A review of Simulium damnosum s.l. and human onchocerciasis in Nigeria, with special reference to geographical distribution and the development of a Nigerian national control campaign

Abstract

The confirmed geographical distribution of human onchocerciasis and its Simulium damnosum complex vectors in Nigeria is reviewed with the aim of defining the endemic zones of the disease relevant to the planning of a Nigerian national onchocerciasis control campaign. Five major endemic zones are recognized, a terminology suggested for them, their sizes estimated and the disease and vector situation within each zone briefly described; four of the zones are in savanna areas of the north, and the fifth in forest-savanna mosaic and forest areas of the south-west. Other areas where disease and/or vectors have been reported are briefly considered. Maps are given of known vector breeding sites, of disease distribution, and of the approximate extent of the anticipated control zones. The scanty available data on cytospecies identity of the vectors, vector biting rates, and Onchocerca volvulus transmission potentials, are reviewed, and it is stressed that acquisition of distributional data for the individual members of the S. damnosum complex and of ATP data is essential for the planning of control. An historical resumé, accompanied by a comprehensive bibliography of the published literature, of the work to date in Nigeria is included.