Center for International Health, Ludwig-Maximilians-University, Munich, Germany.
Central Reference Laboratory, Kazakh Scientific Center for Quarantine and Zoonotic Diseases, Almaty, Kazakhstan.
Parasit Vectors. 2019 May 3;12(1):197. doi: 10.1186/s13071-019-3440-9.
Over 60 years ago clinical patterns resembling tick-borne rickettsioses have been described for the first time in Kazakhstan. Since 1995 the incidence of clinical cases of tick-borne rickettsioses in humans seems to be rising but studies on epidemiological data regarding the occurring etiological agents, tick vector species, prevalence and distribution throughout Kazakhstan are still scarce to date. The aim of the study was molecular investigation of ticks for spotted-fever group rickettsiae in the endemic Kyzylorda region and the so far considered as non-endemic Almaty region. A total of 2341 ticks was collected in the two regions in Kazakhstan and sorted in 501 pools: Ixodes persulcatus (243); Dermacentor marginatus (129); Haemaphysalis punctata (104); Hyalomma asiaticum (17); Dermacentor reticulatus (3); and Rhipicephalus turanicus (5). Pools were tested for Rickettsia spp. using real-time PCR. For positive samples multilocus sequence typing (MLST) was performed.
The calculated minimum infection rate (MIR) for rickettsiae in the investigated ticks in Almaty region varied between 0.4-15.1% and 12.6-22.7% in the Kyzylorda region. At least four different Rickettsia species were identified in the two selected regions of Kazakhstan. Two of these are already known to science: Rickettsia raoultii and R. slovaca, the latter being reported for the first time in Almaty region One new form, "Candidatus R. yenbekshikazakhensis", was described by MLST of six gene fragments in Almaty region and one new genotype, "genotype R. talgarensis" was detected using three gene fragments.
Kazakh physicians should be aware of rickettsioses after tick bites in both regions studied. Both, R. raoultii and R. slovaca should be included in the diagnostics. The role for human diseases has further to be investigated for the newly described rickettsiae, "Candidatus R. yenbekshikazakhensis" and "Genotype R. talgarensis".
60 多年前，哈萨克斯坦首次描述了类似于蜱传立克次体病的临床模式。自 1995 年以来，人类蜱传立克次体病的临床病例似乎呈上升趋势，但关于发生的病因、蜱传媒介种类、流行率以及整个哈萨克斯坦的分布情况的流行病学数据研究仍然很少。本研究的目的是对流行的克孜勒奥尔达州和迄今被认为是非流行的阿拉木图地区的 ticks 进行斑点热群立克次体的分子调查。在哈萨克斯坦的两个地区共采集了 2341 只 ticks，并分为 501 个池：Ixodes persulcatus（243）；Dermacentor marginatus（129）；Haemaphysalis punctata（104）；Hyalomma asiaticum（17）；Dermacentor reticulatus（3）；和 Rhipicephalus turanicus（5）。使用实时 PCR 检测池中的 Rickettsia spp。对阳性样本进行多位点序列分型（MLST）。
在阿拉木图地区调查的 ticks 中，rickettsiae 的最低感染率（MIR）计算值在 0.4-15.1%和 12.6-22.7%之间，在克孜勒奥尔达州则在 0.4-15.1%和 12.6-22.7%之间。在哈萨克斯坦的两个选定地区至少鉴定出了四种不同的 Rickettsia 物种。其中两种已经为科学界所熟知：Rickettsia raoultii 和 R. slovaca，后者首次在阿拉木图地区报道。一种新形式，"Candidatus R. yenbekshikazakhensis"，通过 MLST 在阿拉木图地区的六个基因片段进行描述，一种新基因型，"genotype R. talgarensis"，通过三个基因片段检测到。
在研究的两个地区，哈萨克斯坦医生应该意识到 tick 叮咬后的立克次体病。R. raoultii 和 R. slovaca 都应该包括在诊断中。对于新描述的立克次体，"Candidatus R. yenbekshikazakhensis"和"Genotype R. talgarensis"，还需要进一步研究其对人类疾病的作用。
