For the qualitative determination of serum or plasma antibodies in humans, primarily IgG, to Schistosoma spp. using the ELISA technique. During the first incubation, the antibodies in the patients' serum bind to the antigens in the test well. The next incubation allows the enzyme complex to bind to teh antigen-antibody complex. After a few washings to remove unbound enzymes, a substrate is added that develops a blue color in the presence of the enzyme complex and peroxide. The stop solution ends the reaction, turning the blue assay color to yellow.