River Blindness Worm

The river blindness worm (Onchocerca volvulus) is a filarial nematode transmitted by blackflies that breed in fast-flowing rivers. It causes onchocerciasis, with intense itching, skin disease and in many cases blindness, mostly in Africa.

🧬 Field Guide Specimen: Open River Blindness Worm in the CRV Science Field Guide to log the specimen, see its place among the Ecdysozoa lineages in the Cladogram Explorer, and test your recall in the Red List conservation game.

Blackflies of the genus Simulium breed in fast-flowing rivers, which is why the disease is found near them. Larvae from the fly develop into adult worms in nodules under human skin, and the females release millions of microfilariae.

Microfilariae that move into the eye and die cause inflammation of the cornea and retina. Responses to the worm's Wolbachia bacteria contribute to disease. See Wolbachia.

The drug ivermectin kills microfilariae. Its maker, Merck, pledged in 1987 to donate it for as long as needed, and mass treatment has eliminated onchocerciasis in several countries. William Campbell and Satoshi Ōmura shared the 2015 Nobel Prize in Physiology or Medicine for ivermectin.

• Bancroft's Filarial Worm — another filarial worm
• Wolbachia — a symbiont of filarial worms