皖南山区残存钉螺的消长规律及影响因素

Change of status of remnant Oncomelania snails in south mountainous areas of Anhui Province

目的探讨山丘型血吸虫病流行区残存钉螺分布、消长规律及影响因素，为有效控制和消除残存钉螺提供科学依据。方法收集1994～2005年黄山市螺情监测数据和气温、降雨量等气象资料，分析残存钉螺分布特点、相互关系；选择有残存钉螺环境现场观察螺口消长和钉螺繁殖状况；选择2001～2005年施行药物灭螺的20个螺点，现场观察土表、土内钉螺分布情况和药物灭螺对残存钉螺的作用。结果1994～2005年螺情资料显示，残存钉螺主要分布在历史疫情较重的区（县）和复杂环境，查出的有螺环境数和有螺面积与历史有螺面积分布密切相关（r点=0．984、r面积=0．962，P均〈0．01）；年降雨量和3～5月降雨量对逐年查出的有螺环境数呈负相关（r年降雨=-0．618，r3～5月降雨=-0．590，P均〈0．05）；残存钉螺交配率最高达13．18％；药物灭螺对土表、土内残存钉螺杀灭效果显著。结论山丘型血吸虫病传播阻断地区螺情回升与历史螺情及环境有关；残存钉螺繁殖能力较强；加强历史有螺区药物灭螺可有效控制钉螺回升。

Objective To understand the distribution and change rule of status of the remnant Oncomelania snails in hilly areas, to evaluate the impact factors on the snails, and to provide basis for remaining snail control. Methods The data of snail surveillance and meteorological phenomena from 1994 to 2005 were collected and the snail distribution and its correlation with temperature and rainfall were analysed. The propagation and change of snail population were investigated in the habitats of the remnant snails. The snail distribution was investigated on 20 snail spots, which were found and controlled from 2001 to 2005. Results The remnant snails distributed mainly in the areas which had heavy epidemic situation before and complicated environments. The number of snail spots and its area had significantly correlation with snail distribution in history （r = 0. 984 and 0. 962 ,P〈0. 01） ,and the snail spots had significantly correlation with rainfall of a year and March- May（ryear=-0. 618,rMarch-May= -0. 590,P〈0- 05）. The highest mating rate was 13.18%. The molluscicide had good effect on the remnant snails in the surface layer of soil. Conclusions The rea- sons of snail distribution rising again in the hilly area is related to the epidemic situation in history and complicated environments. The remnant snails were relatively eugenic. However, the rising of distribution and density of the snails could be controlled if the molluscicide treatment is strengthened.