Escuela de Medicina Veterinaria, Facultad de Ciencias Biológicas, Facultad de Medicina, Facultad de Agronomía e Ingeniería Forestal, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile.
Departamento de Medicina Preventiva Animal, Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Santiago 8330111, Chile.
Viruses. 2023 May 25;15(6):1241. doi: 10.3390/v15061241.
The Lluta River is the northernmost coastal wetland in Chile, representing a unique ecosystem and an important source of water in the extremely arid Atacama Desert. During peak season, the wetland is home to more than 150 species of wild birds and is the first stopover point for many migratory species that arrive in the country along the Pacific migratory route, thereby representing a priority site for avian influenza virus (AIV) surveillance in Chile. The aim of this study was to determine the prevalence of influenza A virus (IAV) in the Lluta River wetland, identify subtype diversity, and evaluate ecological and environmental factors that drive the prevalence at the study site. The wetland was studied and sampled from September 2015 to October 2020. In each visit, fresh fecal 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 (GLMM) was built to assess the association between AIV prevalence and explanatory variables. Influenza positive samples were sequenced, and the host species was determined by barcoding. Of the 4349 samples screened during the study period, overall prevalence in the wetland was 2.07% (95% CI: 1.68 to 2.55) and monthly prevalence of AIV ranged widely from 0% to 8.6%. Several hemagglutinin (HA) and neuraminidase (NA) subtypes were identified, and 10 viruses were isolated and sequenced, including low pathogenic H5, H7, and H9 strains. In addition, several reservoir species were recognized (both migratory and resident birds), including the newly identified host Chilean flamingo (). Regarding environmental variables, prevalence of AIV was positively associated with NDVI (OR = 3.65, < 0.05) and with the abundance of migratory birds (OR = 3.57, < 0.05). These results emphasize the importance of the Lluta wetland as a gateway to Chile for viruses that come from the Northern Hemisphere and contribute to the understanding of AIV ecological drivers.
鲁塔河是智利最北部的沿海湿地，代表了一个独特的生态系统，也是阿塔卡马沙漠极其干旱地区的重要水源。在旺季，湿地栖息着 150 多种野生鸟类，是许多沿太平洋迁徙路线抵达该国的候鸟的第一站，因此是智利监测禽流感病毒 (AIV) 的重点地点。本研究旨在确定智利鲁塔河湿地流感 A 病毒 (IAV) 的流行率，确定亚型多样性，并评估驱动研究点流行率的生态和环境因素。湿地于 2015 年 9 月至 2020 年 10 月进行了研究和采样。在每次访问中，都会采集野生鸟类的新鲜粪便样本，通过实时 RT-PCR 检测 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 (GLMM) 来评估 AIV 流行率与解释变量之间的关联。对阳性样本进行测序，并通过条形码确定宿主物种。在研究期间筛选了 4349 个样本，湿地的总体流行率为 2.07%（95%CI：1.68 至 2.55），IAV 的月流行率范围很广，从 0%至 8.6%。鉴定出了几种血凝素 (HA) 和神经氨酸酶 (NA) 亚型，分离并测序了 10 种病毒，包括低致病性 H5、H7 和 H9 株。此外，还鉴定了几种储存宿主物种（包括迁徙和留鸟），包括新发现的宿主智利火烈鸟（）。关于环境变量，IAV 的流行率与 NDVI（OR = 3.65，<0.05）和候鸟丰度呈正相关（OR = 3.57，<0.05）。这些结果强调了鲁塔湿地作为来自北半球病毒进入智利的门户的重要性，并有助于了解 AIV 的生态驱动因素。
