Bird Flu (Avian Influenza): Symptoms, Causes, and Treatment
Updated: 3 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Quick Answer: What is bird flu?
Bird flu is a flu caused by influenza type A viruses that infect birds and rarely infect humans. People most often catch it through close, long-term contact with live domesticated poultry. Symptoms include fever, breathing problems, pink eye, vomiting and diarrhea, usually within 7 days of exposure. Treatment is antiviral medicine started as early as possible, plus avoiding other people. [1] [2]
What the research says
According to PubMed:
Resistance can emerge during treatment. A review of human A(H5N1) and A(H7N9) cases found oseltamivir-resistance mutations (H274Y and N294S predominating in H5N1), and serious outcomes and mortality were seen in most such cases despite oseltamivir therapy (Abed and Boivin, DOI).
Wild birds carry mostly low-pathogenic strains. A systematic review of 72 publications covering 10,960 migratory birds in Europe and Africa found 86% of avian influenza detections were low-pathogenic and 14% high-pathogenic; H5N1 accounted for 11% of detections (Defaye et al., DOI).
Spillovers are rising. A meta-analysis of 312 studies (2016–2026) estimated that annual high-consequence viral spillover events increased by 4.98% and noted the expansion of H5N1 highly pathogenic avian influenza into dairy cattle (Tao et al., DOI).
Study details are from PubMed abstracts.
At a glance: bird flu
Question | Answer |
What is it? | Avian influenza — a flu caused by influenza type A viruses that infect birds |
How common in humans? | Rare |
How do people catch it? | Close, long-term contact with live poultry; occasionally wild birds or other animals |
How fast do symptoms appear? | Typically within 7 days; can take as long as two weeks |
Can it spread person to person? | Rarely |
How is it treated? | Antiviral medicines (oseltamivir, zanamivir, or peramivir) started early |
What exactly is bird flu?
Bird flu, also called avian influenza, is caused by influenza type A virus infections in bird species. Depending on the strain, it may cause the bird to have no symptoms at all, a mild illness, a serious illness, or death [1].
In humans, flu is a viral infection of the nose, throat, and lungs — the respiratory system. Bird flu symptoms in people are similar to ordinary flu and may range from mild to serious [1].
Bird flu rarely infects humans. But health officials worry because influenza A viruses that infect birds can change (mutate) to infect humans and spread from person to person more often. A new strain would be a completely new virus to humans and could spread quickly around the world [1].
What are the symptoms of bird flu in people?
Symptoms can be mild to serious. They typically show up within seven days of contact with the virus but can take as long as two weeks. A person can get infected from direct contact with an infected animal, or with the animal's bedding or stool [1].
Flu viruses all produce similar symptoms, so you need to be tested to confirm bird flu rather than ordinary seasonal flu [1].
Common bird flu symptoms
Symptom | What it looks like |
Fever | Elevated body temperature, often with chills |
Problems breathing | Shortness of breath, difficulty catching air |
Pink eye | Red, irritated eyes — also called conjunctivitis |
Upset stomach | Nausea and vomiting |
Loose stool | Diarrhea |
Bird flu may cause breathing problems more often than other kinds of flu, and during bird flu outbreaks the risk that a person with flu will need a machine to help them breathe is higher [1].
When to see a doctor
If you have been exposed to bird flu and have any symptoms of illness, see a healthcare professional right away. If your work, travel, or hobbies may have exposed you and you have flu-like symptoms, contact your healthcare professional without waiting [1].
How do you catch bird flu?
Influenza viruses infect the cells that line the nose, throat, and lungs, and spread through breath, saliva, mucus, or stool. You catch bird flu when you inhale virus particles, or when you touch an object with flu particles on it and then touch your eyes, nose, or mouth [1].
People most often catch it from close, long-term contact with live, domesticated poultry, typically on farms or in backyard coops. Rarely, people are exposed through contact with wild birds or another type of animal [1].
Are backyard birds a risk?
Birds you may see in a park or yard, such as crows or sparrows, are not a high risk. They do not usually carry bird flu viruses that infect people or farm animals [1].
Can you catch bird flu from food?
It may be possible to be exposed through undercooked foods such as eggs or poultry. Where bird flu has spread to dairy cows, it may be possible through raw dairy products. Dairy products heated to kill germs (pasteurized) are not a risk for bird flu [1].
What are the risk factors?
The risk of a human catching bird flu is low. Contact with sick poultry or their environment is the most common risk. Rarely, people have caught it after contact with wild birds or other animals, and humans have only rarely passed a bird flu virus to other humans [1].
Risk factor | Level of concern |
Close, long-term contact with sick poultry | Highest — the most common route |
Contact with bedding or stool of infected birds | High — part of poultry exposure |
Wild birds or other animals | Rare |
Person-to-person spread | Rare |
Birds in parks and yards (crows, sparrows) | Low — not usually carriers |
What complications can follow if it isn't treated?
People with bird flu may have worsening medical issues or new health problems, some life-threatening [1]:
Worsening of chronic lung conditions, such as asthma or cystic fibrosis
Ear and sinus infection
Failure of the respiratory system (acute respiratory distress syndrome)
Kidney problems
Heart problems
Bleeding in the lungs, collapsed lung, or bacterial pneumonia
Sepsis
How is bird flu diagnosed?
A healthcare professional takes a sample of fluid from your nose and throat to test for evidence of bird flu infection. They may also sample fluid from your eye if you have pink eye. If you could have been exposed through work, travel, or hobbies and have symptoms, see your healthcare professional right away [2].
How is bird flu treated?
Antivirals stop the flu virus from spreading in the body and work best when started as soon as you have symptoms. For this reason, your healthcare professional may prescribe one before your lab results come back [2].
Antiviral medicines for bird flu
Medicine | Brand name | How it is given |
Oseltamivir | Tamiflu | Taken by mouth |
Zanamivir | Relenza | Inhaled using a device similar to an asthma inhaler |
Peramivir | Rapivab | Given through a needle in a vein |
Preventing the spread
If you have bird flu, stay in an area away from other people, including those you live with if possible, and avoid people while waiting for lab results. Healthcare professionals may suggest testing for people who had close contact with you, and may give antiviral medicine to exposed people at high risk of serious illness [2].
How can you prevent bird flu?
If you work with animals, follow all recommended protective actions. If traveling to a place where bird flu is spreading, avoid poultry farms and bird markets if possible, cook food fully, and wash hands with soap and water after handling food and animals. Get your seasonal flu vaccine every year: it does not prevent bird flu, but it can help you avoid having two flu viruses at the same time. See also CDC prevention guidance.
Everyday protection
Avoid contact with animals who are sick or may be sick. Wild or domestic, keep birds at a distance.
Wear protective gear when needed. Flu viruses enter through the mouth, nose, or eyes, so wear eye protection, a face mask, and gloves where the virus might be present.
Wash your hands with soap and water, especially after touching animals or surfaces dirty with animal mucus, saliva, or stool.
Safe food handling
Getting bird flu from food is very rare, but it is a good idea to follow safe food handling recommendations.
Avoid spreading germs in the kitchen. Use hot, soapy water on all surfaces that touched raw poultry, meat, seafood, or eggs.
Cook food fully. Cook chicken to an internal minimum of 165 F (74 C), eggs until the white and yolk are firm, and egg dishes such as quiche to 160 F (71 C).
Avoid raw dairy products. Raw milk is not pasteurized, so it is more likely to make you sick.
Cooking temperature guide
Food | Safe internal temperature |
Chicken | 165 F (74 C) minimum |
Egg dishes (such as quiche) | 160 F (71 C) |
Whole eggs | White and yolk firm |
Ground beef | 160 F (71 C) |
Whole beef | 145 F (63 C), rest 3 minutes |
Temperature chart source: Foodsafety.gov.
How can everyday hygiene keep bird flu risk low?
Bird flu is a real but rare threat to people. Influenza type A viruses that infect birds can mutate into strains that infect humans and spread quickly, which is why health officials watch them closely. But the path from a farm coop to your living room is long, and everyday steps shorten it further. If your work, travel, or hobbies bring you close to live poultry, take exposure seriously: symptoms usually appear within a week — sometimes two — and look like ordinary flu, so testing is the only way to tell them apart. Treatment works best when started at the first symptom, so act quickly and stay away from others while you wait for results.
Next steps: If you've been exposed to birds that may be sick and have flu-like symptoms, contact a healthcare professional right away and avoid other people while waiting for test results.
Frequently asked questions
Is bird flu common in humans?
No. Bird flu rarely infects humans. The overall risk is low, and it most often affects people with close, long-term contact with live poultry on farms or in backyard coops [1].
Can bird flu symptoms be confused with ordinary flu?
Yes. Fever, breathing problems, pink eye, upset stomach, and diarrhea are all possible bird flu symptoms, but they also match ordinary flu. Symptoms typically show up within seven days of exposure and can take as long as two weeks. You need a test to confirm bird flu [1].
Can bird flu spread from person to person?
Rarely. It most often spreads to humans from infected birds and only occasionally passes between people. Health officials watch it closely because a mutated strain could spread between people more easily [1].
Are park birds like sparrows and crows dangerous?
No. Birds you see in a park or yard are not a high risk. They do not usually carry bird flu viruses that infect people or farm animals [1].
Does pasteurized milk protect against bird flu?
Yes. Dairy products heated to kill germs through pasteurization are not a risk for bird flu. The concern is limited to raw dairy products [1].
This article is for general education and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional about your individual situation.
How soon do bird flu symptoms appear?
Symptoms usually start within 7 days of contact with the virus, but they can take up to 2 weeks to appear.
Is there medicine to treat bird flu?
Yes. Antiviral medicines such as oseltamivir (Tamiflu), zanamivir (Relenza), and peramivir (Rapivab) can treat bird flu. They work best when started as soon as symptoms appear.
Does the seasonal flu shot protect against bird flu?
No. The yearly flu shot does not prevent bird flu, but it can help you avoid having two flu viruses at the same time.
Can you get bird flu from eating chicken or eggs?
Getting bird flu from food is very rare. Cooking chicken to at least 165 F (74 C) and cooking eggs until the white and yolk are firm kills the virus.
How is bird flu diagnosed?
A healthcare professional swabs fluid from your nose and throat, and sometimes your eye if you have pink eye, to test for the virus. A test is needed because bird flu looks like ordinary flu.
Related Reading
Flu Test (Influenza Test): Types, Accuracy and What Results Mean explains how rapid and PCR flu tests work and what results mean.
References
Mayo Clinic Staff. Bird flu (avian influenza) - Symptoms and causes. Mayo Clinic. June 8, 2024. https://www.mayoclinic.org/diseases-conditions/bird-flu/symptoms-causes/syc-20568390
Mayo Clinic Staff. Bird flu (avian influenza) - Diagnosis and treatment. Mayo Clinic. June 8, 2024. https://www.mayoclinic.org/diseases-conditions/bird-flu/diagnosis-treatment/drc-20568430
Abed Y, et al. Oseltamivir Resistance in Human Influenza A(H5N1) and A(H7N9) Infections: A Mini Review. Open Forum Infect Dis. 2026;13(7):ofag393. PMID 42491214. https://doi.org/10.1093/ofid/ofag393
Defaye B, et al. Circulation of avian influenza viruses in migratory birds in Europe and in Africa: a systematic review. Emerg Microbes Infect. 2026;15(1):2728774. PMID 42751944. https://doi.org/10.1080/22221751.2026.2728774
Tao P, et al. Systematic Review and Meta-Analysis of Emerging Viral Zoonotic Diseases, 2016-2026. Transbound Emerg Dis. 2026;2026(1):e9884191. PMID 42811656. https://doi.org/10.1155/tbed/9884191
Centers for Disease Control and Prevention. Bird Flu: Causes and How It Spreads. Centers for Disease Control and Prevention. April 23, 2025. https://www.cdc.gov/bird-flu/virus-transmission/index.html
Centers for Disease Control and Prevention. Preventing Bird Flu Infections. Centers for Disease Control and Prevention. April 23, 2025. https://www.cdc.gov/bird-flu/prevention/index.html
FoodSafety.gov. Cook to a Safe Minimum Internal Temperature. FoodSafety.gov. Reviewed November 21, 2024. https://www.foodsafety.gov/food-safety-charts/safe-minimum-internal-temperatures
Centers for Disease Control and Prevention. About Bird Flu. Centers for Disease Control and Prevention. December 30, 2024. https://www.cdc.gov/bird-flu/about/index.html
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