ETIDIOH - NEW

  ABSTRACT H5N1 high pathogenicity avian influenza virus (HPAIV) has spread in wild birds and poultry worldwide . H5N1 HPAIV belonging to the currently predominant clade 2.3.4.4b has infected not only birds but also mammals (wild and domestic animals), with several human infections also being reported, raising concerns for public health . In 2022, a clade 2.3.4.4b H5N1 HPAIV strain, A/Ezo red fox/Hokkaido/1/2022 (H5N1; Fox/Hok/1/22), was isolated from an Ezo red fox (Vulpes vulpes schrencki) in Hokkaido , Japan; this was the first reported case of clade 2.3.4.4b H5N1 HPAIV isolation from a mammalian species in Japan. Several amino acid substitutions in the PB2 protein play an important role in the adaptation of avian influenza viruses to mammals, but Fox/Hok/1/22 PB2 does not have any of these well-known mammalian-adapting PB2 substitutions. Here, we investigated the biological properties of Fox/Hok/1/22 in a mouse model and found that this virus was highly virulent in mice and rep...

  Abstract Highly pathogenic avian influenza A virus (HPAIV) H5N1, clade 2.3.4.4b, has emerged as a significant zoonotic threat . H5N1 is widely circulating in wild birds , and an increasing number of spillover events have been observed in a wide range of mammalian species . These cases are primarily reported in countries on the European and American continents . This review describes the likely transmission routes, lesions, and clinical manifestations of HPAIV H5N1 clade 2.3.4.4b in naturally infected mammals, with a focus on the involvement of the central nervous system (CNS). In the analysis, pathological findings were categorized by organ system and host species , which were further divided into terrestrial mammals, marine mammals, and dairy cattle . The most frequently reported clinical manifestations were neurological and respiratory signs in marine mammals and neurological signs and lethargy in terrestrial mammals . Macroscopic and histological lesions were commonly found in...

  Abstract Influenza A virus (IAV) can infect a wide range of hosts, including wild and domestic pigs . Swine play an important role in influenza evolution and epidemiology due to their ability to get infected with both avian and human influenza viruses, potentially leading to reassorted virus variants . Interactions at the wild-domestic swine interface have been documented on multiple occasions, raising concern about pathogen transmission and the emergence of novel influenza strains. This study investigates the occurrence and subtypes of IAV infecting invasive wild pigs in Alberta, Canada . A total of 267 wild pigs were captured between 2021–2024. Exposure to IAV was initially detected by cELISA , with further confirmation of exposure to the H5Nx virus by hemagglutination inhibition (HI) and virus neutralization (VN) assays. Although no IAV genetic material was detected by qPCR , the seropositive samples by cELISA (4.17%; 5/120) coincided with the 2022–2024 highly pathogenic avian...

Unspecified wild species sample from Jeollabuk-do Region. Source:  Link:  https://wahis.woah.org/#/in-review/6967 ____

  Abstract Background   Infection of backyard and poultry with low pathogenicity avian influenza LPAI A(H5N2) viruses has occurred in Mexico since 1994, and the first human infection caused by this influenza virus was detected in 2024 . Since its emergence in the Americas , frequent reassortments between high pathogenicity avian influenza HPAI A(H5N1) and LPAI viruses has occurred. In September 2025 , the Instituto Nacional de Enfermedades Respiratorias of Mexico City identified an unsubtypeable influenza A virus infection in a young adult patient later determined to be a reassortant HPAI (H5N2) virus with a clade 2.3.4.4b HA .  Methods   We analyzed clinical and epidemiologic data from this patient. Respiratory samples were tested for influenza RT-qPCR assays . Genomic sequence and phylogenetics analyses were performed to provisionally assign a new genotype to the novel HPAI A(H5N2) reassortant virus.  Results   The patient presented with fever and tachypn...

  {Summary} Confirmed Cases at National Level [National - Total Cases : 71 { +1 }{§}] [Cases -  Exposure Source] -- 41 - Dairy Herds (Cattle){*} -- 24 - Poultry Farms and Culling Operations {*} -- 3 - Other Animal Exposure {†} -- 3 - Exposure Source Unknown {‡} Probable Cases at National Level [National - Total Cases : 7 {no change} ] [Cases -  Exposure Source] -- 1 - Dairy Herds (Cattle) {*} -- 5 - Poultry Farms and Culling Operations {*} --  0 - Other Animal Exposure {†} -- 1 - Exposure Source Unknown {‡} NOTE : One additional case was previously detected in a poultry worker in Colorado in 2022. Louisiana reported the first H5 bird flu death in the U.S. {*} Exposure Associated with Commercial Agriculture and Related Operations {†} Exposure was related to other animals such as backyard flocks, wild birds, or other mammals {‡} Exposure source was not able to be identified (...) {§} A case from Washington State, see more at:  https://doh.wa.gov/newsroom/grays-h...

  Abstract Three critically ill or fatal avian influenza A(H5N1) human infections have been reported in North America since November 2024 . Notably, all were infected with genotype D1.1 instead of B3.13, the dominant genotype before November 2024. Here, we demonstrated that D1.1 could replicate to higher titers in human nasal and airway organoid-derived transwell monolayers from 6 donors . D1.1 exhibited a better binding to α2,3- and α2,6-linked SA than B3.13. No significant differences in most inflammatory or antiviral cytokines/chemokines was observed. These observations suggest that D1.1 is better adapted to both the upper and lower human respiratory tract epithelium than B3.13. Source:  Link:  https://academic.oup.com/jid/advance-article/doi/10.1093/infdis/jiaf598/8341570#google_vignette ____

  Abstract The evolutionary divergence of the A(H5) hemagglutinin (HA) gene of high pathogenicity avian influenza (HPAI) viruses (A/goose/Guangdong/96 lineage) was analyzed by phylogenetic and average pairwise distance methods to identify clades that merit nomenclature updates . Based on this assessment, 12 new clade designations were recommended based on division of clade 2.3.2.1c and 2.3.4.4 viruses, which were reported in Africa, Antarctica, Asia, Europe, the Middle East, the Americas and Oceania since the most recent WHO/WOAH/FAO H5 Evolution Working Group update. Competing Interest Statement The authors have declared no competing interest. Source:  Link:  https://www.biorxiv.org/content/10.1101/2025.11.23.690055v1 ____

  A poultry farm in Opolskie Region. Source:  Link:  https://wahis.woah.org/#/in-review/7037 ____

  {Summary} Time Period: November 09, 2025 - November 15, 2025 -- H5 Detection :  1 site(s) ( 0.3% ) -- No Detection :  382 site(s) ( 99.7% ) -- No samples in last week :  75 site(s) (...) Source:  Link:  https://www.cdc.gov/nwss/rv/wwd-h5.html ____

Wild Species (unspecified) in Xinjiang Uygur Region. Source:  Link:  https://wahis.woah.org/#/in-review/6978 ____

  A poultry farm in Oberösterreich Region. Source:  Link:  https://wahis.woah.org/#/in-review/7024 ____

  • New human cases {1,2}:  -- From 30 September to 5 November 2025 , based on reporting date, the detection of influenza A(H5N1) in one human , A( H5N2 ) in one human and A( H9N2 ) in two humans were reported officially.   • Circulation of influenza viruses with zoonotic potential in animals :  -- High pathogenicity avian influenza (HPAI) events in poultry and non-poultry animal species 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 in the above human infection events.  -- Based on information available at the time of this risk assessment update , the overall public health risk from currently known influenza A viruses detected at the human-animal interface has not changed...

A slaughter turkeys operation in Kujawsko-Pomorskie Region. Source: WOAH,  https://wahis.woah.org/#/in-review/7012 ____

  {Hessen Region} laying hens (500), broilers (200), ducks for fattening (200), geese for fattening (700), turkeys for fattening (500) Source: WOAH,  https://wahis.woah.org/#/in-review/7021 ____

  Phnom Penh, November 16 (Xinhua) -- Cambodia's Ministry of Health confirmed on the 16th that a young man residing in Phnom Penh had died from avian influenza (H5N1). Authorities urged the public to be vigilant and take effective preventative measures. According to the report, the 22-year-old man experienced severe symptoms including fever, cough, shortness of breath, and difficulty breathing . Despite the medical team's best efforts, his condition rapidly deteriorated, and he died on the 15th of this month . This is the first reported human death from avian influenza in the country's capital this year. Following the incident, the Cambodian Ministry of Health immediately activated its emergency response mechanism . Local professional teams are conducting a comprehensive and detailed epidemiological investigation to trace the source of infection and identify close contacts . To prevent further spread of the epidemic in the community, authorities have urgently allocated and ...

  A 22-year-old Cambodian man died of H5N1 bird flu , the Ministry of Health said in a statement released Sunday, November 16, 2025, as reported by Xinhua and quoted by Antara. "Laboratory results from the Cambodian National Institute of Public Health on November 15, 2025 , showed that the man was positive for H5N1 virus infection," the Cambodian Ministry of Health said in a statement. (...) Source: Tempo,  https://www.tempo.co/internasional/pria-kamboja-tewas-akibat-flu-burung-h5n1-2090146 ____

  {Excerpt} National situation summary Person-to-person spread :  None -- There is no known person-to-person spread at this time. Current public health risk :  Low -- The current public health risk is Low. Cases in the U.S. :  71 cases Deaths in U.S. :  1 death (...) Situation summary of confirmed and probable human cases since 2024 {Confirmed Cases}:  -- National: Total Cases: 71 {+1} [Cases - Exposure Source] -- 41 - Dairy Herds (Cattle){*} -- 24 - Poultry Farms and Culling Operations{*} -- 3 - Other Animal Exposure{†} -- 3 - Exposure Source Unknown{‡} {Probable Cases}:  -- National: Total Cases: 7 [Cases - Exposure Source] -- 1 - Dairy Herds (Cattle){*} -- 5 - Poultry Farms and Culling Operations{*} -- 0 - Other Animal Exposure{†} -- 1 - Exposure Source Unknown{‡} NOTE : One additional case was previously detected in a poultry worker in Colorado in 2022. Louisiana reported the first H5 bird flu death in the U.S. {*} Exposure Associated with Comm...

  {Scotland} Broiler breeder flock of 28-week-old birds. Increased mortality and other clinical signs reported. Samples taken were found positive for HPAI H5N1. Source: WOAH,  https://wahis.woah.org/#/in-review/7013 ____

Human Avian Influenza Cases in Washington State Residents {*} [Exposure - Probable - Confirmed - Total human cases (H5)] -- Poultry - 3 - 11 - 14 -- Unknown - 1{^} - 0 - 1 -- Total - 15 {*} Washington residency could not be confirmed for one case with exposure to poultry in Washington. {^} Currently under investigation; case classification and source of infection may be updated. Note : Updates to national public health reporting and notification of novel influenza A infections were approved by the Council of State and Territorial Epidemiologists (CSTE) in June 2024 and enacted in September 2024. Whether a case is counted as confirmed or probable is determined after completion of a public health case investigation and takes into account a person's exposure to avian influenza virus, whether confirmatory testing at the CDC was negative or positive, and whether a person experienced symptoms of illness. The specific criteria used to determine if a case is confirmed, or probable is based...