Epizootic hemorrhagic disease (EHD) is one of the most important diseases of deer in North America. The epizootic hemorrhagic disease viruses (EHDV) are widespread in white-tailed deer and periodically cause serious epidemics in wild populations.

Some of these viruses can also cause disease in cattle. In the U.S., EHD in cattle is uncommon, rarely fatal, and usually associated with an epidemic in deer. However, an EHDV serogroup virus called the Ibaraki virus causes serious epidemics in Japan, Korea, and Taiwan that may affect as many as 39,000 cattle. The disease caused by the Ibaraki virus is known as Ibaraki disease; some authorities consider it to be a synonym for epizootic hemorrhagic disease in cattle.