Serodiagnosis of human Schistosoma mansoni infections: enhanced sensitivity and specificity in ELISA using a fraction containing S. mansoni egg antigens omega 1 and alpha 1.

Six fractions of Schistosoma mansoni egg homogenate obtained by cation exchange chromatography were tested in an enzyme-linked immunosorbent assay (ELISA) for their efficacy in serodiagnosis of human S. mansoni infections. One cationic fraction (CEF6) containing egg antigens omega 1 and alpha 1, was found to be highly reactive with a S. mansoni positive reference serum pool. 94 of 95 sera from individuals infected with S. mansoni gave a positive reaction with CEF6, and no cross reactivity was obtained with this antigenic fraction and sera from donors infected with heterologous non-schistosome parasites and cases of avian cercarial dermatitis. Only 10 of 165 sera from patients with S. haematobium and three of 10 sera from patients with S. japonicum were positive with S. mansoni egg CEF6. In one group of patients from West Africa, examined both serologically and parasitologically at a six-monthly interval, the measurement of antibody to CEF6 provided a more sensitive diagnostic aid than stool examination.