river blindness

For more information on river blindness, visit Britannica.com.

A disease occurring in tropical Africa and Central America, transmitted by black flies and caused by infestation with filariform nematodes of the genus Onchocerca, especially O. volvulus, and characterized by nodular swellings on the skin and lesions of the eyes. Also called river blindness, volvulosis.

The diseases caused by infection with the nematodes Onchocerca spp. The presence of large numbers of microfilariae in the skin is associated with a severe, summer dermatitis called also wahi, kasen in cattle and summer mange or allergic dermatitis in horses. See also sweet itch.
An association is suspected between periodic ophthalmia in horses and onchocerciasis because of the finding of microfilariae in the eye and because Onchocerca volvulus is a known cause of blindness in humans.
The adult worms cause little problem to the animals but the hides and carcasses are damaged and reduced in value. The relationship between the worms and the occurrence of fistulous withers, poll evil and tendonitis is unproven. The lesions in the aorta caused by O. armillata are often extensive but appear to cause little clinical disease.

The noun has one meaning:

Meaning #1: infestation with slender threadlike roundworms (filaria) deposited under the skin by the bite of black fleas; when the eyes are involved it can result in blindness; common in Africa and tropical America
  Synonym: onchocerciasis