U.S. Army Medical Research Directorate-Kenya/Kenya Medical Research Institute, Kisumu, Kenya.
U.S. Army Medical Directorate-Armed Forces Research Institute of Medical Science, Bangkok, Thailand.
J Clin Microbiol. 2018 Nov 27;56(12). doi: 10.1128/JCM.01124-18. Print 2018 Dec.
We present data that concurs with the reported geographical expansion of scrub typhus outside the "Tsutsugamushi Triangle" and addition of as a second species in the genus. Wild rodents were caught in Marigat, Baringo County, Kenya, and ectoparasites, including chiggers, were recovered. Rodent and chigger species were identified by taxonomic features. DNA was extracted from the chiggers and used to amplify and/or sequence the 47-kDa high temperature transmembrane protein (TSA47), the 56-kDa type-specific antigen (TSA56), and the 16S rRNA () genes. The main rodent hosts identified were , sp., and , which accounted for 59.2% of the total collection. Of these, and harbored most of the chiggers that belonged to the and genera. A pool of chiggers from one of was positive for by TSA47 PCR, but did not amplify with the TSA56 primers. On sequencing the 850 bp of the TSA47 gene, the closest phylogenetic relative was , with 97.65% sequence homology compared to 84.63 to 84.76% for 16S rRNA deep sequencing also revealed as the closest phylogenetic relative, with 99.75% sequence homology. These results and the existing immunological and molecular reports are strongly suggestive of the existence of species in Kenya.
我们提供的数据与报道的恙虫病在“恙虫病三角”以外地区的地理扩张一致，并在恙虫病属中增加了 作为第二个种。在肯尼亚巴林戈县的马里加特捕获了野生啮齿动物，并回收了包括恙螨在内的外寄生虫。通过分类特征对啮齿动物和恙螨种类进行了鉴定。从恙螨中提取 DNA，用于扩增和/或测序 47 kDa 高温跨膜蛋白（TSA47）、56 kDa 型特异性抗原（TSA56）和 16S rRNA（）基因。鉴定出的主要啮齿动物宿主为 、 sp.和 ，占总采集量的 59.2%。其中， 和 携带了大部分属于 和 属的恙螨。从 之一的恙螨池中，通过 TSA47 PCR 检测到对 的阳性反应，但 TSA56 引物未扩增。对 TSA47 基因的 850 bp 进行测序后，最接近的系统发育亲缘关系是 ，与 16S rRNA 的序列同源性为 97.65%，而深度测序的 84.63%至 84.76%。深度测序还显示 为最接近的系统发育亲缘关系，序列同源性为 99.75%。这些结果以及现有的免疫学和分子报告强烈表明肯尼亚存在 种。
