云南省景洪市四地溪蟹并殖吸虫感染情况调查

Investigation of the prevalence of Paragonimusinfecting crabs in 4 areas of the City of Jinghong,Yunnan Province

目的了解云南省景洪市自然生态环境保护良好的地区并殖吸虫第二中间宿主溪蟹的种类及自然感染情况,探明并殖吸虫病的流行与自然疫源地的生态环境关系。同时丰富并殖吸虫或并殖吸虫病方面的流行病学资料,为今后制定并殖吸虫病的防治策略提供科学依据。方法从景洪市基诺山、曼赛囡、林宽新寨和补蚌的山涧溪流中采集溪蟹,经分类鉴定后采用组织捣碎过筛水洗沉淀法分离囊蚴,置生物体视镜下检查囊蚴或后尾蚴并分类计数。用常规方法统计不同调查点溪蟹的自然感染率和平均感染度。然后根据囊蚴的大小、囊壁的有无和层数、以及囊内蚴体的形态和排泄囊的特征,初步鉴定并殖吸虫的种属。将经过分类定种的囊蚴或者后尾蚴分别经口饲感染实验终宿主,获取成虫作为虫种的分类鉴定和验证结果。结果四地共采集到278只溪蟹,经鉴定均为景洪溪蟹。其中基诺山捕获溪蟹44只,自然感染率36.37%,平均感染度6.31;曼赛囡141只,自然感染率63.12%,平均感染度7.75;林宽新寨70只,自然感染率27.14%,平均感染度6.42;补蚌23只,自然感染率52.17%,平均感染度7.33。四个调查地点并殖吸虫虫种结构复杂,优势虫种为丰宫并殖吸虫。结论并殖吸虫在景洪市分布广泛,并殖吸虫病的流行与自然疫源地的生态环境关系密切。

Objectives To ascertain species of crabs infected with Paragonimus as second intermediate hosts and the prevalence of natural infection in environmentally protected areas of the City of Jinghong,Yunnan Province in order to determine the relationship between natural foci of paragonimiasis and the environment.To accumulate epidemiological data on Paragonimus and paragonimiasis in Yunnan Province in order to provide a good scientific foundation for prevention of paragonimiasis. Methods Fresh crabs collected from mountain streams in Jinuoshan,Mansainan,Linkuanxinzhai,and Bubeng in the City of Jinghong were identified.Metacercariae were separated using pressure washing and precipitation,and then metacercariae and excysted metacercariae were counted and classified under a biological microscope.Conventional statistical methods were used to determine the natural rate of infection and the average degree of infection in crabs from different study sites.The species of Paragonimus were identified primarily based on the size of the metacercariae,the presence or absence of a cyst wall and the number of layers in that wall,and the shape of the larva and the characteristics of the excretory bladder.Metacercariae and excysted metacercariae that had been identified by species were fed to final hosts to infect those animals.Adult parasites were obtained and the results of classification and identification were verified. Results Two hundred and seventy-eight crabs were collected from four areas,and these crabs were identified as Potamon chinghungense.Forty-four of these crabs were from Jinuoshan,and these crabs had a natural rate of infection of 36.37% and an average degree of infection of 6.31.One hundred and forty-one of these crabs were from Mansainan,and these crabs had a natural rate of infection of 63.12% and an average degree of infection of 7.75.Seventy of these crabs were from Linkuanxinzhai,and these crabs had a natural rate of infection of 27.14%and an average degree of infection of 6.42.Twenty-three of these crabs were from Bubeng,and these crabs had a natural rate of infection of 52.17%and an average degree of infection of 7.33.There was a complex composition of species found at the four study sites,and the predominant species was Paragonimus proliferus. Conclusion Paragonimus is widely distributed in the City of Jinghong.The prevalence of paragonimiasis is closely related to the environment at the foci of natural infection.