Emerg Infect Dis. 2024 Sep;30(9):1834-1840. doi: 10.3201/eid3009.240530.
Western equine encephalitis virus (WEEV) is a mosquitoborne virus that reemerged in December 2023 in Argentina and Uruguay, causing a major outbreak. We investigated the outbreak using epidemiologic, entomological, and genomic analyses, focusing on WEEV circulation near the Argentina‒Uruguay border in Rio Grande do Sul state, Brazil. During November 2023‒April 2024, the outbreak in Argentina and Uruguay resulted in 217 human cases, 12 of which were fatal, and 2,548 equine cases. We determined cases on the basis of laboratory and clinical epidemiologic criteria. We characterized 3 fatal equine cases caused by a novel WEEV lineage identified through a nearly complete coding sequence analysis, which we propose as lineage C. Our findings highlight the importance of continued surveillance and equine vaccination to control future WEEV outbreaks in South America.
西部马脑炎病毒（WEEV）是一种由蚊子传播的病毒，于 2023 年 12 月在阿根廷和乌拉圭重新出现，并引发了一次重大疫情。我们使用流行病学、昆虫学和基因组分析方法对疫情进行了调查，重点关注了巴西南里奥格兰德州阿根廷-乌拉圭边境附近的 WEEV 传播情况。在 2023 年 11 月至 2024 年 4 月期间，阿根廷和乌拉圭的疫情导致 217 例人类病例，其中 12 例死亡，2548 例马病例。我们根据实验室和临床流行病学标准确定了病例。我们对 3 例由通过近乎完整的编码序列分析确定的新型 WEEV 谱系引起的致命马病例进行了特征描述，我们将其提议为谱系 C。我们的研究结果强调了继续进行监测和对马进行疫苗接种以控制南美洲未来的 WEEV 疫情的重要性。
