Abstract: Objective　To investigate the spatio?temporal distribution characteristics of Oncomelania hupensis snail habitats in three cities of Suzhou, Wuxi and Changzhou along the Taihu Lake region, so as to provide technical supports for establishing a sensitive and highly effective surveillance and forecast system for schistosomiasis. Methods　Snail distribution data were collected from Suzhou, Wuxi and Changzhou cities from 1950 to 2018, and the changing trend for snail habitats were described over years. In addition, the clusters of snail habitats were detected using Kernel density analysis and SaTScan space?time scan analysis. Results　The number of snail habitats appeared a single?peak distribution in Suzhou, Wuxi and Changzhou cities from 1950 to 2018, which peaked in 1970 and then declined rapidly. There were 62.68% of snail habitats eliminated within 10 years after identification, of which 38.24% were eliminated at the year of identification. Kernel density analysis and SaTScan space?time scan analysis revealed that high?density clusters of snail habitats were mainly distributed in Kunshan City, Wuzhong District and Xiangcheng District from 1970 to 1980, and in Yixing City in 1990; since then, the clusters gradually shrank, and overall appeared a move from northeast to west of Taihu Lake. A total of 4 new clusters were detected after 1970, as revealed by space?time scanning of snail habitats. In current snail habitats, emerging snail habitats are mainly identified in Huqiu District (Dongzhu Town), Wuzhong District (Guangfu Town), Taicang City (Shaxi Town) and Jintan District, and re?emerging snail habitats are scattered in 7 districts. Conclusions　The distribution of snail habitats are spatio?temporal aggregation in Suzhou, Wuxi and Changzhou cities. The monitoring and prediction of emerging and re?emerging snail habitats are the key points in the future.

Key words: Oncomelania hupensis, Cluster, Space?time scan, Kernel density analysis

摘要： 目的　分析太湖流域江苏省苏州市、无锡市和常州市（苏锡常地区）有螺环境时空变化规律，为建立敏感高效的血吸虫病监测预警体系提供参考依据。方法　收集1950–2018年苏锡常地区有螺环境资料，描述历年有螺环境变化趋势，并采用核密度分析和SaTScan时空扫描分析法探测有螺环境聚集区域。结果　1950–2018年，苏锡常地区有螺环境数呈单峰分布，于1970年达到峰值，随后快速下降。62.68%的有螺环境在发现后10年内被消除，其中当年发现并被消除的有螺环境占38.24%。核密度分析和SaTScan时空扫描分析显示，1970–1980年苏锡常地区有螺环境高密度聚集区主要分布在昆山市、吴中区和相城区，1990年高密度聚集区转移到宜兴市；随后有螺环境聚集范围逐渐缩小，总体呈现从太湖东北部向西部移动。1970年后新发现的有螺环境进行时空扫描分析共发现4个聚集区。现有钉螺环境中，新现有螺环境主要分布在虎丘区（东渚镇）、吴中区（光福镇）、太仓市（沙溪镇）和金坛区；复现钉螺环境分布较分散。结论　苏锡常地区有螺环境在时空上呈现聚集性分布，新现和复现有螺环境监测和预测将是今后血吸虫病防控工作的重点。

关键词: 钉螺, 聚集区, 时空扫描, 核密度分析