On Dec. 28, 2023, the International Health Regulations National Focal Point (IHR NFP) of Argentina notified the World Health Organization (WHO) of a human case of Western Equine Encephalitis (WEE) infection. This is the first confirmed human case reported after more than two decades, since the last reported human cases in Argentina occurred in 1982/1983 and 1996.

WEE is a rare mosquito-borne viral disease that affects equines and humans. Most human cases are associated with epidemics in birds or horses.