Economic Importance for Humans: Negative
Onchocerca volvulus is the pathogen responsible for the disease onchocerciasis, or river blindness. Infecting at least 17.7 million people worldwide, this non-fatal but severely debilitating disease is endemic in 37 countries (30 in Africa, 6 in the Americas, and Yemen). The pathology of onchocerciasis is based on host immune responses to the adult worm and the microfilariae, with the microfilariae being much more immunogenic. Little inflammation is caused by live microfilariae, but dead and degenerating microfilariae in the skin cause severe dermatitis, intense itching, skin depigmentation, skin thickening, skin discoloration, cracking of skin, and loss of skin elasticity. Quite often, microfilariae migrate to the eye, and their death causes intense inflammation. Over years this sclerosing (scarring) keratitis hardens the cornea and causes blindness. Worldwide, onchocerciasis impairs the vision of 500,000 people, and causes complete blindness in another 270,000. In some communities, the frequency of visual impairment is as high as 30%, and the frequency of blindness can be more than 10%. Additionally, elephantiasis may result (from microfilarial infestation of the lymphatic system), along with associated hernias. Furthermore, this disease results in decreased worker productivity, and the skin disfiguration can reduce marital prospects, reduce dowry size, and disrupt social relationships.
Negative Impacts: injures humans (causes disease in humans )