Malignant catarrhal fever

MALIGNANT CATARRHAL FEVER

Synonyms

  • Bovine malignant catarrh, Snotsiekte

Definition

  • It is an acute highly fatal infectious disease of cattle characterized by catarrhal and mucopurulent inflammation of eyes and nostrils, erosions of nasal mucosa rapid progressive emaciation and enlargement of lymphnodes, corneal opacity and nervous symptoms

Etiology

  • Gamma – Herpes virus (lymphotrophic)

Susceptibility

  • Deer, wild ruminants and cattle

Incidence

  • World wide. Also reported in India

Transmission

  • In Africa, virus is carried by wild beast which acts as source of infection for cattle
  • In US – sheep carry the virus and transmits to cattle
  • Not transmissible between infected cattle

Pathogenesis

  • Not known clearly, However, the virus affects variety of organs and produce lesions. But the virus are lymphotropic in nature
  • Lymphotrophic nature of virus; virus is associated with lymphocytes; no free virus is detectable in tissues of cattle
  • Main pathological features are lymphocytic proloiferation and infiltratio witnh vasculitis

Clinical signs

  • High fever 106˚ - 107˚ F
  • Catarrhal conjunctivitis and rhinitis
  • Mucopurulent discharge from eyes and nostrils
  • Exudate flows from eyes and nostrils and soon dries and sticks
  • Eyes are sensitive to light
  • Corneal opacity
  • Emaciation
  • Erosions in skin of muzzle, roof of mouth and cheeks
  • Diarrhoea
  • Nervous signs in later stages
  • In mild disease skin lesions like thickening and peeling of skin in axilla, perineum and neck are seen
  • Lymphnodes swollen – form small subcutaneous nodules, form a chain around the jugular groove of neck

Gross lesions

  • Lymphnodes are swollen; cut surface is granular
  • Erosions in nasal, oral and pharyngeal mucosa covered by mucopurulent exudate
  • Congestion, oedema and erosions in oesophagus, rumen, reticulum and omasum
  • Erosions and ulceration in abomasum
  • Hyperemia and oedema in small intestine
  • Congestion and oedema of eye
  • Enlarged and mottled liver and kidney
  • Renal cortex contain grey to white foci resembling infarcts
  • Cooked up appearance of brain

Microscopical lesions

  • Lymphnodes
    • Dilation of lymphatic channels, severe oedema and proliferation of reticulo – endothelial cells in the  lymph nodes
  • Blood vessels
    • Perivascular and intramural infiltration of mononuclear cells
    • Medial necrosis and endothelial swelling of arteries and arterioles
    • Oral/nasal epithelium
      • Necrosis and lymphocytic infiltration
    • Kidney
      • Collection of mononuclear cells in the cortex
    • Brain
      • Oedema and lymphocyte infiltration in meninges, perivascular cuffing in medulla, pons, hippocampus, cerebrum, cerebellum & spinal grey matter
      • No inclusion bodies or syncytia is seen

Diagnosis

  • Lymphotrophic nature of virus; virus is associated with lymphocytes; no free virus is detectable in tissues of cattle
  • Main pathological features are lymphocytic proloiferation and infiltration with vasculitis
  • ELISA, serum neutralization test; immunofluorescence test
  • Differential diagnosis from Rinderpest based on prominent intestinal lesions
  • Clinical signs along with lesions
Last modified: Monday, 19 March 2012, 4:30 AM