Transmission of West Nile and five other temperate mosquito-borne viruses peaks at temperatures between 23-26ºC

The temperature-dependence of many important mosquito-borne diseases has never been quantified. These relationships are critical for understanding current distributions and predicting future shifts from climate change. We used trait-based models to characterize temperature-dependent transmission of 10 vector–pathogen pairs of mosquitoes (Culex pipiens, Cx. quinquefascsiatus, Cx. tarsalis, and others) and viruses (West Nile, Eastern and Western Equine Encephalitis, St. Louis Encephalitis, Sindbis, and Rift Valley Fever viruses), most with substantial transmission in temperate regions. Transmission is optimized at intermediate temperatures (23–26ºC) and often has wider thermal breadths (due to cooler lower thermal limits) compared to pathogens with predominately tropical distributions (in previous studies). The incidence of human West Nile virus cases across US counties responded unimodally to average summer temperature and peaked at 24ºC, matching model-predicted optima (24–25ºC). Climate warming will likely shift transmission of these diseases, increasing it in cooler locations while decreasing it in warmer locations.

Methods
Mosquito and virus trait data were digitized from previously published papers (see eLife publication for full citations). Encephalitis case data were obtained from the CDC website.

诸多重要蚊媒传染病的温度依赖性尚未得到量化表征。此类关联对于解析当前疾病分布格局、预测气候变化引发的未来传播位移至关重要。本研究依托基于性状的模型，对10组媒介-病原体组合的温度依赖性传播特征进行刻画，涉及的蚊虫包括尖音库蚊（Culex pipiens）、致倦库蚊（Cx. quinquefascsiatus）、环跗库蚊（Cx. tarsalis）等，病毒则涵盖西尼罗河病毒（West Nile）、东部马脑炎病毒、西部马脑炎病毒、圣路易斯脑炎病毒、辛德毕斯病毒以及裂谷热病毒，其中多数病原体在温带区域具备显著传播能力。该类传播过程在中等温度区间（23–26℃）达到最优，且相较于既往研究中以热带分布为主的病原体，往往具备更宽的热幅宽（thermal breadth），这一特性源于更低的临界低温阈值。美国各县级行政区的人类西尼罗河病毒感染病例发病率，随夏季平均气温呈现单峰响应模式，并在24℃时达到峰值，与模型预测的最优温度区间（24–25℃）完全吻合。气候变暖或将推动此类疾病的传播格局发生位移：在较为凉爽的区域，传播风险将有所升高，而在较为温暖的区域则会出现下降。

研究方法
蚊虫与病毒的性状数据均从已发表文献中数字化提取（完整引用信息详见该eLife刊发论文）。脑炎病例数据源自美国疾病控制与预防中心（CDC）官网。