The bird flu outbreak has taken an ominous turn

This week, Argentina and Uruguay declared nationwide well being emergencies following outbreaks of extremely pathogenic avian influenza H5N1, the fast-moving virus that destroys poultry flocks and wild birds and for many years has been feared as a attainable spark for a pandemic amongst individuals. That makes 10 South American international locations which have just lately marked their first-ever encounter with the virus, together with Peru—the place greater than 50,000 wild birds died final fall, and greater than 600 sea lions in January. Combine the sea-lion infections with the revelation that H5N1 flu invaded a mink farm in Spain in October, and well being authorities should now confront the likelihood that the unpredictable virus could have tailored to threaten different species.

To be clear, this doesn’t but embrace individuals. Although previous many years have witnessed bird flu outbreaks that unfold to people, solely two circumstances have been recognized prior to now 12 months: a Colorado grownup final May, and a 9-year-old lady in Ecuador in January. (Neither died.) And there’s no proof but that the virus has been in a position to bounce from newly contaminated mammals to individuals. But the truth that it was transmitted from birds to mammals, after which unfold amongst them, signifies a disquieting development.

According to the World Organization for Animal Health, not less than 60 international locations have just lately skilled outbreaks of H5N1, which is known as for 2 proteins discovered on the virus’s floor. That consists of the US, the place 43 million laying hens had been both killed by avian flu final yr or slaughtered to stop the illness from spreading. Those losses took out virtually a 3rd of the nationwide flock of laying hens; in keeping with the US Department of Agriculture, they reduce into egg provides a lot that costs on the finish of the yr had been 210 % larger than on the finish of 2021. Overall, the USDA estimates slightly below 58 million birds—largely layers, turkeys, and yard poultry—died or had been killed in 2022, and one other half-million thus far this yr.

The poultry business is gigantic. Just the US portion contains greater than 9 billion meat chickens and 216 million turkeys grown every year, plus 325 million laying hens; rooster is the most-consumed meat worldwide. That scale makes it troublesome to place the losses from bird flu into context. But the continuing epidemic has grow to be the worst animal-disease outbreak in US historical past, in addition to the most important poultry outbreak ever recorded within the UK, Europe, and Japan. And although surveillance is troublesome, wildlife biologists say the harm to wild birds has been disastrous.

There could also be little that may be completed to guard wild birds; avian flu is unfold by seasonally migrating waterfowl, which carry the virus with out being harmed by it. But the poultry business depends on a fancy set of behaviors and constructing options, broadly known as biosecurity, that it developed or strengthened after a catastrophic outbreak killed greater than 50 million birds in 2015. Given the virus’s relentless advance, individuals who research the business are starting to ask whether or not biosecurity can ever be hardened sufficient to exclude avian flu—and if not, what has to alter to maintain birds and people secure.

“We know that biosecurity can work and does work, but it’s a heroic effort, and it may not be sustainable given current building styles and current workforce,” says Carol Cardona, a veterinarian and professor of avian well being on the University of Minnesota College of Veterinary Medicine. “The reason I say it can work is that companies that had [highly pathogenic avian flu] in 2015 had fewer cases in 2022. So they learned some lessons and changed some things—but very few of them kept it out completely.”

The relentless assault of H5N1 is necessary not only for its affect on poultry or wildlife, however for what it portends for individuals. Avian flu was lengthy thought-about the animal illness probably to interrupt out into a worldwide human pandemic, and even after the onslaught of SARS-CoV-2, many scientists nonetheless really feel that means.

The H5N1 subtype first spilled from birds to people in 1997 in Hong Kong. It sickened 18 individuals and killed six of them—small numbers, however a disturbing 33 % mortality fee. Since then, variants of H5N1 have periodically contaminated individuals, inflicting 868 human circumstances via 2022 in keeping with the World Health Organization, and 457 deaths. Those numbers symbolize a 52 % mortality fee—however on the identical time, an indication that the virus had not tailored sufficient to unfold simply from individual to individual and ignite massive outbreaks.

Still, scientists are all the time awaiting the virus to seek out conditions that may encourage these diversifications. For occasion: Spanish and Italian scientists disclosed final month that in October 2022, an H5N1 variant contaminated minks on a fur farm in Northwest Spain. The virus might need been handed to a single mink by a wild bird, or by way of rooster carcasses used for feed. But as soon as on the farm, it made minute diversifications that allowed it to unfold from one mink to a different. To cease the outbreak, all of the farm’s minks—virtually 52,000—had been killed.