Table S1 from Bluetongue virus spread in Europe is a consequence of climatic, landscape and vertebrate host factors as revealed by phylogeographic inference

Spatio-temporal patterns of the spread of infectious diseases are commonly driven by environmental and ecological factors. This is particularly true for vector-borne diseases because vector populations can be strongly affected by host distribution as well as by climatic and landscape variables. Here, we aim to identify environmental drivers for bluetongue virus (BTV), the causative agent of a major vector-borne disease of ruminants that has emerged multiple times in Europe in recent decades. In order to determine the importance of climatic, landscape and host-related factors affecting BTV diffusion across Europe, we fitted different phylogeographic models to a dataset of 113 time-stamped and geo-referenced BTV genomes, representing multiple strains and serotypes. Diffusion models using continuous space revealed that terrestrial habitat below 300 m altitude, wind direction and higher livestock densities were associated with faster BTV movement. Results of discrete phylogeographic analysis involving generalized linear models broadly supported these findings, but varied considerably with the level of spatial partitioning. Contrary to common perception, we found no evidence for average temperature having a positive effect on BTV diffusion, though both methodological and biological reasons could be responsible for this result. Our study provides important insights into the drivers of BTV transmission at the landscape scale that could inform predictive models of viral spread and have implications for designing control strategies.

传染病传播的时空模式通常由环境与生态因素驱动。对于虫媒传染病（vector-borne diseases）而言尤其如此，因为媒介种群极易受到宿主分布、气候与景观变量的影响。本研究旨在识别蓝舌病毒（bluetongue virus, BTV）的环境驱动因子——该病毒是引发反刍动物重大虫媒传染病的病原体，近数十年来在欧洲多次暴发流行。为明确气候、景观及宿主相关因素对BTV在欧洲境内传播扩散的影响程度，我们针对涵盖113个带时间戳与地理参考标记的BTV基因组的数据集，拟合了多种系统发育地理学模型，该数据集覆盖多个毒株与血清型。连续空间扩散模型结果显示，海拔300米以下的陆地生境、风向以及更高的牲畜种群密度与BTV更快的传播速率显著相关。纳入广义线性模型（generalized linear models）的离散系统发育地理学分析结果大体支持上述结论，但随空间划分的精细程度不同呈现出较大差异。与主流认知相悖的是，本研究未发现平均气温对BTV传播存在正向影响的证据，该结果可能源于方法论或生物学层面的多重原因。本研究阐明了景观尺度下BTV传播的驱动因子，相关结论可为病毒传播预测模型的构建提供重要参考，同时对防控策略的制定具有指导意义。