Efficacy of praziquantel against Schistosoma japonicum: field evaluation in an area with repeated chemotherapy compared with a newly identified endemic focus in Hunan, China

This study conducted in 1999/2000 was designed to evaluate the efficacy of praziquantel against Schistosoma japonicum in an area with repeated chemoth erapy (Area A) compared with a newly identified endemic focus (Area B) in H unan Province, China. The population size was 2015 and 2180 in Areas A and B, respectively, of which 1129 and 1298 subjects received stool examination . A total of 230 subjects were identified by the Kato-Katz technique (4 sme ars per person) as being infected with S. japonicum, 124 in Area A (prevale nce 11 %) and 106 in Area B (prevalence 8.2%). They were treated with a sin gle oral dose of praziquantel (40 mg/kg) in the non-transmission season. A follow-up stool examination was made 50 days after treatment. Among the 220 cases followed, 22 were found stool-egg-positive, with an overall cure rat e of 90 %, and 99 % reduction of infection intensity (eggs per gram stool). No significant difference was found in cure rates between the 2 areas (89. 7% vs 90.3%). The efficacy of the drug in the area with repeated chemothera py was not significantly different from that in the newly identified endemi c focus. This study, therefore, suggests that the efficacy of praziquantel against S. japonicum has not changed in the Dongting Lake region after more than 14 years of mass chemotherapy, and there is no evidence of tolerance or resistance of S. japonicum against praziquantel.