West Nile virus (WNV) is a mosquito-borne Flavivirus that can affect birds, horses, and humans, and is the only zoonotic Flavivirus that has been identified in six continents. In Brazil, until 2010, there was no evidence of WNV circulation. Recently, the virus was isolated from a horse with encephalitis, and the first human cases were registered in Brazil. Despite that, there is still no information on the enzootic cycle of this virus in birds or wildlife. This study aimed to investigate whether there is evidence of WNV circulation among wild birds from Southern Brazil. For this, we used free-living wild raptors (live-trapped or rescued) as potential sentinels to investigate the presence of WNV antibodies using ELISA and plaque reduction neutralization test (PRNT) assay. In addition, the presence of nucleic acids from Flavivirus family members was investigated. None of the birds sampled presented clinical findings compatible with WNV. Of the 200 serum samples from birds of prey belonging to 21 species, ten (5%) were positive for the presence of WNV antibodies on ELISA testing. The PRNT test did not confirm the ELISA results, but indicated that three birds had possibly been exposed to Saint Louis encephalitis virus (SLEV). All samples were negative for Flavivirus RNA. The results presented here evince the need for permanent surveillance for emerging flaviviruses in Brazil, as well as for a contingency policy in the case of human/animal outbreaks, particularly in high-risk areas.

中文翻译：

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来自巴西的自由放养猛禽的西尼罗河病毒 (WNV) 血清学调查

西尼罗河病毒 (WNV) 是一种由蚊子传播的黄病毒，可影响鸟类、马和人类，是唯一在六大洲发现的人畜共患黄病毒。在巴西，直到 2010 年，才发现有西尼罗河传播的证据。最近，从一匹患有脑炎的马身上分离出该病毒，并在巴西登记了首例人类病例。尽管如此，仍然没有关于这种病毒在鸟类或野生动物中的地方性循环的信息。本研究旨在调查是否有证据表明巴西南部的野生鸟类中存在 WNV 传播。为此，我们使用自由生活的野生猛禽（活捉或获救）作为潜在的哨兵，使用 ELISA 和斑块减少中和试验 (PRNT) 测定来研究 WNV 抗体的存在。此外，研究了来自黄病毒家族成员的核酸的存在。采样的鸟类均未呈现与 WNV 相符的临床发现。在属于 21 个物种的猛禽的 200 份血清样本中，有 10 份（5%）在 ELISA 测试中检测出 WNV 抗体呈阳性。PRNT 测试未证实 ELISA 结果，但表明三只鸟可能已暴露于圣路易斯脑炎病毒 (SLEV)。所有样品的黄病毒 RNA 均为阴性。此处提供的结果表明，需要对巴西新出现的黄病毒进行永久监测，并需要针对人类/动物爆发的应急政策，特别是在高风险地区。在属于 21 个物种的猛禽的 200 份血清样本中，有 10 份（5%）在 ELISA 测试中检测出 WNV 抗体呈阳性。PRNT 测试未证实 ELISA 结果，但表明三只鸟可能已暴露于圣路易斯脑炎病毒 (SLEV)。所有样品的黄病毒 RNA 均为阴性。此处提供的结果表明，需要对巴西新出现的黄病毒进行永久监测，并需要针对人类/动物爆发的应急政策，特别是在高风险地区。在属于 21 个物种的猛禽的 200 份血清样本中，有 10 份（5%）在 ELISA 测试中检测出 WNV 抗体呈阳性。PRNT 测试未证实 ELISA 结果，但表明三只鸟可能已暴露于圣路易斯脑炎病毒 (SLEV)。所有样品的黄病毒 RNA 均为阴性。此处提供的结果表明，需要对巴西新出现的黄病毒进行永久监测，并需要针对人类/动物爆发的应急政策，特别是在高风险地区。