A man who predicted Covid-19 years before it swept the and killed millions fears the next pandemic could already be unfolding.

writer David Quammen, who previously warned would likely come from a wet market - possibly in - says poses the greatest risk of sparking the next global pandemic. His warning comes after the H5N1 strain of the flu was detected in a sheep on a farm in Yorkshire this week, the confirmed. The case, along with growing infections across the pond, has sparked concern amongst health officials and experts. Quammen told MailOnline: “I have high concerns about bird flu. If you're going to make a prediction about what would be the next big one now, a would probably say, well, bird flu has the best chance of being our next pandemic virus.

“But there's always a lot of randomness built into this because these viruses have high mutation rates and mutation is basically a random process,” he added. In the US, H5N1 has spiralled across farms, affecting more than 1,000 dairy herds, wiping out 168 million poultry birds, and resulting in over 70 confirmed human cases - including the first known death linked to the virus.

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Quammen warned that if the virus mutates to spread easily between humans, the consequences could be severe. “Just the way the Covid virus went from being a rare virus to being a virus in humans and in wildlife all over the planet, that could happen starting tomorrow with bird flu,” he said.

The H5N1 strain, first detected in the US in 2022, has also been found in a range of animals including cats, raccoons, skunks, wild , bears and dolphins. Human infections have so far been linked to contact with infected animals, with no evidence yet of person-to-person transmission.

While the US Centers for Disease Control and Prevention (CDC) says risk of bird flu to people remains low, experts have warned that mutations and reassortments - where two viruses simultaneously infect the same host and exchange genetic material - could increase the risk of human transmission.

The Global Virus Network (GVN) has called on governments to bolster surveillance and tighten biosecurity measures to avoid a repeat of the early COVID-19 chaos. Quammen said: “It might take four or five mutations of just the right combination to do that, and each of those mutations is a highly improbable event. And the combination of the right four or five is therefore an even more improbable event.”

But with the virus mutating rapidly, the risk could be growing. “Bird flu is replicating itself by the billions in each individual bird that it infects - probably every day,” he said. “My sense is this virus is replicating itself around the continually right now, in millions of wild birds, in probably millions of chickens and in quite a few cows and other mammals.

“All of those replications, each individual viral replication in each animal, is a spin of the roulette wheel. I'm not saying it's a certainty that bird flu will be our next pandemic; I'm just saying that it's a very very distinct possibility.”

Since March 2024, the US has reported 70 confirmed human cases of bird flu, mostly mild and primarily among farm workers exposed to infected poultry or dairy cows. Traces of the virus have also been found in milk sold in - a discovery that Quammen said made him “absolutely” concerned about food safety and public health. In England, there have been more than 30 outbreaks of the virus on farms, with most in the eastern regions.

There are an estimated 34 billion chickens worldwide, many of them reared in cramped, industrial conditions. Quammen warned that such settings are ideal for viral evolution. “These massive industrial agriculture systems are petri dishes for the evolution of viruses,” he said.

Quammen also pointed to broader human behaviours - including climate change, overpopulation, overcrowding and unsanitary living conditions - as major contributors to the risk of future pandemics.