The significance of guinea worm infection in the immunological diagnosis of onchocerciasis and bancroftian filariasis

Infections with Dracunculus medinensis frequently occur in the same geographical area as infections with Onchocerca volvulus and Wuchereria bancrofti. This study analysed the significance of D. medinensis infections for the specificity and sensitivity of available tests for antibody-based diagnosis of onchocerciasis (using individual recombinant clones OV-10, OV-11 and OV-16, and the OV-7/OV-10/OV-16 tri-cocktail, in an enzyme-linked immunosorbent assay) and for circulating antigen-based diagnosis of bancroftian filariasis (using the TroBio(TM) and the ICT(TM) card tests). Some immunological cross-reactivity was observed with all tests. When using individual recombinant O. volvulus antigens, the highest assay indices were obtained for clone OV-10, and the lowest: for clone OV-16. Testing the serum responses against the tri-cocktail of recombinant antigens did not notably improve the assay indices. Two of 40 serum samples from individuals with patent dracunculiasis gave a false positive response in the ICT(TM) test and one of these was also positive in the TropBio(TM) test. Possible implications of applying these diagnostic assays in areas endemic for dracunculiasis are discussed.