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目的 了解在人工灌溉水渠干渠内 ,常规药物灭螺对钉螺及感染性钉螺消长的影响。方法 在安徽钓鱼台水库灌区 ,根据当地灭螺规划 ,在其计划灭螺区干渠内选择螺情观察点 ,同时选非计划灭螺支渠为对照 ;2 0 0 2年12月～ 2 0 0 3年 11月份 ,每月沿渠两边系统抽样查螺 ,室内压碎鉴定死活 ,并观察感染血吸虫情况。常规药物灭螺的时间、方法、药量及实施均由当地业务部门确定完成。结果 灭螺前钉螺死亡率在干渠和支渠变化趋势基本一致 ;4月 2 0日干渠灭螺 ,灭螺后 10 ,37d时干渠钉螺死亡率分别为 2 4 4 6 %及 4 3 0 1% ,但 8月底为 1 2 5 % ,同期未灭螺的支渠钉螺死亡率变化不大 ;灭螺前干渠有 3个月、支渠有 1个月检出感染性钉螺 ,灭螺后 4～ 6月份在干渠仅于灭螺后 10d发现感染性钉螺 ,未灭螺支渠 5月份检出感染性钉螺 ;8月 31日以后钉螺感染率及感染性钉螺密度在干、支渠均上升。结论 在人工灌区的引水干渠内 ,常规药物灭螺在预防人群感染方面可能起一定作用 ,但对年度钉螺及感染性钉螺螺口消长的作用有限。
Objective To understand the effects of conventional drug snail-killing on the growth of snails and infectious snails in artificial irrigation canals. Methods In the Diaoyuantai Irrigation District of Anhui Province, according to the local project of snail control, the snail observation point was selected in the planned dry-zone of snail-killing zone and the non-planned snail branch was selected as the control. From December 2002 to 2003 In November, the system sampling snail was conducted monthly on both sides of the canal, indoor crushing and identification of living and death, and the observation of schistosomiasis infection. The time, method, dosage and implementation of conventional drug snail are all confirmed by the local business department. Results The mortality of Oncomelania snails before the snail was basically consistent with that of the trunk and branch channels. On April 20, the mortality rates of snail on the trunk canal were 2446% and 4301% respectively at 10 and 37 days after the trunk quarantine, But it was 115% at the end of August. The death rate of snail on branches did not change much in the same period. The former had 3 months before the snail and 1 month after the branch canal was infected. After 4 to 6 months after snail killing, Infectious snails were found on the main canal only 10 days after the snail molluscs were treated, and the infecting snails were found on the untempered snail channels in May. After August 31, the infection rates and the infective snail density were increased in the dry and branch channels. CONCLUSION: In the irrigated trunk canal of artificial irrigated area, the conventional drug snail control may play a role in preventing human infection, but it has a limited effect on the annual snail and the infecting snail screw.