Based on CDC and WHO guidance, checked against those sources on Oct 12, 2026. Educational information only — not a diagnosis or a substitute for a licensed healthcare professional.
What it is
H5N1 bird flu mainly infects wild birds and poultry and has also spread among some mammals, including U.S. dairy cattle. Human infections are rare and have mostly followed close contact with infected animals. No sustained person-to-person spread has been identified, and CDC rates the risk to the general public as low.
How it spreads
Unprotected contact with sick or dead birds or other infected animals, their droppings, saliva or milk.
Breathing in dust or droplets in contaminated environments (for example barns or poultry houses).
Drinking raw (unpasteurized) milk from infected animals.
No person-to-person spread has been found in the U.S.; a few limited cases have been reported in other countries in the past.
Eye symptoms can start 1–2 days after exposure; breathing symptoms usually start about 3 days after (range about 2–7 days). Watch for symptoms for 10 days after your last exposure.
Excerpt from World Health Organization:On 21 March 2026, the National International Health Regulations (IHR) Focal Point for Italy notified the World Health Organization (WHO) of the identification of a human case of avian influenza A(H9) in an adult male returning from Senegal. Next generation sequencing confirmed Influenza A(H9N2). According to epidemiological investigations, the patient had no known history of exposure to poultry or any person with similar symptoms prior to the onset of symptoms. Authorities in Italy have implemented a series of measures aimed at monitoring, preventing and controlling the situation. According to
Published Apr 10, 2026 · World Health Organization — Disease Outbreak NewsShare card
Excerpt from World Health Organization:On 15 November 2025, WHO was notified of the 71st confirmed human case with influenza A(H5) since early 2024 in the United States of America— the first human case reported in the United States of America since February 2025. On 20 November, U.S. Centers for Disease Control and Prevention (CDC) laboratory sequencing verified the virus as influenza A(H5N5), representing the first globally reported human case caused by an influenza A(H5N5) virus. The investigation by health authorities in the United States of America is ongoing. Contact tracing identified no further cases amongst contacts, and th
Published Dec 5, 2025 · World Health Organization — Disease Outbreak NewsShare card
Excerpt from World Health Organization:Between 1 January and 1 July 2025, the World Health Organization (WHO) was notified by Cambodia’s International Health Regulations (IHR) National Focal Point (NFP) of 11 laboratory-confirmed cases of human infection with avian influenza A(H5N1) virus. Seven of the 11 cases were reported in June, an unusual monthly increase. Avian influenza A(H5N1) was first detected in Cambodia, in December 2003, initially affecting wild birds. Since then, 83 cases of human infection with influenza A(H5N1), including 49 deaths (case fatality ratio [CFR] of 59%), have been reported in the country. While the vir
Published Jul 5, 2025 · World Health Organization — Disease Outbreak NewsShare card
Excerpt from World Health Organization:On 2 April 2025, the International Health Regulations (IHR) National Focal Point (NFP) for Mexico notified the World Health Organization (WHO) of the country’s first laboratory-confirmed human infection with an avian influenza A(H5N1) virus in the state of Durango. In response, local and national health authorities have implemented a range of measures to monitor, prevent, and control the situation. There have been reports of A(H5N1) outbreaks in birds in Durango, although the exact source of infection in this case remains under investigation. To date, no further cases of human infection with i
Published Apr 17, 2025 · World Health Organization — Disease Outbreak NewsShare card
Excerpt from World Health Organization:On 26 August 2024, the International Health Regulations (IHR) National Focal Point (NFP) for Ghana notified the World Health Organization (WHO) regarding the country's first reported human case of infection with a zoonotic (animal) influenza virus. Subsequent laboratory tests confirmed the presence of the avian influenza A(H9N2) virus. According to epidemiological investigations, the patient, under five years old, had no known history of exposure to poultry or any sick person with similar symptoms prior to the onset of symptoms. The Ghanaian government has implemented a series of measures aime
Published Sep 20, 2024 · World Health Organization — Disease Outbreak NewsShare card
Excerpt from World Health Organization:On 20 August 2024, the World Health Organization (WHO) was notified by the country’s International Health Regulations (IHR) National Focal Point (NFP) of a laboratory-confirmed case of human infection with avian influenza A(H5N1) virus (clade 2.3.2.1c) in a 15-year-old child in the Kingdom of Cambodia. This case is one of 10 human cases of influenza A(H5N1) infection reported in Cambodia in 2024. From 2003 to the present, 72 cases of human infection with influenza A(H5N1), including 43 deaths (case fatality ratio [CFR] of 59.7%), have been reported in the country. According to the IHR (2005),
Published Sep 2, 2024 · World Health Organization — Disease Outbreak NewsShare card
Current situation
U.S. wastewater: H5 detected in 3 of 42 states with monitoring (last 28 days)U.S. CDC · Oct 20, 2026
