云南省永善县恙虫病流行病学调查

目的 对云南省永善县恙虫病开展流行病学调查。方法 应用胶体金免疫试验对发热患者血清进行恙虫病东方体(Orientia tsutsugamsushi)IgG和IgM抗体检测,采用夜夹法诱捕调查地区鼠类,用巢氏PCR方法对鼠脾脏做groEL基因片段扩增和基因序列分析。结果 2015年5-10月在永善县发现恙虫病患者34例,其中实验室确诊病例21例,临床诊断病例13例;主要发病于8月,占总病例数的32.35%;40—49岁年龄组发病最多,占总病例数的32.35%;农民发病数最多,占总病例数的79.41%;有焦痂或溃疡的病例占总病例数的94.12%,其中位于腹股沟最多(占有焦痂或溃疡患者的31.25%);有皮疹的病例占总病例数的50.00%。在捕获的39份黄胸鼠(Rattus flavipectus)脾组织样品中,恙虫病东方体groEL基因片段扩增阳性9份(阳性率23.08%)。groEL基因片段序列进化树分析显示本次检测到的YSP30株与的HSB1、FAR1、UAP4等Saitama型菌株的遗传进化关系最密切, 检测到的其余8株与UT213、UT221、SH205等Karp型菌株的遗传进化关系最密切。结论 血清学和分子生物学方法证实了永善县存在恙虫病疫源地,当地存在Karp和Saitama相关的2种基因型恙虫病东方体。

Investigation on scrub typhus in Yongshan County,Yunnan Province,China

We investigated epidemiological characteristic of scrub typhus in Yongshan County, Yunnan Province, China. The serum samples were collected from the patients with fever for detecting the antibody against Orientia tsutsugamsushi (Ot) by colloidal gold immunoassay assay. Rat traps were used to capture rodents. The spleen tissues of the captured rodents were detected by nested-polymerase chain reaction for rickettsia groEL segment. The groEL segments were sequenced and analyzed the homology with the other known sequences. Thirty-four scrub typhus cases were found in Yongshan County, Yunnan Province from May 2015 to October 2015. Among them, 21 cases were confirmed by laboratory tests and 13 cases were clinical diagnosis diseases. Of these patients, 32.35% of the cases occurred in June. The 32.35% were in the group of the 40-49 year-old, and 79.41% were farmers,94.12% exhibited eschar or skin ulcer(31.25% were observed in groin of these cases), and rash developed in 50%. In 39 spleen tissue samples of Rattus flavipectus, 9 samples showed positive for groEL gene Ot, but groEL gene of Typhus group rickettsia and spotted fever group rickettsia were negative. Sequence analysis showed that YSP30 was closely related to some Saitama related strains of Ot, such as HSB1, FAR1 and UAP4, while the other 8 strains were closely related to some Karp related strains of Ot, such as UT213, UT221 and SH205. It was confirmed that the Yongshan County was the natural foci of scrub typhus by the serological and molecular biological detections. There are Karp and Saitama genotype related Ots in the natural foci.