河南省永城市恙虫病自然疫源地调查研究

An investigation of natural focus of scrub typhus in Yongcheng,Henan province, China

目的通过调查河南省永城市农村鼠类及其体表寄生恙螨构成和鼠类恙虫病东方体感染率,为该地传染病防控提供科学依据。方法于2017年10月选择永城市不同地点、生境,用鼠夹法捕获鼠类并收集其体表寄生虫,使用巢式PCR检测恙虫病东方体核酸。计算鼠密度及其体表携带恙螨率、恙螨指数和病原体感染率。结果共捕获鼠类110只,捕获率为12.21%,黑线姬鼠占90.00%。从鼠类体表检获恙螨1 249只,河岸林带、湿地和山区林地等生境鼠类带恙螨率和恙螨指数均较高。小板纤恙螨占96.86%,是当地优势螨种,主要寄生在黑线姬鼠体表。鼠类病原学检测阳性率为10.48%,黑线姬鼠、褐家鼠和小家鼠均有阳性。该地恙虫病东方体属于Kawasaki分子型。结论调查证实永城市存在鼠间恙虫病疫源地,与周边地区恙虫病疫源地具有相同的宿主和媒介。

Objective To investigate the species compositions of rodents and the chigger mites on their body surface and the infection rate of Orientia tsutsugamushi in rodents in Yongcheng,Henan province,China,and to provide a scientific basis for the prevention and control of scrub typhus in Yongcheng.Methods Rat traps were used to capture rodents and to collect ectoparasites from the body surface of rodents in different survey sites and different habitats in Yongcheng in October 2017.Nested PCR was used to detect nucleic acid of O.tsutsugamushi.The rodent density,chigger infestation rate,chigger index,and pathogen infection rate were calculated.Results A total of 110 rodents were captured with a capture rate of 12.21%.Apodemus agrarius accounted for 90.00%.A total of 1 249 chigger mites were collected from rodents.The chigger infestation rate and chigger index were relatively high in the forest along the riverbank,wetland,and mountain forest.Leptotrombidium scutellare(96.86%)was the dominant chigger mite species,which was mainly parasitic on the body surface of A.agrarius.The O.tsutsugamushi positive rate of rodent was 10.48%.Apodemus agrarius,Rattus norvegicus,and Mus musculus were detected O.tsutsugamushi positive with nPCR.Orientia tsutsugamushi in Yongcheng belonged to Kawasaki molecular type.Conclusion This study confirms that there are some epidemic foci of scrub typhus with host rodents in Yongcheng,which have the same hosts and vectors as the surrounding epidemic foci of scrub typhus.