Bluetongue is an arthropod-borne viral disease of ruminants characterized by congestion of the buccal and nasal mucosa and the coronary tissue of the hooves, stiffness due to muscle degeneration, and, on occasion, edema of the head and neck; congenital abnormalities may occur in the fetuses of animals infected during pregnancy. Bluetongue is caused by a virus that is classified within the Orbivirus genus in the family Reoviridae. Although bluetongue had been observed as a clinical disease in sheep in South Africa in the 19th century, the first detailed clinical descriptions were not published until 1902. There are reports in the US of diseases in deer similar to epizootic hemorrhagic disease dating back to the 19th century, but it was not until 1955 that a virus was isolated during an epizootic in white-tailed deer (Odocoileus virginianus) in New Jersey. Epizootic hemorrhagic disease virus can be isolated directly in cell cultures of baby hamster kidney and other established cell lines.