This study nas ained to monitor the current susceptibility of S. Japonicum in cercariae stage to praziquantel. The cercariae were e×posed in -5 × 10-5, 10-5, 5 × 10-6, 10-6, 5 × 10-7, and 10-7 mol/L praziquantel solution for 20,40,60,80, and 100min,and then the changes in the patterns of behavior,including swimming,contraction,tail shedding and death, were observed under a microscope. Results shown that during the observation, some of the cercariae were dead before tail shedding when it were e×posing in -5 × 10～° mol/L praziquantel solution, while all of the death of the cercariae occurred after the tail shedding when they were e×posed in 10-5, 5× 10 -6, 10 -6, -5 × 10 -7, and 10-7 mol/L praziquantel solution and mortality were always lower than the tail shedding rates of cercariae at the same time point. When the cercariae were e×posed in 10-6 mol/L praziquantel for 80min,the tail shedding rate of cercariae was 92. 2%(SD 1. 8%) ; when in 10-6 mol/L praziquantel for 100min, the tail shedding rate of cercariae was 97. 7% (SD 2. 7%). E×posing to 10-6 mol/L praziquantel for 20, 40, 60, 80, and 100min, the tail shedding rates of the cercariae between the groups of epidemic area had no significant difference (P = 0. 8-51), the tail shedding rates of the cercariae had significant difference in different time(P<0. 001). In conclusions, there was no significant difference in the responses to praziquantel at the cercariae stage among S. Japonicum isolates in the epidemic areas around the Poyang Lake. E×posing to 10-6 mol/L praziquantel for 80min or lOOmin, the tail shedding rates of the cercariae were stable.%目的 测定当前鄱阳湖区日本血吸虫尾蚴对吡喹酮的敏感性.方法 1.将尾蚴分别暴露于5×10-5 、10-5、5×10-6、10-6、5×10-7、10-7 mol/L的吡喹酮溶液中,作用20、40、60、80、100 min后解剖镜下观察尾蚴泳动、收缩、断尾的变化以及死亡情况.结果 1.在观察时间内,暴露于5×10-5 mol/L吡喹酮溶液中有的尾蚴在断尾前死亡,暴露于10-5、5×10-6、10-6、5×10-7、10-7 mol/L的吡喹酮溶液中尾蚴的死亡均发生在断尾之后,且同一观察时间点的尾蚴死亡数均低于断尾数.其中在10-6mol/L吡喹酮溶液中作用80 min,尾蚴断尾率为92.2%(s ±1.8%); 作用100 min,尾蚴断尾率为97.7%(s ±2.7%).2.暴露于10-6mol/L吡喹酮溶液中作用20、40、60、80、100 min,各疫区组间的尾蚴断尾率无显著差异(P=0.851),不同时间下尾蚴断尾率差异有统计学意义(P<0.001).结论 鄱阳湖区血吸虫病重疫区各现场分离株日本血吸虫尾蚴对吡喹酮的敏感性无明显差异.将尾蚴移入10-6mol/L吡喹酮溶液80或10 0min,镜下观察其断尾率较为稳定.
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