ETIDIOH - NEW

  The Official Veterinary Service (OVS) of the state of Mato Grosso received a notification of a suspected case influenza A viruses of high pathogenicity in domestic birds from a multi-species backyard , on December 20, 2025. Official Laboratory (LFDA-SP) analysis confirmed the presence of the H5N1 virus, clade 2.3.4.4b. The premises have been placed under quarantine. Birds will be culled, and carcasses, products, and any potentially contaminated materials will be destroyed. The OVS is currently conducting an epidemiological investigation in the surrounding area. Source:  Link:  https://wahis.woah.org/#/in-review/7147 ____

  Abstract Since 2021, highly pathogenic avian influenza viruses (HPAIV) belonging to H5N1 clade 2.3.4.4b have caused high mortality in North American wild birds and poultry . In 2025 , a new D1.1 genotype caused two human deaths and host-switched to dairy cattle . However, the evolutionary origins and dynamics of D1.1 have not been fully characterized. Here, our phylogenetic analysis of 17,516 H5N1 genome sequences uncovers how D1.1 introduced a major shift in the antigenic diversity and ecology of the H5N1 epizootic in North America. D1.1 is the first major H5N1 genotype to (a) emerge in the Pacific flyway and spread west-to-east faster than any prior genotype; (b) antigenically shift via reassortment with the North American N1 segment, displacing the previously fixed Eurasian N1 ; and (c) transmit to a broader range of host species than any H5N1 genotype to date, introducing mammalian adaptations . Competing Interest Statement The authors have declared no competing interest. Fun...

  Abstract Poultry workers in Washington, USA, were infected with highly pathogenic avian influenza A(H5N1) virus and recovered. The viruses were clade 2.3.4.4b genotype D1.1, closely related to viruses causing poultry outbreaks . Continued surveillance and testing for influenza A(H5) clade 2.3.4.4b viruses remain essential for risk assessment and pandemic preparedness of zoonotic influenza viruses. Source:  Link:  https://wwwnc.cdc.gov/eid/article/31/12/25-1118_article ____

  Abstract Many pathogens, both those with human spillover potential as well as avian-specific viruses, are maintained in wild bird populations . While much surveillance for influenza A viruses (IAVs) is performed annually, surveillance for other pathogens is limited. Sampling of wild birds is often time-consuming , labour-intensive, involves physically handling wild birds, often limited in sample size, and involves handling of potentially infected birds , posing an increased risk of direct exposure for personnel. Given this, additional methods for surveillance are needed. Longitudinal, bi-weekly fecal and sediment sampling was performed at various sites in southern Manitoba, Canada , particularly focused in Winnipeg from May - October 2025. Sites were chosen based on the suitability of the area for waterfowl habitat , the presence of waterfowl in the area, as well as sites in proximity to reported outbreaks of H5N1 influenza virus . Fecal and sediment samples were collected and sc...

  Influenza at the human-animal interface  Summary and risk assessment, from 6 November to 19 December 2025 {1} -- New human cases {1,2}:  - From 6 November to 19 December 2025, based on reporting date , the detection of influenza A( H5N1 ) in one human , A( H5N5 ) in one human , A( H9N2 ) in seven humans , and an influenza A( H1N1 ) variant virus in one human were reported officially.  - In addition , one human case of infection with an influenza A( H1N2 ) variant virus was detected.  -- 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}  - Additionally, low pathogenicity avian influenza viruses as well a...

  ~155K laying chickens’ flock. Samples taken were positive for HPAI H5N1. Birds presented clinical signs prior to testing. Source:  Link:  https://wahis.woah.org/#/in-review/7139 ____

  Abstract Highly pathogenic avian influenza H5N1 poses an increasing public health risk, particularly following its spillover into dairy cows and associated human infections in the U.S. since March 2024. Here, we systematically identified critical PB2 mutations emerged during avian-to-cattle transmission and subsequent adaptation in cattle , notably PB2 M631L, which conferred pathogenicity in mice comparable to the well-characterized PB2 E627K mutation . Retrospective analysis reveals that PB2 631L also circulated in avian and human H5N1 strains during the 2013–2014 outbreaks in Cambodia and Vietnam . Additional adaptive mutations include established markers ( E627K, Q591R, D701N ), and novel variants ( I647V, G685R, K736R ). These mutations enhance polymerase activity by improving the utilization of both bovine and human ANP32A proteins , thereby increasing viral fitness and pathogenicity in mammals . The convergence of these adaptations highlights the elevated zoonotic risk of c...

  Abstract Avian influenza virus (AIV) infections in cats are a new and not fully understood  problem  in Poland . These infections have drawn the attention of both veterinarians  and human medical  practitioners , mainly because of their zoonotic  potential , i.e. possible spreading to humans and  other mammals . In wild felids as  well as in domestic cats , AIV can cause severe infections , often  ending in death.  Highly pathogenic avian influenza virus (HPAIV) and low pathogenic avian  influenza virus (LPAIV) have been identified, with the recent H5N1 (2.3.4.4b  clade) outbreak  affecting poultry, wild birds and carnivores .  Transmission likely occurs through contact with  infected birds , their excretions or  contaminated raw poultry , while cat-to-cat transmission  remains unconfirmed .  First reported in Thailand in 2003, H5N1 infections in cats have since  occurred in  multiple c...

  WASHINGTON, D.C., December 19, 2025 On December 14, 2025, USDA’s Animal and Plant Health Inspection Service (APHIS) announced the first detection of highly pathogenic avian influenza (HPAI) in a dairy herd in Wisconsin .  On December 17 , the National Veterinary Services Laboratories (NVSL) completed whole genome sequencing and confirmed that the virus is H5N1 clade 2.3.4.4b genotype D1.1.  Analysis indicates that this detection is a new spillover event from wildlife into dairy cattle, separate from previous events. Key Points -- Most detections in U.S. dairy herds have resulted from movements linked to the original spillover event that occurred in the Texas Panhandle in late 2023, involving the B3.13 strain . -- In early 2025, through the National Milk Testing Strategy , USDA detected two spillover events in Nevada and Arizona dairy herds. Both were identified early, and no further herd infections occurred through animal movements. These events involved the D1.1 strain...

  Abstract Highly Pathogenic Avian Influenza (HPAI) viruses, particularly IAV (H5N1), continue to pose a major global threat due to their widespread circulation and high mortality rates in birds. Management of HPAI is complicated by challenges in conserving migratory bird populations, sustaining poultry production, and uncertainties in disease dynamics. Structured decision-making frameworks , such as those based on the PrOACT model, are recommended to improve outbreak response and guide critical actions , especially when HPAI virus (HPAIV) detections occur in sensitive areas like wildlife refuges . Surveillance data from late 2024 to early 2025 show persistent HPAI activity , with 743 detections across 22 European countries and beyond, and notable outbreaks in poultry in nations like Hungary, Iceland, and the UK . The proximity of poultry farms to water sources increases environmental contamination risks. Meanwhile, HPAI A(IAV (H5N1)) and other H5Nx viruses have been detected in a ...

  {Excerpt} Time Period: December 07, 2025 - December 13, 2025 {*} -- H5 Detection :   3 site(s) ( 0.7% ) -- No Detection :  451 site(s) ( 99.3% ) -- No samples in last week :  37 site(s) {*} Note: The H5 detection at site 2030 in Virginia is a result of a data error and is a false detection. This will be corrected in the next update. (...) Source:  Link:  https://www.cdc.gov/nwss/rv/wwd-h5.html ____

{Höör Region} A farm with parent poultry. All animals were euthanized 18 December. A protection zone (3 km) and a surveillance zone (10 km) have been put in place around the infected farm and all other restrictions and necessary measures according to Regulation (EU) 2016/429 and EU DR 2020/687 are applied. Source:  Link:  https://wahis.woah.org/#/in-review/7136 ____

  A poultry farm in Łódzkie Region. Source:  Link:  https://wahis.woah.org/#/in-review/7137 ____

  {Excerpt} Since 1997, more than 1000 cases of highly pathogenic avian influenza A(H5N1) have been reported in humans . During this time, A(H5N1) viruses have evolved into dozens of clades , showing ever-expanding phylogenetic diversification and geographical spread . Over the past 5 years, clade 2.3.4.4b A(H5N1) viruses have exhibited rapid global expansion in migratory birds, with spillover to an increasing range of marine and terrestrial mammalian species . Among these species are dairy cattle , not previously recognised as a permissive host for influenza A viruses (IAV), leading to widespread clade 2.3.4.4b A(H5N1) outbreaks in herds in the USA and sporadic human infections linked with exposure to infected animals since March 2024. While person-to-person transmission has not been detected in the USA, the increased geographical distribution of and susceptibility of mammalian hosts to clade 2.3.4.4b A(H5N1) viruses has brought to the forefront a need to assess the pandemic risk ...

  Summary Background Highly pathogenic avian influenza H5N1 viruses of the A/Goose/Guangdong/1/1996 lineage pose a global threat to wildlife, domestic animals, and humans . Cross-species transmission events to mammals, including humans , in the past 4 years highlight this threat. For influenza A viruses, crucial determinants of cross-species and intraspecies transmission to and among mammals include attachment to and replication in respiratory airway epithelial cells . Although these determinants have been studied for H5N1 viruses in the past, limited studies for clade 2.3.4.4b viruses exist. Therefore, the aim of this study was to determine the ability of recent clade 2.3.4.4b H5N1 viruses to attach to human respiratory tissues, to replicate in human airway epithelial cells and the associated immune response. Methods In this in-vitro study, we investigated three H5N1 clade 2.3.4.4b viruses (H5N1Gull2022, H5N1Polecat2022, and H5N1Bovine2024) in comparison with previously studied 2....

  By Andrey Gulivanov - Taiga bean goose, CC BY 2.0,  https://commons.wikimedia.org/w/index.php?curid=161227833 __ A wild Bean Goose in Łódzkie Region. Source:  Link:  https://wahis.woah.org/#/in-review/7127 ____

  Abstract Zoonotic spillover of influenza A viruses into humans has repeatedly triggered pandemics throughout history. Since their emergence in the 1990s, H5N1 influenza viruses have significantly expanded their geographical range and host species , raising global concern about the potential for sustained human-to-human transmission . In this review , we examine the virological characteristics of currently circulating H5N1 strains, key molecular barriers limiting their spread among humans, and critical areas of future research to mitigate the ongoing H5N1 panzootic and prevent future pandemics. Source:  Link:  https://academic.oup.com/immunohorizons/article/9/SI/vlaf062/8381786 ____

  Abstract In the austral summer 2023/2024, H5N1 high pathogenicity avian influenza virus (HPAIV) was reported for the first time in Antarctica . Concerns of HPAIV causing high mortality of seabirds and mammals prompted immediate efforts to track its spread and impact on endemic wildlife. In March 2024, we visited the Danger Islands archipelago , that hosts two mega-colonies of Adélie penguins , and observed an unusual mortality estimated in thousands of Adélie penguins and other species . Swabs and tissues were collected for molecular detection of infectious agents from 49 carcasses, and additional tissues for histology from a selection of 9 carcasses. We unexpectedly detected Pasteurella multocida DNA in 46 of 49 individuals, and diagnosed avian cholera , and not HPAI , as the cause of death of most of these animals. By metagenomics, we retrieved the genomic sequences of the Pasteurella multocida strain which caused the epizootic, and the phylogenetic analysis showed a close rela...