THE DURATION OF IMMUNITY IN CALVES INOCULATED
                     BY THE BULL VIRUS CUM SERUM METHOD
                                 AGAINST RINDERPEST

                                                      BY

                                       J. D'COSTA, G.B.V.C.,

                                 Temporary Deputy Director,

                                                   AND

                                 BALWANT SINGH, G.P.V.C.,

Offg. Head Laboratory Assistant, Imperial Veterinary Serum Institute, Izatnagar.

                    (Received for publication on 7th September 1932.)

      A survey of the available literature upon the subject of the immunisation of
calves against rinderpest indicates that the general opinion in most countries,
notably in Africa, is that calves do not form a suitable medium for the practice of
this method of immunisation, in that the duration of the immunity conferred as
compared with that developed in adult cattle is so uncertain as to be of negligiblt
value in the immunisation of cattle in extensive areas.

      The earliest available references on the subject to which we have access is that
of Montgomery [ 1915-16 ], who states that the double inoculation of calves under
six months old does not always result in the production of permanent immunity,
and Pool, India [ 1921 ], states that calves under 9 months old should not be
inoculated. P. Croveri, Somaliland [ 1919 ], Walker, Kenya [1921 ], and Askar
Mohammad Bey, Egypt [ 1924 ], have described experiments upon calves from
immune cows, which would indicate the presence in such calves of a partial or
complete immunity ; this immunity depending upon the ingestion of anti-bodies in
the milk from immune mothers. The immunity wanes as the animal becomes older
and completely disappears a short time after weaning. In the experiments of
Walker, Kenya [ 1929 ], and Deutressoulle, West Africa [ 1924 ] the immunity in
unweaned calves from immune cows was of such strength as to withstand without
fatal result a test inoculation of virulent blood alone. According to Walker [ 1921]

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