宿主群落系统发育结构对人畜共患病传播风险的影响及内在机制

Zoonotic diseases have caused huge economic losses due to the impacts on public health, animal husbandry, and wildlife conservation. It has been shown that host community composition (e.g. host diversity) can considerably influence the transmission risk of these infectious diseases. However, the roles of host community phylogenetic structure and the evolutionary relatedness between hosts in determining disease risk remain poorly understood. Moreover, most studies on the diversity-disease relationship focused on the risk of single disease without considering disease richness, making them difficult to predict total disease burden. In this research project, we will analyze the spatio-temporal patterns of highly pathogenic avian influenza, African mammal infectious diseases and avian blood parasites of the Thousand Island Lake region to identify risk factors at different scales (extent). By combining mechanism models simulating pathogen transmission dynamics, we particularly aim to reveal how community phylogenetic structure can influence disease risk (including both the risk of single disease and disease burden). Based on abovementioned studies, we will construct predictive models for the risk of global mammal diseases. We expect this project can facilitate our understanding of the transmission dynamics of multi-host pathogens within communities, and provide reliable guidelines for disease prediction, prevention and control in the context of global change.

人畜共患病严重威胁着人类健康、畜牧业生产和野生动物保护，给人类社会带来了巨大的经济损失。研究表明，宿主群落组成结构（如宿主多样性）能显著影响这些传染病的传播风险。然而，宿主间的亲缘关系和宿主群落系统发育结构对疾病风险的影响仍不明确。另外，以往关于宿主多样性-疾病风险关系的研究多聚焦于单一疾病而未考虑疾病多样性，因此难以揭示宿主多样性和疾病总负荷间的关系。本研究拟以高致病性禽流感、非洲兽类传染病及中国千岛湖鸟类血液寄生虫病为研究对象，通过分析不同尺度（幅度）下疾病风险的时空格局以辨识传染病的风险因子，并利用机理模型模拟病原在群落中的传播动态，旨在揭示群落系统发育结构对疾病风险（包括单一疾病风险和疾病负荷）的作用和内在机制，并在此基础上建立全球哺乳动物传染病风险的预测模型。本项目将有助于深入理解群落中多宿主病原的传播动态和内在机制，并为全球变化背景下人畜共患病的预测和防控提供可靠的理论依据。

群落组成结构能够显著影响病原在群落中的传播及疾病风险，作为表征群落结构的重要指标，群落多样性和传染病风险间的关系（多样性-疾病关系）受到了广泛的关注。然而，前期研究中通常聚焦于群落的物种多样性，少有研究关注群落的系统发育多样性及结构。本项目以不同类型（直接传播型及媒介传播型）的人畜共患病为例，系统研究了群落系统发育多样性和传染病风险间的关系。研究发现，群落系统发育多样性和单一疾病（莱姆病和禽流感）及疾病负担（非洲家畜传染病）均呈显著负相关，表明由亲缘关系较近的物种组成的群落具有较高的病原传播风险。在北美地区莱姆病的研究中还发现景观结构（斑块大小和连通度）不仅能直接影响到莱姆病风险，还能够通过影响群落结构（物种多样性和系统发育多样性）间接影响疾病风险。通过比较欧洲历次高致病性禽流感H5暴发的空间格局，发现水鸟群落结构能够显著地影响禽流感在水鸟中的暴发风险，且其作用在不同暴发期具有一致性，表明在预测模型中纳入水鸟群落因子能够显著地提高模型的预测精度，且能较好地预测未来水鸟中禽流感的暴发风险；同时发现水鸟群落结构对家禽中禽流感风险的影响相对较小。此外，通过绘制全球4466种哺乳动物传染病风险图，揭示了当前疾病暴发热点区域，并对未来热点预期进行了预测，同时发现：由于受到种群数量变化的影响，传染病风险在物种灭绝发生之前就可能会产生较大的变化。这些研究结果不仅极大地拓展了多样性-疾病关系研究的理论框架，为相关研究提供了新思路；同时也能为相关疾病的预测和防控提供一些理论依据。