中文摘要：

目的总结和分析我国传播控制（传控）地区病情和螺情逐年变化过程,探索达到传控标准前后钉螺指标变化对病情影响的规律,为今后我国修订血吸虫病传控标准中钉螺等相关指标,更科学、规范地考核和评价防治工作效果提供依据。方法选择全国8个省21个已达传控或传播阻断（传阻）阶段的湖沼型和山丘型血吸虫病流行县,采取回顾性调查方法,收集、记录各调查县达到传控标准前10年和以后各年的疫情资料,建立全国疫情回顾性调查数据库;分析不同年份钉螺和感染螺、人群血吸虫感染率等变化趋势,以及达标前后不同流行类型和疫情类别地区螺情和人群感染率等疫情指标的变化趋势和变化规律。结果在达传控标准前,流行区人群血吸虫感染呈逐年下降趋势,湖沼型流行区人群平均感染率在达传控前4年左右已降至〈5%,山丘型流行区则在达标前8年左右已降至〈3%;两类地区在传控达标年平均感染率分别降至2.10%和1.45%,但在达传控后3～4年开始出现回升,且回升多发生在湖沼型流行区。湖沼和山丘型流行区钉螺分布面积和密度,均在达传控前10年开始逐年下降,其有螺面积占历史累计有螺面积较传控达标年分别降至最低点的2.75%和0.55%,活螺平均密度在达传控前3～4年至达传控后9～10年间保持较低水平;但在传控达标年后6～7年开始出现新发现钉螺环境,9～12年后出现钉螺面积和活螺密度回升。结论湖沼和山丘型流行区在达传控后螺情能维持10年左右的较低水平而无明显波动,但病情在达传控后5年左右即出现反弹。在实施以传染源控制为主的综合措施时,仍应重视对钉螺的控制和监测工作,并建议今后在修订我国血吸虫病传控标准时,应将＂钉螺面积下降比例＂和＂感染性钉螺控制＂作为达标验收指标。

英文摘要：

Objective To summarize and analyze the process of the changes of schistosomiasis infection and Oncomelania snails in schistosomiasis transmission-controlled areas to explore the rules of the impact of changes of snail indexes on human infection before and after the stage of transmission control,so as to provide the evidence for editing snail indexes in the schistosomiasis controlled criterion and a more scientific,standardized control assessment and evaluation.Methods Twenty-one schistosomiasis transmission-controlled or transmission-interrupted counties in lake endemic areas and hilly endemic areas in 8 provinces were selected and investigated retrospectively to collect schistosomiasis epidemiological information 10 years before these counties reached the criterion of transmission control and the subsequent years until 2008 or 2009.A ＂Standard county schistosomiasis epidemic survey data review software＂was developed to establish a national epidemic retrospectively database;the trends of changes of snail status,infected snail status and human infection status were analyzed in different years.The trends and rules of the changes of snail areas,emerging snail areas,living snail densities,infected snail densities,snail infection rates and human infection rates were analyzed and compared before and after the counties reached the schistosomiasis transmission-controlled criterion in different types of endemic areas.Results Before the transmission control,the human infection rate presented a declining trend in endemic areas.In lake endemic areas,the human infection rate declined to below 5% 4 years before the transmission control;in hilly endemic areas,the human infection rate declined to below 3% 8 years before the transmission control,and the human infection rates of the lake and hilly endemic areas declined to 2.10% and 1.45%,respectively,at the year of transmission control.However,3 to 4 years after transmission control,the disease began to rebound,especially in lake endemic areas.The snail areas and snail densit