Microfilaruria in an area of Nigeria with hyperendemic onchocerciasis.

Urine samples collected from sixty-four Nigerians living in a community which is hyperendemic for onchocerciasis were examined for microfilaria. Each urine donor was examined for the physical symptoms of long-standing onchocerciasis. The microfilaruria rate was 23.4%. Males had a higher rate of microfilaruria (27.5%) than females (16.7%). The prevalence rates of leopard skin and nodules were 18.8% and 46.9%, respectively. Thirteen persons had microfilaruria and had nodules. Seventeen showed no microfilaruria but had nodules. Only two of those without nodules were without microfilaruria. A very strong association was found between nodule-possession, nodule-load and microfilaruria (coefficient of association 0.85). Nodule load seemed to be the major factor in having microfilaria in urine. Microfilaruria is not common in Nigeria and the present finding is the first report of microfilaruria in the Taraba river valley which is a continuous onchocerciasis zone with the Western Cameroun-Southern Chad focus of transmission where microfilaruria has been reported. This paper discusses the implications of the results of this investigation with respect to monitoring the impact of ivermectin distribution in the Taraba river valley of Nigeria.