water (kerosene 
 10 parts, cresol 2 parts; water 88 parts). 
 
 In these vessels, filled with the pulicidal mixtm-e, 
 the rats are immersed, with a minimum amount of 
 handling, as soon as they are found (whether in 
 traps or dead from poison). 
 
ITS CONTROL AND SUPPRESSION 123 
 
 If captured alive they are killed and then 
 promptly immersed. The mixture must be well 
 shaken or stirred when used, as it separates upon 
 standing. The immersion is, of course, for the pur- 
 pose of destroying any fleas which may be present 
 upon the captured rat. 
 
 A paper tag showing the date and the exact 
 location of the place of capture, with the name or 
 group number of the rat catcher, is next affixed to a 
 foot or to the tail of the rat and firmly tied upon 
 the same, where it remains until the rat cadaver is 
 finally disposed of. This tag is a card of strong 
 Manila paper and the record upon it is made with 
 an ordinary lead-pencil, as both ink and indelible 
 pencil marks are apt to become illegible from wet- 
 ting, whereas lead-pencil marks are little affected 
 thereby. 
 
 If desired, the disinfected tag in any given case 
 of rat plague may be returned to the Bureau of 
 Health, for identification, where an accurate record 
 of every rat captured is kept. 
 
 After dipping and tagging, the rats are taken 
 to a central point, again dipped, and placed in large, 
 tightly-covered, galvanized iron cans, in which con- 
 tainers they are delivered to the laboratory by cart, 
 once or twice daily. 
 
124 PLAGUE 
 
 The Case of Mr. C. — The following are the 
 facts concerning the case of Mr. W. C, a prominent 
 American resident of INIanila who suffered and died 
 from plague in 1914. 
 
 Mr. C, an editor, was taken ill with plague 
 on the night of September 18, sought medical ad- 
 vice and entered St. Paul's Hospital September 19, 
 and was transfen^ed to San Lazaro Hospital, Sep- 
 tember 20, with an established chnical and bac- 
 teriologic diagnosis of bubonic plague. He sur- 
 vived till September 22. 
 
 Upon September 21, in the course of disinfect- 
 ing the business office of Mr. C, located in a district 
 which had furnished a number of cases of both rat 
 and human plague, a dead rat, mummified, was 
 found in the right hand drawer of his desk and 
 fleas were seen to hop from the drawer upon open- 
 ing it. 
 
 A flea killed by the disinfecting mixture at this 
 desk was identified at the Bureau of Science as a 
 rat flea (Xenopsylla cheopis). 
 
 The rat cadaver was sent to the Bureau of 
 Science and the following facts were reported from 
 there some days later: 
 
 The mummified rat and skeleton were pulver- 
 
ITS CONTROL AND SUPPRESSION 125 
 
 ized in a sterile mortar and an emulsion was made 
 and injected into guinea-pigs. The animals died 
 from plague in a few days and plague bacilli were 
 recovered from the tissues, as well as from the rat 
 cadaver, by culture. 
 
 A second rat cadaver, found at the same time 
 in the same building, dm-ing cleaning operations, 
 was similarly treated with identical results. 
 
 There could scarcely be a stronger chain of con- 
 dancing evidence against the rat and the flea, nor a 
 more complete and convincing explanation of 
 Mr. C.'s death than that afforded by these estab- 
 lished facts and official documents. So far as I 
 know there is no more striking case on record in 
 the modern history of plague. 
 
 Lettee of Warning and Appeal. — The fol- 
 lowing letter of warning and appeal for coopera- 
 tion was suggested and framed by me February 10, 
 1914, at the time that extensive rat plague was 
 discovered in the heart of the business district of 
 Manila. I presented it to the Director of Health 
 with a strong recommendation for approval and 
 publication and after consideration he approved 
 and authorized publication upon February 10. No 
 change was made in the wording of the proclama- 
 
126 PLAGUE 
 
 tion, but it was issued over the signature of the 
 Director of Health to give added force and au- 
 thority to the appeal. The results were, as I had 
 hoped they might be, highly beneficial. The tak- 
 ing of the public into the confidence of the health 
 authorities brought about a cooperation, without 
 which our efforts in this difficult situation would 
 have been sadly handicapped. It is my belief that 
 this method should often be used by health author- 
 ities, particularly where an intelligent community 
 is threatened. 
 
 To Whom It May Concern : 
 
 You are hereby informed that the district bounded by 
 Calles Rosario, Juan Luna, Dasmarinas and Plaza Cal- 
 4eron (and possibly the neighborhood bordering upon this 
 congested district) is a dangerous one for all persons liv- 
 ing or conducting business therein, on account of the 
 presence there of extensive rat plague. Six human cases 
 (with five deaths) have recently developed there and many 
 dead rats have been found. All human cases have been 
 directly traced to rats dead from plague. 
 
 The Bureau of Health is now doing everything within 
 its power to make this district safe, but the attention of 
 all citizens, property owners and tenants is called to the 
 fact that they are required by law to keep their premises 
 free from rats and to abolish all structural conditions of 
 the buildings which favor the harboring of rats. Tliis 
 means rat-proofing, and owners arc earnestly urged to 
 
ITS CONTROL AND SUPPRESSION 127 
 
 perform this necessary work now, under the direction of 
 the Bureau of Health. 
 
 As a temporary expedient and safeguard all interiors, 
 walls, floors and ceilings should be sprayed with kerosene 
 daily, or at intervals of two days, to kill the fleas which 
 carry plague from rats to human beings. All dark in- 
 sanitary places used for living rooms should be vacated 
 at once; all merchandise should be piled upon trusses at 
 least a foot above the floor ; all straw, shavings and other 
 material attractive to rats for nesting, should be removed 
 and burned and all food materials upon which rats may 
 feed and live should be placed in covered boxes, bins or cans. 
 
 All rat-holes should be permanently closed and all 
 broken cement or masonry should be repaired. 
 
 Observance of these instructions may save the lives 
 of yourselves, your families and your tenants. It is your 
 duty to do your part in this matter, a part which neither 
 the Bureau of Health nor the Government can do for you. 
 
 Through very great effort the Bureau of Health has 
 controlled plague in Manila and the Philippine Islands 
 during the last two years. 
 
 Residents must now do their part, and owners of 
 property must permanently make their buildings safe for 
 tenants, both for business and residential purposes. 
 
 Bacteriologic Observations Made by Dr. 
 Otto Schobl. — The following observations upon 
 the bacteriologic aspect of the Manila epidemic 
 which we are considering were made by Dr. Otto 
 Schobl of the Biological Laboratory of the Bureau 
 of Science, Manila, and pertain to the cases of the 
 
128 PLAGUE 
 
 first year of the epidemic. They were printed in 
 the December number of the Philippine Journal of 
 Science in 1913, but as they belong so definitely to 
 the epidemic I am describing and as Dr. Schobl has 
 expressed his willingness for me to quote them in 
 full, I gladly accept his permission. Dr. Schobl 
 advanced the possibilities of blood-culture diagno- 
 sis to such a point of rehabihty that it became prac- 
 tically possible for us to expect positive culture in 
 nearly every case of true plague and the whole 
 matter of bacteriologic diagnosis was perfected to 
 a high degree of efiSciency under his administra- 
 tion of the laboratory work. 
 
 He relates his observations as follows: 
 
 During the recent outbreak of plague in Manila, I had 
 the opportunity to make certain observations ■which are 
 of interest. These observations were made in the exam- 
 ination of: (1) Specimens taken from patients and from 
 dead bodies at autopsies, (2) samples of blood-sucking 
 insects collected in houses where plague patients had lived, 
 
 (3) rodents caught by trap or poisoned in the parts of the 
 city where plague cases occurred from time to time, and 
 
 (4) domestic animals suspected of plague infection. 
 
 I. Bacteeioix)gical Examination of Plague Patients 
 
 In order to secure as early diagnosis as possible, the 
 following procedure of investigation was adopted: 
 
 1. The bubo was aspirated by means of a sterile hypo- 
 
ITS CONTROL AND SUPPRESSION 129 
 
 dermic syringe. The material thus obtained was placed 
 in the water of condensation of an agar-slant culture tube. 
 
 2. At least 7 centimetres of blood were withdrawn 
 from the cubital vein by means of another sterile syringe, 
 and 5 centimetres of it were placed in an Erlenmeyer's 
 flask, containing 200 centimetres of neutral meat broth. 
 The rest of the blood was emptied into a sterile tube, and 
 used for agglutination tests. 
 
 Cultures obtained by this method were examined micro- 
 scopically, and the growths on various culture media were 
 studied. Gram stain, Loffler's methylene blue, and hang- 
 ing-drop method were used. Polar-staining and chain 
 formation in liquid media and the characteristic type of 
 colony on the surface of agar were looked for. Animal 
 inoculation was performed in every case, and the culture 
 isolated from each case was identified by agglutination 
 test, rabbit's immune serum being used. 
 
 The results of the bacteriological examination of a 
 series of 24 patients are tabulated in the two following 
 tables. Table I includes the fatal cases and Table II 
 those cases which recovered. 
 
 The diagnosis of plague could be safely made from the 
 microscopical examination of the liquid aspirated from the 
 bubo in the majority of the cases. However, in certain 
 instances the amount of the aspirated fluid being small 
 and the bacilli very few, it was impossible to diagnose the 
 case, especially when the cultures from the bubo were 
 negative. Repeated examination of the patient was neces- 
 sary under those conditions, but it happened in cases 22 
 and 23 that the patients died of plague before a second 
 examination could be made. The smears and cultures 
 from case 22 remained sterile, while the smears and cul- 
 9 
 
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132 PLAGUE 
 
 tures made from the swelling on the neck of patient 23 
 revealed the presence of pneumococci. Both patients died 
 of plague, as was ascertained by examination of the organs 
 after death. 
 
 Two of the patients, cases 8 and 12, had numerous 
 plague bacilli in the sputum at the time when the expec- 
 toration showed the presence of blood (twenty- three and 
 one-half and eighty- two hours, respectively, before death). 
 In 3 cases I was able to prove the presence of Bacillus 
 pestis in the skin lesions, intra vitam, fifteen, twenty-two, 
 and forty-eight hours, respectively, before death. In case 
 18 there was no doubt that the skin lesions, which cov- 
 ered the whole body and the face, were of secondary 
 nature, as the patient died shortly afterward. It was 
 undoubtedly a case similar to those reported by Gotschlich 
 and Zabolotny.^ In the other two patients there was 
 only 1 maculopapulous efflorescence on the foot in case 1 
 (with a corresponding femoral bubo) and 2 lesions of the 
 same type on the arm and forearm in case 4 (with a cor- 
 responding axillary bubo). It is possible that these 
 lesions were the original port of entry of infection. Num- 
 erous plague bacilli were found in the skin lesions of these 
 cases, both microscopically and in culture. 
 
 The plague patients tabulated in Table II recovered. 
 They were all treated with antiplague serum'. While 
 cases 5, 2, 19, and 24* appeared cKnically to be rather 
 severe, cases 2 and 20 were mild. 
 
 It can be seen from the table that the plague bacilli 
 may not be detected in the enlarged gland at first ( case 2 ) 
 and that their presence may be revealed only after re- 
 
 ^ KoUe und Wassermann : Handbuch der pathogenen 
 Mikroorganismen. Gustav Fischer, Jena (1903) 2, 521. 
 
ITS CONTROL AND SUPPRESSION 133 
 
 peated examination of the bubo. It is also evident from 
 the results of repeated examinations that the pla,gue bacilli 
 disappear from the infected gland in a comparatively 
 short time, as a rule at the time when pus starts to form. 
 Contrary to the findings in patients who died, distinct 
 phagocytosis was noticed in the smears made from the 
 aspirated liquid in those patients who recovered and who 
 had been treated with serum soon after the onset of the 
 disease. It is undoubtedly tl^iis process that clears the 
 gland of the infectious agents. 
 
 The general opinion in regard to the presence of BacU- 
 lus pestis in the circulating blood seems to have been, as 
 Thompson remarks, that '" the bacillus is rarely to be 
 found in the peripheral blood stream before the agonal 
 stage." ^ 
 
 The Austrian Commission, using few drops of blood, 
 found positive blood culture in 40 per cent ; Calvert in 
 Manila in 100 per cent when examined twenty-four ?iour3 
 before death ; Choksy, Berestneff. and Mayr in 45 per 
 cent ; and Greig in 60 per cent. The Indian Commission 
 examined 28 patients, and obtained positive blood cul- 
 tures in 16 out of 23 fatal cases. Not a single positive 
 blood culture was obtained from the patients who sur- 
 vived. The time of blood examination in positive cases 
 was three and one-half to seventy-five and one-half hours 
 before death. The amount of blood used was 1 cubic 
 centimetre. Only 6 out of the SO samples, which gave 
 positive blood culture, were found positive by microscopical 
 examination of blood smears. The following conclusions 
 are based on these observations in regard to the septicEemic 
 stage of bubonic plague: (1) *'A severe septicaemia may 
 
 * Journ, Hyg.j Cambridge (1906)^ 6, 558. 
 
134 PLAGUE 
 
 be present at a comparatively early stage of the disease 
 and for a considerable number of hours before death, and 
 (2) the septicaemia may be of an irregular and fluctuating 
 type." 5 
 
 From the tables it will be seen that out of 15 patients 
 examined by me, 14; gave positive blood culture; and of 
 these 3 recovered. One blood culture revealed the pres- 
 ence of streptococcus in addition to Bacillus pestis. The 
 results of the examinations tabulated in Tables I and II 
 show, in agreement with the findings of the Indian Com- 
 mission, the occasional early occurrence of plague bacilli 
 in the blood stream, as the time of examination in the 
 positive cases varied from one hour to one hundred six 
 hours before death. In consideration of the ephemeral 
 character of the septicemic stage of plague, as evidenced 
 by repeated blood cultures in the three patients who re- 
 covered, one can hardly avoid the impression that there 
 is a certain degree of septicaemia in every case of plague. 
 The possibility of detecting the bacillus in the circulat- 
 ing blood increases in proportion with the quantity of 
 blood used for culture. The best chance to recover plague 
 bacilli from the circulating blood seems to be in the stage 
 of high fever and general prostration. 
 
 The phenomenon of agglutination of plague bacilli by 
 the serum of patients was first observed by Wissokowitsch 
 and Zabolotny in 1897 ^ and later confinned by the Ger- 
 man Plague Commission. Vagedes, Klein, and others ° 
 pointed out the defects of the reaction as a diagnostic 
 
 ^ Ibid. (1907), 7, 395. 
 
 " Referred to in Kolle und Wassermann : Handbuch der 
 pathogenen Mikroorganismen (1903), 2, 524. 
 
ITS CONTROL AND SUPPRESSION 135 
 
 means. Aside from the technical difficulties, the reaction 
 was found inconstant, and its occurrence was not noticed 
 until the second week of the disease and even then only 
 in low dilutions of the serum. 
 
 Although the recent work of Strong"^ and of Strong 
 and Teague * has reduced the technical difficulties, the 
 fact remains that positive agglutination of plague bacilli 
 by the patient's serum cannot be obtained in the first week 
 of the disease, and, therefore, the isolation of plague 
 bacilli from the body of the patient is still the only quick 
 and safe method of plague diagnosis. 
 
 Having utilized the technic devised by Teague, I have 
 had no difficulty in performing the agglutination test in 
 plague. The emulsion of plague bacilli, to be used for 
 the test, was prepared by suspending young cultures of 
 virulent plague bacilli, grown at 30° C, in salt solution 
 and filtering the suspension through filter paper. No 
 antiseptic was added nor heat applied. Serial dilutions 
 of unheated patient's serum were mixed with equal amounts 
 of bacterial suspension in small test tubes. Incubation 
 at 35° C. followed. Controls, consisting of serial dilutions 
 of normal human serum as well as bacterial suspensions 
 without serum, excluded any possible error which might 
 have been caused by spontaneous sedimentation of the 
 bacterial suspension ; while a parallel test with highly 
 agglutinant serum facilitated the reading of positive 
 results. 
 
 Altogether, 22 tests were performed on 15 patients, 
 11 of whom were fatal cases and 4 of whom recovered. 
 
 "^ The Philippine Journal of Science, Sec. B. (1907), 2, 
 155. 
 
 « Ibid. (1912), 7, 194-201. 
 
136 PLAGUE 
 
 In the negative reactions, the duration of the disease at 
 the time of examination ranges from two to six days. 
 The non-fatal cases showed slight agglutination from the 
 sixth day on. From that day, the agglutination titer of the 
 serum was found to rise, and the agglutinins persisted in 
 the blood of convalescents up to the seventh week of the 
 disease.^ 
 
 It must be borne in mind that the patients, who showed 
 positive agglutination, had been vigorously treated with 
 antiplague serum. Nevertheless, in consideration of the 
 low titer of the curative serum (dilution 1 : 32, agglutina- 
 tion positive; dilution 1: 64, agglutination negative), the 
 rise of the agglutinant power of the patient's serum in 
 dilutions higher than 1 : 16 cannot be explained as wholly 
 due to passive immunity, but rather to active immunity 
 arrived at on the principle of simultaneous immunization. 
 
 From the preceding observations the following con- 
 clusions are drawn: 
 
 1. The importance of blood cultures as a diagnostic 
 means is evident from the fact that positive blood culture 
 was obtained in practically every case that was examined 
 in the febrile stage of the disease, even when buboes or 
 signs of pulmonary involvement had not been detected 
 clinically. 
 
 2. It is also evident that Bacillus pestis may be found 
 in the circulating blood of the patients even in cases which 
 subsequently recover. 
 
 3. The period of time during which Bacillus pestis 
 circulates in the blood is evidently short and irregular. 
 
 " It is hoped that it will be possible to examine some of the 
 survivors for agglutination from time to time. 
 
ITS CONTROL AND SUPPRESSION 137 
 
 4. Mixed infection may be encountered in plague sep- 
 ticaemia {Streptococcus, Pneumococcus) . 
 
 5. The agglutination test is of no value for the diag- 
 nosis of plague, as it was found positive only in con- 
 valescents. 
 
 6. Phagocytosis of plague bacilli in the bubo was 
 noticed only in patients who recovered after being vigor- 
 ously treated with curative serum. 
 
 7. The presence of numerous plague bacilli in com- 
 paratively insignificant skin lesions during the life of the 
 patient points to the possibility of direct transmission, 
 while the fact that a patient without any apparent bubo, 
 who is not so sick as to be detained from his daily occupa- 
 tion, may expectorate large numbers of plague bacilli, are 
 facts of great importance with regard to the communica- 
 tion of the disease. It is obvious that the last-mentioned 
 condition might, and very likely does, give rise to an epi- 
 demic of pneumonic plague if the atmospheric and sanitary 
 conditions are favorable. 
 
 II. Observations on the Transmission of Plague by 
 Blood-sucking Insects 
 
 Judging from the data which have been collected from 
 the literature ^^ on the transmission of plague (Table III), 
 Simond seems to have been the first to call attention to 
 
 ^^ Centralbl. f. Backt., 1 Abt. (1897), 22, 87, 437. Re- 
 port of Indian Plague Commission (1898-99). Zeitschr. f. 
 Hyg. u. Infectionskrankh. (1901)^ 36, 89. KoUe imd Wasser- 
 mann: Handbuch der pathogenen Mikroorganismen (1903), 2, 
 538. Zeitschr. f. Hyg. u. Infectionskrankh. (1905), 51, 368. 
 Journ. Hyg., Cambridge (1907-10), plague numbers. Ibid. 
 (1908), 8, 162, 260. 
 
138 
 
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ITS CONTROL AND SUPPRESSION 139 
 
 the important part which blood-sucking insects, particu- 
 larly fleas, play in the transmission of plague. Although 
 many investigators have been successful in demonstrating 
 the presence of Bacillus pestis in the digestive system of 
 blood-sucking insects, it was not until the experiments of 
 Gauthier and Raybaud that the actual transmission of 
 plague infection by fleas was convincingly proved. Ever 
 since the exhaustive and conclusive experiments, which 
 were carried out both under natural and artificial con- 
 ditions by the British Plague Commission, and the work of 
 Verbijtski, which antedates the British Commission, were 
 presented, there has been no doubt that the transmission 
 of plague by blood-sucking insects, particularly by the 
 fleas, is one, although not the only, mode of spreading this 
 disease. It is obvious, as Herzog correctly remarks, that 
 the factors which are responsible for the spreading of 
 plague must be considered individually in each epidemic 
 and in various parts of the world as well. There is no 
 doubt that the importance of any insect in the trans- 
 mission of plague depends on its habits as well as on those 
 of the host, be it either animal or man. 
 
 During the recent outbreak of plague in Manila, sev- 
 eral samples of bed-bugs from the beds of the plague pa- 
 tients and dog fleas from a plagueinfected house were 
 collected and examined, but with negative result. 
 
 In spite of the fact that it adds nothing new to the 
 question of whether or not plague can be transmitted by 
 fleas, since the question has been conclusively answered 
 by the work of the Indian Commission, nevertheless the 
 following observations of a small outbreak of plague among 
 animals, the spreading of which was due solely to fleas, are 
 of interest. 
 
 One wild rat was inoculated with strain Iloilo 3 of 
 
140 PLAGUE 
 
 Bacillus pestis. The skin adjoining the root of the right 
 ear was scarified, and a loopful of the culture was smeared 
 on the scarified skin. The rat was found dead three days 
 after the inoculation. 
 
 The cage containing the dead rat was immersed in 
 kreolin solution. At autopsy the cervical glands were 
 found slightly swollen, somewhat reddened, but no haemor- 
 rhagic oedema of the surrounding tissue was noticeable. 
 There was slight necrosis at the place of inoculation, show- 
 ing superficial, purulent discharge. Clear effusion in both 
 pleural cavities and one hemorrhage in the pleura were 
 found. The lungs were hypersemic, but otherwise normal. 
 The spleen was of somewhat darker color, but otherwise 
 normal in size and appearance. The liver showed a slight 
 degree of parenchymatous degeneration, the congestion 
 making prominent the structure of the organ. The typ- 
 ical, although not constant, changes of the organ, which 
 are characteristic of natural plague infection in rats, were 
 absent. The kidneys were without macroscopic change. 
 The lymph glands, with exception of the cervical nodes, 
 were normal. 
 
 Examination of the rat's fur revealed ectoparasites 
 on the neck, under the chin, and back of the ears ; these 
 at the time of the examination apparently were dead. 
 About 6 common rat fleas were found and identified as 
 Lcemopsylla cheopis Rothsch. The parasites were im- 
 mersed in sterile salt solution for three hours. When re- 
 moved in a dry test tube, they began to move about slug- 
 gishly. The intestinal tract of these fleas contained blood. 
 
 Five of the fleas were crushed by means of sterile 
 forceps, and inserted in a pocket under the shaved skin 
 of a guinea-pig. The animal died of plague within three 
 days, showing considerable hemorrhagic oedema around 
 
ITS CONTROL AND SUPPRESSION 141 
 
 the place of inoculation, typical bilateral inguinal buboes, 
 and characteristic changes in the spleen. Smears and 
 cultures made from the bubo and spleen were positive for 
 Bacillus pestis. 
 
 Another wild rat, which was in a separate cage in the 
 same room where rat 1 had been kept, died twenty-four 
 hours after rat 1. The two cages were at least 10 centi- 
 metres apart. Rat 2 harbored fleas of the same species 
 as were found on rat 1. 
 
 Numerous severe bites were detected back of the ears 
 and on the neck of the dead animal. The post-mortem 
 findings were identical with those described in rat 1 ; that 
 is, cervix^al buboes, pleural effusion, and slightly enlarged 
 spleen. 
 
 It is well to remark that both rats had been kept in the 
 same room for about six months. Fleas had never been 
 noticed on our guinea-pigs. During the time the rats had 
 been kept in the plague house no irregular results were 
 noticed in plague-inoculated animals. At the time the 
 first rat was inoculated no other plague-infected animals 
 were in the plague house, and since that time another build- 
 ing has been used for plague-infected animals. 
 
 Two days after the death of rat 2 three guinea-pigs, 
 which were kept in separate cages in the same room, were 
 found dead of plague (smears and cultures were both 
 positive). Several fleas {Loemopsylla cheopis) were found 
 on the necks of these animals. They were collected and 
 inoculated in the same way as the fleas from the first rat. 
 The experimental animal, which was inoculated with the 
 fleas, was killed and found to be infected with plague. 
 The findings were local reaction, inguinal buboes, and 
 typical spleen. Smears and cultures were positive for 
 Bacillus pestis. 
 
142 PLAGUE 
 
 Although numerous healthy guinea-pigs were ex- 
 amined in the same plague house, no fleas could be found 
 at that time, only the 2 rats and the first 3 guinea-pigs 
 are positively known to have harbored fleas, the latter 
 after the death of the rats and not before. 
 
 The gross lesions in these naturally infected guinea- 
 pigs were somewhat unlike those found in guinea-pigs in- 
 fected either by vaccination or by intraperitoneal or sub- 
 cutaneous inoculation. All except one showed primary 
 buboes on the neck with more or less extensive hemorrhagic 
 oedema extending in some cases over the thorax. There 
 was little pleural effusion present; the spleen always 
 showed typical changes of necrotic foci varying in size 
 and number. In one instance similar foci were found also 
 in the liver, large enough to be visible macroscopically. 
 This was in a case where like changes were found in the 
 lungs. 
 
 Only one of the guinea-pigs showed an exception, in 
 that the primary buboes were located in the inguinal 
 region, with pelvic and axillary glands secondarily in- 
 volved. These are the findings usually met with in guinea- 
 pigs artificially infected with plague by the vaccination 
 method, if the lower part of the abdomen be chosen for 
 inoculation. The reason for such a deviation from the 
 findings in the rest of the guinea-pigs may lie in the fact 
 that this animal was almost completely deprived of hair 
 by a skin disease. 
 
 It is of importance to mention the skin lesions which 
 were found on the necks of the guinea-pigs, particularly 
 under the chin. Besides small red spots which appeared 
 to be fresh flea bites, small, elevated, and fairly deep in- 
 filtrations partly covered with moist scab were found in 
 the skin under the chin. Other animals showed changes 
 
ITS CONTROL AND SUPPRESSION 143 
 
 usually found in the scarified skin of guinea-pigs after 
 artificial inoculation with plague material. The base of 
 each cutaneous efilorescence was hemorrhagic and (Ede- 
 matous. 
 
 A histological study of the tissues of these guinea-pigs 
 known to be naturally infected by plague fleas showed the 
 following changes : 
 
 The Cervical Bvbo. — The enlarged lymphatic gland 
 was surrounded with a thickened capsule. Necrosis ex- 
 isted in the subcapsular part of the gland, where it formed 
 an almost continuous circular zone, leaving the central 
 part less changed. Smaller irregular necrotic foci were 
 scattered throughout the section. Polymorphonuclears in 
 various stages of disintegration were found throughout the 
 section. 
 
 The Lungs. — Very few blood extravasations were pres- 
 ent in the alveoli; otherwise normal. 
 
 The Spleen. — The capsule was thin. There were sub- 
 capsular hemorrhages. The Malpighian bodies were 
 somewhat enlarged, but of normal structure. Throughout 
 the parenchyma irregiilar multiple necrotic foci were 
 found, leaving but little of spleen tissue intact. Numer- 
 ous polymorphonuclears which were present showed vary- 
 ing degrees of karyorrhexis. 
 
 The Kidneys. — The outline of the cells was indefinite ; 
 a few miliary hemorrhages existed in the cortical part of 
 the organ. 
 
 The Liver. — There was excessive congestion, fatty de- 
 generation, and pigmentation of the cells. The capsule 
 was slightly thickened. 
 
 The Skin. — The epithelium was missing in one place 
 in the section, and cellular infiltration extended from that 
 place into the subepithelial layer of the surrounding skin. 
 
144 PLAGUE 
 
 The same kind of infiltration reached deep into the skin, 
 stripes of cellular infiltration penetrating into the tissue 
 along the muscle fibres. There was no direct connection 
 between the cellular infiltration and the follicles of the 
 hair. 
 
 It may be well to describe in detail the time of death 
 from plague among these and the other animals in this out- 
 break, as well as the time when the plague house was 
 disinfected. 
 
 The first animal (rat 1) having been inoculated on 
 August 27, in the afternoon, died of plague within three 
 days (August 30). The second animal (rat 2) died 
 twenty-four hours later. Guinea-pigs S, 4, and 5 (see 
 plan) were found dead on the morning of September 2; 
 that is, two days after the death of rat 2 and three days 
 after the death of rat 1. 
 
 The same day that the three guinea-pigs were found 
 dead of plague, rooms I, III, IV, and VI were thoroughly 
 disinfected. The floor, the ceiling, and the walls were 
 sprayed with kerosene and lysol solution. The remaining 
 animals in room VI were destroyed, and the cages disin- 
 fected. No animals were kept in rooms I, III, and IV at 
 that time. 
 
 Three days after the death of animal 5, guinea-pigs 
 6 and 7 were found dead of plague, while the next day 
 guinea-pigs 8 and 9 died. No death occurred on Septem- 
 ber 7, but the next two days each recorded two plague 
 guinea-pigs (10, 11, 12, and 13). On September 11, the 
 last guinea-pig died of plague in this outbreak. The 
 whole building was then thoroughly disinfected. No 
 plague-inoculated animals were kept in the rooms after 
 the first sign of the epidemic. After September 11, no 
 more cases of spontaneous plague infection were observed. 
 
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ITS CONTROL AND SUPPRESSION 145 
 
 It will be noticed that the epidemic lasted eleven days 
 after the first animal died and fourteen days after animal 1 
 was inoculated. Altogether, 14j animals out of at least 
 200 animals exposed died of plague. 
 
 No death occurred among rabbits, although these 
 animals were distributed among the guinea-pigs. In fact, 
 2 rabbits were surrounded by plague guinea-pigs 8, 9, 
 and 10, but did not contract plague. 
 
 From the epidemiological -standpoint it is interesting 
 to know the dimensions and location of the cages in which 
 the animals were kept. 
 
 Aside from the 2 rats which were confined in ordinary 
 traps that stood on a table 80 centimetres high, the rest 
 of the animals were kept in regular metal animal cages. 
 The dimensions of the cages are: Fifty centimetres long, 
 36 centimetres broad, and 30 centimetres high. The cage 
 stands on four legs each 10 centimetres long; the centre 
 of the b^ .tom of the cage holds a drain opening 8 centi- 
 metres above the floor. 
 
 The majority of the cages in room II were located 
 on the floor ; some on the second shelf of a wooden rack. 
 This last-mentioned arrangement, judging from the con- 
 struction of the wooden frame, allowed a continuous pas- 
 sageway for the fleas to the second shelf of the racks. 
 On the other hand, the deaths among the guinea-pigs in 
 room V were restricted to the cages standing on the floor, 
 the majority of cages in that room being placed on tables 
 80 centimetres high. 
 
 Only a theoretical explanation can be given of the short 
 duration and sudden cessation of the outbreak. One can 
 assume with great probabiHty that the first partial dis- 
 infection drove the fleas away from the primary source 
 of infection, and that they traveled as far as possible. 
 10 
 
146 PLAGUE 
 
 The}^ finally settled in those guinea-pig cages which had 
 not been molested by the first disinfection. Having no 
 new supply of plague blood (all of the plague-infected 
 guinea-pigs having been removed, most of them before 
 death), the fleas soon cleared themselves of plague bacilli. 
 The peculiar feature of the outbreak, namely, the failure 
 to find fleas on the animals in rooms II and V, finds its 
 explanation in the observation of the Indian Commission 
 who found that the fleas " died or disappeared very 
 rapidly." 
 
 The following conclusions can be drawn from these 
 observations : 
 
 1. The common rat flea {Loemopsylla cheopis) pre- 
 fers the rat to the guinea-pig. 
 
 2. In the absence of rats it will attack guinea-pigs 
 rather than rabbits, 
 
 3. The fleas which have sucked blood from rats or 
 guinea-pigs afflicted with plague septicaemia were found to 
 harbor virulent plague bacilli inside of their bodies. 
 
 4. The transmission of plague infection by direct or 
 indirect contact being excluded in our case, the fact that 
 fleas of the same species and harboring plague bacilli were 
 found on the rat and on the guinea-pigs, the presence of 
 flea bites on the rats and on the guinea-pigs with positive 
 findings of skin lesions on that part of the body where the 
 fleas and flea bites were located, together with the anatom- 
 ical picture of the findings in the guinea-pigs, lead to but 
 one explanation ; namely, that the plague infection was 
 transmitted by fleas. 
 
 III. Obsekvations on Animals Suspected of Plague 
 
 Out of the several tens of thousands of rodents ex- 
 amined during the antirat campaign, we have found only 
 
ITS CONTROL AND SUPPRESSION 147 
 
 two plague rats which showed the typical picture of 
 natural plague infection in rat; that is, cervical buboes 
 with surrounding oedema, subcutaneous injection, pleural 
 eifusion, enlarged spleen, and such changes of the liver as 
 are characteristic of natural plague infection in rats. 
 Microscopically, large numbers of plague bacilli were 
 found in these cases, and pure cultures of Bacillus pestis 
 were recovered from the spleen. Histological examination 
 of internal organs, particularly that of the liver, con- 
 firmed the bacteriological findings. The remainder of the 
 plague rats exhibited only two of the signs of plague 
 infection, namely, bubo and oedema of the surrounding 
 tissue,.and eventually hemorrhages. 
 
 Besides plague infection, a great number of rats 
 showed purulent conditions from causes other than plague. 
 Abscesses of the lungs were frequently met with, and cer- 
 vical or axillary buboes are not uncommon in Manila rats. 
 Various pyogenic bacteria were found in the pus of such 
 abscesses. Of the less common was Bacillus pyocyaneus 
 and the pneumobacillus of Friedlander. Chronic plague 
 was excluded in these cases since the animal inoculation 
 failed to produce plague infection. 
 
 More than half of the rats examined harbored para- 
 sites in their organs. EcJiino coccus teniceformis was 
 found in the liver of practically every gray rat, while a 
 small Ascaris and Tcenia diminuta were not uncommon in 
 the intestines. Two rats were found to have sarcosporidi- 
 osis, 2.6 per cent, showed rat leprosy, and 7.4 per cent, 
 trypanosomiasis. One tumor of the mammary gland and 
 one tumor in the axillary region were encountered, while 
 one tumor of the large curvature of the stomach proved 
 to be a chronic inflammatory tumor due to parasites. One 
 peritoneal tumor in a rat (Mus decumanus) gave the im- 
 
148 PLAGUE 
 
 pression of a malignant tumor on account of the miliary 
 dissemination of the peritoneum. It was found to consist 
 of muscle and spindle-cell sarcomatous tissue. Ectopara- 
 sites were very seldom noticed, on account of the method 
 of collecting the rats. When present, they were mites 
 and fleas. 
 
 In the naturally infected plague rats the rigidity of 
 the fresh cadaver was pronounced. The primary bubo 
 was in every case cervical. Cervical glands were enlarged 
 and hemorrhagic with sHght oedema of the surrounding 
 tissue. The subcutaneous injection extended over the 
 neck and chest. The inguinal glands were small and pig- 
 mented. The lungs were collapsed, and showed hemor- 
 rhagic foci. The spleen was slightly enlarged, firm, and 
 dark red. The liver was rather large, firm, pale red, 
 with shade of yellow, which was caused by minute yellow- 
 ish foci thickly scattered throughout the tissue and visible 
 through the capsule. The kidneys were hypersemic. The 
 intestiries were without change. The serous membranes 
 were pale with no hemorrhages. 
 
 Histological examination of the tissue of naturally 
 infected plague rats showed the following changes : 
 
 Liver. — The structure of the organ was well marked; 
 the veins dilated, trabeculse slightly compressed, nuclei 
 well stained, and few of the liver cells showed vacuoles. 
 Small foci, most numerous under Glisson's capsule, were 
 scattered throughout the organ ; they varied in size, but 
 were not larger than a miliary tubercle. The small ne- 
 crotic foci were found to consist of few necrotic liver cells. 
 The centre of the larger foci was formed by degenerated 
 and necrotic liver tissue, surrounded by round-cell infil- 
 tration. Polymorphonuclears were also found in the zone 
 of cellular infiltration. There was a slight degree of 
 
ITS CONTROL AND SUPPRESSION 149 
 
 hemorrhage in each focus. Epithelioid cells and large 
 vesicular cells with several nuclei were to be found. The 
 foci, mentioned above, were sharply demarcated from the 
 surrounding liver tissue, which appeared to be intact. 
 
 Spleen. — The structure was well preserved, the capsule 
 thin. The Malpighian bodies were normal as to the ele- 
 ments of wliich they consist. Cells with pycnotic nuclei 
 were scattered throughout the organ, and vesicular cells 
 with small, deeply stained, excentrically located nuclei 
 were present. Polymorphonuclears were found in the 
 tissue in considerable numbers. No localized necrotic foci 
 could be found in sections through the spleen. 
 
 Cervical Glands. — The blood-vessels were considerably 
 distended. A few hemorrhages and polymorphonuclears 
 were present. CEdema of the capsules and surrounding 
 tissue existed. Part of the gland was necrotic. 
 
 Lungs. — The blood-vessels were distended. The alveoli 
 contained homogeneous masses and blood. There were 
 numerous subpleural hemorrhages. The bronchi were col- 
 lapsed, and contained mucus. 
 
 Kidneys. — The cortical part showed subdued struct- 
 ure; the epithelial cells had an indefinite outKne and occa- 
 sionally showed vacuolization. The medullar part was 
 better preserved. There were miliary subcapsular hemor- 
 rhages. A few small foci were scattered throughout both 
 medullar and cortical parts. They consisted of round-cell 
 infiltration. 
 
 Natural Plague Infection in a Cat 
 
 The experiments of the German Plague Commission 
 proved that cats showed considerable resistance to plague 
 infection as cutaneous and subcutaneous inoculations 
 failed to infect them. According to the Austrian Com- 
 
150 PLAGUE 
 
 mission, cats develop submaxillary buboes if fed on plague 
 material. They are said by Albrecht and Gohn ^^ some- 
 times to recover. Out of four cats fed on plague material 
 two died of plague, one showing submaxiLlary, the other 
 mesenterial buboes. Virulent plague bacilli were found 
 in the discharge from the nose and also in the faeces of 
 cats which apparently did not become infected after hav- 
 ing been fed on plague material. 
 
 One case of spontaneous plague infection of a cat was 
 recorded by Thompson ^^ in Sydney. 
 
 W. Hunter,-"-^ in Hongkong made observations on cats 
 suffering from plague infection. The author also under- 
 took a few experiments, and arrived at the following 
 conclusions : 
 
 1. Cats suffer from plague. 
 
 2. The disease may be acute or chronic. 
 
 3. The type of the disease is septicaemic. 
 
 4. The animals may occasionally play a part In the 
 dissemination of plague. 
 
 5. In plague-infected areas cats probably become in- 
 fected through rats, which they devour as food. 
 
 6. In plague-infected districts possible plague infec- 
 tion in cats is of great importance from a domestic point 
 of view. 
 
 On November 27, 1912, a sick cat was brought to the 
 laboratory for examination. It was reported that the 
 animal was found in a warehouse in which dead rats had 
 
 ^^ Uber die Beulenpest in Bombay im Jahre 1897 (189?), 
 II B, II C. 
 
 ^- Report of an outbreak in Sydney, 1900. Referred to 
 in Kolle and Wassermann (1903), 2, 510. 
 
 "Lancet (1905), I, 106i. 
 
ITS CONTROL AND SUPPRESSION 151 
 
 been found some time previously. The rats were not 
 examined. In the morning of the 30th, the cat was found 
 dead in the cage where it had been kept under observation. 
 The following are the post-mortem findings : 
 
 The animal was a fairly well-nourished female. ^^ The 
 subcutaneous tissue, pericardium, mediastinum, and mesen- 
 terium contained considerable amounts of fat. 
 
 The subcutaneous tissue of the neck showed oedema and 
 small hemorrhages. The submaxillary tissues were swol- 
 len on both sides. When the fascise and superficial muscles 
 of the neck were removed, enlarged glands were found on 
 both sides. These were closely attached to the submaxil- 
 lary salivary glands. The surrounding tissue was oedemat- 
 ous, but no hemorrhages were noticed in the vicinity of 
 the enlarged glands. Upon section the glands were found 
 to be necrotic, and upon pressure a thin purulent liquid 
 escaped. There were no hemorrhages within the glands. 
 Several enlarged lymph-nodes, smaller in size, could be 
 followed down the neck on the left side. The lymph-nodes 
 in the axillae as well as in the groins and peribronchial 
 nodes were normal. The mesenteric glands were slightly 
 enlarged and reddened. 
 
 The lungs were slightly collapsed. A clear, sanguin- 
 eous, slightly coagulated effusion was observed in both 
 pleural cavities. The tissue of the lungs showed con- 
 siderable oedema and hypostasis. The bronchi and 
 pharynx showed no changes, the mucous membrane being 
 pale and thin. 
 
 ^* The cat was the mother of 4 kittens which were about 
 3 weeks old at the time the cat was delivered for examination. 
 They were kept under observation for several weeks, but 
 showed no signs of plague infection. 
 
152 PLAGUE 
 
 The heart was normal. 
 
 The spleen was enlarged, of light red color, with fol- 
 licles slightly prominent. 
 
 The stomach contents was blackish in color ; there were 
 no hemorrhages or ulcers in the mucosa. 
 
 The liver was somewhat enlarged. The organ showed 
 prominent structure, the centres of the acini being red, 
 the periphery lighter in color. 
 
 The kidneys were slightly enlarged and pale. The 
 capsule peeled off easily, the vense stellatse were prominent, 
 the surface smooth; there were no hemorrhages. The 
 cortex was increased in breadth and was of the same 
 color as the surface; the pyramids were darker in color. 
 The organ was of fragile consistence. 
 
 Suprarenals were normal, as were also intestine and 
 bladder. 
 
 The histological findings were as follows : 
 
 Bubo. — The capsule of the gland was oedematous. The 
 whole gland as seen in cross section had undergone necro- 
 sis, except a few foci which still showed cellular structure. 
 
 Lungs. — The alveoli were filled with homogeneous 
 masses, containing but few degenerated epithelial cells and 
 leucocytes. The blood-vessels were dilated, particularly 
 in the subpleural part of the organ. In some places capil- 
 lary mycotic emboli with subsequent hemorrhage were 
 encountered. The large blood-vessels and bronchi were 
 normal. 
 
 Salivary Glands. — Those glands attached to the pri- 
 mary bubo showed the normal structure of a combined 
 mucous and serous gland. 
 
 Liver. — There was considerable congestion. The 
 centres of the acini showed parenchymatous and fatty 
 degeneration. The cells on the periphery of the acini 
 
ITS CONTROL AND SUPPRESSION 153 
 
 exhibited typical fatty infiltration. The large blood-ves- 
 sels and small ducts were without change. 
 
 Kidney. — The cells of the kidney showed various de- 
 grees of degeneration, ranging from parenchymatous to 
 fatty infiltration. There were a few capillary hemor- 
 rhages and hyaline casts present. 
 
 Suprarenals. — These showed slight degeneration. 
 
 Spleen. — This organ showed congestion, a few hemor- 
 rhages, and bacterial emboli; otherwise normal. 
 
 The bacteriological examination of the material from 
 this cat gave the following results: 
 
 1. Smears: 
 
 a. From the buboes showed degenerated leucocytes, 
 
 many lymphocytes, and numerous bacteria, 
 some of which resembled Bacillus pestis in their 
 polar staining. 
 
 b. From the spleen showed numerous plague-like, 
 
 polar-stained bacilli. Round involution forms 
 were present. 
 
 2. Cultures: 
 
 a. From the buboes were badly contaminated with 
 Bacillus coli and Bacillus pyocyaneus colonies. 
 
 h. From the spleen : A few scattered colonies of Bacil- 
 lus pyocyaneus developed on the surface of the 
 agar. Between the large colonies a scanty 
 growth of dewy appearance was noticed. Smears 
 made from this growth revealed plague-like 
 bacilli of the cultural type, showing a few club- 
 shaped involution forms. Subcultures were 
 made in order to secure pure culture. They 
 showed a pure growth of Bacillus pestis as in- 
 dicated by the morphology of bacilH and shape 
 of the colonies. Agglutination with plague-im- 
 mune serum was positive. 
 
154 PLAGUE 
 
 3. Inoculation experiments {vaccination method): 
 
 a. One guinea-pig was inoculated with the material 
 from the left bubo, another one with material 
 from the right bubo. They died of plague on 
 the tliird and fifth days, respectively. 
 h. One guinea-pig was inoculated with the material 
 from the spleen. It died of plague on the tliird 
 day. 
 
 c. One guinea-pig was inoculated with material from 
 
 the nostrils obtained by swab. The animal sur- 
 vived, showing no indication of plague. 
 
 d. One guinea-pig was inoculated with material from 
 
 the rectum obtained by swab. It died of plague 
 on the fifth day. 
 
 Although plague infection among cats is apparently 
 a rare occurrence, the fact that cats may contract the 
 disease in spite of the high degree of resistance to plague 
 infection has to be considered from the hygienic stand- 
 point. 
 
 To appreciate the important role which cats may play 
 in the spreading of the disease one need only consider the 
 close contact of these animals with rats on one side and 
 human beings on the other. It is also a well-established 
 fact that not only plague-infected cats, but also those 
 which have devoured plague-infected material and re- 
 mained apparently normal, may excrete plague bacilli 
 which have retained their full virulence. 
 
 ^^OTEs ON Plague in Hong Kong by Dr. 
 RoBERG. — During the Hong Kong epidemic of 
 plague which preceded and was coincident with that 
 
ITSICONTROL AND SUPPRESSION 155 
 
 of Manila, I visited that city twice (December, 
 1913, and July, 1914), but I did not closely in- 
 vestigate the methods adopted and carried out by 
 the authorities there, for the reason that the Manila 
 plan was so much more productive of results, as 
 shown by the apparent inability of the Hong Kong 
 officials to gain control of the disease. However, 
 I received from Dr. David Roberg, of the Oregon 
 State Board of Health, a copy of a report made 
 by him to the Secretary of his State Board of 
 Health, following an investigation of the Hong 
 Kong epidemic and the methods there followed. 
 I have Dr. Roberg's permission to use his report 
 and it is herewith presented. It is dated Manila, 
 April 16, 1914, and is as foUows: 
 
 I have the following notes to present on the epidemic 
 of bubonic plague in Hongkong. 
 
 On April 5th when I arrived in Hongkong the epi- 
 demic was rapidly approaching its height. With its onset 
 in January there were 47 cases, in February 42, and in 
 March 223. During the week previous to April 5th, there 
 were 91 cases ; during the six days I was in Hongkong 
 they averaged 15 a day. 
 
 Judging from previous epidemics the present one will 
 be exceptionally severe. The season for the occurrence of 
 human plague is from the months of February to July. 
 
156 PLAGUE 
 
 The onset is gradual ; in May it reaches its maximum and 
 then declines. In the epidemic of 1912, for the city of 
 Victoria the monthly rate showed the following, January 9, 
 February 22, March 61, April 265, May 513, June 346, 
 July 105, August 11, and September 1. Comparing these 
 rates with those of the present year it will be seen that 
 the number for March far exceeds that of two years 
 previous. 
 
 Illustrating the season for human plague, with its on- 
 set, maximum and decline, are the monthly rates for the 
 city of Kowloon during 1912, when the following cases 
 occurred: February 2, March 12, April 52, May 246, 
 June 152, July 39, August 8, and September 3. 
 
 The season for human cases is determined by the con- 
 dition of the rats. At the close of the season in July the 
 rats die off from plague in great numbers as it is then the 
 hottest time of the year. During the months from Sep- 
 tember to February the rats increase in number and in 
 susceptibility to the extent of being sufficient to again 
 infect human beings. Moreover every other year shows a 
 marked severity in the epidemics of human bubonic plague. 
 This is explained by the fact that it requires two years' 
 time for the rat population to become of sufficient great- 
 ness and susceptibility to cause a severe human outbreak. 
 This is shown by the yearly number of cases since the year 
 1911. During the years 1911, 1912 and 1913 respec- 
 tively, there were 253, 1847, and 408 cases. During the 
 present year the monthly rate is exceeding that of the 
 heavy year of 1912. 
 
 The severe epidemic in 1912 was a result of the influx 
 of 50,000 Chinese refugees into Hongkong during the 
 revolution in 1911. The number of rats in the native 
 
ITS CONTROL AND SUPPRESSION 157 
 
 district depends upon the available food supply, and as 
 a result of this human overcrowding the amount of waste 
 food so increased in the houses, yards and streets, that the 
 over accumulation of garbage could not be kept pace with. 
 This influx also brought in great numbers of susceptible 
 rats. 
 
 The number of rats killed off during the epidemic in 
 1912 were so great that in 1913 they had not recovered 
 sufficiently to cause a severe outbreak during that year, 
 and as a result of the lightness of epidemic in 1913, they 
 are so increased in number and susceptibility now that they 
 are causing a very severe epidemic in human beings. 
 
 Of rats in Hongkong they have the Mus decumanus 
 or drain rat and the Mus rattus or house rat. It is note- 
 worthy that the drain rat is found plague-infected 
 throughout the year, while the house rat is found infected 
 only during the period in which the human epidemics occur, 
 namely from February to July. The number of infected 
 rats a year run parallel to the number of monthly cases. 
 
 The bulk of human infection is due to the spread of 
 house rats. Man also becomes infected by the drain rat 
 when the drains are flooded by rain storms and the rats 
 are driven into the houses. 
 
 What has made plague permanent in Hongkong is the 
 overcrowding of the native districts. Besides there is a 
 floating population entering and leaving the native quar- 
 ters, numbering about 4000 a day. The native houses 
 have been built with double floors and walls wliich harbor 
 the rats. Where the construction is of wood it is pos- 
 sible to remove the rat spaces. It has been found since 
 the introduction of plague into Hongkong in 1894, that 
 those districts containing the greatest number of soft 
 
158 PLAGUE 
 
 brick houses with hollow walls, have shown the greatest 
 incidence of plague. This can not be remedied as it would 
 involve the destruction of buildings on too large a scale. 
 
 The Woek of the Sanitaky Boaed 
 
 The area under the control of the Board comprises 
 the Island of Hongkong containing 32 square miles, with 
 a sea frontage of 13 miles in length. Included also is the 
 old city of Kowloon which is situated one mile and a third 
 across the harbor and contains two and three-fourths 
 square miles. The city of Victoria on the northern shore 
 of the Island of Hongkong has a sea frontage of 5 miles, 
 contains about ten thousand domestic buildings, of which 
 about one thousand are non-Chinese. 
 
 The population of Hongkong is difficult to estimate, 
 as the floating population is so great. In the 1912 census 
 there were 446,614 Chinese and 21,163 non-Chinese. 
 
 The city of Victoria is divided into 10 Urban Health 
 Districts and old Kowloon into 2. There is an inspector 
 in charge of each. These districts are built over an area 
 averaging from 31 to 140 acres. The houses in these dis- 
 tricts average one thousand and the population from 8000 
 to 33,000. There are four inspectors in charge of the 
 scavenging work, one for the disinfection stations in Vic- 
 toria and old Kowloon, one for the cemeteries and two 
 for general duty. 
 
 The measures employed by the Sanitary Board are 
 summarized as follows : 
 
 1. The exclusion of rats from all dwellings by means 
 of concreted ground surfaces, the protection of all drain 
 
ITS CONTROL AND SUPPRESSION 159 
 
 openings and ventilating openings by iron gratings, and 
 the prohibition of ceilings and of hollow walls in new build- 
 ings and in those existing buildings from which they have 
 been removed by order. 
 
 2. The collection and bacteriological examination of 
 all dead rats. Facilities for the collection of rats in the 
 quarters are provided in the shape of small covered bins 
 attached to lamp posts, telephone posts, electric light 
 poles, etc. These bins contain a carbolic acid disinfectant, 
 and the inhabitants are invited to at once put into them 
 all rats found or killed by them. There are 650 of these 
 bins distributed throughout the city and its suburbs, and 
 each of them is visited twice daily by rat collectors who 
 take all rats found by themi to the City Bacteriologist. 
 Each rat is at once labelled with the number of the bin 
 from which it is taken, and if subsequently found to be 
 plague infected, a special survey is immediately made of 
 the block of houses in that vicinity. All rat-holes and 
 rat runs are filled up with broken glass and cement, de- 
 fective gratings and drains dealt with, and rat poison 
 distributed free to the occupants. If several plague- 
 infected rats are found in one locality, a special house-to- 
 house survey and cleansing of that district is made. 
 
 3. The destruction of rats by poison, traps and bird- 
 lime boards; special efforts in this direction being made 
 just before the onset of the regular plague season which 
 is in the months of from March to July. 
 
 4*. The encouraging of the community to keep cats. 
 
 5. The systematic cleaning and washing out of all 
 native dwellings at least once in three months with a flea- 
 killing mixture made by emulsifying kerosene in water. 
 
 6. An efiicient daily scavenging of all streets and lanes 
 
160 PLAGUE 
 
 and the daily removal of refuse from the houses, coupled 
 with the provision of covered metal dust-hins, to reduce as 
 far as possible the amount of food available for rats. 
 
 7. The disinfection of plague-infected premises by 
 stripping them and washing them out thoroughly with a 
 kerosene emulsion. The bedding, clothing, carpets, rugs, 
 etc., are conveyed in a huge covered basket to the disin- 
 fecting plant and steriHzed with superheated steam. No 
 objection is made to the treatment of plague cases in 
 native hospitals, and no restrictions are imposed in regard 
 to the burial of those dead with plague except the pro- 
 vision of a substantial cofBn. 
 
 8. Every effort is made by means of lectures, ad- 
 dresses and explanations to induce the native population 
 to participate in the above preventive measures. 
 
 Upon my last visit to Hong Kong, in July last, 
 plague was abating. The South China Morning 
 Post of July 15, 1914, contained the following 
 statement : 
 
 Plague is gradually disappearing from Hongkong. 
 Last week's return shows that there were 26 cases, of 
 which 19 were fatal. All were Chinese. The total number 
 of cases for the current year to date is 2093, with 1939 
 deaths resulting. 
 
 I regret that circumstances do not permit me 
 to relate in detail the work done and the observa- 
 tions made during the closing six months of the 
 Manila epidemic. 
 
ITS CONTROL AND SUPPRESSION 161 
 
 Up to the day of my departure from the PhiUp- 
 pines, in July, 1914, 1 remained in charge of plague 
 suppression, but the added duties of administra- 
 tion at San Lazaro Hospital and the coincident 
 occurrence of a cholera epidemic prevented me from 
 keeping a detailed record in such form as to per- 
 mit reproduction here. It will therefore' suffice 
 to say that the first six months of 1914 witnessed 
 the passing of the most threatening situation that 
 has confronted the city of Manila in years. The 
 record of plague rats found does not convey an 
 accurate idea of the prevalence of rat plague by 
 any means, for the simple reason that, when found, 
 the rat cadavers were in such condition as to forbid 
 bacteriologic examination; and inasmuch as the 
 bacteriologic test of plague had been used exclu- 
 sively in determining rat plague up to this time, it 
 seemed desirable to adhere to the original method. 
 
 In February we found in one of the districts, 
 in which we undertook systematic work in conse- 
 quence of a few cases of human plague, a very 
 large number of dead rats, in and adjacent to 
 houses which furnished human plague cases. In 
 
 one building alone more than 150 rat cadavers were 
 11 
 
162 PLAGUE 
 
 found during our cleaning and rat-proofing opera- 
 tions. It is this district concerning which the letter 
 to the public (already quoted) was written. 
 
 The methods followed in treating this new and 
 dangerous focus of infection did not differ from 
 those practised during the previous year, except 
 in the matter of intensity. Forces of the cleaning 
 and rat-catching gangs were increased and the ut- 
 most thoroughness of treatment was insisted upon. 
 The results fully justified our policy and demon- 
 strated again how feasible it is to fight plague suc- 
 cessfully if adequate authority be given. 
 
 During the last year of the epidemic in Manila 
 it became the rule for us to expect our plague 
 workers to locate and find the identical rat cadaver 
 from which the infected fleas bore the disease to 
 the hmnan victim, provided the spot upon the floor 
 where the patient's sleeping mat had been placed 
 was known. In the better class of houses the rat 
 (sometimes more than one) was found dead be- 
 neath the floor, behind some post casing, or in other 
 space caused by double construction. Time and 
 again I have directed the removal of some panel of 
 woodwork, some post casing, or a board of the floor 
 
ITS CONTROL AND SUPPRESSION 163 
 
 with the full expectation (seldom unrealized) of 
 finding a dead rat or a rat nest. These experiences 
 were positively uncanny at times. In the houses of 
 the poorer class, usually of bamboo and thatch con- 
 struction, the finding of the rat was less easy and 
 more uncertain, although the nest was repeatedly 
 fomid, and as related elsewhere the dead rat itself 
 might be found in a hollow bamboo timber, or in 
 the thatch construction of the wall. In a house on 
 Calle Echague, from which a Fihpino and his wife 
 were removed, dead, within a few hours of each 
 other, several dead rats were found in the floor 
 (the only piece of double construction in the whole 
 house) within four feet from the spot where the 
 sleeping mats were placed. A rat hole led to the 
 nest and through this hole the fleas from the dead 
 rats found their way to the human victims sleeping 
 on the floor above the encased nest. 
 
 These instances could be multiplied many times, 
 but there is no longer any special reason to do so, 
 as the rat and the rat-flea are so completely in- 
 criminated as to render these repetitions quite un- 
 necessary, however interesting they may be to the 
 plague worker. The danger of pursuing these in- 
 
164 PLAGUE 
 
 vestigations, to the persons so engaged, must not 
 be lost sight of, and exposure of such nests and rat 
 cadavers should invariably be preceded by thor- 
 ough spraying of the place, and particularly of 
 the spot where tearing out of double construction 
 is to be done. I know of no more dangerous em- 
 ployment than this, both for laborer and bystander. 
 
CHAPTER IV 
 
 ITS DIAGNOSIS AND TREATMENT 
 
 It was not my original intention to include the 
 subjects of diagnosis and treatment in this presen- 
 tation, except in so far as I have already referred 
 to them in the relation of my Manila experiences 
 in the preceding pages. I have decided, however, 
 to add a chapter upon Diagnosis and Treatment, 
 for the sake of completeness. No attempt will be 
 made to present these subjects in the orthodox way. 
 
 Rather, my remarks will be confined to such 
 matter as I believe to be thoroughly practical and 
 relevant. 
 
 In my opinion, the day has arrived when we 
 may properly exclude from such handbooks as this 
 one (intended for practical guidance), all such 
 methods of diagnosis and treatment as have failed 
 to meet the test of actual experience through a 
 reasonable length of time. Twice in recent years,^ 
 I have described the diagnosis and treatment of 
 
 ^ Tropical Medicine (1907) and Hare's Modern Treat- 
 ment (1911), vol. 1. 
 
 165 
 
166 PLAGUE 
 
 plague, attempting in each case to present a reason- 
 ably full account of the methods employed and 
 advocated by authorities, for theoretic reasons and 
 from the recorded personal experiences of medical 
 men tliroughout the world. There comes a time, 
 however, when wheat and chaff must be separated 
 and when methods which have failed, in application, 
 to justify preformed expectations must be rele- 
 gated to the department of historical medicine. 
 
 Judging from recent medical text books it is 
 evident that medical writers are generally accept- 
 ing this view as the proper one. At any rate, my 
 experiences and those of my medical friends during 
 the Manila epidemic of 1912-1914, have led me to 
 discard as impracticable, unproven, disproven or 
 unpromising, certain plans of treatment formerly 
 deemed worthy of trial. I do not refer to these 
 methods individually but will content myself, in- 
 stead, with reciting briefly the methods which I 
 believe, from personal experience and the collected 
 experience of others, to be worthy of continuance 
 and of further trial. 
 
 Diagnosis. — The rapid diagnosis of plague is 
 always of the utmost importance, both from the 
 view-point of prognosis and treatment, in the in- 
 
ITS DIAGNOSIS AND TREATMENT 167 
 
 dividual case, and from the community view-point 
 of the recognition of the presence of a dangerous 
 communicable disease, with the resultant obhgation 
 falhng upon the health authorities. 
 
 The Biologic Diagnosis. — Let us understand, 
 first and finally, that but one diagnosis is absolutely 
 and irrefutably dependable, viz. : the biologic diag- 
 nosis. Herein I would include not only the recov- 
 ery of the pest bacillus from the patient, but the 
 recovery and identification of the organism from 
 inoculated animals, infected from blood, tissues, 
 secretions or cultivated plague bacilh derived from 
 the human patient or cadaver. 
 
 This entire process involves a lapse of time of 
 several days, and, while it is indispensable in the 
 earliest cases of an epidemic, and highly desirable 
 for the proper study of aU cases of plague, it is 
 impracticable and unnecessary, in communities 
 where plague is known to exist, to carry out more 
 than the first steps of the biologic diagnosis, viz.: 
 the recovery of B. pestis (morphologic identifica- 
 tion) from the patient. 
 
 Necessity for Trained Bacteriologist. — It 
 is evident that the services of a trained bacteri- 
 ologist are indispensable in the accurate diagnosis 
 
168 PLAGUE 
 
 of plague, unless (as rarely is the case) the ob- 
 server himself is both clinician and bacteriologist. 
 Even in this case it is far better for two persons, 
 clinician and bacteriologist, to work together. I 
 will not discuss the technic of the procedures of 
 biologic diagnosis, which is described by Dr. Schobl 
 in the preceding pages. Except under circum- 
 stances of necessity, the clinician should always 
 turn this work over to the bacteriologist. 
 
 Serum reactions, when present, occur too late 
 to be of service in practical diagnosis. 
 
 The necessary procedm-es of the biologic diag- 
 nosis include blood-culture, smear examination 
 (microscopic) of aspirated material from the 
 oedematous tissues surrounding gland masses and 
 from glands themselves; examination of sputum 
 smears and of thick-blood smears. 
 
 All should be practised but, according to our 
 Manila experiences, smear examinations of as- 
 pirated material and blood cultures are the most 
 reliable methods, in the hands of a competent bac- 
 teriologist. Attention is invited to the reports of 
 Dr. Otto Schobl, already quoted. 
 
 Bacteriologic Procedure. — ^Dr. Schobl was 
 able to secure positive blood cultures, within 24 
 
ITS DIAGNOSIS AND TREATMENT 169 
 
 hours, from all of a long series of cases of plague, 
 both bubonic and septicasmic. As much blood as 
 it was possible to secure was aspirated from super- 
 ficial veins and introduced into the culture media 
 at the bedside, ten c.c. being secured whenever it 
 was possible. 
 
 The smear preparations for staining and cul- 
 ture inoculations upon slants were also made at the 
 bedside from aspirated matter obtained from 
 oedematous periglandular tissues or from gland 
 puncture, an aspirating syringe being used. The 
 drop or two of fluid which can be expelled from 
 the hollow needle is usually sufficient for smears 
 and tube inoculations. 
 
 Non-biologic Diagnosis. — I do not contend 
 that other diagnostic means than biologic ones 
 should not be used in plague. 
 
 On the contrary, it will inevitably happen at 
 times that resort must be had to methods of diag- 
 nosis which are purely clinical. When this is the 
 case, treatment, along lines to be detailed presently, 
 should be instituted upon the establishment of a 
 presumptive diagnosis. This presumptive diag- 
 nosis may be reached after due consideration of 
 physical signs and symptoms. A carefully taken 
 
170 PLAGUE 
 
 history of the onset and course of the disease will 
 be valuable but unfortunately such histories can 
 rarely be secured. It is far safer to mistakenly 
 pronounce a case " plague " and to institute ap- 
 propriate treatment, than it is to hesitate in the 
 absence of a perfect clinical picture and to permit 
 the golden moment for treatment to pass. 
 
 It must be remembered that septicsemic, bu- 
 bonic and pneumonic plague are all manifestations 
 of systemic infection with B. pestis; that they are 
 all expressions of the same disease; that they call 
 for the same treatment and that when the distinc- 
 tive signs of bubo or pneumonia appear the disease 
 is dangerously advanced. 
 
 It should also be reahzed that every case is, 
 almost from its onset, a septicsemic case, either 
 mildly or overwhelmingly so. Accordingly the 
 treatment should invariably be the treatment of 
 septicasmic plague. 
 
 The attitude of the diagnostician should be one 
 of suspicion and he should have the courage to 
 carry out antiplague treatment, practically upon 
 suspicion. In this way only can the mortality of 
 plague be greatl}'' reduced. It is true of plague, 
 just as it is true of cholera, that many of the fatal 
 
ITS DIAGNOSIS AND TREATMENT 171 
 
 cases develop and become hopeless before the dis- 
 ease is suspected or diagnosticated. It is also true 
 that many fatal cases of plague, in times of epi- 
 demic, completely escape recognition during life, 
 the diagnosis being made in the autopsy room. 
 
 Therefore, I lay great stress upon the necessity 
 for an attitude of suspicion on the part of prac- 
 titioners, wherever even a single case of plague 
 (human or rodent) is known to have occurred. 
 
 When it becomes necessary to establish a pre- 
 sumptive diagnosis, i.e.^ without resort to the micro- 
 scope, the following symptoms and physical signs 
 will be found to be most significant. 
 
 Symptomatology. — Acuteness of onset; ra- 
 pidity of fever development ; rapidity of the devel- 
 opment of mental dulness or cloudiness, impairment 
 of speech, delirium, stupor or restlessness; early 
 and extreme prostration (perhaps more pronounced 
 than in any other acute disease) ; extreme tender- 
 ness over involved gland masses, in the bubonic 
 type of plague; cough, with considerable frothy 
 sputum, soon becoming blood-discolored, in the 
 pneumonic type of plague; and early cardiac 
 asthenia in all clinical types of plague, septicsemic, 
 pneumonic and bubonic. 
 
172 PLAGUE 
 
 The following diseases may be confounded with 
 plague, if symptoms alone are considered: typhus 
 (evcanthematicus) , influenza pneumonia, broncho- 
 pneumonia, severe malaria, septicaemia, acute toxic 
 typhoid, venereal bubo, mumps and tonsillitis. 
 
 I call attention again to the fact that mild cases 
 of plague, septiceemic and bubonic, occur at times, 
 clinical pictures in such cases being incomplete. 
 
 The statement that the prognosis in all cases 
 of septicaemic plague is hopeless is not confirmed by 
 my experience. 
 
 It should also be remembered that primary 
 pneumonic plague and secondary pneumonia devel- 
 oping in the course of systemic plague are quite 
 diiFerent in their significance and mortality, pri- 
 mary pneumonic plague being well nigh invariably 
 fatal. 
 
 Pathologic Considerations. — Only the stu- 
 dent of plague pathology, who has seen a large 
 number of complete autopsies, can understand how 
 universal is the involvement of organs, glands and 
 tissues in systemic plague and how widespread is 
 the distribution of B. pestis throughout the body, 
 and he will best understand how treatment, to be 
 
ITS DIAGNOSIS AND TREATMENT 173 
 
 in the least effective, must be given in the very 
 earliest hours of the disease. 
 
 Plague is an exquisitely septic£emic disease and 
 this fact must never be lost sight of by the thera- 
 peutist, who must realize that from the earliest 
 moment of infection all plague is septicsemic plague. 
 
 Treatment, Conditions and Prognosis. — 
 Passing to the subject of treatment let us, first of 
 all, admit that even under the most favorable and 
 approved conditions of treatment the mortality is 
 extremely high. On account of the delay which 
 usually occurs in the recognition of plague, — a 
 delay which in the natural order of things is and 
 must be the rule rather than the exception, because 
 of the rapidity of onset of the disease and the fact 
 that it occurs much more frequently in the lower 
 social classes than elsewhere, — ^no brilliant results 
 are to be expected from any plan of treatment. 
 
 The matter of plague treatment is far from 
 being in the same satisfactory state as the matter 
 of preventive control. I do feel, however, that 
 biologic treatment from the earliest possible mo- 
 ment, with serum, is of the greatest promise, how- 
 ever discouraging the general prognosis may be 
 in plague. 
 
174 PLAGUE 
 
 Serum Treatment. — Recent writers agree 
 that there is no treatment with curative value ex- 
 cept that with antipest serum. To this behef I 
 subscribe assent, as I find it entirely in accord with 
 my experience and that of my colleagues in Manila 
 during 1912-1914. 
 
 Holding this view, I can see no reason for 
 repeating here the details of purely symptomatic 
 treatment. Symptomatic treatment has for its ob- 
 ject the securing of comfort and of relief from suf- 
 fering for the patient and is highly proper in its 
 place, remembering always that it is not curative 
 and that if employed alone it is worse than in- 
 adequate. 
 
 Symptomatic Treatment. — Opiates (mor- 
 phine by needle) for pain, delirium and excitement; 
 application of ice bags and cold or tepid sponge 
 bathing for high temperature ; stimulants for heart 
 weakness, are all indicated and are required in 
 nearly every case of plague. 
 
 As a rule surgery is not called for nor appro- 
 priate, except in cases which develop secondary sur- 
 gical conditions, which conditions we need not con- 
 sider at this time. 
 
 Statistical Studies in Mortality. — The sta- 
 
ITS DIAGNOSIS AND TREATMENT 175 
 
 tistical study of plague mortality from the point of 
 view of treatment is misleading and unsatisfactory 
 for reasons already given in our discussion of treat- 
 ment, viz.: failure to secure early recognition and 
 early serum treatment, and the greater incidence of 
 plague in the lower social classes. 
 
 Few statistical compilations divide the cases 
 studied into moribund and non-moribund, and in- 
 deed such division, being a matter of judgment, 
 largely involves the personal equation of the 
 observer. 
 
 The ease with which statistics may be moulded 
 to support theories, or to break them down, all 
 with perfect honesty of purpose, is proverbial. 
 
 To me, the spectacle of a single case of plague, 
 apparently ill unto death, recovering under the ad- 
 ministration of antiplague serum, is more impres- 
 sive than the contemplation of statistics ; and I have 
 seen more than one such case respond to serum 
 treatment and recover. 
 
 So far as it goes, however, the study of statistics 
 supports the view that treatment with antiplague 
 serum is effective. 
 
 I have not at hand the records of the last 
 
176 PLAGUE 
 
 20 or more cases, but of the fii'st 68 cases of plague 
 in the recent Manila epidemic, 32 were either found 
 dead or died upon the same day that they were 
 found. 
 
 If we exclude these cases from consideration 
 there remain 36 cases. All of these patients re- 
 ceived serum treatment and ten of them recovered. 
 
 It is at once apparent that this percentage of 
 recoveries (27 per cent, plus) is far more favorable 
 than the actual percentage of recovery in the series 
 in which cases found dead and moribund are con- 
 sidered, the recovery percentage here being a little 
 more than 14 per cent. It is also quite fair, it seems 
 to me, to make this separation of cases, or even a 
 more liberal one, if we are to consider the effects of 
 serum treatment statistically. 
 
 Dosage and Technique of Serum Adminis- 
 TEATiON. — The amount of antiplague serum to be 
 given will vary somewhat with the age and weight 
 of the patient and with the apparent severity of 
 the case. 
 
 In general terms it may be said that adults 
 should be given from 300 c.c. to 500 c.c. of serum 
 by injection, 100 c.c. being given every four hom-s. 
 
ITS^DIAGNOSIS AND TREATMENT 177 
 
 The injection may be either intramuscular or in- 
 travenous. 
 
 In view of the improvements in technic of in- 
 travenous administrations and its comparative 
 simphcity, and especially in view of the uncertain- 
 ties and delays of absorption from the tissues, the 
 intravenous route should be given the preference. 
 The serum may be delivered intravenously from a 
 large glass syi'inge, the introduction being very 
 slowly made, or through a gravity apparatus, as in 
 the administration of salvarsan. The serum should 
 not be diluted. 
 
 The use of antiplague serum for protective (im- 
 munizing) purposes is also recommended — espe- 
 cially when exposure to infection has occurred — in 
 the same way in which diphtheria antitoxin is used. 
 Its protective properties are conceded to be some- 
 what superior to those of plague vaccines as the 
 protection conferred is immediate, whereas plague 
 vaccines do not protect until sometime after their 
 administration. The dose is from 30 c.c. to 50 c.c. 
 
 Prophylactic Serum and Anaphylaxis. — 
 On one occasion in Manila in 1913, when some 
 30 persons were given prophylactic doses of serum, 
 intramuscularly, following a particularly danger- 
 
 12 
 
178 PLAGUE 
 
 ous exposure to fleas from rats dead from plague, 
 there occurred a number of cases of " serum sick- 
 ness" (anaphylaxis). These persons suffered 
 from severe urticarial, arthralgic and nervous 
 symptoms, lasting for several days and a few were 
 obliged to enter a hospital. In one case the symp- 
 toms did not entirely abate for a week. It has been 
 stated that newly-prepared sermn is particularly 
 apt to produce serum sickness when used for im- 
 munizing purposes. This form of protection is 
 brief (1 to 2 weeks) and is best suited for use where 
 there has been special exposure. 
 
 Plague Vaccines. — ^Haffkine originally pro- 
 posed prophylactic immunization, using killed broth 
 cultures of B, pestis ( carbolized to % per cent. ) , giv- 
 ing two injections at intervals of 10 days. Statis- 
 tically it seems to be shown that this prophylactic 
 immunization with dead bacteria reduces the in- 
 cidence and mortality one-fom'th or one-half (ap- 
 proximately). Experimentally, also, it appears 
 that antibodies (agglutinins) are produced by the 
 vaccine (and modifications thereof). Instead of 
 broth cultures, normal salt solution suspensions of 
 killed pest bacilli are usually used in vaccines at 
 present. 
 
ITS DIAGNOSIS AND TREATMENT 179 
 
 Castellani ^ has prepared a combined cholera 
 and plague vaccine for use in countries where both 
 diseases coincidentally prevail. It is a mixed 
 vaccine, so prepared that 1 c.c. of the emulsion con- 
 tains 1000 millions of plague bacilli and 2000 
 millions of cholera vibrios. The cultures are grown 
 on agar, killed by phenol and suspended in normal 
 salt solution. 
 
 He finds ( 1 ) that inoculation of the vaccine in 
 the lower animals induces a production of pro- 
 tective substances for the plague bacillus and the 
 cholera vibrio; (2) that the inoculation of human 
 beings is harmless (producing less reaction than 
 the Haffkine inoculation) ; (3) that a small amount 
 of agglutinins, both for plague and cholera, appear 
 in the blood of most inoculated persons (similar to 
 amounts produced by Haffkine's vaccine), a rough 
 index only of the amount of immunity produced. 
 
 ^ A, Castellani: Journal of Ceylon Branch of British 
 Medical Association, June, 1914. 
 
INDEX 
 
 Anaphylaxis, 177 
 Appearance of plague in Porto 
 Rico, 26 
 New Orleans, 26 
 Manila, 26 
 Appeal for public cooperation, 
 
 126, 127 
 Australia, plague in, 22 
 Alaska, plague in, 22 
 Africa, South, plague in, 22 
 Africa, Central, plague in, 22 
 Africa, East, plague in, 22 
 Africa, British East, plague in, 
 
 25 
 Africa, Portuguese East, plague 
 
 in, 26 
 Asian marmot, 28 
 Australia, rat fleas of, 32 
 Activity of fleas, 33 
 Attenuation of virulence of 
 cholera organism, 35 
 Bacillus pestis, 35 
 Adaptability of rat to tempera- 
 ture and environment, 61 
 Anti-plague campaign in Manila, 
 
 1912-1914, 57 
 Amoy, importation of plague 
 
 from, 59 
 Anti-rat measures in R. R. cars, 
 
 92 
 Activity of fleas, 98 
 Austrian Plague Commission, 133 
 Agglutination of plague bacilli, 
 
 134-135 
 
 Animals suspected of plague, ob- 
 servations on, 146-149 
 
 Abatement of plague in Hong 
 Kong in 1914, 160 
 
 Anti-plague w^ork, dangers of, 
 163, 164 
 
 Bacteriologic observations, 127 
 Bacillus pestis, in air, 38 
 in ants, 138 
 in bedbugs, 33, 138 
 conveyance by fleas, 28, 
 
 30, 31 
 cultivation of, 133, 138 
 cultural characteristics 
 
 of, 133, 138 
 in circulating blood, 133, 
 
 136 
 in cats, 150 
 efi'ect of temj)erature 
 
 upon, 34 
 in flies, 33, 138 
 in fleas, 138 
 in lice, 33, 138 
 eflfect of seasonal con- 
 ditions on, 34 
 in cockroaches, 33 
 in sputum, 133 
 stability of virulence of, 
 
 35,36 
 in skin, 132 
 Blue, Dr. Rupert, 31 
 Brazil, plague in, 22 
 Black Death of Europe, 20 
 British East Africa, plague in, 25 
 
 181 
 
182 
 
 INDEX 
 
 Bite of flea, 31 
 
 Brazil, rat fleas of, 32 
 
 Bedbug, conveyance of B. pestis 
 by, 33 
 
 Barber, Dr. M., 38 
 
 Bacterial \iruses for rat destruc- 
 tion, 43 
 
 Bacterial virus, Danysz, 53 
 
 Bacillus, Danysz, 53 
 
 use of, in Odessa, 53 
 use of, in Cape Town, 53 
 
 B. typhi murium, 53 
 
 Bacillus, mouse-typhoid, of Loef- 
 fler, 53 
 
 B. enteritidis, Gartner's, 54 
 
 Bacterial rat poisons, use of, in 
 Japan, 54 
 
 Beginning of Manila epidemic, 
 60 
 
 Binondo, Manila, plague in, 63 
 
 Bamboo timbers, closing ends of, 
 71 
 
 Basements, insanitary, 73 
 
 Birth-rate of rats, 73 
 
 Bionomics of fleas, 77 
 
 Batavia, Dutch India (Java), 77 
 
 Bureau of Science, Manila, 93 
 
 Barn rat, 99 
 
 Burrowing ability of rats, 103 
 
 Breaking up rat nests, Manila, 
 106 
 
 Bacteriologic examination of 
 plague patients, 128 
 
 Blood-sucking insects, transmis- 
 sion of plague by, 137 
 
 Bacillus pestis, insects found to 
 contain (Table III), 138, 139 
 
 Biologic diagnosis of plague, 167 
 procedure, diagnosis, 168 
 
 Cause of plague, 28 
 
 Conveyance of plague, 28 
 
 Control of plague, 40 
 
 Crowell, Dr. B. C, 14 
 
 China, plague in, 21, 22, 24 
 
 California, plague in, 22 
 
 Central Africa, plague in, 22 
 
 California ground squirrel, 28 
 
 Contact, plague through, 29 
 
 Contagious plague, 29 
 
 Contagion, India Plague Com- 
 mission on, 33 
 
 Cockroaches in plague convey- 
 ance, 29, 33 
 
 Cats, plague in, 29, 76, 149 
 
 Chronic plague in rats, 35 
 
 Chronic rat plague, India Plague 
 Commission on, 35 
 
 Currie, Dr. D. H., 31 
 
 Creel, Dr. R. H., U. S. P. H. 
 Service, 31, 101 
 
 CasteUani, Dr. Aldo (dedication), 
 179 
 
 Ceratophyllus fasciatus, 32 
 
 Cat fleas, 32 
 
 Ctenocephalus, 33 
 
 Citellus beecheyi, 38 
 
 Cholera epidemics, spontaneous 
 abatement of, 35 
 organism, attenuation of viru- 
 lence of, 35 
 
 California, a plague centre, 41 
 
 Cost of rat proofing, 49 
 
 Chemical poisoning of rats and 
 ground squirrels, 54 
 
 Community, summary of preven- 
 tion for, 56 
 
 Close of year 1912 in Manila, 67 
 
INDEX 
 
 183 
 
 Closing ends of bamboo timbers, 
 
 71 
 Cat plague case in Manila, 76, 149 
 
 fleas, 78 
 Correspondence of Philippine and 
 
 Japan conditions, 83 
 Comparative statistics in rat 
 
 catching methods, 89 
 Cresols, 94 
 Coloration of rats, 99 
 Conformation of skulls in rats, 
 
 101 
 Climbing ability of rats, 102 
 Collection and forwarding of rats 
 
 (Manila), 133, 123 
 Case of Mr. C. (Manila), 124, 
 
 125 
 Concealing plague cases, 94 
 Conclusions concerning blood 
 culture in plague diagnosis, 
 136 
 from observations of plague 
 outbreak among experi- 
 mental animals (Manila), 
 146 
 Cat, natural plague infection in, 
 
 149-154 
 Conditions, treatment and prog- 
 nosis, 173 
 Combined vaccines, 179 
 
 Diagnosis of plague, 165 
 Definition of plague, 28 
 Digestive tract, infection through, 
 
 29 
 Dog fleas, 32 
 Droplet infection, 38 
 Destruction of rats by diseases, 
 
 53 
 
 Danysz bacterial virus, 53 
 bacillus, 53 
 
 use of, in Odessa, 53 
 use of, in Cape Town, 53 
 
 Destruction of rats by domestic 
 animals, 54 
 
 Disinfection of ship cargoes, 56 
 
 Dead, proper disposal of, 56 
 
 Dispersion of fleas from rat 
 cadavers, Manila, 65 
 
 Death-rate of rats, 73 
 
 Dutch India, Batavia (Java), 77 
 
 Duration of life of fasting fleas, 
 79 
 
 Dead rats in bamboo house tim- 
 bers, 87 
 
 Disinfection, theatre, Manila, 93 
 
 Deception and concealment of 
 plague cases, 94 
 
 Differential points in rats, unre-^ 
 liability of, 101 
 
 Driving out rats with formalde- 
 hyde gas (Manila), 106 
 
 Dangers of anti-plague work, 163, 
 164 
 
 Diagnosis, rapid, of plague, im- 
 portance of, 166 
 biologic, of plague, 167 
 non-biologic, 169, 170 
 
 Dosage and technique of serum 
 administration, 176, 177 
 
 Extension of plague, 19, 22 
 Egypt, plague in, 20, 22, 25 
 East Africa, plague in, 22 
 Epidemics, effect of seasonal con- 
 ditions on, 34 
 wane of, 35 
 Epidemic pneumonic pla^e, 38 
 
184 
 
 INDEX 
 
 Economic imtportance of rat de- 
 struction, 42 
 Estimations of loss by U. S. Agri- 
 cultural Department, 42 
 Effect of superstitions and re- 
 ligious beliefs in India, 43 
 of rat poisoning and trap- 
 ping, 73 
 Epidemiologic facts concerning 
 
 plague in Java, 82 
 Examination of fatal cases of 
 plague (Table I), 130 
 of cases of plague who re- 
 covered (Table II), 131 
 Experimental animals, plague in, 
 139-145 
 
 Flea conveyance of B. pestis, 30 
 Flies, conveyance of B. pestis by, 
 
 33 
 Fowls, plague conveyance by, 29 
 Flea's stomach, capacity of, 31 
 bite and plague conveyance, 
 31 
 Flea prevalence, effect of seasonal 
 
 conditions on, 34 
 Fox, Dr. Carrol, 31, 70 
 Fleas, dog, 32 
 cat, 32 
 mice, 32 
 
 ground squirrel, 32 
 activity of, 33, 98 
 Fumigation of ships, 46 
 Flea carriers, objection to do- 
 mestic cats and dogs as, 65 
 Favorable conditions for spread 
 
 of plague in Manila, 61 
 First Manila cases in 1912, 62 
 
 Fleas and their habits, 77 
 bionomics of, 77 
 rat, of Philippines, 78 
 of Australia, 78 
 of Italy, 78 
 cat, 78 
 
 per rat, variations in num- 
 ber of (Java), 78 
 Flea larvae, effect of temperature 
 and humidity on, 79 
 imago, effect of temperature 
 and humidity on, 79 
 Fasting fleas, duration of life of, 
 
 79 
 Flea prevalence, prediction of 
 plague extension from, 80 
 natural enemies of, 97 
 activity of, 33, 98 
 Field rat, 99 
 Family Muridge, 99 
 Ferocity of Mus decumanus, 109 
 Feasibility of fighting plague suc- 
 cessfully, 162 
 of Manila policy of plague 
 control, 162 
 
 Great plague of London, 21 
 Great Britain, plague in, 22 
 Ground squirrel, California, 28 
 Great Britain, rat fleas of, 32 
 Ground squirrel, fleas of, 32 
 Gartner's B. enteritidis, 54 
 Geographic grouping of plague 
 
 cases in Manila, 63 
 Ground-floor sleeping quarters, 79 
 General cleaning campaign, 
 
 Manila, 88 
 Garbage cans, sanitary orders, 
 
 Manila, 93 
 
INDEX 
 
 185 
 
 Guinea-pigs as indicators of in- 
 fected liouses, 96 
 Genus Mus, 99 
 Gray rat, 99 
 Gunomys (Nesokia), 100 
 Gnawing ability of rats, 103 
 German Plague Commission, 149 
 
 History of plague, 19 
 Hawaii, plague in, 22 
 Hong Kong, plague in, 24, 58, 154 
 Heiser, Dr. V. C, 31, 58, 70, 75, 
 
 89 
 Hobdy, Dr. W. C, 31 
 House cats as rat catchers, 65 
 Half wild cats as rat catchers, 55 
 Human plague in Tondo district, 
 
 Manila, 68 
 Houses in Tondo, light material, 
 
 71 
 House disinfection by spraying, 
 
 94 
 Household rat destruction, plan 
 
 for. 111 
 
 Hong Kong, notes on plague in, 
 
 by Dr. Roberg, 153, 154, 
 
 155, 156, 157, 158, 159, 160 
 
 the work of the Sanitary 
 
 Board, 158 
 abatemfint of plague in 1914, 
 160 
 Haflfkine vaccine, 178, 179 
 
 Introduction, 11 
 India, plague in, 24 
 Indo-China, plague in, 24 
 Infection through digestive tract, 
 
 29 
 Ingestion, plague, 29 
 India, rat fleas of, 3f 
 
 Italy, rat fleas of, 32 
 India Plague Commission on con- 
 tagion, 33 
 on chronic rat 
 plague, 36 
 Immunity, plague, 36 
 India, effect of superstitions and 
 
 religious belief in, 43 
 Isolation of sick, 56 
 Importation of plague from 
 
 Amoy, 59 
 Iloilo, P. I., plague in, 70 
 Insanitary basements, 72 
 Interpretation of the rat catch 
 
 and plague incidence, 91 
 Infected houses, guinea-pigs as 
 
 indicators of, 96 
 India Plague Commission, 100 
 Insects found to contain Bacillus 
 
 pestis (Table III), 138, 139 
 Importance of rapid diagnosis of 
 
 plague, 166 
 
 Japanese anti-plague serum, 18 
 Japan, plague in, 22, 25 
 Java, plague in, 25 
 Japan, bacterial rat poisons, use 
 
 of, in, 54 
 Jackson, Dr. T. W., correspond- 
 ence, 75 
 Java, Batavia, Dutch India, 77 
 Xenopsylla cheopis in, 77 
 variations in number of fleas 
 
 per rat, 78 
 epidemiologic facts concern- 
 ing plague in, 82 
 Javan village house, 84 
 
 "bale bale," rats in, 86 
 Java, sawah rat of, 100 
 
186 
 
 INDEX 
 
 Jumping ability of rats, 102 
 Java, studies of rat cadavers in, 
 104 
 
 Kerr, Dr. J. W., 31 
 Korn, Dr. W., U. S. P. H. Ser- 
 vice, 87 
 Kerosene as an insecticide, 94 
 
 London, great plague of, 21 
 
 Lantz, Dr. D. E., 31 
 
 classification of rats, 99 
 
 Loemopsylla cheopis, 32 
 
 Louse, conveyance of B. pestis 
 by, 33 
 
 Loeffler, mouse-typhoid bacillus 
 of, 53 
 
 Laboratory-proven plague rats 
 and others in Manila, 61 
 
 Light material houses in Tondo, 
 71 
 Manila, 85 
 
 Letter of warning and appeal, 
 125, 126 
 
 Location of rat cadavers in re- 
 lation to human plague cases, 
 Manila, 162, 163 
 
 Mortality, 22, 23, 174, 175 
 Menace of plague, 28 
 Manila, plague in, 26 
 Manufacture of anti-plague 
 
 serum, 18 
 Middle Ages, plague in, 20 
 Mexico, plague in, 22 
 Mauritius, plague in, 22, 25 
 Mediterranean ports, plague in, 
 
 22 
 Marmot, Asian, 28 
 
 Mice, fleas of, 32 
 
 Manchuria, pneumonic plague in, 
 
 37 
 Methods of entry of rats into 
 
 ships and cars, 52 
 Mouse-typhoid bacillus of Loef- 
 fler, 53 
 Murium, B. typhi, 53 
 Manila, Anti-plague Campaign in 
 1912-1914 in, 57 
 epidemic, 1912-1914, 57 
 plague at quarantine in, 58 
 importation of plague from 
 Hong Kong in 1912, 58 
 Mariveles Quarantine Station, 59 
 Manila epidemic, beginning of, 60 
 Mortality and numbers of Manila 
 
 plague cases, 61 
 Manila cases in 1912, first, 62 
 geographic grouping o f 
 
 plague cases in, 63 
 R. R. station focus, 64 
 dispersion of fleas from rat 
 
 cadavers, 65 
 close of year 1912 in, 67 
 Malolos, P. I., plague in, 69 
 Manila, taking charge of plague 
 suppression measures in, 70 
 plague fighting organization 
 
 in, 71 
 rat plague in U. S. Army 
 Commissary warehouse, 76 
 habitations and plague, 83 
 light material house, 85 
 general cleaning campaign, 
 
 88 
 theatre, disinfection in, 93 
 Mus rattus, 99 
 
 alexandrinus, 99 
 
INDEX 
 
 187 
 
 Mus decumanus, 99 
 
 ferocity of, 103 
 Manila, breaking up of rat nests, 
 106 
 driving out rats by formalde- 
 hyde gas, 106 
 rat killing with dogs, 107 
 rat nests in trees, 110 
 snakes in rat traps, 111 
 rat swallowed by snake. 111 
 Multiple house infection (Ma- 
 nila), 112-117 
 Manila, collection and forwarding 
 
 of rats, 123, 123 
 Mr. C, case of Manila, 124, 125 
 Mamla, bacteriologic observation, 
 127 
 outbreak of plague among 
 experimental animals, 139- 
 145 
 conclusions from observation 
 of plague outbreak among 
 experimental animals, 146 
 San Lazaro Hospital, 13, 69, 
 
 161 
 location of rat cadavers in 
 relation to human plague 
 cases, 162, 163 
 Mortality, statistical studies in, 
 
 22, 174, 175, 176 
 McCoy, Dr. C. W., 31 
 
 New Orleans, plague in, 36 
 Natural enemies of the rat, 43 
 National aid, necessity of, 56 
 Numbers and mortality of Manila 
 
 plague cases, 61 
 Nest materials, 86 
 Natural enemies of the flea, 97 
 
 Norway rat, 99 
 Notes on rat runs, 105 
 nests, 105 
 food, 105 
 Natural plague infection in a 
 
 cat, 149-154 
 Notes on plague in Hong Kong 
 
 by Dr. Roberg, 153-160 
 Non-biologic diagnosis, 169, 170 
 
 Objection to domestic cats and 
 dogs as flea carriers, 55 
 
 Order Rodentia, 99 
 
 Outbreak of plague among ex- 
 perimental animals (Manila), 
 139-145 
 
 Observations of animals sus- 
 pected of plague, 146-149 
 
 Plague conveyance, 28 
 in 1910, 24 
 
 conveyance by suction of in- 
 sects, 33 
 
 Porto Rico, plague appears in, 
 26 
 
 Public cooperation in plague con- 
 trol, 126, 127 
 
 Practicability of plague control, 
 15 
 
 Philippines, plague in, 23 
 
 Peru, plague in, 22 
 
 Persia, plague in, 25 
 
 Portuguese East Africa, plague 
 in, 26 
 
 Public Health Service, U. S., 26, 
 37 
 
 Pulex irritans, 32 
 paUidus, 32 
 
 Plague pneumonia, secondary, 39 
 
188 
 
 INDEX 
 
 Pneumonic plague epidemic, 38 
 Prevention problem, summary of, 
 
 37 
 Pneumonic plague, 37 
 
 in Manchuria, 37 
 Plague inununity, 36 
 
 treatment and diagnosis of, 
 
 165 
 control, 4)0 
 prevention, 40 
 suppression, 40 
 campaign in San Francisco, 
 41 
 Poisons used for rat destruction, 
 
 43, 44 
 Poisonous gases, rat destruction 
 
 by, 45 
 Prevention for community, smn- 
 
 mary of, 56 
 Proper disposal of dead, 56 
 Philippine Journal of Science, 
 
 58, 70, 128 
 Plague at quarantine in Manila, 
 58 
 from Hong Kong, Manila, 
 > importation of, in ,1912, 
 
 58 
 from Amoy, importation of, 
 
 69 
 cases, numbers and mortality 
 
 of Manila, 61 
 rats, laboratory-proven, and 
 
 others in Manila, 61 
 in Quiapo, Manila, 63 
 in Binondo, Manila, 63 
 cases in Manila, geographic 
 
 grouping of, 63 
 in Malolos, P. I., 69 
 in Iloilo, P. I., 70 
 
 Plague suppressive measures, Ma- 
 nila, taking charge of, 70 
 fighting organization in Ma- 
 nila, 71 
 Population, removal of, in emer- 
 gency, 74 
 Plague, cat, case of, Manila, 29, 
 76, 150 
 rat, in U. S. Army Ck)mmis- 
 sary warehouse, Manila, 76 
 Prediction of plague extension 
 
 from flea prevalence, 80 
 Plag-ue prevalence, seasonal ex- 
 planation of, 81 
 in Java, epidemiologic facts 
 
 concerning, 83 
 Manila habitations and, 83 
 Tondo (Manila) habitations 
 
 and, 83 
 cases, deception and conceal- 
 ment of, 94 
 commission, India, 100 
 Postmortem changes, in rats 
 (Table), 105 
 in rats (illustration), 
 
 105 
 time of death of rats as 
 indicated by, 104 
 Plan for household rat destruc- 
 tion, 111 
 Plague patients, bacteriologic ex- 
 amination of, 128 
 examination of fatal cases of 
 (Table I), 130 
 of cases vi^ho recovered 
 from (Table II), 131 
 comlmission, Austrian, 133 
 bacilli from circulating 
 blood, recovering, 134 
 
INDEX 
 
 189 
 
 Plague bacilli, agglutination of, 
 134, 135 
 
 diagnosis, conclusions con- 
 cerning blood culture in, 
 136 
 
 by blood sucking insects, 
 transmission of, 137 
 
 among experimental animals, 
 outbreak of (Manila), 139- 
 145 
 
 outbreak among experimental 
 animals, conclusions from 
 observations of (Manila), 
 146 
 
 observations on animals sus- 
 pected of, 146-149 
 
 commission, German, 149 
 
 in Hong Kong, notes on, by 
 Dr. Roberg, 153-160 
 
 in Hong Kong in 1914, abate- 
 ment of, 160 
 
 feasibility of fighting suc- 
 cessfully, 163 
 
 control, feasibility of Manila 
 policy of, 163 
 
 cases (human), location of 
 rat cadavers in relation to 
 (Manila), 163, 163 
 
 importance of rapid diag- 
 nosis of, 166 
 
 biologic diagnosis of, 167 
 
 a septicsemic disease in all 
 cases, 170 
 
 symptomatology of, 171 
 Pathologic considerations, 173 
 Prognosis, treatment, conditions 
 and, 173 
 
 Plague, serum treatment of, 174 
 symptomatic treatment, 174 
 Prophylactic serum and anaphy- 
 laxis, 177 
 Plague vaccines, 178, 179 
 
 Quarantine, modified, 56 
 station, Mariveles, 59 
 Quiapo, Manila, plague in, 63 
 
 Rat fleas of Italy, 33 
 of Brazil, 33 
 of Great Britain, 33 
 of United States, 33 
 Rats, chronic plague in, 35 
 subacute plague in, 35 
 Requisites of the practical sani- 
 tarian, 13 
 Russia, plague in, 26 
 Rats, wild, plague in, 39 
 
 effect of seasonal conditions 
 on, 34 
 Rucker, Dr. W. C, 31 
 Rosenau, Dr. M, J., 31 
 Rat fleas, varieties of, 33 
 of India, 33 
 of Australia, 33 
 Rat population of the world, 41 
 destruction, economic impor- 
 tance of, 43 
 extermination methods, 43 
 natural enemies of, 43 
 destruction, bacterial viruses 
 for, 43 
 poisons used for, 43, 44 
 trapping, 44 
 traps, varieties, 45 
 destruction by poisonous 
 gases, 45 
 
190 
 
 INDEX 
 
 Rats, starving, 47 
 Rat proofing, 48 
 
 cost of, 49, 93 
 infestation of ships, 50 
 adaptability of, 51 
 Rats, methods of entry of, 52 
 Rat destruction by rat diseases, 
 
 53 
 Resistance of rat to diseases of 
 
 bacterial causation, 54 
 Rats and ground squirrels, chemi- 
 cal poisoning of, 54 
 Rat destruction by domestic ani- 
 mals, 54 
 catchers, house cats as, 55 
 half wild cats as, 55 
 terrier dogs as, 55 
 on farms, terrier dogs 
 as, 55 
 Rapid diagnosis, importance of, 
 
 56 
 Rat cadavers, dispersion of fleas 
 in Manila from, 65 
 plague in Tondo district, 
 
 Manila, 68 
 proofing and rat destruction, 
 
 inapplicable at times, 73 
 poisoning, trapping, effects 
 of, 73 
 Rats, birth-rate of, 73 
 death-rate of, 73 
 Removal of population in emer- 
 gency, 74 
 Rat plague in U. S. Army Comr 
 missary warehouse, Manila, 
 76 
 fleas of Philippines, 78 
 of Australia, 78 
 
 Rat fleas of Italy, 78 
 
 breeding as influenced by 
 
 climate, 81 
 in Javan " bale bale," 86 
 in thatched roofs, 86 
 dead, in bamboo house tim- 
 bers, 87 
 Rat catch, variations in, 88 
 Rat catching methods, compara- 
 tive statistics in, 89 
 Rat catch and plague incidence, 
 
 interpretation of, 91 
 Rats, zoologic classification of, 
 
 98 
 Rat, ship, 99 
 field, 99 
 Rats, coloration of, 99 
 Rat, Norway, 99 
 gray, 99 
 barn, 99 
 sewer, 99 
 Rats, unreliability of differential 
 points in, 101 
 conformation of skoHs in, 
 
 101 
 gnawing abihty of, 102 
 burrowing ability of, 102 
 climbing ability of, 102 
 jumping ability of, 102 
 swimming ability of, 102 
 Rat litters, size of, 102 
 Rats as wire walkers, 103 
 as rope walkers, 103 
 Rat cadavers in Java, studies of, 
 104 
 time of death as indicated by 
 postmortem changes of, 
 104 
 
INDEX 
 
 191 
 
 Rats, postmortem changes in 
 (Table), 105 
 (illustration), 105 
 Rat runs, notes on, 105 
 nests, notes on, 105 
 food, notes on, 105 
 nests (Manila), breaking up, 
 106 
 Rats driven out with formalde- 
 hyde gas (Manila), 106 
 Rat killing with dogs (Manila), 
 
 107 
 Rat's nests in trees (Manila), 110 
 Rat traps, snakes in (Manila), 
 111 
 swallowed by snake 
 (Manila), 111 
 Rats, collection and forwarding 
 
 of (Manila), 122, 123 
 Recovering plague bacilli from 
 
 circulating blood, 134 
 Roberg, Dr. David, 154 
 
 Stability of virulence of B. pestis, 
 
 36 
 Spread of plague in recent years, 
 
 23 
 Suppression of plague, 40 
 San Lazaro Hospital, Manila, 
 
 13, 69, 161 
 Schobl, Dr. Otto, 14, 29, 30, 76, 
 
 96, 127 
 Strong, Dr. R. P., 16, 36, 38, 59, 
 
 135 
 Sixth century, plague in, 20 
 South America, plague in, 22, 26 
 Siam, plague in, 25 
 Suez, plague in, 2"^ 
 South Africa, plague in, 22 
 
 Scotland, plague in, 22 
 
 Sumatra, plague in, 25 
 
 Straits Settlements, plague in, 25 
 
 Simpson, Dr. W. J. 
 
 Suctorial parasites in plague con- 
 veyance, 33 
 
 Seasonal conditions, effect on 
 epidemics of, 34 
 on rats of, 34 
 on Bacillus pestis of, 
 
 34 
 on flea prevalence of, 
 34 
 
 Subacute plague in rats, 35 
 
 Spontaneous abatement of 
 cholera, 35 
 
 Secondary plague pneumonia, 39 
 
 Summary of prevention prob- 
 lem, 37 
 
 San Francisco, plague campaign 
 in, 41 
 
 Ships, fumigation of, 46 
 
 Starving rats, 47 
 
 Ships, rat infestation of, 50 
 
 Summary of prevention for com- 
 munity, 6Q 
 
 Ship cargoes, disinfection of, 6Q 
 
 Sick, isolation of, 56 
 
 Steamer, Loongsang, 69 
 Taisang, 59 
 
 Spread of plague in Manila, 
 favorable conditions for, 61 
 
 Sleeping quarters, ground floor, 
 72 
 
 Swellengreble, Ph.D., N. H., 77 
 
 Seasonal explanations of plague 
 prevalence, SI 
 
 Sanitary orders, Manila (garbage 
 cans), 93 
 
192 
 
 INDEX 
 
 Ship rat, 99 
 
 Sewer rat, 99 
 
 Sawah rat of Java, 100 
 
 Swimming ability of rats, 102 
 
 Size of rat litters, 103 
 
 Simpson, surgeon, U. S. P. H. 
 
 Service, 103 
 Studies of rat cadavers in Java, 
 
 104 
 Snakes in rat traps (Manila), 111 
 Snake, rat swallowed b y 
 
 (Manila), 111 
 Specimen, sanitary orders, 116- 
 
 121 
 Sanitary Board (Hong Kong), 
 
 the work of, 158 
 Symptomatology of plague, 171 
 Serum treatment of plague, 174 
 SjTnptomatic treatment o f 
 
 plague, 174 
 Statistical studies in mortality, 
 
 174-176 
 Serum administration, dosage 
 
 and technique of, 176, 177 
 
 Types of plague, 30 
 
 Treatment of plague, 165 
 
 Turkey in Asia, plague in, 25 
 
 Tarbagan, 28 
 
 Teague, Dr. O., 38 
 
 Terrier dogs as rat catchers, 55 
 
 Terrier dogs as rat catchers on 
 farms, 55 
 
 Tondo district, Manila, rat 
 plague in, 68 
 human plague in, 68 
 
 Taking charge of plague suppres- 
 sive measures, Manila, 70 
 
 Tondo, light material houses in, 
 71 
 
 Tondo, Manila, habitations and 
 plague, 83 
 
 Theatre disinfection, Manila, 93 
 
 Time of death of rat as indicated 
 by postmortem changes, 104 
 
 Transmission of plague by blood- 
 sucking insects, 137 
 
 Trained bacteriologist, necessity 
 for, 167 
 
 Treatment, conditions, and prog- 
 nosis, 173 
 serum, of plague, 174 
 symptomatic, of plague, 174 
 
 Technique and dosage of serum 
 administration, 176, 177 
 
 United States Public Health Ser- 
 vice, 26 
 rat fleas of, 32 
 
 Varieties of rat fleas, 32 
 
 of rat traps, 45 
 Variations in number of fleas per 
 
 rat (Java), 78 
 Van Loghem, Dr. J. J., 82, 84 
 Variations in the rat catch, 88 
 Vaccines, plague, 178, 179 
 Vaccine, Haffkine, 178, 179 
 Vaccines, combined, 179 
 
 Widespread dissemination in re- 
 cent years, 23 
 West Indies, plague in, 29 
 Wane of epidemics, 15, 35 
 Work of Sanitary Board (Hong 
 Kong), 158 
 
 XenopsyUa cheopis in Java, 77 
 
 Zoologic classification of rats, 98 
 
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