安徽马鞍山市博望区“有螺无病”成因调查分析

An investigation on the contribution factors of Oncomelania hupensis snail-existent non-endemic areas of schistosomiasis(SENEAS)in Bowang District,Ma'anshan City,Anhui Province

目的探索马鞍山市博望区有钉螺无血吸虫病流行(简称有螺无病)的原因,为制订该地区血吸虫病防治策略提供科学依据。方法在马鞍山市博望区开展人群、家畜病情和钉螺血吸虫感染情况的现场调查。采集上述“有螺无病”区的钉螺标本,随机分为2组,按照钉螺与毛蚴数量比例1∶20和1∶40分别进行日本血吸虫毛蚴人工感染实验,以同样方法感染该市“有螺有病”区钉螺作为对照。感染后将钉螺置于室内常温下饲养90 d,观察“有螺无病”地区和“有螺有病”地区钉螺感染率和死亡情况。结果在“有螺无病”区调查人群568人,调查家畜40头,血吸虫感染率均为0,现场调查钉螺1100只,未发现感染性钉螺。人工感染实验中,“有螺无病”区钉螺1∶20和1∶40组中的感染率均低于“有螺有病”区钉螺,差异有统计学意义(P<0.05)。结论马鞍山市博望区“有螺无病”区钉螺在适宜环境下可以被日本血吸虫毛蚴感染。钉螺易感性较差和没有足够数量的传染源可能是“有螺无病”区形成的主要原因。

Objective To explore the forming cause of the Oncomelania hupensis snail-existent non-endemic areas of schistosomiasis(SENEAS)in Bowang District,Ma'anshan City,and to provide the scientific evidence for schistosomiasis control measures in the area.Methods Field surveys were carried out in SENEAS in Bowang District for the infection rate of population and livestock,and the distribution of Oncomelania snails.In lab investigation,Oncomelania snails collected from SENEAS in Bowang District were randomly divided into two groups.They were exposed to Schistosoma japonicum miracidia and the ratio of snail to miracidia were 1∶20 and 1∶40,respectively.The same measures were used in Oncomelania snails from endemic areas in Huashan District as control groups.All snails were bred at room temperature for 90 days.Snail infection rate were observed and compared.Results In field research,we have investigated 568 people,40 livestock,and 1100 Oncomelania snails in SENEAS.The infection rate of population and livestock were both 0,and no positive snails were found.In lab investigation,the infection rate of snails in SENEAS were significantly lower than those in endemic areas in both 1∶20 group and 1∶40 group.Conclusion In SENEAS in Bowang District,Oncomeania snails can successfully infected by Schistosoma japonicum miracidia.We believed that the main reason of SENEAS is that there were no sufficient amount of infection source imported,and the low susceptibility to Schistosoma japonicum miracidia of local Oncomeania snails.