Onchocerciasis or ‘River Blindness’ is caused by infection from a parasitic worm, Onchocerca Volvulus, found along river valleys in Africa, Yemen and some Central American countries. The disease is transmitted by a small ‘black fly’. In addition to eye complications and blindness, Onchocerciasis causes a disfiguring skin rash.

Spraying of black fly breeding sites is one control method but is expensive. Annual treatment over several years of members of infected communities with the drug Ivermectin (Mectizan®) has proven to be successful in terms of both control and elimination of the disease in several countries.