Immunodiagnosis of recently acquired Schistosoma mansoni infection. A comparison of various immunological techniques.

A group of Dutch tourists, who became infected with Schistosoma mansoni in Ethiopia, was investigated in a serological follow-up study, during 8-50 weeks after infection. The following immunodiagnostic tests were applied: (1) the immunofluorescent antibody (IFA) test, both on frozen sections of adult worms, and in a modification for the detection of antibodies against gut-associated polysaccharide antigens; (2) the enzyme-linked immunosorbent assay (ELISA) with as antigens: adult worm antigens (AWA), cercarial antigens (CA), soluble egg antigens (SEA), and the purified antigens CAA and MSA1; (3) the defined antigen substrate spheres system with AWA as antigen in an immunofluorescence and immunoperoxidase modification; (4) the indirect haemagglutination reaction with AWA; and (5) the immunoelectrophoresis with AWA and antigens of the intermediate host. With these techniques it could be shown that in all persons which had been in contact with S. mansoni infected water, also in those not excreting schistosome eggs or not showing clinical symptoms of infection, specific anti-schistosome antibodies were present. No false-negative reactions were found with the ELISA with cercarial antigens, MSA1, or AWA-TCA, with the IFA detecting gut-associated polysaccharide antigens and with the immunoelectrophoresis. The highest titres were observed with the two techniques (IFA and ELISA) detecting antibodies against the gut-associated polysaccharide antigen CAA.