江苏省血吸虫病传播阻断地区钉螺消长情况监测研究

通过对江苏省１９８１年以来逐年达到血吸虫病传播阻断标准（简称“达标”）的２９个县（市、区）钉螺消长情况的纵向监测研究，进一步揭示了残存钉螺的分布及消长特点，同时对钉螺监测方法也进行了探讨。结果表明：５５．１７％的县（市、区）在“达标”后出现钉螺，并且残存钉螺大多（７７．３７％）出现在“达标”后５年内，最长间隔达１２年仍可出现钉螺；“达标”后钉螺消长符合残存螺点螺口消长规律；在历史有螺环境“复现”的螺点多呈低密度小面积，一般与灭螺质量有关，而“新发现”螺点相对面积较大，密度较高，甚至还可出现感染性钉螺，常与钉螺扩散、查漏或漏查有关；螺情监测表明查灭螺质量是出现残存钉螺的主要因素，邻近扩散和外来输入也不容忽视；钉螺监测方法研究显示：“定点查”检出率明显高于“普查”和“轮查”。建议采用不同方法组合进行监测查螺，特别在“达标”后近５年要加强历史有螺环境的监测，远期监测则侧重外来输入。

SURVEILLANCE ON SNAIL HABITAT AREAS AFTER SCHISTOSOMIASIS TRANSMISSION BEING INTERRUPTED IN JIANGSU PROVINCE

The surveillance on snail habitat areas and distribution of residual snail have been carried out in 29 counties (cities, districts) early or later in Jiangsu Province since 1981 after the schistosomiasis transmission being interrupted. Besides, the methods for snail surveillance were also explored. The results showed that the snail could be redetected in 55.17% counties (cities, districts), and 77.37% of the snail habitats were detected in 5 years after surveillance. The longest interval of snailfree remained 12 years after surveillance. The growth and decline of snail after schistosomiasis transmission being interrupted conforms to the regularity of residual snail population. Most of the redetected snail sites were smaller in size (less than 1000 m2) and lower in density which was caused by poor snail control activities. But the newly detected snail sites were relatively larger in size, higher in density,and infected snail could even be found, which was related to snail extention, miss or fail in snail screen activities. The study of snail surveillance showed that the quality of snail screen and control was the main factor related to residual snail situation but snail extention from nearby habitats or imported snail also could not be neglected. The methods for snail surveillance showed that fixed spot method was better than that of general sampling survey method or turning over method It has been suggested that combination methods have to be applied in snial surveillance. Within 5 years after schistosomiasis transmission being interrupted, the surveillance on historical snail habitats should be strengthened but imported snail be stressed in long term surveillance