Lyme disease is the most prevalent vector-borne disease in the United States, yet critical gaps remain in our understanding of tick and host interactions that shape disease dynamics. Rodents such as deer mice (Peromyscus spp.) and dusky-footed woodrats (Neotoma fuscipes) are key reservoirs for Borrelia burgdorferi, the etiological bacterium of Lyme disease, and can vary greatly in abundance between habitats. The aggregation of Ixodes pacificus, the western black-legged tick, on rodent hosts is often assumed to be constant across various habitats and not dependent on the rodent or predator communities; however, this is rarely tested. The factors that determine tick burdens on key reservoir hosts are important in estimating Lyme disease risk because larger tick burdens can amplify pathogen transmission. This study is the first to empirically measure I. pacificus larval burdens on competent reservoir hosts as a function of community factors such as rodent diversity, predator diversity, and questing tick abundance. Rodents were live trapped at oak woodland sites to collect tick burdens and tissue samples to test for infection with Borrelia burgdorferi sensu lato. We found that N. fuscipes tick burdens were negatively correlated with predator diversity, but positively correlated with questing I. pacificus larvae. In addition, rodent hosts that were infected with B. burgdorferi sensu lato tend to have higher burdens of larval ticks. These results demonstrate that tick burdens can be shaped by variability between individuals, species, and the broader host community with consequences for transmission and prevalence of tick-borne pathogens.

莱姆病是美国最流行的媒介传播疾病，但在我们对影响疾病动态的壁虱和宿主相互作用的理解上，仍存在重大差距。啮齿类动物，例如鹿鼠（Peromyscus spp。）和灰脚wood鼠（Neutoma fuscipes）是莱姆病病原菌Borrelia burgdorferi的重要贮藏库，生境之间的丰度差异很大。太平洋凤仙花的聚集通常认为，啮齿动物宿主上的西部黑脚tick在各种生境中都是恒定的，而不依赖于啮齿动物或捕食者群落；但是，这很少经过测试。确定主要水库宿主tick虫负担的因素在估计莱姆病风险中很重要，因为较大的tick虫负担会放大病原体的传播。这项研究是第一个根据经验来测量感受态水库宿主上的I. pacificus幼虫负担的方法，它是诸如啮齿动物多样性，捕食者多样性和寻求壁虱丰度等社区因素的函数。啮齿动物被活活困在橡树林地，以收集tick虫负担和组织样本，以测试是否感染了伯氏疏螺旋体。我们发现鼻息肉的负担与捕食者的多样性呈负相关，但与搜寻大肠埃希菌幼虫呈正相关。另外，感染了博氏疏螺旋体的啮齿动物宿主往往具有较高的幼虫tick负担。这些结果表明，tick虫的负担可以由个体，物种和更广泛的寄主社区之间的变异性来决定，这会影响-传播的病原体的传播和流行。