Bird Flu on the move worldwide, Kerala Orders culling of thousands of Birds

Context

Recently, Authorities in the district of Kottayam have ordered the culling of at least 8,000 birds, including poultry and ducks.

Bird flu in Kerala:

Two panchayats in Kerala’s Kottayam district – Arpookara and Thalayazham – reported a bird flu outbreak.
Authorities had ordered the culling of around 8,000 ducks, hens, and other domestic birds within a kilometre radius of the affected areas.
Tests conducted at the National Institute of High-Security Animal Diseases (NIHSAD) in Bhopal confirmed it to be the H5N1 strain of the virus.
The H5N1 strain is the most prevalent one now across the world.

What is bird flu?

Avian influenza or Bird Flu refers to the disease caused by infection with avian (bird) influenza (flu) Type A viruses.
These viruses occur naturally among wild aquatic birds worldwide and can infect domestic poultry and other bird and animal species.
It is a zoonotic disease that affects wild and domestic bird populations.
Avian flu viruses do not normally infect humans.

Spread:

The disease makes its presence felt particularly during winter in most of India and other parts of the globe.
This is because, as wintering, migratory birds arrive and bring pathogens with them.
Temperature is also a factor: the virus thrives better in cooler climes, thus enabling its spread during winter.

Concern:

Bird flu is a concern because the virus can spread quickly among domestic birds, causing drastic economic losses.
It can also spill over to people, and poses a significant public health risk.
Outbreaks can lead to devastating consequences for the country, particularly the poultry industry.

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.

Measures against bird Flu:

Revised Action Plan for Prevention, Control & Containment of Avian Influenza (2021)
Opting Culling method
Cleansing and disinfecting and reduction of people’s movement.
Vaccination to humans: Avian Influenza vaccine is available outside India e.g. the USA has developed the vaccine for Human infection.

Reason for Frequent Occurrence of Bird Flu:

Source: Wild birds are considered the natural reservoirs of the bird flu viruses, and it is typical for an outbreak to coincide with the season of arrival of migratory birds.
Migration of Virus: Migratory birds from faraway countries in the northern hemisphere such as Mongolia and Kazakhstan are said to have brought the virus to India.
The bird flu spreads through their droppings, contaminating the water bodies they visit.
Destination: According to the World Health Organization (WHO), more than half of the world’s bird flu incidents take place in the Central Asian Flyway (CAF), which covers almost the entire Indian subcontinent.
Man-Made Reason: Further, WHO believes that continuous growth in poultry farming under poor sanitary conditions was sustaining the virus, with multiple susceptible