Onchocerciasis is also known as river blindness. It is a parasitic disease of the skin and eyes caused by the filarial worm and it is transmitted by repeated bites of infected blackflies. These blackflies breed along fast-flowing rivers and streams, close to remote villages located near fertile land where people rely on agriculture.
In the human body, the adult worms produce embryonic larvae (microfilariae) that migrate to the skin, eyes and other organs, and they induce intense inflammatory responses when they die. Infected people may show symptoms such as severe itching and various skin changes. Some infected people develop eye lesions which can lead to visual impairment and permanent blindness. In most cases, nodules under the skin form around the adult worms.
For full information please see below WHO fact sheets: