In a bovine model of onchocerciasis, protective immunity exists naturally, is absent in drug-cured hosts, and is induced by vaccination.

Onchocerciasis (river blindness) is a major parasitic disease of humans in sub-Saharan Africa caused by the microfilarial stage of the nematode Onchocerca volvulus. Using Onchocerca ochengi, a closely related species which infects cattle and is transmitted by the same black fly vector (Simulium damnosum sensu lato) as O. volvulus, we have conducted longitudinal studies after either natural field exposure or experimental infection to determine whether, and under what circumstances, protective immunity exists in onchocerciasis.

Repeated high doses of avermectins cause prolonged sterilisation, but do not kill, Onchocerca ochengi adult worms in African cattle.

Background: Ivermectin (Mectizan, Merck and CO. Inc.) is being widely used in the control of human onchocerciasis (Onchoverca volvulus) because of its potent effect on microfilariae.