Schistosoma mansoni Cercaria and Schistosomulum Antigens in Serodiagnosis

Schistosoma mansoni cercaria and schistosomulum obtained in vitro were used in im-munofluorescence (IF) tests and indirect hemagglutination (IHA) tests of 137 study sera, 44 from subjects infected with S. mansoni and 93 from healthy subjects residing outside areas endemic for the disease. The results of these tests were compared with those obtained by testing the same sera using conventional adult worm antigen, and also with the initial clinical and parasitologic diagnoses of the 137 subjects providing the study sera. Regarding sera from acute versus chronic cases, IF testing of the acute sera consistently detected 1gA antibodies along with 1gM and IgG, the last two being found consistently in chronic sera. Also, the geometric mean of the 1gM antibody titers found in the IF tests was higher for acute than for chronic sera. Excluding IF IgA, which was negative for chronic cases, the sensitivity of the other types of tests (IF IgG, IF lgM, and IHA) using cercaria nd schistosomulum antigens, both under evaluation, ranged from 0.773 to 0.955, the specificity ranged from 0.957 to 1.000, the efficiency ranged from 0.927 to 0.985, the predictive value of positives ranged from 0.909 to 1.OOO, and the predictive value of negatives ranged from 0.903 to 0.979. No statistica