Background on Onchocerciasis

Onchocerciasis is also known as river nile virus. It is caused by the parasitic worm Onchocerca volvulus (CDC 2013). The worms are closely related to roundworms. It transmitted by direct contact of a vector, this vector is a black fly. The black flies repeadily bites the host injecting the parasite. The disease is called river blindness because  the black flies live and breed near streams and river. and can result in blindness of the host. Not only does it cause blindness but it also causes an unbearable itch and nodules under the skin. It is considered to be a neglected tropical disease. The life cycle is shown below where it explains how it affects a human (CDC, 2013)

http://www.cdc.gov/parasites/onchocerciasis/biology.html