Malignant Catarrhal Fever (MCF) is a clinicopathological syndrome which occurs in many ruminant species including domestic cattle, white tailed deer, Greater Kudus, and bison. In Africa MCF is caused by a cell associated herpes virus for which the wildebeest is thought to be a carrier. The etiologic agent is less clearly defined for the european-North American form of MCF. Viruses isolated from animals with MCF in the United States include bovine syncytial virus, herpesvirus, togavirus, and a morbilivirus.