Roy Manojit, Holt Robert D
Department of Zoology, University of Florida, 223 Bartram Hall, PO Box 118525, Gainesville, FL 32611-8525, USA.
Theor Popul Biol. 2008 May;73(3):319-31. doi: 10.1016/j.tpb.2007.12.008. Epub 2008 Jan 1.
The integration of infectious disease epidemiology with community ecology is an active area of research. Recent studies using SI models without acquired immunity have demonstrated that predation can suppress infectious disease levels. The authors recently showed that incorporating immunity (SIR models) can produce a "hump"-shaped relationship between disease prevalence and predation pressure; thus, low to moderate levels of predation can boost prevalence in hosts with acquired immunity. Here we examine the robustness of this pattern to realistic extensions of a basic SIR model, including density-dependent host regulation, predator saturation, interference, frequency-dependent transmission, predator numerical responses, and explicit resource dynamics. A non-monotonic relationship between disease prevalence and predation pressure holds across all these scenarios. With saturation, there can also be complex responses of mean host abundance to increasing predation, as well as bifurcations leading to unstable cycles (epidemics) and pathogen extinction at larger predator numbers. Firm predictions about the relationship between prevalence and predation thus require one to consider the complex interplay of acquired immunity, host regulation, and foraging behavior of the predator.
传染病流行病学与群落生态学的整合是一个活跃的研究领域。最近使用无获得性免疫的SI模型的研究表明，捕食可以抑制传染病水平。作者最近表明，纳入免疫因素（SIR模型）可以在疾病流行率和捕食压力之间产生一种“驼峰”形关系；因此，低到中等水平的捕食可以提高具有获得性免疫的宿主中的流行率。在这里，我们研究了这种模式对基本SIR模型的实际扩展的稳健性，包括密度依赖的宿主调节、捕食者饱和、干扰、频率依赖的传播、捕食者数量反应以及明确的资源动态。在所有这些情况下，疾病流行率和捕食压力之间都存在非单调关系。在饱和情况下，平均宿主丰度对增加的捕食也可能有复杂的反应，以及导致不稳定周期（流行病）和在更大捕食者数量下病原体灭绝的分岔。因此，关于流行率和捕食之间关系的可靠预测需要考虑获得性免疫、宿主调节和捕食者觅食行为的复杂相互作用。
