13
for the process could be repeated a third time, or larger quantities taken the
second time if thought advisable, and at the same time the slaughter of the
animal if avoided. This method has considerably reduced our difficulties in
preparing large quantities of serum, and at the same time has lessened consider-
ably the number of animals which it has been necessary to inoculate with the
disease for the purpose of obtaining virulent blood.
26. Testing the strength of the Serum.—As before the serum can be used in
outbreaks, its strength has to be tested on a series of animals in order to find out
exactly what dose per given body-weight must be used together with a small dose
of virulent blood injected into a different part of the body, in order to produce
a mild attack of rinderpest, with subsequent immunity for life; 18,000 c.c. of
serum were recently mixed together and tested in this way on eight Hill cattle
and four Plains ones in four series, each series receiving a different dose in propor-
tion to their weights, and the remarkable result was obtained that, although all
the Plains cattle, including the one which had the smallest dose, namely, 15 c.c.
per 600 lb weight, remained without any marked symptoms of the disease,
although two of them had distinct temperature reactions, yet all the Hill animals
developed the disease and all but one died of it. A similar result was obtained
when the six animals were salted for subsequently obtaining serums as
mentioned above, for all the Plains animals had but little reaction, while
two Hill cattle which were inoculated in the same way died of the disease,
although weight for weight they had received a rather larger dose of the
protective serum than the Plains ones. Other Hill cattle have since been tested
with larger doses of the serum, and successfully passed through a mild attack
of the disease, 45 c.c. per 600 lb being the dose required for the purpose.
It appears, then, that there is a very great difference in the susceptibility
of Hill and Plains animals, and this fact raises the important question as to
whether there may not be a considerable difference in the liability of
different breeds of Plains cattle in different parts of India, and renders it neces-
sary to carry out the simultaneous method of inoculation in several outbreaks
with great caution before coming to a final conclusion as to the value and prac-
ticability of this method in India. With further experience it is expected that
a still more powerful serum than the above will be made here.
27. Inoculation in affected villages.—A visit was paid to some affected
villages in Bareilly during the end of April and the beginning of May in order
to carry out this method, and although the disease in most of the villages was
found to be on the decline on account of the recent rapid increase in the tem¬
perature, yet one village was found in which, out of 145 animals, 73 had been
attacked and 24 had died. Here the villagers readily assented to inoculation
of the healthy cattle and allowed me to take some blood from one of the
diseased animals for the purpose. Twenty-four animals were inoculated in
this village in the course of a morning's work, the dose of serum used was
30 c.c. per 600 lb weight, being twice that which had proved sufficient in the
case of Plains cattle at Muktesar, so as to be on the safe side, and not to run
any risk in case the animals were more susceptible than the Muktesar ones of
developing a severe attack of the disease. I revisited this village six days later
and found that none of the inoculated animals had developed any very marked
symptoms of the disease, which were evident to the villagers, while out of 39
uninoculated, 9 had become affected and 2 had died. On closely examining the
inoculated animals 8 of them were found to have very slight symptoms of the
disease, and will probably be protected for a long time, while the rest
should (in accordance with South African experience, which has not yet been
confirmed in India, but which is being tested at Muktesar), be rendered insus-
ceptible for several months at least. One of the Veterinary Assistants visited
this village again two weeks after the inoculations were carried out, and found
that all the inoculated animals were still free from the disease, but one more of
the uninoculated had died of rinderpest and the disease had very nearly died out.
As from inquiries in these villages it appears that any individual one is rarely
attacked oftener than once in twenty years, this degree of immunity should be
sufficient to carry them over the present outbreak, and these cattle are not
likely to be attacked again with the disease within their life-time, which is all
that is necessary.