Chapter III · ITS CONTROL AND SUPPRESSION

Plague Prevention.—At present the most promising and the most rationally based phase of plague control is that of prevention. The reason for this is plainly apparent. If the facts in the case are as stated and if the conclusions of the Plague Commissioners and students of 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 it becomes an undertaking seemingly impossible of accomplishment.

Yet we are encouraged to face the situation by a glance at what has been accomplished. The United States, perhaps, presents the highest 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 single farms by the thousand, and the wonderful procreative powers of the rat.

Economic Importance of Rat Destruction.—It is certain that the economic importance of rat 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 method of rat destruction to be depended upon to the exclusion of all others and it also shows that without governmental direction and supervision, backed by ample authority and the ability and willingness to expend considerable money, neither single nor combined methods will be successful. Moreover in the countries where special effort is most needed there is often distrust on the part of the natives, religious prejudice against the destruction of animal life and frequently open opposition to the authorities in their efforts to destroy rats. The same superstitions and religious beliefs which prevent the killing of venomous snakes in India, at the annual cost of thousands of human lives, operate against most measures of rat destruction proposed by the Government.

Extermination Methods.—The plans and weapons of warfare against rats include the use of poisons; traps; starvation; rat-proof construction of buildings, wharves, bakeries, stables, granaries, etc.; the introduction of diseases among the rat population by bacterial viruses and the conservation of the natural enemies of the rat, such as the cat, the dog, the ferret, the mongoose, and certain wild animals and birds of the woods and fields.

Among the most widely used and most effective poisons is arsenous acid boiled with rice, or mixed with cheese or cornmeal in the form of a paste, or placed upon sweets and fruits.

Crude phosphorus is chiefly used in similar pastes. When mixed with glucose its inflammable properties are said to be lost. Its 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 desirable to catch the rats alive and uninjured, and for this purpose barrel traps, wire cage traps and similar devices are placed in the rat highways. These highways are readily discovered in the cities. Considerable care must be taken to overcome the natural caution of the rat, and this includes judgment in the use of attractive bait, the concealing and smoking of traps after handling and perhaps the use of some scent, such as the oil of anise, of which rats seem to be fond. As a general rule bait should differ from the food naturally supplied by the locality. For example, about granaries and stables fresh animal food should be used for bait, while about slaughter houses, meat-markets, fish-markets and similar places, where animal offal is abundant, the rat should be tempted with vegetable bait.

Where the circumstances will permit, and this is apt to be so for ground-squirrel destruction, the burrows may be filled with some asphyxiating or poisonous gas. In this manner whole families of rodents, and their fleas as well, are destroyed.

The system is not often applicable in houses, but aboard ships it is found most effective, the holds of ships being flooded with sulphur dioxide, developed by burning sulphur in a special furnace provided with a pumping and piping system for delivering the gas at distant parts of the ship. In empty ships' holds and elsewhere the simple burning of sulphur in open vessels effects the same results, provided sufficient sulphur and a sufficient number of vessels be used and further provided that the generation and confining of gas be sufficiently prolonged. In San Francisco harbor, where for more than a year nine vessels were disinfected per day, this method was adopted as more effective, speedy and economical than any other system. It has the disadvantage, in the case of laden ships, of affording some danger of fire.

Carbon bisulphide has been extensively used in California in the burrows of ground squirrels. Its fumes, being heavier than air, penetrate the 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.

The method should never be employed by unskilled persons or those unacquainted with the dangers to human life from noxious or asphyxiating gases.

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 regulated by ordinances duly enforced. Much can be done with screens of heavy iron wire with a mesh of less than one inch.

When concrete and metal have displaced wood and plaster as construction materials; when plank sidewalks and refuse piles are no more and when the catch basins of sewers have been made rat-proof the subsistence problem for the rat will be greatly increased in difficulty, and starvation should then begin to lessen the rat population, at least in the cities.

Rat-proofing.—Municipal authorities should take up the matter of rat-proof construction for new buildings and the rat-proofing of old ones by 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

In Manila the disappearance and continued absence of human plague in previously infected localities goes hand in hand with the introduction of systematic rat-proofing in sections where cases of human plague occur.

These measures were first instituted in 1906 and plague disappeared from Manila in the same year and did not reappear until 1912.

From 1900 to 1905, $15,000 was paid in rat bounties and $325,000 was paid for salaries, wages and expenses in rat catching, with little appreciable effect upon the number of rats and without causing the plague to entirely disappear. It must be 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 prohibitive—at least in American governed cities. The Manila plan of plotting the city into "plague-infected" areas corresponding with the capture of plague-diseased rats and systematically working within geographic boundaries in which rat plague exists or is likely to spread, as determined by rat captures and examinations of the rats for signs of plague, has proved to be a good plan.

To prevent the transportation of rats in ships, trains and merchandise is an undertaking of 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 obliged to remain in her berth and see four large rats disport themselves about her room, and in another case, on the same ship, a rat jumped from the washstand into the berth of a sleeping woman, running across her exposed face and arm.

In travelling upon small dirty steamers in the Orient I have often slept on deck, quite as much to avoid the rats and vermin in the state-rooms as for better ventilation. In a certain ship in which I travelled some of the ship's officers amused 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.

They gain ingress to ships in three principal ways: (1) By coming overside upon gang-planks, wharf stringers, etc. (2) By passing along the lines by which the ship is made fast to the dock, through hawse holes, the rat being an expert rope walker. (3) By coming aboard in the cargo.

By the latter method rats are often brought aboard by whole families, their fleas included. Many styles of packages such as barrels, bales, crated goods, grain in sacks and matting in rolls present the rat with abundant opportunity to take 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.

The same principles which apply in the case of ships apply to cars and trains as well. Grain cars in particular should receive especial attention.

Rat Destruction by the Spread of Rat 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 bacillus and Gärtner's B. enteritidis correspond closely with the Danysz organism and can scarcely be separated culturally. In rodents they produce enteritis, sometimes hemorrhagic in character, and they are by no means to be regarded as harmless for man, as originally supposed. In Japan, in particular, serious and fatal cases of diarrhœal disease have followed the accidental eating by man of food treated by these bacterial poisons.

On account of the natural resistance of rats to diseases of bacterial causation (plague being the most notable exception to this rule), and the 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 the offending rodents, there is considerable difference of opinion, based upon varying experiences. I leave out of consideration all but the cat and dog.

It will be found that wherever cats and dogs are well housed (indoors) and well fed they are apt to be fat, lazy and inefficient. House cats of this class will catch mice but will often leave rats alone, but half-wild cats, obliged to forage for their own subsistence, are often excellent rat-catchers. Small, active dogs, particularly of the terrier breeds, will often keep houses practically free from rats and upon farms they are especially valuable, 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.

Furthermore, my personal observations have been such as to cause me to place small reliance in the value of the ordinary dogs and cats found about habitations wherein the construction is favorable to rat-harboring.

Summary of Prevention for the 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 be men of great moral courage and of unselfish purpose. Behind all of this must be generous financial support.

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 and five years for rodent plague, two verified human cases having been recorded in June, 1912.

Preceding the appearance of the first Manila cases there occurred upon incoming ships a number of cases of plague during the Spring of 1912, 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 bunk. The necropsy and subsequent biological findings reported by Dr. R. P. Strong of the Bureau of Science showed that death was due to pneumonic plague.

On April 7, 1912, the steamer Loongsang arrived in Manila from Hongkong, and the captain reported that a death had occurred the day previous in a Chinese member of the crew. Upon investigation of this case, the captain stated that the man was apparently in good health, but that while hauling on a rope he fell over in an apparent faint and was placed in a chair and in the course of a few hours expired. The necropsy and animal inoculations showed that he had died of plague and probably of the pneumonic variety.

Beginning April 7, 1912, the temperature of all 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 this day, the expectoration was blood-stained, but no suspicious organisms could be found in the smears nor could any physical signs of pneumonia be detected. Furthermore, there were no palpable glands. On the morning of the seventh day, the temperature and pulse dropped and the general condition was distinctly worse. The patient now admitted that he felt ill. Several hours later, he flinched when pressure was made in the right axilla. Lymphatic enlargement was now made out, and by the evening of the seventh day the bubo in the axilla had increased markedly in size, the swelling approximating 3 by 7 centimetres. Glands now became palpable in other portions of the body, particularly in the cervical region, and a few hours later there were inguinal and femoral buboes. The patient became rapidly worse, and died at 7 o'clock on the morning of the eighth day of his illness. At the necropsy, the glands of the right axilla and those of the right side of the neck were found enlarged; the other lymphatic glands were also enlarged, but to a lesser degree. There was consolidation of the lower lobe of the right lung, and the spleen was about twice its normal size. In brief, the necropsy findings of a typical case of septicæmic plague were present. Smears from the spleen and the right axillary gland showed immense numbers of bipolar-staining organisms. Cultures made from fresh pieces of tissues and later inoculated into animals gave positive results for plague.

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 from the time of the outbreak in 1912 until the last case in 1914 was 90. (This includes none of the imported cases from China which developed en route to Manila from Chinese ports.)

Of these 90 human cases, 76 were fatal and autopsies were performed in all instances. 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 and unnatural, geographic, human and domestic, which confront us at every turn of the path to correction, removal and reformation, our success in checking the spread of plague appears as a real achievement, especially when contrasted with the results of effort during the same period in a British city of similar size but a few days' sail from Manila, where the cases were numbered by thousands and where the infection still persists.

First Manila Cases.—The first case of plague (June 12, 1912) occurred in a resident of Tondo, 920 Calle Antonio Rivera, and in the light of 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 removed from the first case, but in the same general section of the city.

Then came a lull of more than a month, until August 4, during which time no case of plague occurred; or at least none was reported.

August brought forth five cases on the fourth, eighth, fifteenth, and twenty-first days of the month, in residents of the Quiapo and Binondo districts.

These cases were unrelated to the preceding ones so far as could be ascertained.

Another lull of a month, until September 24, now occurred without a reported case of human plague. During this time, however, the first cases of rat plague were discovered, one on August 30 and two on September 6, all of them in the Quiapo district.

From this time (September 24) on, however, human cases occurred at intervals of a few days until Christmas Day, 1912, the longest plague-free period being one week; the number of cases by calendar months being distributed as follows: 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 cases indicating a well localized infected centre. Upon this date there began the outbreak of plague among the employees of the Manila Railway Company, laborers at the freight station and yard of the company. This freight station and yard is located between Calle Azcarraga, Calle Dagupan and Calle Antonio Rivera. The outbreak totalled 17 human cases, all fatal, and extended into November. Indeed, the last case traced to this focus occurred on December 7, 1912.

During the present epidemic of plague in Manila this focus was the only one to which a larger number of cases than five could be traced, and in all the other instances where multiple cases were traced to an infected centre, the foci were all single buildings.

The locations giving rise to multiple infections and the number of cases of plague developing at each address, with months of incidence, are as 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.

Returning to the Manila Railway outbreak, it is necessary to state that a well-defined epidemic among rats preceded this outbreak, resulting in the death of a large number of rodents (undoubtedly from rat plague). This epidemic was not reported by the railroad company until the outbreak of human plague had begun. It was then too late to identify plague in the dead and mummified rats found under floors, platforms and elsewhere, but the fact that large numbers of rats had recently died here was established by the unanimous testimony of the employees at the freight station and the finding of rat cadavers.

As stated, the human outbreak here occurred upon October 21, and fifteen cases developed within 3 days.

This indicates an extensive desertion of fleas from plague rat cadavers and an attack upon 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, cases continued to occur through November and December, without apparent relation to each other, except in the following instances, which have already been mentioned:

Four cases under one roof on Calle San 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 death: 518 Calle Teodoro Alonzo; 973 Calle Azcarraga; 282 Estero de Binondo.

In other plague houses the recent finding of dead rats was alleged by the occupants, but rather too indefinitely to record positively.

A study of the maps and lists showing the 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. During this month no case of rat plague was reported.

In February, 3 human cases occurred and in March, 4 cases were recorded.

Early in March, 1913, cases of rat plague began to occur in the Tondo district in a section lying 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, where multiple human cases occurred. (See memoranda in re 1226 Calle Juan Luna and 1364 Calle Sande.)

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 small outbreak in Iloilo in the southern islands, where the antiplague work was successfully directed by Dr. Carroll Fox. Concerning this outbreak, Dr. Heiser, then Director of Health for the Philippines, writes as follows (Philippine Journal of Science, February, 1914):

Plague in Iloilo.—In Iloilo, a case suspicious of plague was reported on July 5, 1912, and this diagnosis was subsequently confirmed by the laboratory. It 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.

Plague Fighting Organization.—The plague fighting organization was composed of three American Sanitary Inspectors and from ten to fifteen native Assistant Sanitary Inspectors of the Bureau of Health, rat catchers and laborers of the Bureau and laborers of the City of Manila supplied by the Department of Sanitation and Transportation. The combined force varied in numerical strength from 100 to 150 men and was usually divided into three parties, distributed in various parts of the city according to the local indications and needs from time to time.

After the invasion of Tondo by rat plague we made special effort to rat-proof the light material houses of that section, in the course of our cleaning operations, by the closure of the open ends of 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 matter of depopulating the insanitary basements of the light material houses in squares where plague has occurred was given attention, with the result that hundreds of families were moved from these insanitary and dangerous ground-floor rooms to quarters well above ground and measurably removed from the rats, which roam over the ground from house to house, foraging for food under kitchens and in ground-floor storerooms, tiendas and eating places. The fish packing factories afford them abundant food and a number of cases of plague have occurred adjacent to these fish-drying establishments.

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 no choice permitted. Rat-proofing is highly desirable, permanent in its results, and in every respect the "method of election." On the other hand, it is entirely inapplicable at certain times and in certain localities where poverty, lack of interest of property owners, and ofttimes lack of interest and of money on the part of municipalities, absolutely preclude its immediate application. It is therefore unfortunate that the statement, that rat poisoning and trapping are ineffective, either in controlling plague or in reducing the numbers of rats, is circulated. It may be shown easily, by the daily records, that within a few weeks after extensive rat poisoning and trapping (with the breaking up of nests) is pursued in a given locality, the rat catch drops in the most decided manner.

Individual premises may be practically cleared of rats by continued intelligent rat catching and poisoning, and while the normal rat birth-rate may keep pace with the normal rat death-rate it will not keep pace with the normal death-rate plus the 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 not be contrasted as alternative procedures or policies. Both are valuable and each has a proper place. In communities non-infected with plague and unexposed to infection it will probably be found that rat-proofing, carried out in connection with the repairs of old buildings and the erection of new ones, will meet the requirements. On the other hand, in cities exposed to plague infection or already infected, rat destruction is bound to be necessary for years to come.

In emergency, the removal of people from 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 now infected with rat plague are in considerable danger.

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 26, 1912, five dead rats were reported from the U. S. Army Commissary Warehouses on the Pasig River near the Malecon. They were found dead by workmen there and were thrown into the river by the finders and thus, unfortunately, examination for plague was prevented.

Upon November 27, a cat, known to have caught and eaten rats recently at the same place, was 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 and in all buildings thereon, but no more cases of animal plague were discovered.

Fleas and Their Habits.—In "Observations Upon the Bionomics of Fleas Bearing Upon the Epidemiology of Plague in Eastern Java," by N. H. Swellengrebel, Ph.D., published by the 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. This flea, it will be remembered, is also the common rat flea of India, the Philippines, Australia, Italy, Brazil and tropical countries generally, being variously known as Lœmopsylla cheopis, Pulex pallidus, P. brasiliensis, P. philippinensis, and (in Italy) P. murinus.

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 increase in the number of fleas per rat, without a known normal cause, indicates increased rat mortality and probably rat plague.

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) perished within 10 days and the remainder lived from ten to twenty days, only one-tenth, however, surviving for 13 days, if moist conditions were maintained. High temperature was determined to be an unfavorable condition.

If from these findings one should attempt to predicate or predict the extension of plague in house rats—based on flea prevalence—and this with relation to climatic conditions, we should be led to the conclusion that the rainy season, with its greater humidity, would be quite the most favorable time of year for rat plague extension in Manila and, upon the contrary, that the hot dry season through its unfavorable influence upon flea breeding would be the least favorable season for rat plague in Manila.

The hot months of 1913 did not bear out this reasoning, however, for during these months rat plague was at its height.

That increased prevalence of 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 greatest prevalence of human plague in Manila during the late rainy season of 1912 (October), is the fact that rats are certainly driven above ground into houses and therefore into closer relationship with man by heavy rainfall and the consequent flooding of their subterranean homes.

It appears, therefore, that the seasonal 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 unknown condition in the Philippines—and as the climate of Manila is fairly equable so far as heat and cold are concerned, the only factor which needs to be considered is that of rainfall. As already mentioned, rainfall doubtless serves to drive rats above ground and so, to a certain extent, away from their nests in burrows and underground.

Their well-known 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):

In plague-infected villages, as distinguished from plague-free villages, there exists a considerable mortality among house rats.

Rats in plague houses and plague quarters have repeatedly died from plague. Fresh plague rats appear more often in the houses adjoining plague houses than in the houses themselves.

The house rat exists even in the immediate vicinity of man.

The ordinary parasite of the house rat is Xenopsylla [83]cheopis, which experimentally is known to choose man as a host when starving.

Fresh plague rats have repeatedly been found to harbor a great number of fleas.

Virulent plague bacilli have been demonstrated in the stomachs of such fleas.

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 time the Manila outbreak occurred, to verify some of the findings of the Java investigators, at least with special reference to the nesting of rats in close proximity to human beings and the consequent exposure of these persons to the infected fleas which desert the rats dying from plague in these nests.

Not until rat plague invaded the special district of Tondo, in Manila, in March, 1913, did the 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 outer frame is of strong bamboo poles and the inner frame is also constructed of bamboo. These bamboo timbers are perforated at various points to permit of framing with other pieces of bamboo and for the entrance of pegs, etc.

The roofs of these houses are often made of tiles, but at times the familiar thatched roof is seen. In both cases the supports or rafters are bamboo poles. The principal piece of furniture is the "bale bale," or bedstead, usually made of bamboo, except in the houses of the well-to-do. Small storerooms are often located in the houses, and stables are 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 be compared, structurally and in the matter of its floor, with the one-story Java house. In the Manila house, however, the floor of the upper room takes the place of the roof of the Java house and like it is supported by bamboo timbers.

Here, then, in our enclosed basement story, we have a practical replica of the one-storied Java house.

Here, also, the principal piece of furniture is often a bamboo bed, practically identical with the Java "bale bale," if we may judge from 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 nests by rats in Manila and Java seem to be identical also. Straw, dry leaves and pieces of cotton are mentioned in the Java reports. The same materials and additional ones will be found mentioned in our reports upon nests.

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 rat plague or human plague developed, were undertaken and this work was carried on without interruption for about two (2) years. City laborers to the number of 60 to 150 were used and the work was supervised by Sanitary Inspectors Brantigan and Searcy, of the Bureau of Health. During a part of the time a flying column of 50 men, under Sanitary Inspector Hunniecutt, was detached from the main party and employed at placing rat poison.

The total amount of accumulated dirt removed from houses and yards approximated 5250 tons (for 17 months ending November 1, 1913).

Without doubt this general cleaning campaign and the removal of this enormous accumulation of dirt and rubbish was of great value as an antiplague measure.

The rat catch will always be found to depend upon several factors, viz.: the number of persons employed; the number of traps and portions of poison placed; the location of the operations and the length of time a given locality is trapped, poisoned and cleaned. The variety of baits and poisons will also affect the results.

In addition to these factors certain others are found to operate in reducing the rat catch, as, for example, weather conditions and the occurrence of Sundays, holidays and the days just preceding and following holidays.

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 caught, which gives 7.47 for each 100 traps set. During this period 40,621 wire cage traps were set and 395 rats were caught, which gives 0.97 rat caught for each 100 wire cage traps set.

Kind of trap or poison Quarter ended June 30 Quarter ended Sept. 30

Number set Number of rats caught or poisoned Per cent. Number set Number of rats caught or poisoned Per cent.

Spring or snap traps 120,565 8,377 6.9 130,627 7,753 7.47

Wire cage traps 47,075 339 .72 40,621 395 .97

Poison bacon, rice, or coconuts 166,237 1,216 .731 177,309 216 .12

Quarter ended—

June 30 Sept. 30

Number of rats:

Caught by dogs 160 5

Killed with clubs and other weapons 2,889 3,818

Found dead from other causes 316 297

No accurate record was kept of the number of each kind of rat bait set. Only the total of all was recorded. Bacon or coconut with strychnine and rice with arsenic were used. For instance, for the quarter ended June 30, 1913, there were 166,237 poison baits set in new territory and the rats found poisoned average for each 100 baits 0.72. During the next quarter there were 177,309 baits set in territory that had been worked over, and only 216 rats, or 0.12 rat per 100 baits, were killed. From the foregoing it appears that the rat poison ranks lowest in efficiency but perhaps highest in economy. In view of the fact that the original cost of the cage trap is many times more than that of the spring trap, and the cost of maintenance is very high, it will be apparent that the spring trap is by far the more economical as well as more effective of the two.

Generally speaking, however, the number of rat catchers engaged and the location of their operations has the largest influence upon the total catch of rats. For the fiscal year July 1, 1912, to June 30, 1913, inclusive, the total catch was 55,101 rats (Manila only); to December 1, 1913, 79,676.

The most natural explanation of the general correspondence between the highest rat catch and the highest incidence of human plague would be upon grounds of greater activity in rat catching effort at times of greatest plague prevalence, but from the inauguration of general systematic rat catching there was no cessation of effort, even 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 almost to certainty, that the catch of more than 79,676 rats definitely affected and checked the spread of plague in Manila in 1913; and I am of the opinion that systematic and wholesale rat catching, carried out in the most economical manner possible, should be persisted in indefinitely, at least until plague disappears, wherever the disease occurs.

Efforts to prevent the spread of plague to the provinces of Luzon, by way of the railways, were successful and the present measures employed, freight inspection, the fumigation of packages 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.

MATERIALS MUST BE MOVED ABOUT IN THE SEARCH FOR RATS (MANILA PLAGUE CAMPAIGN)

When plague foci were discovered the localities were trapped and poisoned both circumferentially and centrally, with a view to preventing the diffusion of infected rats throughout the city.

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 repeated occasions by spraying with petroleum and cresols, with a view to destroying fleas and preventing plague infection.

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 and the spaces above ceilings, etc., using the mixture liberally and securing a general surface distribution. There is no doubt of the toxicity of this mixture to all fleas and bed-bugs which it reaches, and it is undoubtedly an effective measure in rendering an infected house safe. All of the instances of multiple house infections, where the cases recurred after disinfection, in Manila, have been in houses where, for one reason or another, the recommended structural rat-proofing has been postponed or where it has not been done. Thus, on Calle San Fernando the sequence of the four cases (their progress by days and in consecutive houses) is explained by the travel of rats through efficient rat runs present in the walls and ceilings, rather than by the passage of fleas through partition walls, from uncommunicating house to house.

A RAT INFESTED PLAGUE INTERIOR

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 two cases, the rooms and building were piled full of merchandise, defeating immediate disinfection, that is, efficient disinfection, until all the merchandise was moved and the rooms were emptied.

At 1364 Calle Sande, Tondo, where 5 cases originated, the infections were undoubtedly almost synchronous and no infection occurred after 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 and the guinea-pigs were left in the house for one day. Upon December 21 one of the guinea-pigs died from typical bubonic plague—anatomically and bacteriologically positive—other inoculated experimental animals also developing the disease.

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 Manila was frequently brought to my attention. We invariably included an attack upon ants in treatment of houses known to harbor, or suspected of harboring, plague rats. The combination of kerosene and cresols, elsewhere referred to, was found to be perfectly satisfactory in the destruction of ants; assuming, of course, that the necessary procedure of exposing the ants, by the moving of merchandise, boards or other protecting materials, was performed, so that contact, by spraying the insecticide mixture, was secured.

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, may be set before the reader. It is extremely difficult to find exact correspondence of statement in the various classifications offered by writers upon plague and rats.

Dr. Lantz gives the following brief classification in his section of the publication, "The Rat and Its Relation to Public Health."

Order: Rodentia.

Family: 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 aptitude of the rat for living in-door or out-door according to circumstances of food supply, weather, etc. The "sawah" rat of Dutch India, implicated in the prevalence of plague there, was formerly considered a variety of Mus decumanus, but is now described as a field variety of Mus rattus. So too, varieties of Mus decumanus are frequently named according to alleged geographic origin, habitat, color and habits, viz.: sewer rat, brown rat, Norway rat and migratory rat.

The inevitable confusion bound to arise from such loose classification is obvious.

Another genus, Gunomys (Nesokia), implicated in plague, is represented in India by two species and by at least one (an undetermined one) in Java, some confusion existing in the matter as yet. 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 view of the unreliability of the points of difference in rats usually given as identifying data, such as the number and location of the mammæ, the variations in color and the peculiarities of the footpads, the Javan observers depend upon the conformation of the skulls for the determination of genera, the skull of M. rattus being oval and arched, that of M. decumanus more closely approaching the square and rectangular conformation, and that of Gunomys being broader, higher and longer than either.

In M. 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. norvegicus (decumanus), while essentially a burrowing animal and not addicted to climbing or swimming, is nevertheless quite capable of doing either. He was found to burrow in the hardest earth to a depth of two and one-half feet and to pass through all kinds of wood, soft brick and lime mortar, probably by gnawing.

The black rat and Alexandrine rat (M. rattus) in Porto Rico, according to the same observer, do not burrow at all, but can climb and jump in 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 in the upper stories of buildings. Decumanus is known as a wharf rat, but is rarely trapped on ships on the Pacific Coast, according to the observations of Surgeon Simpson of the U. S. Public Health Service (Public Health Reports, April 11, 1913). According to the same observer, Mus rattus is the commonest ship-borne rat. He also states that the black rat and the roof rat (Alexandrinus), both varieties of M. rattus, differ chiefly in color. They live in upper floors, between ceilings, in walls and roofs and are remarkable climbers as well as being expert rope-walkers and wire-walkers. On account of their natural wariness and caution it is not always easy to induce them to enter or approach traps.

The photographs introduced were taken under my direction in Manila in 1912, 1913 and 1914. Some of them show the character of the house 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 and made in connection with our antiplague work in Manila, especially concerning the location and construction of rat nests found by our laborers; the materials used and the fabrication of the nests. Memoranda giving details of rat catching and rat-proofing are also presented and notes showing the location of dead rats found in relation to dead human bodies of plague victims.

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

Days after death Appearance

First to third day Distention of the abdomen, increasing.

Second to third day Loosening of hair by gentle pulling.

Third to fourth day Loosening of the epidermis by gentle pulling.

Third to fifth day Perforation of abdominal wall with collapse and disappearance of distention. This perforation may result from bursting of abdominal wall, or through anus, vulva or thorax.

Fourth to sixth day Moist shrinking of the body. Swarming of maggots. Spontaneous shedding of tufts of hair.

Fifth to eighth day Drying of body.

Eighth to twelfth day Complete dryness and rigidity.

Photograph (after Publications of the Civil Medical Service in Netherlands, India) shows the progressive postmortem changes in rat cadavers, the numbers indicating the number of days after death.

A Collection of Notes Concerning Rat Runs, Rat Nests, Their Location and Other Data.—Attention is invited to the following 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 Inspectors Brantigan, Renner and Kennard, of Manila.

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.

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 October 27, 1912, two of the rat terriers belonging to the Bureau of Health caught 192 rats in one storeroom at the Manila Railway Station, in 38 minutes. At various times they have killed from 10 to 25 rats at a single location, in connection with the cleaning and moving work done by the laborers. The dogs caught about 600 rats in all.

On March 11, 1913, 27 rats were caught by laborers at 202 Calle Concha. They were nesting in straw covers which had been removed from bottles.

On March 11, 1913, 13 rats were found 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.

On March 17, 1913, 14 rats were caught under a pile of hay and straw at 173 Velasquez. Nest was made from straw, chaff and hay.

The following articles of food were found in the above-mentioned nests: chicken bones, rice, coconut, fish and bread.

MEISIC DISTRICT

At 822 Sacristia 6 dead rats found in holes.

At 540 T. Alonso a family of 8 rats was smoked out and all were killed.

At 514 same street 6 rats were smoked out and killed.

At 538, interior, same street, 4 rats were smoked out and killed.

At 546 same street 4 rats were smoked out and killed.

At 715 San Bernardo dead rat found in a hole. Nest made of banana leaves and rags.

At 627, interior, Zacateros, 9 rats were smoked out and killed.

At 669 Benavides 6 rats were smoked out of four runs and were caught.

At 631 Zacateros 2 rats were smoked out and killed.

At 417, interior, Misericordia, 4 rats were secured in two holes under a tile floor. Many rats were caught at this number (interior) in traps.

At 221 Espelita 7 rats were found in a nest made of palm leaves and excelsior; location of run way and nest beneath tile floor.

At 124 Tetuan, in a nest of straw and lint, 5 rats were caught by hand, alive.

At 415 T. Alonso one live rat and 3 dead ones were dug out from beneath a tile floor.

SAMPOLOC DISTRICT

At 1001 Bilibid Viejo there were 5 rat runs, in a Chinese store. Eight rats were secured in a nest under the cement floor. Nest made of straw and paper.

At 928 San Sebastian there were 8 rat runs. In one of them there were caught 8 rats. The nest was made of straw.

At the same address, later, 3 rats were caught in another run and 8 young rats, with eyes still 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.

At the same address upon another day another rat run was found and one large rat and 16 small ones were taken from a nest made of rags, straw, and fibres.

PACO DISTRICT

At 1115 San Andres in a Chinese tienda (food store), a long rat run and a nest of rags, straw, and paper, and 30 small rats were found.

One nest in a bamboo tree 30 feet above ground was found. Rats had been observed going up the tree and one was caught at the foot of the tree in a trap.

SAMPOLOC DISTRICT

At 629 Tanduay 14 young rats and a nest of straw, paper and rags were found in a stable.

Same address, later, one rat run and nest of straw and rags with one large rat and 16 small ones were found.

TONDO DISTRICT

March 27, 1913, one rat was caught alive inside of a bamboo timber in house at 51, interior, 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.

A young python was caught in a lumber yard in the Santa Cruz District in June, 1913. In his stomach was found a half-grown rat. Another snake was caught in a rat trap at the same address about the same time.

Plan for Household Rat Destruction.—The following plan for household rat destruction was proposed by me to the Director of Health. It is considered worthy of trial if rat plague appears in new districts.

Proposal for periodic household rat poisoning in Manila.

Proposed that, upon a certain day of each week, rat poison be issued free to all applicants (householders) in Manila who agree to place same about their premises, permitting the poison to remain in place for 48 hours.

Instructions and poison placards to be issued with the poison. Issues to be made from Station Health Offices and records of issue to be kept.

Collections of dead rats to be made at the end of 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.

[112]MULTIPLE HOUSE INFECTION

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 April 26. At autopsy at San Lazaro morgue, the same day, bubonic plague was found to be present and the cause of her death.

Trinidad Galves, a young woman, aged sixteen, lived at 1364 Sande and was taken sick there on April 25. She was removed to San Lazaro Hospital and died there April 26, extensive plague lesions being found at autopsy.

Pablo Banzon, man, aged twenty-six, living at 646 C. Ylaya, was taken sick on Friday, April 25. He was removed to San Lazaro Hospital Saturday afternoon and died there Sunday evening, April 27. He was shown to have plague by bacteriologic examination made at the Bureau of Science. He worked at 1364 Sande as a 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 which cases of rat plague and human plague have recently been found. In our operations to put the house in a safe condition we found one dead rat, mummified, in the basement. Unfortunately, the workmen who swept it out did not note the exact location at which it was found. The house is in the midst of the district where rat plague has raged since early in March, 1913. The basement contained unauthorized and illegal sleeping rooms until a few days before this outbreak when they were removed in the course of our antiplague operations. The building is constructed of bamboo with a nipa thatch roof.

The front part of the basement was paved, but the pavement was undermined and broken. Being convinced that dead plague rats were present in the vicinity of this house and probably within it, I directed that the cement floor under the silversmith shop and the barber shop, located upon the 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 to be healthy. The cement floor was broken and permitted fleas from the dead rats to enter the basement room of the house which was occupied by the silversmith shop. The rats doubtless died from plague and the hungry fleas in due time attacked the nearest persons at hand, the unfortunate occupants of the silversmith shop and the two women who frequented the room also.

These facts account for the epidemic at 1364 Sande very completely.

The premises at 1364 Calle Sande were 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.

Memorandum reporting circumstance surrounding 2 cases of plague at 1226 C. Juan Luna (May 17, 1913):

Valeriano Lausin, aged fourteen, Filipino male, Carmelo maker by trade but out of work at time he was taken sick, recently removed to this house from 917 C. Jaboneros where he had been employed. The patient fixes the date at about a week previous to his sickness, but the proprietors of 917 Jaboneros are positive in their statement that he left the place where he lived and worked, at least two weeks before. This boy recovered.

The circumstances and especially the 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.

PLAGUE HOUSE, 1226 CALLE JUAN LUNA

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 of plague infection made it necessary to vacate and quarantine the building.

On May 15, at the daily inspection of contacts in the house 1226 C. Juan Luna, Filomena 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.

Upon careful investigation and search of the premises the following findings were disclosed:

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.

BAMBOO HOUSE SUPPORTS SEALED WITH CEMENT TO PREVENT ENTRANCE OF RATS (MANILA PLAGUE CAMPAIGN)

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, extending from the Bay to C. Sande and will clean towards C. Moriones. They will be provided with a disinfecting pump and will disinfect the ground surfaces wherever disturbed, outdoors and indoors. Cleaning is to be done in the most thorough manner possible, searching meanwhile for rat nests and rat harbors; re-piling wood, tiles, stones and merchandise; moving all movable goods out of doors in their search for rats and rat-holes or nests. All goods are to be piled above ground at an elevation of at least one foot. All bamboo beds and bamboo rafters and parts of the house (in the basements) made of bamboo or of double walls are to be thoroughly investigated for rats. All foodstuff attractive for rats is to be placed in covered boxes or galvanized iron cans, tin cans or barrels, with tight-fitting covers. Special attention is to be paid to straw, hay, shavings, grain, rat-holes, and food.

Two men will be detailed to cement up ends of bamboo and rat-holes, but will not do general repairing. They will carry materials for mixing cement as needed and will not be wasteful of materials.

If this force proves to be insufficient in numbers, 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, Concha and Manila Bay which is infected with rat plague. Treat the houses and properties there in the same manner in which other plague-infected districts have been treated, viz.: by policing the houses and yards, vacating all basements of light-material houses in which human habitations are illegally present; removing (with the consent of the occupants) all unauthorized basement sleeping places, beds, platforms, etc., and other illegal structures, closing up the open ends of bamboo rafters or timbers of the house with tin or cement.