Bird flu: UK is seeing its largest-ever outbreak

In the UK, more than 150 cases of bird flu have been reported between September and November.

Details:

• This outbreak has led to the death of nearly 100 million poultry birds around the world.
• It is threatening wild bird populations in Europe and the US.
• Threat: 15 species of seabirds have tested positive for HPAI for the first time.
• Deaths have been reported in species like great skuas, which are worrying due to their magnitude and potential to threaten the species’ persistence in the UK.

Avian influenza

• Avian influenza is a highly contagious viral disease that occurs primarily in poultry and wild water birds.
• Avian influenza viruses are either high or low-pathogenic viruses (HPAI and LPAI, respectively).
• The variant depends on the molecular characterization of the virus and its ability to cause disease and mortality in chickens.
  • These mutate rapidly and can combine genetic material from other influenza viruses into their genomes to produce new variants.
• The bird flu spreads through their droppings, contaminating the water bodies they visit.
• Avian influenza can be transmitted from animals to humans in two main ways:
  • Directly from birds or from contaminated environments.
  • Through an intermediate host, such as a pig.

Which strain is affecting the poultry right now?

The H5N1 strain of HPAI:

• It seems to be more infectious and more fatal to poultry.
• It is more persistent in wild bird populations.
• It’s also able to affect a greater diversity of species than previous strains.

Avian flu season:

• Western Europe’s avian flu season starts in the autumn.
• It is when millions of migratory birds from colder climates such as geese, ducks, and swans arrive for the winter.
• Their contact with the domestic poultry population may result in the spread of any pathogens carried by them.

What are the different types of avian influenza?

• There are four types of influenza (flu) viruses: A, B, C, and D.
• Wild aquatic birds, including gulls, terns, shorebirds, and wild waterfowl, such as ducks, geese, and swans are considered reservoirs (hosts) for avian influenza A viruses.
• Subtypes of Influenza A Viruses:
  • Influenza A viruses are divided into subtypes based on two proteins on the surface of the virus: hemagglutinin (HA) and neuraminidase (NA).
  • There are 18 known HA subtypes and 11 known NA subtypes.
  • All known subtypes of influenza A viruses can infect birds, except subtypes A(H17N10) and A(H18N11).

Highly Pathogenic and Low Pathogenic Avian Influenza A Viruses

• Avian influenza A viruses are classified into the following two categories:
  • low pathogenicity avian influenza (LPAI) A viruses: Low pathogenic avian influenza viruses cause either no signs of disease or mild disease in chickens/poultry (such as ruffled feathers and a drop in egg production).
  • highly pathogenic avian influenza (HPAI) A viruses: Highly pathogenic?avian influenza viruses?cause severe disease and high mortality in infected?poultry.?
• Both HPAI and LPAI viruses can spread rapidly through poultry flocks.
• Both LPAI and HPAI A viruses have caused mild to severe illness in infected humans.