Climate change alters disease risks Climate change appears to be provoking changes in the patterns and intensity of infectious diseases. For example, when conditions are cool, amphibians from warm climates experience greater burdens of infection by chytrid fungus than hosts from cool regions. Cohen et al. undertook a global metanalysis of 383 studies to test whether this “thermal mismatch” hypothesis holds true over the gamut of host-pathogen relationships. The authors combined date and location data with a selection of host and parasite traits and weather data. In the resulting model, fungal disease risk increased sharply under cold abnormalities in warm climates, whereas bacterial disease prevalence increased sharply under warm abnormalities in cool climates. Warming is projected to benefit helminths more than other parasites, and viral infections showed less obvious relationships with climate change. Science, this issue p. eabb1702 Climate change may increase disease risk for many wildlife hosts from cooler climates, in contrast to hosts from warmer climates. INTRODUCTION Infectious disease outbreaks among wildlife have surged in recent decades alongside global climate change. However, the circumstances under which climate change is most likely to promote or inhibit infectious disease remain unknown for several reasons. First, researchers know little about how climate change will alter disease risk across hosts and parasites with diverse life history traits (e.g., host thermal biology, habitat, and parasite transmission mode). Second, not all parasites will be affected by climate change, but it remains unclear how the relative risk of disease caused by bacteria, viruses, fungi, and helminths is changing. Third, impacts of temperature abnormalities and variability, rather than increasing mean temperatures alone, remain largely unexplored. Finally, it is not clear which regions of the globe may become more amenable to disease and which may become less suitable. RATIONALE Recently, the thermal mismatch hypothesis has emerged to predict how infection risk is affected by temperature across climate zones in an amphibian-disease system. This hypothesis suggests that hosts adapted to cooler and warmer climates should be at greatest risk of infection under abnormally warm and cool conditions, respectively, because smaller-bodied parasites are more likely to maintain performance over a wider range of temperatures than larger-bodied hosts but are limited by extreme conditions. However, thermal mismatches may not affect diverse hosts and parasites equally because wildlife host and parasite traits can greatly influence disease outcomes. For example, thermal mismatches might exert an especially strong influence over disease outcomes in ectothermic hosts because their immune responses are highly temperature-dependent. To address this challenge, we examined how disease risk was affected by temperature for diverse wildlife hosts and parasites that vary in ecologically important traits across a worldwide climatic gradient. We amassed a global, spatiotemporal dataset describing parasite prevalence across 7346 wildlife populations and 2021 host-parasite combinations. Further, we compiled long-term climate records at each location and short-term weather records during each survey. Our modeling approach investigated how relationships between parasite prevalence and weather depend on local climate and host and parasite traits. Finally, we projected broad-scale changes in disease risk based on thermal mismatches and ensemble climate change model predictions. RESULTS We found that on average, hosts from cool and warm climates experienced increased disease risk at abnormally warm and cool temperatures, respectively, as predicted by the thermal mismatch hypothesis. This effect was greatest among hosts that are ectothermic and nonmigratory and among systems in which the parasite is directly transmitted (without vectors or intermediate hosts). However, the thermal mismatch effect was similar in terrestrial and freshwater systems. Projections based on climate change models indicate that ectothermic wildlife hosts from temperate and tropical zones may experience sharp increases and moderate reductions in disease risk, respectively, though the magnitude of these changes depends on parasite taxa. Prevalence of helminth parasites increased most in temperate zones, whereas fungal parasite prevalence decreased most in tropical zones. CONCLUSION Cold-adapted hosts may experience increasing disease risk during abnormally warm periods. Meanwhile, the risk to warm-adapted hosts may increase during cool periods and mildly decrease during warm periods. Further, these effects are dependent on the identity and traits of the parasite and the host. Our results highlight the complexity of the influences of climate change on diverse host-parasite dynamics, whereas our broad-scale predictions suggest contrasting impacts of climate change across climate zones and diverse parasites. As climate change accelerates, hosts adapted to cooler or milder climates may suffer increasing risk of infectious disease outbreaks, whereas those adapted to warmer climates could see mild reductions in infectious disease risk. The thermal mismatch hypothesis. Predicted patterns of thermal host and parasite performance in isolation (top, left and right) versus patterns of host-parasite interactions (bottom, left and right). Because smaller organisms generally have broader thermal performance curves in isolation than larger organisms, peak parasite growth on hosts is likely at temperatures at which host performance is poor (arrows in top left and top right; curves in bottom left and bottom right). Cold-adapted hosts (left, top and bottom) and warm-adapted hosts (right, top and bottom) should thus experience maximal parasite growth at relatively warm and cool temperatures, respectively. Shaded areas span intermediate temperatures over which relationships between temperature and parasite performance on host are likely to be approximately linear. Disease outbreaks among wildlife have surged in recent decades alongside climate change, although it remains unclear how climate change alters disease dynamics across different geographic regions. We amassed a global, spatiotemporal dataset describing parasite prevalence across 7346 wildlife populations and 2021 host-parasite combinations, compiling local weather and climate records at each location. We found that hosts from cool and warm climates experienced increased disease risk at abnormally warm and cool temperatures, respectively, as predicted by the thermal mismatch hypothesis. This effect was greatest in ectothermic hosts and similar in terrestrial and freshwater systems. Projections based on climate change models indicate that ectothermic wildlife hosts from temperate and tropical zones may experience sharp increases and moderate reductions in disease risk, respectively, though the magnitude of these changes depends on parasite identity.

中文翻译：

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气候变暖对野生动物疾病风险的不同影响

气候变化改变疾病风险 气候变化似乎正在引起传染病模式和强度的变化。例如，当条件凉爽时，来自温暖气候的两栖动物比来自凉爽地区的宿主承受更大的壶菌感染负担。科恩等人。对 383 项研究进行了全球荟萃分析，以测试这种“热不匹配”假设是否适用于宿主 - 病原体关系的整个范围。作者将日期和位置数据与精选的宿主和寄生虫特征以及天气数据相结合。在由此产生的模型中，在温暖气候的寒冷异常下，真菌疾病的风险急剧增加，而在凉爽气候的温暖异常下，细菌疾病的患病率急剧增加。预计变暖比其他寄生虫更有利于蠕虫，病毒感染与气候变化的关系不太明显。科学，这个问题 p。eabb1702 与来自温暖气候的宿主相比，气候变化可能会增加来自凉爽气候的许多野生动物宿主的疾病风险。引言 近几十年来，随着全球气候变化，野生动物之间的传染病暴发激增。然而，由于多种原因，气候变化最有可能促进或抑制传染病的情况仍然未知。首先，研究人员对气候变化将如何改变具有不同生活史特征（例如，宿主热生物学、栖息地和寄生虫传播模式）的宿主和寄生虫的疾病风险知之甚少。其次，并非所有寄生虫都会受到气候变化的影响，但尚不清楚细菌引起疾病的相对风险如何，病毒、真菌和蠕虫正在发生变化。第三，温度异常和变化的影响，而不是仅仅增加平均温度，在很大程度上仍未得到探索。最后，尚不清楚全球哪些地区可能更容易感染疾病，哪些地区可能变得不太适合。基本原理 最近，出现了热失配假说，以预测两栖动物疾病系统中跨气候区的温度如何影响感染风险。这一假设表明，适应凉爽和温暖气候的宿主应该分别在异常温暖和凉爽的条件下面临最大的感染风险，因为体型较小的寄生虫比体型较大的宿主更有可能在更宽的温度范围内保持性能，但受到极端条件的限制。然而，热不匹配可能不会平等地影响不同的宿主和寄生虫，因为野生动物宿主和寄生虫的特征会极大地影响疾病结果。例如，热失配可能对变温宿主的疾病结果产生特别强烈的影响，因为它们的免疫反应高度依赖于温度。为了应对这一挑战，我们研究了温度如何影响不同野生动物宿主和寄生虫的疾病风险，这些宿主和寄生虫在全球气候梯度中具有不同的生态重要特征。我们积累了一个全球时空数据集，描述了 7346 个野生动物种群和 2021 种宿主-寄生虫组合中的寄生虫流行率。此外，我们在每次调查期间编制了每个地点的长期气候记录和短期天气记录。我们的建模方法调查了寄生虫流行与天气之间的关系如何取决于当地气候以及宿主和寄生虫特征。最后，我们根据热失配和整体气候变化模型预测预测了疾病风险的大范围变化。结果我们发现，平均而言，来自凉爽和温暖气候的宿主分别在异常温暖和凉爽的温度下经历了增加的疾病风险，正如热失配假设所预测的那样。这种影响在变温和非迁徙宿主以及寄生虫直接传播的系统（没有媒介或中间宿主）中最为明显。然而，陆地和淡水系统的热失配效应相似。基于气候变化模型的预测表明，来自温带和热带地区的变温野生动物宿主可能会分别经历疾病风险的急剧增加和适度降低，尽管这些变化的幅度取决于寄生虫分类群。蠕虫寄生虫的流行率在温带地区增加最多，而真菌寄生虫的流行率在热带地区下降最多。结论 在异常温暖的时期，适应寒冷的宿主可能会经历增加的疾病风险。同时，适应温暖宿主的风险在凉爽时期可能会增加，而在温暖时期则略微降低。此外，这些影响取决于寄生虫和宿主的身份和特征。我们的结果强调了气候变化对不同宿主-寄生虫动态影响的复杂性，而我们的大规模预测表明，气候变化对不同气候带和不同寄生虫的影响截然不同。随着气候变化的加速，适应较冷或较温和气候的宿主可能面临越来越大的传染病爆发风险，而那些适应温暖气候的宿主则可能会看到传染病风险略有降低。热失配假说。独立的热宿主和寄生虫性能的预测模式（顶部、左侧和右侧）与宿主 - 寄生虫相互作用的模式（底部、左侧和右侧）。由于较小的生物通常比较大的生物具有更宽的热性能曲线，因此宿主上的寄生虫生长高峰可能出现在宿主性能较差的温度下（左上角和右上角的箭头；左下角和右下角的曲线）。冷适应主机（左，因此，顶部和底部）和适应温暖的宿主（右侧、顶部和底部）应该分别在相对温暖和凉爽的温度下经历最大的寄生虫生长。阴影区域跨越中间温度，在该温度范围内，温度与寄主寄生虫性能之间的关系可能近似线性。近几十年来，随着气候变化，野生动物的疾病暴发激增，尽管尚不清楚气候变化如何改变不同地理区域的疾病动态。我们积累了一个全球时空数据集，描述了 7346 个野生动物种群和 2021 种宿主-寄生虫组合中的寄生虫流行情况，并汇编了每个地点的当地天气和气候记录。我们发现来自凉爽和温暖气候的宿主在异常温暖和凉爽的温度下经历了增加的疾病风险，分别由热失配假设预测。这种影响在变温宿主中最大，在陆地和淡水系统中也类似。基于气候变化模型的预测表明，来自温带和热带地区的变温野生动物宿主可能会分别经历疾病风险的急剧增加和适度降低，尽管这些变化的幅度取决于寄生虫的身份。