A cross-sectional study was conducted to assess the circulation and risk factors associated with West Nile virus (WNV) exposure in equine and wild bird populations following the largest epidemic outbreak ever reported in Spain. A total of 305 equids and 171 wild birds were sampled between November 2020 and June 2021. IgG antibodies against flaviviruses were detected by blocking enzyme-linked immunosorbent assay (bELISA) in 44.9% (109/243) and 87.1% (54/62) of unvaccinated and vaccinated equids, respectively. The individual seroprevalence in unvaccinated individuals (calculated on animals seropositive by both bELISA and virus microneutralization test [VNT]) was 38.3% (95%CI: 33.1–43.4). No IgM antibodies were detected in animals tested (0/243; 0.0%; 95%CI: 0.0–1.5) by capture-ELISA. The main risk factors associated with WNV exposure in equids were age (adult and geriatric), breed (crossbred) and the absence of a disinsection programme on the facilities. In wild birds, IgG antibodies against flaviviruses were found in 32.7% (56/171; 95%CI: 26.8–38.6) using bELISA, giving an individual WNV seroprevalence of 19.3% (95%CI: 14.3–24.3) after VNT. Seropositivity was found in 37.8% of the 37 species analysed. Species group (raptors), age (>1-year old) and size (large) were the main risk factors related to WNV seropositivity in wild birds. Our results indicate high exposure and widespread distribution of WNV in equid and wild bird populations in Spain after the epidemic outbreak in 2020. The present study highlights the need to continue and improve active surveillance programmes for the detection of WNV in Spain, particularly in those areas at greatest risk of virus circulation.

中文翻译：

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2020 年疫情爆发后西班牙马和野生鸟类种群中西尼罗河病毒的高暴露度

进行了一项横断面研究，以评估在西班牙有史以来最大规模的流行病爆发后，马和野鸟种群中与西尼罗河病毒 (WNV) 接触相关的循环和风险因素。2020 年 11 月至 2021 年 6 月期间，共对 305 只马和 171 只野生鸟类进行了采样。通过阻断酶联免疫吸附试验 (bELISA) 在 44.9% (109/243) 和 87.1% (54/62) 中检测到针对黄病毒的 IgG 抗体分别是未接种疫苗和接种疫苗的马匹。未接种疫苗个体的个体血清阳性率（通过 bELISA 和病毒微量中和试验 [VNT] 对动物血清反应阳性计算）为 38.3%（95%CI：33.1–43.4）。通过捕获-ELISA 在测试的动物中未检测到 IgM 抗体（0/243；0.0%；95%CI：0.0–1.5）。与马科动物接触西尼罗河病毒相关的主要风险因素是年龄（成年和老年）、品种（杂交种）和设施中缺乏杀虫计划。在野生鸟类中，使用 bELISA 发现针对黄病毒的 IgG 抗体占 32.7%（56/171；95%CI：26.8–38.6），在 VNT 后个体 WNV 血清阳性率为 19.3%（95%CI：14.3–24.3）。在分析的 37 个物种中，有 37.8% 发现血清阳性。物种组（猛禽）、年龄（>1 岁）和体型（大型）是与野生鸟类 WNV 血清阳性相关的主要危险因素。我们的结果表明，在 2020 年流行病爆发后，西尼罗河病毒在西班牙的马和野生鸟类种群中高度暴露和广泛分布。本研究强调需要继续和改进在西班牙检测西尼罗河病毒的主动监测计划，