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在云南省巍山县石头地村现场饲养条件下,观察了90个人工感染的阳性钉螺逐月逸蚴的情况。每月均能逸蚴的阳性钉螺占20％,间断性逸蚴的阳性钉螺占42.2％。37.8％的阳性钉螺逸放尾蚴数次后不再逸放尾蚴。对此类钉螺的解剖发现,有的已无尾蚴和胞蚴存在。 对304个自然感染的阳性钉螺也进行了逐月逸蚴观察。各月未逸出尾蚴者作抽样解剖。结果,第1次逸蚴后2个月估计转阴的钉螺约占36.1％,3个月占50％,4个月占41％,5个月占39.8％,6个月占2.6％。
Under the conditions of field feeding in Shitou Village, Weishan County, Yunnan Province, 90 cases of positive snails infected with cercariae were observed monthly. Postive larvae can account for 20% of the monthly positive larvae, and 42.2% of the positive snails of the intermittent larvae. 37.8% of the positive snail escaped cercariae cercariae after several times no longer emit cercariae. Anatomy of such snails found that there are some cercariae and cercariae exist. 304 naturally infected snails were also observed by monthly larvae. Each month did not escape cercariae for sampling anatomy. As a result, 36.1% of negative snails were estimated to be negative at 2 months after the first larvae, 50% at 3 months, 41% at 4 months, 39.8% at 5 months and 2.6% at 6 months.