**Situation at a glance**
On 27 March 2023, the National Health Commission of the People’s Republic of China notified the World Health Organization (WHO) of a confirmed human infection with an avian influenza A(H3N8) virus. This is the third such case reported, and all three have occurred in China. Epidemiological investigations and close‑contact tracing have been completed, and no additional cases have been identified among the patient’s contacts. Current evidence suggests that the virus does not transmit easily from person to person, so the risk of widespread human transmission at national, regional, or international levels is considered low. Nevertheless, because influenza viruses constantly evolve, WHO emphasizes the need for global surveillance to detect virological, epidemiological, and clinical changes that could affect human or animal health.
**Description of the situation**
The patient was a 56‑year‑old woman from Guangdong province who fell ill on 22 February 2023. She was hospitalized for severe pneumonia on 3 March and died on 16 March. The case was identified through the severe acute respiratory infection (SARI) surveillance system. She had multiple underlying conditions and a history of exposure to live poultry, as well as the presence of wild birds near her home. No close contacts developed infection or symptoms. Environmental samples taken from the patient’s residence and a wet market she visited tested positive for influenza A(H3) in the market samples.
**Epidemiology of the disease**
Zoonotic influenza infections in humans can be asymptomatic or cause disease ranging from mild, flu‑like symptoms to severe acute respiratory illness and death. Rarely, gastrointestinal or neurological symptoms are reported. Human cases of avian influenza usually result from direct or indirect exposure to infected live or dead poultry or contaminated environments.
**Public health response**
China has implemented enhanced monitoring and disinfection around the patient’s residence and suspected exposure sites, and has carried out public risk‑communication activities to improve awareness and promote self‑protection measures.
**WHO risk assessment**
Avian influenza A(H3N8) viruses are widely detected in animals worldwide and are among the most common subtypes in birds, typically causing little or no disease in domestic or wild avian populations. Cross‑species transmission has been documented in mammals such as dogs and horses. This is the third human A(H3N8) infection reported from China; two earlier cases in 2022 presented with critical and mild illness, respectively, and were likely acquired through exposure to infected poultry. No additional cases linked to the current or previous infections have been reported. Preliminary investigations suggest exposure to a live‑poultry market as the probable source, but the exact origin and relationship to circulating animal A(H3N8) viruses remain unclear. More data from human and animal investigations are needed to clarify the public‑health risk. While sporadic human infections are expected as avian influenza continues to circulate in poultry, current epidemiological and virological evidence indicates that A(H3N8) lacks the capacity for sustained human‑to‑human transmission, and the likelihood of such spread is low. Ongoing global surveillance is essential to detect any changes that could affect health.
**WHO advice**
Countries should raise public awareness about avoiding high‑risk environments such as live animal markets, farms, and surfaces contaminated with poultry or bird feces. Good hand hygiene—frequent washing or use of alcohol‑based sanitizer—and respiratory protection in risky settings are recommended. The public should avoid contact with sick or dead wild animals and report such incidents to authorities. Travelers to areas with known animal influenza outbreaks should steer clear of farms, live‑animal markets, slaughter sites, and contaminated surfaces, practice regular hand washing, and follow safe food‑handling practices. WHO does not recommend travel or trade restrictions at this time. Continuous collaboration between animal and human health sectors, systematic epidemiologic and virologic surveillance, and timely information sharing are critical for risk assessment.
**Additional recommendations**
Enhanced surveillance of zoonotic influenza in both animal and human populations is needed, along with comprehensive investigations of each zoonotic event and pandemic planning. Poultry workers should receive seasonal influenza vaccination to reduce the risk of viral mutation that could facilitate human‑to‑human transmission. If a novel influenza infection with pandemic potential is suspected, contact tracing and thorough epidemiological investigations—including travel and animal‑exposure histories—should begin immediately, even before laboratory confirmation. Clinical samples should be tested and forwarded to a WHO Collaborating Centre for detailed characterization. Under the International Health Regulations (2005), states must promptly notify WHO of any laboratory‑confirmed human infection with a new influenza subtype. This event does not alter WHO’s existing recommendations for influenza public‑health measures and surveillance.
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