Diagnosis of Onchocerca volvulus infection in Guatemalan children.

Nodule examination, the Mazzotti test (a provocative challenge with diethylcarbamazine), and the enzyme-linked immunosorbent assay (ELISA) were compared for diagnostic efficacy in children who were born in an area endemic for onchocerciasis in Guatemala and were skin-biopsy negative for microfilaria of Onchocerca volvulus. Four groups of children under 16 years of age were formed based upon the possible combinations of nodule positivity or negativity and ELISA positivity or negativity. Only those children with a positive (greater than or equal to 1:160) ELISA titer had a positive Mazzotti test (9 of 20 tested), regardless of the presence or absence of nodules. These results suggest that the current ELISA serology is highly sensitive for low density infections, and should be considered in surveys for the incidence of new Onchocerca infections.