Context: Every year, seasonal illnesses keep doctors and public health authorities busy. The outbreak of respiratory illnesses in children and adults caused by Influenza A ((H1N1), (H3N2), and Influenza B viruses, becomes more pronounced in winter in India.
Relevance of the Topic: Prelims: - Influenza; Types of Influenza Viruses
What is Influenza?
- Influenza (flu) is a highly-contagious respiratory illness caused by influenza viruses that impacts the nose, throat and lungs.
- Symptoms: Seasonal influenza is characterised by a sudden onset of fever, cough (usually dry), headache, muscle and joint pain, severe malaise (feeling unwell), sore throat and a runny nose.
- Risks:
- Most people recover from fever and other symptoms within a week without requiring medical attention.
- But influenza can cause severe illness or deaths, especially in people at high risk. They include- young children and people with co-morbidities like asthma, diabetes, heart disease, weakened immune systems and neurological or neurodevelopmental conditions.
Types of Influenza Viruses:
Influenza viruses are of four different types: A, B, C and D.
- 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.
- Type B:
- Influenza B almost exclusively infects humans, and is less common than influenza A.
- Type C:
- Detected less frequently and usually causes mild infections, thus does not present public health importance.
- Type D:
- Primarily affects cattle and are not known to infect or cause illness in people.
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.
Way Forward:
- Adult immunisation programmes in India must be leveraged for making Influeza vaccines available in the country. E.g., National Centre for Disease Control (NCDC) has recommended the prudent use of the Southern Hemisphere’s 2024 quadrivalent influenza vaccine.
- Expansion of the Universal Immunisation Programme to include influenza vaccines can reduce community transmission, unnecessary antimicrobial prescriptions and superimposed bacterial infections that can complicate influenza.