Annual report of the Veterinary Department, Sudan Government.

  • Sudan. Veterinary Department.
Date:
[1932]
Catalogue details

Licence: Public Domain Mark

Credit: Annual report of the Veterinary Department, Sudan Government. Source: Wellcome Collection.

    71/84 (page 36)
    oo Since some method had to be adopted as a standard for reference it was decided, (a) to adopt the intramuscular route, as being in one's own experience surgically less objectionable than either the sub¬ cutaneous or intraperitoneal, while producing a serum of at least equal potency, and (b) to take as the basic rate of hyperimmunisation the very highest that the cattle would tolerate, (any lower standard would be inconclusive). The two points for immediate consideration are therefore (a) whether some better route for hyperimmunisation than the intramuscular can be adopted, and (b) whether the rate of byperimmunisation can be reduced. In regard to route of injection, the intrarumenal process as employed in Tanganyika was studied during 1932* A group of twelve immune bulls was hyperimmunised and bled at exactly the same intervals as the routine serum producers, the only difference being that at each hyper- immunising injection the intrarumenal group received double the standard dose of virulent blood (merely because they could tolerate it). Five such injections were practised, at intervals of 25 days, and the mixed serum obtained from bleedings after each dose of virus was kept separate. Later, the five samples were tested on susceptible cattle at a dosage of 10 c.c. per 100 lb. body weight, together with some controls. The serum proved in all cases of low potency; there was no apparent difference in the five samples, all were equally poor. This observation in no way negatives the Tanganyika results; it is rather that in that Territory a serum of lower potency is efficacious. Reference to Annual Reports of the Veterinary Pathologist from 192if onwards shows that a very high recovery rate is constantly recorded among susceptible control cattle, and it seems quite probable that in such circumstances a serum of indifferent potency will protect local cattle sufficiently for practical purposes. In the Sudan, however, the intrarumenal process appears not to be very promising. Regarding the reduction of intensity of hyper¬ immunisation by the intramuscular route, two methods for study present themselves (a) To retain the maximum tolerated dose of virus but to increase the interval between injections, and (t>) to retain the standard interval but to decrease the dose of virus. Of these the former was roughly tried during 1932 using a group of IfO serum producers% Five hyperimmunisations Were practised at monthly intervals, with four weekly bleedings between injections. The serum from each bleeding was kept separate. Teste were finally carried out on nine mixed samples, viz : all Jth. day, ligth. day, 21st. day and 28th. day bleedings, and mixed samples of all bleedings after the 1st. , 2nd. , Jrd. , 4-th. , and 9th. hyperimmunisations. Three cattle only were used for each sample, and only a dosage of 10 c.c. per 100 lb. body weight was tested. Controls were of course included. The result was that the serum proved fairly good but not so good as any one of three routine samples titrated during the seaso