Swine Influenza



Subtypes

  • Avian-like H1 and human-like H3 strains vary in virulence

Pathogenesis

  • Necrotising bronchiolitis with catarrhal pus
  • Barking cough
  • Interstitial pneumonia giving consolidation of the lungs and a 'meaty' appearance
  • Often associated with bacteria, mycoplasma or immunosuppressive viruses (such as PRRS)
  • The virus recycles on farms as litters outgrow maternal antibody at 12 weeks of age

Diagnosis

  • Clinical pneumonia is always suspect
  • Serology: retrospective diagnosis by HI

Control

  • Isolation of premises
  • All-in/all-out systems
  • Vaccination is not licensed in the UK


  • Caused by Orthomyxoviridae
  • Rhinitis, may progress to pneumonia
  • Clinical signs: pyrexia, lethargy, skin erythema, anorexia, severe cough and sneezing, dyspnoea, conjunctivitis, pregnant sows may abort
  • Grossly:
  • Histologically:
    • Acute inflammation of mucosa of trachea and bronchi
  • Zoonotic
  • Circumstantial evidence of mutation from human strain
  • Migrating ascarids thought to precipitate the disease, reservoir of infection in earthworms containing infected lungworm larvae