Abstract:

Objective To evaluate the in- vivo efficacy of three artemisinin derivatives artemether,artesunate and dihydroartemisinin against schistosomulum of praziquantel- resistant Schistosoma japonicum,.Methods The S. japonicum subjected to subcurative dose of praziquantel for 11 rounds was served as a praziquantel- resistant strain, while the field- derived strain without exposure to praziquantel was served as a praziquantel-susceptible strain. The mice infected with the two strains of cercaria were treated with artemether,artesunate and dihydroartemisinin at a single dose of 300 mg/kg by gavage in days 7 and 8 post- infection, respectively. All mice were dissected 45 days post-infection, and the adult worms were collected to estimate worm and female worm burden reductions caused by drug treatment. Results Administration of artemether, artesunate and dihydroartemisinin at a single dose of 300 mg/kg given on days 7 and 8 post-infection achieved total worm burden reductions of 69.8%-71.0% and female worm burden reductions of 75.4%-79.8% in mice infected with praziquantel- susceptible strain, whereas the same treatments reduced total worm burdens of 64.6%-66.1% and female worm burdens of 69.3%-71.1% in mice infected with praziquantel-resistant strain. There were no significant differences between the two strains. Conclusion Praziquantel-resistant S. japonicum remains sensitive to the three major artemisinin derivatives artemether, artesunate and dihydroartemisinin, and no cross-resistance is observed between praziquantel and artemisinin in S. japonicum.

Key words: Schistosoma japonicum, Praziquantel, Artemisinin, Dihydroartemisinin, Artesunate, Artemether, Cross-resistance