36
REPORT OF THE IMPERIAL INSTITUTE OF VETERINARY RESEARCH,
From the above curves it would seem that single injections of the " 9-salt " solution
had a distinct stimulating effect upon antibody " secretion " while antibody secretion
was active in the animal body, but that it had little effect later when the animal tissues
themselves had relaxed their activities in this respect. From the results depicted for Lot
I it would also appear that specific so-called " hyperimmunization " (with virulent blood)
had uncertain effects at this later stage.
Work upon the above lines has been prosecuted subsequently, throughout the year
under report, and an attempt has been made to introduce the system of salt injection
into routine practice. However, it is felt that it is still difficult to express a decided
opinion upon the relative merits of the " brews " produced with and without salt, and
it is beyond the compass of this brief Report to enter into discussion of the results as they
stand. It is hoped that further definite knowledge on this subject will be forthcoming
at the time when the next Report is prepared.
(II) Possibility of fly transmission of rinderpest. The work further executed by Mr.
S. K. Sen, Assistant to the Imperial Entomologist, was as follows :—
A series of experiments was carried out with a view to testing the possibility of the
mechanical transmission of rinderpest through the agency of Musca domestica.
Three kinds of infective material were used, viz., virulent blood, nasal discharge and
fresh fæces, the materials being obtained from experimentally infected animals at the
height of the disease.
The preliminary series of experiments were directed with the object of ascertaining
whether the virus remained viable in the body of the fly. Flies fed on infective materials
were crushed and inserted into pockets prepared beneath the skin of susceptible bulls,
or saline suspensions of crushed infected flies were inoculated intravenously into the ani-
mals, the interval between the infective feed and the inoculation varying from 3 to 52
hours. Of the 23 bulls thus treated eleven developed rinderpest, the animals in these
cases being inoculated with the bodies of flies injected at intervals of 3, 6, 12 and 24
hours from the time of the infective feed.
The subsequent series of experiments were designed with reference to the natural
conditions under which the disease was thought likely to be transmitted through the
agency of this fly. At intervals varying from 2 minutes to 4 hours from the time of the
infective feed, living infected flies were brought in contact with wounds, nasal mucous
membrane and conjunctiva of susceptible bulls, or infected flies or their fæces adminis-
tered orally the animals. The results obtained were of a completely negative order,
indicating that M. domestica did not act as an intermediary in the natural transmission of
rinderpest.
The possibility of the common cattle-louse, Linognathus vituli, acting as vector
of rinderpest was suggested by the existence of an immunological similarity of the
disease to human typhus, the exciting agent of which is known to be transmitted by
Pediculus humanus. The infectivity of saline suspensions of crushed infected lice was
tested upon three bulls and of these one developed rinderpest. The results of trans-
plantation of infected lice on a healthy bull were negative.
The full report upon these experiments has now been submitted for publication.
(III) The resuscitation of intestinal coccidiosis brought about by rinderpest affection.
An extensive series of examinations of fæces from animals artificially infected with
rinderpest was undertaken by Mr. Cooper, using one of the newer, floatation methods
(SHEATHER'S) for ascertaining the degree of infection with oocysts. It is sufficient to re-
produce here the following " composite " Chart X of 10 hill bulls passing through a
relatively mild type of infection to indicate the relationship between the two conditions.
A further reference to this subject will be made in the summary relating to coccidiosis.
(b) Hæmorrhagic septicæmia. The outcome of a series of systematic investigations
prosecuted for a period of two years to determine the optimum methods of anti-serum pre-
paration has been stated in the section of this Report dealing with serum production.
Contrary to what was believed at the time of writing the last Report, simultaneous in-
oculation of anti-serum and living antigen of much degraded virulence proved to confer
a very solid immunity, comparable with that produced subsequent to the inoculation of
highly virulent antigen, when the resistance of the immunized animals was tested after-
wards with exalted virus ; the resistance developed after repeated inoculations with dead
virus broke down when tested in the same manner.