Mountain lion cubs. Snow geese. Foxes. Great horned owls. Bald eagles. Chickens.
These animals were all Wyoming casualties of the latest strain of the bird flu that swept across the country the last two years. In neighboring states, there were even reports of grizzly and black bears being euthanized after contracting the virus.
The most recent outbreak killed at least hundreds of birds in Wyoming, but health officials say the true number is likely higher because most bird flu stats in the U.S. rely on voluntary public reporting. Nationally, millions of animals died.
The last reported case of a casualty in Wyoming was May 15.
“That was a great horned owl,” said Jessica Jennings-Gaines, a wildlife disease specialist overseeing Wyoming Game and Fish’s Wildlife Health Laboratory.
The two-month break in confirmed deaths reflects a broader, national lull in confirmed avian influenza infections. But experts remain concerned and vigilant. Discussions are ongoing about how to address what the U.S. Department of Agriculture calls “the largest animal health outbreak in this country’s history.”
While it’s unclear what the avian influenza will do next — return with migrating birds in the fall, mutate further or fade into the background — history shows that some version of the virus has persisted for decades.
How did we get here?
The bird flu has evolved as it’s spread across the world following its discovery in China in 1996. It wasn’t until 2015 that an outbreak made a big impact in the U.S., though its effects then were largely limited to certain bird species.
Its latest iteration, which is a form of H5N1 highly pathogenic avian influenza, first arrived in the U.S. via wild birds in late 2021, according to the CDC. It showed that the virus can now spread more easily — and to more kinds of animals — than ever before.
“In 24 years of tracing this particular H5N1 flu lineage, we haven’t seen this ability to cause disease but also be maintained in these wild bird populations,” stated Dr. Richard Webby with St. Jude Children’s Research Hospital in a May press release.
Webby examined genetic changes within the bird flu and how they contributed to its spread.
Nationally, nearly 60 million poultry birds have reportedly died — either by the virus and its near-100% mortality rate or via the mandatory culling to stop its spread — exacerbating issues like egg shortages and inflated costs. More than 7,000 wild animals have died from the virus, too, excluding those that weren’t found and tested by humans.
Since 2021, federal agencies report 430 poultry have been affected in Wyoming. However, that’s likely an undercount, according to state veterinarian Hallie Hasel.
“It’s not just USDA, [poultry farmers] don’t want us in their backyard,” Hasel said. “They don’t want to acknowledge that they have it.”
Confidentiality is maintained by only reporting at the county level, she said, “but folks prefer not to report it, and that’s their choice.”
Hundreds of wild birds and mammals were confirmed or suspected to have been affected by the virus around the state, too. Again, every death likely wasn’t accounted for, according to Jennings-Gaines.
“We’re not actively going out all day long looking over every inch of Wyoming for dead birds,” she said, calling their efforts “enhanced passive surveillance.”
“But we really rely on the public to give us calls,” she added.
Beyond those already listed at the top of this story, other cases of wild bird deaths caused by the virus — or suspected to be caused by it — in Wyoming include: Canada goose, magpie, red tailed hawk, sharp-shinned hawk, sandhill crane, turkey vulture, wild turkey, Swainson’s hawk, wood duck, golden eagle, Cooper’s hawk, peregrine falcon, common goldeneye, eared grebe, horned grebe, blue-winged teal, common loon, trumpeter swan and American kestrel.
What about human infections?
So far, there’s only been one documented case of a person testing positive for the virus in the U.S., according to the CDC. The man, who worked on a poultry farm in Colorado, suffered only one symptom: fatigue. The CDC notes that he may not have been actively infected — a virus may have just landed in his nose before getting a nasal swab — but infection can’t be ruled out.
Worldwide, there have been 878 documented human infections of bird flu and 458 deaths — though only 18 cases and 3 deaths occurred since 2020, according to the World Health Organization.
Overall, there’s not a significant risk to people with this particular variant of the virus, according to the recent research at St. Jude Children’s Research Hospital. Of course, this virus could mutate again, posing different risks.
International health organizations made a call earlier this month for countries to bolster monitoring and curb the spread of the bird flu, citing concerns about the virus becoming better able to infect humans.
These international groups as well as Congress have also taken up conversations about poultry vaccines for the virus — several such vaccines are in trial phases — though the vaccines may also be fraught for a number of reasons. They’ll likely take time, for starters. And like the seasonal flu affecting humans, this virus may mutate and quickly overcome vaccinations, according to an April media briefing from Dr. Yuko Sato, the poultry extension veterinarian and diagnostic pathologist at Iowa State University.
Beyond that, Sato said, there are issues like trying to monitor the virus’ spread when vaccinated chickens aren’t showing many symptoms. And then there’s the practical challenges of other countries not wanting U.S. poultry that’s been vaccinated, she added.
While most Wyoming farmers aren’t housing massive poultry operations with thousands of birds, Hasel said there are some who do export them.
“[A vaccination effort] is something that would impact us as a state as well, for our poultry producers that do export birds,” she said.
What does the future hold?
Predictions are always challenging when it comes to viruses, but there are nearly three decades of research when it comes to the bird flu showing how it’s been able to adapt to survive.
Even if it doesn’t make an immediate appearance this fall, Hasel warns that it could still show up the following spring.
“So it’s not something that we can cross off the radar at all,” she said.
That means folks should still be careful, she said, trying to keep any poultry flocks away from virus carriers like ducks or geese.
Anyone who finds domestic poultry that are acting sick can contact the Wyoming Livestock Board at 307-777-8270 or 307-777-6440. There are also national programs through the CDC and USDA to help prevent or identify the bird flu in flocks.
If someone comes across sickly or freshly dead animals of any sort that don’t show signs of why they died, they should contact Game and Fish. To report possible bird flu deaths, specifically, the link for that is here.
Aside from the bird flu, Jennings-Gaines said there are plenty of other animal illnesses around that officials can use the public’s help in monitoring. That includes epizootic hemorrhagic disease and bluetongue — affecting deer, pronghorn and other ruminants — and rabbit hemorrhagic disease.