H5N1 vs H5N2

Why in news?

Recently, World Health Organization (WHO) has confirmed the first-ever human death caused by the H5N2 strain of avian influenza.

What is an Avian influenza?

• Bird flu- It is a viral infection that primarily affects birds but can also infect mammals, including humans.

Avian influenza is a zoonotic disease, meaning it can spread from animals to humans.

• Transmission- It spreads from infected birds to humans through close contact with birds or contaminated environments, such as in backyard poultry farm settings and at markets where birds are sold.
• Symptoms-
  • Respiratory symptoms- Cough, shortness of breath, difficulty breathing, and sore throat.
  • Non-respiratory symptoms- Fatigue, Muscle or body aches
• Asymptomatic infection- Some individuals may not show symptoms (asymptomatic) despite being infected, particularly those with exposure to infected animals or their environments.

What is a novel avian influenza A virus?

• About- It is a newly identified subtype of influenza A virus that originates in birds (avian species) but has undergone mutations allowing it to infect other species, including humans.
• Novel viruses- These viruses are termed "novel" because they possess unique genetic characteristics not previously identified in existing influenza strains.
• Host- It primarily infect birds, both wild and domestic (e.g., chickens, ducks, and turkeys), it can potentially infect other animals, including mammals like pigs and humans, especially if the virus adapts to these hosts.
• Transmission-

• Health impact- In humans, infections can range from mild respiratory symptoms to severe disease and even death, depending on the virus strain and individual health factors.
• Public health concern- Novel avian influenza viruses are closely monitored due to their potential to cause pandemics.
• Examples-
  • H5N1- First identified in 1997 in Hong Kong it has caused numerous outbreaks in birds and sporadic human infections with high mortality rates.
  • H7N9- Emerged in China in 2013, causing severe respiratory illness in humans.
  • H5N2- Recently noted for its first human infection case in Mexico
• H5 viruses- They are classified based on two types of protein on their surfaces: hemagglutinin, or H, which plays a crucial role in allowing the virus to infect cells, and neuraminidase, or N, which helps the virus spread.

People become infected with H5 viruses through direct contact with birds and poultry, not other humans.  

What are the major differences between H5N1 vs H5N2?

References

1. Down to Earth | Avian flu H5N1 spreads to 40 cattle in Minnesota, US.

2. Down to Earth | WHO confirms first death from bird flu strain H5N2 in Mexico.

3. Indian Express | First human death from H5N2 bird flu.