Onchocerciasis in the Benue State of Nigeria. IV. The prevalence of the disease among the population in Manor.

Between January and December 1981, parasitological and symptomatological methods of diagnosis were used to survey the prevalence of onchocerciasis among the human population in the Manor area of the Benue State of Nigeria. Hospital records of different health establishment all over the state were also examined to assess the status of the disease in the state. 911 or 69.8% of the 1306 persons examined were positive for microfilariae of Onchocerca volvulus; 135 or 10.3% had visual impairment including total blindness; 377 or 28.7% carried nodules with greater number of nodules found on the lower part, especially on the pelvis, than the upper part of the body. Skin conditions such as intense itching, depigmentation, lichenification and atrophy were regularly found in infected persons. Generally, the incidence was higher in males than females and there was always increased severity with advancing age. Hospital records also show that the infection is widespread in the state. The status of the disease in Manor is discussed and it is concluded that the area is hyperendemic for human onchocerciasis.