Avian influenza—often called bird flu—is not one disease caused only by H5N1. It is a group of influenza A viruses that can infect poultry, wild birds and, less commonly, mammals and people. Some infections cause few obvious signs. Highly pathogenic avian influenza (HPAI) can spread rapidly and kill poultry without warning.
Suspect bird flu? Treat it as an emergency.
Stop moving birds, eggs, manure, equipment and visitors. Keep people and pets away. Contact a veterinarian and your local animal-health authority immediately. Do not slaughter, sell, give away or privately medicate suspected birds.
What avian influenza means
For flock owners, the main distinction is between low pathogenicity avian influenza (LPAI) and high pathogenicity avian influenza (HPAI). These terms describe effects in poultry; they do not predict severity in a person.
- LPAI: may cause no visible illness or mild respiratory signs and reduced egg production. Certain H5 and H7 LPAI viruses can change into highly pathogenic forms after circulating in poultry.
- HPAI: can cause severe systemic disease, sudden death and rapid flock losses. HPAI viruses reported in birds have historically belonged to H5 or H7 subtypes.
H5N1 is an important HPAI subtype, but it is not the only avian influenza virus. Laboratory testing—not symptoms, dropping colour or photographs—is required for diagnosis.
Verified facts at a glance
Mortality in a standard chicken test is one alternative criterion in the formal HPAI definition. It is a laboratory threshold, not a forecast for every outbreak.
Naturally occurring HPAI viruses identified in birds have belonged to H5 or H7 subtypes, although most H5 and H7 viruses are not highly pathogenic.
CDC assessed the general public-health risk from the current A(H5) situation as low in March 2026. Risk is higher with unprotected animal exposure.
Sources: WOAH Code and CDC situation summary. Assessments can change; check the linked update.
How bird flu spreads
Infected birds shed virus in respiratory secretions and faeces. Infection can move directly between birds or indirectly on contaminated boots, hands, clothing, crates, tools, vehicles, water and litter. Wild waterfowl and shorebirds can carry avian influenza viruses, sometimes without appearing sick.
Signs in poultry
Signs vary with the virus, bird species, age and immune status. Warning signs include:
- sudden or unexplained deaths;
- a rapid increase in mortality;
- loss of appetite, energy or water consumption;
- a sudden fall in egg production or soft, misshapen eggs;
- swelling around the eyes, head, comb, wattles or shanks;
- purple or blue discolouration of the comb, wattles or legs;
- coughing, sneezing, nasal discharge or difficulty breathing;
- tremors, twisted neck, stumbling or inability to stand;
- watery diarrhoea.
These signs also occur with Newcastle disease, severe bacterial infections, poisoning and other conditions. Unlike our guides to Gumboro disease, aspergillosis and abnormal chicken droppings, suspected avian influenza requires urgent official reporting.
What to do when you suspect avian influenza
Outbreak response: five immediate actions
Stop all bird, egg, manure and equipment movement.
Keep visitors, children, pets and unnecessary workers away.
Close the affected area without chasing or handling birds unnecessarily.
Call a veterinarian and the competent animal-health authority.
Follow official sampling, PPE, cleaning and disposal instructions.
Do not carry a carcass to a market, feed store, laboratory or clinic without instructions. Record sick and dead bird numbers, when signs began, recent purchases, visitors and movements. Give this information to the responding veterinarian.
Reporting differs by country. Contact your government veterinary service, agriculture ministry or local animal-health authority. United States keepers can use USDA APHIS guidance.
Can avian influenza be treated?
There is no approved flock-level medicine that cures HPAI in poultry. Antibiotics do not kill influenza viruses. Supportive care, herbs, garlic, vinegar, vitamins and improvised remedies cannot make a suspect flock safe and may delay reporting.
Official control can include quarantine, testing, humane depopulation, safe disposal, cleaning, disinfection, surveillance and movement restrictions. The responsible authority sets the response.
Vaccination is not a home treatment
Some countries use vaccination within official control programmes. Vaccine choice, coverage, surveillance and monitoring must match circulating viruses and national policy. Vaccination cannot cure infected birds, replace biosecurity or justify moving a suspect flock. It can affect surveillance and trade, so owners should never vaccinate outside veterinary and regulatory guidance.
How to reduce the risk
- Prevent poultry from contacting wild birds and their droppings.
- Keep feed and bedding covered; provide treated or protected water.
- Use dedicated footwear and clothing inside poultry areas.
- Clean visible dirt before applying disinfectant at its correct concentration and contact time.
- Restrict visitors and record necessary farm entries.
- Do not share crates, tools or vehicles unless properly cleaned and disinfected.
- Quarantine new or returning birds under veterinary guidance.
- Control rodents and insects; exclude pets from poultry houses.
- Inspect birds daily and record mortality, feed, water and egg production.
Human safety around sick or dead birds
Human infection remains uncommon, but unprotected contact with infected animals or contaminated environments raises risk. Do not touch sick or dead birds, faeces, litter or contaminated surfaces with bare hands. Keep children and unnecessary people away.
Use only the personal protective equipment specified by health or animal authorities. Wash hands thoroughly after leaving the area. Do not eat, drink or touch your face while handling animals.
After exposure, seek public-health advice promptly if you develop eye redness, fever, cough, sore throat, breathing difficulty, runny nose, body aches, headache, fatigue, diarrhoea or vomiting. Tell the clinician about the bird exposure before arrival. CDC notes that conjunctivitis has been prominent among recent United States cases.
Official video: monitoring H5N1
Video source: U.S. Centers for Disease Control and Prevention. No autoplay.
Frequently asked questions
Can people catch bird flu from poultry?
Yes, but infection is uncommon. Risk is concentrated among people with unprotected exposure to infected birds, animals or contaminated environments.
Is sudden death enough to diagnose bird flu?
No. It is an emergency warning sign, not a diagnosis. A veterinarian and authorised laboratory must investigate.
Can I eat eggs or meat from a suspect flock?
Do not slaughter, sell, distribute or consume products from a suspected or restricted flock. Follow food-safety and animal-health instructions. Cooking does not cancel disease-control restrictions or make handling a suspect bird safe.
Should I move healthy-looking birds away?
No. Apparently healthy birds may still be infected. Moving them can spread disease. Stop movement and wait for official instructions.
Sources and editorial note
- WOAH: Avian influenza
- WOAH Terrestrial Animal Health Code, Chapter 10.4
- USDA APHIS: signs and response
- USDA Defend the Flock
- CDC: current situation
- CDC: signs and symptoms in people
Reviewed against official guidance in August 2026. Outbreak status, reporting rules and public-health assessments can change. Follow your national authorities’ current guidance.
