Avian influenza, commonly called “bird flu,” is a viral infection that usually spreads in birds but can sometimes spread to humans. Influenza A(H5N1) is the most common cause in humans. It can cause severe respiratory symptoms. People who work with poultry, waterfowl (like geese and ducks) and livestock are most at risk.
Bird flu (avian influenza) is an infection from a type of influenza (flu) virus that usually spreads in birds and other animals. Sometimes, humans can get bird flu from infected animals. Like the versions of flu that people usually get, bird flu can be serious and is much more likely to be deadly. It’s extremely rare for it to spread from person to person.
You might hear about bird flu when there’s an outbreak affecting large numbers of birds or other animals. This is concerning because it increases the risk of human infection, can affect wildlife and can reduce the food supply.
There are many subtypes of avian flu. The most common subtypes that spread to humans are influenza A(H5N1) and influenza A(H7N9). These are named based on types of proteins on the surface of the virus.
So far, bird flu infections in humans are rare. There have been less than 1,000 known cases worldwide since it was first identified in humans in 1997. There have only been two cases in the U.S.
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Symptoms of bird flu include:
A type of influenza A virus, often H5N1 in humans, causes bird flu. The virus can infect your upper respiratory tract and lungs and even spread to other parts of your body, like your brain.
Humans can get bird flu if they come in contact with an infected animal’s body fluid, like spit (saliva), respiratory droplets or poop (feces). You can breathe it in from small dust particles in animal habitats or get it into your eyes, nose or mouth after touching body fluids.
You don’t get bird flu from eating properly cooked poultry or eggs. Any flocks known to have avian flu virus are immediately taken out of the human food supply.
Bird flu is very rarely contagious (spread from person to person), but there have been a few cases of spread between humans. None of these happened in the U.S. In almost all cases so far, human bird flu infections have come from contact with infected animals.
People who work with poultry or waterfowl (like ducks or geese) are at the highest risk for bird flu. You also may be at risk if you work with livestock.
Bird flu can often cause severe illness. Complications include:
Healthcare providers can diagnose avian flu with a throat or nose swab. They don’t routinely test for avian flu, so you have to let them know that you’ve been in contact with birds or other animals that could be infected. They’ll have to send the sample to a special lab to be tested.
If identified early, you can treat bird flu with antiviral medications. A provider might prescribe:
Ways to reduce your risk of bird flu include:
Public health authorities — like the Centers for Disease Control and Prevention (CDC) in the U.S. — monitor cases of bird flu in animals and people to try to reduce the risk of spread. They have vaccines for avian flu that could quickly be put into use if there were a risk of an outbreak.
Some people with bird flu only have mild symptoms, or even no symptoms at all. But many people get severely ill. You may need to stay in the hospital so a healthcare team can monitor your symptoms and treat you for complications right away.
The mortality (death) rate for bird flu in humans is high — over 50% for all known cases worldwide. This means half of all people diagnosed with bird flu die from it.
If you’re at a higher risk for avian influenza, talk to your provider about prevention and when you should seek care if you have symptoms. See a provider if you think you’ve been exposed to bird flu.
Go to the nearest emergency room if you have symptoms of severe illness, including:
It might be helpful to ask your provider:
Bird flu continues to spread in birds around the world. This is a problem for wildlife health, food supply and human health. Cases in people sometimes happen.
It’s not likely, but if a version of bird flu had a gene mutation that allowed it to spread easily between people, it could cause a pandemic.
Cattle and other animals get bird flu in the same way that humans can get it — through breathing in the virus from contaminated dust in animal habitats or direct contact with body fluids of infected animals.
A note from Cleveland Clinic
You might be alarmed when you see headlines about bird flu. But while it’s important to protect yourself if you’re around birds or other animals that carry it, it rarely spreads to humans. Public health officials monitor cases and have a vaccine ready if it becomes a high risk to humans. Talk to a healthcare provider if you have concerns about your risk for bird flu.
Last reviewed by a Cleveland Clinic medical professional on 04/17/2024.
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Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy