November 29, 2025 · View in browser

My reporting confirmed my hunch that they were linked: After the first farm was infected, the virus spread from that site to others, moving from farm to farm in a way that revealed a major flaw in America’s strategy to combat bird flu.

The culmination of that reporting became the investigation we published this month, “What the U.S. Government Is Dismissing That Could Seed a Bird Flu Pandemic.” It explains how the federal government is failing to control the spread of a deadly virus that could spark a pandemic.

The U.S. Department of Agriculture typically attributes bird flu outbreaks to failures of biosecurity — meaning farmers have not done enough to protect flocks from contamination by wild birds.

But my genomic analysis shows wild birds had little to do with this particular cluster of infections. Although the USDA said it tested nearly 1,000 virus samples in wild animals from December to April in Ohio and Indiana, no nearby wild birds were found infected with this outbreak’s strain. 

I did find a strong predictor of infection during the first few weeks of this outbreak: whether a farm was downwind from that first contaminated facility. That pattern reinforced the suspicions of egg producers and some local officials that the virus may be spreading on the wind. 

If bird flu is airborne, the government’s current biosecurity-based strategy cannot protect farms on its own. A poultry vaccine likely would have stemmed the damage from this outbreak, experts told me. Yet while other countries have curbed infections through vaccination, the U.S. has not authorized those efforts amid political and economic pushback.

The USDA told me it didn’t investigate whether the wind contributed to the outbreak’s spread. 

In my post on propublica.org, I explain how I used genetic markers, satellite imagery, property records, trade notices, wind simulations and Google Street View to do the work USDA did not. I encourage you to read that for a full accounting.

When I discussed my analysis with experts, many were pretty aligned in saying none of what I had found definitively proves that the wind caused the virus to spread; there’s a difference between correlation and causation, and the virus never follows just one mode of transmission. 

“It’s hard, it’s really hard — having spent my career studying viruses that spread through the air — to prove that the virus is in the air,” said Seema Lakdawala, who studies the epidemiology of influenza viruses at Emory University. “Yes, the wind might be important, but it may be other things that are moving in the wind, maybe the bugs, some other sort of vector moving along the wind that we have not accounted for.”

Nevertheless, other experts I discussed our analysis with — eight in total — agreed that this data presented a plausible case for the wind playing a role in this outbreak.

“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?”

Yang Zhao, an engineer and animal scientist at the University of Tennessee Institute of Agriculture, said that ProPublica “definitely moved one step further from our research in the past.”

“This result is very exciting, very interesting to me,” he said.

The USDA insisted that this particular outbreak was “unique” and “not representative” of the entire wave of bird flu that started in 2022, and that the “overwhelming majority” of infections stem from wild birds. The agency said its biosecurity strategy “remains rooted in real-time data, internationally recognized best practices and a commitment to transparency and continuous improvement,” and that it is “proactively assessing” the possibility of vaccinating poultry for bird flu. 

“At this time, there is no compelling evidence that indicates aerial transmission poses a greater risk than other known transmission routes,” a spokesperson told me.

Experts told me that understanding what drove this massive outbreak was important, and it didn’t seem like USDA was doing that work. The agency did not evaluate airborne transmission in this outbreak. It also doesn’t make it easy for others to do so, withholding key information that would allow journalists and researchers to evaluate the spread of the virus. 

As infections surge again this fall, the USDA continues to urge farmers to improve biosecurity while it dismisses a significant way the virus could be spreading.

Egg producers suspect bird flu is traveling through the air. After a disastrous Midwestern outbreak early this year, we tested that theory and found that where the wind blew, the virus followed. Vaccines could help, but the USDA hasn’t approved them.

Was this email forwarded to you from a friend? Subscribe.

This email was sent to npy7hz0ktx@niepodam.pl.