The bird flu that has been growing more pervasive during the last few years has infected more than 500 species, including 485 avian and at least 70 mammal.
The outbreak is being described as the fastest spreading and largest ever, posing a significant threat to biodiversity worldwide.
The avian invader is pushing the boundaries of what we thought we knew about animal diseases.
The highly transmissible bird flu, also known as H5N1, has been sweeping across the United States leaving a trail of dead chickens and empty egg cartons, and worried public health officials.
The virus has infected over 138 million birds across all 50 states and Puerto Rico, and spread to millions more on five more continents.
What started as a typical bird flu outbreak four years ago has evolved into a cross-species threat that's ruffling far more than feathers.
As 2025 gets underway, the avian flu is ramping up. Jumping species. Dolphins and polar bears have it. So do smaller mammals such as wild foxes, skunks, and seals, leaving many dead or with neurological symptoms.
The progression of the bird flu in America since 2021 has been unprecedented, including the first-ever cases of infections in dairy cattle and raising heightened pandemic risks.
Chris Walzer is the Wildlife Conservation Society’s director of health and a board-certified veterinarian who has been warning of avian influenza’s devastating and worldwide impact on wildlife for more than a year.
He is also a professor of conservation medicine at the University of Veterinary Medicine in Vienna, and said bird flu is highly transmissible, spread through droplet and feces-borne infections, and exacerbated by climate-change-altering migration schedules for birds and its circulation, again and again, through domestic poultry.
“The bird flu outbreak is the worst globally and also in U.S. history, with hundreds of million birds dead since it first turned up in domestic waterfowl in China in 1996,” Walzer said in a statement one year ago. “H5N1 now presents an existential threat to the world’s biodiversity."
'A nightmare'
For the poultry industry, it's been a nightmare. Bird flu has wiped out entire flocks of egg-laying hens – and bears, coyotes, cows, and raccoons.
On January 17, Georgia confirmed its first H5N1 avian flu outbreak at a commercial farm. The spread occurred at a broiler farm housing 45,500 birds in Elbert County, located in the northeastern part of the state.
This event is particularly significant because Georgia is the nation's leading state for chicken production. In response, Georgia officials implemented a ban on poultry exhibits, including sales of live birds at markets and other gatherings featuring live birds.
Rose Acre Farms, the nation's second-largest egg producer, this week confirmed an avian flu outbreak at its facility in Seymour, Indiana, with 2.8 million birds, sure to further strain the already tight egg supply.
The widespread losses in bird populations are expected to have a substantial impact on egg prices. Predictions indicate that egg prices may reach record highs later this year.
Earlier this month, consumers were already encountering vacant shelves and escalating prices for eggs in grocery stores across the nation.
Each time a flock of egg-laying hens has been wiped out, farmers must scramble for new chicks. The result? Empty shelves and sky-high prices at the grocery store.
Your morning omelet might soon require a small loan.
'Unprecedented'
The virus is showing an alarming ability to jump species. In 2023, it made its Arctic debut, claiming a polar bear in Alaska. It's now been found in at least 48 mammal species, many of which had never been diagnosed with avian influenza before.
The bird flu primarily hitches a ride with migratory birds, especially ducks and geese. These frequent flyers serve as nature's own viral delivery service, spreading H5N1 across vast distances during their seasonal travels
"This is an unprecedented situation," said Nichola Hill, an infectious disease ecologist at the University of Massachusetts Boston. "We've never seen a bird flu virus persist in wild birds for this long or spread this widely."
The virus poses a threat not only to poultry but also to various animals, including household pets, who like other animals can become infected by consuming contaminated birds or through exposure to infected environments.
The best way to prevent your pets from catching bird flu is to minimize the risk of being infected by it. To do that, health authorities recommend:
• Avoid contact with sick or deceased birds or animals
• Refrain from consuming raw milk or meat
• Do not feed pets raw or contaminated food
• Backyard bird enthusiasts should wear gloves and disinfect bird feeders
• Keep pets away from wild animals
Cats, in particular, are susceptible to H5N1. They can contract the virus by snacking on infected birds or hanging out in contaminated environments. Dogs aren't off the hook either, though they seem less likely to catch it than their feline counterparts.
The fatality rate for the current strain of H5N1 in cats hovers around 67%.
That's enough to make any cat owner think twice about letting Fluffy roam free.
Spread to humans
As of this month, ‘67 human cases of H5N1 bird flu have been reported in the United States. One man died.
Despite those numbers the current risk to public health remains low, but health officials are closely monitoring the situation due to the virus's ability to infect mammals, including humans.
Job-related or recreational exposure to infected birds increases the risk of human infection. People at higher risk include farmers, poultry workers, backyard flock owners, animal care workers, and public health responders.
The scientific community remains vigilant about the potential for the H5N1 virus to mutate and acquire the ability to spread efficiently between humans, which could potentially lead to a pandemic. Similar outbreaks in Europe and North America underscore recurring risks driven by migratory pathways, with ongoing viral evolution and reassortment leading to over 100 genotypes.
Each new infection gives the virus an opportunity to randomly mutate as it replicates, and if different strains of the virus infect a new host simultaneously, there is a risk of Patient Zero.
The Centers for Disease Control and Prevention and other health agencies are closely monitoring the situation, tracking factors such as virus transmission patterns, disease severity, case distribution, and genetic changes in the virus.
The bird flu outbreak is so devastating it has caused billions of dollars in losses in America alone from poultry culling and decreases in agricultural productivity, and it has renewed calls for vaccination strategies and improved biosecurity worldwide.
The virus has evolved so many times and jumped dozens of species it has researchers in several peer-reviewed journals, such as the Journal of the American Veterinary Medical Association, Emerging Infection Diseases, and Emerging Microbes and Infections, warning that the scientific community has to stay abreast of any mutations and share all the information possible to ensure a future version does not set into humans and become the next global pandemic.
The virus is reshaping ecosystems, affecting everything from endangered species to entire food chains.
It's a stark reminder of the delicate balance of nature and how easily it can be disrupted, as it was during the height of the COVID pandemic.
Nobody wants to see what that might look like.
Environmental reporting for WGCU is funded in part by VoLo Foundation, a non-profit with a mission to accelerate change and global impact by supporting science-based climate solutions, enhancing education, and improving health.
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