Department of Entomology and Plant Pathology, 301 Funchess Hall, Auburn University, AL 36849, USA.
Department of Biology, University of Washington, Seattle, WA 98195, USA.
J Med Entomol. 2024 Sep 10;61(5):1251-1260. doi: 10.1093/jme/tjae096.
Similar to other states in the southeastern United States, human cases of tick-borne diseases in Alabama have risen steadily over the last 2 decades. Nevertheless, limited data have been published on ticks or tick-borne pathogen (TBP) distributions since the 1990s. To better understand the risk of tick and TBP exposure in eastern central Alabama, ticks were sampled repeatedly across 8 sites associated with recreational use during May and June of 2015 to characterize tick density and diversity. Although habitats were similar across sites, tick density varied among locations. Seven species were collected, but 97.7% of 1,310 samples were the lone star tick, Amblyomma americanum (L.), the primary vector of ehrlichial agents and the tick species most commonly linked to alpha-gal syndrome and southern tick-associated rash illness. To investigate pathogen prevalence among sites, we tested A. americanum by a multiplex qPCR assay for 5 bacterial species, including 3 Ehrlichia spp. and 2 Rickettsia spp. None of the specimens tested positive for Panola Mountain Ehrlichia or Rickettsia parkeri. However, causative agents of human ehrlichiosis, Ehrlichia chaffeensis and Ehrlichia ewingii, occurred at half of the locations with, respectively, 0.27% and 0.45% of A. americanum infected on average. In contrast, Rickettsia amblyommatis, a tick endosymbiont suspected to be nonpathogenic, was found in 54.5% of the 1119 A. americanum tested. Despite low infection rates of Ehrlichia spp. in A. americanum, high encounter rates with this species in recreational deciduous woodlands suggest a moderate risk of tick bite and a low-to-moderate risk of TBP exposure in late spring.
与美国东南部的其他州类似，阿拉巴马州的蜱传疾病人类病例在过去 20 年中稳步上升。然而，自 20 世纪 90 年代以来，有关蜱虫或蜱传病原体（TBP）分布的资料有限。为了更好地了解阿拉巴马州中东部地区蜱虫和 TBP 暴露的风险，我们于 2015 年 5 月至 6 月在与娱乐活动相关的 8 个地点反复采集蜱虫样本，以描述蜱虫密度和多样性。尽管各地点的生境相似，但蜱虫密度在不同地点有所不同。共采集到 7 种蜱虫，但 1310 个样本中有 97.7%为孤星蜱，即主要的埃立克体和致炎螺旋体的载体，也是与 alpha-gal 综合征和南方 tick-associated rash illness 最相关的蜱种。为了调查各地点的病原体流行情况，我们用多重 qPCR 法检测了 A. americanum 携带的 5 种细菌病原体，包括 3 种埃立克体和 2 种立克次体。没有一个标本对 Panola Mountain Ehrlichia 或 Rickettsia parkeri 呈阳性。然而，人埃立克体病的病原体，Ehrlichia chaffeensis 和 Ehrlichia ewingii，在一半的地点出现，平均有 0.27%和 0.45%的 A. americanum 感染。相比之下，Rickettsia amblyommatis，一种被怀疑为非致病性的 tick 内共生体，在 1119 只 A. americanum 中被发现的比例为 54.5%。尽管 A. americanum 中埃立克体的感染率较低，但在娱乐性落叶林地中与该物种的高接触率表明，在春末，蜱叮咬的风险中等，TBP 暴露的风险低至中等。
