Effect of praziquantel in vitro on differentdevelopmental stages of Schistosoma japonicum

The effects of praziquantel in vitro on different developmental stages of Schistosoma japonicum indicated that no stage specific difference was seen with minimal effective concentrations required to induce worm stimulation and contraction. The worms on d 3, d 7, and d 11 required a 10-fold higher concentration of praziquantel to induce vesicles along the worm tegument when compared to adults (d 35 and d 42). When parasites were exposed to praziquantel 30 microg/mL for 15 min, only d 35 and d 42 worms were unable to recover completely. However, if the exposure periods were extended to 4 h d 3, d 7, d 11, and d 21 schistosomula recovered completely, while the worms of d 0, d 28, d 35 and d 42 appeared to be still abnormal. The results note that the susceptibility of different developmental stages of schistosome to praziquantel exhibits stage differences which essentially appear to be related to an interaction of the drug and the tegument.