Western Equine Encephalitis (WEE) Disease Guidelines

Western Equine Encephalitis (WEE) is an arbovirus (arthropod-borne virus) of potential significance to the equine population. WEE, along with Eastern Equine Encephalitis and Venezuelan Equine Encephalitis, is an alphavirus in the family Togaviridae.

In the United States, cases have principally occurred in the western US and very infrequently in parts of the Midwest. While large equine outbreaks have occurred historically, no equine cases have been reported in the US since 1999. The most important mosquito vector of this disease is Culex tarsalis. 

Note: WEE, just like EEE, is a reportable disease; consult your State Animal Health Official when disease is confirmed.