Department of Preventive Veterinary Medicine, Faculty of Veterinary Science, Universidad de Chile, Santiago, Chile.
Programa de Doctorado en Ciencias Silvoagropecuarias y Veterinarias, Campus Sur Universidad de Chile, Santiago, Chile.
Transbound Emerg Dis. 2021 May;68(3):1601-1614. doi: 10.1111/tbed.13831. Epub 2020 Sep 26.
Although wild birds are considered the main reservoir of the influenza A virus (IAV) in nature, empirical investigations exploring the interaction between the IAV prevalence in these populations and environmental drivers remain scarce. Chile has a coastline of more than 4000 kilometres with hundreds of wetlands, which are important habitats for both resident and inter-hemispheric migratory species. The aim of this study was to characterize the temporal dynamics of IAV in main wetlands in central Chile and to assess the influence of environmental variables on AIV prevalence. For that purpose, four wetlands were studied from September 2015 to June 2018. Fresh faecal samples of wild birds were collected for IAV detection by real-time RT-PCR. Furthermore, a count of wild birds present at the site was performed and environmental variables, such as temperature, rainfall, vegetation coverage (Normalized Difference Vegetation Index (NDVI)) and water body size, were determined. A generalized linear mixed model was built to assess the association between IAV prevalence and explanatory variables. An overall prevalence of 4.28% ± 0.28% was detected with important fluctuations among seasons, being greater during summer (OR = 4.87, 95% CI 2.11 to 11.21) and fall (OR = 2.59, 95% CI 1.12 to 5.97). Prevalence was positively associated with minimum temperature for the month of sampling and negatively associated with water body size measured two months before sampling, and NDVI measured three months before sampling. These results contribute to the understanding of IAV ecological drivers in Chilean wetlands providing important considerations for the global surveillance of IAV.
尽管野生鸟类被认为是自然界中甲型流感病毒（IAV）的主要宿主，但关于这些种群中 IAV 流行率与环境驱动因素之间相互作用的实证研究仍然很少。智利拥有 4000 多公里的海岸线和数百个湿地，这些湿地是常驻和跨半球迁徙物种的重要栖息地。本研究的目的是描述智利中部主要湿地中 IAV 的时间动态，并评估环境变量对 AIV 流行率的影响。为此，我们从 2015 年 9 月至 2018 年 6 月对四个湿地进行了研究。通过实时 RT-PCR 检测，从野生鸟类的新鲜粪便样本中检测到 IAV。此外，还对现场的野生鸟类数量进行了计数，并确定了环境变量，如温度、降雨量、植被覆盖率（归一化差异植被指数（NDVI））和水体大小。建立了广义线性混合模型，以评估 IAV 流行率与解释变量之间的关联。总体流行率为 4.28%±0.28%，各季节之间波动较大，夏季（OR=4.87，95%CI 2.11 至 11.21）和秋季（OR=2.59，95%CI 1.12 至 5.97）较大。流行率与采样月份的最低温度呈正相关，与采样前两个月测量的水体大小和采样前三个月测量的 NDVI 呈负相关。这些结果有助于了解智利湿地中的 IAV 生态驱动因素，为全球 IAV 监测提供了重要考虑因素。
