Efficacy of an enzyme-linked immunosorbent assay in the diagnosis of and serologic distinction between acute and chronic Schistosoma mansoni infection.

To determine the efficacy of an ELISA to diagnose and differentiate the clinical phases of schistosomiasis, serum from patients with acute (11) and chronic schistosomiasis (58), from individuals infected with other parasites (53), and from uninfected individuals (40) was analyzed for the presence of anti-schistosomal of IgG, IgM, and IgA antibodies. Immunofluorescence for IgM and IgA antibodies was also performed on serum from all patients and controls. The IgG antibodies against worm antigen (ELISA-w) were detected in all schistosomiasis patients, with only one false-positive result. The IgA antibodies were detected by ELISA-w in 81.8% of patients with acute disease and in only 5.9% of patients with chronic disease. In addition, the mean optical density values for IgM and IgA antibodies was statistically higher in the patients with acute disease than in those with chronic disease. The results of this study show that the use of a crude adult worm extract as an ELISA antigen can provide a serologic method with high sensitivity and specificity for 1) the diagnosis of acute and chronic schistosomiasis and (2) the serologic distinction between the two forms of the disease.