CATTLE, WORMS AND ZOOPROPHYLAXIS

Epidemiological studies in North Cameroon indicate that a high populat ion density of cattle in relation to man protects from severe onchocer ciasis. In the following, we present a mathematical model which allows to study the effects of zoophily of the vectors, of concomitant immun ity in the human population and of cross-protective immunity caused by the infective larvae of a bovine parasite, Onchocerca ochengi, inocul ated into man by Simulium damnosum s.l. Besides this influence on onch ocerciasis, cattle also play a major role in the epidemiology of malar ic (zooprophylaxis through vector dilution) and schistosomiasis (prote ction by crossreactive concomitant immunity).