NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
4
number and small in size. In the dog of the 6th passage they could not be
found nor were they demonstrable in any of the succeeding animals, although
careful search was made in every instance through well stained specimens.
It would appear, therefore, that the same thing happens when the virus of
the street is passed through dogs as occurs when it is passed through rabbits.
We have searched for Negri bodies, but without success, in the central nervous
system of the passage fixed virus rabbits. Further, Schiffmann has found that
by passing the virus of the street through rabbits, Negri bodies soon disappear.
He looks upon this disappearance as a means of deciding whether one is dealing
with a definitely fixed virus, or not.
SUMMARY.
A virus originally obtained from a dog in the street was passed through a
series of 13 dogs, by subdural inoculation or by intraocular injection. An
increase of virulence resulted. The virulence of the virus was also increased for
the rabbit.
Negri bodies were demonstrable in certain cells of the central nervous
system of the dogs of the first few passages, but not in the same cells of the
animals of the later passages.
III.— A peculiar form of rabies seen in rabbits and dogs.
During the last few years in the course of the routine work of the Institute
it has frequently been observed that a rabbit, which had received a subdural
inoculation of street virus remained in good health for a time. It then gradually
became emaciated and died without developing any of the symptoms of rabies
which are usually seen in the rabbit, namely, paralysis, tremor, etc. In most
instances the emaciation was of slow progress, the disease lasting a month or
more. In other cases, however, the wasting was observed to begin very
soon after the infection and to run a very rapid course, so that death took
place within 10 days of the inoculation. At first these rabbits were not
considered to be suffering from rabies. It was thought that the symptoms
might be due to the toxicity of the foreign nerve material which had been
introduced. On further investigation, however, it was found that rabbits in-
jected subdurally with emulsions of the medulla of these emaciated animals
developed typical rabies. It was also found that in some instances, before the
usual symptoms of rabies appeared, two or more passages had to be made, the
rabbit of the first passage developing symptoms similar to those seen in the ori-
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ginal animal, that is to say, becoming emaciated and dying without showing any
tremor or paralysis. In Protocol II several examples of this type of rabies have
been set forth.
The first two observations (Table 2) relate to rabbits which had received sub-
cutaneously a dose of fixed rabbit virus.
In the first example (a) slow progressive emaciation was observed followed
by death 58 days after the inoculation. The passage rabbit from this animal
also became gradually thinner without developing paralysis, and died 27 days
after infection. The disease, therefore, had run a more rapid course than was
the case with the first animal. The second passage rabbit showed typical
symptoms of rabies,—tremor, paralysis, etc., on the 20th day and died on the
21st day. It did not become emaciated. In the second example (b) the emacia-
tion began soon after the inoculation and ran a fairly rapid course, death taking
place in 22 days. The passage animal showed marked paralysis and tremor
on the 7th day.
In a second group of observations, examples of which are given in Table 3,
the inoculations were made subdurally with emulsions of the brain of dogs which
had died of suspected rabies, that is to say, with the virus of the street. In
each instance the pieces of brain had been in glycerine for a few days. Three
cases are recorded in the protocols. In one case the rabbit lived 57 days and in
another 17 days. The third case is remarkable, inasmuch as the emacia-
tion began immediately after the infection and ran a very rapid course, death
taking place 9 days after the subdural inoculation. The passage rabbit from
each of these original animals showed definite and typical symptoms of rabies
between the 11th and 13th days.
In the examples of this disease to which we have drawn attention above,
it is seen that death has always resulted. In some instances, however, a similar
condition has been observed, but the animals have ultimately recovered.
They have undergone progressive emaciation and become very weak, exactly
as we have already described. But instead of death taking place, the animal
after a time has gradually picked up and ultimately completely recovered. We
may cite the following cases—
On the 11th November, 1907, a rabbit was inoculated subcutaneously with
0.01 gramme of fixed rabbit virus. A month afterwards it was observed to be
wasting, and by the end of December it was noted to have become much
emaciated and very weak. After a time it began to recover and by July 1908
it was found to be fat and sleek.
A second example is that of a rabbit inoculated subdurally with an emulsion
of the medulla of a rabbit which had died very emaciated about two months after
the subcutaneous inoculation of fixed virus. This animal infected on the 29th
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January, 1908, was noted by the middle of March to be very thin and weak. It
then gradually got better and by July was plump and well.
It is impossible to say whether these were true infections of rabies or not..
Neither of the above two rabbits was immune to a subsequent subdural infection
of fixed rabbit virus. They were inoculated subdurally each receiving 0.2 c.c. of
a thick emulsion of fixed rabbit virus. They developed hydrophobia after an
incubation period each of 7 days and died on the 12th day.
Finally, the question arises if this form of rabies, characterised chiefly by
progressive emaciation, occurs in nature amongst dogs or other animals. We
have had reported to us several cases of sickness in dogs, in which the symptoms
closely resembled those described above in rabbits. In some of these cases the
experimental proof of rabies was obtained after the death of the animal, but only
one dog which might be said to have suffered from the type of disease we are
now considering, has come under our personal observation. Its history was as
follows—
It was bitten on or about the 12th February, 1908, by a dog which was
experimentally proved to be rabid. There were two wounds on the face: these
were cauterised. About the 7th March—that is to say, from 3 to 4 weeks after
being bitten, the animal was noticed to be ill and to have become thinner. The
emaciation progressed and on the 1st April was well marked. No paralysis was
noticed on this date. On the 3rd of April the animal refused food for the first
time. Next day it howled incessantly and the jaw was then noticed to have
dropped. It died on the 5th April. Negri bodies, numerous but of small size,
were demonstrable in the cells of the hippocampus major. A rabbit inoculated
subdurally with an emulsion of the medulla developed marked paresis by the
12th day and died on the 13th day.
SUMMARY.
Several cases of a form of rabies in the rabbit, in which progressive emacia-
tion is the chief symptom, are described. This type has been observed to
follow both subcutaneous inoculation of fixed rabbit virus and subdural injection of
street virus.
The disease generally runs a more or less chronic course but may be
comparatively rapid. The fact that this condition is true rabies has been experi-
mentally demonstrated. On sub-passage from animals dead of this form of the
disease typical symptoms of rabies in the rabbit have developed.
Rabbits showing symptoms of progressive emaciation after injection of
rabies virus have been observed to recover completely.
Finally this type of the disease has been observed in a dog infected in
nature.
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IV.—The susceptibility of various animals towards fixed rabbit virus.
It has long been known that, although it is easy to infect animals with rabies
by subdural, intraocular or even intramuscular inoculation of fixed rabbit virus,
certain species display a marked degree of insusceptibility to the subcutaneous
injection of even large quantities of this virus.
Most observers have experienced considerable difficulty in infecting dogs
by the subcutaneous inoculation of either fixed or street virus. Thus Bardach
(1888) was able to infect only 1 out of 22 dogs and Helman (1889) obtained
similar results. The latter also failed to infect monkeys by subcutaneous
injections of fixed virus.
Most workers have found that rabbits were more easily infected by the sub
-cutaneous channel than dogs.
Finally, it is generally believed that fixed rabbit virus is harmless to man
when injected subcutaneously and in this belief Nitsch (1905) injected himself
with 3 c.c. of an emulsion of the fresh cord of a passage rabbit.
We may now ask ourselves the question upon what factor does this com-
parative immunity of some animals to subcutaneous inoculation depend. Helman
(1889) believes that rabies virus produces infection only when introduced directly
into nervous tissues. It might also be suggested, as Nitsch evidently believes,
that the passage of the virus through the rabbit may so modify it as to render it
incapable of infecting certain other species, such as man, monkey, etc., when
injected subcutaneously, that, in short, there is some fundamental difference
between the virus of the dog and the virus of the rabbit—a difference similar to
that which is found in the modification, as regards its infectivity for man, which
small-pox virus undergoes when passed through the calf.
Although we have not been able to obtain a definite answer to this question,
we have several series of observations to record which bear upon it. These
observations consist, (1) of experiments made with the view of testing the
susceptibility of three different species of mammals to the subcutaneous in-
oculation of fixed rabbit virus; (2) of experiments made with the view of
comparing in a single species, namely, the guinea pig, and by subcutaneous
inoculation, the infectivity of fixed rabbit virus with that of a dog virus, and (3)
of observations on the susceptibility of monkeys to fixed rabbit virus inoculated
by different channels.
A.—SUSCEPTIBILITY OF GUINEA PIGS, RABBITS AND MONKEYS TO
SUBCUTANEOUS INOCULATION OF FIXED RABBIT VIRUS.
For these experiments a portion of the central nervous system of one of the
ordinary passage rabbits was used. The passage was between the 225th and
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23oth from the dog, the incubation period in a rabbit after injection subdurally
being, as a rule, six days, death taking place on the l0th day.
From a portion of the central nervous system of the rabbit an emulsion of
definite strength was prepared and from this emulsion various dilutions were
made as required. The amount of emulsion injected was always made up to
5 c. c. Great care was taken that the muscles were not penetrated and that the
injections were really made into the subcutaneous tissues.
The results of these experiments are set forth in Tables 4, 5 and 6 of the-
protocols.
Table 4 refers to guinea pigs, which, it will be seen, readily develop rabies
even when a very small quantity of virus is injected. With large amounts of
virus, however, the incubation period is on an average somewhat shorter than
with small quantities.
Table 5 refers to rabbits, which received the same amounts of virus as were
used in the case of the guinea-pig experiments.
It is first to be noted that rabbits can be infected fairly easily by subcutane-
ous injection of this virus, 14 out of 18 in the present series developing the
disease. Secondly, they would appear to be as susceptible to small amounts of
virus as to large quantities when the inoculations are made under the skin.
Thirdly, it is interesting to observe that the disease which follows subcutaneous
injection into rabbits is, as a rule, a more or less chronic one, without any of the
usual symptoms of rabies. In some instances, e.g., Rabbits 1, 10, 11 and
18, the animals showed tremor and paresis at the end of a definite incubation
period, but, as a rule, the onset of the disease could not be determined and death,
preceded by progressive emaciation, followed a considerable time after the
infection. We have already referred to this type of the disease and have
endeavoured to show that it is true rabies. Finally, a study of the table will show
that it cannot be said that the duration of the disease was at all proportional to
the amount of virus injected.
The last series of experiments refers to monkeys.
In Table 6 are put down the details relating to three monkeys which were
injected subcutaneously, each with a considerable quantity of fixed rabbit virus.
Two of these animals died of rabies, one after 48 days and the other after 76
days, that is to say, in each instance after a prolonged period of latency.
It is interesting to note, vide Table 6, that although these monkeys were
injected with fixed virus which gave an incubation period of 6 days when injected
subdurally into rabbits, two rabbits inoculated subdurally with thick emulsions
of the medullas of the monkeys did not develop the disease till after i8
and 31 days respectively. Both these rabbits showed symptoms typical of
rabies. Therefore, by a single passage through the monkey, infected subcu-
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taneously, the incubation period of the fixed rabbit virus had been greatly pro-
longed for the rabbit. This observation is of importance in connection with the
finding that the virus taken from the central nervous system of men who have died
of rabies in spite of anti-rabic treatment has nearly always given on subdural
inoculation into rabbits an incubation period considerably longer than that of the
fixed rabbit virus. On this evidence it has been concluded that the virus which
has caused the death of these persons is the dog virus of the street, inoculated at
the time of the bite, and not the fixed rabbit virus used for the preparation of the
vaccine. Our present observations in the monkey show that this method of
argument is not justifiable.
B.—COMPARISON OF THE SUSCEPTIBILITY OF GUINEA-PIGS TO FIXED
RABBIT VIRUS AND TO VIRULENT DOG VIRUS, BOTH BEING INJECTED
SUBCUTANEOUSLY.
As the guinea-pig is the most susceptible animal to subcutaneous injection
of a virus which has become fixed by passage through the rabbit, the guinea-pig
was now used to see if there was any difference in this respect between this
virus and a virus obtained from a dog and virulent for that animal, which had
never been passed through the rabbit.
The data which refer to the susceptibility of guinea-pigs towards fixed rabbit
virus have already been put forward in Table 4. Similar data concerning the dog
virus are set forth in Table 9. The virus was originally obtained from an animal
which had died of furious rabies in Meerut; after having been kept in glycerine
for several days it gave an incubation period of eleven days when inoculated sub-
durally into a rabbit. The virus was first passed through two dogs by subdural
inoculation. Both dogs died of furious rabies, the first after twelve days and the
second after ten days. The medulla of the second dog was now used to prepare
the emulsion for inoculation into guinea-pigs, the same technique being employ-
ed as has already been described in connection with the inoculation of rabbit
fixed virus into guinea-pigs. From a comparison of the two tables, namely, Nos.
4 and 9, we can only conclude that the guinea-pig is as susceptible to fixed
rabbit virus as to a virulent dog virus when the inoculations are made subcuta-
neously. It would appear, therefore, that passage through the rabbit does not
modify to any appreciable degree in the virus as far as its power of infecting
guinea-pigs is concerned.
C.—SUSCEPTIBILITY OF MONKEYS TO FIXED RABBIT VIRUS.
We have already seen that it is possible to infect monkeys with fixed
rabbit virus when injected subcutaneously in comparatively large quantity. We
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have now to add to this observation two other series of experiments which have
reference to the susceptibility of monkeys towards fixed rabbit virus.
In one series (Table 7) three monkeys were inoculated intraperitoneally with
0.5 gramme of fixed virus. Two of these animals developed rabies with a
comparatively short incubation period, namely, 15 and 16 days respectively. In
the other series (Table 8) three monkeys were inoculated subdurally with 0.003
gramme (0.3 cc. of a 1 per cent. emulsion) of fixed rabbit virus, which gave in
the rabbit after subdural inoculation an incubation period of 6 days. It is seen
from the table that all these three monkeys developed rabies, with incubation
periods of 8 and 9 and 10 days respectively.
It would appear, then, that monkeys are susceptible by all ordinary channels
to a virus which is separated from the dog by many passages through the rabbit.
Dog virus does not, therefore, become modified as regards its infectivity for
monkeys, by passage through the rabbit, as tested by these methods.
We have already seen, that there are certain facts which suggest that the
virus obtained by passage through the rabbit is, at least qualitatively, the same
thing as the virus of the dog. We have now brought forward further facts which
favour this view. It is necessary, therefore, before quitting this part of our sub-
ject, to bring together the evidence which supports this hypothesis. It is stated
as follows
—
1. By passage of the ordinary street virus through the dog, subdural
or intraocular methods being employed, its virulence for the dog is increased. At
the same time its virulence for the rabbit is exalted, so that it ultimately produces
the disease in rabbits after the same incubation period as does fixed rabbit virus.
It is to be remembered that dogs are quite as susceptible as rabbits to
the subdural inoculation of fixed rabbit virus.
2. Negri bodies are found in the central nervous system of practically every
dog which dies of rabies in nature. On passage of this virus through the dog by
subdural or intraocular injection, these bodies after a few passages can no longer
be demonstrated. The same phenomenon has been observed in passing street
virus through the rabbit by subdural inoculation.
3. No difference is observed between fixed rabbit virus and fixed dog virus,
as tested by subcutaneous inoculation into guinea-pigs.
4. Monkeys have been shown to be susceptible to fixed rabbit virus when
injected subdurally, intraperitoneally or subcutaneously.
If, then, the rabbit virus has the same properties as the dog virus and has
not become qualitatively modified by passing through the former animal, we are
almost forced to accept Helman's hypothesis on the problem of the relative
insusceptibility of certain animals to subcutaneous inoculation : that it must be
a question of the site where, and the manner in which, the virus is deposited in
II
the subcutaneous tissues. In connection with this hypothesis attention may be
drawn to the fact that fine emulsions of the medulla containing fixed virus,
especially if dilute, may very soon completely lose their infective power when
kept at 37 0 C. (vide Table 12).I t w o u l d a p p e a r a s i f s e p a r a t i o n f r o m l i v i n g
nervous tissue was sufficient to bring about the rapid death of the virus when kept
at body temperature.
,
SUMMARY.
1. It has been shown that it is comparatively easy to infect guinea-pigs by
the subcutaneous injection of fixed rabbit virus even in small quantity. They are
equally susceptible to subcutaneous inoculation of virulent dog virus.
2. Rabbits also are susceptible to injections of fixed rabbit virus under the
skin. The disease which results is often of a more or less chronic nature, mainly
characterised by progressive emaciation without any definite paralysis.
3. Monkeys also can be infected by subcutaneous injection of fixed rabbit
virus. The incubation period is much prolonged in these cases. It was found
that passage through a single monkey may greatly prolong the incubation period
of fixed rabbit virus for rabbits.
Monkeys are also susceptible to the subdural and intraperitoneal injection of
fixed rabbit virus. The incubation period after subdural infection is only slightly
longer than in the case of the rabbit similarly infected.
4. Certain observations are put forward which point to the conclusion that a
virus fixed by passage through the rabbit has the same properties and is identical
in character with street virus, exalted in virulence by passage through the dog.
•
V.—An attempt to immunise monkeys by means of single doses of
fixed rabbit virus injected subcutaneously.
An attempt was made in two series of experiments to immunise monkeys by
means of a single dose of fixed rabbit virus given subcutaneously. As we have
already shown that these animals may develop rabies after the injection under the
skin of a large quantity of this virus, the incubation period, however, being greatly
prolonged, it was hardly to be expected that any immunity would result. Our
results show this to be the case.
In the first series of observations (Table 10 )) six monkeys each received a
considerable amount, namely, 0.5 gramme of fixed rabbit virus.
Twenty-three days after this injection each monkey along with two untreated
controls received a subdural inoculation of a small amount of fixed rabbit virus.
As will be seen from the table all the monkeys died of rabies, and no appreciable
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12
difference in the incubation periods between the treated and untreated animals
could be made out.
In the second series of observations (Table II) six monkeys each received
subcutaneously a different amount of fixed rabbit virus, varying from 0.5 to
0.0015 gramme. Twenty-three days after this inoculation each animal, as well
as an untreated control, was injected subdurally with a small amount of fixed
rabbit virus. As a result all the monkeys died of rabies and again there was
no indication of any one of them having developed even a slight degree of
immunity.
SUMMARY.
In the hope that it might be possible to curtail the lengthy course of
treatment now in use, attempts were made to immunise monkeys by means of
a single injection of fixed rabbit virus under the skin. In one series of experi-
ments the amount of virus injected was varied. The animals were tested
twenty-three days after the inoculation by giving subdurally a small amount of
fixed rabbit virus. All the monkeys died of rabies and it would seem that no
degree of immunity had developed.
VI—Bactericidal properties of the serum of patients taken both
during the course of anti=rabic inoculations and after the
treatment had been completed.
Several workers—Babes and Cerchez (1891), Babes and Talasescu (1894),
Marie (1904-1907), Remlinger 1906-1907), Semple (1908)—have been able to
obtain from animals immunised with rabies virus a serum which, they state,
destroyed the virus when kept in contact with it "in vitro." Sera of highly
immunised animals have been used experimentally with the object of ascertaining
if they had any hindering effect on the evolution of the disease when injected
either before or after inoculation with the virus. Finally, attempts have been
made to immunise animals with a mixture of an immune serum and rabies virus.
In the present communication we do not intend to enter into these
questions, but to confine ourselves to the consideration of a number of
observations made with the object of finding whether bactericidal properties could
be demonstrated in the blood of patients either during anti-rabic treatment or
shortly after completion of treatment. In this connection it is to be noted
that Kraus and Kreissl (1902) have made some experiments which go to show
that anti-bodies towards the rabies virus only appear in the blood of those
subjected to anti-rabic inoculations 20 to 22 days after the treatment had
ended. On the other hand, Semple (1908) has put forward evidence which in