An infection of the skin and eyes also known as river blindness and caused by a parasite called a filarial worm.

Onchocerciasis is caused by parasites spread by infected black flies. The illness also is called river blindness. In people, the parasite grows in the skin. Adult worms stay in connective tissue. Worms at other stages can be found in the blood, urine, lymph system and mucus from the respiratory system.

Symptoms of onchocerciasis may not appear for up to 1 to 2 years after infection. Skin sores, itching and bumps may develop. Eye lesions can lead to vision changes and blindness.

Onchocerciasis is treated with medicine called an anti-parasitic, which targets the worms that travel in body fluids.