Center for Infectious Disease Dynamics, Department of Biology, The Pennsylvania State University, University Park, PA, 16802, USA.
Mol Ecol. 2013 Jan;22(1):239-48. doi: 10.1111/mec.12095. Epub 2012 Oct 30.
Parasite transmission is determined by the rate of contact between a susceptible host and an infective stage and susceptibility to infection given an exposure event. Attempts to measure levels of variation in exposure in natural populations can be especially challenging. The level of exposure to a major class of parasites, trophically transmitted parasites, can be estimated by investigating the host's feeding behaviour. Since the parasites rely on the ingestion of infective intermediate hosts for transmission, the potential for exposure to infection is inherently linked to the definitive host's feeding ecology. Here, we combined epidemiological data and molecular analyses (polymerase chain reaction) of the diet of the definitive host, the white-footed mouse (Peromyscus leucopus), to investigate temporal and individual heterogeneities in exposure to infection. Our results show that the consumption of cricket intermediate hosts accounted for much of the variation in infection; mice that had consumed crickets were four times more likely to become infected than animals that tested negative for cricket DNA. In particular, pregnant female hosts were three times more likely to consume crickets, which corresponded to a threefold increase in infection compared with nonpregnant females. Interestingly, males in breeding condition had a higher rate of infection even though breeding males were just as likely to test positive for cricket consumption as nonbreeding males. These results suggest that while heterogeneity in host diet served as a strong predictor of exposure risk, differential susceptibility to infection may also play a key role, particularly among male hosts. By combining PCR analyses with epidemiological data, we revealed temporal variation in exposure through prey consumption and identified potentially important individual heterogeneities in parasite transmission.
寄生虫传播取决于易感宿主与感染阶段之间的接触率以及暴露事件后感染的易感性。尝试测量自然种群中暴露水平的变化可能特别具有挑战性。可以通过调查宿主的摄食行为来估计主要寄生虫类群（营养传播寄生虫）的暴露水平。由于寄生虫依赖于摄入感染性中间宿主来传播，因此暴露于感染的可能性与终宿主的摄食生态学密切相关。在这里，我们将流行病学数据和对终宿主白足鼠（Peromyscus leucopus）饮食的分子分析（聚合酶链反应）相结合，调查了感染暴露的时间和个体异质性。我们的结果表明，食用蟋蟀中间宿主是感染变异的主要原因；摄入蟋蟀的老鼠感染的可能性是未检测到蟋蟀 DNA 的动物的四倍。特别是，怀孕的雌性宿主更有可能食用蟋蟀，这与非怀孕雌性相比，感染的可能性增加了三倍。有趣的是，处于繁殖状态的雄性感染率更高，尽管繁殖雄性与非繁殖雄性一样有可能检测到蟋蟀的摄入。这些结果表明，尽管宿主饮食的异质性是暴露风险的一个强有力的预测因素，但对感染的易感性差异也可能发挥关键作用，尤其是在雄性宿主中。通过将 PCR 分析与流行病学数据相结合，我们通过猎物消耗揭示了暴露的时间变化，并确定了寄生虫传播中潜在的重要个体异质性。
