Cary Institute of Ecosystem Studies, Millbrook, New York, 12545, USA.
Department of Fisheries and Wildlife, Oregon State University, Corvallis, Oregon, 97331, USA.
Ecology. 2018 Jul;99(7):1562-1573. doi: 10.1002/ecy.2386. Epub 2018 Jun 11.
Changes to the community ecology of hosts for zoonotic pathogens, particularly rodents, are likely to influence the emergence and prevalence of zoonotic diseases worldwide. However, the complex interactions between abiotic factors, pathogens, vectors, hosts, and both food resources and predators of hosts are difficult to disentangle. Here we (1) use 19 yr of data from six large field plots in southeastern New York to compare the effects of hypothesized drivers of interannual variation in Lyme disease risk, including the abundance of acorns, rodents, and deer, as well as a series of climate variables; and (2) employ landscape epidemiology to explore how variation in predator community structure and forest cover influences spatial variation in the infection prevalence of ticks for the Lyme disease bacterium, Borrelia burgdorferi, and two other important tick-borne pathogens, Anaplasma phagocytophilum and Babesia microti. Acorn-driven increases in the abundance of mice were correlated with a lagged increase in the abundance of questing nymph-stage Ixodes scapularis ticks infected with Lyme disease bacteria. Abundance of white-tailed deer 2 yr prior also correlated with increased density of infected nymphal ticks, although the effect was weak. Density of rodents in the current year was a strong negative predictor of nymph density, apparently because high current abundance of these hosts can remove nymphs from the host-seeking population. Warm, dry spring or winter weather was associated with reduced density of infected nymphs. At the landscape scale, the presence of functionally diverse predator communities or of bobcats, the only obligate carnivore, was associated with reduced infection prevalence of I. scapularis nymphs with all three zoonotic pathogens. In the case of Lyme disease, infection prevalence increased where coyotes were present but smaller predators were displaced or otherwise absent. For all pathogens, infection prevalence was lowest when forest cover within a 1 km radius was high. Taken together, our results suggest that a food web perspective including bottom-up and top-down forcing is needed to understand drivers of tick-borne disease risk, a result that may also apply to other rodent-borne zoonoses. Prevention of exposure based on ecological indicators of heightened risk should help protect public health.
宿主动物(尤其是啮齿类动物)的群落生态发生变化,可能会影响全世界人畜共患病的出现和流行。然而,非生物因素、病原体、媒介、宿主以及宿主的食物资源和捕食者之间的复杂相互作用,很难厘清。在这里,我们(1)利用纽约东南部六个大型野外样地 19 年的数据,比较了莱姆病风险的年度变化的假设驱动因素的影响,包括橡果、啮齿动物和鹿的丰度,以及一系列气候变量;(2)采用景观流行病学来探索捕食者群落结构和森林覆盖的变化如何影响莱姆病细菌、伯氏疏螺旋体和另外两种重要的蜱传病原体,嗜吞噬细胞无形体和微小巴贝斯虫的感染率的空间变化。橡果驱动的老鼠数量增加与莱姆病细菌感染的硬蜱幼虫的数量呈滞后增加相关。前两年白尾鹿的数量也与感染性幼虫的密度增加相关,尽管影响微弱。当年的啮齿动物密度是幼虫密度的一个强烈负预测因子,这显然是因为这些宿主的当前高丰度可以将幼虫从宿主寻找种群中去除。温暖、干燥的春季或冬季天气与感染性幼虫密度降低有关。在景观尺度上,功能多样的捕食者群落的存在或唯一的专性食肉动物山猫与所有三种人畜共患病原体的硬蜱幼虫的感染率降低有关。在莱姆病的情况下,当土狼存在时,感染率增加,但较小的捕食者被取代或不存在。对于所有病原体,当半径 1 公里范围内的森林覆盖率较高时,感染率最低。总的来说,我们的结果表明,需要从食物网的角度考虑包括自上而下和自下而上的强制因素,以了解蜱传疾病风险的驱动因素,这一结果可能也适用于其他啮齿动物传播的人畜共患病。基于风险增加的生态指标进行暴露预防,应该有助于保护公众健康。