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Hong Kong CHP investigating An H9 avian flu human case - February 21, 2024

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  • Hong Kong CHP investigating An H9 avian flu human case - February 21, 2024

    Hong Kong CHP Investigating An H9 Infection


    When we talk about avian influenza viruses with pandemic potential, H5 and H7 subtypes rank highest on our list, as several (H5N1, H5N6, H7N9, etc.) have a track record of causing severe and often fatal illness in humans (see Cambodia MOH Reports 5th H5N1 Case of 2024).

    Luckily, none have acquired the ability to transmit easily from human-to-human, and therefore have only caused sporadic, albeit sometimes sizable, outbreaks in humans.

    These aren't the only avian flu threats, however, and one of the other subtypes we spend a good deal of our time watching is LPAI (Low Pathogenic Avian Influenza) H9N2 which is common in poultry in Asia, the Middle East, and parts of Africa.

    Unlike the more virulent H5 and H7 avian viruses, H9N2 in poultry is not considered a `reportable' disease by the OIE/WOAH, and so our understanding of its range and continued spread is limited.

    The CDC has designated 2 different lineages (A(H9N2) G1 and A(H9N2) Y280) for their short list of influenza viruses with zoonotic potential (see CDC IRAT SCORE), and several candidate vaccines have been developed.

    A little over a month ago, in Frontiers in Public Health: Human Infections of H9N2 Avian Influenza Virus in China (in 2021) we looked at some of the recent evolutionary changes seen in this virus.

    Although only about 100 (mostly mild) human infections have been documented (see FluTrackers list) over the past 2 decades, seroprevalence studies suggest this is likely a significant undercount.

    Today Hong Kong's CHP reports their 9th case on record, and the first since 2020.

    CHP investigating case of influenza A (H9) infection

    The Centre for Health Protection (CHP) of the Department of Health (DH) is today (February 21) investigating a case of influenza A (H9) infection affecting a 22-month-old girl.

    The patient has developed fever and cough with sputum since February 15 and was brought to Union Hospital for medical advice on February 16. No hospitalisation was required at that time. Her clinical specimen was tested positive for the influenza A (H9) virus today upon testing by the Public Health Laboratory Services Branch of the CHP. Subtyping result is pending. Her clinical diagnosis was avian influenza. She is in stable condition and arrangements have been made for her to be admitted to isolation ward of Princess Margaret Hospital for further treatment.

    Preliminary investigation of the CHP revealed that the patient had visited Zhongshan during the incubation period. The patient had no direct poultry contact recently, nor consumption of undercooked poultry, or contact with patients. One of her home contacts developed sore throat on February 17 who had taken medication and the symptom had subsided. Her other home contacts are asymptomatic so far. Investigations are ongoing.

    The CHP will inform the health authority of Guangdong and the World Health Organization of the case.

    Novel influenza A infection, including influenza A (H9), is a notifiable infectious disease in Hong Kong. Influenza A (H9N2) infection is a mild form of avia seroprevalence studiesn influenza. Nine cases of influenza A (H9N2) had been reported since 1999. The recent case was an imported case reported in 2020. No deaths have been recorded so far.

    A spokesman for the CHP explained that a stringent surveillance mechanism with public and private hospitals, with practising doctors and at boundary control points is firmly in place. Suspected cases will be immediately referred to public hospitals for follow-up investigation.

    "Travellers, especially those returning from avian influenza-affected areas and provinces with fever or respiratory symptoms, should immediately wear masks, seek medical attention and reveal their travel history to doctors. Healthcare professionals should pay special attention to patients who might have had contact with poultry, birds or their droppings in affected areas and provinces," the spokesman advised.

    Members of the public should remain vigilant and take heed of the preventive advice against avian influenza below:
    • Do not visit live poultry markets. Avoid contact with poultry, birds and their droppings. If contact has been made, thoroughly wash hands with soap;
    • Poultry and eggs should be thoroughly cooked before eating;
    • Wash hands frequently with soap, especially before touching the mouth, nose or eyes, handling food or eating; after going to the toilet or touching public installations or equipment (including escalator handrails, elevator control panels and door knobs); or when hands are dirtied by respiratory secretions after coughing or sneezing;
    • Cover the nose and mouth while sneezing or coughing, hold the spit with a tissue and put it into a covered dustbin;
    • Avoid crowded places and contact with fever patients;
    • Wear masks when respiratory symptoms develop or when taking care of fever patients;
    • Travellers if feeling unwell when outside Hong Kong, especially if having a fever or cough, should wear a surgical mask and inform the hotel staff or tour leader and seek medical advice at once; and
    • Travellers returning from affected areas with avian influenza outbreaks should consult doctors promptly if they have flu-like symptoms, and inform the doctor of the travel history and wear a surgical mask to help prevent spread of the disease.
    The public may visit the CHP's avian influenza page ( and website ( for more information on avian influenza-affected areas and provinces.

    Ends/Wednesday, February 21, 2024
    Issued at HKT 21:00

    All medical discussions are for educational purposes. I am not a doctor, just a retired paramedic. Nothing I post should be construed as specific medical advice. If you have a medical problem, see your physician.