A COMPARATIVE-STUDY ON IGC-ELISA, IGM-IFT AND KATO-KATZ METHODS FOR EPIDEMIOLOGIC PURPOSES IN A LOW ENDEMIC AREA FOR SCHISTOSOMIASIS

The high sensitivity and the possibility of automation of the enzyme-l inked-immunosorbent-assay (ELISA) has indicated this technique as one of the most useful serological test for epidemiological studies. In th e present study, an ELISA for detection of IgG antibodies against adul t worm antigens (IgG-ELISA) was investigated for epidemiological pur p oses, in a rural area of the municipality of Itariri (Sao Paulo, Brazi l). Blood on filter paper (1,180 samples)from about 650 schoolchildren were submitted to ELISA and the data compared to the results of the p arasitological method of Kato-Katz and also to the IgM-IFT (immunofluo rescence test for IgM antibodies to gut associated antigens). The prev alence rates respectively of 8.5% 43.0% and 56.2% by the Kato-Katz, Ig G-ELISA, and IgM-IFT methods suggest the poor sensitivity of the paras itological method for detection of Schistosoma mansoni eggs in individ uals with low worm burden, situation commonly observed in low endemic areas. These results can partially explain the poor degree of agreemen t between the IgG-ELISA and the Kato-Katz, as suggested by the Kappa i ndex of 0.170. Otherwise the Kappa index of 0.675 showed substantial a greement between the two serological tests. Some discrepancy of result s between the two serological techniques must be better investigated.