Malignant Catarrhal Fever

Abstract

Malignant catarrhal fever (MCF) is an almost invariably fatal disease in cattle, characterized by fever, depression, profuse nasal and ocular discharge and encrustation, drooling of saliva, photophobia, keratitis, erosion and diphtheresis of oral membranes, generalized lymphodenopathy, skin lesions and, occasionally, cystitis and central nervous involvement. The pathological features, which affect all organs and tissues are necrotizing vasculitis, marked cellular infiltration and superficial necrosis of both epithelial and mucous surfaces. The pathogenesis of the disease is unknown but it has been suggested that it is a virus-associated lymphoproliferative auto-reactive disease.

In certain parts of east, central and southern Africa, the disease arises as the result of cattle acquiring infection from clinically-normal wildebeests. The causal agent in this situation is a cell-associated, polykaryon-forming herpesvirus (bovid herpesvirus 3). In other parts of Africa and elsewhere in the world, the etiology of MCF has not yet been established. The reservoir host is assumed to be the sheep but there is little definitive evidence to support this view.

Diagnosis of MCF is usually based on its distinctive clinical and pathological features. On occasions (particularly with the wildebeest-derived infections) transmission studies may help to confirm the presence of the disease. The use of virus-isolation techniques is limited to the latter form of MCF. There is no effective treatment for MCF and, at present, prevention depends upon avoidance of contact with known or suspected reservoir hosts.