Mwamuye Micky M, Kariuki Edward, Omondi David, Kabii James, Odongo David, Masiga Daniel, Villinger Jandouwe
International Centre of Insect Physiology and Ecology (icipe), P.O. Box 30772-00100, Nairobi, Kenya; School of Biological Sciences, University of Nairobi, P.O. Box 30197-00100, Nairobi, Kenya.
Department of Veterinary and Capture Services, Kenya Wildlife Service, P.O. Box 40241-00100, Nairobi, Kenya.
Ticks Tick Borne Dis. 2017 Feb;8(2):208-218. doi: 10.1016/j.ttbdis.2016.09.002. Epub 2016 Sep 5.
Ticks are important vectors of emerging and re-emerging zoonoses, the majority of which originate from wildlife. In recent times, this has become a global public health concern that necessitates surveillance of both known and unknown tick-borne pathogens likely to be future disease threats, as well as their tick vectors. We carried out a survey of the diversity of ticks and tick-borne pathogens in Kenya's Shimba Hills National Reserve (SHNR), an area with intensified human-livestock-wildlife interactions, where we collected 4297 questing ticks (209 adult ticks, 586 nymphs and 3502 larvae). We identified four tick species of two genera (Amblyomma eburneum, Amblyomma tholloni, Rhipicephalus maculatus and a novel Rhipicephalus sp.) based on both morphological characteristics and molecular analysis of 16S rRNA, internal transcribed spacer 2 (ITS 2) and cytochrome oxidase subunit 1 (CO1) genes. We pooled the ticks (3-8 adults, 8-15 nymphs or 30 larvae) depending on species and life-cycle stages, and screened for bacterial, arboviral and protozoal pathogens using PCR with high-resolution melting analysis and sequencing of unique melt profiles. We report the first molecular detection of Anaplasma phagocytophilum, a novel Rickettsia-like and Ehrlichia-like species, in Rh. maculatus ticks. We also detected Ehrlichia chaffeensis, Coxiella sp., Rickettsia africae and Theileria velifera in Am. eburneum ticks for the first time. Our findings demonstrate previously unidentified tick-pathogen relationships and a unique tick diversity in the SHNR that may contribute to livestock, and possibly human, morbidity in the region. This study highlights the importance of routine surveillance in similar areas to elucidate disease transmission dynamics, as a critical component to inform the development of better tick-borne disease diagnosis, prevention and control measures.
蜱虫是新出现和再度出现的人畜共患病的重要传播媒介，其中大多数起源于野生动物。近年来，这已成为一个全球公共卫生问题，需要对已知和未知的可能成为未来疾病威胁的蜱传病原体及其蜱虫媒介进行监测。我们对肯尼亚的希姆巴山国家保护区（SHNR）的蜱虫和蜱传病原体多样性进行了调查，该地区人类、牲畜和野生动物的互动日益频繁，我们在那里采集了4297只伺机蜱虫（209只成虫、586只若虫和3502只幼虫）。基于形态特征以及对16S rRNA、内部转录间隔区2（ITS 2）和细胞色素氧化酶亚基1（CO1）基因的分子分析，我们鉴定出了两个属的四种蜱虫（埃氏钝眼蜱、托氏钝眼蜱、斑点璃眼蜱和一种新的璃眼蜱属蜱虫）。我们根据物种和生命周期阶段将蜱虫汇集在一起（3 - 8只成虫、8 - 15只若虫或30只幼虫），并使用具有高分辨率熔解分析的PCR和独特熔解曲线的测序对细菌、虫媒病毒和原生动物病原体进行筛查。我们报告了在斑点璃眼蜱中首次通过分子检测发现嗜吞噬无形体、一种新的立克次氏体样和埃立克体样物种。我们还首次在埃氏钝眼蜱中检测到恰菲埃立克体、柯克斯氏体属、非洲立克次氏体和泰勒虫。我们的研究结果表明，在希姆巴山国家保护区存在以前未被识别的蜱虫 - 病原体关系以及独特的蜱虫多样性，这可能导致该地区的牲畜发病，并可能导致人类发病。这项研究强调了在类似地区进行常规监测以阐明疾病传播动态的重要性，这是为更好地制定蜱传疾病诊断、预防和控制措施提供信息的关键组成部分。
