Savage Harry M, Godsey Marvin S, Tatman Jayden, Burkhalter Kristen L, Hamm Alexandra, Panella Nicholas A, Ghosh Anuradha, Raghavan Ram K
Arbovirus Diseases Branch, Centers for Disease Control and Prevention, Fort Collins, CO.
College of Veterinary Medicine, Kansas State University, Manhattan, KS.
J Med Entomol. 2018 Oct 25;55(6):1613-1616. doi: 10.1093/jme/tjy103.
In June 2016, we continued surveillance for tick-borne viruses in eastern Kansas following upon a larger surveillance program initiated in 2015 in response to a fatal human case of Bourbon virus (BRBV) (Family Orthomyxoviridae: Genus Thogotovirus). In 4 d, we collected 14,193 ticks representing four species from four sites. Amblyomma americanum (L.) (Acari: Ixodidae) accounted for nearly all ticks collected (n = 14,116, 99.5%), and the only other species identified were Amblyomma maculatum Koch (Acari: Ixodidae), Dermacentor variabilis (Say) (Acari: Ixodidae) and Ixodes scapularis Say (Acari: Ixodidae). All ticks were tested for both BRBV and Heartland virus (Family Bunyaviridae: Genus Phlebovirus) in 964 pools. Five Heartland virus positive tick pools were detected and confirmed by real-time reverse transcription PCR (rRT-PCR), while all pools tested negative for BRBV. Each Heartland positive pool was composed of 25 A. americanum nymphs with positive pools collected at three different sites in Bourbon County. A. americanum is believed to be the primary vector of both Heartland and BRBVs to humans based upon multiple detections of virus in field-collected ticks, its abundance, and its aggressive feeding behavior on mammals including humans. However, it is possible that A. americanum encounters viremic vertebrate hosts of BRBV less frequently than viremic hosts of Heartland virus, or that BRBV is less efficiently passed among ticks by co-feeding, or less efficiently passed vertically from infected female ticks to their offspring resulting in lower field infection rates.
2016年6月，继2015年为应对一例波旁病毒（BRBV，正黏液病毒科：托高土病毒属）致死性人类病例而启动的一项更大规模监测项目之后，我们继续对堪萨斯州东部的蜱传病毒进行监测。在4天时间里，我们从4个地点采集了代表4个物种的14193只蜱。美洲钝眼蜱（蜱螨目：硬蜱科）几乎占所采集蜱的全部（n = 14116，99.5%），鉴定出的其他物种仅有斑点钝眼蜱（蜱螨目：硬蜱科）、变异革蜱（蜱螨目：硬蜱科）和肩突硬蜱（蜱螨目：硬蜱科）。所有蜱被分成964组，检测是否感染BRBV和哈特兰病毒（布尼亚病毒科：白蛉病毒属）。通过实时逆转录聚合酶链反应（rRT-PCR）检测并确认了5组哈特兰病毒阳性蜱，而所有组BRBV检测均为阴性。每组哈特兰病毒阳性样本由25只美洲钝眼蜱若虫组成，阳性样本采集自波旁县的3个不同地点。基于在野外采集的蜱中多次检测到病毒、其数量以及对包括人类在内的哺乳动物的攻击性取食行为，美洲钝眼蜱被认为是哈特兰病毒和BRBV传播给人类的主要媒介。然而，美洲钝眼蜱接触BRBV病毒血症脊椎动物宿主的频率可能低于接触哈特兰病毒宿主的频率，或者BRBV通过共同取食在蜱之间传播的效率较低，或者从受感染雌蜱垂直传播给后代的效率较低，导致野外感染率较低。
