‘Unprecedented’ Bird Flu outbreak threatens more chickens

MASS — It is a bird flu outbreak unlike any other.

“Right now, we have an unprecedented amount of highly pathogenic avian influenza in our wild bird species,” said Victoria Hall, MD, DVM, executive director of the Raptor Center at the University of Minnesota. “It’s been circulating much longer than we’ve seen with outbreaks in the past.”

Normally, bird flu outbreaks resolve in a matter of months. But this one has been going strong since late 2021.

“Any time flus are circulating for a long time, they have a chance to mutate, they have a chance to change,” said Hall. “But it seems like it’s very low risk to humans at this time.”

Humans contract avian influenza by coming into contact with infected birds. But some epidemiologists see signs that this outbreak is edging closer to becoming a broader threat -- based on infections among other mammalian species.

“When you see 68 sea lions die in one place and you check the virus, and they all have the same virus that tells you something really important,” said Barry Bloom, PhD, an immunology and infectious disease expert at The Harvard School of Public Health. “It says the virus is spreading mammal to mammal.”

“Going from birds to humans is hard,” Bloom added. “And once it gets into mammals it usually stops.”

But public health agencies are monitoring the bird flu epidemic in case it doesn’t stop in mammals. The fear: that a mutant could arise enabling human to human transmission.

“The likelihood of this event still feels relatively small,” said Jessica Leibler, DrPH, ScM, an environmental epidemiologist at the Boston University School of Public Health. “But each time that there’s mammalian species that are infected it becomes one step closer and the risk becomes a little bit higher.”

And migratory birds are spreading that risk to every part of the world -- without getting sick themselves. But bird flu can be devastating to their brethren.

“Wild birds can secrete this virus through their respiratory secretions as well as through their feces,” said Hall. “So if you have backyard chickens and they interact with wild birds they could pick up virus particles. Chickens and raptors, like eagles and hawks in particular, get very, very sick and often die from this virus.”

In fact, the possibility of mass bird flu infections forced farmers in numerous countries to slaughter millions of chickens -- something that contributed to the high price of eggs earlier this year.

“History is full of influenza pandemics before 1918 that wiped out hundreds of millions of people,” Bloom said. “So it has to be taken seriously.”

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