Abstract: AIM: To compare 3 different methods of detecting the circulating antigen (CAg) to evaluate the chemotherapeutic effect in treatment with patients with schistosomiasis Japonica by praziquantel.METHODS: Serum CAg was detected in patients by Dot-ELISA, Sandwich-ELISA and R-IHA, based on monoclonal antibody (MAb) JPG3.The reverse negative rates were analyzed at six months, one year and two years after treatment with praziquantel 50 mg·kg^-1 (one dosage).RESULTS: The reverse negative rates of CAg in serum treated with praziquantel were 75.8 %, 72.6 %and 43.5 %at six months (P<0.01), 83.9 %, 88.7 % and 71.0 % at one year (P<0.05), and 87.1 %, 95.2 % and 93.5 % at two years (P >0.05) by Dot-ELISA, Sandwich-ELISA and R-IHA, respectively.The geometric mean reciprocal titer (GMRT) in positive individuals declined constantly at six months, one year and two years.CONCLUSION: Dot-ELISA and Sandwich-ELISA are better than R-IHA in evaluation of chemotherapy effect of praziquantel at six months and one year, whereas Sandwich-ELISA is more objective than Dot-ELISA for reading results.All of three assays have no significant difference after two years of treatment.TheGMRT that reflects circulating antigen level can also assess the cure after chemotherapy with praziquantel to a certain extent.

Key words: praziquantel, schistosomiasis, circulating antigen, evaluation of chemotherapy effect, monoclonal antibody