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VIRUSES
PARAMYXOVIRIDAE




Pathogenesis

  • More serious than PI-3
  • Causes [Respiratory Viral Infections - Pathology#Respiratory syncytial virus|respiratory infection]]
  • Replicates in nasal epithelium -> throughout upper respiratory tract -> bronchial tree
  • Syncytia form -> shed into bronchioles
  • Complications include emphysema and oedema, drop in milk yield in adult cattle

Epidemiology

    • Subclinical reinfections are important in spreading disease
    • More than 70% of cattle in the UK have antibodies to BRSV

Diagnosis

  • Diseased lung tissue from dead animals or centrifuged cells from lung lavage
  • Virus is too fragile for cell culture isolation (often inactivated in transport)
  • Antigen detection by immunocytochemistry for intracytoplasmic viral inclusions containing labelled viral protein
  • Serology: 4-fold rise in ELISA antibody in paired serum samples from several animals

Control

  • Improve husbansry as in PI-3
  • Vaccines are available but not effective as need to stimulate cytotoxic T-cells

Secondary Concerns

  • Reference: Bryson, 1999, Update on calf pneumonia, CPD Veterinary Medicine, 1,3, 90-95