Onchocerciasis, more commonly known as river blindness, is a parasitic disease of the skin and eyes. It is caused by the bite of a black fly infected with onchocerca volvulus worms. Most cases are found in tropical areas in Sub-Saharan Africa, Yemen and in some countries in Latin America. Those who live near fast-flowing streams and rivers (the habitat of the black fly) are highly at risk, though usually repeated bites are needed to become infected. Once the parasitic worms have entered the body, they produce larvae which migrate to the skin, eyes and other organs. This migration induces symptoms such as severe itching, skin lesions, nodules and eye lesions. Additionally, the continuous severe itching can result in long-term damage to the skin, including changes in the colour of the skin (leopard appearance) and thinning of the skin (cigarette-paper). Larvae in the eye cause reversible lesions on the cornea, though without annually treatment it results in permanent clouding of the cornea and blindness. The leopard appearance and the potential to become blind are risk factors for stigmatization and social exclusion.
Recently, large-scale treatment strategies, such as the African Programme for Onchocerciasis (APOC; ended December 2015) and the Onchocerciasis Elimination Program of the Americas (OEPA), have resulted in interrupted transmission in 11 of 13 endemic areas in America, higher therapeutic coverage and the successful elimination of river blindness in Colombia (2013), Ecuador (2014), and Mexico (2015).
Click here for the latest WHO 'Weekly epidemiological record' on the progress of eliminating human onchocerciasis