Equine viral arteritis (EVA) is a disease of horses caused by Alphaarterivirus equid, an RNA virus. It is the only species in the genus Alphaarterivirus, and that is the only genus in the Equarterivirinae subfamily. The virus which causes EVA was first isolated in 1953, but the disease has afflicted equine animals worldwide for centuries. It has been more common in some breeds of horses in the United States, but there is no breed "immunity". In the UK, it is a notifiable disease. There is no known human hazard.