Avian Influenza

From WikiVet English
Jump to navigation Jump to search



Subtypes

  • H1-15 and N1-9 have all been isolated
  • Highly Pathogenic Avian Influenza (HPAI), caused by H5 and H7 isolates, is also known as Fowl Plague (FP) and is notifiable
    • Chinese poultry are currently the main reservoir for H5N1, not wild birds

Pathogenesis

  • HPAI is defined by:
    • Heamorrhages
    • Diarrhoea
    • Sometimes nervous symptoms
    • Sudden death
  • H5 spread by feces and infected viscera (kidney/spleen are 100X more infectious than feces)
  • H7 and other viruses are carried by 6% of the wild bird population and outbreaks mirror migrating patterns
    • This poses significant risk to free-range flocks

Zoonotic potential

  • A 2003 Dutch outbreak of a pathogenic H7 virus caused widespread conjunctivitis and flu-like symptoms with recovery among poultry workers
  • Rural chinese children became infected with H5N1 via aerosol transmission, which was limited to upper respiratory symptoms and did not show horizontal spread

Control

  • Prevention by proper hygiene and preventing contact with the wild bird population
  • Isolation and cull of infected premises
  • Firebreak cull in the case of uncontrolled spread
  • Vaccination is not currently practiced for the following reasons:
    • An eradication policy prevents it
    • Vaccination favors the evolution of the virus, which might increase its virulence and drift