Epidemiology of bovine malignant catarrhal fevers, a review.

The mode of transmission of malignant catarrhal fever virus (MCFV) from wildebeest to cattle has been obscure for some time. Recent studies on the virus shedding patterns of wildebeest have revealed that MCFV occur in nasal and ocular secretions of young wildebeest in a stable, cell-free state. Such cell-free virus is not found in the secretions of MCFV infected cattle. The findings indicate that MCFV is transmitted from wildebeest to cattle as cell-free virus shed in the secretions of young wildebeest calves and may explain the non-contagious nature of the disease in cattle. The mode of transmission of sheep-associated MCF has not been determined because the causative agent of this condition has not been isolated from either carrier sheep or sick cattle.