The status of human filariasis in relation to clinical signs in endemic areas of the Niger Delta.

A study was carried out in selected parts of the Niger Delta Basin on human filariasis and its relationship to clinical signs. One hundred and seventy-six (13.0%) of 1351 individuals examined were infected with microfilaria. Forty-six percent of microfilaria positive cases had M. perstans; 25.6% had W. bancrofti, 19.3% had L. loa, and 9.0% had O. volvulus. The prevalence of filariasis increased with age. Microfilarial density was generally low, 28.4% of infected individuals had counts of 50-100 microfilaria per 20 mm3 blood, 12.5% had counts less than five microfilaria per 20 mm3 blood. Onchocerca microfilariae did not exceed five microfilaria per snip. Microfilarial density was high among individuals aged between 20 and 49 years, but declined with increasing age above 50 years. Acute clinical signs of febrile attack, sink eruptions, and chronic clinical signs of chyluria, hydrocoele, elephantiasis and ocular lesions were observed in 61.9% of infected individuals, 73.4% of clinical cases were febrile attack and skin eruptions, 5.5% were chyluria, 12.8% were elephantiasis of the leg and scrotum, 7.3% were hydrocoele and 0.9% were ocular lesions. Chronic clinical signs were more prevalent in individuals over 40 years of age.