It’s rare but possible for avian influenza to infect humans. Here’s what you need to know.

April 26, 2022
Leslie Tengelsen, PhD, DVM, state public health veterinarian

Domestic poultry, including chickens and turkeys, infected with highly pathogenic avian influenza (also called bird flu) were first detected earlier this month in Idaho, in Gooding, Caribou, and Madison counties. They were likely infected by migrating geese or ducks.

A type of avian influenza, called highly pathogenic avian influenza A(H5N1), started killing domestic poultry and certain species of wild birds in the United States in mid-January.

It’s extremely rare but still possible for this virus to pass from infected birds to humans. Here are some things to keep in mind now that the virus has been confirmed in Idaho.

What is highly pathogenic avian influenza?

Bird flu is the disease caused by infection with avian influenza viruses. These viruses naturally spread among wild aquatic birds worldwide and can infect domestic poultry and other birds and some animals. Some avian influenza viruses do not cause disease in birds; however, highly pathogenic avian influenza viruses cause severe illness in infected birds. 

Can it make humans sick?

Yes, but only rarely.

Although avian influenza viruses usually do not infect people, there have been some cases of human infection. Human infections with bird flu viruses have occurred most often after unprotected contact with infected birds or surfaces contaminated with the virus. Even so, there have been infections where direct contact with infected birds or their environment could not be verified.

Human infections with bird flu viruses can happen when the virus gets into a person’s eyes, nose, or mouth, or is inhaled. This is possible when virus is in the air (in droplets or possibly dust) and a person breathes it in, or when a person touches something that has virus on it then touches their mouth, eyes, or nose. Infected birds shed virus through their saliva, mucous and feces.

If it’s rare, why is it important to know about it?

It is possible that bird flu viruses could mutate and gain the ability to spread easily between people; therefore, monitoring for human infection and person-to-person spread is extremely important for public health.

What are the symptoms of avian influenza in humans?

Some infected people have had no symptoms. When symptoms were present for others, they ranged from mild illness, such as eye redness or mild flu-like upper respiratory symptoms, to severe illness, including fever, cough, sore throat, runny or stuffy nose, muscle or body aches, headaches, fatigue, and shortness of breath or difficulty breathing. Some people have developed pneumonia requiring hospitalization. Less common signs and symptoms include diarrhea, nausea, vomiting, or seizures.

What are the signs of illness in birds?

Signs of highly pathogenic avian influenza in domestic poultry include decreased appetite and activity, difficulty breathing, dark combs and wattles, and unexplained deaths.

If you have a backyard flock that is experiencing a sudden increase in illness and death, contact the Idaho State Department of Agriculture at 208-332-8540.

If you come across a sick or dead bird in the wild, avoid touching it and report your findings to the Idaho Department of Fish and Game through its website:


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Leslie Tengelsen, PhD, DVM, is the state public health veterinarian in the Division of Public Health. She has worked for the department since 1998 and focuses on zoonotic disease prevention.

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The Idaho Department of Health and Welfare is dedicated to strengthening the health, safety, and independence of Idahoans. Learn more at 

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