Difference between revisions of "Bovine Respiratory Syncytial Virus"

From WikiVet English
Jump to navigation Jump to search
Line 8: Line 8:
 
*Replicates in nasal epithelium -> throughout upper respiratory tract -> bronchial tree
 
*Replicates in nasal epithelium -> throughout upper respiratory tract -> bronchial tree
 
*Syncytia form -> shed into bronchioles
 
*Syncytia form -> shed into bronchioles
*Complications include [[Lungs Ventilation - Pathology#Emphysema|emphysema]] and [[Lungs Circulatory - Pathology#Pulmonary oedema|oedema]], drop in milk yield in adult cattle
+
*Complications include [[Lungs Ventilation - Pathology#Emphysema|emphysema]] and [[Pulmonary Oedema|oedema]], drop in milk yield in adult cattle
  
 
====Epidemiology====
 
====Epidemiology====

Revision as of 17:16, 19 February 2011



(BRSV)

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 husbandry 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


  • Causative agent Respiratory syncytial virus (RSV), synonym: bovine RSV (BRSV)
  • Outbreaks of RSV associated disease usually occur associated with winter housing
  • Gross pathology in severe cases
    • Cranioventral atelectasis and consolidation
    • Interstitial emphysema
      • More prominent in the caudal lung lobes
      • Results from bronchoconstriction which results in airway obstruction - this constriction is thought to arise from mast cell degranulation and histamine release
  • Histologically
    • Acute bronchiolitis, characteristic of the bronchiolar response is the formation of syncytial giant cells (formed by proliferating bronchiolar epithelial cells which may contain intracytoplasmic inclusion bodies), alveolar epithelium sometimes affected
    • Obstruction of bronchioles by exudate - these may later become obliterated by the fibrous tissue of organisation
  • May contribute to Enzootic pneumonia of calves