Emergence of D1.1 #reassortant #H5N1 avian #influenza viruses in North #America

 

Abstract

Since 2021, highly pathogenic avian influenza viruses (HPAIVs) belonging to H5N1 clade 2.3.4.4b have circulated widely in North American wild birds and repeatedly spilled over into mammals. In 2025, the first H5N1-associated deaths in humans were recorded in the Western hemisphere, raising questions about how the ongoing evolution of the virus in wild birds impacts spillover risk. Here, our analysis of 21,471 H5N1 genomes identified an evolutionary shift in mid-2024, driven by interhemispheric migration from Asia and reassortment with new antigens. The genotypes that dominated the early years of North America's H5N1 epizootic traced their ancestry back to Europe, but Asia was the source of new "D1.1" genotype viruses that (a) spread faster, (b) have higher reassortment potential, (c) a broader host range, (d) repeatedly spill over to bovines, and (e) cause severe disease in humans, including non-farm workers.

Competing Interest Statement

The authors have declared no competing interest.

Funder Information Declared

Research Foundation - Flanders, https://ror.org/03qtxy027, G098321N, G0E1420N

European Union Horizon 2023 RIA project LEAPS, 101094685

DURABLE EU4Health project 02/2023-01/2027, 101102733

Fonds National de la Recherche Scientifique, F.4515.22

European Union Horizon 2020 project MOOD, 874850

Centers of Excellence for Influenza Research and Response, National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH), Department of Health and Human Services, 75N93021C00014

Source: 

Link: https://www.biorxiv.org/content/10.64898/2025.12.19.695329v2

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From #pandemic #influenza to novel #coronaviruses: emerging infectious diseases of the 21st century

 

Highlights

• Global mobility, climate pressures, and ecological change drive emerging infections.

• Highly pathogenic influenza strains, including H5N1, pose ongoing spillover risks and pandemic potential.

• SARS, MERS, and COVID-19 illustrate the pandemic potential of novel coronaviruses.

• Nipah, Ebola, Pteropine orthoreovirus and Zika remain high-impact threats for global health security.

• Mass gatherings can amplify transmission risks of emerging high-consequence viruses.

• Strengthened surveillance, diagnostics, and One Health strategies are essential for pandemic preparedness.

Abstract

Emerging infectious diseases have risen significantly in the twenty-first century as ecological disruption, climate change, expanding human–animal interfaces, and global mobility intensify opportunities for pathogen transmission. This review synthesizes historical and contemporary evidence across viral, bacterial, fungal, and parasitic threats to characterize how diverse pathogens emerge and spread. Foundational events such as the 1918 influenza pandemic, mid-century influenza pandemics, the emergence of HIV/AIDS, and the eradication of smallpox provide context for understanding modern disease dynamics. In recent decades, coronaviruses including SARS, MERS, and SARS-CoV-2, pandemic H1N1, avian influenza subtypes, and major arboviruses such as dengue, chikungunya, Zika, West Nile virus, and yellow fever have demonstrated the rapidity with which zoonotic pathogens can disseminate globally. Viral hemorrhagic fevers including Ebola, Marburg, Lassa, and Crimean–Congo hemorrhagic fever remain critical threats, especially in regions with limited health-care capacity. Concurrently, antimicrobial resistance, the emergence of Candida auris, and the climate-driven expansion of endemic mycoses involving Histoplasma, Coccidioides, and Blastomyces highlight the increasing importance of fungal pathogens. Parasitic diseases such as artemisinin-resistant malaria, zoonotic trypanosomiasis, and expanding Leishmania transmission reflect shifting ecological conditions. These patterns are shaped by intersecting drivers including deforestation, wildlife trade, agricultural intensification, urban crowding, conflict, and rapid microbial evolution that enable spillover and sustained transmission. Although advances in genomic surveillance, metagenomic diagnostics, mRNA vaccines, monoclonal antibodies, and broad-spectrum antivirals have strengthened global response capacity, substantial gaps persist in equity, surveillance, and access to countermeasures. Strengthening One Health systems and resilient public health infrastructures is essential to anticipate and mitigate emerging infectious threats.

Source: 

Link: https://www.sciencedirect.com/science/article/abs/pii/S0732889326000271?via%3Dihub

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#Concern for Highly Pathogenic Avian #Influenza #Spillover into #Cetaceans

 

Abstract

Influenza A virus (IAV) has a wide range of avian and mammalian hosts, leading to disease outbreaks and increasing the risk of panzootics and pandemics. Subtype H5N1 of clade 2.3.4.4b is causing the current high pathogenicity avian influenza (HPAI) panzootic. Environmental changes are fuelling the spread of HPAI H5N1 in wildlife worldwide, with occasional spillover events from seabirds to cetaceans. Sampling difficulties and limited tests available for diagnosis are a challenge to cetacean virology research. Understanding the risk of HPAI outbreaks in cetaceans requires a comprehensive examination of events of IAV infection. Documented cases relate to IAV subtypes H1N3, H13N2, H13N9, and H5N1 and have been reported in cetaceans sampled in the Pacific, Atlantic, and Arctic Oceans. The number of H5N1 IAV isolated from cetaceans is increasing and affects six host species of the families Delphinidae and Phocoenidae of the suborder Odontoceti. The analysis of 40 molecular markers of viral adaptation to mammals in 21 H5N1 cetacean isolates reveals mutations are present in three viral proteins: hemagglutinin (HA), polymerase basic protein 2 (PB2), and nucleoprotein (NP). Phylogenetic analysis of HA and PB2 sequences isolated from cetaceans and co-occurring cases in seabirds and marine mammals do not support sustained transmission of the virus between cetaceans. IAV H5N1 appears to be reaching cetaceans after spillover from seabirds and other marine mammals. Increasing worldwide surveillance of IAV infection of cetaceans is crucial, as these marine mammals are sentinel species for human pandemic preparedness and key species for marine biodiversity conservation and ecosystem health.

Source: 

Link: https://www.mdpi.com/1999-4915/17/12/1536

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Avian #influenza: First #global #dialogue targets the rising #pandemic #threat

 

09/09/2025 - Foz do Iguaçu, Brazil 

In an unprecedented response to the rapid global spread of high pathogenicity avian influenza (HPAI), stakeholders and experts from across the poultry sector, public health, science, and policy spheres have convened in Brazil in a landmark meeting. 

This first-ever global multisectoral dialogue aims to forge coordinated defense against the escalating threat to animal and human health and agricultural livelihoods.

Avian influenza, commonly known as bird flu, is a highly contagious viral disease that primarily infects birds. The virus belongs to the Type A influenza family, which is known for its ability to mutate and change rapidly.

Since 2020, HPAI has expanded rapidly across continents, devastating poultry flocks, impacting biodiversity, trade and food security, and raising concerns over its potential to spark a human pandemic. The currently circulating avian influenza panzootic is now widespread, and represents one of the most serious pandemic threats, experts warn. Avian influenza has spread to 83 mammal species including dairy cattle and wildlife, and poses a rapidly evolving risk.

“Avian influenza is no longer a sporadic threat; it’s becoming a global challenge,” said Beth Bechdol, FAO Deputy Director-General. “No single country or sector can tackle this threat in isolation—and failure is not an option. Practical, science-based collaboration like this is essential to protect our agrifood systems, livelihoods, and public health,” she added.

Organized by the Food and Agriculture Organization of the United Nations (FAO) in partnership with the Brazilian Ministry of Agriculture and Livestock, the event “Tackling high pathogenicity avian influenza together - Global science, policy and private sector dialogue” brings together around 500 experts and decision-makers to galvanize multisectoral collaboration and investment. Representatives from the private sector, including industry associations involved in the production of poultry and the provision of animal health services are also joining government and scientific leaders for the first time in this type of global dialogue—providing an opportunity to better understand private sector’s challenges, recognize its ongoing efforts, and highlight the solutions it is already implementing to tackle the threat posed by avian influenza.

Experts from Asia, Africa, Europe, and the Americas – many of whom are members of FAO and World Organization for Animal Health (WOAH) OFFLU Network of Expertise on Animal Influenza – are also participating in the dialogue.

“Addressing avian influenza requires a collective effort that unites countries, productive sectors, the scientific community, and international organizations. This challenge must be met with full transparency, as only in this way can we build trust and safeguard global food security,” said Carlos Favaro, Brazil’s Minister of Agriculture and Livestock. “I would like to emphasize that this year, when avian influenza was detected on a commercial farm, Brazil demonstrated a decisive difference. Our swift and effective response highlighted the strength and credibility of Brazil’s sanitary system.”

Priority themes

The event seeks to build on the Global Strategy for the Prevention and Control of HPAI, recently launched by FAO in collaboration with WOAH. This strategy aims to support the development and implementation of national and regional action plans while strengthening global efforts to reduce transboundary and pandemic risks.

The three-day event focuses on:

-- Identifying effective HPAI prevention and control strategies—particularly in low-income countries and informal backyard poultry systems.

-- Promoting early warning systems, vaccination strategies, and biosecurity measures.

-- Enhancing multisectoral coordination based on the One Health approach.

-- Sharing innovative, field-ready solutions for diagnostics, surveillance, and outbreak response.

Thanawat Tiensin, Chief Veterinarian of FAO and Director of the Animal Production and Health Division summarized FAO’s approach in his remarks: “Improved surveillance, biosecurity, and vaccination when appropriate, combined with rapid disease control are keys to controlling this disease. At the same time, the sustainable transformation of poultry production offers new approaches and safeguards to prevent losses from poultry diseases. It will take a holistic approach and partnering with the private sector to effectively reduce the risk of avian influenza for generations to come.”

“The debate around Avian Influenza is a matter of international cooperation and requires joint efforts from all nations,” said Ricardo Santin, president of the Brazilian Association of Animal Protein and of the International Poultry Council. “It is an issue with a direct impact on trade flows and, consequently, on inflation and on global food security. These are sensitive matters that must be guided by knowledge and science, and that call for a revision of concepts and paradigms.”

(...)

Source: Food and Agriculture Organization of the UN, https://www.fao.org/newsroom/detail/avian-influenza--first-global-dialogue-targets-the-rising-pandemic-threat/en

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Genetic #reassortment and diversification of #host specificity have driven evolutionary trajectories of #lineages of #panzootic #H5N1 #influenza

 

Abstract

Since 2021, subclade 2.3.4.4b A(H5N1) high pathogenicity avian influenza (HPAI) viruses have undergone changes in ecology and epidemiology, causing a panzootic of unprecedented scale in wild and domestic birds with spill-over infections and perceptible transmission in a range of mammalian species, raising concern over zoonotic potential. HPAI viruses readily exchange gene segments with low pathogenicity avian influenza viruses via reassortment, a mechanism that facilitates pronounced phenotypic change. Observations suggest changes in the seasonality and host range of panzootic viruses, however, data on the role of reassortment in determining such features are limited. Using phylodynamic approaches, we describe the emergence of the panzootic lineage and using a novel global genotype classification system we describe the subsequent emergence and global structuring of genotypes generated by reassortment. Focusing on evolutionary dynamics in Europe, we show reassortment has produced high fitness genotypes with enhanced capacity for transmission and further we show such advantages can be host-dependent, contrasting successful generalist genotypes with a specialist lineage (EA-2022-BB) adapted to birds of the order Charadriiformes. Experimental investigation of NS1-mediated shutoff indicates this Charadriiformes-specialist does not inhibit host cellular gene expression and hamper the defences of more typical hosts such as water- and land-fowl. We attribute this primarily to variation at position 127 of the NS1 protein. Our results emphasise that reassortment has driven phenotypic change, affected viral fitness, and caused diversification of host specificity and seasonality. Such factors should be considered in studies that seek to identify drivers of HPAI spread and map spillover risk. Additionally, relaxation of host specialisation, ecological diversification, and potential endemicity in atypical host populations present new reassortment opportunities that could result in further novel phenotypes.

Competing Interest Statement

The authors have declared no competing interest.

Funder Information Declared

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

BBSRC Institute Strategic Grant, BBS/E/RL/230002C, BBS/E/RL/230002D, BBS/E/PI/230002A, BBS/E/PI/230002B

Medical Research Council, MR/Y03368X/1

European Union, https://ror.org/019w4f821, 874735

Department for Environment Food and Rural Affairs, https://ror.org/00tnppw48, SE2223, SE2230, SV3400, SV3032, SV3006

Source: BioRxIV, https://www.biorxiv.org/content/10.1101/2025.08.20.670882v1

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The Winners Take It All? 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 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 unknown. 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 in 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 3% seeded large clusters of secondary reassortants soon after their own emergence. Statistical modelling revealed that reassortant success was strongly shaped by ecological factors, including circulation in specific wild bird orders and the ability to infect a wider range of host niches. Reassortant dispersal was linked to poultry trade intensity, particularly in North America. Collectively, our findings reveal reassortment dynamics in H5 HPAIVs and identify key virological and ecological drivers underpinning the emergence and global 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/Y03368X/1

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

National Key Research and Development Program of China, 2023YFC2307500

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

Fonds National de la Recherche Scientifique, F.4515.22

Fonds voor Wetenschappelijk Onderzoek - Vlaanderen, G098321N

Source: BioRxIV, https://www.biorxiv.org/content/10.1101/2025.07.19.665680v1

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Counting Cases, Conserving #Species: Addressing Highly Pathogenic Avian #Influenza in #Wildlife

Abstract

Highly pathogenic avian influenza (HPAI) has become a critical threat to wildlife, shifting from a seasonal epizootic to a persistent, year-round panzootic with global consequences. Here, we summarize the origin, evolutionary mechanisms, and expanding host range of the current H5N1 virus (clade 2.3.4.4b) and assess its impact on wildlife. Over the past five years, HPAI has caused the deaths of millions of wild birds, causing dramatic population declines in several seabird species. However, comprehensive quantitative mortality data remain scarce, as existing records are often anecdotal, focus on localized mass die-offs, and thus represent only a fraction of the true magnitude of mortality. This gap in data limits the ability to predict outbreak dynamics and mitigate long-term consequences. Using the Northwestern European Sandwich Tern (Thalasseus sandvicensis) population as a case study, we demonstrate the value of integrating mortality data with ecological, serological and genetic data before, during and after an outbreak. This approach uncovered age-specific vulnerability, selective mortality, and population immunological responses. In addition, insights gained with respect to the role of breeding density, carcass removal, and host adaptation in modulating outbreak dynamics are likely to be generalizable across seabird species. The absence of a centralized and standardized wildlife mortality monitoring framework, on the other hand, remains a major barrier to effective outbreak forecasting and conservation planning. We argue that integrating field-based mortality data, population monitoring, serological assays, and genetic analyses within a One Health framework is essential to enable early detection, targeted mitigation, and robust evaluation of outbreak impacts. Without a proactive and data-driven approach to conservation, HPAI will continue to threaten global wildlife populations, with cascading ecological, economic and public health consequences.

Source: BioRxIV, https://www.biorxiv.org/content/10.1101/2025.06.18.660293v1

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Global #risk #mapping of highly pathogenic avian #influenza #H5N1 and H5Nx in the light of epidemic episodes occurring from 2020 onward

Abstract

Avian influenza (AI) is a highly contagious viral disease affecting poultry and wild water birds, posing significant global challenges due to its high mortality rates and economic impacts. Highly pathogenic avian influenza (HPAI) outbreaks, particularly those caused by H5N1 and its variants, have surged since their first occurrence in 1959. The HPAI H5N1 clade 2.3.4.4b viruses have notably expanded its geographical reach, affecting numerous countries, diverse avian species, and now wild and domestic mammals. Using an ecological niche modelling approach, this study aims to elucidate the environmental factors associated with the increased HPAI H5 cases since 2020, investigate potential shifts in ecological niches, and predict new areas suitable for local viral circulation. Focusing on H5N1 and H5Nx strains, we have developed ecological niche models for HPAI case in both wild and domestic birds while considering two distinct periods: 2015-2020 and 2020-2022. Key environmental predictors include chicken and duck population density, human density, distance to water bodies, and several land cover variables. Post-2020, we observe a notable increase in the relative importance of some of these predictors, such as intensive chicken population density and cultivated vegetation. The resulting risk maps reveal notable ecological suitability for local HPAI H5 circulation in Europe, Asia, as well as North and South America, with notable expansions of the areas at risk post-2020. The spatial distribution of HPAI H5 occurrences in wild birds appears to be primarily influenced by urban areas and open water regions. Overall, global risk maps derived from our models identify regions at risk where surveillance and control measures should be prioritised. Finally, our analyses also highlight a shift in the diversity of species affected by HPAI outbreaks, with a higher variety of avian species, particularly sea birds, being impacted post-2020. This increased diversity suggests that ecological shifts in HPAI H5 circulation may be accompanied by a broader range of susceptible species. Overall, these results further contribute to the understanding of HPAI epidemiology.

Source: BioRxIV, https://www.biorxiv.org/content/10.1101/2024.11.15.623755v2

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#Evolution, spread and #impact of highly pathogenic #H5 avian #influenza A viruses

Abstract

Since their first detection in 1996, highly pathogenic avian influenza viruses with H5 haemagglutinin of the A/Goose/Guangdong/1/1996 (Gs/Gd) lineage have caused outbreaks in domestic and wild animals associated with mass morbidity and mortality, and economic losses as well as sporadic human infections. These viruses have spread to hosts across the European, Asian, African, and North and South American continents, and most recently Antarctica, representing a major threat to wildlife, domestic animals and humans. Owing to continuous circulation in poultry, Gs/Gd lineage viruses have diversified into numerous distinct genetic and antigenic (sub)clades, and genetic diversity has further increased by extensive reassortment with low pathogenic avian influenza viruses of wild birds. In this Review, we discuss the historical emergence of Gs/Gd lineage viruses and their evolution and geographical spread. An overview of the major determinants of host range and cross-species transmission is provided to summarize phenotypic changes that may signal increased zoonotic or pandemic risks. The recent unusual outbreaks in wild carnivorous mammals and dairy cows is discussed, as well as the changing risk to humans. Countermeasures and mitigation strategies are described from the One Health perspective for future (pre-)pandemic preparedness.

Source: Nature Reviews Microbiology, https://www.nature.com/articles/s41579-025-01189-4

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Highly pathogenic avian #influenza #H5N1: #history, current #situation, and #outlook

ABSTRACT

The H5N1 avian panzootic has resulted in cross-species transmission to birds and mammals, causing outbreaks in wildlife, poultry, and US dairy cattle with a range of host-dependent pathogenic outcomes. Although no human-to-human transmission has been observed, the rising number of zoonotic human cases creates opportunities for adaptive mutation or reassortment. This Gem explores the history, evolution, virology, and epidemiology of clade 2.3.4.4b H5N1 relative to its pandemic potential. Pandemic risk reduction measures are urgently required.

Source: Journal of Virology, https://journals.asm.org/doi/full/10.1128/jvi.02209-24?af=R

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Analyses of #phylogenetics, natural #selection, and #protein structure of clade 2.3.4.4b #H5N1 #Influenza A reveal that recent viral lineages have evolved promiscuity ...

Abstract

H5N1 influenza has been circulating in birds from Eurasia and Africa for more than 146 years, but human infection has been sporadic. H5N1 (clade 2.3.4.4b) has recently infected hundreds of species of wild and domestic birds and mammals in North America. Furthermore, as of February 26, 2025, H5N1 has infected 70 humans in the United States, and one infection proved lethal. Furthermore, in attempts to control H5N1 in the United States, 10s of millions of egg-laying chickens have died or been culled. These efforts have led to very high egg prices in the United States. We have developed an analytical bioinformatics and genomics workflow to understand better how H5N1 is circulating in North America and adapting to new host species. Our workflow consists of: 1) Phylogenetic analyses of large viral sequence datasets to identify subclades of viral lineages causing the current outbreaks in humans and farm animals and closely related viral background lineages. 2) Next, we transfer sequence data from subclades of interest with farm animal and human infection, background data, and vaccine candidate data to analyses of natural selection. 3) Once we identify mutations of interest that underlie recent viral adaptation to animal and human infection, we perform computational structural analyses of binding to host proteins for cell receptors and immune processes. Here, we show that H5N1 (clade 2.3.4.4b) is spreading in North America as two distinct subclades of interest for human and animal health. These viral lineages have achieved a vast host range by efficiently binding the viral surface protein Hemagglutinin (HA) to both mammalian and avian receptors. This novel promiscuity of host range is concomitant with the additional strengthening of the polymerase basic 2 (PB2) viral protein's binding for mammalian and avian immune proteins. Once bound, the immune proteins are disabled, thus allowing for more efficient replication of H5N1 in mammalian and avian cells than seen in the recent past. In conclusion, H5N1 (clade 2.3.4.4b) is causing an animal pandemic through promiscuity of host rage and strengthening ability to evade the innate immune systems of both mammalian and avian cells.

Source: BioRxIV, https://www.biorxiv.org/content/10.1101/2025.03.15.641219v1?rss=1

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#USA confirms its first severe case of #H5N1 #flu - #California declares state of #emergency - #UN agencies warn: This epidemic "is increasingly crossing species barriers"

According to CCTV News, on December 18 local time, California Governor Gavin Newsom declared a state of emergency in California to deal with the increasingly serious avian influenza epidemic.

Although there have been no cases of human-to-human transmission in California, 61 people have been infected with avian influenza in the United States, 34 of which are from California. Newsom emphasized that although the risk is low, the government will continue to take necessary measures to prevent the spread of the virus and open funds to support the emergency response of relevant agencies.

According to Xinhua News Agency, the U.S. Centers for Disease Control and Prevention issued a statement on the 18th saying that the United States reported the first severe case of human infection with the H5N1 avian influenza virus . The patient was hospitalized and his infection may be related to contact with sick and dead poultry raised in private backyard farms.

The CDC said in a statement that the patient was from Louisiana, and was diagnosed with the H5N1 avian influenza virus on the 13th. The investigation into the source of infection is still ongoing, but it can be confirmed that the patient had contact with sick and dead poultry raised in a private backyard farm. This is also the first case of human infection with the H5N1 avian influenza virus in the United States related to a private backyard farm.

Preliminary genetic analysis results show that the avian influenza virus that infected the patient belongs to the D1.1 type. The CDC is conducting further genome sequencing on the virus samples.

According to the data from the US Centers for Disease Control and Prevention, since April this year, a total of 61 cases of human infection with the H5 avian influenza virus have been reported in the United States. The agency said that it is not surprising that some people have been seriously ill with the H5N1 avian influenza. Previously, other countries have reported cases of severe illness or death from human infection with the H5N1 avian influenza. So far, no human-to-human transmission of the H5 avian influenza virus has been found. The direct risk to public health posed by the H5N1 avian influenza is still low.

The CDC reminds the public to avoid contact with sick or dead animals, especially wild birds and poultry, as much as possible. Individuals who have direct or close contact with wild birds or sick, dead poultry and other animals need to wear protective equipment.

According to a report by Xinhua News Agency on November 7, a new study conducted by researchers from the US Centers for Disease Control and Prevention and other institutions showed that the actual number of US dairy farm workers infected with the highly pathogenic H5N1 avian influenza virus may far exceed official statistics. The relevant research report was published in the US Centers for Disease Control and Prevention's Morbidity and Mortality Weekly Journal.

From June to August 2024, researchers collected and tested blood samples from workers on dairy farms in Michigan and Colorado, where outbreaks of highly pathogenic H5N1 avian influenza had occurred. They found that 8 of the 115 workers tested had recently been infected with the H5N1 avian influenza virus, with an infection rate of 7%.

Caitlin Rivers, an epidemiologist at the Johns Hopkins Center for Health Security in the United States, said that thousands of dairy workers may have been exposed to infected dairy cows, and the new study shows that many cases have been missed. She believes that it is likely that most or all states with H5N1 avian influenza outbreaks have human cases.

Since March this year, the H5N1 avian influenza virus has continued to spread in the United States. According to the latest statistics from the U.S. Department of Agriculture, the H5N1 avian influenza virus has been detected in more than 440 dairy cow herds in 15 states in the United States.

In response to the latest findings, the CDC is expanding testing of affected dairy farm workers. The agency is also recommending that workers who have had high-risk contact with infected animals take antiviral drugs.

According to Cankaoxiaoxi.com, Reuters reported on October 31 that bird flu has spread rapidly among poultry in many EU countries this season, raising concerns about a repeat of the crisis. Previous bird flu outbreaks have killed tens of millions of poultry in many EU countries, and people are also worried that bird flu could be transmitted to humans.

The UK Department for Environment, Food and Rural Affairs announced on December 17 that cases of highly pathogenic avian influenza were confirmed in two breeding farms in Norfolk. The animal health department decided to kill the poultry in the farms and designate protection and monitoring areas.

The Food and Agriculture Organization of the United Nations (FAO), the World Organization for Animal Health and other organizations warned at a briefing at the United Nations Office in Geneva on the 17th that the avian influenza epidemic sweeping the world "is increasingly crossing species barriers . "

Gregorio Torres, director of the Scientific Department of the World Organization for Animal Health, said that since October 2021, the avian influenza epidemic has killed more than 300 million poultry worldwide. The virus is increasingly crossing species barriers, infecting poultry and wild mammals, causing serious impacts on the ecosystem.

FAO official Madhur Dingra also pointed out that the impact of the highly pathogenic avian influenza virus has spread to wild animals, infecting more than 500 species of birds and more than 70 species of mammals, including endangered animals such as polar bears.

Source: SINA, https://news.sina.com.cn/w/2024-12-19/doc-inczynpw0156337.shtml

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Avian #flu reported in 108 countries across five #continents, says #UN health agency

In an update on the mutating virus - known as H5N1 – Dr. Madhur Dhingra from the Food and Agriculture Organization, FAO, said that it had “spilled over into wildlife”. 

More than 500 bird species have been infected along with at least 70 mammalian species, including the endangered California condor and polar bears. 

In regions that are heavily reliant on poultry as a primary source of protein, the FAO medic insisted that avian influenza “poses a serious threat to food and nutrition security”.

Economic damage

Dr Dhingra warned that hundreds of millions of people’s livelihoods have been affected by the virus – an economic burden on farmers that could prevent them from investing in adequate biosafety measures.

Following the emergence of H5N1 influenza virus in dairy cattle, the WHO has joined calls for strengthened surveillance and biosecurity on farms, to keep animals and people safe.

The UN health agency said that in 2024, 76 people have been infected with the H5 avian influenza strain, and most were farm workers. More than 60 cases originated in the US, which has also reported outbreaks of H5 in wildlife and poultry and, more recently, in dairy cattle.

There have also been cases reported in Australia, Canada, China, Cambodia and Viet Nam.

Low risk to humans – for now

Dr. Maria Van Kerkhove, who currently serves as Director of Epidemic and Pandemic Threat Management for the WHO, said that based on the latest science, “we assess the risk of infection for the public – you and I – is currently low.”

But if you work on a farm, she cautioned – and are exposed to infected animals – “we assess the current public health risk to be low-to-moderate,” depending on the level of personal protection taken.

There is no evidence so far that the H5N1 viruses have adapted to spread between people and there has been no reported cases of human-to-human transmission.

No room for complacency

“We must remember, however, that this can change quickly,” the UN pandemic expert added, “as the virus is evolving and we must be prepared for such a scenario.”

Every case that occurs in humans must therefore be investigated thoroughly.

Dr. Van Kerkhove also stressed the importance of drinking pasturised milk – and if that’s not available, of heating milk before consumption.

“We want to reiterate the critical importance of using a One Health approach across sectors – globally, nationally, and sub-nationally -  to tackle avian influenza effectively, to minimize the risk in animals and humans,” she concluded.  

Source: United Nations, https://news.un.org/en/story/2024/12/1158286 

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