A rapid-format antibody card test for diagnosis of onchocerciasis

Improved methods are needed for field diagnosis of onchocerciasis, to suppo rt efforts aimed at elimination of the disease. A rapid-format card test wa s evaluated that detects IgG4 antibodies to recombinant Onchocerca volvulus antigen Ov16 with serum samples from patients with onchocerciasis and with various types of control serum samples. The sensitivity of the test with s erum samples from 106 microfilariae-positive subjects was 90.6%. The test w as equally sensitive with serum samples obtained from patients in Africa an d Latin America. Specificity was excellent; positive tests were observed fo r 2 of 38 serum samples from patients with other filarial infections and fo r 1 of 23 serum samples from patients with nonfilarial helminth infections. The 3 "falsepositive" serum samples were from West Africans who could have been coinfected with onchocerciasis. No positive tests were observed with nonendemic serum samples from normal adults, patients with autoimmune disor ders, or patients with the hyper-IgE syndrome. This new test holds great pr omise as a simple tool for diagnosis of onchocerciasis.