river blindness definition
Onchocerciasis, also known as river blindness and Robles disease, is a disease caused by infection with the parasitic worm Onchocerca volvulus. Symptoms include severe itching, bumps under the skin, and blindness. It is the second most common cause of blindness due to infection, after trachoma. The parasite worm is spread by the bites of a black fly of the Simulium type.