Simplicio Enriques, aged twenty-seven, a_Plague Its Cause and the Manner of its Extension, Its Menace, Its Control and Suppression, Its Diagnosis and Treatment

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.

[Illustration: 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.

[Illustration: 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.

Where the occupants resist this action sanitary orders should

be issued in the usual manner and interference should be

stopped until the order is served and complied with. There

are a number of most insanitary and unsuitable shelters of

bamboo, tin, etc., used for houses by a number of families in

this square and it is desirable to tear down these huts if

permission can be secured. If permission is refused orders

should be issued on the usual form.

[Signed] T. W. JACKSON,

_In Charge of Plague Suppression_.

[Illustration: VIEW OF HOUSE AT 447 CALLE CONSERVADOR, TONDO, WHERE

INFECTED RATS WERE FOUND (MANILA PLAGUE CAMPAIGN)]

Specimen order issued by the Medical Inspector in charge of Plague

Suppression.

STATION "C," TONDO, May 21, 1913.

Redistribution of rat catchers and laborers engaged in

antiplague work. Effective May 2, 1913.

Sanitary Inspector Kennard and 20 rat catchers will move into

Tondo District and trap and poison rats in the district

bounded on the west by Manila Bay and on the east by Estero

Reina. The work will be begun at the extreme north water

boundary of this district and will proceed toward the south.

Sanitary Inspector Brantigan with a similar number of rat

catchers (20) will work within the same east and west

boundaries and will begin trapping and poisoning at Calle

Moriones, proceeding north. The poisoning and trapping is to

be done in the most thorough manner possible, as this is a

dangerously infected district and rat-plague must be

controlled and terminated here.

The laborers, 60 men, divided into 4 parties of 15 men each

under Assistant Sanitary Inspectors Jesús, De la Rosa,

Laxamana and Parás, will continue the cleaning operations now

under way on both sides of C. Juan Luna south of C. Moriones

(plague localities in the same neighborhood), and thoroughly

disinfect.

One party of 15 men will work in the vicinity of C. Perla,

vacate basements as habitations, search for dead rats in

yards, houses, bamboos, under broken concrete, etc., and will

close up openings in structural bamboo by means of tin and

cement. Emphasis is placed upon the necessity for permanently

vacating basements and men will be sent back over the ground

daily to see that the persons moved out do not return.

Reports are desired so that prosecutions for violations of

the law may be instituted if necessary.

[Signed] T. W. JACKSON,

_Medical Inspector in Charge of Plague Suppression_.

Specimen order issued to Assistants.

May 4, 1913. STATION "C," BUREAU OF HEALTH:

Please place work parties in (interior) 1627-1629 Sande and

525 C. Azcarraga, to clean, disinfect and thoroughly

investigate these premises and the houses, stables and other

buildings in the vicinity. Search for rats, living and dead,

rat nests and rats in bamboos and wood piles, stone piles,

stables, under planks and elsewhere. Cement the openings in

bamboos in houses or close with tin. Make notes on needed

structural work. Do the work as thoroughly as possible.

[Signed] T. W. JACKSON,

_Medical Inspector in Charge of Plague Suppression_.

METHOD OF PROCEDURE IN COLLECTING AND FORWARDING RATS SUSPECTED OF

PLAGUE INFECTION TO THE LABORATORY IN MANILA, P. I.--Rat

catching,--trapping and poisoning,--is conducted in accordance with

instructions contained in the Sanitary Inspector's Handbook (pp. 36,

37, 38) issued by the Bureau of Health.

Rats are collected in Manila and forwarded to the Bureau of Science for

autopsy and for biologic examination for the presence of plague bacilli

in the following manner:

The various groups of rat catchers are provided with receptacles (iron

pails) and a supply of a mixture of kerosene, cresol and water

(kerosene 10 parts, cresol 2 parts; water 88 parts).

In these vessels, filled with the pulicidal mixture, the rats are

immersed, with a minimum amount of handling, as soon as they are found

(whether in traps or dead from poison).

If captured alive they are killed and then promptly immersed. The

mixture must be well shaken or stirred when used, as it separates upon

standing. The immersion is, of course, for the purpose of destroying

any fleas which may be present upon the captured rat.

A paper tag showing the date and the exact location of the place of

capture, with the name or group number of the rat catcher, is next

affixed to a foot or to the tail of the rat and firmly tied upon the

same, where it remains until the rat cadaver is finally disposed of.

This tag is a card of strong Manila paper and the record upon it is

made with an ordinary lead-pencil, as both ink and indelible pencil

marks are apt to become illegible from wetting, whereas lead-pencil

marks are little affected thereby.

If desired, the disinfected tag in any given case of rat plague may be

returned to the Bureau of Health, for identification, where an accurate

record of every rat captured is kept.

After dipping and tagging, the rats are taken to a central point, again

dipped, and placed in large, tightly-covered, galvanized iron cans, in

which containers they are delivered to the laboratory by cart, once or

twice daily.

THE CASE OF MR. C.--The following are the facts concerning the case of

Mr. W. C., a prominent American resident of Manila who suffered and

died from plague in 1914.

Mr. C., an editor, was taken ill with plague on the night of September

18, sought medical advice and entered St. Paul's Hospital September 19,

and was transferred to San Lazaro Hospital, September 20, with an

established clinical and bacteriologic diagnosis of bubonic plague. He

survived till September 22.

Upon September 21, in the course of disinfecting the business office of

Mr. C., located in a district which had furnished a number of cases of

both rat and human plague, a dead rat, mummified, was found in the

right hand drawer of his desk and fleas were seen to hop from the

drawer upon opening it.

A flea killed by the disinfecting mixture at this desk was identified

at the Bureau of Science as a rat flea (_Xenopsylla cheopis_).

The rat cadaver was sent to the Bureau of Science and the following

facts were reported from there some days later:

The mummified rat and skeleton were pulverized in a sterile mortar and

an emulsion was made and injected into guinea-pigs. The animals died

from plague in a few days and plague bacilli were recovered from the

tissues, as well as from the rat cadaver, by culture.

A second rat cadaver, found at the same time in the same building,

during cleaning operations, was similarly treated with identical

results.

There could scarcely be a stronger chain of convincing evidence against

the rat and the flea, nor a more complete and convincing explanation of

Mr. C.'s death than that afforded by these established facts and

official documents. So far as I know there is no more striking case on

record in the modern history of plague.

LETTER OF WARNING AND APPEAL.--The following letter of warning and

appeal for coöperation was suggested and framed by me February 10,

1914, at the time that extensive rat plague was discovered in the heart

of the business district of Manila. I presented it to the Director of

Health with a strong recommendation for approval and publication and

after consideration he approved and authorized publication upon

February 10. No change was made in the wording of the proclamation,

but it was issued over the signature of the Director of Health to give

added force and authority to the appeal. The results were, as I had

hoped they might be, highly beneficial. The taking of the public into

the confidence of the health authorities brought about a coöperation,

without which our efforts in this difficult situation would have been

sadly handicapped. It is my belief that this method should often be

used by health authorities, particularly where an intelligent community

is threatened.

TO WHOM IT MAY CONCERN:

You are hereby informed that the district bounded by Calles

Rosario, Juan Luna, Dasmariñas and Plaza Calderon (and

possibly the neighborhood bordering upon this congested

district) is a dangerous one for all persons living or

conducting business therein, on account of the presence there

of extensive rat plague. Six human cases (with five deaths)

have recently developed there and many dead rats have been

found. All human cases have been directly traced to rats dead

from plague.

The Bureau of Health is now doing everything within its power

to make this district safe, but the attention of all

citizens, property owners and tenants is called to the fact

that they are required by law to keep their premises free

from rats and to abolish all structural conditions of the

buildings which favor the harboring of rats. This means

rat-proofing, and owners are earnestly urged to perform this

necessary work now, under the direction of the Bureau of

Health.

As a temporary expedient and safeguard all interiors, walls,

floors and ceilings should be sprayed with kerosene daily, or

at intervals of two days, to kill the fleas which carry

plague from rats to human beings. All dark insanitary places

used for living rooms should be vacated at once; all

merchandise should be piled upon trusses at least a foot

above the floor; all straw, shavings and other material

attractive to rats for nesting, should be removed and burned

and all food materials upon which rats may feed and live

should be placed in covered boxes, bins or cans.

All rat-holes should be permanently closed and all broken

cement or masonry should be repaired.

Observance of these instructions may save the lives of

yourselves, your families and your tenants. It is your duty

to do your part in this matter, a part which neither the

Bureau of Health nor the Government can do for you.

Through very great effort the Bureau of Health has controlled

plague in Manila and the Philippine Islands during the last

two years.

Residents must now do their part, and owners of property must

permanently make their buildings safe for tenants, both for

business and residential purposes.

BACTERIOLOGIC OBSERVATIONS MADE BY DR. OTTO SCHÖBL.--The following

observations upon the bacteriologic aspect of the Manila epidemic which

we are considering were made by Dr. Otto Schöbl of the Biological

Laboratory of the Bureau of Science, Manila, and pertain to the cases

of the first year of the epidemic. They were printed in the December

number of the _Philippine Journal of Science_ in 1913, but as they

belong so definitely to the epidemic I am describing and as Dr. Schöbl

has expressed his willingness for me to quote them in full, I gladly

accept his permission. Dr. Schöbl advanced the possibilities of

blood-culture diagnosis to such a point of reliability that it became

practically possible for us to expect positive culture in nearly every

case of true plague and the whole matter of bacteriologic diagnosis was

perfected to a high degree of efficiency under his administration of

the laboratory work.

He relates his observations as follows:

During the recent outbreak of plague in Manila, I had the

opportunity to make certain observations which are of

interest. These observations were made in the examination of:

(1) Specimens taken from patients and from dead bodies at

autopsies, (2) samples of blood-sucking insects collected in

houses where plague patients had lived, (3) rodents caught by

trap or poisoned in the parts of the city where plague cases

occurred from time to time, and (4) domestic animals suspected

of plague infection.

I. BACTERIOLOGICAL EXAMINATION OF PLAGUE PATIENTS

In order to secure as early diagnosis as possible, the

following procedure of investigation was adopted:

1. The bubo was aspirated by means of a sterile hypodermic

syringe. The material thus obtained was placed in the water

of condensation of an agar-slant culture tube.

2. At least 7 centimetres of blood were withdrawn from the

_cubital_ vein by means of another sterile syringe, and 5

centimetres of it were placed in an Erlenmeyer's flask,

containing 200 centimetres of neutral meat broth. The rest of

the blood was emptied into a sterile tube, and used for

agglutination tests.

Cultures obtained by this method were examined

microscopically, and the growths on various culture media

were studied. Gram stain, Löffler's methylene blue, and

hanging-drop method were used. Polar-staining and chain

formation in liquid media and the characteristic type of

colony on the surface of agar were looked for. Animal

inoculation was performed in every case, and the culture

isolated from each case was identified by agglutination test,

rabbit's immune serum being used.

The results of the bacteriological examination of a series of

24 patients are tabulated in the two following tables. Table

I includes the fatal cases and Table II those cases which

recovered.

The diagnosis of plague could be safely made from the

microscopical examination of the liquid aspirated from the

bubo in the majority of the cases. However, in certain

instances the amount of the aspirated fluid being small and

the bacilli very few, it was impossible to diagnose the case,

especially when the cultures from the bubo were negative.

Repeated examination of the patient was necessary under those

conditions, but it happened in cases 22 and 23 that the

patients died of plague before a second examination could be

made. The smears and cultures from case 22 remained sterile,

while the smears and cultures made from the swelling on the

neck of patient 23 revealed the presence of pneumococci. Both

patients died of plague, as was ascertained by examination of

the organs after death.

TABLE I.--EXAMINATION OF FATAL CASES OF PLAGUE

========================================================================

|Date of Examination 1912

| +--------------------------

| |Duration of illness _Days_

| | +----------------------

| | |Hours before death

| | | +----------------

| | | | Bubo

| | | |Smear

| | | | Culture

| | | | Animal

| | | | inoculation

| | | | +----------

| | | Age | | | | | Aggluti-

--------------+--------+----+-------+--------+---+-----+-----+----------

1. Sing Nu |Chinese |Male| (?) |July 11| 5 | 48 |+ + +|0 0

| | | | | | | |

Raymundo |Filipino|Male| 15 |Sept. 29| 3 | ... |+ + +|0 0

| | | | | | | |

Almalas |Filipino|Male| 39 |Oct. 10| 4 | 22 |+ + +|+ -

| | | | | | | |

Guzman |Filipino|Male| 34 |Oct. 22| 2 | ... |+ + +|0 0

| | | | | | | |

Sarmiento |Filipino|Male| 37 |Oct. 22| 3 | ... |+ + +|0 0

| | | | | | | |

Gonzales |Filipino|Male| 41 |Oct. 22| 3 | 23½ |0 0 0|+ -

| | | | | | | |

Buencamino|Filipino|Male| 31 |Oct. 22| 3 | 10 |+ + +|+ -

| | | | | | | |

Nicomedes |Filipino|Male| 30 |Oct. 22| 2 | 5¾ |+ + +|+ -

| | | | | | | |

Gulano |Filipino|Male| 34 |{Oct. 22| 2 |106 |0 0 0|+ -

| | | |{Oct. 24| 4 | 82 |0 0 0|0 0

| | | | | | | |

Dimalanta |Filipino|Male| 35 |Oct. 23| 3 | 25½ |+ + +|+ -

| | | | | | | |

Obiso |Filipino|Male| 5 |Oct. 23| 1 | 53 |+ + +|+ -

| | | | | | | |

Barceta |Filipino|Male| 23 |Oct. 24| 3 | 37 |+ + +|+ -

| | | | | | | |

16. Yu Tum |Chinese |Male| 14 |Oct. 24| 2 | ... |+ + +|0 0

| | | | | | | |

Monterey |Filipino|Male| 29 |Nov. 1| 1 | 27 |+ + +|+ -

| | | | | | | |

Pabraw |Filipino|Male| 27 |Nov. 23| 4 | 15 |0 0 0|+ -

| | | | | | | |

Sobremonte|Filipino|Male| 20 |Dec. 7| 6 | 1 |+ + +|+ -

| | | | | | | |

Marcelo |Filipino|Male| 8 |Aug. 20 |(?)| ... |- - -|0 0

| | | | | | | |

Gita |Filipino|Male| [A]17 |Nov. 24 | 3 | ... |- - -|0 0

--------------+--------+----+-------+--------+---+-----+-----+----------

========================================================================

|Date of Examination 1912

| +--------------------------

| |Duration of illness _Days_

| | +----------------------

| | |Hours before death

| | | +----------------

| | | | Skin

| | | |Smear

| | | | Culture

| | | | Animal

| | | | inoculation

| | | | +----------

| | | Age | | | | | inocu-

--------------+--------+----+-------+--------+---+-----+-----+----------

1. Sing Nu |Chinese |Male| (?) |July 11| 5 | 48 |+ + +|- - -

| | | | | | | |

Raymundo |Filipino|Male| 15 |Sept. 29| 3 | ... |0 0 0|0 0 0

| | | | | | | |

Almalas |Filipino|Male| 39 |Oct. 10| 4 | 22 |+ + +|0 0 0

| | | | | | | |

Guzman |Filipino|Male| 34 |Oct. 22| 2 | ... |0 0 0|0 0 0

| | | | | | | |

Sarmiento |Filipino|Male| 37 |Oct. 22| 3 | ... |0 0 0|0 0 0

| | | | | | | |

Gonzales |Filipino|Male| 41 |Oct. 22| 3 | 23½ |0 0 0|+ + +

| | | | | | | |

Buencamino|Filipino|Male| 31 |Oct. 22| 3 | 10 |0 0 0|0 0 0

| | | | | | | |

Nicomedes |Filipino|Male| 30 |Oct. 22| 2 | 5¾ |0 0 0|0 0 0

| | | | | | | |

Gulano |Filipino|Male| 34 |{Oct. 22| 2 |106 |0 0 0|0 0 0

| | | |{Oct. 24| 4 | 82 |0 0 0|+ + +

| | | | | | | |

Dimalanta |Filipino|Male| 35 |Oct. 23| 3 | 25½ |0 0 0|0 0 0

| | | | | | | |

Obiso |Filipino|Male| 25 |Oct. 23| 1 | 53 |0 0 0|0 0 0

| | | | | | | |

Barceta |Filipino|Male| 23 |Oct. 24| 3 | 37 |0 0 0|0 0 0

| | | | | | | |

16. Yu Tum |Chinese |Male| 14 |Oct. 24| 2 | ... |0 0 0|0 0 0

| | | | | | | |

Monterey |Filipino|Male| 29 |Nov. 1| 1 | 27 |0 0 0|0 0 0

| | | | | | | |

Pabraw |Filipino|Male| 27 |Nov. 23| 4 | 15 |+ + +|0 0 0

| | | | | | | |

Sobremonte|Filipino|Male| 20 |Dec. 7| 6 | 1 |0 0 0|0 0 0

| | | | | | | |

Marcelo |Filipino|Male| 8 |Aug. 20 |(?)| ... |0 0 0|0 0 0

| | | | | | | |

Gita |Filipino|Male| [A]17 |Nov. 24 | 3 | ... |0 0 0|0 0 0

--------------+--------+----+-------+--------+---+-----+-----+----------

[A] Months.

TABLE II.--EXAMINATION OF PLAGUE PATIENTS WHO RECOVERED

=========================================================================

|Date of examination 1912

| +-----------------------

| |Duration of disease

| | +----------------

| | | Bubo

| | |Smear

| | | Culture

| | | Animal

| | | inoculation

| | | +----------

| | | | Blood

| | | |Culture

| | | Age | | | | Aggluti-

----------------+--------+------+-------+--------+------+-----+----------

| | | | 1912 |_Days_| |

| | | |{Sept.29| 2 |- - -|0 0

| | | |{Oct. 2| 5 |+ + +|0 0

2. Dionisio |Filipino|Male | 18 |{Oct. 3| 6 |0 0 0|- +1:16

Capate | | | |{Oct. 7| 10 |- - -|0 0

| | | |{Oct. 15| 18 |- - -|- +1:64

| | | | | | |

5. Alejandra |European|Female| 6 |Oct. 20| 7 |+ + +|0 0

| | | |{Oct. 22| 2 |+ + +|+ -

| | | |{Oct. 24| 4 |+ + +|0 0

11. Gabriel |Filipino|Male | 21 |{Oct. 26| 6 |0 0 0|- +1:16

Sevilla | | | |{Nov. 8| 18 |- - -|0 0

| | | |{Nov. 15| 25 |- - -|- +1:64

| | | | | | |

| | | |{Nov. 26| 3 |+ + +|+ -

| | | |{Dec. 6| 13 |0 0 0|- +1:32

19. Esteban |Filipino|Male | 15 |{Dec. 16| 23 |- - -|- +1:60

Roa | | | |{ 1913 | | |

| | | |{Jan. 11| 48 |- - -|- +1:120

| | | | | | |

| | | |{Dec. 2| (?) |+ + +|0 0

20. Sia Su |Chinese |Male | 35 |{Dec. 5| -- |0 0 0|+ -

| | | |{Dec. 16| -- |- - -|- +1:80

| | | | | | |

24. Purificacion|Filipino|Female| 19 |{Dec. 11| 3 |+ + +|0 0

del Val | | | |{Feb. 11| 33 |- - -|0 0

----------------+--------+------+-------+--------------------------------

NOTE.--The bubo in Nos. 2, 5, and 24 never opened

spontaneously. The pus was aspirated at the time of the

second, eventually third, examination. Nos. 11 and 19 opened

spontaneously. A fistula formed along the canal which was

caused by the puncture, and healed up in several weeks. Hard

inguinal buboes of secondary order persisted in patient 19 at

the time of second examination. No plague bacilli were found

either in the bubo of the first or second order. Patient 20

had a considerable amount of pus in the inguinal primary bubo,

but it was not opened until after the last examination.

Two of the patients, cases 8 and 12, had numerous plague

bacilli in the sputum at the time when the expectoration

showed the presence of blood (twenty-three and one-half and

eighty-two hours, respectively, before death). In 3 cases I

was able to prove the presence of _Bacillus pestis_ in the

skin lesions, _intra vitam_, fifteen, twenty-two, and

forty-eight hours, respectively, before death. In case 18

there was no doubt that the skin lesions, which covered the

whole body and the face, were of secondary nature, as the

patient died shortly afterward. It was undoubtedly a case

similar to those reported by Gotschlich and Zabolotny.[5] In

the other two patients there was only 1 maculopapulous

efflorescence on the foot in case 1 (with a corresponding

femoral bubo) and 2 lesions of the same type on the arm and

forearm in case 4 (with a corresponding axillary bubo). It is

possible that these lesions were the original port of entry of

infection. Numerous plague bacilli were found in the skin

lesions of these cases, both microscopically and in culture.

[5] Kolle und Wassermann: Handbuch der pathogenen

Mikroorganismen. Gustav Fischer, Jena (1903), =2=, 521.

The plague patients tabulated in Table II recovered. They

were all treated with antiplague serum. While cases 5, 11, 19,

and 24 appeared clinically to be rather severe, cases 2 and

20 were mild.

It can be seen from the table that the plague bacilli may not

be detected in the enlarged gland at first (case 2) and that

their presence may be revealed only after repeated

examination of the bubo. It is also evident from the results

of repeated examinations that the plague bacilli disappear

from the infected gland in a comparatively short time, as a

rule at the time when pus starts to form. Contrary to the

findings in patients who died, distinct phagocytosis was

noticed in the smears made from the aspirated liquid in those

patients who recovered and who had been treated with serum

soon after the onset of the disease. It is undoubtedly this

process that clears the gland of the infectious agents.

The general opinion in regard to the presence of _Bacillus

pestis_ in the circulating blood seems to have been, as

Thompson remarks, that "the bacillus is rarely to be found in

the peripheral blood stream before the agonal stage."[6]

[6] Journ. Hyg., Cambridge (1906), =6=, 558.

The Austrian Commission, using few drops of blood, found

positive blood culture in 40 per cent; Calvert in Manila in

100 per cent when examined twenty-four hours before death;

Choksy, Berestneff, and Mayr in 45 per cent; and Greig in 60

per cent. The Indian Commission examined 28 patients, and

obtained positive blood cultures in 16 out of 23 fatal cases.

Not a single positive blood culture was obtained from the

patients who survived. The time of blood examination in

positive cases was three and one-half to seventy-five and

one-half hours before death. The amount of blood used was 1

cubic centimetre. Only 6 out of the 30 samples, which gave

positive blood culture, were found positive by microscopical

examination of blood smears. The following conclusions are

based on these observations in regard to the septicæmic stage

of bubonic plague: (1) "A severe septicæmia may be present

at a comparatively early stage of the disease and for a

considerable number of hours before death, and (2) the

septicæmia may be of an irregular and fluctuating type."[7]

[7] _Ibid._ (1907), =7=, 395.

From the tables it will be seen that out of 15 patients

examined by me, 14 gave positive blood culture; and of these

3 recovered. One blood culture revealed the presence of

streptococcus in addition to _Bacillus pestis_. The results

of the examinations tabulated in Tables I and II show, in

agreement with the findings of the Indian Commission, the

occasional early occurrence of plague bacilli in the blood

stream, as the time of examination in the positive cases

varied from one hour to one hundred six hours before death.

In consideration of the ephemeral character of the septicæmic

stage of plague, as evidenced by repeated blood cultures in

the three patients who recovered, one can hardly avoid the

impression that there is a certain degree of septicæmia in

every case of plague. The possibility of detecting the

bacillus in the circulating blood increases in proportion

with the quantity of blood used for culture. The best chance

to recover plague bacilli from the circulating blood seems to

be in the stage of high fever and general prostration.

The phenomenon of agglutination of plague bacilli by the

serum of patients was first observed by Wissokowitsch and

Zabolotny in 1897[8] and later confirmed by the German Plague

Commission. Vagedes, Klein, and others[8] pointed out the

defects of the reaction as a diagnostic means. Aside from

the technical difficulties, the reaction was found

inconstant, and its occurrence was not noticed until the

second week of the disease and even then only in low

dilutions of the serum.

[8] Referred to in Kolle und Wassermann: Handbuch der

pathogenen Mikroorganismen (1903), =2=, 524.

Although the recent work of Strong[9] and of Strong and

Teague[10] has reduced the technical difficulties, the fact

remains that positive agglutination of plague bacilli by the

patient's serum cannot be obtained in the first week of the

disease, and, therefore, the isolation of plague bacilli from

the body of the patient is still the only quick and safe

method of plague diagnosis.

[9] The Philippine Journal of Science, Sec. B. (1907), =2=,

155.

[10] _Ibid._ (1912), =7=, 194-201.

Having utilized the technic devised by Teague, I have had no

difficulty in performing the agglutination test in plague.

The emulsion of plague bacilli, to be used for the test, was

prepared by suspending young cultures of virulent plague

bacilli, grown at 30° C., in salt solution and filtering the

suspension through filter paper. No antiseptic was added nor

heat applied. Serial dilutions of unheated patient's serum

were mixed with equal amounts of bacterial suspension in

small test tubes. Incubation at 35° C. followed. Controls,

consisting of serial dilutions of normal human serum as well

as bacterial suspensions without serum, excluded any possible

error which might have been caused by spontaneous

sedimentation of the bacterial suspension; while a parallel

test with highly agglutinant serum facilitated the reading of

positive results.

Altogether, 22 tests were performed on 15 patients, 11 of

whom were fatal cases and 4 of whom recovered. In the

negative reactions, the duration of the disease at the time

of examination ranges from two to six days. The non-fatal

cases showed slight agglutination from the sixth day on. From

that day, the agglutination titer of the serum was found to

rise, and the agglutinins persisted in the blood of

convalescents up to the seventh week of the disease.[11]

[11] It is hoped that it will be possible to examine some of

the survivors for agglutination from time to time.

It must be borne in mind that the patients, who showed

positive agglutination, had been vigorously treated with

antiplague serum. Nevertheless, in consideration of the low

titer of the curative serum (dilution 1:32, agglutination

positive; dilution 1:64, agglutination negative), the rise of

the agglutinant power of the patient's serum in dilutions

higher than 1:16 cannot be explained as wholly due to passive

immunity, but rather to active immunity arrived at on the

principle of simultaneous immunization.

From the preceding observations the following conclusions are

drawn:

1. The importance of blood cultures as a diagnostic means is

evident from the fact that positive blood culture was

obtained in practically every case that was examined in the

febrile stage of the disease, even when buboes or signs of

pulmonary involvement had not been detected clinically.

2. It is also evident that _Bacillus pestis_ may be found in

the circulating blood of the patients even in cases which

subsequently recover.

3. The period of time during which _Bacillus pestis_

circulates in the blood is evidently short and irregular.

4. Mixed infection may be encountered in plague septicæmia

(_Streptococcus_, _Pneumococcus_).

5. The agglutination test is of no value for the diagnosis of

plague, as it was found positive only in convalescents.

6. Phagocytosis of plague bacilli in the bubo was noticed

only in patients who recovered after being vigorously treated

with curative serum.

7. The presence of numerous plague bacilli in comparatively

insignificant skin lesions during the life of the patient

points to the possibility of direct transmission, while the

fact that a patient without any apparent bubo, who is not so

sick as to be detained from his daily occupation, may

expectorate large numbers of plague bacilli, are facts of

great importance with regard to the communication of the

disease. It is obvious that the last-mentioned condition

might, and very likely does, give rise to an epidemic of

pneumonic plague if the atmospheric and sanitary conditions

are favorable.

TABLE III.--INSECTS FOUND TO CONTAIN BACILLUS PESTIS

======================================================================

| | |Experi-

| | |mental

Author | Insect | Source of infection |trans-

| | |mission

---------------+---------------+---------------------------+----------

Yersin |Flies |Laboratory infection |

Nuttal |Flies |Experimental infection |

Nuttal |Bedbugs |Experimental infection |Negative

| | | by bite.

Nuttal |Flea |Experimental infection |Negative.

Hankin |Ant's fæces |Fed on plague material |

Hankin |Bedbugs |Plague hospital |

Ogata |Flea |Plague rats |

Simond |Flea |Plague rats, experimental |Positive.

Tindswell, 1900|Flea |Plague rats |Negative.

Tindswell, 1903|Flea |Plague rats |Negative.

Kolle |Flea |Experimental infection |Negative.

Gauthier and |Flea |Experimental infection |Positive.

Raybaud | | |

Liston |Flea |Epidemic among pigs; |

| | harbored fleas; |

| | dead rats found |Positive.

Zirolia |Flea |Retained _Bacillus pestis_,|

| | 7-8 days |

British |Flea |Repeated experiments |Positive.

Commission | | |

Verbijtski |Flea and bedbug|Experimental infection |Positive.

La Bonadière |Fly | |

and | | |

Xanthopulides| | |

Herzog |_Pediculus |Dead body of plague case |

| capitis_ | |

---------------+---------------+---------------------------+----------

II. OBSERVATIONS ON THE TRANSMISSION OF PLAGUE BY

BLOOD-SUCKING INSECTS

Judging from the data which have been collected from the

literature[12] on the transmission of plague (Table III),

Simond seems to have been the first to call attention to

the important part which blood-sucking insects, particularly

fleas, play in the transmission of plague. Although many

investigators have been successful in demonstrating the

presence of _Bacillus pestis_ in the digestive system of

blood-sucking insects, it was not until the experiments of

Gauthier and Raybaud that the actual transmission of plague

infection by fleas was convincingly proved. Ever since the

exhaustive and conclusive experiments, which were carried out

both under natural and artificial conditions by the British

Plague Commission, and the work of Verbijtski, which antedates

the British Commission, were presented, there has been no

doubt that the transmission of plague by blood-sucking

insects, particularly by the fleas, is one, although not the

only, mode of spreading this disease. It is obvious, as Herzog

correctly remarks, that the factors which are responsible for

the spreading of plague must be considered individually in

each epidemic and in various parts of the world as well. There

is no doubt that the importance of any insect in the

transmission of plague depends on its habits as well as on

those of the host, be it either animal or man.

[12] Centralbl. f. Backt., 1 Abt. (1897), =22=, 87, 437.

Report of Indian Plague Commission (1898-99). Zeitschr. f.

Hyg. u. Infectionskrankh. (1901), =36=, 89. Kolle und

Wassermann: Handbuch der pathogenen Mikroorganismen (1903),

=2=, 538. Zeitschr. f. Hyg. u. Infectionskrankh. (1905), =51=,

268. Journ. Hyg., Cambridge (1907-10), plague numbers. _Ibid._

(1908), =8=, 162, 260.

During the recent outbreak of plague in Manila, several

samples of bed-bugs from the beds of the plague patients and

dog fleas from a plague-infected house were collected and

examined, but with negative result.

In spite of the fact that it adds nothing new to the question

of whether or not plague can be transmitted by fleas, since

the question has been conclusively answered by the work of

the Indian Commission, nevertheless the following

observations of a small outbreak of plague among animals, the

spreading of which was due solely to fleas, are of interest.

One wild rat was inoculated with strain Iloilo 3 of

_Bacillus pestis_. The skin adjoining the root of the right

ear was scarified, and a loopful of the culture was smeared

on the scarified skin. The rat was found dead three days

after the inoculation.

The cage containing the dead rat was immersed in kreolin

solution. At autopsy the cervical glands were found slightly

swollen, somewhat reddened, but no hæmorrhagic œdema of the

surrounding tissue was noticeable. There was slight necrosis

at the place of inoculation, showing superficial, purulent

discharge. Clear effusion in both pleural cavities and one

hemorrhage in the pleura were found. The lungs were

hyperæmic, but otherwise normal. The spleen was of somewhat

darker color, but otherwise normal in size and appearance.

The liver showed a slight degree of parenchymatous

degeneration, the congestion making prominent the structure

of the organ. The typical, although not constant, changes of

the organ, which are characteristic of natural plague

infection in rats, were absent. The kidneys were without

macroscopic change. The lymph glands, with exception of the

cervical nodes, were normal.

Examination of the rat's fur revealed ectoparasites on the

neck, under the chin, and back of the ears; these at the time

of the examination apparently were dead. About 6 common rat

fleas were found and identified as _Lœmopsylla cheopis_

Rothsch. The parasites were immersed in sterile salt solution

for three hours. When removed in a dry test tube, they began

to move about sluggishly. The intestinal tract of these fleas

contained blood.

Five of the fleas were crushed by means of sterile forceps,

and inserted in a pocket under the shaved skin of a

guinea-pig. The animal died of plague within three days,

showing considerable hemorrhagic œdema around the place of

inoculation, typical bilateral inguinal buboes, and

characteristic changes in the spleen. Smears and cultures

made from the bubo and spleen were positive for _Bacillus

pestis_.

Another wild rat, which was in a separate cage in the same

room where rat 1 had been kept, died twenty-four hours after

rat 1. The two cages were at least 10 centimetres apart. Rat

2 harbored fleas of the same species as were found on rat 1.

Numerous severe bites were detected back of the ears and on

the neck of the dead animal. The post-mortem findings were

identical with those described in rat 1; that is, cervical

buboes, pleural effusion, and slightly enlarged spleen.

It is well to remark that both rats had been kept in the same

room for about six months. Fleas had never been noticed on

our guinea-pigs. During the time the rats had been kept in

the plague house no irregular results were noticed in

plague-inoculated animals. At the time the first rat was

inoculated no other plague-infected animals were in the

plague house, and since that time another building has been

used for plague-infected animals.

Two days after the death of rat 2 three guinea-pigs, which

were kept in separate cages in the same room, were found dead

of plague (smears and cultures were both positive). Several

fleas (_Lœmopsylla cheopis_) were found on the necks of these

animals. They were collected and inoculated in the same way

as the fleas from the first rat. The experimental animal,

which was inoculated with the fleas, was killed and found to

be infected with plague. The findings were local reaction,

inguinal buboes, and typical spleen. Smears and cultures were

positive for _Bacillus pestis_.

Although numerous healthy guinea-pigs were examined in the

same plague house, no fleas could be found at that time, only

the 2 rats and the first 3 guinea-pigs are positively known

to have harbored fleas, the latter after the death of the

rats and not before.

The gross lesions in these naturally infected guinea-pigs

were somewhat unlike those found in guinea-pigs infected

either by vaccination or by intraperitoneal or subcutaneous

inoculation. All except one showed primary buboes on the neck

with more or less extensive hemorrhagic œdema extending in

some cases over the thorax. There was little pleural effusion

present; the spleen always showed typical changes of necrotic

foci varying in size and number. In one instance similar foci

were found also in the liver, large enough to be visible

macroscopically. This was in a case where like changes were

found in the lungs.

Only one of the guinea-pigs showed an exception, in that the

primary buboes were located in the inguinal region, with

pelvic and axillary glands secondarily involved. These are

the findings usually met within guinea-pigs artificially

infected with plague by the vaccination method, if the lower

part of the abdomen be chosen for inoculation. The reason for

such a deviation from the findings in the rest of the

guinea-pigs may lie in the fact that this animal was almost

completely deprived of hair by a skin disease.

It is of importance to mention the skin lesions which were

found on the necks of the guinea-pigs, particularly under the

chin. Besides small red spots which appeared to be fresh flea

bites, small, elevated, and fairly deep infiltrations partly

covered with moist scab were found in the skin under the

chin. Other animals showed changes usually found in the

scarified skin of guinea-pigs after artificial inoculation

with plague material. The base of each cutaneous

efflorescence was hemorrhagic and œdematous.

A histological study of the tissues of these guinea-pigs

known to be naturally infected by plague fleas showed the

following changes:

THE CERVICAL BUBO.--The enlarged lymphatic gland was

surrounded with a thickened capsule. Necrosis existed in the

subcapsular part of the gland, where it formed an almost

continuous circular zone, leaving the central part less

changed. Smaller irregular necrotic foci were scattered

throughout the section. Polymorphonuclears in various stages

of disintegration were found throughout the section.

_The Lungs._--Very few blood extravasations were present in

the alveoli; otherwise normal.

_The Spleen._--The capsule was thin. There were subcapsular

hemorrhages. The Malpighian bodies were somewhat enlarged,

but of normal structure. Throughout the parenchyma irregular

multiple necrotic foci were found, leaving but little of

spleen tissue intact. Numerous polymorphonuclears which were

present showed varying degrees of karyorrhexis.

_The Kidneys._--The outline of the cells was indefinite; a

few miliary hemorrhages existed in the cortical part of the

organ.

_The Liver._--There was excessive congestion, fatty

degeneration, and pigmentation of the cells. The capsule was

slightly thickened.

_The Skin._--The epithelium was missing in one place in the

section, and cellular infiltration extended from that place

into the subepithelial layer of the surrounding skin. The

same kind of infiltration reached deep into the skin, stripes

of cellular infiltration penetrating into the tissue along

the muscle fibres. There was no direct connection between the

cellular infiltration and the follicles of the hair.

It may be well to describe in detail the time of death from

plague among these and the other animals in this outbreak, as

well as the time when the plague house was disinfected.

The first animal (rat 1) having been inoculated on August 27,

in the afternoon, died of plague within three days (August

30). The second animal (rat 2) died twenty-four hours later.

Guinea-pigs 3, 4, and 5 (see plan) were found dead on the

morning of September 2; that is, two days after the death of

rat 2 and three days after the death of rat 1.

The same day that the three guinea-pigs were found dead of

plague, rooms I, III, IV, and VI were thoroughly disinfected.

The floor, the ceiling, and the walls were sprayed with

kerosene and lysol solution. The remaining animals in room VI

were destroyed, and the cages disinfected. No animals were

kept in rooms I, III, and IV at that time.

Three days after the death of animal 5, guinea-pigs 6 and 7

were found dead of plague, while the next day guinea-pigs 8

and 9 died. No death occurred on September 7, but the next

two days each recorded two plague guinea-pigs (10, 11, 12,

and 13). On September 11, the last guinea-pig died of plague

in this outbreak. The whole building was then thoroughly

disinfected. No plague-inoculated animals were kept in the

rooms after the first sign of the epidemic. After September

11, no more cases of spontaneous plague infection were

observed.

[Illustration: ANIMAL HOUSE]

It will be noticed that the epidemic lasted eleven days

after the first animal died and fourteen days after animal 1

was inoculated. Altogether, 14 animals out of at least 200

animals exposed died of plague.

No death occurred among rabbits, although these animals were

distributed among the guinea-pigs. In fact, 2 rabbits were

surrounded by plague guinea-pigs 8, 9, and 10, but did not

contract plague.

From the epidemiological standpoint it is interesting to know

the dimensions and location of the cages in which the animals

were kept.

Aside from the 2 rats which were confined in ordinary traps

that stood on a table 80 centimetres high, the rest of the

animals were kept in regular metal animal cages. The

dimensions of the cages are: Fifty centimetres long, 36

centimetres broad, and 30 centimetres high. The cage stands

on four legs each 10 centimetres long; the centre of the

bottom of the cage holds a drain opening 8 centimetres above

the floor.

The majority of the cages in room II were located on the

floor; some on the second shelf of a wooden rack. This

last-mentioned arrangement, judging from the construction of

the wooden frame, allowed a continuous passageway for the

fleas to the second shelf of the racks. On the other hand,

the deaths among the guinea-pigs in room V were restricted to

the cages standing on the floor, the majority of cages in

that room being placed on tables 80 centimetres high.

Only a theoretical explanation can be given of the short

duration and sudden cessation of the outbreak. One can assume

with great probability that the first partial disinfection

drove the fleas away from the primary source of infection,

and that they traveled as far as possible. They finally

settled in those guinea-pig cages which had not been molested

by the first disinfection. Having no new supply of plague

blood (all of the plague-infected guinea-pigs having been

removed, most of them before death), the fleas soon cleared

themselves of plague bacilli. The peculiar feature of the

outbreak, namely, the failure to find fleas on the animals in

rooms II and V, finds its explanation in the observation of

the Indian Commission who found that the fleas "died or

disappeared very rapidly."

The following conclusions can be drawn from these

observations:

1. The common rat flea (_Lœmopsylla cheopis_) prefers the rat

to the guinea-pig.

2. In the absence of rats it will attack guinea-pigs rather

than rabbits.

3. The fleas which have sucked blood from rats or guinea-pigs

afflicted with plague septicæmia were found to harbor

virulent plague bacilli inside of their bodies.

4. The transmission of plague infection by direct or indirect

contact being excluded in our case, the fact that fleas of

the same species and harboring plague bacilli were found on

the rat and on the guinea-pigs, the presence of flea bites on

the rats and on the guinea-pigs with positive findings of

skin lesions on that part of the body where the fleas and

flea bites were located, together with the anatomical picture

of the findings in the guinea-pigs, lead to but one

explanation; namely, that the plague infection was

transmitted by fleas.

III. OBSERVATIONS ON ANIMALS SUSPECTED OF PLAGUE

Out of the several tens of thousands of rodents examined

during the antirat campaign, we have found only two plague

rats which showed the typical picture of natural plague

infection in rat; that is, cervical buboes with surrounding

œdema, subcutaneous injection, pleural effusion, enlarged

spleen, and such changes of the liver as are characteristic

of natural plague infection in rats. Microscopically, large

numbers of plague bacilli were found in these cases, and pure

cultures of _Bacillus pestis_ were recovered from the spleen.

Histological examination of internal organs, particularly

that of the liver, confirmed the bacteriological findings.

The remainder of the plague rats exhibited only two of the

signs of plague infection, namely, bubo and œdema of the

surrounding tissue, and eventually hemorrhages.

Besides plague infection, a great number of rats showed

purulent conditions from causes other than plague. Abscesses

of the lungs were frequently met with, and cervical or

axillary buboes are not uncommon in Manila rats. Various

pyogenic bacteria were found in the pus of such abscesses. Of

the less common was _Bacillus pyocyaneus_ and the

pneumobacillus of Friedländer. Chronic plague was excluded in

these cases since the animal inoculation failed to produce

plague infection.

More than half of the rats examined harbored parasites in

their organs. _Echinococcus taeniæformis_ was found in the

liver of practically every gray rat, while a small _Ascaris_

and _Tænia diminuta_ were not uncommon in the intestines. Two

rats were found to have sarcosporidiosis, 2.6 per cent.

showed rat leprosy, and 7.4 per cent. trypanosomiasis. One

tumor of the mammary gland and one tumor in the axillary

region were encountered, while one tumor of the large

curvature of the stomach proved to be a chronic inflammatory

tumor due to parasites. One peritoneal tumor in a rat (_Mus

decumanus_) gave the impression of a malignant tumor on

account of the miliary dissemination of the peritoneum. It

was found to consist of muscle and spindle-cell sarcomatous

tissue. Ectoparasites were very seldom noticed, on account of

the method of collecting the rats. When present, they were

mites and fleas.

In the naturally infected plague rats the rigidity of the

fresh cadaver was pronounced. The primary bubo was in every

case cervical. Cervical glands were enlarged and hemorrhagic

with slight œdema of the surrounding tissue. The subcutaneous

injection extended over the neck and chest. The inguinal

glands were small and pigmented. The lungs were collapsed,

and showed hemorrhagic foci. The spleen was slightly

enlarged, firm, and dark red. The liver was rather large,

firm, pale red, with shade of yellow, which was caused by

minute yellowish foci thickly scattered throughout the tissue

and visible through the capsule. The kidneys were hyperæmic.

The intestines were without change. The serous membranes were

pale with no hemorrhages.

Histological examination of the tissue of naturally infected

plague rats showed the following changes:

_Liver._--The structure of the organ was well marked; the

veins dilated, trabeculæ slightly compressed, nuclei well

stained, and few of the liver cells showed vacuoles. Small

foci, most numerous under Glisson's capsule, were scattered

throughout the organ; they varied in size, but were not

larger than a miliary tubercle. The small necrotic foci were

found to consist of few necrotic liver cells. The centre of

the larger foci was formed by degenerated and necrotic liver

tissue, surrounded by round-cell infiltration.

Polymorphonuclears were also found in the zone of cellular

infiltration. There was a slight degree of hemorrhage in

each focus. Epithelioid cells and large vesicular cells with

several nuclei were to be found. The foci, mentioned above,

were sharply demarcated from the surrounding liver tissue,

which appeared to be intact.

_Spleen._--The structure was well preserved, the capsule

thin. The Malpighian bodies were normal as to the elements of

which they consist. Cells with pycnotic nuclei were scattered

throughout the organ, and vesicular cells with small, deeply

stained, excentrically located nuclei were present.

Polymorphonuclears were found in the tissue in considerable

numbers. No localized necrotic foci could be found in

sections through the spleen.

_Cervical Glands._--The blood-vessels were considerably

distended. A few hemorrhages and polymorphonuclears were

present. Œdema of the capsules and surrounding tissue

existed. Part of the gland was necrotic.

_Lungs._--The blood-vessels were distended. The alveoli

contained homogeneous masses and blood. There were numerous

subpleural hemorrhages. The bronchi were collapsed, and

contained mucus.

_Kidneys._--The cortical part showed subdued structure; the

epithelial cells had an indefinite outline and occasionally

showed vacuolization. The medullar part was better preserved.

There were miliary subcapsular hemorrhages. A few small foci

were scattered throughout both medullar and cortical parts.

They consisted of round-cell infiltration.

NATURAL PLAGUE INFECTION IN A CAT

The experiments of the German Plague Commission proved that

cats showed considerable resistance to plague infection as

cutaneous and subcutaneous inoculations failed to infect

them. According to the Austrian Commission, cats develop

submaxillary buboes if fed on plague material. They are said

by Albrecht and Gohn[13] sometimes to recover. Out of four

cats fed on plague material two died of plague, one showing

submaxillary, the other mesenterial buboes. Virulent plague

bacilli were found in the discharge from the nose and also in

the fæces of cats which apparently did not become infected

after having been fed on plague material.

[13] Über die Beulenpest in Bombay im Jahre 1897 (1897), II

B, II C.

One case of spontaneous plague infection of a cat was

recorded by Thompson[14] in Sydney.

[14] Report of an outbreak in Sydney, 1900. Referred to in

Kolle and Wassermann (1903), =2=, 510.

W. Hunter,[15] in Hongkong made observations on cats

suffering from plague infection. The author also undertook a

few experiments, and arrived at the following conclusions:

1. Cats suffer from plague.

2. The disease may be acute or chronic.

3. The type of the disease is septicæmic.

4. The animals may occasionally play a part in the

dissemination of plague.

5. In plague-infected areas cats probably become infected

through rats, which they devour as food.

6. In plague-infected districts possible plague infection in

cats is of great importance from a domestic point of view.

[15] Lancet (1905), =I=, 1064.

On November 27, 1912, a sick cat was brought to the

laboratory for examination. It was reported that the animal

was found in a warehouse in which dead rats had been found

some time previously. The rats were not examined. In the

morning of the 30th, the cat was found dead in the cage where

it had been kept under observation. The following are the

post-mortem findings:

The animal was a fairly well-nourished female.[16] The

subcutaneous tissue, pericardium, mediastinum, and

mesenterium contained considerable amounts of fat.

[16] The cat was the mother of 4 kittens which were about 3

weeks old at the time the cat was delivered for examination.

They were kept under observation for several weeks, but

showed no signs of plague infection.

The subcutaneous tissue of the neck showed œdema and small

hemorrhages. The submaxillary tissues were swollen on both

sides. When the fasciæ and superficial muscles of the neck

were removed, enlarged glands were found on both sides. These

were closely attached to the submaxillary salivary glands.

The surrounding tissue was œdematous, but no hemorrhages were

noticed in the vicinity of the enlarged glands. Upon section

the glands were found to be necrotic, and upon pressure a

thin purulent liquid escaped. There were no hemorrhages

within the glands. Several enlarged lymph-nodes, smaller in

size, could be followed down the neck on the left side. The

lymph-nodes in the axillæ as well as in the groins and

peribronchial nodes were normal. The mesenteric glands were

slightly enlarged and reddened.

The lungs were slightly collapsed. A clear, sanguineous,

slightly coagulated effusion was observed in both pleural

cavities. The tissue of the lungs showed considerable œdema

and hypostasis. The bronchi and pharynx showed no changes,

the mucous membrane being pale and thin.

The heart was normal.

The spleen was enlarged, of light red color, with follicles

slightly prominent.

The stomach contents was blackish in color; there were no

hemorrhages or ulcers in the mucosa.

The liver was somewhat enlarged. The organ showed prominent

structure, the centres of the acini being red, the periphery

lighter in color.

The kidneys were slightly enlarged and pale. The capsule

peeled off easily, the venæ stellatæ were prominent, the

surface smooth; there were no hemorrhages. The cortex was

increased in breadth and was of the same color as the

surface; the pyramids were darker in color. The organ was of

fragile consistence.

Suprarenals were normal, as were also intestine and bladder.

The histological findings were as follows:

_Bubo._--The capsule of the gland was œdematous. The whole

gland as seen in cross section had undergone necrosis, except

a few foci which still showed cellular structure.

_Lungs._--The alveoli were filled with homogeneous masses,

containing but few degenerated epithelial cells and

leucocytes. The blood-vessels were dilated, particularly in

the subpleural part of the organ. In some places capillary

mycotic emboli with subsequent hemorrhage were encountered.

The large blood-vessels and bronchi were normal.

_Salivary Glands._--Those glands attached to the primary bubo

showed the normal structure of a combined mucous and serous

gland.

_Liver._--There was considerable congestion. The centres of

the acini showed parenchymatous and fatty degeneration. The

cells on the periphery of the acini exhibited typical fatty

infiltration. The large blood-vessels and small ducts were

without change.

_Kidney._--The cells of the kidney showed various degrees of

degeneration, ranging from parenchymatous to fatty

infiltration. There were a few capillary hemorrhages and

hyaline casts present.

_Suprarenals._--These showed slight degeneration.

_Spleen._--This organ showed congestion, a few hemorrhages,

and bacterial emboli; otherwise normal.

The bacteriological examination of the material from this cat

gave the following results:

1. _Smears:_

_a._ From the buboes showed degenerated leucocytes, many

lymphocytes, and numerous bacteria, some of which resembled

_Bacillus pestis_ in their polar staining.

_b._ From the spleen showed numerous plague-like,

polar-stained bacilli. Round involution forms were present.

2. _Cultures:_

_a._ From the buboes were badly contaminated with _Bacillus

coli_ and _Bacillus pyocyaneus_ colonies.

_b._ From the spleen: A few scattered colonies of _Bacillus

pyocyaneus_ developed on the surface of the agar. Between the

large colonies a scanty growth of dewy appearance was

noticed. Smears made from this growth revealed plague-like

bacilli of the cultural type, showing a few club-shaped

involution forms. Subcultures were made in order to secure

pure culture. They showed a pure growth of _Bacillus pestis_

as indicated by the morphology of bacilli and shape of the

colonies. Agglutination with plague-immune serum was

positive.

3. _Inoculation experiments (vaccination method):_

_a._ One guinea-pig was inoculated with the material from the

left bubo, another one with material from the right bubo.

They died of plague on the third and fifth days,

respectively.

_b._ One guinea-pig was inoculated with the material from the

spleen. It died of plague on the third day.

_c._ One guinea-pig was inoculated with material from the

nostrils obtained by swab. The animal survived, showing no

indication of plague.

_d._ One guinea-pig was inoculated with material from the

rectum obtained by swab. It died of plague on the fifth day.

Although plague infection among cats is apparently a rare

occurrence, the fact that cats may contract the disease in

spite of the high degree of resistance to plague infection

has to be considered from the hygienic standpoint.

To appreciate the important rôle which cats may play in the

spreading of the disease one need only consider the close

contact of these animals with rats on one side and human

beings on the other. It is also a well-established fact that

not only plague-infected cats, but also those which have

devoured plague-infected material and remained apparently

normal, may excrete plague bacilli which have retained their

full virulence.

NOTES ON PLAGUE IN HONG KONG BY DR. ROBERG.--During the Hong Kong

epidemic of plague which preceded and was coincident with that of

Manila, I visited that city twice (December, 1913, and July, 1914), but

I did not closely investigate the methods adopted and carried out by

the authorities there, for the reason that the Manila plan was so much

more productive of results, as shown by the apparent inability of the

Hong Kong officials to gain control of the disease. However, I received

from Dr. David Roberg, of the Oregon State Board of Health, a copy of a

report made by him to the Secretary of his State Board of Health,

following an investigation of the Hong Kong epidemic and the methods

there followed. I have Dr. Roberg's permission to use his report and it

is herewith presented. It is dated Manila, April 16, 1914, and is as

follows:

I have the following notes to present on the epidemic of

bubonic plague in Hongkong.

On April 5th when I arrived in Hongkong the epidemic was

rapidly approaching its height. With its onset in January

there were 47 cases, in February 42, and in March 223. During

the week previous to April 5th, there were 91 cases; during

the six days I was in Hongkong they averaged 15 a day.

Judging from previous epidemics the present one will be

exceptionally severe. The season for the occurrence of human

plague is from the months of February to July. The onset is

gradual; in May it reaches its maximum and then declines. In

the epidemic of 1912, for the city of Victoria the monthly

rate showed the following, January 9, February 22, March 61,

April 265, May 513, June 346, July 105, August 11, and

September 1. Comparing these rates with those of the present

year it will be seen that the number for March far exceeds

that of two years previous.

Illustrating the season for human plague, with its onset,

maximum and decline, are the monthly rates for the city of

Kowloon during 1912, when the following cases occurred:

February 2, March 12, April 52, May 246, June 152, July 39,

August 8, and September 3.

The season for human cases is determined by the condition of

the rats. At the close of the season in July the rats die off

from plague in great numbers as it is then the hottest time

of the year. During the months from September to February the

rats increase in number and in susceptibility to the extent

of being sufficient to again infect human beings. Moreover

every other year shows a marked severity in the epidemics of

human bubonic plague. This is explained by the fact that it

requires two years' time for the rat population to become of

sufficient greatness and susceptibility to cause a severe

human outbreak. This is shown by the yearly number of cases

since the year 1911. During the years 1911, 1912 and 1913

respectively, there were 253, 1847, and 408 cases. During the

present year the monthly rate is exceeding that of the heavy

year of 1912.

The severe epidemic in 1912 was a result of the influx of

50,000 Chinese refugees into Hongkong during the revolution

in 1911. The number of rats in the native district depends

upon the available food supply, and as a result of this human

overcrowding the amount of waste food so increased in the

houses, yards and streets, that the over accumulation of

garbage could not be kept pace with. This influx also brought

in great numbers of susceptible rats.

The number of rats killed off during the epidemic in 1912

were so great that in 1913 they had not recovered

sufficiently to cause a severe outbreak during that year, and

as a result of the lightness of epidemic in 1913, they are so

increased in number and susceptibility now that they are

causing a very severe epidemic in human beings.

Of rats in Hongkong they have the _Mus decumanus_ or drain

rat and the _Mus rattus_ or house rat. It is noteworthy that

the drain rat is found plague-infected throughout the year,

while the house rat is found infected only during the period

in which the human epidemics occur, namely from February to

July. The number of infected rats a year run parallel to the

number of monthly cases.

The bulk of human infection is due to the spread of house

rats. Man also becomes infected by the drain rat when the

drains are flooded by rain storms and the rats are driven

into the houses.

What has made plague permanent in Hongkong is the

overcrowding of the native districts. Besides there is a

floating population entering and leaving the native quarters,

numbering about 4000 a day. The native houses have been built

with double floors and walls which harbor the rats. Where the

construction is of wood it is possible to remove the rat

spaces. It has been found since the introduction of plague

into Hongkong in 1894, that those districts containing the

greatest number of soft brick houses with hollow walls, have

shown the greatest incidence of plague. This can not be

remedied as it would involve the destruction of buildings on

too large a scale.

THE WORK OF THE SANITARY BOARD

The area under the control of the Board comprises the Island

of Hongkong containing 32 square miles, with a sea frontage

of 13 miles in length. Included also is the old city of

Kowloon which is situated one mile and a third across the

harbor and contains two and three-fourths square miles. The

city of Victoria on the northern shore of the Island of

Hongkong has a sea frontage of 5 miles, contains about ten

thousand domestic buildings, of which about one thousand are

non-Chinese.

The population of Hongkong is difficult to estimate, as the

floating population is so great. In the 1912 census there

were 446,614 Chinese and 21,163 non-Chinese.

The city of Victoria is divided into 10 Urban Health

Districts and old Kowloon into 2. There is an inspector in

charge of each. These districts are built over an area

averaging from 31 to 140 acres. The houses in these districts

average one thousand and the population from 8000 to 33,000.

There are four inspectors in charge of the scavenging work,

one for the disinfection stations in Victoria and old

Kowloon, one for the cemeteries and two for general duty.

The measures employed by the Sanitary Board are summarized as

follows:

1. The exclusion of rats from all dwellings by means of

concreted ground surfaces, the protection of all drain

openings and ventilating openings by iron gratings, and the

prohibition of ceilings and of hollow walls in new buildings

and in those existing buildings from which they have been

removed by order.

2. The collection and bacteriological examination of all dead

rats. Facilities for the collection of rats in the quarters

are provided in the shape of small covered bins attached to

lamp posts, telephone posts, electric light poles, etc. These

bins contain a carbolic acid disinfectant, and the

inhabitants are invited to at once put into them all rats

found or killed by them. There are 650 of these bins

distributed throughout the city and its suburbs, and each of

them is visited twice daily by rat collectors who take all

rats found by them to the City Bacteriologist. Each rat is at

once labelled with the number of the bin from which it is

taken, and if subsequently found to be plague infected, a

special survey is immediately made of the block of houses in

that vicinity. All rat-holes and rat runs are filled up with

broken glass and cement, defective gratings and drains dealt

with, and rat poison distributed free to the occupants. If

several plague-infected rats are found in one locality, a

special house-to-house survey and cleansing of that district

is made.

3. The destruction of rats by poison, traps and birdlime

boards; special efforts in this direction being made just

before the onset of the regular plague season which is in the

months of from March to July.

4. The encouraging of the community to keep cats.

5. The systematic cleaning and washing out of all native

dwellings at least once in three months with a flea killing

mixture made by emulsifying kerosene in water.

6. An efficient daily scavenging of all streets and lanes

and the daily removal of refuse from the houses, coupled

with the provision of covered metal dust-bins, to reduce as

far as possible the amount of food available for rats.

7. The disinfection of plague-infected premises by stripping

them and washing them out thoroughly with a kerosene

emulsion. The bedding, clothing, carpets, rugs, etc., are

conveyed in a huge covered basket to the disinfecting plant

and sterilized with superheated steam. No objection is made

to the treatment of plague cases in native hospitals, and no

restrictions are imposed in regard to the burial of those

dead with plague except the provision of a substantial

coffin.

8. Every effort is made by means of lectures, addresses and

explanations to induce the native population to participate

in the above preventive measures.

Upon my last visit to Hong Kong, in July last, plague was abating. _The

South China Morning Post_ of July 15, 1914, contained the following

statement:

Plague is gradually disappearing from Hongkong. Last week's

return shows that there were 26 cases, of which 19 were fatal.

All were Chinese. The total number of cases for the current

year to date is 2093, with 1939 deaths resulting.

I regret that circumstances do not permit me to relate in detail the

work done and the observations made during the closing six months of

the Manila epidemic.

Up to the day of my departure from the Philippines, in July, 1914, I

remained in charge of plague suppression, but the added duties of

administration at San Lazaro Hospital and the coincident occurrence of

a cholera epidemic prevented me from keeping a detailed record in such

form as to permit reproduction here. It will therefore suffice to say

that the first six months of 1914 witnessed the passing of the most

threatening situation that has confronted the city of Manila in years.

The record of plague rats found does not convey an accurate idea of the

prevalence of rat plague by any means, for the simple reason that, when

found, the rat cadavers were in such condition as to forbid

bacteriologic examination; and inasmuch as the bacteriologic test of

plague had been used exclusively in determining rat plague up to this

time, it seemed desirable to adhere to the original method.

In February we found in one of the districts, in which we undertook

systematic work in consequence of a few cases of human plague, a very

large number of dead rats, in and adjacent to houses which furnished

human plague cases. In one building alone more than 150 rat cadavers

were found during our cleaning and rat-proofing operations. It is this

district concerning which the letter to the public (already quoted) was

written.

The methods followed in treating this new and dangerous focus of

infection did not differ from those practised during the previous year,

except in the matter of intensity. Forces of the cleaning and

rat-catching gangs were increased and the utmost thoroughness of

treatment was insisted upon. The results fully justified our policy and

demonstrated again how feasible it is to fight plague successfully if

adequate authority be given.

During the last year of the epidemic in Manila it became the rule for

us to expect our plague workers to locate and find the identical rat

cadaver from which the infected fleas bore the disease to the human

victim, provided the spot upon the floor where the patient's sleeping

mat had been placed was known. In the better class of houses the rat

(sometimes more than one) was found dead beneath the floor, behind some

post casing, or in other space caused by double construction. Time and

again I have directed the removal of some panel of woodwork, some post

casing, or a board of the floor with the full expectation (seldom

unrealized) of finding a dead rat or a rat nest. These experiences were

positively uncanny at times. In the houses of the poorer class, usually

of bamboo and thatch construction, the finding of the rat was less easy

and more uncertain, although the nest was repeatedly found, and as

related elsewhere the dead rat itself might be found in a hollow bamboo

timber, or in the thatch construction of the wall. In a house on Calle

Echague, from which a Filipino and his wife were removed, dead, within

a few hours of each other, several dead rats were found in the floor

(the only piece of double construction in the whole house) within four

feet from the spot where the sleeping mats were placed. A rat hole led

to the nest and through this hole the fleas from the dead rats found

their way to the human victims sleeping on the floor above the encased

nest.

These instances could be multiplied many times, but there is no longer

any special reason to do so, as the rat and the rat-flea are so

completely incriminated as to render these repetitions quite

unnecessary, however interesting they may be to the plague worker. The

danger of pursuing these investigations, to the persons so engaged,

must not be lost sight of, and exposure of such nests and rat cadavers

should invariably be preceded by thorough spraying of the place, and

particularly of the spot where tearing out of double construction is to

be done. I know of no more dangerous employment than this, both for

laborer and bystander.

Plague Its Cause and the Manner of its Extension, Its Menace, Its Control and Suppression, Its Diagnosis and Treatment · 第 4 / 5 章

Simplicio Enriques, aged twenty-seven, a silversmith,