COLLABORATIVE STUDY ON ANTIGENS FOR IMMUNODIAGNOSIS OF SCHISTOSOMIASIS

Abstract

Eight research laboratories in Europe and the USA were selected, on the basis of having published data on Schistosoma mansoni and S. japonicum antigens, to participate in a study of various antigen/test combinations for immunodiagnosis of schistosomiasis. The serum bank consisted of 395 well documented sera from 4 endemic areas in Brazil (2 areas), Kenya and the Philippines. Altogether, 21 S. mansoni and 4 S. japonicum antigen and immunoassay combinations were evaluated. S. mansoni egg antigens yielded a higher combined sensitivity than adult worm antigens, irrespective of their purity, in active S. mansoni infections before and after specific treatment. Quantitative seroreactivity of characterized S. mansoni egg antigens showed good correlation with fecal egg counts in the 5-14 yr age group. No correlation between morbidity related to S. mansoni and seroreactivity was observed in any test system. Three S. japonicum egg antigens showed high sensitivity and specificity in relation to the presence or absence of eggs in the stool. The quantitatives seroreactivity of the characterized S. japonicum egg antigens correlated directly with the intensity of S. japonicum infection in all age groups. The enzyme-linked immunosorbent assay (ELISA), using several different procedures, performed well with the antigens used in the study. The indium slide immunoassay (ISI), a simple qualitative visual test system using an S. mansoni egg antigen, demonstrated a high degree of sensitivity and specificity. The results did not indicate the superiority of any particular immunodiagnostic method for detecting antischistosome antibodies. This may be a 1st step towards developing and standardizing antigens for immunodiagnosis of schistosomiasis.