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Onchocerciasis - River Blindness

Infection with nematodes of the genus ONCHOCERCA. Characteristics include the presence of firm subcutaneous nodules filled with adult worms, PRURITUS, and ocular lesions. Source: DECS/BIREME


© PAHO/WHO

Onchocerciasis is a parasitic disease caused by the filarial nematode worm Onchocerca volvulus. It is transmitted to humans by black flies (genus Simulium) and can cause severe skin and eye disease, including blindness. The disease is commonly known as “river blindness” because the larvae of the blackfly vectors breed in fast flowing rivers. Onchocerciasis is endemic in Africa, and in 13 foci in six countries of the Americas (Brazil, Colombia, Mexico, Guatemala, Ecuador, and Venezuela), where it was introduced through the slave trade. The transmission has been interrupted or eliminated in 11 of 13 foci of the Americas. As a result of a regional initiative, only about 20,495 people are still in need of continual treatment in Brazil and Venezuela (Yanomami indigenous population). Furthermore, Colombia is the first country in the world to achieve the verification of Onchocerciasis elimination.

General information about this disease

Strategic Partners

[ Collaborating Centers Website ]

Regional Office for the Americas of the World Health Organization
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