Onchocerciasis in Imo State, Nigeria 1: The prevalence and distribution in the Middle Imo River Basin, Nigeria

Abstract

A survey of the prevalence and distribution of onchocerciasis was carried out in 21 rural communities in the Middle Imo
River Basin, Nigeria where no previous epidemiological data exist. Of the 4,037 persons examined between March 1997 and
December 2000 using the skin-snip method, 766 (19.0%) were infected with Onchocerca volvulus microfilariae (mf). The
prevalence and intensity of infection varied (p<0.05) between the communities and increased with age coinciding with the
period when most clinical signs manifest. Males had slightly higher infections (20.3%) than females (17.3%); farmers (29.8%)
and fishermen (23.9%) were more infected than other occupational groups. Classical and non classical manifestations were
associated more with subjects 30 years and above. Some non-classical manifestations namely epilepsy (r = 0.47; p<0.029)
and hernia (r = 0.49; p<0.026) were not however strongly correlated with mf prevalence. The Low Community Microfilarial
Load (CMFL) (11.7 mflss) indicates the efficacy of community self treatment with ivermectin which is on going in the area.

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Nigerian Journal of Parasitology Vol. 27 2006: pp. 16-22