What to Know About Bird Flu, or Avian Influenza


It began in early 2022, but a record spread of bird flu outbreaks, which have affected more than 57 million birds, remains ongoing in the US in 2023, affecting egg prices and requiring farmers to kill healthy birds in sick flocks

Though the health risk to the general public remains low, people who work with birds, or live with them as pets, should take extra precautions to “avoid unprotected contact” with any birds that look sick, the US Centers for Disease Control and Prevention said in a November update on the record-breaking illness. This includes wearing personal protective equipment like rubber boots and a face mask if working with them, and washing your clothes and hands after handling birds.

As long as animals and humans live, work and gather around each other, there will be a risk of viruses mutating enough to make the jump from species to species. Fortunately, bird flu in humans so far has been rare (the current outbreak is limited to one human case in the US), in part because the virus doesn’t spread that easily from animals to humans, or between humans. This is why risk of bird flu is considered higher for people who work directly with birds, such as poultry workers or even hunters.

Still, some “sporadic” human cases of bird flu in the US “would not be surprising,” given the number of birds that are sick as well as infections in people in other countries who’ve had exposure to avian influenza, the CDC said. And limiting bird flu exposure to humans decreases the ability of the virus to spread person-to-person, which would be a more serious public health threat. 

Here’s what to know about bird flu, or avian influenza. 

What is the bird flu?

The bird flu, aka avian influenza, is the disease caused by infection with influenza type A viruses. These viruses can circulate among birds around the world and have infected humans in rare cases, mostly those who work directly with infected birds. If the viruses mutate enough, the public health fear is that they might make the jump to spread among humans. The bird flu was first detected and controlled in 1997, but it reemerged in 2003 and started spreading widely among birds.

The predominant bird flu virus in the world is H5N1, according to the CDC. Since 2003, more than 880 human cases of earlier strains of H5N1 have been reported in humans. 

Influenza viruses that cause the bird flu are either “low pathogenic” or “highly pathogenic.” Highly pathogenic bird flu can cause severe disease or death in poultry, and it’s those cases that the US Department of Agriculture is reporting. Both low and highly pathogenic viruses have caused mild to severe disease in infected humans. 

The World Health Organization reports four types of influenza viruses: A, B, C and D. Type A viruses, which occur in both humans and different kinds of animals, are the biggest threat to public health and can cause pandemics, the WHO says. The “swine flu” of 2009’s pandemic was caused by a type A virus. Seasonal flu viruses in humans are caused by type A and type B viruses. 

A group of chickens cooped up together.

Getty Images

Is it deadly? 

Though human cases remain rare, about half of previous H5N1 human infections have resulted in death, the CDC said. But, as the agency noted in its April statement on the human case of bird flu, the current H5N1 appears different than earlier strains. The Colorado man who got sick with bird flu this year reported fatigue as his only symptom, and he recovered. 

But because of the potential for a serious health threat, the WHO, CDC and US Department of Agriculture are closely monitoring outbreaks in the US and in other countries. The CDC has said it has “produced a candidate vaccine virus,” if it’s needed, in response to a potential public health threat. 

Signals that bird flu is becoming a bigger public health risk include multiple reports of H5N1 virus infections in people from exposure to birds, or spread between people, the CDC previously said.

Where is it in the US? How is it being monitored?

The bird flu has been detected and reported by the USDA in wild and domestic birds in most US states — 46, as of the CDC’s early November announcement

Henry Niman, a biochemist in Pittsburgh, has been tracking the outbreak (as reported by The New York Times), and his map offers a visual representation of the outbreak across the country.

The first case was in a wild bird in South Carolina. Other cases were reported in some backyard flocks as well as some poultry farms, where animals are raised commercially for food. Any birds of the flocks that have cases of avian flu will not enter the food system, the USDA said.

A poultry worker wearing protective gear holds a chicken.

Karen Moskowitz/Getty Images

Can people catch bird flu? Here are the precautions to take

Birds can shed avian influenza virus in their saliva, feces and mucus, according to the CDC. Humans can get sick by breathing in the virus, or by touching their eyes, nose or mouth. Most human bird flu cases have been reported in people who work directly with birds. 

To avoid getting sick, avoid contact with wild birds, don’t touch dead or sick birds you see, and avoid visiting bird markets or farms if you’re traveling to another country, according to the CDC

Extra precautions or monitoring may be taken if you work directly with birds, if you hunt birds or if you’re a health care worker. If you have contact with an infected bird, contact your local or state health department. Here’s a directory of local health departments in the US.

To avoid contamination from poultry of any kind, make sure to properly handle your poultry and eggs, and thoroughly cook them to 165 degrees Fahrenheit, the USDA says, to kill bacteria and viruses. 

You can also report a dead bird to your local health department or wildlife agency, which will help public health officials track not only the bird flu but also viruses such as West Nile virus. Reporting dead birds might be especially important if you see more than one of them

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.