Parasites can harm hosts and influence populations, communities, and ecosystems. However, parasites are reciprocally affected by population- and community-level dynamics. Understanding feedbacks between infection dynamics and larger-scale epidemiological and ecological processes could improve predictions and reveal novel control methods. We evaluated how exploitative resource competition among hosts, a fundamental aspect of population biology, influences within-host infection dynamics of the widespread human parasite Schistosoma mansoni in its intermediate host, Biomphalaria glabrata. We added size-dependent consumption of shared resources to a parameterized bioenergetics model to predict a priori the growth, parasite production, and survival of an infected focal host coexisting with an uninfected conspecific competitor in an experiment that varied competitor size. The model quantitatively anticipated that competitors disrupt growth and parasite production and that these effects increase with competitor size. Fitting the model to these data improved its match to host survivorship. Thus, resource competition alters infection dynamics, there are strong size asymmetries in these effects, and size-asymmetric resource competition effects on infection dynamics can be accurately predicted by bioenergetics theory. More broadly, this framework can assess parasite transmission and control in other contexts, such as in resource competitive host communities, or in response to eutrophication, food supplementation, or culling.

中文翻译：

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蜗牛之间大小不对称的竞争破坏了人类传染性曼氏血吸虫尾蚴的生产

寄生虫会伤害宿主并影响种群、社区和生态系统。然而，寄生虫受到人口和社区层面动态的相互影响。了解感染动态与更大规模的流行病学和生态过程之间的反馈可以改进预测并揭示新的控制方法。我们评估了宿主之间的资源利用竞争（种群生物学的一个基本方面）如何影响广泛的人类寄生虫曼氏血吸虫在其中间宿主Biomphalaria glabrata中的宿主内感染动态. 我们将共享资源的大小依赖消耗添加到参数化生物能量学模型中，以先验地预测受感染的焦点宿主与未感染的同种竞争者在不同竞争者大小的实验中的生长、寄生虫产生和生存。该模型定量地预测竞争对手会扰乱生长和寄生虫生产，并且这些影响会随着竞争对手的规模而增加。将模型拟合到这些数据改进了它与宿主存活率的匹配。因此，资源竞争会改变感染动态，这些效应存在强烈的尺寸不对称性，并且尺寸不对称的资源竞争对感染动态的影响可以通过生物能量学理论准确预测。更广泛地说，该框架可以评估其他情况下的寄生虫传播和控制，