Onchocerciasis in the forest-savannah mosaic area of Nigeria

Abstract

An epidemiological survey of onchocerciasis and its transmission was undertaken at Achi in the forest-savannah mosaic area of South-Eastern Nigeria. Out of a total registered population of 14608, of whom 2282 were examined, 20.3% (462) had onchodermatitis and 22.4% (510) had nodules in non-lymph node areas. The prevalence of onchodermatitis and nodules showed an overall rise with age, peak between ages 30 and 39 years. The prevalence of skin microfilarial load was 45% and the community microfilarial load was 3.1mf/mg skin. These parameters also rose with age. Visual acuity was impaired in 35.4% of subjects while 3.9% were blind. In 16.5%, visual impairment was attributable to cataract. Transmission studies showed that simuiium damnosum was the dominant vector species. Biting by the vector was mostly between February and April during the afternoon. This study and many others reveal the serious health problem posed by river blindness in West African countries not covered by the Onchocerciasis Vector Control Programme. The socio-economic burden is considerable and justifies integrated control strategies including mass ivermectin distribution.

Keywords

• forest-savannah
• onchocerciasis