Onchocerciasis in Plateau State of Nigeria. II. The prevalence among residents around the Assob River area.

A study of the prevalence of human onchocerciasis in eight villages around the Assob River in Jos Plateau, Nigeria, was undertaken between October 1983 and March 1985 using the skin-snip method. A total of 1673 individuals were examined. One hundred and eighty five (11.06%) had microfilariae of Onchocerca volvulus in their skin biopsies, and of these infected people, five (2.7%) were blind. The highest prevalence rate recorded was in Ngwan Madaki, where 51 (26.3%) of the 194 people examined were infected. The lowest percentage prevalence was recorded in Dogon Fili with four (1.95%) of the 205 people examined being positive. The proportion of infected people increased with age; and onchocercal lesions were significantly more common in older than in younger persons (P less than 0.05). There was no significant difference between infection rates in males and females (P greater than 0.05), although the overall percentage infection and the numbers of onchocercal lesions were higher in males than in females.