In the past 15 years, few equine diseases have stimulated more interest or gained greater international notoriety than EVA. The disease was thrust into the limelight of industry attention following a 1984 epidemic on a large number of Thoroughbred breeding farms in Kentucky. No outbreaks of EVA had previously been reported in Thoroughbreds in North America. Few equine diseases have been the subject of more misinformation or misperception than EVA. It is an acute, contagious viral disease known to affect horses and other members of the equid family only. EVA is not transmissible to humans or other domestic species. Like influenza and rhinopneumonitis, it is considered primarily a viral infection of the equine respiratory tract.