BOVINE MALIGNANT CATARRH/ MALIGNANT CATARRHAL FEVER

This is an almost invariably fatal disease in cattle characterized by fever (high body temperature), weakness, keratitis, dejection, profuse ocular and nasal discharges and encrustation, drooling of saliva, photophobia, erosion and diphtheresis of mucous membranes, generalized lymphoadenopathy, skin lesions and occasional cystitis and nervous involvement. The pathological lesions which affect all organs and tissues are cellular infiltration, necrotizing vasculitis and superficial necrosis of epithelial and mucous surfaces. The pathogenesis of the disease is unknown. In certain parts of East, Central and South Africa, the disease arises due to cattle acquiring infection from clinically normal wilder beast. The causal agent in these areas is the herpes virus. In other parts of Africa and elsewhere in the world, the etiology has not yet been established. The reservoir host in other areas is the sheep but the evidence is not conclusive. The diagnosis is based on its clinical signs and pathological features. Occasionally, transmission may help to confirm the disease.

Clinical signs 
Disease is almost invariably fatal. They are as follows:
Enlargement of superficial lymphnodes
Lethargy and anorexia
High fever around 106oF
Ocular and nasal discharges
Signs of oral discomfort
Skin lesions
Progressive panolphthalmitis
Petechiation
Congestion and small erosions in the mouth
Widespread oral necrosis and diphtheresis
Photophobia.
Pathology
On post-mortem, widespread congestion, exudation, erosion and necrosis and diphtheresis are present.
Occasionally, small vesicles will appear. Erosions in esophagus is present. Respiratory tract is involved with pneumonia ( a lung infection in which air sac is filled with pus). Haemorrhagic cystitis occurs.
Histopathology
Cellular infiltration around blood vessels, lymphoid cells, macrophages and plasma cells are present. The lymphnodes are edematous and congested. Vascular lesions consist of severe necrotizing vasculitis.  The corneal opacity is due to interstitial and small corneal ulcer which may appear sometimes. Pus in the eye (Hypopion) may be found. There is diffused encephalitis characterized by marked perivascular mononuclear and polymorphonuclear cellular accumulations. It is a constant finding. Similar changes may be found in spinal cord.
Differential diagnosis 
Infectious bovine rhinotracheitis
Bovine viral diarrhea
Foot and mouth disease
Acute enteritis through poisoning
Parasitic infestation/salmonellosis
At post-mortem, trypanosomosis and theleriosis may present pathological lesions similar to rinderpest.

Prevention

Good animal husbandry.

Vaccination.