{Excerpt}
(...)
Time Period: May 24, 2026 - May 30, 2026
-- A(H5) Detection: 6 site(s) (1.4%)
-- No Detection: 421 site(s) (98.6%)
-- No samples: 69 site(s)
(...)
Source:
Link: https://www.cdc.gov/wastewater/emerging-viruses/h5.html?
____
I am an Italian blogger, active since 2005 with main focus on emerging infectious diseases such as avian influenza, SARS, antibiotics resistance, and many other global Health issues. Other fields of interest are: climate change, global warming, geological and biological sciences. My activity consists mainly in collection and analysis of news, public services updates, confronting sources and making decision about what are the 'signals' of an impending crisis (an outbreak, for example). When a signal is detected, I follow traces during the entire course of an event. I started in 2005 my blog ''A TIME'S MEMORY'', now with more than 40,000 posts and 3 millions of web interactions. Subsequently I added an Italian Language blog, then discontinued because of very low traffic and interest. I contributed for seven years to a public forum (FluTrackers.com) in the midst of the Ebola epidemic in West Africa in 2014, I left the site to continue alone my data tracking job.
New human cases{2}:
° From 1 April to 8 May 2026, based on reporting date, detections of influenza A(H5N1) in three humans, influenza A(H5N6) in one human, influenza A(H9N2) in five humans, and influenza A(H1N2) variant ((H1N2)v) virus in one human were reported officially.
Circulation of influenza viruses with zoonotic potential in animals:
° High pathogenicity avian influenza (HPAI) events in poultry and non-poultry animal species continue to be reported to the World Organisation for Animal Health (WOAH).{3}
° The Food and Agriculture Organization of the United Nations (FAO) also provides a global update on avian influenza viruses with pandemic potential.{4}
° Additionally, low pathogenicity avian influenza viruses as well as swine influenza viruses continue to circulate in animal populations.
Risk assessment{5}:
° Sustained human to human transmission has not been reported associated with the above-mentioned human infection events.
° Based on information available at the time of this risk assessment update, the overall public health risk from currently known influenza A viruses detected at the human-animal interface has not changed and remains low.
° At present, these viruses are not thought to be capable of sustained human-to-human transmission, although this could change as they evolve.
° Although human infections with viruses of animal origin are infrequent, they are not unexpected at the human-animal interface.
IHR compliance{6}:
° This includes any influenza A virus that has demonstrated the capacity to infect a human and its haemagglutinin (HA) gene (or protein) is not a mutated form of those, i.e. A(H1) or A(H3), circulating widely in the human population.
° Information from these notifications is critical to inform risk assessments for influenza at the human-animal interface.
Avian influenza viruses in humans A(H5N1), Bangladesh
° On 23 April 2026, Bangladesh notified WHO of one laboratory-confirmed human case of avian influenza A(H5) infection in a child from Sylhet Division.
° The patient developed fever and cough on 27 March 2026 and was admitted to hospital on 28 March with a clinical diagnosis of measles with bronchopneumonia.
° As part of hospital-based influenza surveillance, a sample was collected on 29 March and received by the Institute of Epidemiology, Disease Control and Research (IEDCR) on 20 April.
° The sample tested positive for influenza A(H5N1) on the same day by real-time reverse transcription polymerase chain reaction (RT-PCR).
° The patient was discharged on 30 March.
° No additional cases were reported among identified contacts.
° Epidemiological investigations identified exposure to household poultry.
° This is the second laboratory-confirmed human case of avian influenza A(H5N1) reported in Bangladesh in 2026.
A(H5N1), Cambodia
° On 22 April 2026, Cambodia notified WHO of one laboratory-confirmed human case of avian influenza A(H5) infection in a 66-year-old woman with comorbidities from Svay Rieng province.
° The patient developed symptoms on 15 April 2026 and was admitted to district hospital on 16 April and provincial hospital the next day.
° As part of severe acute respiratory infection surveillance, a sample was collected on 17 April and received by the National Institute of Public Health on 21 April.
° The sample tested positive for influenza A(H5N1) on the same day by real-time RT-PCR, and the result was confirmed by Institut Pasteur du Cambodge on 22 April.
° The patient died on 22 April.
° No additional cases were reported among 15 identified contacts.
° Epidemiological investigations identified exposure to sick and dead household chickens prior to illness onset.
° Four human infections with A(H5N1) viruses have been confirmed in Cambodia in 2026, including one fatal case.
° Influenza A(H5N1) viruses continue to be detected in domestic birds in Cambodia in 2026, including in areas where human cases have been detected.
° Where the information is available, the genetic sequence data from the viruses from the human cases closely matches that from recent local animal viruses and are identified as clade 2.3.2.1e viruses.
° From the information available thus far on these recent human cases, there is no indication of human-to-human transmission of the A(H5N1) viruses.
A(H5N1), India
° On 27 March 2026, India notified WHO of one laboratory-confirmed human case of avian influenza A(H5N1) infection in a child from West Bengal state.
° The patient developed fever and cough and was admitted to hospital on 19 March.
° The patient was discharged on 23 March.
° Laboratory testing at the Indian Council of Medical Research (ICMR) National Institute of Virology in Pune confirmed influenza A(H5N1).
° Genomic sequencing identified the virus as belonging to clade 2.3.2.1a, closely related to strains previously reported from Bangladesh and India in 2025.
° No additional cases were reported among identified contacts.
° Epidemiological investigations identified likely indirect exposure to poultry.
° This is the first laboratory-confirmed human case of avian influenza A(H5N1) reported in India in 2026.
A(H5N6), China
° On 29 April 2026, China notified WHO of one laboratory-confirmed human case of avian influenza A(H5N6) infection in a 55-year-old female with comorbidities from Chongqing Municipality.
° She had onset of symptoms on 16 April 2026 and was hospitalized on 23 April with severe pneumonia.
° The patient died on 3 May 2026.
° She had slaughtered and prepared poultry prior to onset of symptoms.
° Environmental samples collected from the food preparation tools at the patient’s residence tested positive for influenza A(H5).
° No further cases were detected among contacts of the patient.
° This is the first laboratory-confirmed human case of infection with an A(H5N6) virus detected since 2024.
According to reports received by WOAH, various influenza A(H5) subtypes continue to be detected in wild and domestic birds in Africa, the Americas, Asia and Europe.
Infections in non-human mammals are also reported, including in marine and land mammals.{7}
A list of bird and mammalian species affected by HPAI A(H5) viruses is maintained by FAO.{8}
Risk assessment for avian influenza A(H5) viruses:
1. What is the current global public health risk of additional human cases of infection with avian influenza A(H5) viruses?
° Most human infections so far have been reported in people exposed to A(H5) viruses, for example, through contact with infected poultry or contaminated environments, including live poultry markets, and occasionally infected mammals and contaminated environments.
° As long as the viruses continue to be detected in animals and related environments humans are exposed to, further human cases associated with such exposures are expected but remain unusual.
° The impact for public health if additional sporadic cases are detected is minimal.
° The current overall global public health risk is low.
2. What is the likelihood of sustained human-to-human transmission of avian influenza A(H5) viruses related to the events above?
° No sustained human-to-human transmission has been identified associated with the recent reported human infections with avian influenza A(H5) viruses.
° There has been no reported human-to-human transmission of A(H5N1) viruses since 2007, although there may be gaps in investigations.
° In 2007 and the years prior, small clusters of A(H5) virus infections in humans were reported, including some involving health care workers, where limited human-to-human transmission could not be excluded; however, sustained human-to-human transmission was not reported.
° Current evidence suggests that influenza A(H5) viruses related to these events did not acquire the ability to efficiently transmit between people.
3. What is the likelihood of international spread of avian influenza A(H5) viruses by travellers?
° Should infected individuals from affected areas travel internationally, their infection may be detected in another country during travel or after arrival.
° If this were to occur, further communitylevel spread is considered unlikely as current evidence suggests these viruses have not acquired the ability to transmit easily among humans.
A(H9N2), China
° Between 7 April and 6 May 2026, China notified WHO of five laboratory-confirmed cases of A(H9N2) virus infection.
° The first case had comorbidities and developed severe pneumonia.
° All the cases except the child from Jiangxi had exposure to live bird markets or household birds.
° Samples from environments associated with the likely area of exposure of some of these cases tested positive for A(H9) viruses.
° No further cases were detected among contacts of these cases.
Risk assessment for avian influenza A(H9N2):
1. What is the global public health risk of additional human cases of infection with avian influenza A(H9N2) viruses?
° Most human cases follow exposure to the A(H9N2) virus through contact with infected poultry or contaminated environments.
° Most human infections of A(H9N2) to date have resulted in mild clinical illness.
° Since the virus is endemic in poultry in multiple countries in Africa and Asia, additional human cases associated with exposure to infected poultry or contaminated environments are expected but remain unusual.
° The impact to public health if additional sporadic cases are detected is minimal.
° The overall global public health risk is low.
2. What is the likelihood of sustained human-to-human transmission of avian influenza A(H9N2) viruses related to these events?
° At the present time, no sustained human-to-human transmission has been identified associated with the recently reported human infections with A(H9N2) viruses.
° Current evidence suggests that A(H9N2) viruses from these cases did not acquire the ability of sustained transmission among humans.
3. What is the likelihood of international spread of avian influenza A(H9N2) virus by travellers?
° Should infected individuals from affected areas travel internationally, their infection may be detected in another country during travel or after arrival.
° If this were to occur, further community level spread is considered unlikely as current evidence suggests the A(H9N2) virus subtype has not acquired the ability to transmit easily among humans.
Swine influenza viruses in humans
Influenza A(H1N2)v, United States
° On 2 May 2026, the United States notified WHO of a laboratory-confirmed case of A(H1N2)v influenza virus infection in an individual under 18 years of age from Nebraska.
° The patient had onset of mild illness in early April 2026 and has recovered.
° A respiratory specimen collected in mid-April as part of routine surveillance was sent to the US Centers for Disease Control and Prevention (CDC).
° Real-time RT-PCR testing by CDC determined the sample was positive for an influenza A(H1N2)v virus.
° Additional genetic and virologic characterization is currently underway.
° Local public health investigations did not identify direct or indirect exposure to swine.
° One household contact had mild respiratory illness also in early April but no additional cases of A(H1N2)v were identified at the time of reporting.{9}
° This is the first human A(H1N2)v infection detected in the United States in 2026.
Risk assessment for swine influenza viruses:
1. What is the public health risk of additional human cases of infection with swine influenza viruses?
° Swine influenza viruses circulate in swine populations in many regions of the world.
° Depending on geographic location, the genetic characteristics of these viruses differ.
° Most human cases are exposed to swine influenza viruses through contact with infected animals or contaminated environments.
° Human infection tends to result in mild clinical illness in most cases.
° Since these viruses continue to be detected in swine populations, further human cases are expected.
° The impact to public health if additional sporadic cases are detected is minimal.
° The overall risk of additional sporadic human cases is low.
2. What is the likelihood of sustained human-to-human transmission of swine influenza viruses?
° No sustained human-to-human transmission was identified associated with the event described above.
° Current evidence suggests that contemporary swine influenza viruses have not acquired the ability of sustained transmission among humans.
3. What is the likelihood of international spread of swine influenza viruses by travellers?
° Should infected individuals from affected areas travel internationally, their infection may be detected in another country during travel or after arrival.
° If this were to occur, further community level spread is considered unlikely as current evidence suggests that these viruses have not acquired the ability to transmit easily among humans.
Overall risk management recommendations:
° Surveillance and investigations
• Due to the constantly evolving nature of influenza viruses, WHO continues to stress the importance of global strategic surveillance in animals and humans to detect virologic, epidemiologic and clinical changes associated with circulating influenza viruses that may affect human (or animal) health. Continued vigilance is needed within affected and neighbouring areas to detect infections in animals and humans. Close collaboration with the animal health and environment sectors is essential to understand the extent of the risk of human exposure and to prevent and control the spread of animal influenza. WHO has published guidance on surveillance for human infections with avian influenza A(H5) viruses.
• As the extent of influenza virus circulation in animals is not clear, epidemiologic and virologic surveillance and the follow-up of suspected human cases should continue systematically. Guidance on investigation of non-seasonal influenza and other emerging acute respiratory diseases has been published on the WHO website.
• Countries should increase avian influenza surveillance in domestic and wild birds, enhance surveillance for early detection in cattle populations in countries where HPAI is known to be circulating, include HPAI as a differential diagnosis in non-avian species, including cattle and other livestock populations, with high risk of exposure to HPAI viruses; monitor and investigate cases in non-avian species, including livestock, report cases of HPAI in all animal species, including unusual hosts, to WOAH and other international organizations, share genetic sequences of avian influenza viruses in publicly available databases, implement preventive and early response measures to break the HPAI transmission cycle among animals through movement restrictions of infected livestock holdings and strict biosecurity measures in all holdings, employ good production and hygiene practices when handing animal products, and protect persons in contact with suspected/infected animals.{10} More guidance can be found from WOAH and FAO.
• When there has been human exposure to a known outbreak of an influenza A virus in domestic poultry, wild birds or other animals – or when there has been an identified human case of infection with such a virus – enhanced surveillance in potentially exposed human populations becomes necessary. Enhanced surveillance should consider the health care seeking behaviour of the population, and could include a range of active and passive health care and/or communitybased approaches, including: enhanced surveillance in local influenza-like illness (ILI)/SARI systems, active screening in hospitals and of groups that may be at higher occupational risk of exposure, and inclusion of other sources such as traditional healers, private practitioners and private diagnostic laboratories.
• Vigilance for the emergence of novel influenza viruses with pandemic potential should be maintained at all times including during a non-influenza emergency. In the context of the cocirculation of SARS-CoV-2 and influenza viruses, WHO has updated and published practical guidance for integrated surveillance.
° Notifying WHO
• All human infections caused by a new subtype of influenza virus are notifiable under the International Health Regulations (IHR, 2005).{11,12} State Parties to the IHR (2005) are required to immediately notify WHO of any laboratory-confirmed{13} case of a recent human infection caused by an influenza A virus with the potential to cause a pandemic{14}. Evidence of illness is not required for this report. Evidence of illness is not required for this report.
• WHO published the case definition for human infections with avian influenza A(H5) virus requiring notification under IHR (2005): https://www.who.int/teams/global-influenzaprogramme/avian-influenza/case-definitions.
° Virus sharing and risk assessment
• It is critical that these influenza viruses from animals or from humans are fully characterized in appropriate animal or human health influenza reference laboratories. Under WHO’s Pandemic Influenza Preparedness (PIP) Framework, Member States are expected to share influenza viruses with pandemic potential on a timely basis{15} with a WHO Collaborating Centre for influenza of GISRS. The viruses are used by the public health laboratories to assess the risk of pandemic influenza and to develop candidate vaccine viruses.
• 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 risk elements. The results of TIPRA complement those of the risk assessment provided here, and those of prior TIPRA risk assessments are published at http://www.who.int/teams/global-influenza-programme/avianinfluenza/tool-for-influenza-pandemic-risk-assessment-(tipra). Risk reduction
• Given the observed extent and frequency of avian influenza in poultry, wild birds and some wild and domestic mammals, the public should avoid contact with animals that are sick or dead from unknown causes, including wild animals, and should report dead birds and mammals or request their removal by contacting local wildlife or veterinary authorities. Eggs, poultry meat and other poultry food products should be properly cooked and properly handled during food preparation. Due to the potential health risks to consumers, raw milk should be avoided. WHO advises consuming pasteurized milk. If pasteurized milk isn’t available, heating raw milk until it boils makes it safer for consumption.
• WHO has published practical interim guidance to reduce the risk of infection in people exposed to avian influenza viruses.
° Trade and travellers
• WHO advises that travellers to countries with known outbreaks of animal influenza should avoid farms, contact with animals in live animal markets, entering areas where animals may be slaughtered, or contact with any surfaces that appear to be contaminated with animal excreta. Travelers should also wash their hands often with soap and water. All individuals should follow good food safety and hygiene practices.
• WHO does not advise special traveller screening at points of entry or restrictions with regards to the current situation of influenza viruses at the human-animal interface. For recommendations on safe trade in animals and related products from countries affected by these influenza viruses, refer to WOAH guidance.
Links:
WHO Human-Animal Interface web page https://www.who.int/teams/global-influenza-programme/avian-influenza
WHO Influenza (Avian and other zoonotic) fact sheet https://www.who.int/news-room/fact-sheets/detail/influenza-(avian-and-other-zoonotic)
WHO Protocol to investigate non-seasonal influenza and other emerging acute respiratory diseases https://www.who.int/publications/i/item/WHO-WHE-IHM-GIP-2018.2
WHO Public health resource pack for countries experiencing outbreaks of influenza in animals: https://www.who.int/publications/i/item/9789240076884
Cumulative Number of Confirmed Human Cases of Avian Influenza A(H5N1) Reported to WHO https://www.who.int/teams/global-influenza-programme/avian-influenza/avian-a-h5n1-virus
Avian Influenza A(H7N9) Information https://www.who.int/teams/global-influenza-programme/avian-influenza/avian-influenza-a-(h7n9)virus
World Organisation of Animal Health (WOAH) web page: Avian Influenza https://www.woah.org/en/home/
Food and Agriculture Organization of the United Nations (FAO) webpage: Avian Influenza https://www.fao.org/animal-health/avian-flu-qa/en/
WOAH/FAO Network of Expertise on Animal Influenza (OFFLU) http://www.offlu.org/
(...)
{1} This summary and assessment covers information confirmed during this period and may include information received outside of this period.
{2} For epidemiological and virological features of human infections with animal influenza viruses not reported in this assessment, see the reports on human cases of influenza at the human-animal interface published in the Weekly Epidemiological Record here.
{3} World Organisation for Animal Health (WOAH). Avian influenza. Global situation. Available at: https://www.woah.org/en/disease/avian-influenza/#ui-id-2.
{4} Food and Agriculture Organization of the United Nations (FAO). Global Avian Influenza Viruses with Zoonotic Potential situation update. Available at: https://www.fao.org/animal-health/situation-updates/global-aiv-withzoonotic-potential.
{5} World Health Organization (2012). Rapid risk assessment of acute public health events. World Health Organization. Available at: https://iris.who.int/handle/10665/70810.
{6} World Health Organization. Case definitions for the four diseases requiring notification in all circumstances under the International Health Regulations (2005). Available at: https://www.who.int/publications/m/item/case-definitions-for-the-four-diseases-requiring-notification-towho-in-all-circumstances-under-the-ihr-(2005).
{7} World Organisation for Animal Health (WOAH). Avian influenza. Global situation. Available at: https://www.woah.org/en/disease/avian-influenza/#ui-id-2.
{8} Food and Agriculture Organization of the United Nations. Global Avian Influenza Viruses with Zoonotic Potential situation update. Available at: https://www.fao.org/animal-health/situation-updates/global-aiv-withzoonotic-potential/bird-species-affected-by-h5nx-hpai/en.
{9} US CDC. FluView week 17, 8 May 2026 (https://www.cdc.gov/fluview/surveillance/2026-week-17.html).
{10} World Organisation for Animal Health. Statement on High Pathogenicity Avian Influenza in Cattle, 6 December 2024 (https://www.woah.org/en/high-pathogenicity-avian-influenza-hpai-in-cattle/).
{11} World Health Organization. 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_20142022-2024-en.pdf).
{12} World Health Organization. Case definitions for the four diseases requiring notification in all circumstances under the International Health Regulations (2005) (https://www.who.int/publications/m/item/casedefinitions-for-the-four-diseases-requiring-notification-to-who-in-all-circumstances-under-the-ihr-(2005)).
{13} World Health Organization. Manual for the laboratory diagnosis and virological surveillance of influenza (2011) (https://apps.who.int/iris/handle/10665/44518).
{14} World Health Organization. Pandemic influenza preparedness framework for the sharing of influenza viruses and access to vaccines and other benefits, 2nd edition (https://iris.who.int/handle/10665/341850).
{15} World Health Organization. Operational guidance on sharing influenza viruses with human pandemic potential (IVPP) under the Pandemic Influenza Preparedness (PIP) Framework (2017) (https://apps.who.int/iris/handle/10665/259402).
Source:
____
I am an Italian blogger, active since 2005 with main focus on emerging infectious diseases such as avian influenza, SARS, antibiotics resistance, and many other global Health issues. Other fields of interest are: climate change, global warming, geological and biological sciences. My activity consists mainly in collection and analysis of news, public services updates, confronting sources and making decision about what are the 'signals' of an impending crisis (an outbreak, for example). When a signal is detected, I follow traces during the entire course of an event. I started in 2005 my blog ''A TIME'S MEMORY'', now with more than 40,000 posts and 3 millions of web interactions. Subsequently I added an Italian Language blog, then discontinued because of very low traffic and interest. I contributed for seven years to a public forum (FluTrackers.com) in the midst of the Ebola epidemic in West Africa in 2014, I left the site to continue alone my data tracking job.
Abstract
Rapid antigenic evolution of Influenza A viruses (IAVs) enables their escape from strain-specific vaccine immunity, underscoring the need for broadly protective strategies. Here, we describe a modular, adjuvant-free mucosal vaccine platform that elicits potent and cross-protective T cell immunity. The approach uses overlapping CD4+ and CD8+ epitope-dense regions from the consensus IAV M1 and NP proteins, identified through computational and functional screening. These peptides are delivered using polylactic-co-glycolic acid (PLGA) microparticles, engineered for selective uptake by antigen-presenting cells and enabling sustained, pH-responsive antigen release. This design enhances antigen processing and MHC cross-presentation, functionally substituting for a conventional adjuvant. This formulation drives robust activation of primed human as well as murine CD4+ and CD8+ T cells and confers broad protection against homologous (H1N1, H3N2) as well as heterologous (H5N1) IAV strains in immunized mice. Overall, this adjuvant-free dose-sparing platform establishes an adaptable framework for next-generation broadly-protective vaccines against rapidly evolving viruses.
Competing Interest Statement
R.T.Y. and S.T. are co-inventors on an unpublished patent titled Immunogenic peptide(s), composition(s) and application(s) thereof broadly protective against Influenza, Indian patent application number 202541082426. The other authors declare that they have no competing interests.
Funder Information Declared
DBT-ENDFLU, BT/IN/EU-INF/15/RV/19-20
Source:
Link: https://www.biorxiv.org/content/10.64898/2026.03.29.715080v2
____
I am an Italian blogger, active since 2005 with main focus on emerging infectious diseases such as avian influenza, SARS, antibiotics resistance, and many other global Health issues. Other fields of interest are: climate change, global warming, geological and biological sciences. My activity consists mainly in collection and analysis of news, public services updates, confronting sources and making decision about what are the 'signals' of an impending crisis (an outbreak, for example). When a signal is detected, I follow traces during the entire course of an event. I started in 2005 my blog ''A TIME'S MEMORY'', now with more than 40,000 posts and 3 millions of web interactions. Subsequently I added an Italian Language blog, then discontinued because of very low traffic and interest. I contributed for seven years to a public forum (FluTrackers.com) in the midst of the Ebola epidemic in West Africa in 2014, I left the site to continue alone my data tracking job.
ABSTRACT
The Centers of Excellence for Influenza Research and Response (CEIRR) Risk Assessment Pipeline (RAP) integrates surveillance, phenotypic analysis, and computational modeling across six CEIRR centers to evaluate the pandemic potential of influenza A viruses. By generating coordinated data sets from wild and domestic animals and linking them to viral evolution and functional traits, CEIRR RAP supports the Centers for Disease Control and Prevention’s and the World Health Organization’s risk-assessment efforts. The RAP’s data packages thereby enable evidence-based prioritization of global influenza preparedness and response strategies.
Source:
Link: https://journals.asm.org/doi/10.1128/jvi.00545-26
____
I am an Italian blogger, active since 2005 with main focus on emerging infectious diseases such as avian influenza, SARS, antibiotics resistance, and many other global Health issues. Other fields of interest are: climate change, global warming, geological and biological sciences. My activity consists mainly in collection and analysis of news, public services updates, confronting sources and making decision about what are the 'signals' of an impending crisis (an outbreak, for example). When a signal is detected, I follow traces during the entire course of an event. I started in 2005 my blog ''A TIME'S MEMORY'', now with more than 40,000 posts and 3 millions of web interactions. Subsequently I added an Italian Language blog, then discontinued because of very low traffic and interest. I contributed for seven years to a public forum (FluTrackers.com) in the midst of the Ebola epidemic in West Africa in 2014, I left the site to continue alone my data tracking job.
The farm is part of mixed-species premises with several types of animals, including ducks, broiler chickens, Goliath chickens, and rabbits. Two male breeding ducks were purchased at the Passy market on May 8, 2026, in the department of Foundiougne, located in the Fatick region, to restock the flock and ensure mating with the females. One of the newly introduced adult males died from the disease, while the other survived. The quarantine period for the two new ducks was not applied properly. The first symptoms appeared on May 11, 2026, and the first deaths occurred on May 12, 2026. In total, among the ducks, 29 deaths were recorded out of a flock of 50, representing a mortality rate of 58%. As for the Goliath chickens, out of a flock of 11, 4 deaths were recorded, representing a mortality rate of 36.36%. Additionally, 7 other birds were culled by the manager following the appearance of clinical signs.
Source:
Link: https://wahis.woah.org/#/in-review/7593
____
I am an Italian blogger, active since 2005 with main focus on emerging infectious diseases such as avian influenza, SARS, antibiotics resistance, and many other global Health issues. Other fields of interest are: climate change, global warming, geological and biological sciences. My activity consists mainly in collection and analysis of news, public services updates, confronting sources and making decision about what are the 'signals' of an impending crisis (an outbreak, for example). When a signal is detected, I follow traces during the entire course of an event. I started in 2005 my blog ''A TIME'S MEMORY'', now with more than 40,000 posts and 3 millions of web interactions. Subsequently I added an Italian Language blog, then discontinued because of very low traffic and interest. I contributed for seven years to a public forum (FluTrackers.com) in the midst of the Ebola epidemic in West Africa in 2014, I left the site to continue alone my data tracking job.
Abstract
Despite concerns about the spread and pandemic potential of H5N1, there is no commercial H5N1 vaccine. Seasonal influenza vaccines offer some cross-protection against H5N1, but to date there has been no consideration of whether protection differs between the sexes. We investigated immune responses and protection in adult male and female C57BL/6 mice following vaccination with either inactivated H1N1 or H5N1 (LAIV backbone) virus vaccines. Vaccination induced strong homologous antibody responses, with females generating greater total IgG than males against both H1N1 and H5N1 vaccine, which was primarily mediated by greater IgG responses to neuraminidase (NA) than hemagglutinin (HA) protein. IgG cross-recognition of H1N1 also was greater among H5N1 vaccinated females and was primarily caused by greater IgG responses to N1. IgG2b and IgG2c were the primary isotypes generated in response to these vaccines, with females having greater IgG2b responses and greater binding to FcγRIV for avian and human NA than males in response to both homologous and heterologous vaccination. Antibody-dependent complement deposition was measured as an FcR-mediated non-neutralizing response against HA and NA and was robust in both sexes. Vaccinated females had greater neutralizing antibody titers than males against the homologous vaccine virus, with limited cross-neutralizing antibodies detected in either sexes. Neuraminidase inhibition titers were greater in vaccinated females than males against the heterologous virus following H1N1 vaccination and against both the vaccine and heterologous viruses following H5N1 vaccination. When H1N1 and H5N1 vaccinated mice were challenged with a lethal dose of A/Texas/37/2024 H5N1, all H5N1 vaccinated mice were protected, regardless of sex. Among H1N1 vaccinated mice, while both sexes were protected against disease, H1N1 vaccinated females cleared virus faster than their male counterparts. These findings highlight that female-biased NA-specific antibodies result in greater cross-protection and should be considered in studies of influenza vaccines.
Competing Interest Statement
The authors have declared no competing interest.
Funder Information Declared
NIH/NIAID Johns Hopkins Center of Excellence for Influenza Research and Response, 75N93021C00045
Source:
Link: https://www.biorxiv.org/content/10.64898/2026.05.26.728011v1
____
I am an Italian blogger, active since 2005 with main focus on emerging infectious diseases such as avian influenza, SARS, antibiotics resistance, and many other global Health issues. Other fields of interest are: climate change, global warming, geological and biological sciences. My activity consists mainly in collection and analysis of news, public services updates, confronting sources and making decision about what are the 'signals' of an impending crisis (an outbreak, for example). When a signal is detected, I follow traces during the entire course of an event. I started in 2005 my blog ''A TIME'S MEMORY'', now with more than 40,000 posts and 3 millions of web interactions. Subsequently I added an Italian Language blog, then discontinued because of very low traffic and interest. I contributed for seven years to a public forum (FluTrackers.com) in the midst of the Ebola epidemic in West Africa in 2014, I left the site to continue alone my data tracking job.
{Excerpt}
(...)
Time Period: May 17, 2026 - May 23, 2026
-- A(H5) Detection: 7 site(s) (1.6%)
-- No Detection: 438 site(s) (98.4%)
-- No samples: 49 site(s)
(...)
Source:
Link: https://www.cdc.gov/wastewater/emerging-viruses/h5.html?
____
I am an Italian blogger, active since 2005 with main focus on emerging infectious diseases such as avian influenza, SARS, antibiotics resistance, and many other global Health issues. Other fields of interest are: climate change, global warming, geological and biological sciences. My activity consists mainly in collection and analysis of news, public services updates, confronting sources and making decision about what are the 'signals' of an impending crisis (an outbreak, for example). When a signal is detected, I follow traces during the entire course of an event. I started in 2005 my blog ''A TIME'S MEMORY'', now with more than 40,000 posts and 3 millions of web interactions. Subsequently I added an Italian Language blog, then discontinued because of very low traffic and interest. I contributed for seven years to a public forum (FluTrackers.com) in the midst of the Ebola epidemic in West Africa in 2014, I left the site to continue alone my data tracking job.
Abstract
Since 2020, high pathogenicity avian influenza H5Nx viruses of clade 2.3.4.4b have become enzootic in Europe, causing recurrent epidemic waves characterized by extensive reassortment events. Here, we describe the emergence of a single high-fitness genotype (EA-2024-DI) that has driven two consecutive waves, evolving into distinct sub-lineages. While its circulation is ongoing, during the 2025-2026 wave it caused an unprecedented number of cases in wild birds. Using phylodynamic analyses of a large dataset of genomic sequences, we compared the spatial diffusion and host transmission pattern of the EA-2024-DI sub-lineages across the three most recent epidemic waves (2023-2024, 2024-2025 and 2025-2026). We show that the genotype has persisted over time and has spread primarily through wild Anseriformes, but with a marked change in the transmission patterns between the different waves and a shift in the epicenter from Eastern to Central Europe, the latter having emerged as an important hub for virus diffusion throughout Europe. Our results reveal a recent increase in the frequency of viruses from wild and domestic mammals carrying mutations enhancing virus replication in mammalian hosts, highlighting the importance of proactive monitoring of this group of hosts to better understand its role in the virus ecology and evolution.
Competing Interest Statement
The authors have declared no competing interest.
Funder Information Declared
Funded by the European Union under grant agreement (101084171) - (Kappa-Flu). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or REA. Neither the European Union nor the granting authority can be held responsible for them
Support for this work was provided by the European Union within the framework of the activities foreseen by the European Union Reference Laboratory for Avian Influenza and Newcastle Disease under grant agreement 101201937
Source:
Link: https://www.biorxiv.org/content/10.64898/2026.05.25.727580v1
____
I am an Italian blogger, active since 2005 with main focus on emerging infectious diseases such as avian influenza, SARS, antibiotics resistance, and many other global Health issues. Other fields of interest are: climate change, global warming, geological and biological sciences. My activity consists mainly in collection and analysis of news, public services updates, confronting sources and making decision about what are the 'signals' of an impending crisis (an outbreak, for example). When a signal is detected, I follow traces during the entire course of an event. I started in 2005 my blog ''A TIME'S MEMORY'', now with more than 40,000 posts and 3 millions of web interactions. Subsequently I added an Italian Language blog, then discontinued because of very low traffic and interest. I contributed for seven years to a public forum (FluTrackers.com) in the midst of the Ebola epidemic in West Africa in 2014, I left the site to continue alone my data tracking job.
Abstract
During 2022–2024, a highly pathogenic avian influenza virus (HPAIV) H5N1 strain, designated A/Seagull/Hebei/qhd6/2024 (H5N1), was isolated from migratory birds in Beidaihe National Wetland Park, North China. Phylogenetic analyses revealed that its hemagglutinin (HA) gene belongs to the 2.3.4.4b clade, while the neuraminidase (NA) gene and internal genes clustered with strains originating from multiple continents, consistent with a transcontinental reassortment event. The virus also exhibited 90.1–98.1% nucleotide homology with human-derived H5N1 isolates. Molecular characterization identified key virulence-associated mutations, including the classic HPAIV HA cleavage site, HA-T160A (associated with enhanced human receptor-binding capacity), and NA-I117T (potentially linked to drug resistance). BALB/c mouse infection experiments confirmed systemic replication and high pathogenicity of strain qhd6, with a 50% lethal dose (LD50) of 0.95 log10EID50/mL. Antigenic analysis revealed good cross-reactivity with the widely used H5-Re14 vaccine strain. This study reports the identification, in Beidaihe National Wetland Park, of an HPAIV H5N1 strain whose genetic characteristics suggest intercontinental reassortment and indicate cross-species transmission risk. It clarifies the genetic characteristics and pathogenicity of this strain, providing an important theoretical and practical basis for precise surveillance, risk early warning, and comprehensive prevention and control of AIV at migratory bird stopover sites in North China.
Source:
Link: https://www.mdpi.com/1999-4915/18/6/595
____
I am an Italian blogger, active since 2005 with main focus on emerging infectious diseases such as avian influenza, SARS, antibiotics resistance, and many other global Health issues. Other fields of interest are: climate change, global warming, geological and biological sciences. My activity consists mainly in collection and analysis of news, public services updates, confronting sources and making decision about what are the 'signals' of an impending crisis (an outbreak, for example). When a signal is detected, I follow traces during the entire course of an event. I started in 2005 my blog ''A TIME'S MEMORY'', now with more than 40,000 posts and 3 millions of web interactions. Subsequently I added an Italian Language blog, then discontinued because of very low traffic and interest. I contributed for seven years to a public forum (FluTrackers.com) in the midst of the Ebola epidemic in West Africa in 2014, I left the site to continue alone my data tracking job.
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
_____
I am an Italian blogger, active since 2005 with main focus on emerging infectious diseases such as avian influenza, SARS, antibiotics resistance, and many other global Health issues. Other fields of interest are: climate change, global warming, geological and biological sciences. My activity consists mainly in collection and analysis of news, public services updates, confronting sources and making decision about what are the 'signals' of an impending crisis (an outbreak, for example). When a signal is detected, I follow traces during the entire course of an event. I started in 2005 my blog ''A TIME'S MEMORY'', now with more than 40,000 posts and 3 millions of web interactions. Subsequently I added an Italian Language blog, then discontinued because of very low traffic and interest. I contributed for seven years to a public forum (FluTrackers.com) in the midst of the Ebola epidemic in West Africa in 2014, I left the site to continue alone my data tracking job.
Abstract
Highly pathogenic avian influenza A(H5N1) virus exhibits a strong tropism for the bovine mammary gland, challenging our understanding of influenza A virus host range and tissue specificity. We performed experimental studies with an influenza A(H5N1) B3.13 genotype virus in female lactating dairy cattle to define the infectious dose, routes of exposure, and factors linked to morbidity and mortality. Here, we demonstrate that intramammary inoculation with as few as 10 TCID50 establishes a robust infection and shedding of high-titer virus in milk. Despite this low infectious dose, H5N1 does not readily transmit via contaminated milking equipment and close contact with infected animals. High-dose intramammary exposure results in severe disease and mortality, while respiratory and oral exposures are less likely to establish productive infection and associated morbidity. This study challenges current hypotheses of H5N1 transmission on dairy farms, raising important questions about potential agent, host, or environmental cofactors contributing to viral spread.
Source:
Link: https://www.nature.com/articles/s41467-026-73490-6
____
I am an Italian blogger, active since 2005 with main focus on emerging infectious diseases such as avian influenza, SARS, antibiotics resistance, and many other global Health issues. Other fields of interest are: climate change, global warming, geological and biological sciences. My activity consists mainly in collection and analysis of news, public services updates, confronting sources and making decision about what are the 'signals' of an impending crisis (an outbreak, for example). When a signal is detected, I follow traces during the entire course of an event. I started in 2005 my blog ''A TIME'S MEMORY'', now with more than 40,000 posts and 3 millions of web interactions. Subsequently I added an Italian Language blog, then discontinued because of very low traffic and interest. I contributed for seven years to a public forum (FluTrackers.com) in the midst of the Ebola epidemic in West Africa in 2014, I left the site to continue alone my data tracking job.
Abstract
Highly pathogenic avian influenza (HPAI) viruses from clade 2.3.4.4 have caused recurrent outbreaks in poultry since 2014. In the Republic of Korea, clade 2.3.4.4b viruses have driven five epidemic waves, yet the factors underlying HPAI introduction and farm-to-farm spread remain poorly understood. We compiled hemagglutinin gene sequences of clade 2.3.4.4b viruses from wild birds and poultry in the Republic of Korea (October 2016–March 2024) and reconstructed dispersal dynamics using Bayesian phylogeography. Dispersal patterns suggest that domestic duck farms in the western provinces likely form a key interface for spillover from wild birds into poultry. Mixed-effects generalized linear models showed that both wild-to-poultry and farm-to-farm transition rates were positively associated with the number of poultry farms in the destination province, while wild-to-poultry rates were further associated with higher avian influenza virus infection probability among wild birds. Wild-to-poultry transition rates were lower in 2020–2024 than in 2016–2018, which may reflect strengthened interventions. These findings suggest that poultry farm abundance and introduction pressure from wild birds jointly shape the spatial dynamics of HPAI introduction and spread. More broadly, these factors may provide operational indicators to guide risk-based surveillance and control strategies.
Competing Interest Statement
The authors have declared no competing interest.
Source:
Link: https://www.biorxiv.org/content/10.64898/2026.05.21.726857v1
____
I am an Italian blogger, active since 2005 with main focus on emerging infectious diseases such as avian influenza, SARS, antibiotics resistance, and many other global Health issues. Other fields of interest are: climate change, global warming, geological and biological sciences. My activity consists mainly in collection and analysis of news, public services updates, confronting sources and making decision about what are the 'signals' of an impending crisis (an outbreak, for example). When a signal is detected, I follow traces during the entire course of an event. I started in 2005 my blog ''A TIME'S MEMORY'', now with more than 40,000 posts and 3 millions of web interactions. Subsequently I added an Italian Language blog, then discontinued because of very low traffic and interest. I contributed for seven years to a public forum (FluTrackers.com) in the midst of the Ebola epidemic in West Africa in 2014, I left the site to continue alone my data tracking job.
Abstract
The global emergence of the avian influenza virus (AIV) H5N1 clade 2.3.4.4B since 2016 has caused substantial losses in wild bird and poultry populations, along with heightened risks of transmission to humans and other mammals. Vaccination of poultry has been a key strategy to curb the virus’s spread and mitigate its socioeconomic impact. This report describes an outbreak of high pathogenicity avian influenza virus (HPAIV) H5N1 clade 2.3.4.4B in a flock of 15,000 brown layer chickens (170 days old), all of which had received a four-dose vaccination regimen with H5N1/H5N8 commercial vaccines at 17, 50, 100, and 125 days of age. Despite this vaccination history, H5N1 infection was confirmed approximately seven weeks post-vaccination. H5N1 infection was confirmed by RT-qPCR, virus isolation, and full genome sequencing covering all eight gene segments, followed by phylogenetic and molecular analyses. Clinical signs included reduced feed intake, decreased egg production, and a cumulative mortality rate of 35% over 52 days. Hemagglutination inhibition (HI) testing with various H5 antigens revealed inconsistent antibody titers (geometric mean: 4.0 to 9.1 log2). Genetic analysis of the full-length HA and NA gene sequences further revealed strong similarity to contemporaneous H5N1 clade 2.3.4.4B strains circulating in Egypt, with multiple mutations in the HA head domain, particularly near immunogenic epitopes and receptor binding sites. These findings highlight the limitations of current vaccination strategies under conditions of antigenic mismatch and complex immunization schedules, emphasizing the need for improved vaccine matching and continuous molecular surveillance. To improve outbreak management in poultry, enhanced vaccination protocols, stringent biosecurity measures, and rigorous monitoring practices are critical.
Source:
Link: https://www.mdpi.com/1999-4915/18/6/589
____
I am an Italian blogger, active since 2005 with main focus on emerging infectious diseases such as avian influenza, SARS, antibiotics resistance, and many other global Health issues. Other fields of interest are: climate change, global warming, geological and biological sciences. My activity consists mainly in collection and analysis of news, public services updates, confronting sources and making decision about what are the 'signals' of an impending crisis (an outbreak, for example). When a signal is detected, I follow traces during the entire course of an event. I started in 2005 my blog ''A TIME'S MEMORY'', now with more than 40,000 posts and 3 millions of web interactions. Subsequently I added an Italian Language blog, then discontinued because of very low traffic and interest. I contributed for seven years to a public forum (FluTrackers.com) in the midst of the Ebola epidemic in West Africa in 2014, I left the site to continue alone my data tracking job.
{Excerpt}
(...)
Time Period: May 10, 2026 - May 16, 2026
-- A(H5) Detection: 4 site(s) (1.0%)
-- No Detection: 413 site(s) (99.0%)
-- No samples: 81 site(s)
(...)
Source:
Link: https://www.cdc.gov/wastewater/emerging-viruses/h5.html?
____
I am an Italian blogger, active since 2005 with main focus on emerging infectious diseases such as avian influenza, SARS, antibiotics resistance, and many other global Health issues. Other fields of interest are: climate change, global warming, geological and biological sciences. My activity consists mainly in collection and analysis of news, public services updates, confronting sources and making decision about what are the 'signals' of an impending crisis (an outbreak, for example). When a signal is detected, I follow traces during the entire course of an event. I started in 2005 my blog ''A TIME'S MEMORY'', now with more than 40,000 posts and 3 millions of web interactions. Subsequently I added an Italian Language blog, then discontinued because of very low traffic and interest. I contributed for seven years to a public forum (FluTrackers.com) in the midst of the Ebola epidemic in West Africa in 2014, I left the site to continue alone my data tracking job.
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).
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{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).
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{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/).
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{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).
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{23} GISAID.
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{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).
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{43} WOAH. Avian influenza vaccination: why it should not be a barrier to safe trade, December 2023 (www.woah.org/app/uploads/2023/12/en-woah-policybrief-avianinfluenzavaccinationandtrade.pdf).
{44} WOAH. Case definition for infection of bovines with influenza a viruses of high pathogenicity in poultry (high pathogenicity avian influenza in cattle), 29 October 2025 (https://www.woah.org/app/uploads/2025/03/2025-10-case-definiton-hpai-cattle-2.pdf).
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{47} Animal and Plant Health Inspection Service (APHIS), USDA. APHIS Recommendations for Highly Pathogenic Avian Influenza (HPAI) H5N1 Virus in Livestock For Workers, 12 April 2024 (www.aphis.usda.gov/sites/default/files/recommendations-workers-hpai-livestock.pdf).
{48} WHO. Guidelines for the clinical management of severe illness from influenza virus infections. 2022 (https://apps.who.int/iris/handle/10665/352453).
{49} WHO. WHO guidance on the use of licensed human influenza A(H5) vaccines for the interpandemic and emergence periods. Weekly Epidemiological Record, 100(51), 643 - 660 (https://iris.who.int/handle/10665/384548).
{50} FAO. Preliminary rapid risk assessment of foodborne avian influenza A (H5N1) virus. 14 June 2024 (https://openknowledge.fao.org/server/api/core/bitstreams/ca83524e-b3f9-4abe-b52b-dea213227fcf/content).
{51} Joint FAO/WHO Codex Alimentarius Commission. Codex Alimentarius: Code of hygienic practice for milk and milk products (http://www.fao.org/fileadmin/user_upload/livestockgov/documents/CXP_057e.pdf).
DISCLAIMER
The designations employed and the presentation of the material in this publication do not imply the expression of any opinion whatsoever on the part of the World Health Organization (WHO), the Food and Agriculture Organization of the United Nations (FAO) or of the World Organisation for Animal Health (WOAH) concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. All reasonable precautions have been taken by WHO, FAO and WOAH to verify the information contained in this publication. However, the published material is being distributed without warranty of any kind, either expressed or implied. The responsibility for the interpretation and use of the material lies with the reader. In no event shall WHO, FAO and WOAH be liable for damages arising from its use.
© FAO, WHO, WOAH, 2026
Source:
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I am an Italian blogger, active since 2005 with main focus on emerging infectious diseases such as avian influenza, SARS, antibiotics resistance, and many other global Health issues. Other fields of interest are: climate change, global warming, geological and biological sciences. My activity consists mainly in collection and analysis of news, public services updates, confronting sources and making decision about what are the 'signals' of an impending crisis (an outbreak, for example). When a signal is detected, I follow traces during the entire course of an event. I started in 2005 my blog ''A TIME'S MEMORY'', now with more than 40,000 posts and 3 millions of web interactions. Subsequently I added an Italian Language blog, then discontinued because of very low traffic and interest. I contributed for seven years to a public forum (FluTrackers.com) in the midst of the Ebola epidemic in West Africa in 2014, I left the site to continue alone my data tracking job.
