Department of Microbiology, University of Massachusetts, Amherst, United States of America.
Institute of Biology Leiden, Leiden University, Leiden, The Netherlands.
Sci Rep. 2020 Jun 24;10(1):10289. doi: 10.1038/s41598-020-67259-0.
Lyme borreliosis (LB) is the archetypal emerging zoonosis and is dependent on transmission by ticks in the genus Ixodes. Understanding the origin, maintenance, and spread of these ticks contributes much to our understanding of the spread of LB and other disease agents borne by these ticks. We collected 1232 Ixodes scapularis ticks from 17 east coast sites ranging from New Hampshire to Florida and used mtDNA, three nuclear genetic loci, and incorporated Bayesian analyses to resolve geographically distinct tick populations and compare their demographic histories. A sparse, stable, and genetically diverse population of ticks in the Southeastern US, that is rarely infected with the agent of LB is genetically distinct from an abundant, expanding, and comparatively uniform population in the Northeast, where epidemic LB now constitutes the most important vector borne disease in the United States. The contrasting geography and demography of tick populations, interpreted in the context of the geological history of the region, suggests that during the last glacial period such ticks occupied distinct refugia, with only the northern-most site of refuge giving rise to those ticks and pathogens now fueling the epidemic.
莱姆病（LB）是典型的新兴人畜共患病，依赖于硬蜱属（Ixodes）的蜱传播。了解这些蜱的起源、维持和传播，有助于我们了解 LB 以及其他由这些蜱传播的疾病的传播。我们从新罕布什尔州到佛罗里达州的 17 个东海岸地点收集了 1232 只肩突硬蜱，并使用 mtDNA、三个核基因座和贝叶斯分析来确定具有地理差异的蜱种群，并比较它们的种群历史。在美国东南部，蜱种群稀疏、稳定且遗传多样，很少感染 LB 病原体，与东北部大量、扩张且相对均匀的种群不同，目前 LB 是美国最重要的虫媒传染病。在该地区地质历史的背景下，蜱种群的地理和人口统计学差异表明，在上一个冰河时期，这些蜱占据了不同的避难所，只有最北部的避难所产生了现在引发疫情的蜱和病原体。
