氯硝柳胺展膜剂杀尾蚴试验

Experiment on killing schistosomiasis cercariae by niclosamide spreading agent

目的观测氯硝柳胺展膜剂水面杀日本血吸虫尾蚴的效果。方法 1)直接杀蚴试验。取3047FALCON细胞培养盒,注入去氯水,放入尾蚴,再滴加3.4、1.7、0.8、0.4和0.2μl,氯硝柳胺展膜剂,分别记录5、10和30 min尾蚴死亡数。2)室内杀蚴感染实验。取4只圆形塑料盆,注入去氯水15 L,水面积为0.163 m2。每盆移入尾蚴1 500条,静置0.5h。试验组3盆,氯硝柳胺展膜剂浓度分别为0.2、0.3和0.4 g/m2,施药5 min后,各放入小鼠20只感染30 min,同时设清水对照组,感染完成后放动物室进行常规饲养,35 d后剖杀,收集成虫计数。3)现场模拟试验。选择长为50 m,宽为2 m的沟渠2条,分别放置40只阳性钉螺逸蚴30 min后,试验组喷洒1%氯硝柳胺展膜剂0.3 g/m2,两组各放置小鼠20只/笼,每天感染4 h,连续2 d,室内饲养35 d后解剖。结果直接杀蚴试验1%氯硝柳胺展膜剂用量为3.4、1.7、0.8、0.4和0.2μl时,5 min尾蚴死亡率分别为97.83%、100%、26.67%、11.86%和18.84%;10 min分别为100%、100%、93.33%、74.19%和43.84%;30 min均为100%。室内杀蚴感染实验1%氯硝柳胺展膜剂用量为0.2、0.3、0.4 g/m2浓度时,小鼠感染率均为0%,清水对照组小鼠感染率为100%。模拟现场试验试验组小鼠感染率均为0%,对照组感染率47.37%。结论1%氯硝柳胺展膜剂现场喷洒杀尾蚴用量小,在水面铺展速度快,0.2 g/m2以上浓度杀蚴率100%。

Objective To observe the effect of niclosarnide spreading agent on killing schistosomiasis cercariae. Methods Three experiments were adopted. 1. Direct killing metacercaria test： we took 3047FALCON cell culture boxes, injected dechlori- nated water, put cercariae into them, dropped 3.4μl, 1.7μl, 0.8μl, 0.4μl or 0.2μl niclosamide spreading agent, and then recorded cercariae deaths in 5, 10 and 30 minutes. 2. Mouse infection test in laboratory： we took 4 round plastic basins, poured into 15 L dechlorinated water （with the water area of 0. 163m2 ）, and then had 1,500 cercariae in each basins for 30 minutes. There were 3 experimental groups with the concentrations of niclosamide spreading agent at 0.2 g/m2, 0.3 g/m2 and 0.4 g/m2 separately. After 5 minutes, we put 20 mice in each basin for 30 minutes then moved them into cages and bred them convention- ally. The water control group was set simultaneously. All mice were dissected after 35 days and then the adult worms were count- ed. 3. Mimic field test in killing metacercaria： we chose two ditches with length of 50 m and width of 2 m, and placed 40 posi- tive snails separately. After 30 minutes, the experimental group was sprayed 1% niclosamide spreading agent at 0.3 g/m2 , and then 20 mice in the experimental group and 20 mice in the water control group were exposed to infection in the two ditches, 4 hours a day for two days. Results Direct killing metacercaria test showed that for niclosamide spreading agent at doses of 3.4μl, 1.7μl, 0.8μl, 0.4μl and 0.2μl, the death rates in 5 minutes were 97.83%, 100%, 26.67%, 11.86% and 18.84% respectively; the death rates in 10 minutes were 100%, 100%, 93.33%, 74.19% and 43.84% respectively;and the death rates in 30 minutes were all 100 %. Mouse infection test in laboratory showed that when 1% niclosamide spreading agent was used at the concentrations of 0.2 g/m2, 0.3 g/m2 and 0.4g/m2, the infection rates of mice in the experimental group were all 0 %, while the infection rate of the mice in the water control group was 100 %. Mimic field test showed that the infection rate of mice in the experimental group was 0 %, while the infection rate in control group was 47.37 %. Conclusions One percent niclosamide spreading agent can kill schistosomiasis cereariae by field spraying at small doses and spreads quickly on the surface of water. The death rate of cercariae is 100 % when nielosamide spreading agent is added at concentrations of 0.2 g/m2 or above.