Prof. R,NSreenivas Gowda

The viral flu tends to spike in the winter for a major reason: the temperature. “The virus survives better in cool temperatures. Similarly, avian influenza outbreaks also increase in the winter season in our country. Let me focus only on bird flu or Avian influenza outbreaks occurring in winter and discuss the probable reasons for their occurrence and spread.

Several outbreaks of severe bird flu in Europe and Asia have been reported in recent days to the World Organisation for Animal Health (OIE), which is a sign the virus is spreading quickly again. Outbreaks of AI in European countries, southeast Asia, and Japan.

According to a new research study, the risk of the introduction of the bird flu virus on poultry farms is four times higher in the cold months of November to February than in the summer months.

This statement is true as several outbreaks are reported from many countries including our country also in the winter months.

What are the Winter months in India?

Winter Season is the coldest of the 6 seasons in India. It falls in the month of November, and December and ends in March. The season is the largest and coldest season in India. In this climate, coolness is spread everywhere in the environment. The Himalayan range experience heavy snowfall during this season.

This season favors the occurrence of bird flu in India as evidenced by recent outbreaks of avian flu in many states.

As avian flu swept through India towards the end of 2020 and early 2021, states scrambled to step up vigil and measures to control the spread of the disease. The 2020/2021 outbreak, marked by the significant involvement and mortality of wild birds, has spotlighted the need for proactive monitoring of animal disease in the environment, conserving unprotected wetland habitats to curb disease spread, and addressing knowledge gaps like the wild waterfowl–poultry interface.

News Reference

The latest bird flu outbreak in poultry and wild birds spanned 14 Indian states / Union Territories from Jammu and Kashmir in the north to Kerala in the south. Haryana, Maharashtra, Punjab, and Kerala were particularly severely affected. The latest outbreak involved highly pathogenic viral strains H5N1 and H5N8, according to the Indian government.

At least six Indian states have stepped up efforts to contain two strains of bird flu- H5N1 and H5N8 — in recent days after the deaths of thousands of migratory birds, ducks, crows, and chickens.

Officials in Himachal Pradesh said carcasses were found over the past week at a Himalayan lake that witnesses large flocks of migratory birds during the winter season.

The mass deaths came amid a cull of nearly 35,000 poultry in Kerala, where an H5N8 virus outbreak killed up to 12,000 ducks. Authorities said the slaughter was ordered within one kilometer (0.6 miles) radius of the infection epicenter.

In Haryana, state authorities said nearly 150,000 chickens died mysteriously across several poultry farms in the Barwala district. Neighboring Punjab also reported similar deaths. More than 20 farms said their flocks were wiped out by an “unknown disease” and samples have been sent to labs for testing.

Rajasthan and Madhya Pradesh have also reported hundreds of crow deaths caused by H5N1 and H5N8 over the past weeks. This state experienced nearly 4,500 crows and herons dying over several months from avian flu.

On 24th January 2021 outbreaks of Avian Influenza (Bird flu) have been confirmed in 9 states (Kerala, Haryana, Madhya Pradesh, Maharashtra, Chhattisgarh, Uttarakhand, Gujarat, Uttar Pradesh, and Punjab) for poultry birds and in 12 states (Madhya Pradesh, Haryana, Maharashtra, Chhattisgarh, Himachal Pradesh, Gujarat, Uttar Pradesh, Uttarakhand, Delhi, Rajasthan, Jammu and Kashmir, and Punjab) for Crow/Migratory/Wild birds,” the ministry of animal husbandry said in a statement.

Why does avian flu spread in winter months?

The upsurge of HPAI H5N1 epizootic waves have been linked to changes in agricultural practices, intensification of the poultry sector, and globalization of trade in live poultry and poultry products.

The unprecedented spread of H5N1 or novel avian influenza A viruses (AIV) has been the interaction between migrating waterfowl and domestic poultry.

Reasons for the spread of AI

  1. Pressure from urbanization and pollution. With the loss of habitat and increase in poultry, the wild bird and poultry buffer has reduced and increased the interaction and exchange of viruses.
  2. Local poultry birds, and equipment (fomites) movement between farms and from the farms to wetlands and to markets.
  3. 3. Domestic birds in an infected area are interacting with wild birds and some of these birds may be resident or migratory; the environment can be infected so these interactions happen in an area where there is an infection.
  4. In the Indian context, poultry plays a huge role in circulating the virus throughout the year in the form of LPAI.
  5. There was evidence of interaction between local poultry and wild waterfowl concerning H5N1 outbreaks.
  6. H5N1 outbreak occurrence was higher with greater proximity specifically to lakes, rivers, and coastal wetlands.

Most of the wild birds dead were Central Asian high-altitude bar-headed geese — one of the world’s highest flying birds — that migrate to South Asia in their thousands during the winter season.

Although wild birds are a natural reservoir of low pathogenic avian influenza (LPAI), we do not know if wild birds are a permanent reservoir of highly pathogenic avian influenza (HPAI) or how an LPAI virus transforms into an HPAI virus, one that poses a great threat to animal health and public health.….click here to read the full news