Bird Flu: Avian Influenza

• 22 Jul 2021

Why in News

Recently, the first human death was recorded due to Bird Flu in India this Year. This was caused by H5N1 Avian Influenza Virus.

• Earlier, China reported the first human infection of H10N3 bird flu.

Key Points

• About:
  
  • A disease caused by avian influenza (AI) Type A viruses found naturally in wild birds worldwide.
    
    • AI viruses are broadly classified as low pathogenic AI (LPAI) and highly pathogenic AI (HPAI) viruses, based on their pathogenicity. H5N1 strains come under HPAI viruses.
  • The virus can infect domestic poultry including chickens, ducks, turkeys and there have been reports of H5N1 infection among pigs, cats, and even tigers in Thailand zoos.
• Impact:
  
  • Outbreaks can lead to devastating consequences for the country, particularly the poultry industry.
  • Farmers might experience a high level of mortality in their flocks, with rates often around 50%.
• Infection in Humans:
  
  • The most common route of virus transmission is direct contact with infected birds, either dead or alive, or contact with contaminated surfaces or air near the infected poultry.
  • Human-to-human transmission of the H5N1 virus is very rare.
  • Children and adults below 40 were seen to be the most affected and mortality was high in 10-19 years olds.
• Symptoms in Humans:
  
  • Range from mild to severe influenza-like illnesses such as fever, cough, sore throat, muscle aches, nausea, abdominal pain, diarrhea, vomiting.
  • People can also develop severe respiratory illness (e.g., difficulty breathing, pneumonia, acute respiratory distress, viral pneumonia) and altered mental status, seizures etc.
• Prevention and Eradication:
  
  • Strict biosecurity measures and good hygiene are essential in protecting against disease outbreaks.
  • If the infection is detected in animals, a policy of culling infected and contact animals is normally used in an effort to rapidly contain, control and eradicate the disease.
  • WHO’s global laboratory system, the Global Influenza Surveillance and Response System (GISRS), identifies and monitors strains of circulating influenza viruses, and provides advice to countries on their risk to human health and available treatment or control measures.
• Status of Bird Flu in India:
  
  • Fresh cases of bird flu were reported in different states of India between December 2020-January 2021 causing alarm across the country.
  • Previously in 2019, India was declared free from Avian Influenza (H5N1), which had also been notified to the World Organization for Animal Health (OIE).
    
    • The OIE is an intergovernmental organisation responsible for improving animal health worldwide. It is headquartered in Paris, France.

Types of Influenza Virus

• There are four types of influenza viruses: influenza A, B, C, and D
  
  • Influenza A and B are the two types of influenza that cause epidemic seasonal infections nearly every year.
  • Influenza C mainly occurs in humans, but has been known to also occur in dogs and pigs.
  • Influenza D is found mainly in cattle. It’s not known to infect or cause illness in humans yet.

Avian influenza Type A viruses

• Type A viruses are classified based on two proteins on their surfaces – Hemagglutinin (HA) and Neuraminidase (NA). There are about 18 HA subtypes and 11 NA subtypes.
• Several combinations of these two proteins are possible e.g., H5N1, H7N2, H9N6, H17N10, H18N11 etc.
• All known subtypes of influenza A viruses can infect birds, except subtypes H17N10 and H18N11, which have only been found in bats.

Way Forward

• There is a need to enhance monitoring of wild bird and animal disease in our environment to act as an early warning system of change/arrival of potential diseases.
• There is a need for a well-designed study to screen poultry and domestic waterfowl for low pathogenic viruses.
• A study found that H5N1 outbreak occurrence was higher with greater proximity specifically to lakes, rivers, and coastal wetlands, by blocking the mixed-use of surface water by domestic poultry and wild waterfowl, cycling of Avian Influenza can be interrupted.
• The emphasis should be on monitoring multiple waterbird sites of local, national, and international importance.

Source: IE