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{Excerpt} Avian influenza A(H9N2) :  -- Guangxi Zhuang Autonomous Region :  - A five-year-old boy with onset on March 3, 2025.  -- Guizhou Province :  - A 35-year-old woman with onset on March 10, 2025.  -- Henan Province - A seven-year-old girl with onset on February 11, 2025.  (...) Source: Centre for Health Protection, Hong Kong PRC SAR,  https://www.chp.gov.hk/files/pdf/2025_avian_influenza_report_vol21_wk15.pdf ____

Abstract Background :  As a natural accelerator of highly pathogenic avian influenza in wild birds , the H9 subtype of avian influenza poses a substantial threat to both humans and the poultry industry . A comprehensive meta-analysis is necessary to assess the current status of the global H9 outbreak. In this research, a literature review and meta-analysis are presented on the surveillance studies of the H9 subtype of avian influenza in wild birds worldwide up to 2024. Methods :  A comprehensive search strategy was employed, utilizing the China Science and Technology Journal Database, China National Knowledge Infrastructure, PubMed, Google Scholar, and Scientific Direct databases. The exclusion criteria for this study included duplicate studies, reviews, other host studies, as well as research with inconsistent or insufficient data. An analysis was conducted on data obtained from a total of 31 publications. The rate-conversion analyses were conducted using a random-effects mod...

Abstract H9N2 avian influenza virus (AIV) is endemic in poultry worldwide and increasingly zoonotic . Despite the long-term widespread use of inactivated vaccines , H9N2 AIVs remain dominant in chicken flocks. We demonstrated that inactivated vaccines did not prevent the replication of H9N2 AIVs in the upper airway of vaccinated chickens. Viral transmission was enhanced during sequential passage in vaccinated chickens, which was attributed to the restricted production of defective interfering particles and the introduction of stable mutations (NP-N417D, M1-V219I, and NS1-R140W) which enhanced viral replication. Notably, the genetic diversity of H9N2 AIVs was greater and included more potential mammal/human-adapted mutations after passage through vaccinated chickens than through naïve chickens, which might facilitate the emergence of mammal-adapted strains. By contrast, vaccines inducing cellular/mucosal immunity in the upper respiratory tract effectively limit H9N2 AIV. These findings ...

Influenza at the human-animal interface Summary and risk assessment, from 21 January to 19 March 2025 {1}  New human cases {2}:  From 21 January to 19 March 2025, based on reporting date , the detection of influenza A( H5N1 ) in five humans, influenza A( H9N2 ) virus in four humans, influenza A( H1N1 ) variant ((H1N1)v) virus in one human, and influenza A( H1N2 )v virus in one human were reported officially.  • Circulation of influenza viruses with zoonotic potential in animals:  -- High pathogenicity avian influenza (HPAI) events in poultry and non-poultry continue to be reported to the World Organisation for Animal Health (WOAH).{3}  The Food and Agriculture Organization of the United Nations (FAO) also provides a global update on avian influenza viruses with pandemic potential.{4}  • Risk assessment {5}:  -- Sustained human to human transmission has not been reported from these events. Based on information available at the time of the risk assessmen...

February 2025  The development of influenza candidate vaccine viruses (CVVs),  coordinated by WHO, remains an essential component of the overall global  strategy for influenza pandemic preparedness . Selection and development of  CVVs are the first steps towards timely vaccine production and do not imply a  recommendation for initiating manufacture. National authorities may consider the  use of 1 or more of these CVVs for pilot lot vaccine production, clinical trials and  other pandemic preparedness purposes based on their assessment of public health  risk and need. Zoonotic influenza viruses continue to be identified  and evolve both antigenically and genetically, leading to the need for additional  CVVs for pandemic preparedness purposes. Changes in the antigenic and genetic  characteristics of these viruses relative to existing CVVs and their potential risks  to public health justify the need to develop new CVVs. This docume...

Context and significance Wang et al. provided valuable insights into the epidemiological patterns of avian influenza virus (AIV) spillover and the role of H9N2 in the process. Their analysis highlighted the significant contribution of the internal genes (INGEs) from 12 key strains of H9N2 in facilitating human adaptability by reducing the species barrier between poultry and humans , essentially acting as internal genetic donors for AIV spillover . Due to its low pathogenicity, H9N2 has been neglected in poultry vaccination programs , leading to a lack of vaccines specifically targeting the INGEs of these 12 key strains. Their findings suggest that reducing the prevalence of H9N2 is fundamental to mitigating AIV spillover risks. Highlights •  H9N2 exerts a promoting effect on the spillover of avian influenza viruses (AIVs) •  Expansion of AIV spatial and host ranges reveals an emerging risk of its spillover •  Prevalence of AIVs in human -contacted hosts reveals a re-emerg...

Significance The dominance of the H9N2 subtype of avian influenza virus (AIV) within the influenza A virus family has raised questions regarding the factors influencing its epidemiological dominance . This study concentrates on the role of five major evolutionary patterns of the matrix protein M1 in the replication and transmission of H9N2 AIVs. The findings indicate a strong correlation between the epidemiological dominance of H9N2 AIVs and the specific M1 patterns , particularly M1P5. It highlights the significance of genetic patterns in M1 for understanding the adaptive differences and turnover of epidemiological dominant H9N2 AIVs. Abstract The H9N2 subtype of avian influenza virus (AIV) emerges as a significant member of the influenza A virus family. However, the varying degrees of epidemiological dominance among different lineages or clades of H9N2 AIVs have not been fully clarified. The matrix protein M1 , a key structural component of the virion , plays a crucial role in mainta...

Abstract In April 2024, Vietnam confirmed its first human case of influenza A(H9N2) in a 37-year-old man , marking a critical point in regional infectious disease monitoring and response. This case underscores the importance of robust surveillance systems and One Health collaboration in managing emerging zoonotic threats. Source: Emerging Infectious Diseases Journal,  https://wwwnc.cdc.gov/eid/article/31/2/24-1146_article ____

 {Excerpt} {Avian Influenza H9N2 Human Cases in China} -- Mainland China:  2 cases (0 death)  - Avian influenza A(H9N2):  * Guangdong Province :  - A 72-year-old woman with onset on December 26, 2024.  - A 56-year-old woman with onset on January 20, 2025.  (...) Source: Centre for Health Protection, Hong Kong PRC SAR,  https://www.chp.gov.hk/files/pdf/2025_avian_influenza_report_vol21_wk07.pdf ____

Abstract The H9N2 subtype of avian influenza virus poses significant challenges to global poultry and human health . During the active surveillance of avian influenza virus in wild birds in Shanghai from 2020 to 2023, a total of nine H9N2 viruses were identified. To better understand the genetic characteristics of these H9N2 viruses in Shanghai, the whole genome sequences were analyzed. Phylogenetical analysis showed that the nine H9N2 viruses have undergone complicated reassortment with waterfowl viruses along the East Asian-Australasian flyways . The nine H9N2 viruses were classified into seven genotypes , and some of them could contribute internal genes to recently circulating HPAI A( H5N8 ) and A( H5N1 ) viruses of clade 2.3.4.4b. These results highlight the importance of active surveillance of AIVs in wild birds to comprehend viral ecology and evaluate potential transmission risk in poultry and humans. Source: Poultry Sciences,  https://www.sciencedirect.com/science/article/pi...

 {Excerpt} Avian Influenza Report - VOLUME 21, NUMBER 6 - Reporting period: Feb 2, 2025 – Feb 8, 2025 (Week 6), (Published on February 11, 2025)  -- Mainland China: 2 new cases (0 death cases):  - Avian influenza A(H9N2) :  - Hunan Province :  - 1) A two-year-old boy with onset on December 27, 2024.   - 2) A 15-year-old boy with onset on January 8, 2025.  (...) Source: Centre for Health Protection, Hong Kong PRC SAR,  https://www.chp.gov.hk/files/pdf/2025_avian_influenza_report_vol21_wk06.pdf _____

ABSTRACT Reassortant highly pathogenic avian influenza A(H5N2) clade 2.3.4.4.b viruses were detected from ducks and environmental samples in Egypt , June 2024. Genomic and phylogenetic analyses revealed a novel genotype produced by the reassortment of an A( H5N1 ) clade 2.3.3.4b virus with an A( H9N2 ) G1-like virus. Monitoring the spread of this virus is important. Source: Emerging Microbes and Infections,  https://www.tandfonline.com/doi/full/10.1080/22221751.2025.2455601#abstract _____

New human cases {2}:  From 13 December 2024 to 20 January 2025, the detection of influenza A(H5) virus in five humans , influenza A( H9N2 ) virus in two humans , and influenza A( H10N3 ) virus in one human were reported officially. Additionally, five human cases of infection with influenza A(H5) viruses were detected.   Circulation of influenza viruses with zoonotic potential in animals :  High pathogenicity avian influenza (HPAI) events in poultry and non-poultry continue to be reported to the World Organisation for Animal Health (WOAH).{3} The Food and Agriculture Organization of the United Nations (FAO) also provides a global update on avian influenza viruses with pandemic potential.{4}   Risk assessment {5}:  Based on information available at the time of the risk assessment , the overall public health risk from currently known influenza viruses at the human-animal interface has not changed remains low . Sustained human to human transmission has not...