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目的：了解云南大山区感染性钉螺的季节变化规律。方法：在云南省巍山县高原峡谷型流行区选择两片独立而相邻的自然环境为观察区，逐月调查土表、土层钉螺和感染性螺分布情况。结果：表明大山区全年均可查见感染性钉螺，夏季钉螺感染率较低，秋季则明显升高，以后呈下降趋势，一直持续到翌年雨季仍有感染性钉螺存活。感染性螺以土表分布为主，土层内仅占少数。结论：５至６月田间放牧的牛粪污染是产生感染性钉螺的主要原因；提示在春耕栽插之前进行人畜同步化疗可减少感染性钉螺密度；如果改春季查螺为秋季查螺可减少感染性螺点的遗漏。
Objective: To understand the seasonal variation of infectious snails in mountainous areas of Yunnan. Methods: Two independent and adjacent natural environments were selected as the observation area in the plateau gorge area of Weishan County, Yunnan Province. Soil distribution, snail and infectious snail distribution were investigated monthly. Results: Infectious snails were found in large mountainous areas throughout the year. Infection rates of snails in summer were low, but they were significantly higher in autumn, and then declined until the next consecutive year. Infectious snails survived in the rainy season the following year. Infectious snail mainly distributed in the soil surface, only a minority within the soil layer. Conclusion: Cow dung pollution from May to June was the main reason of infecting snails. Simultaneous chemotherapy of human and animals before spring planting could reduce the density of infectious snails. If the snail was changed in autumn, the infection could be reduced in autumn Missing point of the spiral.