onchocerciasis

onchocerciasis, filarial disease caused by the helminth Onchocerca volvulus, which is transmitted to humans by the bite of black flies in the genus Simulium. The disease is found chiefly in Brazil and Venezuela in the Americas and in sub-Saharan Africa, in a broad belt extending from Senegal on the west coast to Ethiopia on the east; in Africa its northern edge is about 15° N of the Equator, and it extends as far south as...