Epidemic alert: Virology of Avian Influenza virus

Epidemic alert: Virology of Avian Influenza virus

Avian influenza, also known as bird flu, was first detected in China in 1996 in a goose. General virology of Avian Influenza virus refers to an influenza type-A virus subtype of H5A1. Primarily domestic poultry, zoo, and wild birds are victimized by the Avian influenza virus. Recently, WHO reported 889 cases with 463 deaths of humans by Avian flu among 23 countries of the world. The situation turned aggravated when the USA reported human contamination by bird flu in 2024 in Texas and Michigan.

Why influenza virus is so widespread?

The globe has gone through several variants of the influenza virus to date. Four types of influenza viruses have been detected now.  

  • Type-A influenza or genus Alphainfluenzavirus:  Causes seasonal flu almost every year but it is the only type of influenza virus whose subtypes can originate a global pandemic of flu diseases.
  • Type-B influenza or genus Betainfluenzavirus: Like Type-A influenza, Type-B also affects humans and animals for common flu, especially in the winter season.
  • Type-C influenza or genus Gammainfluenzavirus: Over time, mankind has developed immunity against the Type-C influenza virus, still it might lead to little illness to people.
  • Type-D influenza or genus Deltainfluenzavirus: No report of humans affected by D-Type influenza has been reported but it infects cattle and pigs mostly.

Talking about Type-A influenza, H1N1 and H3N1 subtypes are most common among the world population, still, new variants of H5N1 and H7N9 have been introduced in previous decades causing bird flu and Animal flu.

What is the genomic structure and virulence of Avian flu or bird flu?

Simply, a single-stranded RNA virus is responsible for bird flu. H5N1 is highly pathogenic and can mutated in dozens of highly pathogenic varieties. The two most important RNA molecules that contain by H5A1 subtype are HA and PB1. HA is a surface antigenic glycoprotein that binds the virus with the host cell to infect and the PB1 molecule is responsible for the virulence of Avian influenza.

What organs are mostly affected by the Avian influenza virus?

Avian influenza mostly attacks respiratory cells and introduces respiratory diseases to humans and animals. Affected organs included:

  • Trachea
  • Brain
  • Intestine
  • Lungs

How does Avian flu transmit infection to human beings?

Earlier we learned that Avian flu mostly infects the respiratory system. During the handling of affected birds or animals, avian flu might be transmitted to humans via eye, nose, or inhalation. Again, it can also be transmitted via saliva, cough, feces, or dead birds. Generally, Avian flu takes 5-7 days to reveal signs and symptoms, in several cases, it can take up to 17 days to manifest.  

What are the precautions that can be taken to stay safe from Avian flu?

  • Wear masks whenever you go outside
  • Use hand gloves during handling of animals
  • Keep your pets or domestic animals clean and maintain a regular schedule to clean their living area
  • Wash your hands properly after touching your pets, poultry, or domestic animals
  • Use a Home testing kit to detect flu if possible


The H5A1 subtype of Avian flu can survive longer under cold and wet conditions. An annual vaccine is already available in the market to make a shield against Avian flu but as we know, this type of influenza can mutate very fast. So, maintaining proper hygiene is the best way to fight against Avian Influenza (H5A1).

Pharmacologist I Researcher Research Coordinator Working site: Rajshahi Medical College Hospital, Rajshahi, Bangladesh Toxicology Society of Bangladesh