H5N1 Bird Flu: Insights from Indian Researchers on Human Transmission Risks

Fri Dec 19 2025 03:27:09 GMT+0200 (Eastern European Standard Time)

Indian scientists model the potential spread of H5N1 avian influenza among humans to enhance public health preparedness.

A new study by Indian researchers using advanced simulations has explored how the bird flu (H5N1) virus could jump from birds to humans, possibly leading to a pandemic. By modeling scenarios based on real-world data, the researchers emphasize the critical role of timely interventions to prevent secondary infections and contain outbreaks effectively. This research aims to provide insights for public health officials on risk management strategies.

For years, scientists have warned that bird flu - better known as H5N1 - could one day make the dangerous leap from birds to humans and trigger a global health crisis.

Avian flu - a type of influenza - is entrenched across South and South-East Asia and has occasionally infected humans since emerging in China in the late 1990s. From 2003 to August 2025, the World Health Organization (WHO) has reported 990 human H5N1 cases across 25 countries, including 475 deaths - a 48% fatality rate.

In the US alone, the virus has struck more than 180 million birds, spread to over 1,000 dairy herds in 18 states, and infected at least 70 people - mostly farmworkers - causing several hospitalizations and one death. In January, three tigers and a leopard died at a wildlife rescue center in India's Nagpur city from the virus that typically infects birds.

Symptoms in humans mimic a severe flu: high fever, cough, sore throat, muscle aches and, at times, conjunctivitis. Some people have no symptoms at all. The risk to humans remains low, but authorities are watching H5N1 closely for any shift that could make it spread more easily.

A bird flu pandemic, researchers say, would begin quietly: a single infected bird passing the virus to a human - most likely a farmer, market worker or someone handling poultry. From there, the danger lies not in that first infection but in what happens next: sustained human-to-human transmission.

The concern is what prompted new peer-reviewed modeling by Indian researchers Philip Cherian and Gautam Menon of Ashoka University, which simulates how an H5N1 outbreak might unfold in humans and what early interventions could stop it before it spreads. The modeling uses real world data and computer simulations to play out how outbreaks might spread in real-life scenarios.

“The threat of an H5N1 pandemic in humans is a genuine one, but we can hope to forestall it through better surveillance and a more nimble public-health response,” Prof Menon noted.

The key takeaway for policymakers is how narrow the window for action can be before an outbreak spirals out of control. The researchers advise that once cases rise beyond roughly two to 10, the disease is likely to spread beyond primary and secondary contacts.

To keep the study grounded in real-world conditions, the researchers chose a model of a single village in Namakkal district, Tamil Nadu - the heart of India's poultry belt. The simulations highlighted an awkward trade-off in quarantine processes; enforcing it too early may risk increased transmission among household members, while delaying could lead to uncontrollable spread of the virus.

The simulations underscore the importance of timely interventions in culling birds and quarantining close contacts upon the first signs of infection. Failure to do so could result in a rapid escalation of infections and necessitate more restrictive measures to control an outbreak.