Onchocerciasis in Taraba State, Nigeria: intensity, rate of infection and associated symptoms in 14 communities of Bali district.

An epidemiological study of 14 communities situated along the major road passing through Bali district in Taraba State, Nigeria, was carried out in continuation of a statewide filariasis survey which began in 1989. Of the 4,024 people that were examined for Onchocerca volvulus microfilaria and for clinical symptoms of the disease, onchocerciasis, an unusually low 13.3% prevalence rate was recorded with a range between 1.1% and 45.5%. Only one community had prevalence rate beyond 30.0%, six had infection rates between 10 and 29% while the remaining seven had less then 10% prevalence of the disease. However, infection was recorded in every community. The prevalence of physical symptoms was equally low. Pruritus was 7.3% and leopard skin was 0.4%. The prevalence of onchocerciasis increased with age in both male and female thus supporting the age and sex specific pattern of infection that had been reported in other parts of the state. A case is made for the continued prospection for onchocerciasis in the other districts of the state in order to identify and treat all communities that must benefit from the ongoing ivermectin treatment.

Non-ocular clinical onchocerciasis in relation to skin microfilaria in the Taraba River Valley, Nigeria.

Examination of 2,876 persons in fourteen communities was carried out for clinical onchocerciasis on the Taraba river valley, Nigeria, where parasitological findings indicate unusually high endemicity. Forty-five percent of the population had at least one type of skin lesion or the other, the commonest of which was pruritus. Thirty-two percent had nodules. Some of the nodules were located in unusual sites such as the mammae, anus. Nodule carriage and nodule-load as well as lymphatic enlargement were higher than those recorded elsewhere in Nigeria and tended to increase with increase in age. When subjected to regression analysis, the relationship between skin lesion, nodule carrier rate, nodule load, scrotal enlargement and microfilaria rate (mf) on one hand and microfilaria density (mfd) on the other showed a near-perfect correlation. The findings of this study suggest that certain clinical manifestations of onchocerciasis may be a reliable and more rapid alternative to the parasitological approach in the assessment of the prevalence and severity of the disease in communities with similar socioecological characteristics.