H5N1 adapts to cattle, raising red flags for India's avian flu preparedness

New study finds avian influenza virus is becoming better adapted to infect mammals

A new international study has found that the H5N1 avian flu virus is gradually becoming better adapted to infect cattle.

 

This development carries serious implications for countries such as India, which faces recurrent bird flu outbreaks and has one of the world’s largest poultry and livestock populations.

 

The research, published this week in ‘Nature Communications’, examined how avian H5N1 viruses have evolved over six decades.

 

It found that some of the more recent variants are significantly better at infecting cow cells and mammary tissues than older strains.

 

Led by scientists at the MRC–University of Glasgow Centre for Virus Research, the study comes amid ongoing H5N1 outbreaks in dairy cows in the United States since March 2024. This episode initially surprised virologists, as influenza viruses were not previously thought to cause outbreaks in cattle.

 

The detection of H5N1 in US dairy herds has revealed a new and worrying pathway for the virus to spread and adapt in mammals.

 

By analysing a large panel of viruses spanning over 60 years of evolution, researchers found that the ability of H5N1 to infect bovine cells is not driven by a single mutation, but by multiple genetic changes acquired gradually over time.

 

Crucially, H5N1 is already known for its ability to spill over into mammals, raising concerns that it could spread further into new animal hosts. As the virus continues to circulate and adapt in mammals, scientists warn that new strains could emerge that are better able to infect humans — increasing the risk of a future pandemic.

 

In October, the Coalition for Epidemic Preparedness Innovations (CEPI) said it is working with the Serum Institute of India (SII) to test how quickly the company can develop vaccines during a pandemic. It is using H5N1 bird flu as a model for a potential future “Disease X.”

 

With CEPI funding of up to $16.4 million, SII will use its baculovirus-based platform to rapidly produce and compare two H5 vaccine antigens. This would help assess how fast vaccines could be developed against an emerging pandemic threat.

 

“Influenza viruses are constantly changing, and this rapid evolution allows them to infect new animal species,” said Pablo Murcia, one of the study’s lead authors. 

 

He added, “The better adapted they become to infect mammals, the more chances they have to infect and adapt to humans — as we saw with the 2009 swine flu pandemic.”

 

For India, the findings are particularly concerning. The country reported widespread bird flu activity in 2025, with at least 41 confirmed outbreaks across 10 states, including Maharashtra, Andhra Pradesh, Telangana, Karnataka, Odisha and Uttar Pradesh.

 

While most outbreaks have affected poultry and wild birds, infections have also been reported in non-avian species such as tigers, lions, leopards and domestic cats. This highlights the expanding host range of the virus.

 

Andhra Pradesh alone recorded eight cases this year, with more than 540,000 birds dead or culled. In Odisha’s Puri district, around 6,700 birds were culled following confirmation of H5N1. Those concerns were reinforced in March 2025, when a two-year-old girl in Andhra Pradesh died after contracting H5N1 — one of the rare documented human fatalities linked to bird flu in India in recent years.

 

According to the World Health Organization (WHO), sporadic human infections with avian influenza — including H9N2 cases reported in India in 2024 — are typically mild, but are closely monitored due to their pandemic potential.

 

Medical experts say the new study underlines the urgency for India to strengthen preparedness. “It is true that avian influenza, or H5N1 bird flu, is evolving faster than expected,” said Dr Manisha Arora, director – Internal Medicine at CK Birla Hospital, Delhi.

 

She said, “Recent research has identified mutations that help H5N1 adapt beyond birds, making mammalian infection more feasible. This is particularly concerning for India, given its large poultry population and frequent human–animal contact.”

 

Dr Arora said India must enhance surveillance systems for early detection and rapid response, strengthen collaboration between healthcare providers, veterinary services and local communities, and invest in diagnostic and testing capacity.

 

Public awareness around safe handling and consumption of poultry products, improved biosecurity and hygiene practices, and preparedness for vaccine and antiviral deployment would also be critical, she added.