Mass Killings of American Poultry

Where are these data from?

Confirmed detections of bird flu in poultry are tracked by the United States Department of Agriculture (USDA).

What are the symptoms?

Bird flu is a terrible disease, especially for chickens. Infected birds can have symptoms like low energy; lack of coordination and appetite; coughing and sneezing; discoloration and swelling of face, legs, feet, wattles and combs; diarrhea; trouble laying eggs; and sudden death.

Domesticated turkeys, ducks, and chickens all die alarmingly quickly, often just 2-3 days after first showing symptoms. Geese can sometimes survive. The mortality rate is high, and 75–100% of infected chickens die. (1, 2, 3, 4, 5, 6).

How is bird flu spread?

Bird flu is spread through bird fluids, mostly their snot and feces. The coughing, sneezing, and diarrhea help it move between birds, especially in close quarters.

In liquid, like a shared watering trough or an outdoor pond, the virus has an incredible survival rate of nearly a month at 80°F. In cold water, it can survive up to five months, and if it’s frozen it can survive indefinitely. It’s not great in direct sunlight, but it’s been shown to still be actively contagious in chicken feces held at 90°F for four days.

Wild birds, mostly waterfowl, are carriers of bird flu but typically don’t die from it. Areas along bird migration flyways are at particular risk of infection, especially in the spring and autumn.

Even dead chickens remain contagious for weeks, and the USDA recommends burial, incineration, or industrial composting of the carcasses.

Is there a cure or a treatment after poultry gets infected?

No, there is not.

Is there a vaccine?

Yes.

mRNA vaccines have been tested on common egg-laying chicken breeds and they keep birds alive with a high rate of success. In February 2025, vaccine manufacturer Zoetis was granted a conditional license in the U.S., which would allow their bird flu vaccine to be deployed in an emergency. The EU granted authorization to Merck for a single dose, one-time vaccine that guards against bird flu as well as two other highly contagious high mortality scourges: Marek’s disease and Newcastle disease. The EU, Mexico, Ecuador, and China all have domestic vaccination programs for their poultry.

Why doesn’t the U.S. use a vaccine?

The U.S. and Brazil have so far resisted using a vaccine domestically because of international trade agreements.

Many countries, including the U.S., do not allow imports of poultry from countries that allow vaccination. In fact, the U.S. barred the import of all poultry from France in 2023 because of its decision to vaccinate just their meat ducks against bird flu. The justification for these bans is that vaccinated animals can reduce symptoms thereby masking the presence of bird flu. And asymptomatic live birds could bring variants of the bird flu to domestic flocks. Of course, it’s already here. The wholesale ban on French poultry was slightly relaxed in 2025 to allow some unvaccinated poultry imports.

Without updated trade agreements, the U.S. is worried about similar bans being enacted on its broiler chicken exports — a $5 billion dollar industry which is vehemently opposed to a vaccine — if it vaccinates any portion of its poultry, namely its egg-laying hens.

There are two other factors that are commonly cited. First, some economists think that vaccinating the entire U.S. poultry flock might be too labor intensive for chicken farmers (comments and articles written by egg farmers do not agree; they are asking for a vaccine). Second, bird flu mutates quickly, so there is a chance that highly-targeted bird flu vaccines may quickly go out of date. After the 2014–2015 bird flu outbreak, the U.S. government built a national stockpile of poultry vaccines, but by 2016 it was found to be not “well matched” to the variants in circulation.

What happens to a farm when their flock shows symptoms?

Because of the issues with implementing vaccines, the U.S. government has followed a policy of stamping out. When a bird flu outbreak is reported, the government designates an infected zone and immediately slaughters animals in the potentially-infected area. Then there’s a long process of carcass disposal and disinfection.

To promote the strategy, the government pays farmers to destroy their potentially-infected flocks as soon as any portion of the flock shows symptoms. In fact, farmers don’t get paid anything for birds killed by the disease, only for the living birds that must be “depopulated.” Given the mortality rate and short window before all their birds are dead anyway, farmers have to act quickly if they want to be reimbursed for their flocks.

Counting from the beginning of the 2022 bird flu outbreak, indemnity payments to poultry farmers have reached $1.1 billion dollars. To put that in perspective, an industry-supported website calculates that the U.S. poultry industry and its workers cumulatively pay about $33 billion dollars in federal taxes.

Farmers that grow broiler chickens may also get losses covered by the corporations that supply them, and there is, of course, insurance.

What can poultry farms do?

Because they’re not allowed to vaccinate, chicken farmers are only left with increasing their biosecurity measures.

First, they can try to prevent any interactions between their flock and wild birds. That includes limiting access to any outdoor food or water sources, securing barns against stealthy birds looking for food, etc.

Second, they can stop bird flu from coming in via equipment, which is not always easy or appreciated. Darke County, Ohio has 18 egg farms in a 20-minute radius. They’ve had to deal with 25 outbreaks of bird flu and had almost 10 million poultry killed. Yet the farms also have a number of one-star google reviews from truck drivers, who complained because they had to provide receipts showing that they had their tractor-trailer washed and disinfected before entering the farm. Washing and disinfecting trucks is one of the most basic biosecurity measures farms can take (1, 2, 3), and spread of the flu between farms by trucks was a major factor in the 2014-2015 H5N2 outbreak.

Are some breeds of poultry more resistant to bird flu?

Maybe.

The U.S. egg industry relies heavily on one breed of chicken — the white leghorn. They’re hardy, they lay a lot of eggs relative to the amount of food they eat, and they start laying young. White Leghorns are also particularly susceptible to bird flu.

Other breeds may be more resistant, but the popularity of the leghorn in America means that other breeds haven’t been tested at scale. Moving the commercial egg industry to a different breed of chicken, with different laying cycles and feed requirements would likely require a large shift, and the benefits are so far unknown.

Are free-range chickens in more danger?

Yes, but the death counts are not clear cut.

Cage-free is a USDA label that farmers can apply to their eggs if they attest that their chickens are free to move around a secured chicken house. Free-range is a subset of cage-free, and the chickens must have access to the outdoors, particularly while they are laying. But they are not forced to go outside, and their outside area can be secured by fences and nets.

The USDA doesn’t specifically track bird flu deaths of chickens raised in a free-range environment, only of the broader cage-free category. In 2024, 17% of the cage-free flock was killed by bird flu, whereas only 6% of the caged flock was lost. But, in 2025, bird flu has killed 11% of both the cage-free and caged flocks.

Are bird flu, HPAI, and H5N1 all the same?

No, but these terms are used interchangeably in many contexts.

Bird flu (a.k.a. “avian influenza”) is a broad term that refers to the Influenza A virus species. H5N1 is a subtype of Influenza A named for two protein components on its surface. Because the same two proteins can be found on multiple genetic variants, H5N1 is not a unique name.

Highly Pathogenic Avian Influenza (HPAI) is a classification system that describes a virus as killing more than 75% of the chickens it infects. If the variant kills less than 75% of infected chickens, it’s described as Low Pathogenic Avian Influenza (LPAI). There are both HPAI and LPAI versions of H5N1 viruses.

For this work, I use the broad colloquial term “bird flu” to describe the current, wide-ranging epidemic of HPAI H5N1 that began in February, 2022.

Why is that one area in the Midwest getting hit so often?

The area between the Mississippi and Missouri Rivers centered roughly on Sioux Falls, South Dakota is called the Prairie Pothole Region.

During the last ice age, the retreat of the Laurentide Ice Sheet left behind thousands of shallow lakes and waterways there. Today, it’s a mix of grasslands and prairie coteau, and despite the fact that large tracts have been drained for cropland, it’s still a prime spot for the breeding and nesting for millions of waterfowl.

It’s also filled with commercial poultry farms, perhaps because of access to nearby grain farms. The combination of wild waterfowl carrying bird flu and susceptible domesticated poultry has not been good for the farmers there.

What’s happening now?

Agricultural Secretary Collins issued a press release saying she would expand Biden-era “Wildlife Biosecurity Assessments” to give advice to farmers on how to secure their chickens against wild bird interactions, provide additional payments to farmers that have to destroy their flock, “deregulate” by regulating California’s regulations, and put $100 million towards vaccine development.

Farmers were gracious, with hints of skepticism.

What’s the end game?

For many years, the USDA’s strategy has been to hunker down, seal up the barns, and hope bird flu mutates into something less deadly within the wild bird population.

Other bird flu epidemics have killed birds and then faded away. The last one, in 2014–2015, killed 50 million chickens and turkeys before abating. The current epidemic has lasted twice as long, killed three times as many poultry, and continues to grow. Many experts think that real success in protecting domestic poultry involves a bird-flu vaccine.

“Unless something changes, the specter of bird flu’s devastation will hang over the United States indefinitely — as will the threat of other emerging diseases.” Maryn McKenna, a public health and food policy journalist.