#Portugal - #Influenza A #H5N1 viruses of high pathogenicity (Inf. with) (non-poultry including wild birds) (2017-) - Immediate notification

 

After several months without detection of HPAI circulation, these are the first outbreaks confirmed in 2026.

{Lisboa Region} Yellow-legged gull with weakness and neurological clinical signs found at a city park.

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By Andreas Trepte - Own work, CC BY-SA 2.5, https://commons.wikimedia.org/w/index.php?curid=723467

{Aveiro Region} Lesser black-backed gull with neurological clinical signs found at a fishing port.

Source: 

Link: https://wahis.woah.org/#/in-review/7671

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#Australia notifies first case of High Pathogenicity Avian #Influenza #H5N1 in a wild #bird (WOAH, June 30 '26)

    On 20 June 2026, WOAH was notified of the first detection of high pathogenicity avian influenza (HPAI) H5N1 in Australia in a marine wild bird, a migratory brown skua (Stercorarius antarcticus). 

    The virus is related to H5N1 HPAI clade 2.3.4.4b viruses, which is the same subtype that is predominantly circulating in poultry, wild birds, and mammals globally. 

    Enhanced general and targeted surveillance is underway by the animal health authorities to determine the extent of infection. 

    An epidemiological investigation has commenced.

    HPAI H5N1 has caused a global panzootic since 2021, affecting wild birds, poultry, and multiple mammalian species. 

    Until recently, Australia remained free of this particular subtype despite widespread international incursions.

    Since its emergence, this H5N1 subtype has crossed continents, reaching North and South America in 2022 and extending to the Antarctic islands in 2023. 

    It has since been detected in new host species such as cattle, and marine mammals, caused sporadic human infections, driven exceptionally high activity in wild birds in 2025, and is now being reported in Australia for the first time.

    The World Organisation for Animal Health (WOAH) acknowledges Australia’s immediate notification of Influenza A virus of high pathogenicity in non-poultry birds through the World Animal Health Information System (WAHIS)   and commends Australia for its longstanding commitment to transparency and to the protection of global animal health.

    This notification represents a significant epidemiological event, documenting the first detection of HPAI H5N1 in a wild bird in Australia. 

    The finding confirms the incursion of this globally circulating virus lineage into wildlife in a subregion that had remained free from this subtype despite its extensive international spread in other regions and sub-regions. 

    The risk for Australian avifauna, especially endemic bird species is significant.

    This detection underscores critical considerations: 

        ° Early detection remains our strongest line of prevention 

        ° Early detection and timely reporting linked to early response measures, are essential in limiting the spread of HPAI and reducing its impact on poultry, livestock, wildlife, livelihoods and human health. This event demonstrates the value of sustained surveillance systems, laboratory capacity and field awareness in identifying emerging threats.

    ° Transparency and solidarity strengthen global preparedness 

    ° Timely reporting through WAHIS   allows countries to access official information, assess risks and coordinate responses based on reliable scientific evidence.  

    ° Preparedness requires sustained investment 

        Preparedness is best built before an emergency. Recent events demonstrate the cost of waiting. According to WOAH’s State of the World’s Animal Health 2026 report, more than 2,000 outbreaks of HPAI were reported by 64 countries and territories between 2025 and 2026, resulting in the loss or culling of more than 140 million poultry. At the same time, animal health continues to receive only a small fraction – 0.6% – of global health investment. Strong Veterinary Services, well-equipped laboratories, collaboration with WOAH Reference Laboratories, effective surveillance systems, trained personnel, One Health collaboration, international networks of expertise such as OFFLU and emergency preparedness plans do not emerge during a crisis – they are built through sustained investment over time.

    ° Continued national and international investment remains essential to reduce the impact of HPAI and other emerging animal health threats. 

    ° Multisectoral collaboration 

        This event also highlights the importance of maintaining strong scientific collaboration networks and engaging stakeholders before emergencies arise. Governments, Veterinary Services, laboratories, researchers, wildlife authorities, public health authorities, industry and international organisations play complementary roles in strengthening preparedness and response.  

        WOAH remains committed to supporting its Members through international standards, scientific expertise, capacity building and transparent information sharing. As HPAI continues to evolve globally, continued collaboration, preparedness and collective action remain essential to protect animal health, safeguard livelihoods and strengthen global health security. 

    ° WOAH calls on its Members to:  

        - Maintain enhanced avian influenza SURVEILLANCE  in domestic and wild birds and consider HPAI in differential diagnosis for other susceptible wild or domestic animal species.   

        - REPORT cases of HPAI in all animal species, including in domestic and wild mammals, to WOAH through its World Animal Health Information System (WAHIS)    . Genetic sequences of avian influenza viruses should be shared in publicly available databases. 

        - COLLABORATE with public health authorities, wildlife authorities and other relevant partners through a One Health approach to strengthen surveillance, risk assessment, preparedness and response.

        - CONSIDER  poultry vaccination    as a possible complementary avian influenza control measure;

        - PREVENT the introduction and spread of the disease by implementing strict biosecurity measures in poultry holdings and 

        - EMPLOY good   production and hygiene practices     when handling animal products. Relevant measures notably include keeping poultry away from contact with wild birds, ensuring good hygiene in poultry housing and equipment and reporting bird illnesses and deaths to the Veterinary Services. 

        - PROTECT humans and other potentially susceptible mammals (both wild and domestic). People in close contact or exposed to wildlife should always take   precautionary measures     to avoid getting infected and minimise the risk of mechanically carrying the virus.   

        - AVOID IMPLEMENTING unjustified trade restrictions. Import risk management measures should be scientifically justified and in line with the WOAH International Standards. 

    ° WOAH is fully committed to supporting its Members to mitigate the risks associated with avian influenza. We will continue to engage with our networks of experts, OFFLU, as well as public and private partners, notably through the One Health Quadripartite   and the Global Framework for Transboundary Animal Diseases (GF-TADs)     to provide technical updates as more information becomes available. 

    ° In collaboration with its  Reference Centres  , networks of experts and Members including the WOAH WildNet network of collaborating centres on wildlife health, the WOAH remains in close contact with Australian Veterinary Authorities to monitor the situation to assess the risks to poultry,  wildlife, other susceptible animal species and humans. Australia’s rapid detection and transparent reporting demonstrate the value of strong surveillance systems and international cooperation. As HPAI continues to evolve and spread across regions and species, timely information sharing, scientific collaboration and sustained preparedness remain essential to protect animal and public health. Transparent reporting is also critical to maintaining trust, supporting evidence-based decision-making and preventing misinformation and disinformation. 

Source: 

Link: https://www.woah.org/en/australia-notifies-first-case-of-high-pathogenicity-avian-influenza-h5n1-in-a-wild-bird/

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#Sialic acid-anchored #haemagglutinin stalk neutralizing #antibody M-SiaB enhances #protection against highly pathogenic #influenza #H5N1/Texas/2024

 

Abstract

The recently emerged cattle H5N1/Texas/2024 strain highlights the need for effective prophylactic and therapeutic drug interventions, yet most existing neutralizing antibodies (NAbs) have limited efficacy against genetically divergent pathogenic influenza viruses. Here we engineer a sialic acid-anchored tandem M-SiaB by fusing a hemagglutinin (HA) stalk-specific monoclonal NAb with a sialic acid-receptor-binding domain (SiaB). M-SiaB shows 4- to 20-fold greater neutralizing potency against diverse authentic influenza viruses compared to the parental NAb and suppresses multiple stages of the viral life cycle, including viral attachment, entry and release. Importantly, intranasal M-SiaB confers markedly enhanced protection against nasal challenges with the pathogenic H1N1/PR8 and H5N1/Texas/2024 strains. Notably, a single dose of M‑SiaB maintains survival after a highly lethal H5N1/Texas/2024 challenge for up to 21 days. These findings demonstrate that simultaneously targeting HA stalk and sialic acid-receptor is a promising strategy to enhance the potency and breadth of NAbs against genetically divergent pathogenic influenza viruses.

Source: Nature Communications, https://www.nature.com/ncomms/

Link: https://www.nature.com/articles/s41467-026-74633-5

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Detection of #H5N1-Related #PB1 Sequences in a Low Pathogenic #H11N2 Virus from South #American Migratory #Shorebirds

 

Abstract

Highly pathogenic avian influenza (HPAI) A(H5N1) viruses of clade 2.3.4.4b have recently spread across the Americas, prompting intensified surveillance efforts in Brazil aimed at early detection in wild birds. As part of these efforts, we identified a low pathogenic avian influenza A(H11N2) virus in a white-rumped sandpiper (Calidris fuscicollis) sampled at Lagoa do Peixe National Park (PNLP) in southern Brazil. Whole-genome sequencing revealed that seven of the eight gene segments shared high nucleotide similarity (approximately 98.8%) with viruses previously detected in shorebirds from Delaware Bay, North America. In contrast, the PB1 segment showed high nucleotide similarity (approximately 99%) to the PB1 lineage associated with clade 2.3.4.4b A(H5N1) genotype B3.2 viruses circulating in the Americas. Phylogenetic, nucleotide identity, and molecular clock analyses indicated that this lineage shares a recent common ancestor with North American LPAI viruses and was subsequently detected in distinct viral genetic backgrounds. Although no HPAI virus was identified in this study, the presence of a PB1 segment related to H5N1-associated lineages suggests that genetic components linked to these viruses were circulating among low pathogenic avian influenza viruses in South America. These findings highlight the importance of continued surveillance in migratory bird populations to improve understanding of avian influenza virus diversity and support epidemiological monitoring.

Source: 

Link: https://www.mdpi.com/1999-4915/18/7/710

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Avian #influenza #overview March–May 2026 (ECDC, Summary, June 26 '26)

26 June 2026

Publication series: Avian influenza overview

    

    Between 28 February and 4 June 2026, 949 highly pathogenic avian influenza (HPAI) A(H5) virus detections were reported in domestic (186) and wild (763) birds in 30 countries in Europe.

Abstract

    The downward trend in the number of detections observed at the end of the previous reporting period continued and is expected to persist throughout the summer. 

    While the number of HPAI A(H5N1) outbreaks in domestic birds remained at a low level, except in a few countries, A(H9N2) virus of clade G5.5 was detected in poultry in Europe for the first time. 

    Following the intense circulation of HPAI viruses in waterfowl in recent months, sporadic detections were reported in mammals, particularly in wild carnivores, including the detection of A(H5N5) virus in a polar bear and a walrus in Norway. 

    Outside Europe, the focus of HPAI virus detections shifted from North to South America, where a large number of outbreaks and mortality events in swans were reported. 

    Between 28 February and 4 June 2026, 19 cases of avian influenza virus infection were publicly reported in humans (including three fatal cases) in six countries and territories: Bangladesh (two cases with A(H5N1), one fatal), Cambodia (three cases with A(H5N1), one fatal), India (one case with A(H5N1)), Italy (one imported case with A(H9N2)), China (10 A(H9N2) cases and one fatal A(H5N6) case), and Taiwan (one A(H7N7) case). 

    Most human cases reported exposure to poultry or a poultry environment prior to detection or onset of illness. 

    Human infections with avian influenza viruses remain rare and no sustained human-to-human transmission has been documented. 

    The risk posed by avian influenza A(H5N1) clade 2.3.4.4b viruses currently circulating in Europe remains low for the general public in the European Union/European Economic Area (EU/EEA) and low-to-moderate for those occupationally or otherwise exposed to infected animals or contaminated environments.

Source: 

Link: https://www.ecdc.europa.eu/en/publications-data/avian-influenza-overview-march-may-2026

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Detection of #antibodies against avian #influenza in #European dairy #cattle, the #Netherlands, January 2026

 

Abstract

In December 2025, highly pathogenic avian influenza (HPAI) H5N1 clade 2.3.4.4b genotype DI.2.1 virus was detected in a cat living on a dairy cattle farm. Milk and serum samples from the dairy cattle were tested for avian influenza virus. No viral RNA was detected; however, H5N1-specific antibodies were identified in serum samples from 34 (47.2%) of 72 lactating dairy cows and 24 (63.2%) of 38 youngstock. These demonstrate expansion of the mammalian host range of HPAI H5N1 in Europe.

Source: 

Link: https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2026.31.25.2600464#abstract_content

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A #bovine #H5N1 virus efficiently replicates in differentiated #human #nasal epithelial #cells

 

Abstract

Highly pathogenic avian influenza (H5N1) viruses of clade 2.3.4.4b have caused significant losses in bird populations worldwide and repeatedly infected mammals, including humans, without sustained human to human transmission. Here we show that an H5N1 virus (H5N1Tex/24) isolated from bovine milk in Texas in 2024 replicates just as efficiently in differentiated human nasal epithelial cells as a pandemic H1N1 virus strain from 2009 (H1N1HH4/09), at both 37 °C and 33 °C. The adaptive mutations PB2 M631L and PA K497R promoted replication at 33 °C but had no effect on replication at 37 °C. An H5N1 virus (H5N1BE/22) isolated from a pelican in 2022, which lacked these mutations, replicated efficiently at 37 °C but poorly at 33 °C, and this limitation was not overcome by the introduction of the PB2 M631L and PA K497R mutations. The differentiated nasal epithelial cell cultures expressed receptors for both human and avian influenza viruses. Accordingly, no HA mutations associated with altered receptor specificity were detected. H5N1Tex/24 was able to effectively suppress the production of interferon-λ, yet remained sensitive to the antiviral effects of this cytokine. These findings suggest that H5N1Tex/24 possesses intrinsic traits supporting efficient replication in differentiated human upper airway cell cultures.

Source: npj Viruses, https://www.nature.com/npjviruses/

Link: https://www.nature.com/articles/s44298-026-00208-2

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Identification of HLA-A33-restricted #CD8+ T cell epitopes from avian #influenza #H5N1

 

Abstract

The rapid evolution of avian influenza A/H5N1, including the recent U.S. clade 2.3.4.4b outbreak, highlights its pandemic potential and the urgent need for durable, broadly protective vaccines. Given the capacity of CD8+ T cells to mediate cross-strain immunity, we investigated whether geographically distinct HLA-A33 allotypes, HLA-A*33:01 in East/Southeast Asia and HLA-A*33:03 in South Asia, differentially shape the influenza immunopeptidome and influence antiviral immunity. Antigen-presenting cells overexpressing HLA-A*33:01 or HLA-A*33:03 were transfected with single A/H5N1 antigens or infected with A/X-31 (H3N2) as a control comparison representing current seasonal influenza virus. We identified novel ligands restricted to HLA-A*33:01 (57 from A/H5N1; 55 from A/X-31) and HLA-A*33:03 (29 from A/H5N1; 45 from A/X-31). Although fewer peptides were recovered for HLA-A*33:03, a larger proportion of A/X-31-derived peptides were predicted as high-affinity binders (74%) compared with HLA-A*33:01 (61%), indicating qualitative differences in antigen presentation. To determine immunogenicity, peripheral blood lymphocytes from HLA-A*33:03-positive, A/H5N1-naïve donors were stimulated with four conserved peptides: PB2GTF, PB2KTY, NPSVQ and PB1MTK. All elicited robust CD8+ T cell activation despite the absence of prior A/H5N1 exposure, demonstrating cross-recognition by memory T cells primed against seasonal influenza. These findings define HLA-A33-restricted influenza epitopes and reveal allotype-specific presentation features that shape CD8+ T cell immunity. Conserved, immunogenic peptides identified here represent promising candidates for rational design of broadly cross-reactive vaccines to protect HLA-A33-expressing populations against severe A/H5N1 disease. Data are available via ProteomeXchange with identifier PXD078870.

Competing Interest Statement

AWP is a scientific advisor for Bioinformatics Solutions Inc (Canada), a shareholder and scientific advisor for Evaxion Biotech (Denmark), and a co-founder of Resseptor Therapeutics (Australia). These organisations had no role in the design of the study in the collection, analyses, or interpretation of data in the writing of the manuscript or in the decision to publish the results. All other authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Funder Information Declared

NHMRC, 1122099, 2016596

Source: BioRxIV, https://www.biorxiv.org/

Link: https://www.biorxiv.org/content/10.64898/2026.06.21.733083v1

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#Australia - #Influenza A #H5N1 viruses of high pathogenicity (Inf. with) (non-poultry including wild birds) (2017-) - Immediate notification

 

{Click on Image to Enlarge}

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By Liam Quinn from Canada - Brown Skua landing near a penguin colony. Uploaded by Snowmanradio, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=15465669

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    This is the first detection of H5N1 HPAI clade 2.3.4.4b in a wild bird, in a single migratory brown skua (Stercorarius antarcticus). 

    This is the first detection of H5 HPAI in a wild bird Australia. 

    The virus is related to H5N1 HPAI clade 2.3.4.4b viruses detected in southern Indian Ocean territories. 

    The bird was displaying clinical signs of leg paralysis, weakness and dehydration at Cape Le Grand national park near Esperance, Western Australia. 

    Brown skuas are vagrant species that occasionally visit Australia. 

    There is no poultry production in the region. 

    Enhanced general and targeted surveillance is underway to determine the extent of infection. 

    An epidemiological investigation has commenced. 

    A public information strategy is being implemented. 

    All coordinates provided are approximate.

Source: 

Link: https://wahis.woah.org/#/in-review/7649

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Lower limit of #detection of commercial respiratory virus RT – #PCR panels for #bovine #influenza #H5N1

 

Abstract

Objectives

The adaptation of clade 2.3.4.4b influenza A(H5N1) to dozens of mammalian species, including dairy cattle, raises concerns about potential spillover into humans. If the virus develops human-to-human transmissibility, sensitive diagnostics will be critical to containment efforts. We sought to determine the lower limit of detection of commercial influenza A tests for the circulating bovine-adapted strain of H5N1.

Methods

We determined the 95% lower limit of detection (LLOD) of 4 commercial respiratory virus panels for detecting inactivated bovine H5N1 (A/bovine/Ohio/B24OSU-439/2024). Two of the tested panels provide seasonal influenza A subtyping, the BioFire Respiratory Panel 2.1 (BioFire Diagnostics/BioMérieux) and the cobas eplex respiratory pathogen panel 2 (Roche Diagnostics), while 2 panels provide pan–influenza A detection, the Xpert Xpress CoV-2/Flu/RSV plus (Cepheid), and the Panther Fusion SARS-CoV-2/Flu A/B/RSV Assay (Hologic, Inc). Serial dilutions of H5 RNA (400-25 copies/mL) were prepared in respiratory virus–negative nasopharyngeal swab matrix, and 20 replicates were tested at each concentration. The 95% LLOD for each test was calculated using probit regression.

Results

All 4 tests detected H5 with 95% LLODs below 1000 H5 RNA copies/mL. Xpert demonstrated the highest analytical sensitivity (50 copies/mL; 95% CI, 39-160), followed by BioFire (297 copies/mL; 95% CI, 196-3955), Panther Fusion (531 copies/mL; 95% CI, 421-792), and eplex (883 copies/mL; 95% CI, 588-2741).

Conclusions

Existing commercial respiratory virus panels can effectively detect bovine H5N1. These platforms could support screening in the event of an H5N1 outbreak, followed by confirmation with specific H5 subtyping, as needed.

Source: 

Link: https://academic.oup.com/ajcp/article-abstract/165/6/aqag067/8709618?redirectedFrom=fulltext

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Mass #mortality of southern elephant #seals during multi-species #outbreak of HPAI #H5N1 on sub - #Antarctic Heard Island

 

Abstract

High pathogenicity avian influenza (HPAI) has spread across the sub-Antarctic, causing significant wildlife impacts. We report its first detection in an Australian external territory, Heard Island and McDonald Islands, which supports over one million breeding seabirds and seals. Drone and ground surveys (October 2025, January 2026), combined with viral genome analysis, confirmed infection with Influenza A H5N1 clade 2.3.4.4b at Heard Island. Drone surveys revealed mass mortality in southern elephant seals, with 8,573 pups (62%) recorded dead across Heard Island by the final surveys. Mortality increased at an average rate of 5.6% per day in a subset of harems, and the highest observed mortality in a harem was 97%. Based on the average (76%) mortality in the final surveys, total estimated pup mortality at Heard Island was 13,359 (from a total population of 17,364 pups), though this may be an underestimate as mortality was ongoing at this time. HPAI was detected in six of nine species tested and, we suspect, led to elevated mortality in king and gentoo penguins. Phylogenetic analysis indicates the virus was introduced from Crozet Islands, with an estimated arrival around August 2025. These data show the continued easterly spread of HPAI around the sub-Antarctic, with severe but heterogeneous impacts across taxa. Our results demonstrate the value of drones for large scale monitoring, underscoring the need for continued and enhanced HPAI surveillance across the Southern Ocean.

Competing Interest Statement

The authors have declared no competing interest.

Source: 

Link: https://www.biorxiv.org/content/10.64898/2026.06.16.732752v1

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The Winners Take It All? #Global Evolutionary #Success of #H5Nx #Reassortants in the 2020–2024 #Panzootic

 

Abstract

Avian influenza viruses undergo frequent genetic reassortment, which can coincide with phenotypic changes in transmission, pathogenicity, and host species niche. Since 2020, clade 2.3.4.4b H5 high pathogenicity avian influenza viruses (HPAIVs) have driven a global panzootic, causing mass mortality in wild birds, poultry, and, for the first time, repeated spillover infections in a variety of mammalian species. This worldwide resurgence of H5 HPAIV has coincided with a dramatic increase in the number of circulating reassortant strains; however, the scale, impact and drivers of these reassortants remain unclear. Here, we combined statistical and phylodynamic modelling to reconstruct the global evolutionary dynamics of H5Nx viruses across four epizootic seasons (2020-2024). We identified 209 genetically distinct reassortants, stratified into three transmission categories based on their phylogenetic and epidemiological profiles. Accounting for sampling depth and HPAIV incidence, we estimated that reassortants emerged most frequently from Asia, but `major' reassortants associated with increased host range, inter-seasonal persistence, and long-range dissemination, more frequently emerged from Europe. Altogether, reassortant emergence followed an episodic pattern in which most reassortants were transient, but 2% seeded large clusters of secondary reassortants soon after their own emergence. Statistical modelling revealed that reassortant success was strongly shaped by ecological factors, including sustained circulation in specific wild bird orders and detection across a wider range of host niches. Collectively, our findings uncover global reassortment dynamics in H5 HPAIVs and identify key virological and ecological drivers underpinning the emergence and spread of successful reassortants. These insights support the importance of enhanced surveillance to track evolution of H5 HPAIV and identify traits relevant for consideration in pandemic risk assessment.

Competing Interest Statement

The authors have declared no competing interest.

Funder Information Declared

Biotechnology and Biological Sciences Research Council, BB/V011286/1, BB/X006204/1, BB/X006166/1, BB/Y007271/1, BB/Y007298/1

Biotechnology and Biological Sciences Research Council - Institute Strategic Grants, BBS/E/RL/230002C, BBS/E/RL/230002D

Medical Research Council, MR/Y015045/1, MR/Y03368X/1

National Natural Science Foundation of China, https://ror.org/01h0zpd94, 32061123001, 32425053, 32200416

National Key Research and Development Program of China, 2023YFC2307500, 2024YFE0106000

European Union, 727922, 874850, 101094685, 101084171, 874735

Fonds National de la Recherche Scientifique, F.4515.22

Fonds voor Wetenschappelijk Onderzoek — Vlaanderen, G098321N

Source: 

Link: https://www.biorxiv.org/content/10.1101/2025.07.19.665680v2

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#Bhutan - High pathogenicity avian #influenza #H5N1 viruses (Inf. with) (#poultry) - Immediate notification

 

A poultry farm in Samdrupjongkhar Region.

Source: 

Link: https://wahis.woah.org/#/in-review/7623

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#Sweden - High pathogenicity avian #influenza #H5N1 viruses (Inf. with) (#poultry) - Immediate notification

{Helsingborg Region} This is a farm with mallards for restocking for game and breeding for this purpose. The mallards showed an increse in mortality. Euthanasia is ongoing. 

Source: 

Link: https://wahis.woah.org/#/in-review/7622

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#Genomic #wastewater #surveillance of seasonal and #zoonotic #influenza A viruses in #California during the 2024-2025 flu season

 

Abstract

Wastewater genomic surveillance provides an opportunity to detect human and animal influenza A virus (IAV). We aimed to implement an IAV genomic surveillance framework agnostic to subtype, which enables recovery of IAV from multiple hosts and estimation of proportions across subtypes. We conducted IAV genomic surveillance in wastewater during the 2024-2025 flu season at multiple sites in California and compared these data with available human clinical IAV sequences and test positivity. We applied a custom whole-genome, multi-host IAV probe enrichment panel and adapted our custom expectation-maximization (EM) algorithm to deconvolute IAV mixtures in wastewater and infer subtype relative abundances. Absolute IAV concentrations were quantified using RT-PCR-based assays. H5N1 wastewater and clinical sequences were further characterized by constructing a whole-genome maximum-likelihood phylogenetic tree. Finally, we performed variant analysis to examine amino acid substitutions detected in wastewater. Our IAV probe enrichment method and EM algorithm successfully enriched all eight segments of three circulating IAV subtypes and accurately estimated subclade relative abundances for mixed IAV samples. Seasonal human H1N1pdm09 and H3N2 were detected throughout the study period from both wastewater and clinical sequencing data, with H1N1 subclades 6B.1A.5a.2a.1 and 6B.1A.5a.2a co-circulating, and H3N2 dominated by subclade 3C.2a1b.2a.2a.3a.1. Wastewater surveillance consistently detected H5N1 clade 2.3.4.4b across three monitored wastewater sites, while clinical H5N1 detections, from anywhere in CA, were sporadic and rare. Whole-genome phylogenetic analysis revealed that wastewater H5N1 sequences clustered with reference sequences associated with dairy cow and avian infections, while all human clinical H5N1 sequences clustered exclusively with reference sequences associated with dairy cow infections. Amino acid substitutions were identified across viral segments, and no mutations associated with mammalian adaptation were observed from wastewater samples.

Competing Interest Statement

The authors have declared no competing interest.

Source: 

Link: https://www.medrxiv.org/content/10.64898/2026.06.10.26355323v1

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Immunogenicity and safety of AS03-adjuvanted A/Astrakhan/3212/2020 #H5N8 -like #influenza #vaccine in adults: Phase 1/2, observer-blinded, randomized trial

 

ABSTRACT

Influenza pandemics arise from novel influenza A viruses. Recent emergence of a new clade (2.3.4.4.b) of the highly pathogenic H5N1 in animals and humans highlighted its pandemic potential. We evaluated the immunogenicity and safety of GSK’s AS03-adjuvanted H5N8 vaccine in adults. In this phase 1/2, observer-blinded, age-stratified, randomized trial, healthy US adults (age, ≥18 y) received two intramuscular doses of hemagglutinin antigen (3.75 or 7.50 μg) with AS03A or AS03B, administered 21 d apart. Immunogenicity – seroprotection rates (SPRs), seropositivity, geometric mean titers (GMTs), geometric mean fold rise (GMFR), and seroconversion rates (SCRs) – was evaluated on day 43 using hemagglutination inhibition (HI) and microneutralization (MN) assays. Safety was monitored throughout the study. Of 520 enrolled participants, 518 were vaccinated. On day 43, the US Food and Drug Administration’s (FDA) Center for Biologics Evaluation and Research criteria for influenza vaccines were met. HI SPRs, seropositivity rates, SCRs, GMTs, and GMFR appeared to be higher in the AS03A vs AS03B group. Immune responses were generally higher in younger (aged 18–64 y) vs older (aged ≥65 y) adults. Immune responses were also detected in MN assays, with a correlation between HI and MN responses on day 43 across age groups and vaccine formulations. Safety was acceptable, with no increase in adverse events post-dose 2. Reactogenicity appeared more common in younger adults. The antigen-sparing potential of AS03 was demonstrated, with an acceptable safety profile. The benefit/risk profile was favorable for all formulations tested, including 3.75 µg AS03A (licensed in the US).

ClinicalTrials.gov registration: NCT05975840.

Source: 

Link: https://www.tandfonline.com/doi/full/10.1080/21645515.2026.2649314

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#Germany - #Influenza A #H5N1 viruses of high pathogenicity (Inf. with) (non-poultry including wild birds) (2017-) - Immediate notification

 

A flock of backyard laying hens in Bayern Region.

Source: 

Link: https://wahis.woah.org/#/in-review/7616

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Evaluation of #antiviral #treatments for highly pathogenic avian #influenza virus #infections in #feline species

 

Abstract

In 2020, highly pathogenic avian influenza (HPAI) isolates from clade 2.3.4.4b emerged in Europe and spread globally, including in bovine hosts in the USA. Viruses from this clade cause minimal disease in dairy cattle, characterized by decreased milk production but low mortality rates. Infections have also occurred in feline hosts. In contrast to cows, infection of cats (and closely related species, including skunks and foxes) can result in severe neurological signs and mortality. Documented feline H5N1 infections from clade 2.3.4.4.b have a mortality rate of approximately 80% following rapid onset of clinical signs. No antiviral compounds have been tested in an experimental feline model; however, anecdotal clinical evidence suggests early treatment with oseltamivir may improve outcomes in felines with HPAI. Here, we show the in vitro efficacy of several influenza inhibitors in feline glial astrocyte (PG-4) and kidney (CRFK) cell culture models using the clade 2.3.4.4.b virus Tx2/24 (H5N1). The neuraminidase inhibitor oseltamivir carboxylate did not effectively inhibit viral replication in either cell line. The cap-dependent endonuclease inhibitor baloxavir exhibited the strongest inhibition of this virus, with EC50 values of 30 nM in PG-4 and 1 μM in CRFK cells. Amantadine and rimantadine, M2 ion channel inhibitors, were unable to completely inhibit viral replication in either cell line at any concentration utilized. The broad-spectrum nucleoside analog GS-441524 demonstrated little to no inhibition of viral replication in either cell line. Additionally, the mutagenic NHC analogs EIDD-1931 and EIDD-2801 successfully inhibited viral replication at the maximum tested concentration of 100 μM but exhibited significant cytotoxicity. Our findings suggest that baloxavir should be considered by veterinary clinicians as the first-line drug of choice when presented with felines or other species infected with HPAI.

Competing Interest Statement

The authors have declared no competing interest.

Funder Information Declared

Cornell Feline Health Center, Ithaca, US

Source: 

Link: https://www.biorxiv.org/content/10.64898/2026.06.09.730954v1

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Avian #Influenza #Report - May 31 – June 6 '26 (Wk 23) (#HK CHP, June 9 '26): 2 new human #H5N1 virus cases in #Bangladesh, #India; 1 new case of H9N2 virus in #China

(...)

    -- Bangladesh

        ° Avian influenza A(H5N1) 

            ° Sylhet Division: 

                - The case involved a child with symptom onset on March 27, 2026.  

                - The patient was admitted to a hospital on March 28 for treatment of measles with bronchopneumonia, and was discharged on March 30. 

                - Epidemiological investigations revealed the case had exposure to household poultry.   

                - No additional cases were reported among the identified contacts.  

    -- India

        ° Avian influenza A(H5N1)

            - The case involved a child who developed symptoms and was admitted to a hospital on March 19, 2026. 

            - The patient was discharged on March 23.  

            - Epidemiological investigations revealed the case likely had indirect exposure to poultry. 

            - No additional cases were reported among the identified contacts. 

        -- China

            ° Avian influenza A(H9N2): 

                ° Yunnan Province: 

                    - A 4-year-old boy with onset on May 17, 2026. 

(...)

Link: https://www.chp.gov.hk/files/pdf/2026_avian_influenza_report_vol22_wk23.pdf

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The #canine respiratory #epithelium is a permissive #ecosystem for #influenza interspecies #transmission and emergence

 

Abstract

The outcome of virus spillover ranges from dead-end infections to pandemics and is underpinned by host-pathogen interactions as well as evolutionary and epidemiological processes. The emergence of novel influenza A viruses (IAVs) has been associated with reassortment events involving multiple species, highlighting the importance of reservoir and intermediate hosts in viral emergence. Highly pathogenic H5N1 IAVs of the 2.3.4.4b genotype have caused a panzootic affecting a broad range of mammals. The role of dogs -arguably the most popular companion animal and a natural host of IAVs- in the ecology of IAVs under this new zooepidemiological scenario is unknown. To address this, we characterised the glycome of the dog respiratory epithelium, infected canine tracheal explants with multiple IAVs (including canine H3N2 and H3N8, equine H3N8, avian H3N8 and H5N1, swine H1N1, human H1N1 and H3N2, and bovine H5N1 viruses), and determined their cellular tropism. We show that the respiratory tract of dogs presents abundant sialylated glycans known to act as IAV receptors. Further, most IAVs (including 2.3.4.4b viruses) infected and replicated in dog tracheas, targeting mainly ciliated cells. Serological testing showed evidence of influenza spillover infections in dogs from the UK. Overall, our results show that the canine respiratory tract can provide a suitable environment for the generation of new IAVs. Given the multi-host contact networks of dogs in nature, they could act as recipients, bridging hosts, and/or mixing vessels for multiple IAV lineages, playing a central role in the ecology of influenza emergence.

Competing Interest Statement

The authors have declared no competing interest.

Funder Information Declared

Medical Research Council, https://ror.org/03x94j517, MR/Y03368X/1, MC_UU_0034/2, MC_UU_0034/3

Biotechnology and Biological Sciences Research Council, BB/Y007093/1, BB/Y007298/1, BBS/E/PI/230001A, BBS/E/PI/230002A, BBS/E/PI/230002B, BBS/E/PI/230001C

Source: 

Link: https://www.biorxiv.org/content/10.64898/2026.06.04.730051v1

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