环境变化对钉螺扩散影响规律研究

钉螺扩散是血吸虫病传播的最主要途径。综述了目 前关于环境因素对钉螺生存和扩散影响方面的研究，分析了温度、纬度、高程、水位、土壤 植被等环境要素对钉螺影响的程度。指出生态扩散是钉螺扩散的最基本过程。研究了环境变 化和人类活动对钉螺扩散的影响，并对影响机理进行了初步探讨，结果表明：温度对钉螺扩 散的影响是一个缓慢的过程，研究短时间（几年或几十年）钉螺扩散变化主要考虑洪涝灾害 等因素的影响；洪水对钉螺扩散影响具有两面性，洪水年水位抬高将抑制钉螺的生长，同时 洪涝灾害使钉螺从有螺地区向无螺地区扩散，因此出现洪灾后钉螺数量先减少后增加的现象 。

Impact of Environment Changes on Oncomelania Spread

Oncomelania diffusion is the major way of spreading schistosomiasis.Based on the relation between environmental factors and oncomelania subsist,the influences of environmental elements such as temperature,latitude,elevation,water level,soil vegetation etc.on oncomelania subsist,and of environmental changes and human activities on the spreading of oncomelanias,are analysed.A viewpoint is presented that eco-propagation is the fundamental power of oncomelanias spread.The study results show that the oncomelanias spread is a slow progress,and that,with a short time(a few years or decades),the flood is the most important factor to influence oncomelanias spread.Flood influences have two effects: on one hand,when flood water level raises,oncomelanias proportion is restrained;on the other hand,flood can spread spiral shells to areas without oncomelanias.So the oncomelania quantity reduces first but increases following the flood.