Context: A global outbreak of H5N1 (a highly pathogenic avian influenza virus) has been spreading across the world since late 2020. Recent human cases of H5N1 infections have raised alarms regarding its potential to turn into pandemic.
About Influenza:
- Influenza (flu) is a highly-contagious respiratory illness caused by influenza viruses.
- Symptoms of influenza include acute onset of fever, cough, sore throat, body aches and fatigue.
Influenza viruses are of four different types: A, B, C and D.
i. Type A:
- Influenza A is associated with severe respiratory illness and deaths in humans.
- Only influenza type A viruses are known to have caused pandemics.
- They are further classified into subtypes according to the combinations of the proteins on the surface of the virus. E.g.,
- H3N2 (HongKong Flu) and H1N1 (Swine Flu) viruses are subtypes of Influenza A virus.
- H5N1 (Avian influenza/ Bird Flu) is also a subtype of the Influenza A virus that primarily infects birds, but can also infect humans and other mammals.
ii. Type B: Influenza B almost exclusively infects humans, and is less common than influenza A.
iii. Type C: Detected less frequently and usually causes mild infections, thus does not present public health importance.
iv. Type D: Primarily affects cattle and are not known to infect or cause illness in people.
H5N1 Virus (Avian influenza/ Bird Flu):
- H5N1 (Avian influenza/ Bird Flu) is a subtype of the Influenza A virus that predominantly infects birds, but can also infect humans and other mammals.
- The virus can infect people in close contact with infected birds, including dairy or poultry farm workers.
- Recent human cases of H5N1 in Canada and California have increased concerns about the possible mutations in the virus that could facilitate human-to-human transmission.
- Genome sequencing identified a particular mutation which is linked to faster replication of the virus in human cells and greater severity of illness.
- The findings raise concerns about the potential of the virus to cause more severe respiratory illness in humans.
Influenza viruses are constantly evolving, the factors include:
- High population density, poor hygiene practices, weather conducive to the survival and spread of the virus increase the risk of flu transmission.
- Indiscriminate antimicrobial use due to the absence of definitive diagnosis and influenza symptoms coinciding with other acute respiratory infections.
- Low Vaccination rates as strategies for influenza prevention and control have not been prioritised by the Indian Medical Association. Influenza vaccine is not included into the government’s Universal Immunisation Programme.
- Due to climate change, seasonal epidemics of influenza may shift spatially and temporally, with rising temperatures and abnormal rainfall patterns being contributing factors.