Abstract
Replication of influenza A virus in human nasal epithelium affects transmissibility and disease. We compared virus replication and immune responses in human nasal epithelium infected with seasonal and highly pathogenic avian influenza A(H5N1) viruses. Contemporary H5N1 viruses replicated better than the historical isolate; however, interferon response to B3.13 genotype viruses was dampened.
Source:
Link: https://wwwnc.cdc.gov/eid/article/32/5/26-0053_article
____
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) A(H5) viruses have caused sporadic human infections since 1997, with recent detections in the Americas and Asia. However, the evolutionary dynamics of different HPAI A(H5) viruses at the animal–human interface, along with their associated disease severity, propensity for animal-to-human (zoonotic) spillover, and human-to-human transmission potential, remain unclear. Here, we combine available genetic and epidemiological data with mechanistic models to better understand the global spread of HPAI A(H5) viruses that spilled over to humans in 1997–2025. Analysis of 7445 subsampled hemagglutinin gene sequences revealed frequent regional succession of HPAI A(H5) virus clades that varied by geographic location. The 1104 reported human HPAI A(H5) cases exhibited subtype- and clade-specific heterogeneity in age, gender, and exposure sources (p < 0.001). After adjusting for under-reporting, we estimated case-fatality risk to be low for HPAI A(H5N1) clade 2.3.4.4b (0.7%, 95%CI: 0.02%–3.9%) and for A(H5N6) clades 2.3.4x (0%, 0%–1.1%) and 2.3.4.4b (1.6%, 0.7%–3.2%), compared with other A(H5) clades (range: 4.7%–15.0%). We also show that, while the transmissibility of HPAI A(H5) viruses between humans remains very low to date (mean Rt: 0.10–0.23), zoonotic transmission has increased with the emergence of bovine-origin clade 2.3.4.4b (incidence: 7.85 per million people per year), relative to other avian-origin A(H5) clades (range: 1.54–5.04 per million people per year). Although other factors such as exposure sources, routes of transmission, immune function, underlying medical conditions, and clinical management can influence outcomes of case-patients, these findings highlight the ongoing pandemic threat posed by HPAI A(H5) viruses and the need for ongoing comprehensive surveillance, genotypic and phenotypic characterization, and preparedness.
Source:
Link: https://academic.oup.com/nsr/article/13/7/nwaf471/8317928
____
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
Background
Highly pathogenic avian influenza (HPAI) viruses, particularly subtypes such as H5N1 and H7N9, have caused widespread outbreaks in wild birds, poultry, livestock and occasionally humans, raising concerns about cross-species transmission and pandemic potential. Effective control and surveillance strategies require a thorough understanding of HPAI transmission dynamics, which can be supported by mathematical modelling.
Objective
This scoping review aimed to identify mechanistic models used to study HPAI transmission. Specifically, we sought to categorize model types, describe their application contexts (e.g., wild birds, poultry, livestock, and humans), and highlight modelling gaps relevant to understanding and mitigating the risks of HPAI spread.
Methods
Following PRISMA guidelines and the PRISMA extension for scoping reviews (PRISMA-ScR), we conducted systematic searches of PubMed and Web of Science to identify peer-reviewed studies employing deterministic and stochastic models to analyze HPAI transmission. Eligible articles published between January 2023 and June 2025 were screened and grouped by model structure, host populations, transmission pathways, and modelling objectives.
Results
After screening, 30 studies published after 2023 were included in this scoping review. Compartmental models were the most common (26 studies), with 16 deterministic and 10 stochastic approaches. These models were primarily used to describe transmission among wild birds, poultry, livestock, and humans and to evaluate interventions such as culling, vaccination, and movement restrictions. Agent-based models (2 studies) captured individual-level interactions and spatial heterogeneity, while network models (2 studies) represented contact structures and transmission pathways between farms or species.
Conclusions
Currently, mechanistic modelling of HPAI is dominated by compartmental approaches, including both deterministic and stochastic formulations, whereas agent-based and network models remain relatively underused. Although most studies focus on transmission in wild birds and poultry, and in some cases spillover infections to humans, few explicitly examine infection dynamics in livestock or in transmission between livestock and humans, despite the importance of livestock (e.g., cattle) as potential intermediaries in human infection. Key gaps persist in the integration of empirical data, representation of multi-host interactions, and evaluation of realistic intervention strategies. Addressing these limitations is essential to improve predictive accuracy and to strengthen the role of modelling in informing HPAI surveillance and control.
Source:
Link: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0347929
____
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 23 January to 31 March 2026, based on reporting date, detections of influenza A(H5N1) in four humans, influenza A(H9N2) in five humans, influenza A(H10N3) in one human, an influenza A(H1N1) variant ((H1N1)v) virus in one human, an influenza A(H1N2)v virus in one human, and influenza A(H3N2)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.
-- The occurrence of sustained human-to-human transmission of these viruses is currently considered unlikely.
-- Although human infections with viruses of animal origin are infrequent, they are not unexpected at the human-animal interface.
Risk management:
-- Candidate vaccine viruses (CVVs) for zoonotic influenza viruses for pandemic preparedness purposes were reviewed and updated at the February 2026 WHO consultation on influenza vaccine composition for use in the northern hemisphere 2026-2027 influenza season.
-- A detailed summary of zoonotic influenza viruses characterized since September 2025 is published here and updated CVVs lists are published here.
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 - Current situation:
-- Since the last risk assessment of 22 January 2026, four laboratory-confirmed human cases of A(H5N1) infection were detected in Bangladesh (one case) and Cambodia (three cases).
-- A(H5N1), Bangladesh
- On 9 February 2026, the National International Health Regulations Focal Point of Bangladesh notified WHO of a laboratory-confirmed human case of avian influenza A(H5) infection in a child from Chattogram Division.
- The patient, with no known comorbidities, developed symptoms on 21 January 2026 and was admitted to hospital on 28 January.
- A nasopharyngeal swab was collected on 29 January as part of the Hospital-based Influenza Surveillance (HBIS) platform for influenza-like illness (ILI) and severe acute respiratory infection (SARI) sentinel surveillance in Bangladesh.
- The patient was referred to a specialized private hospital and admitted to intensive care on 31 January.
- The patient died on 1 February.
- On 7 February, the Institute of Epidemiology, Disease Control and Research (IEDCR), serving as the National Influenza Centre (NIC), received and tested the sample, confirming influenza A(H5) by realtime reverse transcription polymerase chain reaction (RT-PCR) on the same day.
- Virus characterization and whole genome sequencing was conducted at International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), which confirmed that the A(H5N1) virus belongs to clade 2.3.2.1a of highly pathogenic avian influenza A(H5N1) virus (Gs/GD lineage), similar to the clade of viruses circulating in local poultry since around 2011.
- Genetic sequence data are available in GISAID (EPI_ISL_20367262; submission date 19 Feb 2026; Institute of Epidemiology, Disease Control & Research (IEDCR)).
- The case had exposure to household poultry, with two ducks and one chicken reportedly dying shortly before the case’s illness onset.
- Animal and environmental samples were collected and tested with RT-PCR and serology by the zoonotic investigation team of icddr,b.
- Two samples from ducks in the community and two samples from chicken meat in the freezer of household tested positive for influenza A(H5).
- Samples from symptomatic close human contacts tested negative for influenza.
- This is the first confirmed human case of avian influenza A(H5) reported in Bangladesh in 2026.
- In 2025, four human cases of avian influenza A(H5) were reported.
- 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}
-- A(H5N1), Cambodia
- Between 15 February and 31 March 2026, Cambodia notified WHO of three laboratory-confirmed cases of A(H5N1) virus infection.
(...)
- All cases above had exposure to sick or dead backyard poultry.
- The first case was detected through SARI surveillance.
- The other two cases were detected following the detection of A(H5N1) in sick and dead poultry which initiated deployment of rapid response teams from the public health sector and active case finding.
- The last case was identified as having had exposure to sick and dead poultry, sampled and then developed ILI symptoms.
- Three human infections with A(H5N1) viruses have been confirmed in Cambodia in 2026 and none have been fatal.
- Influenza A(H5N1) viruses continue to be detected in domestic birds in Cambodia in 2026, including in areas where human cases have been detected.{9}
- 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(H9N2), China
- Between 9 February and 20 March 2026, China notified WHO of four laboratory-confirmed cases of A(H9N2) virus infection.
(...)
-- A(H9N2), Italy, ex-Senegal {10}
- On 21 March 2026, Italy notified WHO of the detection of A(H9N2) virus in an adult male.
- The case had travelled to Senegal for more than six months and returned to Italy in mid-March 2026.
- Upon arrival in Italy, the case sought medical care, presenting with fever and persistent cough that had been present since mid-January.
- Laboratory investigations conducted on a bronchoalveolar lavage specimen on 16 March showed a positive Mycobacterium tuberculosis result, as well as detection of an un-subtypeable influenza A virus.
- The case was admitted to an isolation room under airborne precautions in a negative-pressure room and received antitubercular and antiviral treatment.
- As of 24 March, the patient was clinically stable and improving.
- On 20 March 2026, the regional reference laboratory confirmed the A(H9) subtype, and on 21 March, influenza A(H9N2) was confirmed by next-generation sequencing.
- Initial genetic findings suggest the infection was likely acquired from an avian source linked to Senegal.
- Additional samples have been sent to Italy’s National Influenza Center, where further characterization confirmed virus subtype Influenza A(H9N2), with close genetic similarity to strains previously identified in poultry in Senegal.
- No direct exposure to animals, wildlife or rural environments was identified.
- There was also no reported contact with symptomatic or confirmed human cases.
- Further epidemiological investigations on the source of exposure are ongoing.
- Contacts identified in Senegal were asymptomatic.
- All identified and traced contacts in Italy have tested negative for influenza and completed the period of active monitoring for the onset of symptoms and the quarantine required by national guidelines.
- Human infections with influenza A(H9) viruses have been reported from countries in Africa and Asia, where these viruses are also detected in poultry.
- This is the first imported human case of avian influenza A(H9N2) reported in the European Region.
-- 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, therefore sustained human-to-human transmission is thus currently considered unlikely.
- 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, such as in the case reported by Italy.
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.
-- A(H10N3), China
- On 9 February 2026, China notified WHO of one laboratory-confirmed case of human infection with an avian influenza A(H10N3) virus in a 34-year-old man from Guangdong province who developed symptoms on 29 December 2025.
- On 1 January 2026, he was admitted to hospital and diagnosed with severe pneumonia, severe acute respiratory distress syndrome (ARDS) and sepsis.
- Oseltamivir treatment was initiated on 3 January.
- The patient's condition was stable at the time of reporting.
- On 12 January, the sample was sent to the provincial laboratory for testing.
- The result was positive for A(H10N3). On 14 January, the National Influenza Center confirmed the positive result.
- The patient works near two establishments that keep live poultry on the premises and chickens are present at the household.
- Environmental samples collected from sites related to likely poultry exposure, including the patient's home, the workplace and a nearby poultry market tested negative for A(H10N3) influenza virus.
- No further cases were detected among contacts of these cases.
- A total of 98 close contacts of the patient were traced.
- Since 2021, a total of seven cases of human avian influenza A(H10N3) virus infection have been reported globally and all were from China.
-- Risk Assessment for avian influenza A(H10N3):
- 1. What is the global public health risk of additional human cases of infection with avian influenza A(H10N3) viruses?
Human infections with avian influenza A(H10) viruses have been detected and reported previously.
The circulation and epidemiology of these viruses in birds have been previously reported.{12}
Avian influenza A(H10N3) viruses with different genetic characteristics have been detected previously in wild birds since the 1970s and more recently spilled over to poultry in some countries.
As long as the virus continues to circulate in birds, further human cases can be expected but remain unusual.
The impact to public health if additional sporadic cases are detected is minimal.
The overall global public health risk of additional sporadic human cases is low.
- 2. What is the likelihood of sustained human-to-human transmission of avian influenza A(H10N3) viruses?
No sustained human-to-human transmission has been identified associated with the event described above or past events with human cases of influenza A(H10N3) viruses.
Current epidemiologic and virologic evidence suggests that contemporary influenza A(H10N3) viruses assessed by the Global Influenza Surveillance and response System (GISRS) have not acquired the ability of sustained transmission among humans, therefore sustained human-to-human transmission is thus currently considered unlikely.
- 3. What is the likelihood of international spread of avian influenza A(H10N3) 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 based on current limited evidence.
Swine influenza viruses in humans
-- Influenza A(H1N1)v, China
- On 20 March 2026, China notified WHO of a laboratory-confirmed case of A(H1N1)v influenza virus infection in a child from Yunnan province.
- The patient had onset of illness on 30 January 2026, was hospitalized on 2 February with pneumonia, and recovered in a few days.
- The patient had reported exposure to domestic pigs prior to illness onset.
-- Influenza A(H1N2)v, China
- On 3 February 2026, China notified WHO of a laboratory-confirmed case of A(H1N2)v influenza virus infection in a child from Yunnan province.
- The patient had onset of mild illness on 20 January 2026, and the infection was laboratory-confirmed on 2 February 2026.
- The patient had reported exposure to domestic pigs prior to illness onset. This case and the one above are not epidemiologically linked.
-- Influenza A(H3N2)v, Brazil
- On 26 January 2026, Brazil notified WHO of a laboratory-confirmed case of A(H3N2)v influenza virus infection.
- On 1 September 2025, a male child residing in the state of Mato Grosso do Sul presented with ILI symptoms and was taken to a health unit on 2 September.
- The patient had no reported comorbidities or recent travel history and reported being vaccinated against seasonal influenza in the last campaign.
- On 9 September, a respiratory sample was collected at the health unit, which is a sentinel unit for ILI.
- On 12 September, the Central Public Health Laboratory of Mato Grosso do Sul (Lacen/MS) reported that the RT-qPCR test for influenza A virus subtyping amplified the influenza A marker along with the H3 marker, indicating a swine-origin variant of the influenza H3 virus.
- The sample was sent to the National Influenza Center (NIC) of the Adolfo Lutz Institute, where the A(H3N2)v was confirmed by molecular tests and genomic sequencing.
- The sequences were entered into GISAID on 1 October.
- The sample was also shared with the WHO Collaborating Centre at the US Centers for Disease Control and Prevention (CDC), where it was genomically and antigenically characterized.
- An epidemiological investigation was conducted, which identified the case as a student at an agricultural school where pigs and laying hens are raised, although the institution's coordinators reported that the students had not had direct contact with pigs recently.
- It was reported that the case had contact with classmates who presented ILI symptoms during this period.
- All household contacts were vaccinated against seasonal influenza in the 2025 season, except for the patient's mother.
- To date, no other human cases of infection with the A(H3N2)v virus have been detected in association with this case.
-- Risk Assessment:
- 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 events described above.
Current evidence suggests that contemporary swine influenza viruses have not acquired the ability of sustained transmission among humans, therefore sustained human-to-human transmission is thus currently considered unlikely.
- 3. What is the likelihood of international spread of swine influenza viruses by travelers?
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.
For more information on zoonotic influenza viruses, see the report from the WHO Consultation on the Composition of Influenza Virus Vaccines for Use in the 2026-2027 Northern Hemisphere Influenza Season that was held on 23-26 February 2026 at this link.
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.{11}
- 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).{12,13}
- State Parties to the IHR (2005) are required to immediately notify WHO of any laboratory-confirmed{14} case of a recent human infection caused by an influenza A virus with the potential to cause a pandemic{15}.
- 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 basis16 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} World Organisation for Animal Health. WAHIS. https://wahis.woah.org/#/in-review/7409.
{10} World Health Organization. World Health Organization (10 April 2026). Disease Outbreak News: Avian Influenza A(H9N2) in Italy (https://www/who.int/emergencies/disease-outbreak-news/item/2026-DON597).
{11} 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/).
{12} 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).
{13} 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)).
{14} World Health Organization. Manual for the laboratory diagnosis and virological surveillance of influenza (2011) (https://apps.who.int/iris/handle/10665/44518).
{15} 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).
{16} 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:
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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.
Abstract
Background and Aim:
Middle East respiratory syndrome coronavirus (MERS-CoV) remains a persistent zoonotic threat more than a decade after its first detection, with Saudi Arabia continuing to be the global epicenter of human infections and the main reservoir interface through dromedary camels. Despite ongoing surveillance, advances in molecular diagnostics, and research on vaccines and therapeutics, sporadic zoonotic spillovers and healthcare-associated outbreaks still occur, showing that current prevention strategies are still not enough. This review compiles current evidence from epidemiological studies, camel reservoir research, genomic monitoring, and public health reports published between 2012 and April 2025 to identify the key gaps preventing effective containment. Special focus is given to recent genomic discoveries, including post-2022 clade B sublineages, recombination events, and spike protein changes that might affect transmission and the effectiveness of countermeasures. Available data suggest that MERS-CoV epidemiology is driven by repeated camel-to-human transmission, followed by occasional amplification in healthcare settings rather than sustained community spread. High seroprevalence and frequent detection of viral RNA in juvenile camels, seasonal gathering in markets, and extensive animal movement networks contribute to ongoing viral circulation at the animal–human interface. Genomic studies consistently show close phylogenetic relationships between camel and human isolates, confirming recurrent zoonotic transmissions. However, fragmented surveillance systems, delayed genomic data integration, inconsistent biosecurity practices, and limited field evidence for camel vaccination pose major barriers to control. Additionally, hospital outbreaks continue to occur due to delayed diagnosis, overcrowding, and incomplete adherence to infection-prevention protocols, underscoring the need for improved clinical preparedness. Based on the integrated synthesis of epidemiological, veterinary, and genomic evidence, this review proposes an implementation-focused One Health genomic framework tailored to the Saudi context. The proposed roadmap highlights real-time connection of human and camel surveillance, expands genomic sequencing capacity, targets vaccination strategies in camels and high-risk human populations, standardizes biosecurity measures in markets and abattoirs, and strengthens infection control systems in healthcare facilities. Alignment with national governance structures and Saudi Vision 2030 offers a practical pathway for coordinated multi-sectoral action. This review concludes that MERS-CoV is unlikely to be eradicated soon, but it can be effectively managed through a genomics-enabled, operational One Health approach that combines surveillance, vaccination, clinical preparedness, and policy coordination. The model outlined here provides a scalable way to reduce zoonotic spillover risk and strengthen readiness against future coronavirus and emerging zoonotic threats.
Source:
Link: https://veterinaryworld.org/Vol.19/March-2026/29.php
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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.
{Excerpts}
(...)
{-- H5N1:}
- Date of report: 22/04/2026
- Country: Cambodia
- Province / Region: Svay Rieng province
- District / City: Romduol district
- Sex: Female
- Age: 66
- Condition at time of reporting: Hospitalised
- Subtype of virus: H5N1
(...)
Source:
Link: https://www.chp.gov.hk/files/pdf/2026_avian_influenza_report_vol22_wk17.pdf
____
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}
PHNOM PENH (ANTARA) - A 66-year-old woman from Svay Rieng province, southeastern Cambodia, has been confirmed positive for H5N1 bird flu, becoming the fourth case in 2026, the Ministry of Health said in a statement on Wednesday.
The victim, who lives in Trapaing Thkov village in Romduol district, was confirmed positive for the virus by the Cambodian National Institute of Public Health on Tuesday (April 21).
The patient is currently being quarantined at a hospital under intensive care by a team of doctors, the statement said.
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
Identifying viruses with zoonotic potential on the basis of their ability to enter human cells is a critical component of pandemic prediction, prevention and preparedness. Here using a computational approach that retains maximum phylogenetic diversity, we selected an optimal subset of alphacoronavirus spike proteins to screen against broad coronavirus receptor libraries. Most of the selected spike proteins did not use any of the established coronavirus receptors. However, the pseudotyped spike protein of Cardioderma cor (heart-nosed bat) coronavirus KY43 (CcCoV-KY43) could enter human cells. Using a recombinant CcCoV receptor-binding domain (RBD) and a human receptor screening platform, we identified direct interactions with the human CEACAM proteins CEACAM3, CEACAM5 and CEACAM6. Overexpression of human CEACAM6—a protein widely expressed in the human lung—conferred permissivity to otherwise refractory human cells. A crystal structure showed that the RBD binds the amino-terminal IgV-like domain of human CEACAM6. Immune surveillance studies using sera of individuals from the Taveta region of Kenya, where CcCoV-KY43 was identified, did not show significant evidence of recent spillover. Wider characterization of alphacoronaviruses related to CcCoV-KY43 showed that human CEACAM6 is used by two other CcCoVs collected in Kenya. Moreover, there was more restricted nonhuman CEACAM6 tropism for viruses isolated from Rhinolophus bats from Russia and China. Thus, alphacoronaviruses that use CEACAM6 are probably geographically widespread, and viruses from East Africa show potential for transmission to humans.
Source:
Link: https://www.nature.com/articles/s41586-026-10394-x
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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.
Abstract
The first influenza A(H5N1) human case associated with the A(H5N1) dairy cattle outbreak in the United States was identified in April 2024. The U.S. CDC response to this outbreak was activated days later and remained active until July 2025. During this time, 70 human cases of influenza A(H5N1) were detected with a range of epidemiological links to sources of exposure. Next-generation sequencing (NGS) of human samples was an effectual mechanism for tracking and analyzing the outbreak evolution throughout the response. Due to the specimens’ importance and their variable physical quality, an assortment of laboratory methods was utilized including influenza segment-specific amplification, enrichment capture, short-read, and long-read sequencing. Combining these methods allowed for high-quality genomic data production with rapid turnaround times—typically 2 days from sample receipt to public database submission. By leveraging replicate sequencing, enrichment capture, and sequencing of diagnostic amplicons, valuable genomic data could be produced directly from human clinical specimens that would have normally been considered too weak for routine virologic surveillance sequencing. The resulting assemblies were characterized and analyzed by CDC and shared with local and state public health authorities to facilitate case investigations and risk assessment. These data were further used for phylogenetic analyses of viruses from human cases to investigate likely animal-to-human transmission events and identify clusters within the outbreak that might indicate trends in the types of exposures. Through the adaptable laboratory workflow and the rapid release of viral genomic data, the public health risk mitigation strategies could be evaluated and adjusted in real time.
Source:
Link: https://www.mdpi.com/1999-4915/18/4/482
____
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}
(...)
Avian influenza A(H9N2):
-- Guangdong Province:
1) A five-year-old boy with onset on February 23, 2026.
-- Jiangxi Province:
2) A two-year-old boy with onset on March 20, 2026.
-- Yunnan Province:
3) A two-year-old girl with onset on March 3, 2026.
(...)
Source:
Link: https://www.chp.gov.hk/files/pdf/2026_avian_influenza_report_vol22_wk16.pdf
____
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 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
____
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.
Recently, online discussions have focused on a study published in the international journal *Nature Microbiology*, which suggests that *Cryptant Dead Noda Virus* (CMNV), found in aquatic animals, may have the potential to spread across species to humans, potentially causing persistent high-tension viral anterior uveitis (POH-VAU).
The Centers for Disease Control (CDC) stated that currently only China has reported suspected human cases of CMNV, distributed across 18 provinces with high aquaculture activity.
Major international public health organizations such as the WHO, the US CDC, and the European Centre for Disease Prevention and Control (ECDC) have not reported any CMNV-related cases or listed it as an urgent threat.
The CDC assesses the risk of domestic transmission as extremely low and will continue monitoring with agricultural authorities.
The CDC further explained that the study infers that human infection with CMNV may be related to handling or consuming raw seafood; however, further evidence is needed to confirm whether this virus has the ability to effectively infect human eye tissue.
The Taiwan Centers for Disease Control (CDC) emphasizes that there have been no large-scale human outbreaks or community transmission events caused by CMNV globally at present, and there is no evidence of infection through the general consumption of cooked seafood.
The CDC will continue to monitor relevant international outbreaks, develop human specimen testing technologies and methods, and establish relevant sampling and testing conditions for risk monitoring and early warning.
According to the monitoring of the Animal and Plant Health Inspection and Quarantine Bureau of the Ministry of Agriculture, there have never been any CMNV outbreaks in shrimp farms in Taiwan.
The CDC's overall assessment is that the risk of domestic transmission is extremely low, but both agriculture and health authorities will continue to strengthen monitoring.
CMNV has been listed as an emerging infectious disease by the World Organisation for Animal Health, and infection cases have been reported in shrimp farms in China and Thailand.
The CDC urges travelers to China and Thailand to take special precautions against CMNV, including thoroughly cooking seafood, avoiding raw seafood for high-risk groups (such as those with chronic diseases), wearing gloves when handling raw seafood, avoiding direct contact with raw food if hands are open, and washing hands thoroughly with soap and water after handling to reduce the risk of infection by various pathogens.
Source:
Link: https://www.cdc.gov.tw/Bulletin/Detail/JAKoFRedyjAVo_zmdBsCfQ?typeid=9
____
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}
(...)
-- Avian influenza A(H9N2):
- Guangdong Province:
1) A three-year-old boy with onset on January 20, 2026.
- Guangxi Zhuang Autonomous Region:
2) A 63-year-old man with onset on February 5, 2026.
(...)
Source:
Link: https://www.chp.gov.hk/files/pdf/2026_avian_influenza_report_vol22_wk15.pdf
____
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
Clade 2.3.4.4b highly pathogenic avian influenza A(H5N1) viruses continue to expand geographically and across mammalian hosts, raising concern about pandemic potential. The degree and specificity of pre-existing immunity in humans are key determinants of this risk. We analyzed hemagglutinin (HA)- and neuraminidase (NA)-specific antibody responses in 300 sera collected from adults in New York City. While HA directed binding antibodies to clade 2.3.4.4b H5 were low and hemagglutination-inhibiting antibodies were absent, we detected widespread binding and functional NA antibodies against N1 neuraminidases from clade 2.3.4.4b H5N1 viruses. Neuraminidase inhibition (NI) titers were highest against North American D1.1 genotype N1 viruses and correlated strongly with neutralizing activity, whereas HA-binding antibodies did not. An additional N-linked glycosylation site, as found in the NA of a human D1.1 isolate from British Columbia, reduced susceptibility to NI antibodies. Antibodies titer to N5 from H5N5 were low to minimal. These findings indicate that population-level immunity to clade 2.3.4.4b H5 viruses is dominated by NA-directed antibodies, with important implications for pandemic risk assessment.
IMPORTANCE
Understanding how pre-existing human immunity shapes susceptibility to emerging influenza viruses is central to pandemic preparedness. Here, we determined that human sera contain widespread, functional antibodies targeting H5N1 neuraminidase, which correlate with virus neutralization, whereas HA-directed responses are limited. We further show that acquisition of an NA glycosylation site reduces antibody inhibition, highlighting a potential pathway for immune evasion. These results identify neuraminidase-specific immunity as a major immunological barrier to severe H5N1 disease in humans and emphasize the need to incorporate NA antigenicity into influenza surveillance, risk assessment, and next-generation vaccine design.
Source:
Link: https://journals.asm.org/doi/10.1128/mbio.00445-26
____
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.
Highlight
• HEV remains the leading cause of acute viral hepatitis in Europe
• Surveillance and diagnostics for HEV are heterogeneous across EU/EEA
• Zoonotic HEV circulates widely in pigs, wildlife and food chains
• Rat HEV expands the zoonotic spectrum and clinical burden in Europe
• ONWARD integrates One Health surveillance, research and capacity building
Abstract
Zoonotic hepeviruses, particularly hepatitis E virus (HEV, species Paslahepevirus balayani) represent a major yet underestimated public health challenge in Europe. Despite being the leading cause of acute viral hepatitis, surveillance, diagnostic practices and prevention strategies remain heterogeneous across EU/EEA countries, limiting comparability and hindering accurate burden estimates. Underdiagnosis is further compounded by extrahepatic manifestations and the growing impact of chronic HEV infection in immunocompromised patients. At the human–animal–environment interface, zoonotic HEV circulates widely in domestic pigs, wildlife and food products, while coordinated surveillance and control measures remain inconsistently implemented. The recent recognition of ratHEV (species Rocahepevirus ratti) as a cause of acute and chronic hepatitis in Europe further expands the spectrum of zoonotic hepevirus infections and underscores the need for integrated One Health approaches. To address these challenges, the One Health Zoonotic Hepevirus Network (ONWARD; COST Action CA24140) was launched in 2025 as a pan-European, multidisciplinary collaboration uniting experts across human, veterinary, food safety and environmental health sectors. ONWARD aims to harmonise diagnostic tools, strengthen clinical research, integrate multisectoral surveillance, promote capacity building and support evidence-based policy development. By fostering coordination with European stakeholders ONWARD provides a structured framework to strengthen preparedness, surveillance and response to zoonotic hepevirus threats across Europe.
Source:
Link: https://www.sciencedirect.com/science/article/pii/S1386653226000338?dgcid=rss_sd_all
____
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.
