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Dozens of outbreaks bird flu have been detected in wild birds and commercial poultry across the UK
Scientists are sounding the alarm over the potential for bird flu to spark the next pandemic, as new modelling suggests authorities would have as little as two days to act before an outbreak spirals out of control.
Researchers in India used a detailed computer simulation to estimate how quickly a mutated strain of H5N1 avian influenza could spread if it jumped from poultry to people. It comes as cases of bird flu continue to rise wild birds across the globe, sparking outbreaks in poultry farms and even dairy cows in the US.
The computer model – built using BharatSim, originally designed for Covid-19 – recreated a community of 9,667 residents in Namakkal district, Tamil Nadu, a major poultry hub with over 1,600 farms. The virus was seeded at a mid-sized farm or wet market, where the first human cases are most likely to appear.
Primary contacts infected family members, who then passed the virus into wider networks through workplaces, schools and markets. Within 48 hours, tertiary contacts – or friends of friends – began to emerge. The findings highlight the narrow window in which public health measures like lockdowns must be deployed.
Quarantining households early proved to be the most effective intervention, but only when the number of infected people was as low as two. Culling infected birds also helped, but only if this was done within 10 days of detection.
“The earlier birds are culled, the larger the probability a spillover can be prevented,” the researchers said. Once cases reached 10, the simulations showed the virus was overwhelmingly likely to have infiltrated the wider population. At that point, the study found, only sweeping measures such as “lockdowns, compulsory masking, and large-scale vaccination drives” could slow transmission.
“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 Gautam Menon of Ashoka University told the BBC.
As bird flu continues to circulate, health authorities say the risk of human transmission is very low. “But low isn’t none,” Nikki Ikani, Assistant Professor of Intelligence & Security at Leiden University and King’s College London, warned. “And if it were to occur, the consequences could be catastrophic. Most people have some immunity to the seasonal flu strains. We probably have none to H5,” she wrote for The Conservation.
She added: “Human cases remain rare: only 992 confirmed H5N1 infections worldwide since 2003, though with a near-50% fatality rate. But the numbers are increasing.”
Last month, the US reported its first ever case – and death – from H5N5 bird flu, a strain of the virus never detected in humans before. The patient is believed to have had close contact with infected birds on a farm, and authorities stress the risk to the wider public is low.
The Indian team of scientists hopes the real-time simulation could guide early decision-making if bird flu ever crosses into humans widely. They wrote: “Our simulations can be run in real time, responding to initial reports of cases.”
