Simple assay for detection of circulating antigens in children infected with schistosomiasis.

The ability of monoclonal based dot-ELISA and a previously described solid-phase ELISA were directly compared to detect circulating schistosomal antigens in sera from 50 Egyptian individuals with parasitologically proven schistosomiasis. The mAb employed, 128C3/3/21, recognized a repeating carbohydrate epitope expressed at all stages of the parasite development. The same mAb and patient serum samples were used i both tests, 17 samples from age-matched individuals infected with other parasites but not with Schistosoma were also tested. In the dot-ELISA, 44 serum samples (88%) were found to contain parasite antigens when screen at a dilution of 1;24, 43 serum samples (86%) were positive in the solid-phase ELISA at 1:8 dilution and only 37 (74%) samples were positive at 1:24 dilution. The specificity of the dot-ELISA was 93% as compared to > 99% for the solid-phase ELISA. The detection limit of dot-ELISA was 0.01 ng/ml, whereas only > 1 ng/ml could be detected by the solid-phase ELISA. As dot-ELISA does not require radioactivity or sophisticated equipment, so it is practically well suited for use in endemic areas in developing countries.