Syn: river blindness. A chronic filarial worm infection transmitted by the bite of a blackfly, Simulium damnosum, that is prevalent in rivers and streams in parts of Sub-Saharan Africa. The worm was introduced to Central America in African slaves, and the condition occurs in tropical regions of Mexico and Guatemala. The worm causes fibrous nodules in dermal tissue that ulcerate, allowing female worms to discharge microfilariae; it often invades the eyeballs, where it destroys the vitreous and aqueous, causing irreversible blindness. An elimination program sponsored by the World Bank, FAO, WHO, and UNDP is based on environmental vector control and use of larvicides to block transmission of microfilariae. Facts about the condition are available at http://www.cdc.gov/ncidod/dpd/parasites/onchocerciasis/default.htm and at http://www.who.int/tdr/diseases/oncho/default.htm.
Subjects: Public Health and Epidemiology.