The same highly pathogenic avian flu virus that killed tens of millions of chickens and other birds over the past year has now moved a lot closer to infecting humans as well.
An unusual outbreak of the H5N1 virus in minks – relatives of weasels – at a Spanish fur farm last fall also exposed farm staff to the virus. Swift action by health authorities helped prevent human infections. This time.
But the bird flu is not going away. And while H5N1 continues to circulate in domestic and wild birds, killing millions of animals and limiting egg supplies, it is also closing in on human populations. “This … avian flu has the potential to become a major problem for humans,” Adel Talaat, a professor of pathobiological sciences at the University of Wisconsin-Madison, told The Daily Beast.
It may be a matter of time before H5N1 reaches large-scale “zoonosis” and makes the jump to the human species. If and when that happens, we could have another major viral crisis. On top of the COVID pandemic, worsening seasonal RSV, occasional flare-ups of monkeypox, and annual flu outbreaks.
Reports this week suggested that the current wave of avian flu could spread to mammals with more regularity. Scientists found traces of bird flu in seals that died in a “mass die” in the Caspian Sea in December, and the BBC reported this week that tests in Britain had found the virus in a range of mammals across the country. On January 9, the World Health Organization was informed that a 9-year-old girl in Ecuador had tested positive.
Bird flu is not new. Scientists first identified the virus in the 1870s. There have been dozens of major outbreaks over the years — and they’ve become more frequent and severe as the world’s domestic poultry population has increased to feed a growing human population.
H5N1, a more serious ‘highly pathogenic avian influenza’ virus – or HPAI – first appeared in China in the 1990s. It and other HPAIs have achieved zoonosis on a small scale, mainly in Asia. Several dozen people have died from bird flu in recent decades.
But so far bird flu has mostly infected, well, birds. That makes it a huge problem for poultry farmers. And for people who buy eggs, of course. The current H5N1 outbreak has killed or forced the culling of nearly 60 million chickens, turkeys, geese and ducks in the United States alone. The cull drove the price of eggs to nearly $5 a dozen in U.S. supermarkets last fall, according to the U.S. Department of Agriculture. That is several times the long-term average price.
Bird flu takes the plunge
Higher egg prices will be the least of our problems if large-scale zoonosis ever causes a human avian flu pandemic. And that’s why scientists and health officials are keeping a close eye on H5N1 and related HPAIs as they spread and mutate. For epidemiologists, the bird flu outbreak at the mink farm in northwestern Spain was a giant red flag. An ominous sign that a serious zoonosis is becoming more likely.
Spanish health officials first noticed the outbreak in early October, when mink deaths on a large farm in Galicia tripled. Biological samples from the farm’s 52,000 minks contained H5N1. It was the first time that bird flu infected minks in Europe.
Authorities ordered the culling of all minks on the affected farm. At the same time, they quarantined and tested the farm’s 11 workers. Fortunately, no one had contracted the virus.
It was a close call. And all the more worrying because no one knows for sure what happened. “The source of the outbreak remains unknown,” a team led by virologist Montserrat Agüero reported in the latest issue of Eurosurveillance, an epidemiological journal. It is possible that wild birds spread the virus to the minks. It is also possible that the pathogen was present in the mink’s feed, which contains raw chicken.
Equally disturbing, the virus didn’t just spread from birds to minks. It may also have spread from mink to other minks too, Agüero’s team discovered. “This is suggested by the increasing number of identified infected animals after the confirmation of the disease.”
That transmission after the zoonosis inside a new species is how an animal virus like H5N1 can cause another pandemic. It’s what happened with COVID, after the SARS-CoV-2 virus spread from bats or pangolins to humans in late 2019. It’s what happened to monkeypox after that pathogen first jumped from apes and rodents to humans, possibly decades ago.
How China’s COVID crisis could trigger a catastrophic virus jump
“The ability to achieve long-term transmission in a mammal is a quantum leap for flu viruses, so the mink event is a big deal,” James Lawler, an infectious disease expert at the University of Nebraska Medical Center, told The Daily Beast. “It certainly increases the risk for [a] species-leap to man.”
The Spanish bird flu outbreak has a happy ending for all involved, except, of course, for those 52,000 minks. But the next outbreak may not end so nicely. Not if scientists notice a zoonotic jump too late, or if virus transmission is outpacing health officials to cull affected animals, quarantine exposed people, and isolate the virus.
More than many viruses, bird flu calls for constant vigilance. It’s infecting more birds than ever, jumping to mammals in more places and learning new genetic tricks that increase risk to humans.
That is, our avian flu problem may get worse before it gets better. “The ongoing widespread outbreaks of HPAI are of concern across the board,” Lawler said.
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