Division of Environmental Health Sciences, School of Public Health, University of Minnesota, 420 Delaware St SE, Minneapolis, MN, 55455, USA.
Metropolitan Mosquito Control District, St. Paul, MN, USA.
Ecohealth. 2023 Sep;20(3):273-285. doi: 10.1007/s10393-023-01656-5. Epub 2023 Nov 21.
Research on the public health significance of Ixodes scapularis ticks in the Midwest seldom focuses on extreme weather conditions that can modulate their population dynamics and ability to transmit pathogenic organisms. In this study, we assessed whether the distributional abundance of I. scapularis immatures is associated with current and time-lagged climatic determinants either directly or indirectly. We analyzed a 20-year longitudinal small mammal live-trapping dataset within a seven-county metropolitan area in Minnesota (1998-2016) using yearly tick counts at each site to assess whether inter- and intra-annual variation in immature I. scapularis counts is associated with climate and land-use conditions. We found that (1) immature I. scapularis ticks infesting mammals expanded southwesterly over the study period, (2) eastern chipmunks, Tamias striatus, supplied a substantial proportion of nymphal blood meals, (3) a suite of climatological variables are demonstrably associated with I. scapularis presence, and abundance across sites, most notably summer vapor pressure deficit, and (4) immature I. scapularis display an affinity for deciduous forests in metro areas. Our results suggest that climatic and land-type conditions may impact host-seeking I. scapularis ticks through numerous mechanistic avenues. These findings extend our understanding of the abiotic factors supporting I. scapularis populations in metro areas of the upper Midwest with strong implications for discerning future tick-borne pathogen risk.
关于中西部硬蜱的公共卫生意义的研究很少关注能够调节其种群动态和传播病原体能力的极端天气条件。在这项研究中，我们评估了硬蜱幼虫的分布丰度是否直接或间接地与当前和时间滞后的气候决定因素有关。我们分析了明尼苏达州一个七县大都市区 20 年的纵向小型哺乳动物活捕数据集（1998-2016 年），每个地点的蜱虫计数每年评估一次，以评估幼虫期硬蜱的数量变化是否与气候和土地利用条件有关。我们发现：（1）在研究期间，感染哺乳动物的硬蜱幼虫向西南方向扩展；（2）东部花栗鼠（Tamias striatus）为若虫血餐提供了相当大的比例；（3）一套气候变量与蜱虫的存在和丰度显著相关，特别是夏季蒸气压亏缺；（4）幼虫期硬蜱对城市地区的落叶林有亲和力。我们的结果表明，气候和土地类型条件可能通过多种机制影响寻找宿主的硬蜱。这些发现扩展了我们对支持中西部上地区城市硬蜱种群的生物因素的理解，对辨别未来蜱传病原体风险具有重要意义。
