Bird Flu Update 2025 –Backyard Flock Keepers’ FAQ’s — Randy’s Chicken Blog

By the 1950s, mass bird deaths from fowl plague were being reported globally. In 1957, another human flu pandemic killed over a million people, raising suspicions of a bird-human virus link. When another human pandemic hit in 1968, better lab tools confirmed the connection. In 1981, scientists gathered for the First International Symposium on Avian Influenza and decided that it was time to call fowl plague what it really was: Avian Influenza. Bird Flu.

Today, bird flu viruses are classified as either low-pathogenic (LPAI) or highly pathogenic (HPAI). LPAI strains circulate constantly in wild birds. In backyard flocks, they might go unnoticed or cause only mild symptoms like ruffled feathers or fewer eggs. HPAI is far more dangerous. It spreads fast, causes severe illness, and can wipe out an entire flock. Alarmingly, LPAI can mutate into HPAI.

The current dominant strain—H5N1 clade 2.3.4.4b—was first detected in wild birds in the U.S. in the Carolinas in December 2021, and then in Indiana poultry in February 2022. Since then, it has spread across the U.S. It’s one seriously nasty virus.

When bird flu strikes poultry flocks, U.S. animal health experts follow a tried-and-true strategy developed during past outbreaks. This approach has consistently helped contain the disease. There are six main strategies:

Biosecurity: Wild birds are the main carriers of avian flu. To reduce the risk of the virus spreading to poultry, the USDA inspects farms to find and fix potential points of contact with wild birds. They also perform biosecurity audits and often help pay for needed improvements.

Monitoring: To catch outbreaks early, the USDA tests both poultry and wild birds. In 2022, they ran more than 1.8 million tests on poultry and collected nearly 21,000 samples from wild birds.

Quarantine:  If bird flu is detected, a control zone is established around the infected site. Movement of poultry and poultry equipment in and out of the area is strictly limited.

Depopulation:  All poultry within the control zone are euthanized.

Disinfection:  After depopulation, each facility is thoroughly disinfected.

Testing:  After disinfection, each facility is rigorously scanned for the presence of the bird flu virus.

This protocol has been the backbone of the U.S. response to avian flu in poultry for decades.

When clade 2.3.4.4b emerged in early 2022, the U.S. already had strong prevention and control measures in place. As always, officials responded swiftly—using surveillance, biosecurity, quarantine, culling, and disinfection. But despite these efforts, the virus kept spreading. Why?

There’s no simple answer. Experts have some ideas, but much of it is still speculation. Here’s what might be going wrong:

New Hosts and New Routes of Transmission

Clade 2.3.4.4b is proving unusually adaptable. In the past, avian flu mostly spread through certain migratory waterfowl. Now, this strain is infecting a much wider range of birds, including cormorants, pelicans, vultures, hawks, and falcons. This expansion makes the virus harder to monitor and control.
As University of New South Wales epidemiologist Raina MacIntyre puts it: “We’ve got to think beyond ducks, geese, and swans. They’re still important, but we have to start looking closely at these other species and other routes and think about what new risks that brings.” Many of these new bird hosts show few or no symptoms, which means the virus can spread silently.

The virus isn’t just spreading through birds. It has also jumped to more than 80 species of mammals. The ABC’s of infected mammals include alpacas, bears, and cats, then goes on to include dolphins, elephant seals, fishers, goats, and a whole host of others. You can see the full list here. There is strong evidence of mammal-to-mammal transmission among wild sea mammals such as sea lions, marine otters, porpoises and dolphins. And there is one proven case of direct mammal to mammal spread at a Spanish mink farm where over 50,000 mink were eventually euthanized. Direct mammal-to-mammal spread is alarming because such transmission could bring the virus a step closer to human-to-human transmission and an ensuing pandemic.

Its adaption to new mammal hosts also allows new transmission pathways. For instance, its infection of dairy cows has allowed transmission through milk.

Surveillance Weaknesses

While the USDA offers biosecurity and testing programs for poultry and livestock farms, participation is voluntary. Many farms opt out, leaving large parts of the country essentially unmonitored.

As the virus spreads into cattle, current rules haven’t kept up. Milk testing only started recently. With poor data and gaps in testing, it is likely that officials are underestimating the true scale of the outbreak.

Monitoring wild birds presents an even bigger challenge. Monitoring the virus in one or two wild bird species is challenging. Monitoring it in multiple species is impractical to impossible.

A Slow Response to A Rapidly Changing Virus

Flu viruses are successful because they can evolve and adapt quickly. Government responses typically evolve and adapt glacially. Updating official strategies can take months of bureaucratic review and political debate. By the time a new policy is approved, the virus may have already evolved again. In short: the virus is nimble. The response is not.

Factory Farms

Modern industrial farms cram thousands of animals into confined, often unsanitary spaces. This creates ideal conditions for viruses to mutate and spread.

The Humane League (THL) argued in June 2024 that many livestock diseases could be reduced by moving away from intensive confinement. THL president, veterinarian Vicky Bond, put it bluntly: We’ve created a system “in which thousands of animals are packed into dense, unclean living quarters—creating conditions ripe for disease…The threat remains high unless we collectively change our relationship with nonhuman animals.”

Science writer David Quammen echoed the THL statement in this 2024 New York Times essay, calling factory farms “petri dishes for the evolution of novel pathogens.” With so many animals raised in such close quarters, he argued, it’s no wonder new viruses are emerging and spreading to humans.

Bottom Line

The old playbook isn’t enough anymore. The virus has changed. The environment has changed. And without stronger surveillance, faster responses, and rethinking how we raise animals, avian flu may continue to outpace our efforts to stop it.

In response to the ongoing bird flu crisis, the new administration announced a fresh strategy in early 2025. On February 26, the U.S. Department of Agriculture (USDA) released a statement titled “USDA Invests Up to $1 Billion to Combat Avian Flu and Reduce Egg Prices.” In the release, USDA Secretary Brooke Rollins introduced a new five-pronged approach to fight the virus and stabilize the egg market. The five prongs: