#USA, #Oregon: Avoid #contact with #bats to reduce #rabies exposure risk (Dept. of Health, July 31 '26)

 

July 30, 2026

    PORTLAND, Ore.—Oregon Health Authority (OHA) and the Oregon Department of Fish and Wildlife (ODFW) are urging people to prevent exposure to rabies while highlighting the importance of bats and other wildlife to the state’s ecosystems.

    So far, 22 bats have tested positive for rabies in 2026, according to OHA data. That means the state has matched – and is poised to surpass – its record for the number of bats that test positive for rabies in a single year. Bats have carried the rabies virus in their populations for thousands of years and are well known to carry rabies today, but generally at a very low level. Nevertheless, they account for the most human exposures to the virus more than any other species in the U.S.

    The highest number of animals testing positive for rabies since 2000 was in 2006, when 22 bats and two foxes were found to be carrying the disease. In 2023, 20 bats tested positive for the virus.

    Emilio DeBess, DVM, public health veterinarian at OHA’s Public Health Division, said the more contact someone has with bats, the higher the risk of exposure to rabies.

    “Unfortunately, when people find a dead or dying bat, they may pick it up with their hands because they want to help it, or maybe they’re just curious,” DeBess said. “When a bat or other wild animal is sick or dying with rabies, there’s an increased chance they will bite or transmit the virus in other ways.”

    Colin Gillin, DVM, ODFW state wildlife veterinarian, agrees that bats and other wildlife rarely bite people but may do so if they are sick or feel threatened. Oregon bats, in particular, eat only insects—about 1,000 insects every hour—and avoid people.

    “Bats provide important ecosystem services in Oregon, but also globally with insect control, seed dispersal, and pollination of specific plants, supporting agriculture and forest systems,” Gillin said. “And like many animals that can carry disease, bats can also prevent or suppress disease by reducing mosquitoes and other vectors that carry human and animal pathogens.”

    ° What to do if you find a bat

        § Bats are protected wildlife, which makes it illegal to harm or keep them. If you see a bat that appears to be sick:

            * Stay calm, do not touch it, and keep people and pets away.

            * When the sick or dead bat is indoors, do not release the bat. It may have exposed someone or a pet to rabies. If it is safe to do so, place a container or box over the bat.

           * When the sick or dead bat is outdoors and may have exposed someone to rabies, cover it with a box or bucket to keep it in place, if safe to do so. Finding a dead bat does not require any action unless someone was bitten or scratched before the bat died.

            * Contact your local health authority or veterinarian for your area right away to discuss potential exposures to humans or pets.

            * If there are multiple sick or dead bats observed in an area, report it to ODFW.

        § When a person or pet has been bitten or scratched by an animal that may have rabies, report this exposure immediately to your local animal regulation services or local public health authority. Seek medical care immediately from a medical provider or veterinarian.

            * Teach children to avoid all contact with bats and other wildlife.

            * Avoid bats seen in the wild, such as while hiking.

            * Make sure your dog or cats' vaccinations are up to date, whether they are indoor or outdoor pets.

            * Unvaccinated pets that come into contact with a bat may be quarantined for up to four months, or euthanized.

            * Protect your home from bats by covering vents, chimneys, and other entry points with screens.

            * If you have roosting (nesting) bats living in your attic or other areas of your house, call a wildlife control operator (WCO). ODFW is unable to respond to homeowner requests for bat removal.

(...)

Source: 

Link: https://www.oregon.gov/oha/ERD/Pages/Avoid-contact-with-bats-to-reduce-rabies-exposure-risk.aspx

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#SARS-CoV-2 #Surveillance in Free-Ranging #Wildlife in New England and #Virginia, #USA, 2022–2025

 

Abstract

Since its emergence in 2019, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has infected a wide range of animal species, including wildlife. Although SARS-CoV-2 infection has been widely reported in wildlife, particularly in white-tailed deer (WTD; Odocoileus virginianus) across the United States, data on viral circulation in New England wildlife remain limited. Here, we investigated active SARS-CoV-2 infection and serological evidence of previous exposure in free-ranging wildlife from New England and Virginia. We examined samples from 1646 animals representing 29 wildlife species, collected through wildlife rehabilitation centers, clinics, and hunter harvests in New England and Virginia between 2022 and 2025. SARS-CoV-2 RNA was detected in three WTD from Massachusetts and Vermont. Phylogeographic analysis showed that the Vermont WTD SARS-CoV-2 sequences were closely related to contemporaneous human SARS-CoV-2 sequences from the same region, consistent with a possible human-to-deer spillover event. Serological screening by ELISA detected SARS-CoV-2 reactive samples in nine individuals from three species, including Eastern cottontail (Sylvilagus floridanus), Eastern coyote (Canis latrans), and raccoon (Procyon lotor), providing putative evidence of prior SARS-CoV-2 exposure. However, neutralizing antibodies against the SARS-CoV-2 Omicron variant were detected in only a single Eastern cottontail. Overall, these findings indicate sporadic SARS-CoV-2 detection and limited serological evidence of prior exposure among wildlife sampled in New England and Virginia, and highlight the importance of continued surveillance to detect spillover events, monitor viral evolution, and assess the potential risks associated with wildlife reservoirs.

Source: 

Link: https://www.mdpi.com/1999-4915/18/8/832

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Highly Pathogenic Avian #Influenza #H5N5 in a Polar #Bear and Atlantic #Walrus, #Svalbard, 2026, with Widespread Seroconversion in Polar Bears

 

Abstract

Highly pathogenic avian influenza virus (HPAIV) subtype H5N5 was detected in a one-year-old polar bear (Ursus maritimus) and an adjacent adult Atlantic walrus (Odobenus rosmarus rosmarus), both found deceased in Raudfjorden, Svalbard. This represents the first confirmed case of HPAI in a European polar bear and the second in an Atlantic walrus. Viral genomes were nearly identical and harbored PB2-E627V, a marker associated with mammalian adaptation. Several polar bears, including the deceased individual, had previously been observed feeding on the walrus carcass. Antibodies against H5 were detected in 75% of polar bears in 2023 (n=36) and 97% in 2024-2025 (n=65), suggesting extensive circulation of HPAIV in the population following the first detections in birds in Svalbard in 2022, whereas no antibodies were detected in samples from 2014-2022 (n=243).

Competing Interest Statement

The authors have declared no competing interest.

Funder Information Declared

Project OH4Surveillance, funded by the European Union, Grant Agreement No 101132473

Morris Animal Foundation, Grant ID# D25ZO-430; KJB

Norwegian Veterinary Institute, 12311 SvalVilt

Source: 

Link: https://www.biorxiv.org/content/10.64898/2026.07.20.739480v1

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Highly Pathogenic Avian #Influenza #H5N1 in South #America, 2022–2025: Spread, Affected Species, and Southward Expansion into the #Antarctic Region

 

Abstract

The H5N1 highly pathogenic avian influenza (HPAI) virus has caused severe global losses, reaching South America in 2022 and Antarctica in 2024. Here, we synthesize outbreak reports submitted to the World Organization for Animal Health by South American countries and overseas territories in this continent, and document the virus’s unprecedented expansion into Antarctica, affecting wild birds, wild mammals, and domestic poultry. Phylogenetic and time-calibrated Bayesian analyses were performed on available genomic sequences. Over 6 million domestic birds were lost, mostly from commercial operations. Of the 11 South American countries and overseas territories that reported H5N1 to WOAH, 10 reported infections in wild birds, spanning 104 species, 59.62% of which are migratory and predominantly non-trans-equatorial. Marine mammal outbreaks followed wild bird detections, with the South American sea lion (Otaria flavescens) being the most reported species. Several Antarctic bird species with migratory behavior were also reported in South America. Genomic analyses revealed multiple introduction events, regional viral diversification, and patterns consistent with repeated cross-species spillover events. These findings highlight H5N1’s extensive ecological reach in the Southern Hemisphere and underscore the urgent need for a One Health approach that strengthens wildlife and backyard-poultry surveillance, alongside coordinated regional action to control and prevent further HPAI spread.

Source: 

Link: https://www.mdpi.com/1999-4915/18/7/764

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Inter-population #connectivity of southern elephant #seals and the likely intra-species #transmission #pathways of high pathogenicity avian #influenza

 

Abstract

High Pathogenicity Avian Influenza (HPAI) H5N1 clade 2.3.4.4b has spread beyond birds to affect seals across the Southern Ocean and sub-Antarctic region, with southern elephant seals (Mirounga leonina) particularly devastated. The virus, likely introduced via spillover from infected migratory birds, has killed tens of thousands of adult seals and pups throughout most of their range, though Macquarie Island remains unaffected so far. We used twenty years of elephant seal movement data from the southern Indian and Pacific oceans to assess whether seal-to-seal transmission could spread HPAI H5N1 between breeding colonies, despite the vast distances separating them (Marion Island, Iles Crozet, Iles Kerguelen, and Macquarie Island). There was substantial overlap in seals' at-sea distributions during their winter post-moult trips, when seals travel for weeks at average speeds of 3.5 km/h. Two transmission pathways were examined: (1) terrestrial "stepping stone" routes, where infected seals could pass the virus between colonies during short intervals to remain infectious were feasible from Marion Island to Kerguelen but not from Kerguelen to Macquarie Island; and (2) at-sea encounters between seals, which occurred frequently enough to enable transmission. The findings suggest that once established at Macquarie Island, the virus could potentially spread further to New Zealand's sub-Antarctic islands and mainland New Zealand. While seal-to-seal transmission appears possible, we conclude this is unlikely. Nonetheless, understanding at-sea contact rates enhances knowledge of H5N1 epidemiology and demonstrates the value of combining long-term population monitoring with movement data to understand wildlife disease dynamics.

Competing Interest Statement

The authors have declared no competing interest.

Funder Information Declared

Integrated Marine Observing System, https://ror.org/010x3gp67

CNRS

Source: 

Link: https://www.biorxiv.org/content/10.64898/2026.07.07.737127v1

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#Filovirus #Surveillance in Communities Bordering Equatorial Guinea, #Marburg #Outbreak, #Cameroon, 2023

 

Abstract

After the 2023 Equatorial Guinea Marburg virus (MARV) outbreak, surveillance of 181 persons in southern Cameroon detected MARV antibodies in 3 persons and Ebola virus antibodies in 7. Testing of 289 captured bats, including 158 Rousettus aegyptiacus bats, did not detect MARV RNA. Enhanced surveillance for regional filovirus spillover risks is warranted.

Source: 

Link: https://wwwnc.cdc.gov/eid/article/32/8/26-0117_article

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#Genomic #Surveillance Uncovers the Silent #Spread of Avian #Influenza Virus #H5N1 2.3.4.4b Among Wild #Birds and #Mammals Along #Brazil’s Southern Coast

 

Abstract

Avian influenza viruses (AIVs) are widely distributed and have a wide range of hosts. Recently, the number of cases of infection associated with the circulation of highly pathogenic avian influenza H5N1 2.3.4.4b has raised concerns about its high transmission capacity in birds and mammals. This study analyzed swabs from bird and mammal species from the coast of Paraná and the northwest region of São Paulo, Brazil, for the presence of AIV in animals that did not present clinical or histopathological lesions of infection that indicated the need for molecular characterization during monitoring. Of the 661 animals analyzed, three tested positive, two of which were birds (Sula leucogaster and Thalasseus acuflavidus) while one was a mammal (Otaria flavescens) (0.45%, CI 95%: 0.16–1.33). A complete genome sequence of H5N1 AIV was obtained from a brown booby (Sula leucogaster) from the Paraná coast (GISAID accession number: EPI_ISL_1897537). Our study reinforces the importance of continuous genomic surveillance, especially in AIV hosts that do not show signs of infection, to enhance the One-Health assessment approach.

Source: Viruses, https://www.mdpi.com/journal/viruses

Link: https://www.mdpi.com/1999-4915/18/7/738

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Maintenance of #Hokkaido virus, a genotype of #Orthohantavirus puumalaense, in the #rodent host Myodes rufocanus bedfordiae under natural conditions

 

ABSTRACT

A variety of orthohantaviruses (family Hantaviridae) have preferred natural host species, with transmission among hosts generally thought to occur through direct physical contact and inhalation of virus-contaminated excreta, although the infection to the other species occasionally occurs. Despite extensive experimental studies, the mechanisms of orthohantavirus maintenance and transmission under natural conditions remain unclear. In this study, field surveys were conducted in a forest in Tobetsu, Hokkaido, Japan, between 2022 and 2025 to capture gray red-backed voles (Myodes rufocanus bedfordiae), the natural host of Hokkaido virus (HOKV), a genotype of Orthohantavirus puumalaense. Among 199 captured rodents, 23 were positive for HOKV infection. Five individuals were positive for viral RNA but negative for anti-HOKV IgG antibodies on ELISA and IFA and exhibited low neutralizing antibody titers and low IgG avidity indexes (≤26%), suggesting acute infection. In contrast, 18 individuals were positive for viral RNA and showed high antibody titers on ELISA, IFA, and neutralization tests, as well as high IgG avidities (≥64%); these individuals were considered persistently infected. High levels of viral RNA and antigens were consistently detected in the lungs, kidneys, and spleen during both potential acute and persistent phases of HOKV infection by quantitative PCR and immunohistochemistry. Infectious HOKV was also recovered from oral swabs (8/8), urine (3/6), and feces (4/6) of individual rodents captured in 2024. These findings showed that HOKV can persist at high viral loads in host organs and be excreted throughout the course of infection, contributing to the long-term maintenance of orthohantavirus in natural host populations.

Source: Journal of Virology, https://journals.asm.org/journal/jvi

Link: https://journals.asm.org/doi/10.1128/jvi.00321-26

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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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#Biodiversity and emerging infectious #threats: the microbial dark matter of Southwest #China

 

Abstract

Southwest China is a global biodiversity hotspot, and its complex and diverse ecosystems harbor vast amounts of “microbial dark matter.” This paper systematically examines the distribution characteristics of microbial dark matter in hosts such as arthropods, mammals, and birds, as well as in environments including soil, hot springs, and high-altitude lakes, with a particular focus on the cross-species transmissibility and pathogenic potential of emerging pathogens. Research indicates that new microbial species in the Southwest exhibit significant geographic concentration and host specificity: Yunnan Province is a core hotspot, while the Tibet Autonomous Region contributes a wealth of microbial resources due to its extreme environments, with arthropods and mammals accounting for the highest proportion of novel species. Regarding public health risks, eight novel pathogens with evidence of human infection have been identified, spanning the three major groups of viruses, bacteria, and parasites. The cross-species transmission potential of some pathogens (such as DPRV rhabdovirus, PPV arenaviridae, Luxi hantavirus, Banna virus and a novel Babesia species) has been confirmed through serological surveys or molecular testing. Deepening the exploration of microbial dark matter and risk early warning in this region will provide critical scientific support for public health safety monitoring.

Source: 

Link: https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2026.1846062/full

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#Nipah Virus Shedding in #Urine from Fruit #Bats, #SriLanka, 2018–2019

 

Abstract

Nipah virus causes outbreaks in humans with high case-fatality rates. In this study, we confirmed the presence of Nipah virus in Sri Lanka in Pteropus medius fruit bats, one of the known natural reservoir species. Sequences we generated were genetically related to Nipah virus strains from outbreaks in southern India.

Source: 

Link: https://wwwnc.cdc.gov/eid/article/32/7/25-1567_article

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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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Data #gaps of international #databases on HPAI #H5 in #wildlife in the #Americas: implications for #surveillance, research, and #conservation

 

Abstract

Global efforts to prevent and mitigate the impacts of high pathogenicity avian influenza (HPAI) H5 on domestic animals, humans, and wildlife rely on timely and transparent information that is both accurate and interpretable across countries and sectors. International epidemiological and genomic databases, such as the World Animal Health Information System (WAHIS), the Global Animal Disease Information System (EMPRES-i+), the Global Initiative on Sharing All Influenza Data (GISAID), and the National Center for Technological Bioinformation Virus Portal (NCBI) provide essential information for surveillance, research, and decision-making. To evaluate how well these resources capture recent wildlife impacts, we consolidated information from these databases and complementary public sources including government reports, scientific literature, and news articles, on wildlife mortality associated with HPAI H5 in the Americas from November 2021 to July 2024. The consolidated dataset comprised 615,883 wild birds (287 spp.) and 63,409 wild mammals (39 spp.). In comparison, WAHIS represented 16,902 wild birds (261 spp.) and 6,323 wild mammals (31 spp.) while EMPRES-i+ captured a substantially smaller portion of affected host diversity for both wild birds (105 spp.) and wild mammals (27 spp.). Genomic databases (GISAID and NCBI) represented 7,027 whole genome equivalents of H5 viruses from wild birds (175 spp.) and 371 from wild mammals (26 spp.). These discrepancies indicate that international databases, while essential, provide an incomplete picture of HPAI impacts on wildlife, with significant geographic and taxonomic asymmetries attributable to differences in surveillance capacity, reporting practices, sequencing effort, and data-sharing pathways. Studies and management strategies relying on these resources without complementary validation may therefore mistake data gaps for real-world epidemiological patterns. Strengthening data reporting standards, improving validation procedures, and integrating international databases with national reports, scientific publications, and other sources will enhance the reliability of epidemiological analyses and support more effective One Health surveillance, risk assessment, and conservation action.

Competing Interest Statement

The authors have declared no competing interest.

Source: 

Link: https://www.biorxiv.org/content/10.64898/2026.05.30.728949v1

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Predicting #Influenza Virus #Host #Tropism and Zoonotic #Spillover #Risk from #Protein Sequences

 

Abstract

Novel infectious diseases, predominantly originating from non-human animals, pose a significant threat to global public health and economic stability. Avian influenza virus presents an especially significant challenge due to its high mortality rates and spillover capability into new host species. Recent H5N1 spillover events into poultry and cattle resulted in massive economic burden and increased human health risk. Traditional methods of disease surveillance rely on reactive case detection and pathogen characterization, providing insufficient lead time for effective intervention. Computational tools that allow efficient and proactive prediction of zoonotic potential are critical in mitigation of influenza outbreaks and identification of strains with human spillover risk. Existing models predicting influenza virus subtypes or host have been developed; however, the complexity of spillover events, including the non-binary nature of zoonotic potential, limits the capabilities of these models. In the approach reported here, rich protein language model embeddings were generated from ESM-2 for each protein in influenza virus strains and used to predict the protein host tropism probabilities across nine animal families. The protein host tropism model achieved weighted precision and recall scores of 0.95 and 0.95, respectively. We then constructed a zoonotic risk prediction model using the outputs from the protein host tropism prediction model to classify the strains into six classifications: avian, mammal, human, avian-to-human zoonotic, avian-to-mammal zoonotic, or mammal-to-human zoonotic. The average weighted precision and recall scores for this model were 0.90 and 0.90, respectively. This framework advances the prediction of influenza zoonotic risk by being agnostic to influenza subtype, incorporating non-human mammals and mammal zoonotic spillover classifications, and using the full influenza proteome to capture the complexity of spillover dynamics.

Competing Interest Statement

The authors have declared no competing interest.

Source: 

Link: https://www.biorxiv.org/content/10.64898/2026.05.21.726772v1

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#Coronavirus #diversity and #SARS-CoV-2 #exposure at the #wildlife – #human interface in Northern #Italy

 

Abstract

Background

Members of the Coronaviridae family infect humans as well as domestic and wild animals. Over the past three decades, three members of this family, all with zoonotic origins, have caused significant epidemics or pandemics (SARS, MERS, and COVID-19). Despite the spread of SARS-CoV-2 being primarily driven by human-to-human transmission, various animal species are susceptible to infection and may contribute to viral circulation. Aim of this work was to monitor coronavirus (CoV) infections in wild mammals in the Emilia-Romagna region (RER), Italy, using a combined approach of molecular screening for viral RNA detection and serological testing for anti-SARS-CoV-2 antibodies.

Methods

Respiratory and gastrointestinal tissue samples were collected from wild animal carcasses between 2022 and 2024. Samples were tested for SARS-CoV-2 using two RT-qPCR assays targeting the E and N genes, and for other CoVs using a nested pan-coronavirus RT-PCR followed by Sanger sequencing of positive samples. Additionally, serum samples obtained from blood, cardiac clot, or thoracic exudate were screened for antibodies against the SARS-CoV-2 nucleocapsid (N) protein, with positive samples subsequently confirmed by an ELISA targeting antibodies to the receptor-binding domain (RBD) of the Spike (S) protein, focused on variants circulating during the study period.

Results

Molecular analyses were performed on 2,238 animals, all of which tested negative for SARS-CoV-2, while 90 (79% hedgehogs) tested positive for CoVs. Among these, most sequences were consistent with coronaviruses typically reported in the respective host species. However, some exceptions – such as Betacoronavirus erinacei in fox, porcupine, hare, and roe deer, and EmbeCoV-related sequences in a porcupine – warrant further attention. Suitable serum samples were available from 1,751 animals. Overall, 65 animals tested positive for anti-N antibodies, 31 of which (22 foxes, 4 badgers, 2 hedgehogs, 1 roe deer, 1 wolf, 1 rat) were subsequently confirmed by an anti-RBD ELISA.

Conclusions

This study provides an overview of CoVs circulation among wild mammals in RER, supporting the role of hedgehogs as reservoirs and identifying some species with evidence of exposure to SARS-CoV-2. Certain unexpected findings highlight the need for further investigations to clarify the potential for cross-species transmission.

Source: 

Link: https://link.springer.com/article/10.1186/s12985-026-03193-3

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Updated joint FAO/WHO/WOAH public health #assessment of recent #influenza #H5 virus #events in #animals and #people, based on data as of 1 March '26 (18 May 2026)

Key points 

    -- Based on currently available information, Food and Agriculture Organization of the United Nations (FAO)/World Health Organization (WHO) / World Organisation for Animal Health (WOAH) assess the global public health risk posed by Gs/Gd-like high pathogenicity avian influenza (HPAI) A(H5) viruses as low. 

    -- The risk of infection for occupationally or frequently exposed persons (e.g., with backyard poultry) is assessed as low to moderate depending on local epidemiologic conditions and the risk mitigation and hygiene measures in place. 

    -- Transmission among animals continues and sporadic human infections at the human-animal-environment interface continue to be reported. 

    -- While additional human infections associated with exposure to infected animals or contaminated environments are expected, the overall global public health impact of such infections is currently considered minor. 

    -- The assessment may change rapidly as new epidemiological or virological information becomes available. 

    -- This joint FAO/WHO/WOAH risk assessment updates the transmission risk using new global information available since the previous assessment of 28 July 2025. 

    -- Given the potential risk to human health and the wide-ranging impacts on wild birds and mammals, poultry, livestock and other animal populations, timely notification to global authorities and the application of a One Health approach remain essential to monitor and characterize virus circulation, limit transmission within species and between species, reduce spread among animals, and prevent human infections. 

Infections in animals  

    -- To date, HPAI A(H5) viruses have been detected in birds and/or mammals across all continents except Oceania. 

    -- The predominant H5 virus clades currently circulating worldwide derive from clades 2.3.2.1 and 2.3.4.4. 

    -- Between 1 July 2025 and 1 March 2026, an additional 185 A(H5N1) events{i} in animals (including birds and bovines) have been reported to WOAH. 

    -- Of these, 1204 outbreaks occurred in poultry (of any farming system), 6326 outbreaks in wild birds and nine outbreaks occurred in bovines.  

H5 clade 2.3.2.1 viruses 

    -- Between 1 July 2025 and 1 March 2026, A(H5N1) clade 2.3.2.1a viruses were detected in poultry in Bangladesh and India, while A(H5N1) clade 2.3.2.1e viruses were detected in poultry in Cambodia 

H5 clade 2.3.4.4b viruses 

    -- Detections of A(H5) in wild and domestic mammals and wild and domestic birds continued to be reported in many countries worldwide. 

    -- During the period of September-November 2025, Europe experienced an exceptional and early season and a high incidence of HPAI A(H5) activity in wild birds, with more than 3200 detections reported across 28 countries. 

    -- This represents a ten-fold increase compared to the same period in 2024. 

    -- Based on genetic data available so far, the A(H5N1) HPAI viruses identified in Europe all fall into clade 2.3.4.4b, and the majority belong to the genotype EA-2024.DI2.12,{3} 

    -- This surge has disproportionately affected migratory waterfowl and colonial species, with widespread A(H5N1) virus infections confirmed in key migratory hosts (e.g., Eurasian wigeons, Northern pintails, Mute swans, Greylag geese) and severe mass mortality events in Eurasian cranes (Grus grus).{4}  

    -- In Africa, poultry outbreaks of A(H5N1) clade 2.3.4.4b viruses have been reported in Nigeria and South Africa since September 2025. 

    -- Several other countries in sub-Saharan Africa consider HPAI to be present in their territories. 

    -- Detections of A(H5N1) were also made in wild birds in Namibia and South Africa. 

    -- A(H5N1) clade 2.3.4.4b viruses are considered endemic in Egypt’s poultry populations.   

    -- In Asia, clade 2.3.4.4b viruses have been reported in several countries. 

    -- In India, recent poultry outbreaks have involved A(H5N1), while in Kazakhstan, A(H5N1) was detected in wild birds. 

    -- In the Republic of Korea, detections include A(H5N1), A(H5N6), and A(H5N9), while in Japan A(H5N1) and A(H5N5) viruses have been reported. 

    -- In North America, substantial activity of clade 2.3.4.4b A(H5) viruses has continued since the last assessment. 

    -- In the United States of America, more than 3700 A(H5) detections in wild birds and over 400 A(H5) HPAI outbreaks in poultry were reported, while Canada reported nearly 500 A(H5N1) detections in wild birds and over 80 A(H5) HPAI outbreaks in poultry.{5,6} 

    -- A(H5N1) detections in terrestrial and marine mammals have also been reported. 

    -- Notably, A(H5N1) clade 2.3.4.4b was detected for the first time in northern elephant seals in February 2026 in California, involving a virus of the A3 genotype.{7} 

    -- In central America, Mexico reported H5N1 outbreaks in backyard poultry in October 2025 and A(H5N1) detections in wild birds in November. 

    -- A(H5N1) detections of American genotype D1.1 viruses were reported in domestic birds in the Cayman Islands and Guatemala during the second half of 2025. Genotype D1.1 was the most frequently detected A(H5N1) genotype in North America in 2025, affecting wild birds, poultry and multiple mammalian species, including wild and domestic felids and marine mammals. 

    -- A(H5N2) clade 2.3.4.4b viruses belonging to the K.5 genotype were detected in poultry in Mexico.  

    -- In South America, A(H5N1) has continued to spread, with detections in both poultry and wild birds across multiple countries. 

    -- In late 2025, A(H5N1) outbreaks were reported from Argentina, Brazil and Colombia. 

    -- Where sequence data are available, viruses belong to clade 2.3.4.4b.{8} 

    -- In 2026, additional outbreaks occurred across the region. HPAI A(H5) outbreaks occurred in Peru in backyard poultry and in Uruguay in wild birds, although detailed genetic information for these events is not yet available. 

    -- Between 1 February and 1 March 2026, Argentina detected at least 12 A(H5N1) events across domestic and wild birds, while further A(H5N1) outbreaks occurred in backyard and wild birds in Brazil, and in backyard birds in Colombia and Peru.  

    -- Although the full extent of ongoing circulation and establishment in wild bird populations across South America remains uncertain, evidence suggests that A(H5N1) viruses circulating have continued to diversify through reassortment. 

    -- Viruses detected in Brazil in mid- to late 2025 belonged to two distinct genotypes, K.8 and N.1. 

    -- The K.8 genotype is related to “triple reassortant” viruses{9} identified in Argentina in early 2025, combining North American B3.6- and B3.13-like genomes but with multiple internal gene segments derived from South American low pathogenicity avian influenza viruses (LPAIVs).{10,11} 

    -- Its continued presence is consistent with sustained regional spread. 

    -- In contrast, the N.1 genotype clusters with recent North American B3.2 viruses but contains a PB2 segment derived from South American low pathogenicity avian influenza viruses. 

    -- This suggests a separate, more recent introduction of A(H5N1) viruses to South America, followed by reassortment with locally circulating viruses.{12} 

    -- In the Antarctic peninsula and sub-Antarctic islands, A(H5N1) clade 2.3.4.4b viruses have been repeatedly detected in the region, including in sea birds such as skuas and penguins, following their introduction during the 2023–2024 austral summer.{13} 

    -- Detections in wild birds and mammals in the region have continued through 2025–2026. This includes outbreaks in additional sub-Antarctic territories, such as Heard Island, where A(H5N1) was detected in Antarctic fur seals, gentoo penguins and southern elephant seals.{14,15} 

    -- This follows initial detections in southern elephant seals on an earlier voyage in October 2025. 

    -- There was no further evidence of ongoing mass mortality detected on this second voyage in January 2026. 

    -- Further sequencing and phylogenetic analysis are being undertaken. 

    -- The extensive circulation of clade 2.3.4.4b A(H5) viruses in wild and domestic bird populations has resulted in multiple spillover events into wild terrestrial mammals, both carnivorous and omnivorous, wild marine mammals, and domestic cats and dogs.{16} 

    -- Amino acid changes potentially associated with increased virulence, transmission, or adaptation to mammalian hosts have been sporadically identified.{17,18,19}  

    -- Since 2024 and as of 1 March 2026, 1088 dairy herds in 19 states of the United States of America have tested positive for A(H5N1). 

    -- Since the last assessment of 28 July 2025, 14 additional A(H5N1) detections have been reported in the country, with the latest detection confirmed in December 2025 in Wisconsin.{20} 

    -- Analyses of virus sequence data suggest that there have been at least four independent spillovers of A(H5N1) into dairy cattle with the most recent occurring in December 2025.{21} 

    -- In January 2026, Netherlands (Kingdom of the) reported the detection of A(H5N1) HPAI antibodies in the milk of a dairy cow at a dairy farm in Friesland Province, following the investigation of a cat living on that dairy farm that died from an A(H5N1) infection.{22} 

    -- The virus detected in the cat belonged to clade 2.3.4.4b genotype EA-2024.DI2.1—which is distinct from the B3.13 and D1.1 genotypes detected in dairy cattle in the United States of America. No evidence of active infection was found in  the herd, but antibodies were later detected in four additional cows on the same farm, therefore, they do not constitute a case according to the WOAH case definition.  

    -- Mammalian detections of A(H5N5) clade 2.3.4.4b viruses have also been reported in recent years, particularly those belonging to the A6 genotype. 

    -- Since 2023, detections have been reported in terrestrial carnivora (northern racoon, striped skunk, red fox, Eurasian lynx, Eurasian Otter, American mink, Arctic fox and domestic cats) across North America and Europe and in marine mammals. 

    -- For the latest information on avian influenza situation in animals worldwide, see the FAO Global Avian Influenza Viruses with Zoonotic Potential situation update and the WOAH situation reports on HPAI, as well as WOAH’s World Animal Health Information System. 

Detections in humans 

    -- Since the last joint assessment of July 2025 and as of 1 March 2026, nine additional human cases of A(H5N1) virus infections, and single cases of A(H5), A(H5N2), A(H5N5) virus infections have been detected (based on date of reporting) in Bangladesh, Mexico and the United States of America. 

    -- Eight A(H5N1) cases were detected in Cambodia, and one was detected in Bangladesh. 

    -- All cases reported direct or indirect exposure to domestic birds or contaminated environments. 

    -- No human-to-human transmission was suspected associated with these confirmed cases. 

    -- The viruses from two cases in Bangladesh belong to clade 2.3.2.1a viruses, viruses from six of the cases from Cambodia belong to clade 2.3.2.1e, and viruses from the cases in Mexico and the United States of America belong to clade 2.3.4.4b.  

Virus characteristics  

    -- Routine monitoring and screening of viral sequences from birds have rarely identified markers of mammalian adaptation in A(H5) viruses, and when detected, these have primarily involved the polymerase proteins. 

    -- Such mutations have been observed more frequently in viruses isolated from mammals. 

    -- The PB2 D701N amino acid mutation has been identified in genotype D1.1 viruses detected in poultry (including chickens and turkeys), wild birds, cats, dairy cattle and wild mammals such as red foxes.{23} 

    -- The PB2 E627K mutation has been detected in some B3.13 viruses identified in dairy cattle and in clade 2.3.2.1 and 2.3.4.4 A(H5) viruses detected in poultry, cats and wild birds across multiple regions. 

    -- Some genetic markers in A(H5N1) virus sequences from human cases have been linked to potentially lower lab-based susceptibility to common antivirals like oseltamivir or baloxavir marboxil; the clinical significance of some of these markers remains uncertain.{24} 

    -- Experimental studies with A(H5N1) clade 2.3.4.4b viruses have generally not demonstrated efficient transmission via respiratory droplets.{25,26,27,28,29,30,31} 

    -- Ferret studies conducted by the US CDC using a D1.1 A(H5N1) virus (A/Washington/239/2024) did not show respiratory droplet transmission.{32} 

    -- Overall, currently circulating A(H5N1) viruses would require additional genetic changes to acquire efficient human-to-human transmission via respiratory droplets, consistent with the current low public health risk. 

    -- Based on limited seroprevalence information available on A(H5) viruses, human population immunity against the HA of A(H5) viruses is expected to be minimal; human population immunity targeting the N1 neuraminidase is found to be present although the impact of this immunity is yet to be understood.{33}  

Candidate vaccine viruses (CVV) 

    -- The WHO Global Influenza Surveillance and Response System (GISRS), in collaboration with animal health partners (FAO, WOAH, OFFLU (Joint WOAH-FAO network of expertise on animal influenza), continue to evaluate candidate vaccine viruses for pandemic preparedness purposes both biannually and on an ad hoc basis. 

    -- Regular genetic and antigenic characterization of contemporary zoonotic influenza viruses are published here with the most recent update on A(H5) CVVs published in February 2026 following the WHO Consultation on the Composition of Influenza Virus Vaccines for Use in the 2026-2027 Northern Hemisphere Influenza Season.  

 

Assessment of current public health risk posed by influenza A(H5N1) viruses{34} 

    -- Despite continued detections of A(H5) viruses in animals and ongoing human exposure at the human-animal-environment interface, relatively few human infections have been reported to date. 

    -- Since the beginning of 2021, the vast majority of reported human A(H5) infections have been associated with direct or indirect exposure to infected animals such as milking cows on an infected dairy farm or participating in mass culling and disposal events at poultry farms, or contaminated environments, such as live poultry markets, or beaches with sick and dying wild birds and marine mammals.{35,36} 

    -- Illness severity has ranged from mild to fatal. 

    -- To date, no human-to-human transmission has been identified through epidemiologic, virologic and serologic investigations, although investigations for some of cases are ongoing. 

    -- Current evidence indicates that these viruses remain avian-adapted, without established mammalian adaptive mutations or the capacity for sustained human-to-human transmission.  

    -- Based on currently available information, FAO/WHO/WOAH assess the global public health risk posed by currently circulating influenza A(H5) viruses as low and unchanged from the previous risk assessment, while the risk of infection for occupationally or frequently exposed persons remains low to moderate depending on local epidemiological conditions and mitigation measures in place. 

    -- However, as influenza viruses are constantly evolving and spreading in animal populations, zoonotic influenza risk assessments require continuous review and may change rapidly. 

    -- WHO, together with FAO and WOAH, continues to evaluate A(H5) viruses closely and will re-assess the risk associated with the currently circulating A(H5) viruses as more information becomes available. 

    -- Further antigenic characterization of A(H5) viruses, including in relation to the existing CVVs, and development of specific reagents are being prioritized at the WHO Collaborating Centres and Essential Regulatory Laboratories of GISRS in collaboration with public health, animal health, and veterinary sector colleagues. 

Recommended actions  

    -- It is recommended that Member States and national authorities: 

        • increase surveillance and vigilance, and assess the risk in human populations, especially amongst occupationally exposed persons, for the possibility of zoonotic infections, particularly through National Influenza Centres (NICs) and other influenza laboratories associated with GISRS, using such methods as active case finding and molecular and serologic methods; 

        • reduce the risk among occupationally exposed persons by reducing environmental exposures and providing adequate and appropriate personal protective equipment; and 

        • conduct epidemiological investigations including case finding around suspected and confirmed human cases to determine if there are additional cases or indications of humanto-human transmission.  

    -- Under the International Health Regulations (IHR) (2005),{37} States Parties are required to notify WHO within 24 hours of any laboratory-confirmed case of human influenza caused by a new subtype according to the WHO case definition.{38} 

    -- WHO has published the case definition for human infections with avian influenza A(H5) virus requiring notification under IHR (2005).{39}  

    -- Avian influenza is a WOAH-listed disease. Based on Chapter 10.440 of the Terrestrial Animal Health Code, three categories of avian influenza should be notified to WOAH by national Veterinary Authorities through WAHIS. It includes infection with HPAI in poultryii, infection of birds other than poultry including wild birds, and infection of domestic and captive wild birds with low pathogenicity avian influenza (LPAI) viruses having proven natural transmission to humans associated with severe consequences. 

    -- Member States and national authorities are also recommended to: 

        • conduct joint epidemiological investigations in and around suspected and confirmed outbreak areas in animals to determine the extent of spillover; 

        • increase surveillance, including joint/collaborative genomic surveillance, and sharing surveillance data applying One Health principles;  

        • timely reporting efforts for the early detection of A(H5) influenza viruses in domestic birds, wild birds and wild mammals{41}; 

        • include infection with an A(H5) influenza virus as a differential diagnosis, in non-avian species, including cattle, swine and other livestock and farmed domestic and wild animal populations, with high likelihood of exposure to A(H5) viruses; 

        • implement preventive and early response measures to break the chain of infection among domestic animals (for example, poultry and dairy cattle), including considering the use of vaccination to reduce circulation in poultry as per national policies and according to guidance provided by animal health organizations{42,43}; 

        • promptly report high pathogenicity avian influenza (HPAI) events in all animal species, including cattle (according to the WOAH case definition{44}) and other domestic and wild mammals, to WOAH and other international organizations such as FAO;  

        • conduct genetic sequencing and share genetic sequences of influenza viruses and associated metadata in publicly available databases in a timely manner; 

        • protect animals by mitigating the risk of introduction and spread of the disease through implementation and/or strengthening biosecurity in livestock holdings/premises and along the value chain; 

        • protect persons by employing good production and hygiene practices when handling animals and animal products; and 

        • protect persons in contact with suspected/infected animals by providing appropriate personal protective equipment and communicating and educating on the importance and proper use of personal protective equipment and providing information and access to testing. 

    -- Additional sets of recommendations related to avian influenza viruses with zoonotic potential can be found here: 

        • FAO and WOAH Global strategy for the prevention and control of high pathogenicity avian influenza (2024–2033) 

        • Recommendations from the FAO Global Dialogue - Tackling high pathogenicity avian influenza together. Foz do Iguaçu, Brazil – 11 September 2025 

        • FAO recommendations for Global Avian Influenza Viruses with Zoonotic Potential 

        • FAO Recommendations for the surveillance of influenza A(H5N1) in cattle. With broader application to other farmed mammals 

        • WOAH Surveillance of High Pathogenicity Avian Influenza for Smallholder Poultry Systems in Resource-Limited Settings 

        • WHO Practical interim guidance to reduce the risk of infection in people exposed to avian influenza viruses 

        • WHO Surveillance for human infections with avian influenza A(H5) viruses: objectives, case definitions, testing and reporting 

        • WHO Considerations for the use of human A(H5) influenza vaccines during non-pandemic period 

        • WHO guidance on the use of licensed human influenza A(H5) vaccines for the interpandemic and emergence periods 

    -- Additional studies/surveillance, applying One Health principles are warranted, which could provide information to enhance confidence in the risk assessment. 

    -- These may include serological studies in high-risk animal populations, in high-risk human populations, and epidemiological investigations.  

    -- Anyone who may have been exposed to infected or potentially infected animals or contaminated environments should be advised to promptly seek health care if they feel unwell, and to inform their health care provider of their possible exposure. 

    -- Following prompt testing, early and appropriate clinical management should be initiated, and precautionary measures put in place to assess and prevent potential further spread among humans and animals.

    -- Clinicians should also be alerted to potential zoonotic infection in patients with an exposure history to birds or animals especially in areas where A(H5) viruses are known or suspected to be circulating in animals but also in areas where surveillance in animals may be limited.  

    -- Routine epidemiologic and virologic surveillance for influenza should be conducted ideally yearround using a standard case definition in health care facilities according to WHO guidance.{45}  

    -- Timely sharing of information and sequence data from both the human and animal health sectors from all regions should continue to be strongly recommended and is critical for rapid and robust joint risk assessment. 

    -- The rapid sharing of virus materials with WHO Collaborating Centres of GISRS continues to be essential to conduct a thorough risk assessment and develop or adjust targeted response measures. 

    -- The Tool for Influenza Pandemic Risk Assessment (TIPRA) provides an in-depth assessment of risk associated with some zoonotic influenza viruses – notably the likelihood of the virus gaining human-to-human transmissibility, and the impact should the virus gain such transmissibility. 

    -- TIPRA maps relative risk amongst viruses assessed using multiple elements.{46} 

    -- Data pertaining to the risk elements within TIPRA should be generated and shared with WHO.  

    -- Efforts to reduce human exposure to birds, livestock, and other mammals infected with or potentially infected with avian and other animal influenza viruses should be implemented and enhanced to minimize the risk of zoonotic infections. 

    -- Individuals with activities that involve exposure to infected animals and/or contaminated environments are at higher risk and should take necessary precautions to prevent infection. 

    -- Those who are exposed to potentially infected animals should have access to, be trained in their use under different environmental conditions, and wear personal protective equipment including eye protection.{47} 

    -- If they develop respiratory symptoms or conjunctivitis, they should be rapidly tested, and precautionary infection control measures should be put in place to prevent potential further spread among humans and to animals. 

    -- For detailed guidance on treatment, refer to relevant global and national guidance.{48} 

    -- Some manufacturers have initiated production of an A(H5) human vaccine that matches current circulating strains. 

    -- Updated WHO guidance on the use of licensed human influenza A(H5) vaccines for the interpandemic and emergence periods were published in December 2025.{49} 

    -- FAO, WHO and WOAH advise consuming pasteurized milk, instead of raw/unpasteurized milk. Due to the potential health risks from many dangerous zoonotic pathogens, raw/unpasteurized milk consumption should be avoided.{50} 

    -- If pasteurized milk is not available, heating raw milk until it boils makes it safer for consumption.{51}  

___

{i} An event includes all related epidemiologically related outbreaks reported from the time of the immediate notification through to the final report. Separately the total number of outbreaks is also stated. 

{ii} All birds reared or kept in captivity for the production of any commercial animal products or for breeding for this purpose, fighting cocks used for any purpose, and all birds used for restocking supplies of game or for breeding for this purpose, until they are released from captivity. Birds that are kept in a single household, the products of which are used within the same household exclusively, are not considered poultry, provided that they have no direct or indirect contact with poultry or poultry facilities. Birds that are kept in captivity for other reasons, including those that are kept for shows, racing, exhibitions, zoological collections and competitions, and for breeding or selling for these purposes, as well as pet birds, are not considered poultry, provided that they have no direct or indirect contact with poultry or poultry facilities. 

References 

{1} WHO. Genetic and antigenic characteristics of zoonotic influenza A viruses and development of candidate vaccine viruses for pandemic preparedness. February 2026 (https://cdn.who.int/media/docs/default-source/vcm-northern-hemisphere-recommendation-20262027/c.-27-feb-2026_zoonotic_vaccinvirus-update.pdf?sfvrsn=8532151e_5). 

{2} European Food Safety Authority (EFSA), European Union Reference Laboratory (EURL) for Avian Influenza, Ducatez M, Fusaro A, Gonzales J L, Kuiken T, et al. Unprecedented high level of highly pathogenic avian influenza in wild birds in Europe during the 2025 autumn migration. EFSA Journal 2025;23(11):9811, 9 pp (https://doi.org/10.2903/j.efsa.2025.9811). 

{3} EURL. Avian flu data portal. 2026 (eurlaidata.izsvenezie.it/epidemio.php). 

{4} EFSA, European Centre for Disease Prevention and Control (ECDC), EURL for Avian Influenza; Buczkowski H, Ducatez M, Fusaro A, et al. Avian influenza overview September-November 2025. EFSA J. 2025 Dec 18;23(12):e9834 (efsa.onlinelibrary.wiley.com/doi/epdf/10.2903/j.efsa.2025.9834).  

{5} United States Department of Agriculture (USDA). 2026. Highly Pathogenic Avian Influenza (HPAI) Detections in Wild Birds (www.aphis.usda.gov/livestock-poultry-disease/avian/avian-influenza/hpai-detections/wild-birds?page=1). 

{6} Canada Food Inspection Agency (CFIA). 2026. National Avian Influenza dashboard (cfiancr.maps.arcgis.com/apps/dashboards/89c779e98cdf492c899df23e1c38fdbc). 

{7} GISAID: EPI_ISL_20420880, EPI_ISL_20420879, EPI_ISL_20420878. 

{8} FAO. FAO alert on avian influenza – risk of upsurge and regional spread through wild birds in Latin America and the Caribbean, 8 April 2026 (https://openknowledge.fao.org/server/api/core/bitstreams/02a3ab2c-0f8d-427f-a71a-3f378a6474bd/content). 

{9} GISAID: EPI_ISL_19752381 and EPI_ISL_19823059–68. 

{10} Vanstreels R, Nelson MI, Artuso MC, Marchione VD, Piccini LE, Benedetti E, et al. Novel Highly Pathogenic Avian Influenza A(H5N1) Virus, Argentina, 2025. Emerg Infect Dis. 2025;31(12):2279-2283 (https://doi.org/10.3201/eid3112.250783).  

{11} Benedetti, E, Artuso, MC, Byrne, AMP, Garibotto, MDB, Avaro, M, Piccini, LE et al.  Emergence and Evolution of Triple Reassortant Highly Pathogenic Avian Influenza A(H5N1) Virus, Argentina, 2025. Preprint (https://doi.org/10.20944/preprints202512.0962.v1). 

{12} Rivetti AV Jr, Reischak D, Carnegie L, Otaka JNP, Domingues CS, Cardoso FG et al. Genomic diversity and reassortment of highly pathogenic avian influenza A/H5N1 virus (clade 2.3.4.4b) in Brazil: Evidence of multiple introductions and intra-epidemic reassortment in 2025. Virology. 2026 Feb;615:110751 (https://doi.org/10.1016/j.virol.2025.110751). 

{13} Steinfurth A, Lynton-Jenkins JG, Cleeland J, Mollett BC, Coombes HA, Moores A et al. Investigating high pathogenicity avian influenza virus incursions to remote islands: detection of H5N1 on Gough Island in the South Atlantic Ocean. Emerg Microbes Infect. 2026 Dec;15(1):2627076 (https://doi.org/10.1080/22221751.2026.2627076). 

{14} WOAH. World Animal Health Information System (WAHIS). Heard and McDonald Islands - Influenza A viruses of high pathogenicity (Inf. with) (non-poultry including wild birds) (2017-) - Immediate notification [FINAL] ( https://wahis.woah.org/#/inreview/7261?fromPage=event-dashboard-url). 

{15} WOAH. Sharing other important animal health information with WOAH (https://www.woah.org/en/what-we-do/animal-health-andwelfare/disease-data-collection/sharing-other-important-animal-health-information-with-woah/). 

{16} OFFLU. Beyond poultry: Rethinking monitoring and control of HPAI H5Nx anticipating spillover risks for mammals. 2026 (https://offlu.org/publications/beyond-poultry-rethinking-monitoring-and-control-of-hpai-h5nx-anticipating-spilloverrisks-for-mammals/). 

{17} Puryear W, Sawatzki K, Hill N, Foss A, Stone JJ, Doughty L, et al. Highly Pathogenic Avian Influenza A(H5N1) Virus Outbreak in New England Seals, United States. Emerg Infect Dis. 2023;29(4):786-791 (https://doi.org/10.3201/eid2904.221538). 

{18} Uhart MM, Vanstreels RET, Nelson MI, Olivera V, Campagna J, Zavattieri V et al. Epidemiological data of an influenza A/H5N1 outbreak in elephant seals in Argentina indicates mammal-to-mammal transmission. Nat Commun 15, 9516 (2024) (https://doi.org/10.1038/s41467024-53766-5). 

{19} OFFLU. Beyond poultry: Rethinking monitoring and control of HPAI H5Nx anticipating spillover risks for mammals. 2026 (https://offlu.org/publications/beyond-poultry-rethinking-monitoring-and-control-of-hpai-h5nx-anticipating-spilloverrisks-for-mammals/). 

{20} USDA. Highly Pathogenic Avian Influenza (HPAI) Detections in Livestock. 2026 (www.aphis.usda.gov/livestock-poultrydisease/avian/avian-influenza/hpai-detections/livestock). 

{21} USDA. Update: Genetic sequencing results for Wisconsin dairy herd detection of highly pathogenic avian influenza. 19 December 2025 (www.aphis.usda.gov/news/agency-announcements/update-genetic-sequencing-results-wisconsin-dairy-herd-detection-highly). 

{22} Rijksoverheid (Government of the Netherlands). Antibodies Against the Avian Influenza Virus Found in Dairy Cow. News, 23 January 2026 (www.rijksoverheid.nl/actueel/nieuws/2026/01/23/antistoffen-vogelgriepvirus-gevonden-bij-melkkoe). 

{23} GISAID. 

{24} US CDC. CDC A(H5N1) Bird Flu Response Update November 18, 2024 (www.cdc.gov/bird-flu/spotlights/h5n1-response-11152024.html). 

{25} US CDC. CDC Reports A(H5N1) Ferret Study Results. 7 June 2024 (www.cdc.gov/bird-flu/spotlights/ferret-study-results.html). 

{26} Pulit-Penaloza JA, Brock N, Belser JA, Sun X, Pappas C, Kieran TJ et al. Highly pathogenic avian influenza A(H5N1) virus of clade 2.3.4.4b isolated from a human case in Chile causes fatal disease and transmits between co-housed ferrets. Emerg Microbes Infect. 2024 Mar 17:2332667 (https://doi.org/10.1080/22221751.2024.2332667). 

{27} Eisfeld AJ, Biswas A, Guan L, Gu C, Maemura T, Trifkovic S et al. Pathogenicity and transmissibility of bovine H5N1 influenza virus. Nature (2024) (https://doi.org/10.1038/s41586-024-07766-6). 

{28} Restori KH, Septer KM, Field CJ, Patel DR, VanInsberghe D, Raghunathan V et al. Risk assessment of a highly pathogenic H5N1 influenza virus from mink. Nat Commun 15, 4112 (2024) (https://doi.org/10.1038/s41467-024-48475-y). 

{29} Pulit-Penaloza JA, Belser JA, Brock N, Kieran TJ, Sun X, Pappas C et al. Transmission of a human isolate of clade 2.3.4.4b A(H5N1) virus in ferrets. Nature. Published online October 28, 2024. (https://doi.org/10.1038/s41586-024-08246-7). 

{30} Gu C, Maemura T, Guan L, Eisfeld AJ, Biswas A, Kiso M et al. A human isolate of bovine H5N1 is transmissible and lethal in animal models. Nature (2024). (https://doi.org/10.1038/s41586-024-08254-7). 

{31} Brock N, Pulit-Penaloza JA, Belser JA, Pappas C, Sun X, Kieran TJ, et al. Avian Influenza A(H5N1) Isolated from Dairy Farm Worker, Michigan, USA. Emerg Infect Dis. 2025;31(6):1253-1256 (https://doi.org/10.3201/eid3106.250386). 

{32} US CDC. Influenza Risk Assessment Tool (IRAT) - Virus Report. Highly pathogenic avian influenza A(H5N1) virus; clade 2.3.4.4b Viruses: A/California/147/2024 and A/Washington/239/2024. Date of Evaluation: March 14, 2025 (www.cdc.gov/pandemicflu/media/pdfs/2025/IRATA-California-Washington.pdf). 

{33} Daulagala P, Cheng S, Chin A, Luk L, Leung K, Wu JT, et al. Avian Influenza A(H5N1) Neuraminidase Inhibition Antibodies in Healthy Adults after Exposure to Influenza A(H1N1)pdm09. Emerg Infect Dis. 2024;30(1):168-171 (https://doi.org/10.3201/eid3001.230756). 

{34} WHO. (2012). Rapid risk assessment of acute public health events (iris.who.int/handle/10665/70810). 

{35} Garg S, Reinhart K, Couture A, Kniss K, Davis CT, Kirby MK et al. Highly Pathogenic Avian Influenza A(H5N1) Virus Infections in Humans. N Engl J Med. 2025 Feb 27;392(9):843-854 (https://doi.org/10.1056/nejmoa2414610). 

{36} Pardo-Roa, C., Nelson, M.I., Ariyama, N. et al. Cross-species and mammal-to-mammal transmission of clade 2.3.4.4b highly pathogenic avian influenza A/H5N1 with PB2 adaptations. Nat Commun 16, 2232 (2025) (https://doi.org/10.1038/s41467-025-57338-z). 

{37} WHO. International Health Regulations (2005), as amended through resolutions WHA67.13 (2014), WHA75.12 (2022), and WHA77.17 (2024) (https://apps.who.int/gb/bd/pdf_files/IHR_2014-2022-2024-en.pdf). 

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{40} WOAH. Terrestrial Animal Health Code Chapter 10.4 Infection with high pathogenicity avian influenza viruses (https://www.woah.org/en/what-we-do/standards/codes-and-manuals/, cited on 05/05/2026). 

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Source: 

Link: https://www.who.int/publications/m/item/updated-joint-fao-who-woah-public-health-assessment-of-recent-high-pathogenicity-avian-influenza-a(h5)-virus-events-in-animals-and-people

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