Commonly known as bird flu, the H5N1 avian influenza virus is found in wild aquatic birds across the globe and can also cause outbreaks and disease in poultry.
S. Mark Tompkins heads UGA’s Center for Influenza Disease and Emergence Research, one of only six such institutions focusing on the history, transmission and progression of influenza nationwide funded by the National Institute of Allergy and Infectious Diseases. His lab is currently one of five institutions working with the FDA to test U.S. dairy supplies for avian influenza.
What should people know about the most recent bird flu outbreak?
Avian influenza is common in wild birds. These viruses circulate globally in migratory birds without making the birds sick. What’s less common is for strains of the virus to jump species and cause severe disease in other animals such as poultry.
Many animals are susceptible to infection with the H5N1 avian influenza strain, but the high number of infections and animal deaths are concerning. Large numbers of mammals are being infected and dying from the virus, including bears, foxes and even a dolphin. And the extensive spread of H5N1 on U.S. dairy farms is particularly worrisome. We have never seen levels this high before.
The spread of the virus has also resulted in more human infections. But there has only been one severe case to date. And the risk to humans remains very low.
Could the bird flu become a pandemic?
In short, we don’t know.
The number of infections in so many species provides the opportunity for the virus to potentially adapt and more efficiently spread among humans.
The CDC has only detected 61 human cases since the start of the H5N1 outbreak.
Although the risk of an avian influenza pandemic is very low, I will never say never. It is very important that we take measures to reduce the risk of exposure to not give the virus the chance to adapt to humans.
Is it safe to drink milk during a bird flu outbreak?
Yes — if you are drinking pasteurized milk. Studies have shown that pasteurization of dairy products kills the virus, along with many other disease-causing pathogens.
However, raw dairy products may contain live H5N1 virus or other pathogens, such as salmonella and listeria, that can infect people and result in severe disease.
Consuming raw dairy products is never recommended.
Why was a state of emergency declared over bird flu?
California is the largest dairy producing state in the U.S., and the state had already implemented the largest testing program in the U.S. along with other control measures. With the unprecedented spread and risk to humans, the dairy industry and the nation’s food supply, the governor of California declared a State of Emergency to enable additional resources, personnel and regulatory tools to respond to the avian influenza outbreak.
Since first being detected on California dairy farms in August 2024, H5N1 has been detected in 645 dairies. Two companies also issued recalls after detecting H5N1 in their raw dairy products.
What are the symptoms of bird flu in people?
It varies.
Most cases present as red, irritated eyes, sometimes with discharge. Without government surveillance efforts, we may not have known these infections were caused by avian influenza.
Others experience flu-like symptoms, including:
- cough,
- sore throat,
- headache,
- runny or stuffy nose,
- fever,
- muscle or body aches,
- diarrhea
- and/or fatigue.
But you could also be infected without symptoms. That’s why it’s hard to know how many mild or asymptomatic avian influenza infections happen each year.
A few cases have resulted in more severe flu-like symptoms with shortness of breath or seizures. But this is incredibly uncommon.
Many viral infections including the common cold, RSV and coronavirus cause similar symptoms to avian influenza, though. And these diseases are all circulating during cold and flu season.
How severe is bird flu in humans?
So far, there has only been one case of severe disease in the U.S.
That individual was directly exposed to H5N1 from sick and dead birds in backyard poultry flocks.
There have been 60 other confirmed human infections in the U.S., all without severe disease.
Globally, there have been four additional severe cases related to the virus circulating in dairy cows.
How does bird flu spread?
This is a bit of a complicated question.
Our normal seasonal flu is spread through the air when infected people cough and sneeze.
Avian influenza is different.
Current studies suggest H5N1 does not spread well through the air. This makes it different from the typical human flu and is one of several reasons why the risk of a bird flu pandemic remains low.
Almost all of the human cases of H5N1 were in people with high exposure to infected or dead animals, such as workers on dairy or poultry farms.
These individuals were likely infected after getting the virus on their hands and rubbing their eyes or by breathing in high quantities of the virus.
Most wild animals contract the virus by eating infected or dead birds. And we believe avian influenza is being spread among dairy cattle through the milking process in commercial dairies.