Pittsburg dispatch. [volume] (Pittsburg [Pa.]) 1880-1923, 1889-11-03

animals De ao0eo up, ana II their seat ana
gravity be next taken into account, the NOR
tality among persons bitten amounts to 10
to 20 per cent. In other words, more than
so out of 100 persons suffer no evil effects
from the bite. 1t is easy, therefore, to be
deceived as to the value of any preventive
remedy. For if we apply it to a small num-
Der Of persons it will seem TO have been sue
cessful in four cases out of five Is that not
more than sufficient to warrant quack,
whose advice is taken, to say that his rem
edv is infallible, and to cause men to blindly
share his belief7
The experimental method judges facts
more severely. That method teaches us
that if we are to believe in the efficacy of a
preventive remedy against rabies among
persons bitten by rabid animals, it would be
necessary, in the first place, to discover q
process enabling the experimenter to repro
duce rabies in an animal at will. A num-
Der of dogs having. then, been inoculated
with rabies according to that process, would
then have to be divided into two patches,
the remedy being applied to one batch, and
the disease being allowed to run its course
unopposed in the other until death followed.
1t would be easy to compare the course of
the disease in the two lots, and the action
of the remedy could thus be conclusively
demonstrated, provided rabies and death
| did not follow on the introduction of the
virus into animals treated BY the remedy.
We have tested in this way remedies which
are supposed TO be able to prevent the oc-
currence of rabies, and are said to be in
fallible by their owners, but we have never
obtained any satisfactory results.
INocULATING DOGS.
It is not so easy as zone might think at
first to inoculate a series of animals with
rabies successfully. We have already
| called attention to the fact that if dogs be
bitten by rabid animals the disease does not
appear in all of them. A direct subcutane-
Gus incubation of the saliva of q rabid dog
! is hardly more successful. The saliva con-
tains, together with the microbe of hydro
phobia, other microbes of different kinds
which may give rise to assesses and other
morbid complications, and thus prevent the
occurrence of rabies In short, only a few
years ago, experimenters would not have
known where to find the virus in pure
state, nor to use it in such way as to pro-
duce rabies, and nothing but rabies.
Luckily, these two difficulties were solved
at the same time by the following discovery:
If the autopsy of an animal dead of rabies
be made, and if small portion of the brain,
spinal cord, or, better perhaps, of the
thicker part of the cord which unites this
to the brain-a part which is called medulla
oblongata, or bulbous-be taken, and if
this portion of the central nervous system
be crushed in a sterilized fluid, with all
necessary antiseptic precautions, and if
small quantity of this fluid be nov intro
duced on the surface of the brain of
chloroformed animal (dog, rabbit or guinea
pig) by means of hypodermic needle, after
trephining, the animal thus inoeulated will
contract rabies to a certainty, and that in a
relatively short time; that is, a period not
exceeding Is davs or 8 weeks
Do you wish, then, to test any remedy
which is said to prevent the occurrence of
rabies? Take two dogs and inoculate both
of them with the virus In the manner which
has just been described. Now give that
remedy to one of the dogs before or after the
operation, as many times as you like, and
leave the other dog to take its chance. You
will then notice tnat rabies makes its ap-
pearance as easily in the first as in the sec
Ond animal. OF course we have not tested
in this way all the numerous remedies
praised by quacks, but we have tried some
which are said to have proved most sue
cessful without our meeting with the least
success.
Very different results are obtained if the
method which published before the Acad-
emie des Sciences de Paris on October 16,
1885,. be used. That method of vaccination
resembles in many of its characteristics the
method of prophylaxls against contagious
diseases. These methods are based on the |
inoculation of attenuated virus. The injec- |
tion OF such attenuated virus vaccinates
animals, and thus enables them to resist the |
attack OF the corresponding virus.
Every virus, or rather all virulent and |
infectious microbes, may be attenuated BY |
natural or artificial means. The virus of |
smallpox in man is represented in an atten- |
uated condition BY the cowpox virus of bo- |
vine animals. The latter has been produced |
at least SO I am inclined to think-by |
accidental and successive inoculations OF |
human smallpox virus on the udders of |
COWS, and its present state of virulence has /
at last become fixed" there. In the same
way the virus of rabies is greatly modified
by successive inoculations on monkeys or
rabbits.
EFFECTS OF INCUBATION.
Similarly again the fatal virus Of anthrax
is modified by the action of air and heat un-
til at last it is thus rendered harmless It
passes through intermediate stages, how
ever, in which it may still prove fatal to
animals. of small size, but harmless when
lnoculated into domestic animals, although
it vaccinates the latter against the attacks
of the primitive fatal virus. In the same
way the virus of rabies may be attenuated
to any wished-lor degree by the action of ar
and moderate heat; and may then, when in
oculated into animals, enable them to resist
the action of the primitive fatal virus. In
other words, one may produce in dog a
state in which it is impossible for that ami
NAL to contract rabies. Take dozen dogs.
vaccinate them in the manner which have
Just mentioned, and then inoculate them at
the surface of the brain with the pure virus
OF rabies. Then perform the same opera
tion, at the same time, on IL other nom
va ka1 - Al |
dozen will contract the disease, but the 12
other animals will all die of it after exhib-
iting all the various symptoms typical of
rabies, and it resembles in every particular
that produced by the bite of rabid animal
wandering about the streets. The expert
ments which 1 have just mentioned, and
which show that dogs may be vaccinated
against rabies, may be successfully repeated
on other dogs even if they have been bitten,
before the inoculatIons are begun by rabid
animals, provided too long period between
the time of the bite and that of the protec-
tive inoculations has not elapsed. The
success of such course of treatment de-
pends on the usually long period of time
between the day of the bite and
the time at which the first symptoms of
rabies show themselves. The immunity due
to vaccination is produced in animals before
the epoch at which the acute symptoms of
rabies ought to appear. This is indirectly
but fully proved by the fact that if the Pc
riod of incubation in dog be much short
ened our method may not prove successful
in vaccinating that animal. 1t the virus
be, for instance, inoculated at the surface of
the brain, the disease often follows as early
as two weeks after the incubation. It is
that in order to protect an animal
under these conditions, the whole
nrocess Of preventive inOculations mnst he |
carried on as quickly as possible if that an
imal is to be efficiently vaccinated before
the fatal symptoms of rabies appear on the