on all the ordinary media. In bouillon it produces a uniform
cloudiness in twenty-four hours. A slight scum forms after several
days’ growth, which falls to the bottom when shaken. In Dunham’s
solution it grows well, but produces no indol in twenty-four hours’
growth.
It does not coagulate milk.
It grows the whole length of the stab in gelatin, forming small
whitish colonies in the deeper portions of the tube. It does not grow
over the entire surface of the gelatin tube; does not liquefy gelatin.
It grows under anærobic conditions.
It ferments glucose bouillon, but not lactose bouillon. In glucose
bouillon it produces 1-CO_{2}, 5-H. It also produces H_{2}S.
From a general biological standpoint it is plain that this bacillus
belongs to the para-typhoid group, and is very similar to the bacillus
of hog cholera as well as the _Bacillus icteroides_, also _B.
enteritidis_, so far as its morphological and cultural characteristics
are concerned.
In the following table the fermentations produced by various members
of this group upon certain carbohydrates are shown:
─────────────┬────────┬───────────┬────────┬────────┬────────┬─────────
Organism. │Lactose.│Saccharose.│Maltose.│Mannete.│Glucose.│Levulose.
─────────────┼────────┼───────────┼────────┼────────┼────────┼─────────
B. typhosus │ − │ − │ − │ − │ − │ −
B. dysenteriæ│ − │ − │ − │ − │ − │ [AT]
Shiga │ │ │ │ │ │
B. dysenteriæ│ − │ − │ − │ − │ − │ [AT]
Kruse │ │ │ │ │ │
B. │ │ │ │ │ │
para-typhosus│ − │ − │ + │ + │ + │ +
A │ │ │ │ │ │
B. │ │ │ │ │ │
para-typhosus│ − │ − │ + │ + │ + │ +
B │ │ │ │ │ │
B. para colon│ − │ − │ + │ + │ + │ +
B. acidi │ + │ − │ + │ + │ + │ +
lactici │ │ │ │ │ │
B. hog │ − │ − │ + │ + │ + │ +
cholera │ │ │ │ │ │
B. typhi │ − │ − │ + │ + │ + │ +
murium Danysz│ │ │ │ │ │
B. icteroides│ − │ − │ + │ + │ + │ +
B. │ − │ − │ + │ + │ + │ +
enteritidis │ │ │ │ │ │
B. coli │ + │ + │ + │ + │ + │ +
communis │ │ │ │ │ │
─────────────┴────────┴───────────┴────────┴────────┴────────┴─────────
Footnote AT:
Or bubble.
EXPERIMENTS UPON RAT VIRUS IN THE HYGIENIC LABORATORY.
In 1901 I made an investigation of this pathogenic microbe (_B. typhi
murium_) applied to the destruction of rats under laboratory
conditions.[AU] One hundred and fifteen rats were fed with the
cultures in various ways during the course of these experiments with
the virus. Of these, 46 died—less than half.
Footnote AU:
Rosenau, M. J.: An investigation of a pathogenic microbe (_B. typhi
murium_ Danysz) applied to the destruction of rats. Bull. No. 5 of
the Hygienic Laboratory, U. S. Mar. Hosp. Serv., Washington, 1901,
11 p.
Most of the rats used were the gray rat (_M. decumanus_ or
_norvegicus_) and the tame white rat. A few (8) of the wild black or
house rats (_M. rattus_) were used.
The virus is in reality pathogenic for these three kinds of rats when
ingested. No special difference was noted in its effects upon the
various species.
As the work progressed it soon became evident to me that the result
depended largely upon the amount of the culture ingested. By starving
rats for a day or two and then giving them all they could be induced
to eat and drink of the cultures, a very positive result was obtained.
In one instance of 27 rats so fed all died within a week. If the rats
are given a small amount the effect is uncertain—only a few die. In
one instance I fed 70 rats with 4 agar tubes and only 7 died. Feeding
them a second time with very large quantities 9 more died. The
survivors were then fed with all they could be induced to eat every
day for a week without effect.
It seems plain, therefore, that a large primary dose proves fatal, and
a small dose is not only uncertain, but produces an immunity. This is
a very important factor, for it is likely that in the wild state rats
would often partake of an amount too small to cause death. Such rats
may then subsequently eat large amounts of the culture with impunity.
It would seem then that, after all, the virus is not so different from
the laying of a chemical poison, depending as it does for its effect
upon the amount ingested. A chemical poison, however, does not possess
the disadvantage of producing an immunity. Another disadvantage
possessed by the virus is the rapid deterioration in virulence which
occurs when it is exposed to the action of air and light, or when it
becomes dry, as is very apt to happen when laid out for rats in the
wild state.
Since these early experiments, tests have been made of various rat
viruses in the Hygienic Laboratory, and the results are given in the
following pages:
AZOA.
Series 1. Single feeding of azoa in oatmeal. Rats starved twenty-four
hours before feeding. Three out of eight animals died in four, five,
and seven days, respectively. Micro-organisms resembling the
predominant one of azoa could not be isolated from their hearts’
blood. The organs of these dead rats were fed to fresh rats with the
result that one of the three died. It must be mentioned that the
mortality among our fresh rats was nearly as high as that in the
experimental animals from a disease probably due to infection with an
animal parasite.
Series 2. Daily feedings with azoa in oatmeal. Five white rats fed
with the mixture, a constant supply being kept in the cage. These
animals were picked rats freshly obtained from the dealer. One rat
died after seven days. It was heavily infested with lice. The azoa
organism could not be found in the blood. The rest remained well after
twenty-five days.
Series 3. Black tame mice, daily feedings. One of the five died after
seven days. The rest remained well after fourteen days.
These experiments indicate that azoa is not pathogenic for white rats
and black tame mice to a degree rendering it applicable for vermin
extermination on a practical scale, provided that its action is no
more pathogenic for the wild than for the tame species.
RATITE.
The manufacturers recommend a single feeding of this substance rather
than a continued exhibition of the virus.
Series 1. Five white rats starved twenty-four hours and then fed with
a mixture of ratite and oatmeal. Subsequent daily feedings with plain
oatmeal. Picked animals fresh from the dealer. One animal died after
twelve days; too much putrefied for further examination; had been
heavily infested with lice. The remaining rats are well after
twenty-five days.
Series 2. Five black tame mice fed as above. Three were found dead
after eighteen days and the other two after nineteen days. Further
experiments were not made, as putrefaction was too far advanced when
they were found. The room in which they were kept had been unusually
cold just before their death owing to a sudden and unexpected drop in
the external temperature.
Ratite does not appear to be very pathogenic for white rats. All the
five mice fed with ratite died in eighteen to nineteen days (much
longer than the advertised incubation period of the infection), but
their death could be reasonably attributed to unusual cold. This part
of the test is therefore invalidated except that the animals lived
considerably longer than would be expected from the literature
furnished by the manufacturers, which says that the effects of laying
the virus will be apparent in eight to ten days.
DANYSZ VIRUS.
Twelve tubes of Danysz virus were sent to the laboratory for
examination April 7 by the Independent Chemical Company, agent for
Danysz Virus Company (Limited). The label stated “Keep in a cool place
and at above temperature; use before May 15, 1909.”
The virus was kept at 15° C. until April 13, when it was turned over
to Passed Asst. Surg. W. H. Frost, who made the following tests:
One tube opened. Cultures made on two agar tubes were found to
correspond in cultural characteristics with the bacillus of Danysz
virus as generally described. The remainder of the tube prepared
according to directions in accompanying circular, using stale dry
bread 2 ounces and suspension of the culture in normal salt solution.
Series 1. Approximately equal parts, then fed to six white rats in
individual cages, they having not been fed for twenty-four hours
previously. Rats all ate greater part of infected food.
Five rats of series 1 died within five to seven days and were partly
eaten before being removed from the cage. The pathological changes in
all cases were chiefly enlargement and congestion of spleen and liver,
and in some cases inflammation of small intestine. In each case an
organism was obtained, usually in pure culture, from one or more
organs, corresponding culturally and morphologically with cultures
taken from original tube.
Series 2. April 14: Rats all ate greater part of infected food.
Transferred to large cage containing nine other white rats. Nine other
white rats exposed to infection by being placed in a large cage with
the rats of series 1. Four of the nine rats of this series died in
four to seven days after eating infected rats.
Pathological changes and results of cultures from internal organs the
same as with series 1. Autopsy and cultures impossible in one case,
where body was almost completely devoured.
Series 3. May 5: Three of the six surviving rats (one from series 1,
two from series 2) were placed in individual cages, deprived of food
for twenty-four hours, then fed each with one-third agar tube cultures
of Danysz virus (the same used in the original feeding). All three ate
practically all the virus given.
All three of these rats remain alive and well after two months.
Summary.—Series 1. Six rats each fed one-twelfth to one-sixteenth agar
culture Danysz virus. Five died within five to seven days.
Series 2. Nine rats exposed to infection by being placed in cage with
series 1. Four died within eight to twelve days after death of first
rat of series 1.
Series 3. Three of the surviving rats (1 from series 1 and 2 from
series 2) fed each with one-third agar tube of original Danysz virus
as used in series 1. None died.
TRANSATLANTIC RATIN.
A can of this substance labeled “Transatlantic ratin” was furnished by
the American agents representing the Bacteriological Laboratory,
Copenhagen, Denmark. The can bore the date January 26, 1909, and was
stated to be “effective for six months from date of production.”
On April 13, 1909, this sample was given to Passed Asst. Surg. W. H.
Frost for examination, and he obtained the following results:
April 13, 1909: Can of ratin opened with aseptic precautions. Contents
mixed with about equal bulk of clean fresh lard.
A portion of this about equal to one tablespoonful fed to each of six
white rats previously deprived of food for twenty-four hours. All the
rats ate some of the bait at once. Feeding at 2 p. m.
April 14: Five rats very sick, having convulsions; partially
paralyzed. One dead.
April 15: Three more rats found dead. Remaining 2 recovering.
The pathological change in all the above cases consisted chiefly of
intense congestion of intestines, both large and small.
Cultures from the original case of ratin, on agar, bouillon, and in
fermentation tubes, negative except staphylococcus in one tube.
Cultures taken from heart’s blood and other organs of the 4 dead rats
all negative, except in one case a growth of a staphylococcus
resembling _S. pyogenes citreus_.
April 20: Two rats fed on half agar slant culture of the
staphylococcus obtained from heart’s blood of rat No. 1. Result of
feeding negative after several weeks.
NOTE. The absence of a colon-like organism in this virus and the
rapid death of the animals with convulsions suggested a chemical
poison, which it is believed this can contained.—M. J. R.
EXPERIMENTS WITH MICRO-ORGANISMS FOR DESTROYING RATS, CONDUCTED BY THE
UNITED STATES BIOLOGICAL SURVEY.[AV]
Footnote AV:
This report was furnished by Dr. A. Hart Merriam, Director of the
Biological Survey.
RATIN.
The Biological Survey, Department of Agriculture, in cooperation with
the Bureau of Animal Industry, has experimented with “ratin.” The
material (ratin No. 2—labeled “Transatlantic ratin”) was furnished by
the American agents in New York. Although the agent claimed that this
was a bacterial preparation and that “it would kill for six
generations,” it proved to be a glucoside poison (probably squills)
and contained no bacteria of any kind. A number of experiments were
made with it, and it proved to be an effective rat poison. In some
instances the animals died within two hours after eating it, and in
two experiments all the animals fed died within twelve hours. In other
experiments, however, a considerable percentage of the affected rats
recovered, and subsequent attempts to kill them with ratin No. 2
failed. Some were immune to its effects and others too wise to eat it
a second time. More than a hundred rats were used in the experiments;
but the main object—to test the communicability of the disease caused
by ratin bacteria in healthy rats—failed, of course, since, as above
stated, the preparation experimented with contained no bacteria, but
was merely a vegetable poison. Before its character was fully
determined, 15 rats killed in the experiments were eaten by 5 healthy
rats; the latter were unaffected.
It should be noted that the labels on the tins containing
transatlantic ratin were misleading. The user was warned to open the
packages in dim light and to allow no moisture to come in contact with
the contents, as the bacteria were very sensitive to light and
moisture. The contents of the can were to be used at once. As a matter
of fact the contents of one can were exposed to severe drying in heat
and sunlight for four days and then soaked in water for two days.
Afterwards the preparation was fed to different rats for a further
period of four days, and its virulence was retained to the last.
The transatlantic ratin is in a solid medium, apparently bread and
molasses. Its keeping qualities are excellent, and it is an effective
poison for rats, but far too expensive for extensive use. A can
costing $1.50 is enough for only 15 baits.
Its harmfulness to domestic animals was not fully tested. Dogs and
cats refused to eat it and vomited it when it was forced upon them.
Several animals, including a dog, were killed by injections of the
poison in concentrated form.
A shipment of ratin No. 1 (the solid bacterial ratin, said to retain
its virulence for two months) was received June 4, 1909. This
preparation was dated May 8 and should have been still virulent. The
contents of a can mixed with milk was fed to 8 adult rats on June 7.
All of the baits were eaten, but no result followed. Cultures of the
bacteria showed strong growths of new colonies.
On July 6 the contents of another can were fed to 1 adult and 16 young
rats. One of the young was found dead on the morning of July 14.
Cultures were made from the dead rat, but the bacillus was not
recovered. Up to July 28 none of the other rats have been affected.
AZOA.
Several trials of azoa for the destruction of rats have come under the
observation of members of the Biological Survey. Experiments made in
the building occupied by the Interstate Commerce Commission were at
first promising, but from a second invoice of the virus no results
were obtained. In the buildings of the National Zoological Park 72
bottles of azoa were used, but the results were for the most part
negative. In a store in south Washington where this preparation had
been used the stench of dead rats was very strong, showing a measure
of success.
DANYSZ BACILLUS.
Some three years ago the Biological Survey, assisted by the Bureau of
Animal Industry, tested the efficiency of Danysz virus. In the
laboratory from 10 to 50 per cent of rats fed on the virus died. In
the field, however, results obtained were unsatisfactory. Only 1 dead
rat was found from which the bacillus was recovered. Experiments with
field mice gave better results. All the mice fed in confinement died,
and field experiments resulted in many dead mice from which the
bacillus was recovered.
EXPERIMENTS DURING THE SAN FRANCISCO PLAGUE OUTBREAK.[AW]
Footnote AW:
These experiments were made by Passed Asst. Surg. G. W. McCoy,
United States Public Health and Marine-Hospital Service, in 1907–8
during the plague campaign in San Francisco and here published for
the first time.
Several proprietary biological products sold as rat exterminators were
made the subject of seven experiments on wild San Francisco rats, for
the purpose of ascertaining whether they were efficient for the
purpose for which they were sold. Seventy-six rats were used in these
experiments. About 10 per cent died within a month and there was
considerable doubt as to whether all of the deaths that occurred were
due to the agent used.
The following is a brief statement of the work done with these agents.
In each case the rats used were wild _Mus norvegicus_, caught in San
Francisco.
RATIN NO. 1.
Made by the Bakteriologik Laboratorium, Copenhagen, marked: “Effective
two months from April 28, 1908.” The preparation comes ready for use
in the form of a moist, mealy mass. On May 28, about 6 ounces of the
material was fed to 12 rats. They all remained well until thirty days
after feeding them when the experiment was regarded as terminated.
DANYSZ VIRUS.
The Danysz Virus Company (Limited), of London, furnished a preparation
in the form of a culture on a slant of solid medium, said to be
gelatine. The tube was marked: “To be used before June 1, 1908.” The
contents of the tube, mixed with bread, according to directions, was
fed to 6 rats. On the twenty-first day but 4 rats remained, 2 having
died and been devoured by their companions. The 4 that remained were
chloroformed, as the cage was needed for other purposes. Post-mortem
examination showed them to be entirely normal.
RATITE.
Furnished by the Pasteur Vaccine Company, Chicago. This preparation is
in the form of a culture in a liquid medium, presumably broth. The
bottle was dated April 10, 1908, and the label stated that it should
be used within twenty days from date of preparation. On April 29,
1908, 9 rats were fed with about 6 ounces of the preparation, mixed
according to directions. The rats all remained alive and well, and
when chloroformed on June 1, 1908, presented no abnormality on
post-mortem examination. In another experiment the contents of a
bottle of ratite was fed to 6 medium-sized _Mus norvegicus_. None of
the animals died from the effects of the agent, and when they were
killed on the fifty-fifth day after the feeding were found to present
no lesions.
The remaining work was done with rat virus, sometimes called
“Mouratus.” It is made by the same concern that makes the ratite. The
rat virus comes in the form of a culture on a solid medium. The
contents of three tubes was fed to 6 rats on May 26, 1908. Three of
these rats died within thirty days. Only one was secured for
examination before it had been mutilated beyond the possibility of
making a satisfactory examination. This rat had a large yellow liver
and a very large, dark, firm spleen. These appearances were probably
due to the agent used and it is not unlikely that these 3 rats died
from its effect. It will be observed that a very large dose was given.
On another occasion four tubes of Mouratus were used for feeding 6
_Mus norvegicus_. One of the rats died on the fifteenth day, showing
at autopsy an enlarged granular spleen and a granular liver. The other
rats were alive and well at the end of thirty-four days when the
experiment was discontinued.
Subcultures on broth were made from this preparation on three
occasions, always well within the time limit on the label. The
cultures were incubated in the dark, at room temperature, for forty
hours on each occasion. Liberal amounts of the subculture were fed to
a total of 31 rats. At the end of thirty days, it was found that only
2 of these rats had died. The others were alive and apparently well.
One objection to these agents which I have not seen stated is the
following: The lesions caused by at least some of these members of the
paracolon group may readily be mistaken for the lesions of plague, or
it will perhaps be more accurate to say they give rise to lesions that
create in one’s mind a suspicion of plague infection, and I have had
to put many a rat to the guinea-pig test in order to make certain that
a Danysz infection was not associated with the infection of plague, or
that a Danysz rat was not a plague rat. Of course, this is of no
consequence except in a community where antiplague measures are being
taken, and an observer of limited experience who did not put a rat to
a pretty rigid test would probably call some plague infected when in
reality such is not the case.
In addition to the data set forth in this report, I have on several
occasions fed the tissue of rats dead of Danysz infection to other
rats, but have never succeeded in reproducing the disease. In other
words, I have had no success whatever in raising the virulence by
passage through animals.
OPINIONS OF OTHERS.
Kitasato,[AX] 1906, states that the typhoid bacillus of the rat, which
has been effectively used for killing field mice, has been found
useless for house rats (_Mus rattus_) and therefore they no longer
employ it.
Footnote AX:
Kitasato, S.: Combating plague in Japan. Philippine Journ. Sci.,
vol. 1, 1906, p. 465.
Melvin,[AY] 1908, reports that recently several new rat viruses were
investigated in the Bureau of Animal Industry, with the result that
the experiments clearly demonstrated the ineffectiveness and
unreliability of the preparations tested.
Footnote AY:
Melvin, A. D.: Report of the Chief of the Bureau of Animal Industry
for 1908. Washington, 1908.
Räbiger and Schwinning,[AZ] 1906, tested the culture discovered by G.
Neumann and prepared by the joint stock company “Ratin” at Copenhagen
by applying it to rat destruction. Of house rats 90 per cent died;
black rats 42.9 per cent; while horses, dogs, goats, sheep, fowls, and
pigeons suffered no harm. Of seven experiments practically carried
out, six showed very good results; in one favorable results were
absent, which agrees with the experiments made in Denmark. There it
was likewise found that in individual locally limited places the rats
were able absolutely to withstand the infection of ratin.
Footnote AZ:
Räbiger and Schwinning: Versuche mit Ratin, einem neuen Ratten
tötenden Bacillus. Mitth. d. deutsch. Landw.-Gesellsch., 1906, No.
18. Rev. by Ehrenberg in Centblt. f. Bakt., 2. Abt., vol. 18, 1907,
p. 375.
Räbiger,[BA] 1905, states that experiments with Loeffler’s mouse
typhus bacillus and the bacillus of Danysz virus have been carried to
the conclusion that these bacterial preparations must be characterized
as practically worthless.
Footnote BA:
Räbiger, H.: Ueber Versuche zur Vertilgung der Ratten durch
Bakterien. Landw. Woch. f. d. Prov. Sach., 1905, p. 142. Rev. by
Stift in Centblt. f. Eakt., 2 Abt., vol. 15, 1905, p. 86.
In 1903 Neumann discovered in Denmark a rat-killing bacillus, which
has been placed on the market by a society under scientific control
under the name of “ratin.” Feeding experiments with this bacillus were
tried under conditions as nearly natural as possible upon white mice,
gray house mice, long-tailed field mice, and gray rats. The experiment
animals were fed with cubes of white bread impregnated with virulent
cultures. White mice show the least power of resistance, since they
die within six days; house mice died in six to nine days; the greater
part of the rats died from the sixth to the sixteenth day after
feeding; a small percentage lived. The long-tailed field mice, which
are shown to be insusceptible to Loeffler’s bacillus, also remained
perfectly healthy after repeated feedings with bread infected with
ratin.
Brooks,[BB] 1908, reports the results of tests made with azoa on rats
and mice, both in captivity and at large, but without any apparent
discomfort to the animals. One of the tests is described as follows:
Footnote BB:
Brooks, Fred E.: Notes on the habits of mice, moles, and shrews. A
preliminary report. Bull. 113, W. Va. Univ. Agric. Exper. Sta.,
Morgantown, W. Va., Jan., 1908.