New Delhi, Dec 18 : Even as the bird flu virus H5N1 is evolving rapidly, with the potential to become a significant threat to human health, a team of Indian researchers using an Artificial Intelligence (AI)-based model has decoded how the deadly virus can actually spillover to humans.

In the study, published in the BMC Public Health journal, the team used BharatSim -- an ultra-large-scale agent-based simulation framework for infectious diseases that was originally built for Covid-19 modelling -- to describe the sequential stages of a zoonotic spillover.

â??We modelled the possibility of initial spillover events of H5N1 from birds to humans, followed by sustained human-to-human transmission,â?? said Philip Cherian and Gautam I. Menon from the Department of Physics at the Haryana-based Ashoka University, in the paper.

â??Our model describes the two-step nature of outbreak initiation, showing how crucial epidemiological parameters governing transmission can be calibrated given data for the distribution of the number of primary and secondary cases at early times,â?? they added.

Avian flu, which first emerged in China in the late 1990s, has since occasionally infected humans.

As South and South-East Asia have the worldâ??s fastest-growing poultry markets, the region is predicted to be the likely location for an initial outbreak.

Notably, the World Health Organization (WHO) has reported 990 human H5N1 cases across 25 countries, including 475 deaths with a 48 per cent fatality rate, between 2003 and August 2025.

The computational model showed that culling birds is the most effective measure to curb H5N1 outbreaks, both in the case of a farm outbreak or a wet market. However, this will work only when no primary infection has occurred.

â??In our study of the tertiary attack risk, we found that even if an infection of a primary case occurs, onward infections are limited if cases are isolated and their household contacts quarantined. However, once tertiary contacts are infected, establishing control becomes impossible unless far more stringent measures are applied, including a total lockdown,â?? the experts noted.

They stressed that it is in the very early stages of an outbreak that control measures make the most difference.

"Once community transmission takes over, cruder public-health measures such as lockdowns, compulsory masking, and large-scale vaccination drives are the only options left,â?? the researchers added.

The study shows how such models allow for the systematic real-time exploration of policy measures that could constrain disease spread, as well as guide a better understanding of disease epidemiology for an emerging infectious disease.

/IANS