Avian influenza

"Bird flu" redirects here. For the M.I.A. song, see Bird Flu.
For the H5N1 subtype of avian influenza, see Influenza A virus subtype H5N1.

Influenza (flu)
H1N1 virus
Types
Vaccines
Treatment
Pandemics
Outbreaks
See also

Avian influenza, also known as avian flu or bird flu, is a disease caused by the influenza A virus, which primarily affects birds but can sometimes affect mammals including humans.[1] Wild aquatic birds are the primary host of the influenza A virus, which is enzootic (continually present) in many bird populations.[2][3]

Symptoms of avian influenza vary according to both the strain of virus underlying the infection, and on the species of bird or mammal affected. Classification of a virus strain as either low pathogenic avian influenza (LPAI) or high pathogenic avian influenza (HPAI) is based on the severity of symptoms in domestic chickens and does not predict severity of symptoms in other species.[4] Chickens infected with LPAI display mild symptoms or are asymptomatic, whereas HPAI causes serious breathing difficulties, significant drop in egg production, and sudden death.[5] Domestic poultry may potentially be protected from specific strains of the virus by vaccination.[6]

Humans and other mammals can only become infected with avian influenza after prolonged close contact with infected birds.[7] In mammals including humans, infection with avian influenza (whether LPAI or HPAI) is rare. Symptoms of infection vary from mild to severe, including fever, diarrhea, and cough.[8]

Influenza A virus is shed in the saliva, mucus, and feces of infected birds; other infected animals may shed bird flu viruses in respiratory secretions and other body fluids (e.g., cow milk).[9] The virus can spread rapidly through poultry flocks and among wild birds.[9] A particularly virulent strain, influenza A virus subtype H5N1 (A/H5N1) has the potential to decimate domesticated poultry stocks and an estimated half a billion farmed birds have been slaughtered in efforts to contain the virus.[10]

  1. ^ "Avian Influenza A H5N1 - United Kingdom of Great Britain and Northern Ireland". www.who.int. Retrieved 2024-05-16.
  2. ^ Li YT, Linster M, Mendenhall IH, Su YC, Smith GJ (December 2019). "Avian influenza viruses in humans: lessons from past outbreaks". British Medical Bulletin. 132 (1): 81–95. doi:10.1093/bmb/ldz036. PMC 6992886. PMID 31848585.
  3. ^ Joseph U, Su YC, Vijaykrishna D, Smith GJ (January 2017). "The ecology and adaptive evolution of influenza A interspecies transmission". Influenza and Other Respiratory Viruses. 11 (1): 74–84. doi:10.1111/irv.12412. PMC 5155642. PMID 27426214.
  4. ^ "Avian Influenza in Birds". U.S. Centers for Disease Control and Prevention (CDC). 2022-06-14. Retrieved 2024-05-06.
  5. ^ "Bird flu (avian influenza): how to spot and report it in poultry or other captive birds". Department for Environment, Food & Rural Affairs and Animal and Plant Health Agency. 2022-12-13. Retrieved 2024-05-06.
  6. ^ "Vaccination of poultry against highly pathogenic avian influenza – Available vaccines and vaccination strategies". www.efsa.europa.eu. 2023-10-10. Retrieved 2024-05-09.
  7. ^ "Influenza Type A Viruses". U.S. Centers for Disease Control and Prevention (CDC). 2024-02-01. Retrieved 2024-05-03.
  8. ^ "Avian influenza: guidance, data and analysis". GOV.UK. 2021-11-18. Retrieved 2024-05-09.
  9. ^ a b "Prevention and Antiviral Treatment of Bird Flu Viruses in People". Centers for Disease Control. 2024-04-19.
  10. ^ Bourk I (26 April 2024). "'Unprecedented': How bird flu became an animal pandemic". www.bbc.com. Retrieved 2024-05-08.