Observations on cattle schistosomiasis in the Sudan, a study in comparative medicine. II. Experimental demonstration of naturally acquired resistance to Schistosoma bovis
Bushara, H.O.; Majid, A.A.; Saad, A.M.; Hussein, M.F.; Taylor, M.G.; Dargie, J.D.; Marshall, T.F.; Nelson, G.S.
American Journal of Tropical Medicine and Hygiene 29(3): 442-451
1980
ISSN/ISBN: 0002-9637 PMID: 7386722 Document Number: 162796
Observations on S. bovis in cattle at Kosti, Sudan, showed a significant fall in age-specific prevalence and intensity with age, based on faecal egg counts. To test the possibility that this is due to acquired resistance, Kosti cattle and a control group of cattle of similar breed and age from an uninfected area were experimentally challenged with 70 000 S. bovis cercariae. Clinical observations showed very clearly that the Kosti cattle were able to withstand almost completely the effects of the challenge, whereas the controls developed lethal infections. Resistance was further demonstrated by clear differences between the two groups in terms of their body weights, haematological measurements, histopathological and pathophysiological responses, and worm egg counts. The data suggested that the main basis of the resistance was a suppression of egg production by the worms from the challenge, rather than absolute prevention of their maturation. There was also evidence of a suppression of the fecundity of worms in the naturally infected Kosti cattle.