Reporting Highlights
Gone With The Wind: After a bird flu outbreak tore through Midwestern barns, killing hens and spiking egg prices, the USDA didn’t investigate whether the virus was airborne. ProPublica did.
“Seems So Likely”: Experts say ProPublica’s analysis offers a plausible explanation for how the wind could have helped spread the virus, exposing a flaw in the USDA’s playbook to fight it.
Vaccine Resistant: To combat bird flu spread, other countries have authorized poultry vaccines, but the U.S. has held off amid political and economic opposition.
These highlights were written by the reporters and editors who worked on this story.
Nearly a million chickens packed the barns at Howe’s Hens last Christmas Eve when the first of them tested positive for bird flu. The deadly virus spreads so fast that even if only one hen is infected, farmers are legally obligated to kill all of the others. Massive mounds of carcasses soon appeared outside the Ohio egg farm, covered in compost.
The slaughter wasn’t enough. The virus tore through industrial barns in Darke County and moved on through one of the most poultry-dense regions in America, crossing the state line into Indiana. Rows of raised earth became a familiar sight alongside the roads that crisscrossed the plains. The air stank of death, recalled cafe owner Deborah Mertz: “The smell of every bird in Mercer County, rotting.”
The U.S. Department of Agriculture urged farmers to follow a longstanding playbook that assumes that bird flu is spread by wild birds and tracked into barns with lax safety practices. The agency blamed the outbreak on “shared people and equipment.”
Three years into a brutal wave of the virus, industry leaders raised evidence that bird flu was entering barns differently and evading even the strictest protocols. They suspected it could be airborne and begged officials to deploy a proven weapon against the disease: a vaccine for poultry.
The USDA didn’t do that or explore their theory, and its playbook failed: In just three months, the virus that erupted in a single Ohio farm spread to flocks with over 18 million hens — 5% of America’s egg layers. All were killed to try to stop the contagion, and egg prices hit historic highs, surpassing the previous fall’s spike, which Donald Trump had cited as a massive failure of economic leadership in his successful campaign for the presidency.
A sign in a grocery store in New York City in January notifies customers of an egg shortage due to bird flu. Lindsey Nicholson/UCG/Universal Images Group via Getty Images
After a quiet summer, bird flu is on the move again, and experts say it poses an escalating threat. While the virus doesn’t appear capable of spreading from human to human, it has killed people exposed to sick poultry. This year, the United States saw its first death from bird flu, a Louisiana senior with a flock of backyard chickens.
Viruses are constantly evolving, and if a person catches bird flu while infected with a seasonal flu, the pathogens could mutate into a variant that infects large numbers of people. “The minute it transmits in humans, it’s done,” warned Erin Sorrell, senior scholar at the Johns Hopkins Center for Health Security.
Given the stakes — and the government’s limited investigation of this winter’s outbreak — ProPublica set out to examine the USDA’s continuing conviction that the spread of the virus can sufficiently be curbed by its safety practices.
To trace precisely how the virus rippled through more than 80 farms in the region, ProPublica analyzed data on the genetics of the virus, satellite imagery, wind simulations, property records and trade notices and consulted with researchers whose peer-reviewed work previously found that the virus can spread on floating feathers and particles of dust. (Read more about the effort here.)
ProPublica found that virus samples taken from outbreak sites shared a unique genetic signature.
Sources: National Oceanic and Atmospheric Administration, U.S. Department
of Agriculture, Darke County (Ohio) Auditor, Mercer County (Ohio) Auditor,
Jay County (Ind.) Assessor’s Office, National Poultry Improvement
Plan.
Our finding: The wind was at least a plausible explanation for how the virus could have spread from farm to farm.
We shared our analysis of the outbreak with eight experts in avian flu who agreed with that assessment. Several of them felt it was more than a mere possibility.
“It just seems so likely to me that this was an airborne thing,” said Brian McCluskey, former chief epidemiologist with USDA’s agency that oversees the response to bird flu. “I mean, how else would it have moved around so quickly?”
The experts stressed the analysis didn’t prove the wind directly carried bird flu from one farm to another, or that it was the only factor at play. The virus typically spreads via multiple routes, which could include contaminated birds, rodents or workers; if farms share the same feed supplier or trash collector, those factors can’t be ruled out.
But several experts said ProPublica’s analysis underscores the shortcomings of the government’s strategy, which fails to take the wind into account at all.
“USDA has been grossly negligent in not establishing risk factors in real time,” said Simon Shane, a poultry veterinarian and consultant.
Other nations have taken a different approach. After a devastating outbreak in France, researchers there discovered bird flu was traveling on dust and aerosols. France began vaccinating its ducks in 2023 and saw a near-total reduction in bird flu cases.
While American chickens are routinely vaccinated against all sorts of pathogens, USDA officials haven’t authorized similar efforts for bird flu, saying they could harm trade.
The agency is echoing arguments by the chicken meat industry, which outproduces and outlobbies the egg industry and has been far less impacted by bird flu.
The meat exporters and their congressional allies have long warned that vaccinating even just egg-laying chickens could cause other countries to block all imports of American poultry, deeming the entire country a bird flu risk. Trade agreements generally require a guarantee that imported poultry is free of bird flu, and some countries including the United States fear that vaccination might not fully prevent infections, allowing the virus to quietly spread among flocks and linger in meat.
Adding to the headwinds is U.S. Health and Human Services Secretary Robert F. Kennedy Jr., who has said the virus should be allowed to burn through flocks so that farmers can identify birds with natural immunity, an approach public health experts have called “dangerous and unethical.”
Rows of buried chickens killed in an effort to stamp out an outbreak of bird flu at a Weaver Eggs farm in Versailles, Ohio, in June Maddie McGarvey for ProPublica
A USDA spokesperson said it was “conjecture” to say vaccination would offer flocks better protection from airborne spread than its current strategy, which “remains rooted in real-time data, internationally recognized best practices and a commitment to transparency and continuous improvement.” The agency told ProPublica it has made no decision on whether to vaccinate hens and has no timeline on when it might announce one — though it is “proactively assessing” the possibility.
Avoiding the question of airborne spread appears to be in the USDA’s “best interests,” said Michelle Kromm, an animal health consultant who directed Jennie-O Turkey’s bird flu response in past outbreaks.
“If this is a major risk factor, then vaccine is absolutely a critical mitigation to put on the table,” she said. “And that, of course, is something USDA still is not, after a decade, prepared to do.”
The “Best Defense”
The United States faced a similar crisis a decade ago when bird flu hit over 200 Midwestern farms within the span of a few months. After genetic testing revealed that the virus had mostly spread from farm to farm, the USDA sought to determine how.
Epidemiologists looked for patterns among those hit by the virus and not, like whether vehicles had visited multiple farms or whether barns had easy-to-clean concrete entryways. Ultimately, no factor answered the question of whether a farm’s poultry would be infected as well as its proximity to a farm with infected poultry.
USDA scientists, including McCluskey, found virus spewing out of the exhaust fans on farms with infected birds and said more should be done to fully assess the risk of airborne spread. But because the USDA couldn’t determine exactly how the virus got into farms, it concluded it couldn’t say with certainty whether airborne transmission played a role.
The virus disappeared for years after that, but the government came up with a strategy to curb future outbreaks. It focused on keeping infectious materials from being carried onto farms using a method called biosecurity.
The USDA turned to the National Poultry Improvement Plan, a consortium of producers and government officials formed in the 1930s to combat the spread of a disease caused by salmonella. The group, which certifies poultry operators who take part in efforts to prevent disease in their flocks, developed guidelines for more uniform biosecurity practices, emphasizing concepts like “lines of separation” — areas where farmers would decontaminate before crossing and handling birds.
Biosecurity signs outside a Fortkamp Farms facility in Fort Recovery, Ohio, in May Maddie McGarvey for ProPublica
These protocols are now required for farmers who seek reimbursement for chickens they have to cull amid an outbreak. They are urged to seal holes in their barns to keep out wild birds, make sure they don’t track goose droppings on their shoes and be mindful that workers who travel through multiple farms can carry bird flu from one to another.
In 2022, a new strain of bird flu began infecting American flocks. About a year into the outbreak, officials noted a striking difference in their statistics: While farm-to-farm spread was responsible for 70% of the 2015 outbreaks, only 15% of cases originated from other farms. Industry and USDA officials concluded biosecurity was a resounding success.
But the government’s 15% statistic was not the big win for biosecurity that it suggested, ProPublica found.
Unlike the 2015 wave, which almost exclusively hit commercial farms, the majority of new infection sites were backyard or hobby farms raising just a few chickens, wide open to the threat of a new strain infecting a more diverse array of wild birds.
But hundreds of commercial farms were still hit by the virus this time around. And had the USDA published comparisons on those farms, a much different picture would have emerged. ProPublica obtained infection data from 2022, when bird flu arrived, through November 2023 (the period covered by a request under the Freedom of Information Act) and found that about 40% of infections on commercial premises were associated with genetically linked clusters. Despite a heavier emphasis on biosecurity, the disease was still moving among farms.
Since then, the threat to farms has gotten a good deal more complicated and the spread among them more significant.
The virus was discovered in dairy cattle in Texas and Kansas in March 2024 and has since been found in more than 1,000 cattle herds. That strain of the virus doesn’t appear to spread in the wild birds often blamed for circulating bird flu, USDA officials told ProPublica. Nevertheless, that strain, called B3.13, has somehow jumped to nearby poultry farms. Millions of birds have been killed after viruses matching those found in nearby dairies infiltrated their flocks.
Milk samples are tested for bird flu at Cornell University on Dec. 10, 2024, in Ithaca, New York. The strain of the virus infected over 1,000 dairy cattle herds, occasionally spilling over and infecting birds at nearby poultry farms. Michael M. Santiago/Getty Images
From then until late this summer, 73% of infections on poultry farms appeared to have originated on another farm. In spite of years of strengthening biosecurity, the nation’s farms were in the same place as they were a decade ago, when 70% of outbreaks stemmed from other farms.
“What does increased biosecurity do? After three years, it ain’t enough,” said Gail Hansen, a former Kansas state public health veterinarian and epidemiologist who now works as a veterinary consultant. “Why are we doing the same thing over and over again?”
The USDA prefers to look at the entire span of this wave — going all the way back to 2022 and including those backyard farms — to reiterate its position that the “overwhelming majority” of infections have been traced to contact with infected wild birds — not spread among farms. It said this winter’s outbreak was “not representative” and was “unique.”
A spokesperson also said that the “best defense” against indirect virus transmission of any kind is still “strong biosecurity.”
“Right in the Wind Direction”
Wild birds likely introduced the virus to Howe’s Hens outbreak in December, but that’s where their role ended. Every one of the farms that fell from that moment on was infected by another farm, the USDA confirmed. What’s in dispute is how.
Egg producers argued that biosecurity failures weren’t solely to blame for the millions of hens lost to the virus that season. “There are breeder farms out there that are considered to be bulletproof that this virus is finding its way inside somehow,” Oscar Garrison, United Egg Producers’ head of food safety, said at a USDA trade conference in February.
At the vast majority of egg farms, he said, infections started with chickens close to air inlets and on upper levels, far from where virus tracked in on shoes and clothes would end up. An Ohio egg farmer told ProPublica the same happened at their large facility; experts said such a pattern would likely emerge if the virus was spreading through the air.
The circumstances were ripe for it. A veterinarian with Cooper Farms, the company that runs or contracts with the majority of the poultry farms in the region, described how the process of killing huge flocks releases a mess of feathers into the air.
“We’ve had teams out there just picking feathers outside of these barns,” veterinarian Bethany Heitkamp said in February at the Ohio Pork Congress, an industry conference.
Infected carcasses tend to drop feathers — “and feathers, they stick to everything,” USDA poultry researcher Erica Spackman said at another industry forum. “They’re airborne on their own. So there’s a lot of opportunity for spread there.”
Widespread Chicken Deaths Forced Farmers to Dig Miles of Mass Graves
Aerial imagery over four western Ohio farms in March shows the toll of the virus’ impact on poultry stock after reports of infections in the region started in December.
A graphic containing a grid of satellite imagery, taken in March, of four western Ohio farms, where farmers buried between 245,000 and 1.8 million dead hens in dirt mounds on their properties.
Farmers culled and buried at
least 1.3 million hens under
dozens of dirt mounds
More than 931,000 hens buried
Jeff and Kyle
Fortkamp Poultry
About 245,000
hens buried
More than
1.8 million
hens buried
Farmers culled and buried
at least 1.3 million hens
under dozens of dirt mounds
More than 931,000 hens buried
Jeff and Kyle
Fortkamp Poultry
About 245,000 hens buried
More than
1.8 million
hens buried
Farmers culled and buried
at least 1.3 million hens
under dozens of dirt mounds
More than 931,000 hens buried
Jeff and Kyle
Fortkamp Poultry
About 245,000 hens buried
More than
1.8 million
hens buried
Farmers culled and buried
at least 1.3 million hens
under dozens of dirt mounds
More than 931,000 hens buried
More than
1.8 million
hens buried
Jeff and Kyle
Fortkamp Poultry
About 245,000
hens buried
Farmers culled and buried
at least 1.3 million hens
under dozens of dirt mounds
More than 931,000 hens buried
More than
1.8 million
hens buried
Jeff and Kyle
Fortkamp Poultry
About 245,000
hens buried
Note: Map scales vary due to zoom levels. Sources: Darke County auditor, ProPublica reporting.
After the virus spilled into nearby Indiana, the state’s head of avian health began to notice a pattern: If a farm had an outbreak and the wind was blowing hard that day, she could expect to hear news about another farm needing to test dead hens five to seven days later. “Then, what do you know, the lab calls, saying it’s positive,” Maria Cooper told members of the Board of Animal Health at a meeting that spring.
Cooper Farms declined to speak to ProPublica and instructed all of its contracted farmers to do the same. But in a recent episode of the industry podcast “Eggheads,” one of its employees described what it felt like to be in the thick of the outbreak.
Cole Luthman remembered fielding calls from poultry workers who had learned their neighboring farms had been infected. “Can I make it through it?” he recalled them asking. “And they’d be a half-mile down the road, basically right in the wind direction of the other farm that had just broken.” He told them to control what they could and that if they survived a week, they’d be okay. “And most of the farms would start seeing signs within seven days,” he said. “It was just devastating. Everybody felt helpless.”
As officials publicly pinned the blame on wild geese, rumors spread that drones hovering overhead were spraying the virus, perhaps controlled by foreign adversaries. Versions of the theory persisted long after authorities ruled it out.
“If you don’t fill the void with scientific information, people are going to fill the void,” said Kromm, the animal health consultant and former turkey industry executive. “This is people’s livelihoods, and the lack of the ability to use science that’s out there to at least make an attempt to help explain things to them is super frustrating.”
The USDA said it didn’t investigate whether airborne spread played a role in the outbreak. A spokesperson said the agency has explored wind in other cases but faced “significant challenges” that included “the inability to rule out other potential mechanisms of disease spread.”
Rather than investigating wind patterns, the USDA deployed a standard questionnaire asking farmers about who and what had come on and off the farm. The responses revealed “numerous movements” that the USDA said posed a risk of “indirect transmission.” The agency would not elaborate or provide more specific information, but noted that ProPublica’s analysis does not account for links “such as shared workers, equipment, or feed deliveries” that could have contributed to the spread.
“At this time, there is no compelling evidence that indicates aerial transmission poses a greater risk than other known transmission routes,” said a USDA spokesperson.
Studies continue to support the theory that the wind is carrying the virus from farm to farm. Research in France that helped prompt policymakers to vaccinate flocks found dust laden with virus that came from infected farms. More recent work has established the density of farms as a key risk of viral spread in France’s duck-farming regions, which authors said “suggests that contaminated dust or feathers could reach neighbouring farms.”
Perhaps the strongest evidence comes from the Czech Republic, where earlier this year a team of scientists mapped the spread of the virus from a duck farm to two “high-biosecurity” chicken farms 5 miles away. They used genomic and meteorological information to show that “wind was the most probable mechanism of infection transmission.”
Alexander Nagy, the Czech researcher who led the study, was among the experts with whom ProPublica discussed our analysis of the Midwestern outbreak. Nagy said the data assembled by ProPublica “strongly suggests that wind may have played a significant role in facilitating viral spread between farms” as it had in the cluster he investigated.
“The Only Way to Get Past It”
Rows of buried chickens outside a poultry farm in Fort Recovery, Ohio, in May Maddie McGarvey for ProPublica
As hens died in record numbers in February, Tony Wesner, CEO of Rose Acre Farms, spoke to Congress about the difference vaccines had made against other scourges.
“If you look at diseases that we have had in the poultry industry in the past, the only way to get past it was through vaccine,” he said. “We have to control this disease. We have to do it with offense, not defense, which in my opinion is what we have done to this point.”
The government has had a proven poultry vaccine against this strain of the bird flu since July 2023, when USDA scientists concluded several available vaccines provided full protection against death and illness and reduced the shedding of virus in infected chickens. Trade has been among the biggest barriers to using it.
As the egg industry asked newly minted Agriculture Secretary Brooke Rollins to “bring a new sense of urgency” to address the question of vaccination, a bipartisan group of lawmakers wrote to her on behalf of the chicken meat industry, warning of a $10 billion economic loss if USDA authorized a vaccine. “If an egg-laying hen in Michigan is vaccinated,” they wrote, “the U.S. right now would likely be unable to export an unvaccinated broiler chicken from Mississippi.”
The scenario isn’t farfetched. After France vaccinated its ducks, the U.S. paused all poultry imports from the European Union, deeming much of the continent a risk because the vaccine could mask the presence of bird flu. The main way the virus is detected is by noticing dead birds; if vaccinated birds get infected but don’t die, the logic goes, how would anyone know whether the virus is spreading?
A car wash used as part of biosecurity measures at the North Arlington Processing complex in Arlington, Arizona Maddie McGarvey for ProPublica
That’s not a risk the chicken meat industry is willing to take; it has lost only a tiny share of its chickens to bird flu and wouldn’t have a practical way to vaccinate them anyway. While egg-laying chickens are often in production for at least two years, broiler chickens are slaughtered within two months.
Wesner, the egg company CEO, argued that a large share of exported chicken meat went to countries that already vaccinate against bird flu. “I cannot understand why we cannot get together with those countries and figure this out so we do not ruin trade,” he said.
Vaccine proponents were heartened early in the Trump administration when the USDA licensed a chicken vaccine developed by Zoetis. But soon after, in an interview with Breitbart News, Rollins dashed their hopes that it would be used any time soon.
“It seems like a very simple and easy and quick answer but ultimately the repercussions that we don’t fully understand could be so significant that we just have to go in a different direction,” she said. “We have a tremendous amount of work to do before we would even consider that as a potential solution and that is at least a year or more away.”
She said she’d spoken with Nebraska Gov. Jim Pillen, who is a veterinarian: “He said to me, ‘Brooke, don’t ever forget, the virus always wins.’”
Pillen said in a March interview that vaccines would still allow the virus to spread and mutate, posing a threat for the disease to spread to people. “Using a vaccine would be absolutely catastrophic because there’s no vaccine that’s effective,” he said.
Kennedy echoed the sentiment in an interview with Fox News’ Sean Hannity, saying that vaccination would turn flocks into “mutation factories.”
Experts in avian influenza say the opposite is true. Not vaccinating poultry means that the virus has more opportunities to infect humans and adapt, said Richard Webby, an influenza researcher at St. Jude Children’s Research Hospital. “These are the interfaces where we know transmission occurs,” he said of poultry farms.
And while it isn’t guaranteed to prevent all infections, vaccination makes them much less likely and lowers the chances that they will spread because the birds wouldn’t shed as much virus, said David Swayne, the former head of the USDA’s poultry research unit. “It makes the chickens or turkeys very, very resistant to infection.”
Swayne helped the egg industry craft a vaccination plan, which would include testing vaccinated birds to ensure the virus isn’t spreading undetected. Such surveillance is essential, said Jean-Luc Guérin, one of the researchers who helped convince French officials to vaccinate the country’s ducks. It has been more cost-effective, too; vaccinating and regularly testing the ducks cost $120 million after the first year, compared with the $1.6 billion the disease response cost in the outbreaks in 2021 and 2022. The government and industry are sharing the cost.
Two people cradle a small yellow duckling while it is injected with a metal device attached to a white tube. Gaizka Iroz/AFP/Getty Images
After France showed the surveillance strategy worked, the USDA resumed poultry imports from the European Union in January.
But USDA is in no rush to copy it. “Any potential vaccination strategy must account for complex logistical challenges — including administration, expanded surveillance, and associated costs — that must be carefully evaluated alongside scientific considerations,” a spokesperson told ProPublica. The agency says it is supporting research on “advanced vaccines to reduce transmission, protect poultry and stabilize food prices” and notes on its website that it is assessing “promising candidates in coordination with HHS,” Kennedy’s agency.
“We recognize there are multiple stakeholders,” said Garrison of United Egg Producers, “and those conversations are ongoing.”
Glenn Hickman, whose Arizona egg operation has lost over 6 million birds to the disease over the last 12 months, is losing patience. As he begins to move a new group of young hens into a layer barn, he fears he can’t fully protect them. “It’s terrifying because, again, we haven’t vaccinated, so nothing’s different,” he said. “If it was just that there’s no cure, then, OK, it’s just your luck of the draw. But the fact is that there’s a tool in our toolbox that’s affordable, available, and we can’t use it.”
Glenn Hickman at his farm in Arlington, Arizona Maddie McGarvey for ProPublica
It would cost $33 million to vaccinate in America’s turkey and egg industries, according to Jada Thompson, an agricultural economist at the University of Arkansas who worked on a report for the USDA. Rollins has committed to spending up to $500 million on audits of farms’ biosecurity and special inspections to examine where wild birds might be infiltrating farms, with some money to “fix the highest risk biosecurity concerns,” $100 million for research that could involve vaccines and another $400 million to keep reimbursing farmers for birds they have to kill. The government has already spent well over $1 billion on such reimbursements since 2022.
Experts told ProPublica they believe that decision-makers at the USDA are just stalling in hopes that the virus fizzles out, as it did a decade ago.
“I think their inability and unwillingness to do this stems from a disbelief that this is something that they are going to have to deal with over the long term,” said Jennifer Nuzzo, director of the Pandemic Center at the Brown University School of Public Health. “I think they’re hoping that this just goes away.”
Around this time last year, at the start of a new bird flu season, only 26 commercial poultry farms had been struck. This fall, however, 78 have already fallen.
Hickman walks through his empty chicken barns in Arlington, Arizona, in September, after a bird flu outbreak earlier this year wiped out about 6 million birds. Maddie McGarvey for ProPublica
