Towards the elimination of onchocerciasis.

Human onchocerciasis is a severely disabling filarial disease that is endemic in 28 African countries, six Latin American countries and Yemen. The disease causes a high burden of blindness and visual loss, along with itching and other severe dermal manifestations. It constitutes a significant obstacle to socio-economic development in highly endemic riverine areas, where the Simulium blackflies that act as vectors breed. Onchocerciasis has been subject to control efforts for more than 50 years, initially mainly through vector control but since 1988, with free access to ivermectin (Mectizan), also through large-scale chemotherapy. The Onchocerciasis Control Programme in West Africa operated successfully from 1974 to 2002 in 11 countries, covering the worst savannah foci of the disease through vector control and, in its later stages, also through ivermectin distribution. The African Programme for Onchocerciasis Control was established in 1995, to cover the remaining endemic areas in Africa, with the sustainable annual distribution of ivermectin by 2010 its main goal. Meanwhile, the Onchocerciasis Elimination Program for the Americas is making rapid progress in the virtual regional elimination of the disease through ivermectin distribution, which is achievable primarily because the vectors in the western hemisphere are less efficient than those elsewhere. The global elimination of onchocerciasis as a public-health problem is now within reach but this will require long-term strategies to secure the great gains made so far, through ivermectin treatment and local vector control. Research is needed to define the optimal approaches with the existing tools and to intensify the development of alternative strategies, such as macrofilaricidal drugs for wide-scale use.