River blindness (Onchocerciasis), is a disease caused by infection with the parasitic worm Onchocerca volvulus.

What are the symptoms of Onchocerciasis?

Symptoms include severe itching, bumps under the skin, and blindness. Globally, it is the second-most common cause of blindness due to infection, after trachoma.

How does it spread?

The parasite worm is spread by the bites of a black fly of the Simulium type. Usually, many bites are required before infection occurs. The Simulium flies live near rivers, hence the common name of the disease.

In numbers
About 15.5 million people are infected with river blindness. Approximately 800,000 have some amount of loss of vision from the infection.

Most infections occur in sub-Saharan Africa, although cases have also been reported in Yemen and isolated areas of Central and South America. In 1915, the physician Rodolfo Robles first linked the worm to eye disease. It is listed by the World Health Organisation as a neglected tropical disease.