  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 epidemiology the world over are correct, to eradicate plague we need only to control its carriers. To exterminate the rat (and perhaps the marmot and ground squirrel), to prevent the transportation 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 discouragement must often be expected. Extended in its application to the whole plague-infected world Yet we are encouraged to face the situation by a glance at what has been accomplished. The United States, perhaps, presents the highest examples of achievement in the cases of San Francisco 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. Behind this movement, however, were the powerful machinery of the Federal Government, money in generous amount and a considerably aroused public, resentful of the mismanagement of the 1903 epidemic, whereby, through pure fear of financial loss to commercial interests and by a disgraceful suppression of the truth, California was made, permanently 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 rodents in cities by the hundreds of thousands, upon Economic Importance of Rat Destruction.—It is certain that the economic importance of rat destruction upon grounds other than those purely sanitary must be impressed upon the public wherever a rat campaign is to be carried on. The absolute inutility of the rat, its enormous destructiveness to crops, to merchandise in warehouses and in transit, to poultry, eggs, fruits and vegetables, to buildings and furniture, and its incendiary habits causing annual fire losses of considerable 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 consumption of two ounces, the ration for a full-grown rat, this grain value varies from sixty cents per year, for wheat, to two dollars per year, for oatmeal, 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 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. Crude phosphorus is chiefly used in similar pastes. When mixed with glucose its inflammable properties are said to be lost. Its inflammability 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 combined with glucose and one per cent. of cyanide of potassium. Soaked wheat, 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 persons 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 constructed upon various principles. It is sometimes 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 Carbon bisulphide has been extensively used in California in the burrows of ground squirrels. Its fumes, being heavier than air, penetrate the burrows and promptly poison or asphyxiate all living animals and fleas. Absorbent material of some kind is saturated with the liquid and placed in the entrance 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. Starving Rats.—The subjects of the starvation of rats and rat-proof construction may be considered together. Just as the pig in the Philippine Islands and elsewhere in the Orient must give place as a scavenger of human excreta to modern and decent methods of waste disposal, so must the rat, a garbage scavenger the world over, give place to systematic garbage collection and removal, with temporary 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, restaurants, bakeries, wharves and warehouses must be 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 approved 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 districts 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 intimate association with man (an apparently feasible matter through the rat-proof construction of buildings), protection against human plague is in great measure accomplished. RAT PROOF STRUCTURE WITH SOLID CEMENT BASE, SOLID CONCRETE POSTS, AND UNBOARDED CEILING 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 admitted, however, that practical control of the disease 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 confined 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 To prevent the transportation of rats in ships, trains and merchandise is an undertaking of difficulty as well as of importance. In the case of vessels 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 better known, perhaps, than the fact that all ships harbor rats, but, except to the initiated, the extent to which some ships are infested is by no means understood. 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 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 themselves 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 lighter 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 refrigerating rooms where they grow heavy coats of fur for protection against the cold. 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 passage 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 numbers 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. Rat Destruction by the Spread of Rat Diseases.—The proposal to destroy rats by wholesale, by spreading epizoÖtic diseases among them, through feeding them bacterial virus, has received much attention in the last ten years. In 1900 Danysz isolated a bacillus from field mice suffering an epidemic disease communicable to rats, and great hopes were entertained that by means of this method decided 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 paratyphoid On account of the natural resistance of rats to diseases of bacterial causation (plague being the most notable exception to this rule), and the clinical 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 chemical poisons seems to be a preferable method, at least equally effective and without most of the disadvantages 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 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, particularly if the construction of buildings is such as to permit them to get beneath the floors. The employment of these animals will necessarily be confined to individuals for the freeing of individual premises from rats. A fact to be borne in mind is one already 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. Summary of Prevention for the Community.—Before passing to the consideration of other matters I would sum up the measures of preventive treatment for the community. There must be (1) Active warfare against rats and other plague-affected rodents and their fleas; (2) Modified 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) International notification between governments of the occurrence of plague within their respective territories; (6) Lastly,—but we might say first in importance,—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 authority (national if possible), whose officers must I can best emphasize the importance of the observance of the principles I have laid down by introducing 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 Preceding the appearance of the first Manila cases there occurred upon incoming ships a number of cases of plague during the Spring of 1912, detected at quarantine. Although there is no conclusive evidence which connects these imported cases, originating in Hong Kong, China, with the epidemic 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 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 members of the crew and of the passengers that arrived in vessels from foreign ports was taken with a view to detecting 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 examined and found free from sickness of a suspicious nature and from elevations of temperature. Seventy-three persons were detained to serve a quarantine detention of seven days. On the evening of April 30, a Chinese passenger, aged fifty-one years, was found to have a temperature 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 rÂles; 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 Beginning of the Manila Epidemic.—Proceeding 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 Of these 90 human cases, 76 were fatal and autopsies were performed in all instances. Fourteen 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 believed 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 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 subsequent 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, however, is not clear, and, on the other hand, it is not wholly inconceivable that the rat epidemic and human plague cases at the railway station in October may have been secondary to this June case. Such speculation is fruitless, however, so far as establishing facts is concerned. The second case of human plague occurred 13 days later, June 25, in a resident of a district somewhat 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: September, 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 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 follows: Calle San Fernando (804–814), November, 1912, 4 cases; Calle Teodoro Alonzo (518), November 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. 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 human 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 connection necessary to explain the epidemic. After the railway epidemic of human plague, Four cases under one roof on Calle San Fernando (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 elsewhere. The other cases during October, November and December were apparently sporadic and unrelated, either to the other human cases or to the few scattering cases of rat plague discovered from time to time. Without doubt, however, all were actually related to preceding cases of rat plague, i.e., to undiscovered 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 advanced degree of desiccation and mummification defeated the biologic determination of the cause of 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 localities 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 bacteriologic studies of captured rats, made at the Bureau of Science. Of nearly equal weight was the observation concerning 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. 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 between 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 dilapidation 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 between rat plague and human plague. This relationship is additionally emphasized by referring to the memoranda concerning certain overcrowded houses, in the midst of the rat plague district, CLEANING AND RAT PROOFING IN BASEMENT OF 1226 CALLE JUAN LUNA IN WHICH TWO CASES OF PLAGUE OCCURRED. RAT CADAVERS FOUND UNDER BROKEN FLOORS (MANILA PLAGUE CAMPAIGN) 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, respectively, were definitely traced to the same house in Manila, number 12 Calle Aguila, Tondo, both patients having lived in the basement of this house until within 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 tenement at this address. Both patients were detected, while still alive, in Malolos, where they were living 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 connection it is interesting to note that no other cases have been reported from outside of Manila, except the 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 occurred in the person of a Chinaman who was reported to have come from Bais, Oriental Negros, but later investigation 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 October, 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 Suppressive 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. 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 bamboo timbers with cement and with tin cans, in the manner shown in photographs herewith. In addition 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 Rat-proofing and Rat Destruction.—While it is frankly admitted that rats may not be completely exterminated by poisoning and trapping, the statement, so frequently repeated of late, that destructive 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 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 poisoning and trapping death-rate in any given locality, provided that the poisoning and trapping, with the destruction of nests, be intelligently and continuously carried out. Rat-proofing and rat destruction, then, should In emergency, the removal of people from intimate 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 bubonic plague, slept upon the ground floor of this house upon a bamboo bed. All these basement dwellers in this district The roving rats which wander over these ground surfaces 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 infrequently, 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 recommendation contained in your letter of March 22, that on account of the danger of the spread of plague in the district in which plague has appeared extensively, the basement 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. Upon November 27, a cat, known to have caught and eaten rats recently at the same place, was reported 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 disease. A guinea-pig, inoculated from a swab introduced into the cat's rectum, also died from plague (see report of Dr. SchÖbl). 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 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 government at Batavia, Dutch India, in 1913, some interesting facts, developed by study and experimentation, 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 confirmatory studies in the Philippines, we may state some of the conclusions of the Java workers with propriety, and we may also point out similarities in the construction of certain Filipino and Javanese habitations in their relation to rat harboring. Swellengrebel, in Java, noted the number of fleas per rat, dealing with Xenopsylla cheopis (the commonest rat flea in Java) almost exclusively. It would not be unreasonable, therefore, to expect to find at least some of his observations applicable to the Philippine Islands. Swellengrebel failed to find Ctenocephalus canis (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 different 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 indicate rat plague, Swellengrebel offers the reasonable 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 As to the influence of temperature and humidity on the hatching of larvÆ, he concludes from experimentation 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 larvÆ reach the adult stage; and also that a saturated humidity (in artificial cultures), causing condensation of water in the substratum, is very fatal to larvÆ. 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 (¾) 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 human 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 It appears, therefore, that the seasonal explanation of greater plague prevalence, rat or human, is susceptible of several interpretations and I feel sure that in countries like the Philippines seasonal variations in heat do not suffice to rid the rats of fleas during 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 reasonable to expect more human plague from closer relationship of rat and man,—provided that no special measures were carried out. Such, however, is not invariably the rule, if statistical studies are to be taken as evidence, and so we are reminded that generalizations for countries of different climates and seasons are not wholly reliable. Rat breeding, as well as flea breeding, is influenced by climate, but as the reproductive activity of the rat is most retarded by cold weather—an Their well-known adaptability to changing conditions, however, permits them to house themselves comfortably above ground when driven out of these burrows and holes. Javan Observations.—The following conclusions were reached by Dr. J.J. van Loghem in a report upon "Some Epidemiological Facts Concerning the Plague in Java" (published by Civil Medical Service in Netherlands India-Batavia, 1912):
Concerning the prevention of plague by improving 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 Favorable 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 Observations.—Having in mind the experiences of the plague investigators in Java during the recent epidemics there (1911–1912), we sought, from the Not until rat plague invaded the special district of Tondo, in Manila, in March, 1913, did the opportunity 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 construction 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 palisades and has no separate floor, the earth serving as the floor. 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 sometimes 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 enclosed in a manner similar to the principal room of the Java house and the basement room may fairly 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 photographs. 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 bedstead. 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 BAMBOO HOUSE SUPPORTS NOT SEALED WITH CEMENT. NOTE HOLES GNAWED IN BAMBOO ENDS. RATS FREQUENTLY MAKE NESTS IN THESE HOLLOW BAMBOO RAFTERS. 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. Korn, P.H. Service, and the writer (T.W.J.) investigated a good many of these bamboo house-timbers and we not only found such evidences of rats as food, rat fÆces 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 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 Upon rainy days and the days just mentioned the rat catch almost invariably falls off. 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.[3]—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 47,075 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 [3] Reprint from the Public Health Reports, Vol. 29, No. 6, February 6, 1914.
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 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 during the abatement of plague, and in consequence this explanation does not apply strictly. It is true, however, that whenever plague occurred in districts theretofore free from the disease, rat catching was pushed vigorously in the surrounding localities. Making due allowance for all the factors mentioned I am impressed with the probability, amounting 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 suspected or likely to contain rats, and the similar treatment 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 affairs. Rat catching in Manila was systematically performed and all rats captured were turned over to the Bureau of Science for examination for plague. When plague foci were discovered the localities Rat-proofing.—The theoretic desirability and superiority of "out building" the rat, over all other methods of rat suppression, is admitted. The apparent impracticability of actually rat-proofing Manila at the present time and our inability to starve the animals out, justify the other and less permanent measure, viz.: rat catching. However, I heartily favor and urge 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 cinematographs and theatres in the city were disinfected upon Attempts at deception and concealment of plague patients, upon the part of members of their families, 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 occurred. 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 evidence of uterine hemorrhage, except slight menstrual signs, was found. The destruction of infected fleas in plague houses is of course the primary object of the disinfection 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 mixture of cresols (2 per cent.) and kerosene (98 per cent.) over all surfaces of the house, floors, walls, underlying ground, furniture So also at Calle Cabildo, where the superstructure of the house was a veritable sieve, there was a series of communicating double walls. At the house on Calle T. Alonso a similar condition 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 between At 1364 Calle Sande, Tondo, where 5 cases originated, the infections were undoubtedly almost synchronous and no infection occurred after disinfection 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 strikingly the necessity for disinfecting houses where human or animal plague cases have occurred. Upon December 17, 1912, Dr. O. SchÖbl, 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 before 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 Other guinea-pigs placed in plague houses on Calle Cabildo and Calle San Fernando, after disinfection of the premises, failed to acquire plague. Natural Enemies of the Flea.—It was observed during the studies in Java that certain natural enemies of fleas exist and operate against their laboratory cultivation and their natural reproduction. 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 Activity of Fleas.—It was also observed during 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 course, there must be considered the possibility of his falling considerable distances. ZoÖlogic Classification of Rats.—The matter of accurately, systematically and scientifically cataloguing and classifying rats is one of great difficulty and is not to be undertaken by anyone but a trained naturalist. However, some of the notes we have at our disposal, gathered from many sources, Dr. Lantz gives the following brief classification in his section of the publication, "The Rat and Its Relation to Public Health." Order: Rodentia. Family: MuridÆ. Genus: Mus. Species are many, but only three or four are cosmopolitan. 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 throughout the world and these are named according to color and habitat. In addition to the names given in Lantz's classification, we constantly see reference to the black house rat, the brownish-gray rat (Mus Alexandrinus), 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 recognized 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. Members 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 M. rattus and M. decumanus are both present and numerous and both are subject to plague, as shown by the presence of the disease in specimens examined. In M. rattus the prominent borders which separate 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 To determine these differences the heads of the rats are cut off, the tissues desiccated by antiformin, or by boiling and stripping. From experiences in Porto Rico, Creel, of the U.S. Public Health Service, concludes that M. 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 expert 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 Mus rattus female. Mus decumanus is generally conceded to be larger and more ferocious than Mus 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 The photographs introduced were taken under my direction in Manila in 1912, 1913 and 1914. Some of them show the character of the house construction in Tondo District, Manila, where plague flourished in 1913. Others illustrate methods of rat-proofing bamboo timbers in houses of light material. 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, gathered Notes concerning cases of multiple house infection are also presented as being of possible interest. 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 appearance 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 conditions 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 likely to attack the cadaver early and to obscure the deductions by their destruction of the body. PROGRESSIVE POST-MORTEM CHANGES IN RAT CADAVERS. THE NUMBERS INDICATE THE NUMBER OF DAYS AFTER DEATH
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 collection of notes concerning rat runs, rat nests and their locations and other data collected by the various working parties under the direction of Sanitary Special attention has been given to the finding and destroying of rat nests, and in this connection please note that during the month of May, 1913, one party of workmen (20 men) under 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, 1913, two parties (40 men) killed 772 rats by hand out of a total of 3019. This work occurred in Tondo District in connection with extensive cleaning and moving operations. At 1279 C. Sandejas[4] 7 rats were found in a nest at the foot of a cluster of bamboo trees, between the trunks. Nest was made of leaves. [4] C. is abbreviation for Calle, the Spanish term for street. At 728 C. Velasquez, Tondo, 12 rats were driven from a burrow underneath a thick cement floor by formaldehyde gas delivered in the burrow through 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. 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 beneath 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 ground 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. 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 runs and were caught. At 631 Zacateros 2 rats were smoked out and killed. 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 unopened, 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. 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, Pesqueria. 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. 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 24 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 coÖperation requested. Plan to be tested for at least two months. Memorandum concerning 1364 Calle Sande: Within 72 hours (April 25-27) five fatal cases of plague, all in Filipinos, occurred 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). JosÉ 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. JosÉ 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 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 silversmith, with JosÉ Raymundo and was employed by Simplicio Enriques. Simplicio Enriques, aged twenty-seven, a silversmith, conducting his business at 1364 C. Sande and employing JosÉ Raymundo and Pablo Banzon, was taken sick about April 23. He moved to two different houses in the interval 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 Hospital, 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 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 ground 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 mummified and unfit for bacteriologic examination they were burned. The living rat was examined at the Bureau of Science but was found These facts account for the epidemic at 1364 Sande very completely. The premises at 1364 Calle Sande were quarantined 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 addresses 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. 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 occurrence 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 nipa 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 unsanitary in a multitude of ways. Bamboo construction, 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 condition On May 15, at the daily inspection of contacts in the house 1226 C. Juan Luna, Filomena SuÑga, 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 effect. [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. One rat, large, mummified and dry and therefore 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 ParÁs, will commence cleaning operations at C. Ostra, 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, additional 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 Inspector in charge. Sanitary Inspector, Bureau of Health: Please place the gang of workmen under your charge in the square bounded by Calles Velasquez, Moriones, 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 unsuitable 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. VIEW OF HOUSE AT 447 CALLE CONSERVADOR, TONDO, WHERE INFECTED RATS WERE FOUND (MANILA PLAGUE CAMPAIGN) 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. The laborers, 60 men, divided into 4 parties of 15 men each under Assistant Sanitary Inspectors JesÚs, De la Rosa, Laxamana and ParÁs, will continue the cleaning operations now under way on both sides of C. Juan Luna south of C. Moriones (plague localities in the same neighborhood), 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 instituted 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 thoroughly investigate these premises and the houses, stables and other buildings in the vicinity. Search for rats, living [Signed] T.W. Jackson, Medical Inspector in Charge of Plague Suppression. Method of Procedure in Collecting and Forwarding Rats Suspected of Plague Infection 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 mixture, the rats are immersed, with a minimum amount of handling, as soon as they are found (whether in traps or dead from poison). 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 wetting, 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 containers they are delivered to the laboratory by cart, once or twice daily. Mr. C., an editor, was taken ill with plague on the night of September 18, sought medical advice and entered St. Paul's Hospital September 19, and was transferred to San Lazaro Hospital, September 20, with an established clinical and bacteriologic diagnosis of bubonic plague. He survived till September 22. Upon September 21, in the course of disinfecting 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 opening 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 pulverized A second rat cadaver, found at the same time in the same building, during cleaning operations, was similarly treated with identical results. There could scarcely be a stronger chain of convincing evidence against the rat and the flea, nor a more complete and convincing explanation of Mr. C.'s death than that afforded by these established facts and official documents. So far as I know there is no more striking case on record in the modern history of plague. Letter of Warning and Appeal.—The following letter of warning and appeal for coÖperation 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 proclamation, To Whom It May Concern: You are hereby informed that the district bounded by Calles Rosario, Juan Luna, DasmariÑas and Plaza Calderon (and possibly the neighborhood bordering upon this congested district) is a dangerous one for all persons living 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. This means rat-proofing, and owners are earnestly urged to 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 insanitary 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 SchÖbl.—The following observations upon the bacteriologic aspect of the Manila epidemic which we are considering were made by Dr. Otto SchÖbl of the Biological Laboratory of the Bureau of Science, Manila, and pertain to the cases of the 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 examination 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. Bacteriological Examination of Plague Patients In order to secure as early diagnosis as possible, the following procedure of investigation was adopted:
Cultures obtained by this method were examined microscopically, and the growths on various culture media were studied. Gram stain, LÖffler's methylene blue, and hanging-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 necessary 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 cultures
[A] Months.
Note.—The bubo in Nos. 2, 5, and 24 never opened spontaneously. The pus was aspirated at the time of the second, eventually third, examination. Nos. 11 and 19 opened spontaneously. A fistula formed along the canal which was caused by the puncture, and healed up in several weeks. Hard inguinal buboes of secondary order persisted in patient 19 at the time of second examination. No plague bacilli were found either in the bubo of the first or second order. Patient 20 had a considerable amount of pus in the inguinal primary bubo, but it was not opened until after the last examination. Two of the patients, cases 8 and 12, had numerous plague bacilli in the sputum at the time when the expectoration 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 covered 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.[5] 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 corresponding axillary bubo). It is possible that these lesions were the original port of entry of infection. Numerous plague bacilli were found in the skin lesions of these cases, both microscopically and in culture. [5] Kolle und Wassermann: Handbuch der pathogenen Mikroorganismen. Gustav Fischer, Jena (1903), 2, 521. The plague patients tabulated in Table II recovered. They were all treated with antiplague serum. While cases 5, 11, 19, and 24 appeared clinically 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 repeated The general opinion in regard to the presence of Bacillus 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."[6] [6] Journ. Hyg., Cambridge (1906), 6, 558. 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 hours 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 cultures in 16 out of 23 fatal cases. Not a single positive blood culture was obtained from the patients who survived. 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 30 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 septicÆmic stage of bubonic plague: (1) "A severe septicÆmia may [7] Ibid. (1907), 7, 395. 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 presence 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 Commission, 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 septicÆmic stage of plague, as evidenced by repeated blood cultures in the three patients who recovered, one can hardly avoid the impression that there is a certain degree of septicÆmia in every case of plague. The possibility of detecting the bacillus in the circulating 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[8] and later confirmed by the German Plague Commission. Vagedes, Klein, and others[8] pointed out the defects of the reaction as a diagnostic [8] Referred to in Kolle und Wassermann: Handbuch der pathogenen Mikroorganismen (1903), 2, 524. Although the recent work of Strong[9] and of Strong and Teague[10] 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. [9] The Philippine Journal of Science, Sec. B. (1907), 2, 155. [10] Ibid. (1912), 7, 194–201. 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. [11] It is hoped that it will be possible to examine some of the survivors for agglutination from time to time. 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, agglutination 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 conclusions are drawn:
II. Observations on the Transmission of Plague By Blood-sucking Insects Judging from the data which have been collected from the literature[12] on the transmission of plague (Table III), Simond seems to have been the first to call attention to [12] Centralbl. f. Backt., 1 Abt. (1897), 22, 87, 437. Report of Indian Plague Commission (1898–99). Zeitschr. f. Hyg. u. Infectionskrankh. (1901), 36, 89. Kolle und Wassermann: Handbuch der pathogenen Mikroorganismen (1903), 2, 538. Zeitschr. f. Hyg. u. Infectionskrankh. (1905), 51, 268. Journ. Hyg., Cambridge (1907–10), plague numbers. Ibid. (1908), 8, 162, 260. During the recent outbreak of plague in Manila, several samples of bed-bugs from the beds of the plague patients and dog fleas from a plague-infected 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 The cage containing the dead rat was immersed in kreolin solution. At autopsy the cervical glands were found slightly swollen, somewhat reddened, but no hÆmorrhagic oedema of the surrounding tissue was noticeable. There was slight necrosis at the place of inoculation, showing superficial, purulent discharge. Clear effusion in both pleural cavities and one hemorrhage in the pleura were found. The lungs were hyperÆmic, 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 typical, 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 Loemopsylla cheopis Rothsch. The parasites were immersed in sterile salt solution for three hours. When removed in a dry test tube, they began to move about sluggishly. 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 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 centimetres 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, cervical 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 building 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. The gross lesions in these naturally infected guinea-pigs were somewhat unlike those found in guinea-pigs infected either by vaccination or by intraperitoneal or subcutaneous 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 involved. These are the findings usually met within 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 infiltrations partly covered with moist scab were found in the skin under the chin. Other animals showed changes A histological study of the tissues of these guinea-pigs known to be naturally infected by plague fleas showed the following changes: The Cervical Bubo.—The enlarged lymphatic gland was surrounded with a thickened capsule. Necrosis existed 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 present in the alveoli; otherwise normal. The Spleen.—The capsule was thin. There were subcapsular hemorrhages. The Malpighian bodies were somewhat enlarged, but of normal structure. Throughout the parenchyma irregular multiple necrotic foci were found, leaving but little of spleen tissue intact. Numerous polymorphonuclears which were present showed varying 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 degeneration, 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. It may be well to describe in detail the time of death from plague among these and the other animals in this outbreak, 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 3, 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 disinfected. 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 September 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. 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 bottom of the cage holds a drain opening 8 centimetres 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 construction of the wooden frame, allowed a continuous passageway 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 probability that the first partial disinfection drove the fleas away from the primary source of infection, and that they traveled as far as possible. The following conclusions can be drawn from these observations:
III. Observations on Animals Suspected of Plague Out of the several tens of thousands of rodents examined during the antirat campaign, we have found only 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 cervical 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 FriedlÄnder. Chronic plague was excluded in these cases since the animal inoculation failed to produce plague infection. More than half of the rats examined harbored parasites in their organs. Echinococcus taeniÆformis was found in the liver of practically every gray rat, while a small Ascaris and TÆnia diminuta were not uncommon in the intestines. Two rats were found to have sarcosporidiosis, 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 impression 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 slight oedema of the surrounding tissue. The subcutaneous injection extended over the neck and chest. The inguinal glands were small and pigmented. The lungs were collapsed, and showed hemorrhagic 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 yellowish foci thickly scattered throughout the tissue and visible through the capsule. The kidneys were hyperÆmic. The intestines 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, trabeculÆ 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 necrotic 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 infiltration. Polymorphonuclears were also found in the zone of cellular infiltration. There was a slight degree of Spleen.—The structure was well preserved, the capsule thin. The Malpighian bodies were normal as to the elements of which 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. Œdema 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 collapsed, and contained mucus. Kidneys.—The cortical part showed subdued structure; the epithelial cells had an indefinite outline and occasionally showed vacuolization. The medullar part was better preserved. There were miliary subcapsular hemorrhages. 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 Commission, [13] Über die Beulenpest in Bombay im Jahre 1897 (1897), II B, II C. One case of spontaneous plague infection of a cat was recorded by Thompson[14] in Sydney. [14] Report of an outbreak in Sydney, 1900. Referred to in Kolle and Wassermann (1903), 2, 510. W. Hunter,[15] in Hongkong made observations on cats suffering from plague infection. The author also undertook a few experiments, and arrived at the following conclusions:
[15] Lancet (1905), I, 1064. 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 The animal was a fairly well-nourished female.[16] The subcutaneous tissue, pericardium, mediastinum, and mesenterium contained considerable amounts of fat. [16] 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. The subcutaneous tissue of the neck showed oedema and small hemorrhages. The submaxillary tissues were swollen on both sides. When the fasciÆ and superficial muscles of the neck were removed, enlarged glands were found on both sides. These were closely attached to the submaxillary salivary glands. The surrounding tissue was oedematous, 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 axillÆ 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, sanguineous, slightly coagulated effusion was observed in both pleural cavities. The tissue of the lungs showed considerable oedema and hypostasis. The bronchi and pharynx showed no changes, the mucous membrane being pale and thin. The spleen was enlarged, of light red color, with follicles 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 venÆ stellatÆ 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 necrosis, 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 capillary mycotic emboli with subsequent hemorrhage were encountered. The large blood-vessels and bronchi were normal. Salivary Glands.—Those glands attached to the primary 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 Kidney.—The cells of the kidney showed various degrees of degeneration, ranging from parenchymatous to fatty infiltration. There were a few capillary hemorrhages and hyaline casts present. Suprarenals.—These showed slight degeneration. Spleen.—This organ showed congestion, a few hemorrhages, and bacterial emboli; otherwise normal. The bacteriological examination of the material from this cat gave the following results:
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 standpoint. To appreciate the important rÔle 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 remained apparently normal, may excrete plague bacilli which have retained their full virulence. Notes on Plague in Hong Kong by Dr. Roberg.—During the Hong Kong epidemic of plague which preceded and was coincident with that I have the following notes to present on the epidemic of bubonic plague in Hongkong. On April 5th when I arrived in Hongkong the epidemic 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. Illustrating the season for human plague, with its onset, 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 condition 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 September 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 greatness 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 respectively, 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 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 noteworthy 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 quarters, numbering about 4000 a day. The native houses have been built with double floors and walls which harbor the rats. Where the construction is of wood it is possible 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 The Work of the Sanitary Board 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 districts 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 Victoria and old Kowloon, one for the cemeteries and two for general duty. The measures employed by the Sanitary Board are summarized as follows:
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 observations made during the closing six months of the Manila epidemic. In February we found in one of the districts, in which we undertook systematic work in consequence 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 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 utmost thoroughness of treatment was insisted upon. The results fully justified our policy and demonstrated again how feasible it is to fight plague successfully 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 human 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 beneath 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 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 incriminated as to render these repetitions quite unnecessary, however interesting they may be to the plague worker. The danger of pursuing these investigations, | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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