Studies on resistance of Schistosoma to praziquantel XIIV sensitivity of Schistosoma japonicum to praziquantel in marshland and lake endemic regions of Chinese Mainland

Objective To compare the sensitivities of different isolates of Schistosoma japonicum in marshland and lake regions of Chinese Mainland to praziquantel,so as to provide experimental evidence for establishing the techniques of detecting and monitoring praziquantel sensitivity.Methods Mice were infected with cercariae released from the S.japonicum-infected snails collected from the marshland and lake endemic regions of Hunan,Hubei,Jiangxi,Anhui and Jiangsu provinces,grouped,and treated with praziquantel at single oral doses of 37.5,75,150,300 mg/kg and 600 mg/kg,while mice infected but treated with 2.5% Cremophor EL served as controls.The worm burden reductions caused by praziquantel treatment were observed,and the 50% effective dose(ED50 value) was calculated.Results The administration with praziquantel at single oral doses of 37.5,75,150,300 mg/kg and 600 mg/kg achieved worm burden reductions of 10.37%-19.81%,23.22%-33.09%,39.25%-49.61%,62.87%-74.44% and 91.26%-98.09%,respectively,and no significant differences in worm burden reductions of different isolates of S.japonicum were detected following treatment with different doses of praziquantel(P 0.05).The praziquantel ED50 values against different isolates of S.japonicum ranged from 134.1 to 186.7 mg/kg,and no significant differences of praziquantel ED50 values were found among different isolates(P 0.05).Conclusions There were no significant differences of praziquantel sensitivities of different isolates of S.japonicum in marshland and lake regions of Chinese Mainland.Praziquantel ED50 value against schistosomes,as a quantitative index,can truly reflect the sensitivity of schistosome populations to praziquantel,which can be used to assess the risk of emergence of praziquantel resistance in schistosomes.