an acute, often fatal, virus disease of horses and mules transmitted by mosquitoes and characterized by central nervous system disturbances; in the U.S., this disease is typically caused by one of three alphaviruses, and their resulting diseases are designated western equine, eastern equine, and Venezuelan equine encephalomyelitis; these viruses belong to the family Togaviridae and can also cause neurologic disease in humans. SYN: equine encephalitis.
