New Delhi: A growing outbreak of the H5N1 bird flu virus has affected more than 1,000 dairy herds across the United States since March 2024, raising serious concerns among health experts.
The infection has already jumped to humans, with over 70 confirmed cases and one reported death. The deceased, a 65-year-old man in Louisiana, was hospitalised in January 2025 after experiencing severe respiratory symptoms. Health officials noted he had preexisting conditions and had come into contact with sick birds from a backyard flock.
The virus, which was previously associated mainly with poultry and wild birds, is now firmly established in dairy cattle—an unusual and worrying development.
Experts warn of mutation risk in mammals
Scientists and public health experts are alarmed by the increasing ability of the virus to infect mammals. According to the Global Virus Network (GVN), the ongoing presence of H5N1 in animal populations—particularly in mammals—raises the risk of the virus mutating in a way that could allow human-to-human transmission.
Dr Sten H. Vermund, dean of the USF Health College of Public Health at the University of South Florida and chief medical officer of GVN, emphasised the need for a swift and strategic response.
“Understanding the current landscape of H5N1 infections is critical for effective prevention and response,” he said. He also pointed out that “The virus’ ability to infect both animals and humans, combined with recent genetic changes, underscores the importance of proactive surveillance and rapid response measures.”
Adding to the concern, Dr Marc Johnson, a virologist at Missouri University, wrote on X: “This virus might not go pandemic, but it is really trying hard, and it sure is getting a lot of opportunities.”
CDC urges caution but says public risk still low
The US Centers for Disease Control and Prevention (CDC) has acknowledged the seriousness of the outbreak but maintains that the risk to the general public remains minimal. However, the agency strongly advises caution for individuals in close contact with infected animals.
The CDC reports that H5 bird flu is already widespread in wild birds globally and is now causing consistent outbreaks in both poultry and dairy cattle across the US. Several recent human cases have been reported among dairy and poultry workers.
To contain the situation, the CDC is working closely with state governments to monitor anyone who has had contact with infected animals. The agency is also actively tracking the spread of the virus through its national flu surveillance systems.
H5N1: A virus that keeps moving
H5N1 first emerged in birds but has shown increasing ability to infect other species. Over the years, isolated human cases have typically involved direct contact with sick birds.
What sets this outbreak apart is the virus’s leap into the dairy sector and its broader mammalian reach. This could give the virus more chances to evolve in ways that make human transmission easier.
The spread through dairy cows also complicates detection. Unlike poultry, cows may show subtle symptoms or none at all, making the virus harder to trace in early stages.
Authorities are now calling for improved biosecurity on farms, standardised testing protocols, and vaccines for both animals and workers. As the virus adapts, they say the human response must move faster too.
