Argentina this week and Uruguay health emergency declared following outbreaks of the highly pathogenic H5N1 avian influenza, a rapidly spreading virus that decimated poultry and wild bird flocks, feared for decades as a possible spark of a human pandemic. This means that the 10 countries in South America that recently experienced the virus for the first time, including Peru, where more than 50,000 wild birds died last fall and more 600 sea lions in January. Combine sea lion infections with the discovery that H5N1 influenza invaded a mink farm in Spain in October, and now health authorities must grapple with the possibility that the unpredictable virus could have adapted to threaten other species.
To be clear, this does not include humans yet. While there have been outbreaks of avian influenza in recent decades that have spread to humans, only two cases have been identified in the past 12 months: Colorado adult last May and 9 year old girl from Ecuador. in January. (None of them died.) And so far, there is no evidence that the virus was able to jump from newly infected mammals to humans. But the fact that it was transmitted from birds to mammals and then spread among them points to a worrying trend.
According to the World Organization for Animal Health, at least 60 countries have recently experienced outbreaks of the H5N1 flu, named after two proteins found on the surface of the virus. This includes the US, where 43 million laying hens were either killed by bird flu last year or slaughtered to prevent the disease from spreading. These losses wiped out nearly a third of the nation’s laying hen herd; according to the US Department of Agriculture, they have reduced the supply of eggs so much that prices at the end of the year 210 percent higher than at the end of 2021. Overall, USDA estimates just under 58 million birds— mostly laying hens, turkeys, and poultry — died or were killed in 2022, with half a million more this year.
The poultry industry is huge. Part of the US alone has over 9 billion meat chickens and 216 million turkeys raised each year, plus 325 million laying hens; chicken it most consumed meat World. This scale makes it difficult to compare losses from avian influenza. But the ongoing epidemic has become the worst animal disease outbreak in US history, as well as the largest poultry outbreak ever recorded in the UK, Europe and Japan. And while observation is difficult, biologists say the damage done to wild birds has been catastrophic.
Little can be done to protect wild birds; Avian influenza is spread by seasonally migratory waterfowl, which carry the virus harmlessly. But the poultry industry relies on a complex set of behavioral and structural features, commonly referred to as biosecurity, that were developed or reinforced in the aftermath of a catastrophic outbreak that killed more than 50 million birds in 2015. Given the relentless spread of the virus, people studying the industry are starting to wonder if biosecurity can ever be strengthened enough to rule out avian influenza, and if not, what needs to be changed to keep birds and people safe.
“We know that biosecurity can and does work, but it’s a heroic effort and it may not be sustainable given today’s building styles and current workforce,” says Carol Cardona, a veterinarian and professor of avian health at the University of Minnesota College. Veterinary. “The reason I say it might work is because companies, [highly pathogenic avian flu] in 2015 there were fewer cases in 2022. So they’ve learned some lessons and changed some things, but very few of them have completely abandoned that.”
The relentless attack of H5N1 is important not only for its effects on poultry or wildlife, but also for what it portends to people. Avian flu has long been considered the animal disease most likely to develop into a global human pandemic, and even after the onslaught of SARS-CoV-2, many scientists still believe so.