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

 

Abstract

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

Competing Interest Statement

The authors have declared no competing interest.

Funder Information Declared

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

European Union Horizon 2023 RIA project LEAPS, 101094685

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

Fonds National de la Recherche Scientifique, F.4515.22

European Union Horizon 2020 project MOOD, 874850

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

Source: 

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

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#Taiwan #CDC issued a #statement regarding journal research on transmission of viruses from farmed #shrimp in #China to #humans (Apr. 18 '26)

 

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

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#Population #immunity to clade 2.3.4.4b #H5N1 is dominated by anti - #neuraminidase #antibodies

 

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

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#Genomic similarity to quantitatively evaluate the #reassortment #potential of #H7N9 with other subtypes of avian #influenza viruses

 

Abstract

Introduction: 

The H7N9 influenza virus poses a significant public health threat due to its potential for reassortment and cross-species transmission. This study aims to systematically evaluate the genomic similarity between H7N9 and other influenza A subtypes to identify strains with high reassortment potential and characterize their spatiotemporal and host distribution patterns.

Methods: 

We analyzed nearly 4,000 H7N9 sequences from GISAID and NCBI, alongside representative sequences of other influenza A subtypes. Open reading frames were extracted, and a genomic similarity index was constructed using Euclidean distance, dot product, and cosine similarity measures, with weights optimized via principal component analysis. The index was applied to quantify inter-subtype similarity and predict reassortment-prone strains.

Results: 

High sequence similarity was observed between H7N9 and cognate subtypes (e.g., H7N3, H15N9), with H7N3 exhibiting the highest similarity index (1.00). Validation using known reassortant strains, such as A/Yixing/805/2022 (H3N2), confirmed that strains with high reassortment potential showed significantly elevated similarity scores across all gene segments (p< 0.001). High-similarity outliers analysis identified 581 spillover events, temporally concentrated during 2014–2017, and spatially clustered in regions like the United States, Europe, and Hong Kong. Host analysis highlighted birds—especially chickens, ducks, and turkeys—as key reservoirs for reassortment.

Discussion: 

The genomic similarity index effectively identifies influenza A subtypes with high reassortment potential, supported by retrospective validation and spatiotemporal congruence with documented outbreaks. The concentration of high-similarity strains in specific hosts and regions underscores the role of ecological factors in viral evolution. These findings provide a predictive framework for monitoring emergent reassortants and inform targeted surveillance strategies.

Source: 

Link: https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2026.1777911/full

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Avian #Influenza #H9N2 - #Italy (#WHO, D.O.N., April 10 2026)

 

Situation at a glance

-- On 21 March 2026, the National International Health Regulations (IHR) Focal Point for Italy notified the World Health Organization (WHO) of the identification of a human case of avian influenza A(H9) in an adult male returning from Senegal. 

- Next generation sequencing confirmed Influenza A(H9N2). 

- According to epidemiological investigations, the patient had no known history of exposure to poultry or any person with similar symptoms prior to the onset of symptoms. 

- Authorities in Italy have implemented a series of measures aimed at monitoring, preventing and controlling the situation. 

- According to the IHR (2005), a human infection caused by a novel influenza A virus subtype is an event that has the potential for high public health impact and must be notified to the WHO. 

- This is the first imported human case of avian Influenza A(H9N2) reported in the European Region. 

- Based on currently available information, WHO assesses the current risk to the general population posed by A(H9N2) viruses as low but continues to monitor these viruses and the situation globally.

Description of the situation

-- On 21 March 2026, the National IHR Focal Point for Italy notified WHO of the identification of a human case of avian influenza A(H9) in an adult male.

-- The patient had been in Senegal for more than six months and traveled to Italy in mid-March. Upon arrival, he visited the emergency department with a fever and a persistent cough.

-- On 16 March, a bronchoalveolar lavage specimen was collected, which showed a positive Mycobacterium tuberculosis result, as well as detection of un-subtypeable influenza A virus. The patient was placed in a negative-pressure isolation room with airborne precautions. He was treated with antitubercular medication and antiviral oseltamivir. By 9 April, his condition was stable and improving.

-- On 20 March, a regional reference laboratory identified the A(H9) subtype, and on 21 March, next-generation sequencing confirmed influenza A(H9N2). 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. They also received oseltamivir as a preventive measure. 

Epidemiology

-- Animal influenza viruses normally circulate in animals but can also infect people. Infections in humans have primarily been acquired through direct contact with infected animals or through indirect contact with contaminated environments. Depending on the original host, influenza A viruses can be classified as avian influenza, swine influenza, or other types of animal influenza viruses.

-- Avian influenza virus infections in humans may cause diseases ranging from mild upper respiratory tract infection to more severe diseases and can be fatal. Conjunctivitis, gastrointestinal symptoms, encephalitis and encephalopathy have also been reported.

-- Laboratory tests are required to diagnose human infection with influenza. WHO periodically updates technical guidance protocols for the detection of zoonotic influenza using molecular methods. 

-- Human infections with influenza A(H9) viruses have been reported from countries in Africa and Asia, where these viruses are also detected in poultry. The majority of cases of human avian influenza A(H9N2) infection have been reported from China. This is the first imported human case of avian Influenza A(H9N2) virus infection reported in the European Region. 

Public health response

-- Contact tracing procedures have been initiated, and relevant authorities in Italy, as well as internationally (National IHR Focal Point for Senegal, WHO, and European Centre for Disease Prevention and Control (ECDC)) have been informed through IHR channels. Once avian influenza was suspected, the response moved quickly from hospital-level management to regional laboratory confirmation and national coordination. Additionally, the regional surveillance system was notified, integrated within the One Health avian influenza reporting framework.

WHO risk assessment

-- Most reported human cases of A(H9N2) virus infection have been linked to exposure to infected poultry or contaminated environments, with the majority of cases experiencing mild clinical illness. Sporadic human cases following exposure to infected birds or contaminated environments can be expected since the virus remains enzootic in poultry populations. Avian influenza A(H9N2) viruses have been detected in poultry and environmental samples collected at live bird markets in Senegal and authorities in the country reported a human case of infection with an A(H9N2) virus in 2020.

-- Current epidemiological and virological evidence indicates that none of the characterized influenza A(H9N2) viruses thus far have acquired the ability for sustained transmission among humans. Thus, the likelihood of sustained human-to-human spread is low at this time. Infected individuals traveling internationally from affected areas may be identified in another country during or after arrival. However, if this were to occur, further community-level spread is considered unlikely. The risk assessment would be revisited if and when further epidemiological and virological information becomes available.

WHO advice

-- This case does not change the current WHO recommendations on public health measures and surveillance of influenza.

-- The public should avoid contact with high-risk environments such as live animal markets/farms or surfaces that might be contaminated by poultry feces. Respiratory protection is highly recommended for those handling live or dead (including slaughtering) poultry in occupational or backyard-farming settings. Good hand hygiene, i.e. frequent washing of hands or the use of alcohol-based hand sanitizer is recommended. WHO does not recommend any specific additional measures for travelers.

-- Under Article 6 of the IHR, all human infections caused by a new subtype of influenza virus are notifiable. The case definition for notification of human influenza infection caused by a new subtype under the IHR is provided here. State Parties to the IHR are required to immediately notify WHO of any laboratory-confirmed case of a human infection caused by such an influenza A virus.

-- WHO advises against the application of any travel or trade restrictions based on the current information available on this event. 

Further information

-- WHO fact sheet on Influenza (avian and other zoonotic): https://www.who.int/news-room/fact-sheets/detail/influenza-(avian-and-other-zoonotic)

-- WHO Global influenza programme, human-animal interface: https://www.who.int/teams/global-influenza-programme/avian-influenza

-- WHO Monthly Risk Assessment Summary: Influenza at the human-animal interface: https://www.who.int/teams/global-influenza-programme/avian-influenza/monthly-risk-assessment-summary

-- Protocol to investigate non-seasonal influenza and other emerging acute respiratory diseases: https://www.who.int/publications-detail-redirect/WHO-WHE-IHM-GIP-2018.2

-- World Health Organization. Public health resource pack for countries experiencing outbreaks of influenza in animals: revised guidance: https://www.who.int/publications/i/item/9789240076884

-- Implementing the integrated sentinel surveillance of influenza and other respiratory viruses of epidemic and pandemic potential by the Global Influenza Surveillance and Response System: https://www.who.int/publications/i/item/9789240101432

-- Case definitions for the four diseases requiring notification in all circumstances under the International Health Regulations (2005): https://www.who.int/publications/m/item/case-definitions-for-the-four-diseases-requiring-notification-to-who-in-all-circumstances-under-the-ihr-(2005)

-- Mosaic Respiratory Surveillance Framework: https://www.who.int/initiatives/mosaic-respiratory-surveillance-framework/

-- Practical interim guidance to reduce the risk of infection in people exposed to avian influenza viruses: https://www.who.int/publications/i/item/B09116

-- Antigenic and molecular characterization of low pathogenic avian influenza A(H9N2) viruses in sub-Saharan Africa from 2017 through 2019: https://hal.inrae.fr/hal-03213105v1

-- Genetic and Molecular Characterization of Avian Influenza A(H9N2) Viruses from Live Bird Markets (LBM) in Senegal: https://doi.org/10.3390/v17010073

-- Genetic characterization of the first detected human case of low pathogenic avian influenza A/H9N2 in sub-Saharan Africa, Senegal: https://doi.org/10.1080/22221751.2020.1763858

-- ECDC. First human case of influenza A(H9N2) infection imported in the EU: https://www.ecdc.europa.eu/en/news-events/first-human-case-influenza-ah9n2-infection-imported-eu

-- Ministry of Health, Italy. Influenza A (H9N2) virus case identified in Lombardy. Routine surveillance and prevention procedures activated: https://www.salute.gov.it/new/it/comunicato-stampa/virus-influenzale-h9n2-identificato-caso-lombardia-attivate-le-ordinarie/

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Citable reference: World Health Organization (10 April 2026). Disease Outbreak News: Avian Influenza A(H9N2) in Italy. Available at: https://www/who.int/emergencies/disease-outbreak-news/item/2026-DON597

Source: 

Link: https://www.who.int/emergencies/disease-outbreak-news/item/2026-DON597

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#USA, Weekly #US #Influenza #Surveillance #Report: Key Updates for Week 13, ending April 4, 2026 (#CDC, summary)

 

(...)

Key Points

-- Seasonal influenza activity continues to decrease in most areas of the country. 

- Influenza A activity is low across all HHS regions while the amount of and trends in influenza B activity vary by region.

-- Influenza A(H3N2) viruses are the most frequently reported influenza viruses overall this season.

-- Among 2,166 influenza A(H3N2) viruses collected since September 28, 2025, that underwent additional genetic characterization at CDC, 92.8% belonged to subclade K.

-- The cumulative influenza-associated hospitalization rate overall in FluSurv-NET is the third highest since the 2010-2011 season. 

- Children younger than 18 years have the second highest cumulative hospitalization rate for that age group since the 2010-2011 season.

-- Twelve influenza-associated pediatric deaths occurring during the 2025-2026 season were reported to CDC this week, bringing the season total to 139 reported influenza-associated pediatric deaths.

-- Among children who were eligible for influenza vaccination and with known vaccination status, approximately 85% of reported pediatric deaths this season have occurred in children who were not fully vaccinated against influenza.

-- CDC's in-season severity assessment framework classified the season as moderate across all ages. 

- CDC also assesses severity by three age groups: pediatric (0-17 years), adult (18-64 years), and older adults (≥65 years). 

- At this point in the season, the pediatric age group is classified as having high severity, while both the adult and older adult age groups are classified as having moderate severity. 

- These assessments are conducted each week during the season, and the season's severity assessment can change if activity should increase again.

-- CDC estimates that there have been at least 31 million illnesses, 370,000 hospitalizations, and 23,000 deaths from flu so far this season.

-- Influenza (flu) vaccination has been shown to reduce the risk of flu and its potentially serious complications. 

- There is still time to get vaccinated against flu this season. 

- Approximately 135 million doses of influenza vaccine have been distributed in the United States this season.

-- There are prescription flu antiviral drugs that can treat flu illness; those should be started as early as possible and are especially important for patients at higher risk for flu-related complications.1

-- Influenza viruses are among several viruses contributing to respiratory disease activity. CDC provides updated, integrated information about COVID-19, flu, and respiratory syncytial virus (RSV) activity on a weekly basis.

-- No new avian influenza A(H5) infections were reported to CDC this week. To date, person-to-person transmission of influenza A(H5) viruses has not been identified in the United States.

(...)

Source: 

Link: https://www.cdc.gov/fluview/surveillance/2026-week-13.html

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#Genetic and #biological characterization of a #duck-origin clade 2.3.4.4b #H5N6 avian #influenza virus reveals partial #mammalian #adaptation

 

Highlights

• Duck-origin H5N6 virus A/Duck/Jiangsu/628/2022 shares high homology with the human strain A/Yangzhou/125/2022.

• The 628 strain shows mammalian adaptation markers: HA mutations enhance human receptors affinity and NA mutations reduce sensitivity to neuraminidase inhibitors.

• Limited airborne transmission but detectable droplet-mediated spread suggests increased mammalian transmission risk.

Abstract

Clade 2.3.4.4b H5Nx highly pathogenic avian influenza viruses (HPAIVs) have caused extensive outbreaks in poultry worldwide. H5 HPAIVs have caused sporadic but severe human infections in China, representing a persistent zoonotic threat. Here, we identified a duck-origin H5N6 HPAIV (A/Duck/Jiangsu/628/2022) through routine surveillance and assessed its biological characteristics and mammalian pathogenesis. Phylogenetic analysis revealed > 98% nucleotide identity between strain 628 and the concurrent human H5N6 strain A/Yangzhou/125/2022. Molecular characterization identified multiple mammalian adaptation markers: hemagglutinin substitutions (S137A, T160A, T192I) associated with enhanced human receptor binding; neuraminidase mutations (I117T, D198N) linked to reduced neuraminidase inhibitor susceptibility; and polymerase complex changes (PB1-D622G, PA-K142Q) conferring increased mammalian cell replication. In vitro studies demonstrated that 628 virus replicated more efficiently in mammalian than in avian cells and exhibited dual receptor-binding specificity. Mouse pathogenicity assays revealed moderate virulence with progressive lung pathology. Critically, transmission experiments confirmed both direct contact and airborne transmission capabilities of 628 in guinea pigs. These findings demonstrate that circulating H5N6 viruses have acquired partial mammalian adaptation while retaining avian fitness, significantly elevating pandemic potential. Enhanced surveillance of wild bird populations, poultry farms, and live poultry markets is urgently needed to develop effective prevention and control strategies.

Source: 

Link: https://www.sciencedirect.com/science/article/abs/pii/S037811352600146X?via%3Dihub

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#Surveillance and cross-species #transmission #assessment of #H3NX avian #influenza viruses isolated in #Guangdong province, #China from 2023 to 2025

 

Abstract

Continued influenza surveillance remains important, especially given that the emergence of novel subtypes or reassorted influenza viruses with pandemic potential continues to be a worldwide threat. In particular, virus circulating in birds can facilitate interspecies transmission to humans. In this study, we conducted systematic surveillance of H3 subtype avian influenza virus (AIVs) in domestic poultry and wild birds throughout Guangdong Province from 2023 to 2025. A total of 21 strains of H3 subtype AIVs were isolated, and phylogenetic analyses and risk assessment of their internal gene segments revealed genetic evidence of reassortment events, indicating a close genetic relationship with highly pathogenic avian influenza viruses (HPAIVs). ZJ1722, ZJ1542 and SZ837 showed dual-receptor binding ability and robust replication in mammalian cells, which coincided with amino acid mutations in the HA protein associated with human receptor binding. Although the H3NX viruses isolated in this study failed to cause lethality in mice, they efficiently replicated in the nasal turbinate and lungs of mice without prior adaptation. This study highlights the paramount importance of sustained, subtype-specific surveillance targeting H3NX avian influenza viruses coupled with timely risk characterization and assessment. Proactive containment of H3NX avian influenza virus (AIV) transmission has vital implications for safeguarding the sustainability of the poultry industry and protecting global human public health, given the inherent zoonotic potential and evolutionary plasticity of this H3 subtype, which could drive future spillover events.

Source: 

Link: https://www.sciencedirect.com/science/article/pii/S0032579126004918?via%3Dihub

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#Taiwan: First locally acquired #human case of novel avian #H7 #influenza virus has been detected (MoH, edited)

 

The Taiwan Centers for Disease Control (CDC) announced today (March 2nd) the first locally transmitted case of novel H7 subtype avian influenza in Taiwan. 

The patient is a man in his 70s from central Taiwan who works in poultry farming and has a history of chronic illness. 

He developed symptoms of runny nose, cough, and body aches on March 20th and sought medical attention at a hospital on March 22nd due to fever. 

He was admitted to the hospital on the same day. 

Imaging examination revealed pneumonia. 

Based on clinical symptoms, test results, and the patient's contact history, the doctor reported the case as a novel H7 avian influenza and administered antiviral medication. 

Further testing and gene sequencing by the CDC confirmed the virus as H7 subtype avian influenza. 

Sequence analysis showed that this H7 belongs to the Eurasian lineage and is similar to the H7 subtype avian influenza viruses monitored in wild birds (mainly ducks and anadidae) in Taiwan over the years. 

However, it is different from the H7N9 subtype avian influenza virus that circulated in mainland China from 2013 to 2019, and is a low-pathogenic avian influenza virus. 

This morning, the CDC convened a meeting with agricultural authorities and relevant medical and veterinary experts to discuss the case and, based on the test results, confirmed it as a case of novel H7 avian influenza in humans. 

The patient's condition has improved and they are continuing isolation and treatment. 

The Centers for Disease Control (CDC) stated that after the first locally transmitted case of H7 subtype novel influenza A was detected in Taiwan, health and agricultural authorities immediately launched a joint epidemic prevention operation to carry out relevant investigations and prevention measures. 

Health authorities, with the assistance of epidemiologists and the Health Bureau, conducted on-site epidemiological investigations at the patient's residence, poultry farm, and hospital. 

Currently, 33 close contacts are under health monitoring and management, and 3 have been given preventative medication based on risk assessment. 

Tests were conducted on 6 family members, all of whom tested negative. 

Agricultural authorities immediately implemented movement restrictions at the poultry farm, and animal testing results were negative for avian influenza virus. 

To clarify the source of infection, today's expert meeting resolved to request the farm to expand testing at nearby poultry farms and to cooperate with wild bird associations to collect droppings from surrounding wild birds. 

Furthermore, the CDC will continue to cooperate with the farm to obtain the gene sequence of the H7 virus detected in Taiwan for further comparison. 

Health and agricultural authorities will continue to strengthen surveillance of humans and animals, including respiratory viruses and influenza/novel coronavirus pneumonia surveillance in medical institutions, active surveillance of poultry farms and migratory birds, and will cooperate with farmers to promote personal protective measures for poultry farmers and public health education. 

They have also contacted duck farming associations to distribute 40,000-50,000 masks free of charge to duck farmers. 

The Centers for Disease Control (CDC) pointed out that, based on current epidemiological investigations and test results, the genetic analysis of this case shows a low-pathogenic avian influenza virus, without any mutations increasing the risk of avian-to-human transmission, and it remains a common avian virus. 

The initial assessment is that this case is an isolated incident. 

Considering the patient's improved condition after treatment, the lack of mutations increasing the risk of avian-to-human transmission in the preliminary genetic analysis, the negative test results at the poultry farm, and the absence of any other family members showing symptoms after the patient's onset, the risk is assessed as controllable, and there is no immediate risk of the outbreak expanding. 

However, to understand the potential risks of this case, they will continue to track the symptoms and test results of contacts, further analyze the virus and trace possible sources of infection, and have activated a joint working group on the risk assessment of zoonotic infectious diseases between agriculture and health authorities to conduct a comprehensive risk assessment. 

The Taiwan Centers for Disease Control (CDC) will notify the World Health Organization (WHO) today through the IHR contact window in accordance with the International Health Regulations (IHR).

According to surveillance data, since the novel influenza A virus was classified as a Category 5 notifiable infectious disease in Taiwan in 2014, a total of 5 sporadic cases have been reported. Besides this case, the others were reported in 2017 (H7N9, imported from outside China), 2021 (H1N2v), 2022 (H1N2v), and 2023 (H1N2v). In addition, there were 4 confirmed cases of H7N9 imported from outside China in 2013-2014; none of the contacts were infected.

The CDC explained that the H7N9 sequence in today's reported case is only closely related to one other human case, H7N4, reported in Jiangsu, China in 2018. The case involves a 68-year-old woman with a history of coronary heart disease and hypertension. She developed symptoms such as cough, weakness, and muscle aches on December 25, 2017, and was hospitalized for pneumonia on January 1, 2018, and discharged on January 22 after recovery. Prior to the onset of illness, the patient had contact with live poultry. Her close contacts did not develop any suspected symptoms during the observation period. The virus remains avian and has not shown resistance to existing antiviral drugs.

The Centers for Disease Control (CDC) reminds workers involved in poultry and livestock farming to implement self-protection measures during operations and to conduct thorough disinfection after work to reduce the risk of infection with the novel influenza A. If symptoms of acute respiratory infection or conjunctivitis appear, seek medical attention immediately and proactively inform healthcare professionals of your occupational history of contact with animals to facilitate early diagnosis. The public is advised to implement the "5 Dos and 6 Don'ts" epidemic prevention principles in daily life:

"5 Dos": Cook meat and eggs thoroughly with soap; wash hands thoroughly with soap; if symptoms appear, wear a mask, seek medical attention immediately, and inform the doctor of your occupation and contact history; those who have long-term contact with poultry and livestock should get vaccinated against influenza; maintain a balanced diet and exercise appropriately.

"6 Don'ts": Don't eat raw poultry, eggs, or poultry products; don't smuggle or buy meat of unknown origin; don't touch or feed poultry and livestock; don't release or discard poultry and livestock indiscriminately; don't mix poultry and livestock with other poultry and livestock; and don't go to places with poor air circulation or crowded places.

For related information, please visit the Taiwan Centers for Disease Control website (https://www.cdc.gov.tw/) or call the toll-free epidemic prevention hotline 1922 (or 0800-001922).

Source: 

Link: https://www.cdc.gov.tw/Bulletin/Detail/bZE85LXA9ZGdCvEJKZe6Cg?typeid=9

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#Mpox - cMulti-country external #situation #report no. 64, published 26 March 2026 (#WHO, summary)

 

{Excerpt}

Highlights

• Transmission of mpox continues mostly within sexual networks, affecting both women and men, followed by household transmission, and in some historically endemic areas, affecting all age groups. 

- All clades of monkeypox virus (MPXV) continue to circulate. 

- Unless mpox outbreaks are rapidly contained and human-to-human transmission is interrupted, there is a risk of sustained community transmission in all settings. 

• In February 2026, 46 countries across all WHO regions reported a total of 1184 confirmed mpox cases, including four deaths (case fatality ratio [CFR] 0.3%). 

- Of these cases, 58.6% were reported in the WHO African Region. 

• Four WHO regions – the Region of the Americas and the African, South-East Asian and Western Pacific regions – reported a decline in confirmed cases in February, compared to January 2026, while the European Region reported an increase in confirmed cases. 

- The Eastern Mediterranean Region reported the same monthly case count in January and February 2026.

• Seventeen countries in Africa reported active transmission of mpox in the last six weeks (1 February – 15 March 2026), with 907 confirmed cases, including seven deaths (CFR 0.8%). 

- Countries reporting the highest number of cases in this period are Madagascar, the Democratic Republic of the Congo, Kenya, Burundi, and Liberia. 

• Three countries, Argentina, Austria, and the Central African Republic, have reported mpox due to clade Ib MPXV for the first time. 

• Outside Africa, community transmission of clade Ib MPXV continues in the WHO European Region, with Austria, Belgium, Portugal, Spain, and the United Kingdom of Great Britain and Northern Ireland reporting community transmission, including in sexual networks of men who have sex with men.  

• This report provides an update on mpox outbreak transmission dynamics across different clades and settings. 

• On 7 April 2026, World Health Day, WHO will join a One Health summit convened by the Government of France. 

- The Summit will foster international and interdisciplinary dialogue to highlight the interdependence of human, animal, plant and ecosystem health, and the need for coordinated, science-based approaches to address shared health threats, including for emergency response. 

(...)

Source: 

Link: https://www.who.int/publications/m/item/multi-country-outbreak-of-mpox--external-situation-report--64---26-march-2026

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Rapid #risk #assessment, acute event of potential public health concern: #Diphtheria, #Africa Region (#WHO, March 20 '26)

{Summary)

Risk statement

-- This WHO Rapid Risk Assessment (RRA, v2) aims to assess the risk of diphtheria at the regional level, considering the public health impact, the risk of geographical spread and the risk of insufficient control capacities with available resources. 

-- Diphtheria is a major public health problem in the WHO African Region (AFR) despite significant efforts on immunization in the past decades (e.g. introduction of DTP vaccine in the Expanded Program on Immunisation in 1974). 

-- Between 2000 and 2024, 75 789 diphtheria suspected cases were reported across the Region with an average 3 500 cases per year.    

-- Between the beginning of 2025 and as of 1 March 2026, over 29 000 suspected diphtheria cases with 1 420 deaths (CFR 4.9%) have been reported across these eight countries: Algeria, Chad, Guinea, Mali, Mauritania, Niger, Nigeria and South. 

-- This represents a 67% increase in the number of suspected cases (11 749 additional cases) and a 59.4% increase in the number of deaths (529 additional deaths) reported since the last WHO RRA (v1) conducted in October 2025, Nigeria continues to account for the majority of suspected cases (62.6%) and deaths (66%) in the Region. 

-- Of the 18 130 total confirmed cases (clinically compatible, laboratory-confirmed and epidemiologically linked) across the eight affected countries, 752 (4%) cases were recorded as laboratory-confirmed: Algeria (8), Chad (1), Guinea (48), Mali (66), Mauritania (12), Niger (313), Nigeria (211) and South Africa (93).     

-- Case data trends from 2026 have been difficult to interpret, with extremely delayed case reporting from countries (both to the national and regional levels), and instances of under-reporting also being notified, particularly from humanitarian settings. 

-- However, a lower number of cases are being consistently reported than earlier in the outbreak and thus it appears that new cases continue to decline or plateau, as seen in half of the affected countries (Chad, Mali, Mauritania, and Nigeria).    

-- Since the first WHO RRA (v1) conducted in October 2025, the regional CFR remains around 5%. 

-- While Guinea continues to report among the highest CFRs in the region at 19%, South Africa’s CFR has increased since the last WHO RRA (v1) to 19%.  

-- Children aged 5–14 yrs (57%) and females (63%) are the most affected; where information is available on the vaccination status of cases, most cases are unvaccinated, under-vaccinated, or with unknown vaccination status.   

-- While the overall risk was previously assessed as “HIGH” at the regional level in October 2025, it is now considered “MODERATE” due to:  

• Overall declining trend in number of weekly cases regionally, with country-specific trends also declining in half of the affected countries (Chad, Mali, Mauritania and Nigeria), and only sporadic cases reported from South Africa. 

• Strengthened coordination of public health response through the activation of an Incident Management System (IMS) in most of the affected countries. A joint Regional Office for Africa (AFRO) and WHO headquarters (HQ) IMS structure was activated to support the regional coordination of the response, with high-level ministerial commitment to controlling the outbreaks in the affected countries.  

• Implementation of immunization activities as part of the outbreak response in most of the affected countries. 

• Strengthening of surveillance, case management, community sensitization, through capacity building activities, and the provision of diphtheria antitoxin (DAT), antibiotics, laboratory supplies, etc.  

-- Nonetheless, some challenges continue to prevent the effective containment of these outbreaks:  

• The complex humanitarian situation in many of the affected countries continues to contribute to poor access to immunization and healthcare services for internally displaced persons (IDPs), nomads, miners, and migrants. Unsanitary living conditions (in displacement camps) are also favouring the transmission of diphtheria. These increase the exposure risk of vulnerable groups (particularly women and children) to diseases.   

• Limited laboratory confirmation due to lack of reagents, sample transportation challenges and limited available of laboratory capacity.  

• In most of the affected countries, the annual coverage for routine diphtheria vaccination remains below the national targets thereby contributing to the resurgence of cases and outbreaks.  

• Global scarcity of DAT for the treatment of affected persons. 

• High internal and cross-border movements of susceptible individuals (unvaccinated or not fully vaccinated). 

• Persistent funding challenges across most affected countries exacerbated by the current challenging international funding landscape.  

-- The overall risk at the global level remains ‘’LOW’’ due to: 

- The global risk of diphtheria outbreaks from the ongoing multi-country diphtheria outbreak in the African region is assessed as low, given the existence of routine immunization programs in most countries. 

- Nonetheless, the risk posed by international travel of susceptible populations from the WHO African Region cannot be overlooked, highlighting the need to strengthen risk communication, demand generation and reactive immunisation, as well as the need for enhanced data sharing and surveillance globally. 

(...)

Source: 

Link: https://www.who.int/publications/m/item/who-rapid-risk-assessment---diphtheria--african-region-v.2

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Rapid #Risk #Assessment, Acute Event of Potential Public Health Concern: #Nipah Virus #Infection - Global (#WHO, Mar. 6 '26, summary)

 

{Summary}

Risk Statement  

-- This Rapid Risk Assessment (RRA) evaluates the global public health risk posed by Nipah virus (NiV), considering the distinct epidemiological profiles of 

- i) enzootic countries, where recurrent zoonotic spillover and limited human‑to‑human transmission continue to occur, and 

- ii) non‑enzootic regions, where the risk remains primarily associated with infected travellers or importation of infected livestock. 

-- The assessment considers the ecological and seasonal drivers of spillover, the constrained efficiency of human‑to‑human transmission, and the capacity of health and community systems to detect, confirm, and rapidly contain outbreaks. 

-- Given that NiV has not demonstrated sustained transmission beyond outbreak settings and no human cases have ever been reported outside Asia, the global risk is largely determined by localized outbreaks in endemic areas and the very low likelihood of onward transmission following importation. 

-- NiV activity remains geographically limited, with human cases occurring primarily in the South-East Asia Region with limited outbreaks in the Western Pacific Region. 

-- The epidemiological profile of NiV is characterized by low frequency, localized outbreaks, occurring predominantly in Bangladesh and India, with additional historical events reported in Malaysia, Singapore, and the Philippines. 

-- Bangladesh has reported sporadic cases almost annually since 2001, largely associated with consumption of raw date palm sap, following a well‑defined seasonal pattern between December and April. 

-- India reported its first outbreak in 2001 and has documented near-annual cases in Kerala since 2018 with sporadic cases reported in West Bengal. 

-- In 2025, eight laboratory‑confirmed cases were detected across Bangladesh (four) and India (four). 

-- As of March 2026, three sporadic cases have been reported in the two countries, two in India and one in Bangladesh. 

-- Malaysia (1998–1999), Singapore (1999), and the Philippines (2014) experienced outbreaks previously but have not reported any additional NiV events recently. 

-- Although NiV has a high case‑fatality ratio (40–75%), transmission remains limited in scale, typically arising from isolated spillover events linked to fruit bats, contaminated fruits or fruit products, or occasionally infected livestock. 

-- Human‑to‑human transmission has been documented, particularly in Bangladesh and India. However, sustained community transmission or multi‑country spread has never been observed. 

KEY RISK FACTORS 

{1.} Risk to Enzootic Countries  

• Sporadic zoonotic spillover events occur due to contact with infected bats or consumption of contaminated fruits or fruit products.  

• Serological evidence of NiV circulation beyond affected areas in Bangladesh and India (Kerala and West Bengal), suggest that spillover could potentially occur in other areas where infected bats are present. 

• Human‑to‑human transmission, although documented, is limited to close contacts and has not resulted in widespread community transmission. 

• The case‑fatality ratio is high; however, the total number of reported cases remains low. 

• Health care settings may amplify transmission when infection prevention and control (IPC) measures are insufficient.  

• Spillover from other susceptible animal hosts (pigs, horses) cannot be ruled out, nor the risk of importation through infected livestock, though probably very low.  

{2.} Risk to Non‑Enzootic Regions (reservoirs may be present; no human cases to date) 

• Risk is primarily associated with an infected traveller. 

• No human NiV transmission has ever been reported outside affected Asian countries. 

• In settings without established animal reservoirs or intermediate hosts, onward transmission following importation is unlikely and would require close, prolonged contact. 

• Historical spread via movement of infected animals (e.g., pigs exported from Malaysia to Singapore in 1999) demonstrates that animal trade–related spillover is possible, however current evidence suggests that the risk under present animal‑health and trade practices is likely very low.  

{3.} Risk to Countries Without Known Bat Reservoirs (reservoirs absent; no human cases) 

• Importation via travellers (and, exceptionally, livestock) may occur and while secondary transmission is possible it is unlikely, given the absence of established animal reservoirs and the need for close contact for human‑to‑human spread. 

{4.} Risk to Travellers 

• Travellers to affected areas face a very low but non‑zero risk, particularly if they have direct exposure to fruit bats, consume contaminated food products, or come into contact with other infected animals, including pigs or horses. 

• Returning infected travellers pose a limited risk of onward transmission due to low NiV transmissibility. 

{5.} Risk Determinants 

• Ecological presence of Pteropodidae bats in enzootic countries.  

• Presence of potential intermediary hosts that could transmit to humans (e.g., pigs, horses).  

• Cultural and dietary practices (e.g., consumption of raw date palm sap). 

• Exposure in health care settings with inadequate IPC measures. 

• Limited awareness among communities and health workers. 

• Close, unprotected contact with sick/deceased individuals, including local practice traditions. 

{6.} Response Capacity 

• Countries with recurring outbreaks have strengthened their surveillance systems, diagnostics, and clinical management capacity. 

• No licensed vaccines or specific antiviral treatments are currently available; however, several vaccine and therapeutics candidates are in development, supported by CEPI and WHO‑aligned research priorities.  

• Rapid case isolation and contact tracing remain effective measures in preventing wider spread. 

{7.} Confidence in Available Information 

-- Overall confidence is moderate, due to: 

• Under‑detection of sporadic spillover events in rural areas. 

• Ongoing uncertainty about the full geographic distribution of bat reservoirs and potential intermediate hosts.  

-- Based on current evidence, characterized by rare outbreaks, limited human‑to‑human transmission, no sustained global spread, and improving response capacity, the overall global public health risk posed by NiV is assessed as Low with a Moderate level of confidence in the available information.  

-- This rapid risk assessment will be updated as new epidemiological, clinical, or virological information becomes available. 

(...)

Source: 

Link: https://www.who.int/publications/m/item/who-rapid-risk-assessment---nipah-virus---global---version-1

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Fatal #human #H3N8 #influenza virus has a moderate #pandemic #risk

 

Abstract

In China, low pathogenic avian influenza (LPAI) H3N8 virus is widespread among chickens and has recently caused three zoonotic infections, with the last one in 2023 being fatal. Here we evaluated the relative pandemic risk of this 2023 zoonotic H3N8 influenza virus, utilizing our previously published decision tree. Serological analysis indicated that a large proportion of the human population does not have any cross-neutralizing antibodies against this H3N8 strain. LPAI H3N8 displayed a dual affinity for α2–3 and α2–6 sialic acids and replicated efficiently in human bronchial epithelial cells. Furthermore, we observed H3N8 transmission via direct contact but not aerosols to ferrets with pre-existing H3N2 immunity. Although pre-existing H3N2 immunity resulted in a shortened disease course in ferrets, it did not reduce disease severity or replication in the respiratory tract. This study suggests that this zoonotic H3N8 strain has moderate pandemic potential and emphasizes the continued need for avian influenza surveillance.

Author summary

Low pathogenic avian influenza (LPAI) viruses circulate widely amongst birds and are a major public health concern for their ability to cross over to other species, including humans. Here we characterize the pandemic potential of an H3N8 LPAI virus that caused a lethal human infection. While this strain was only able to transmit by direct contact, we found that it did exhibit some human adaptations, and pre-existing immunity did not reduce replication or pathogenesis, suggesting that it is a moderate pandemic risk and needs to be monitored given the potential public health threat.

Source: 

Link: https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1013586

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#Mpox Multi-country external #situation #report no. 63, published 24 February 2026 (#WHO, summary)

 

Highlights   

• Transmission of mpox continues in sexual networks, affecting both women and men, and in some historically endemic areas. 

- All clades of monkeypox virus (MPXV) continue to circulate. 

- Unless mpox outbreaks are rapidly contained and human-to-human transmission is interrupted, there is a risk of sustained community transmission. 

• In January 2026, 50 countries across all WHO regions reported a total of 1334 new confirmed mpox cases, including three deaths (case fatality ratio [CFR] 0.2%). 

- Of these cases, 66% were reported in the African Region. 

• Four regions observed a decline in confirmed cases in January, compared to December 2025, while the European Region reported an increase in confirmed cases.

• Twenty countries in Africa reported active transmission of mpox in the last six weeks (5 January – 15 February 2026), with 1142 confirmed cases, including four deaths (CFR 0.4%). 

- Countries reporting the highest number of cases in this period are the Democratic Republic of the Congo, Guinea, Madagascar, Liberia and Ghana. 

• One country, Comoros, and one territory, La Réunion (Overseas Department of France), have reported mpox due to clade Ib MPXV for the first time.   

• Outside Africa, reports of community transmission of clade Ib MPXV continue in France, Portugal and Spain, including in sexual networks of men who have sex with men.  

• WHO conducted a global mpox rapid risk assessment in February 2026; the overall global public health risk associated with the mpox multi-country outbreak was assessed as moderate. 

• India has reported a case of mpox with the clade Ib /IIb recombinant MPXV. 

- The strain sequenced is closely related to the first clade Ib / IIb recombinant strain reported by the United Kingdom of Great Britain and Northern Ireland in December 2025. 

- As both cases are travel-related, these case reports suggest wider transmission of the recombinant strain, implicating four countries in three WHO regions. 

(...)

Source: 

Link: https://www.who.int/publications/m/item/multi-country-outbreak-of-mpox--external-situation-report--63---24-february-2026

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#MPOX, Multi-Country: Rapid #risk #assessment, 7 February 2026, v6 (#WHO, Feb. 18 '26)

 

{Excerpt}

Overall Global Risk Statement  

-- This global rapid risk assessment (RRA) aims to assess the current public health risk associated with the 2024 upsurge of mpox in in Africa, in the context of the continuing global reporting of mpox cases in other regions since 2022, with a focus on updates since the previous RRA in September 2025.    

Global overview 

-- As of 28 January 2026, the monkeypox virus (MPXV) continues to spread globally, causing both localized and extended mpox outbreaks driven by various MPXV clades (Ia, Ib, IIa, and IIb) in diverse settings. 

-- Furthermore, recombination of MPXV clades has been documented, with two cases of a recombinant clade Ib/IIb MPXV strain reported in recent months.  

-- Globally, from 1 January 2022 to 31 December 2025 (latest global data available), 143 countries and territories across all WHO regions have reported 177 848 confirmed cases, including 477 deaths (case fatality ratio [CFR] – 0.3%). 

-- This marks an increase of five additional reporting countries (Kuwait, Mali, Madagascar, Namibia and Senegal), along with an additional 19 423 confirmed cases and 78 deaths since the last RRA in September 2025. 

-- Since the last RRA, an average of 616 new confirmed mpox cases per week have been reported across all affected countries.

-- In addition, in January 2026, the Comoros and the French departments of Mayotte and la Réunion have reported cases linked to travel to Madagascar.  

-- Previous versions of this RRA have categorized risk based on MPXV clade. However, in absence of substantial data suggesting differences in the mode of transmission between different MPXV clades, and with relatively limited data suggesting higher case fatality for clade Ia MPXV compared to other clades, this version of the RRA assesses the risk for three population groups:

- global risk for individuals with multiple sexual partners, 

- local risk for children in mpox historically endemic areas, and 

- global risk for all other individuals.   

Individuals with multiple sexual partners – global risk  

-- Since the start of the global mpox outbreak in 2022, sexual activity in linked sexual networks has been the primary driver of sustained transmission and geographic spread, particularly in newly affected areas. 

-- In Europe and the Americas, up to 96% of cases were among men who have sex with men driven by spread among individuals with multiple sexual partners in a short space of time and frequent partner change. 

-- While sexual behavior data for cases in newly affected African countries remain limited, the contribution of sexual transmission to the introduction, spread and establishment of mpox in communities has been recognized across all affected settings, as in the most recent outbreak in Madagascar. 

-- In several countries, transmission has involved sex workers and their clients, and sexual networks with frequent and multiple partner change.  

-- Sexual contact infection likely occurs during pre-symptomatic or less apparent stages of infection, the duration of which can vary between individuals. 

-- People with few or mild genital lesions might not even recognise the infection. 

-- Although the secondary attack rate for sexual contact is high (estimated at 16-73%), for the epidemic to spread it requires networks characterised by frequent partner change and high rates of partner turnover over short timeframe (days to few weeks). 

-- This pattern was observed during the initial spread of clade IIb among communities of men who have sex with men, as well as in more recent MPXV clade Ib oubtreaks driven – in part – by key populations such as female sex workers and their clients. 

-- We therefore consider within this group of multiple sexual partners, individuals with frequent partner change, and those who may engage in at-risk sexual behaviour, such as people who buy sex.  

(...)

Source: 

Link: https://www.who.int/publications/m/item/who-rapid-risk-assessment---mpox--global-v.6

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