Malignant Catarrhal Fever

Abstract

Malignant catarrhal fever (MCF) is invariably a fatal disease, primarily of ruminants, caused by gammaherpesviruses belonging to the genus Macavirus. At least ten different forms of MCF have been identified; two are very similar and well-known forms of MCF, i.e. wildebeest-derived MCF and sheep-associated MCF. These two forms are clinico-pathologically almost indistinguishable, but are epidemiologically and aetiologically different. The reservoir hosts, wildebeest and sheep are the asymptomatic carriers and spreaders of the disease to the clinically susceptible animals in the families Bovidae, Giraffidae and Cervidae. In susceptible species, the disease has a multisystemic clinical syndrome, the head and eye form being most commonly seen. Histologically, accumulation of lymphocytes in many tissues is characteristic to MCF; however, due to complexities of pathogenesis and epidemiology in various species, clinicians face significant challenges in the diagnosis of the disease. Genomic detection by PCR remains the confirmatory diagnostic test for MCF. The prognosis of the disease is usually grave, and there is no specific treatment of the disease in the susceptible animal. There is no effective vaccine against MCF though attempts to develop one have been long initiated. Therefore, to date, the major step in controlling the disease relies only on the segregation of the susceptible host species from the reservoir hosts.