Summary
The prevalence of microfilaremia among a representative sample of the adolescents and adults in 13 Brazilian Amazon Indian villages was determined for July-August, 1976. With Giemsa-stained peripheral blood smears, preparations from peripheral blood lymphocyte cultures, or both, 533 persons aged 10 years and older and 68 children below age 10 were tested. Mansonella ozzardi was the only blood-borne microfilarial species found. Prevalence was highly village-specific. In four of 13 villages persons tested had no detectable microfilaremia by the methods used. In four other villages the overall prevalences for residents aged 10 years and older were in excess of 60% by one of the methods used. In villages where microfilaremia was documented only five (13%) of the total 38 children tested were positive. There was a general trend for prevalence to rise with increasing age. The ratio of the prevalence of microfilaremia among males to that among females was approximately 1.4:1 with peripheral blood smear test results but exactly 1:1 with the other method. In each of the five microfilaremia-positive villages tested using both methods, we detected a higher prevalence of microfilaremia with the preparations made from the lymphocyte culture studies.