浙江省钉螺分布抽样调查

目的　了解浙江省钉螺及感染性钉螺分布 ,为制定血吸虫病防治计划提供科学依据。　方法　采用分层整群随机抽样法抽取调查点,5m系统抽样结合环境抽查2框方法查螺,压碎法检查钉螺感染情况,设置假螺点考核查螺质量。　结果　在全省55县7106个村中抽取34县的100村为调查点,在21县的32村中查出有螺条块223个,1572框有螺,有螺面积73300m2。其中山丘型18县29村有螺,有螺面积72640m2,占总数的99.1%,与水网型比较差异具有显著性(t=3.04,P<0.01);1,2层有螺面积71680m2,占总数的97.8%,与 3层比较差异具有显著性(t=3.71,P<0.01);沟和渠有螺面积占总数的62.6%,显著高于田环境(t=3.02,P<0.01)。解剖活螺7892只,均阴性。推算全省有螺面积理论值为1361940m2 。　结论　估算浙江省当前有螺面积1500000～2000000m2,主要分布在山丘地区近4年内有螺村,以沟渠为主,但未查到感染性钉螺。

A Sampling Survey on the Distribution of Oncomelania Snails in Zhejiang Province

Objective To find out current distribution of Oncomelania snails and Schistosoma infection in snails in Zhejiang Province, so as to improve the project of schistosomiasis control. Methods Investigation spots were selected by stratified cluster sampling method, 100 villages of 34 counties were selected from 7 106 villages of 55 counties as survey spots. Synchronously systematic and environmental samplings were used for the survey. Snails were dissected to determine the infection status and spots with sham snails were set to assess the quality of the survey. Results The result showed that snails were found in 223 strips, 1 572 frames and 73 300 m 2 area in 32 villages of 21 counties. Snails were found in an area covering 72 640 m 2 in 29 villages of 18 counties in hilly region, which accounted for 99.1% of total snail habitats. The significantly larger area with snails was revealed in hilly region than that in water network region (t=3.04, P<0.01). 1 st, 2 nd strata occupied 71 680 m 2 snail area, which accounted for 97.8% of total snail area, much higher than that in the 3 rd stratum (t=3.71, P<0.01). Snail habitats in the irrigation ditches and canals accounted for 62.6% of total snail area, significantly higher than that of farmland (t=3.02, P<0.01). No snails were found infected among 7 892 living snails by dissection. The theory value of snail area in Zhejiang Province was 1 361 940 m 2. Conclusion It is estimated that the snail-ridden area is about 1 500 000-2 000 000 m 2in the Province, mostly found in the villages of hilly region with a record of snail habitats during the recent 4 years and the primary environment of the snail areas were ditches and canals. No infected snails were found from the survey.