Avian influenza subtype A(HxNy) normally spreads in birds but can also infect humans. Human infections are primarily acquired through direct contact with infected poultry or contaminated environments. While avian influenza viruses do not currently transmit easily from person to person, the ongoing circulation of these viruses in poultry is concerning, as these viruses can result in mild to severe illness and death, and also have the potential to mutate to become more contagious.

Member States in the WHO’s Western Pacific Region (WPR) communicate and notify the World Health Organization of any human cases of A(HxNy) through the International Health Regulations (IHR 2005) mechanism. WHO’s Western Pacific Regional Office therefore monitors human cases of avian influenza on an ongoing basis and produces a weekly summary report of the situation in the region.

 

Human infection with avian influenza A(H5N1) virus: From 1 January 2003 to 21 December 2023, a total of 248 cases of human infection with avian influenza A(H5N1) virus were reported from four countries within the Western Pacific Region (Table 1). Of these cases, 139 were fatal.

Human infection with avian influenza A(H5N6) virus: As of 31 January 2024, a total of 90 laboratory-confirmed cases of human infection with influenza A(H5N6) virus including 35 deaths were reported to WHO in the Western Pacific Region since 2014. The last case was reported from China on 25 November 2023.

Human infection with avian influenza A(H3N8) virus: As of 31 January 2024, a total of three laboratory-confirmed cases of human infection with influenza A(H3N8) virus with one death were reported to WHO in the Western Pacific Region. The last case was reported from China on 22 February 2023.

 

Human infections with avian influenza A (H7N4) virus in China: As of 31 January 2024, only one laboratory-confirmed case of human infection with influenza A(H7N4) virus was reported to WHO. This case was reported from China on 14 February 2018.

Human infection with avian influenza A(H7N9) virus in China: As of 31 January 2024, a total of 1568 laboratory-confirmed human infections with avian influenza A(H7N9) virus, including 616 fatal cases, were reported to WHO since early 2013. The last case of human infection with avian influenza A(H7N9) reported to WHO in the Western Pacific Region was in 2019.

Human infection with avian influenza A(H9N2): As of 31 January 2024, a total of 94 cases of human infection with avian influenza A(H9N2), including two deaths (both with underlying conditions), were reported to WHO in the Western Pacific Region since December 2015. Of these, 92 were reported from China and two were reported from Cambodia. The last two cases were reported from Sichuan Province, China, with onset dates of 5 November 2023 and 14 November 2023, respectively.

Human infection with avian influenza A(H10N3) in China: As of 31 January 2024 two cases of avian influenza A(H10N3) virus have been reported globally. The last case was reported from Zhejiang, China with an onset date of 11 June 2022.

Other regional surveillance