#Update: First locally acquired #human case of #H7N7 #influenza A was detected in #Taiwan (CDC, May 5 '26)

 

-- The Taiwan Centers for Disease Control (CDC) announced today (April 5) that regarding the first locally transmitted case of H7N7 novel influenza A reported on April 2 involving a poultry farmer, the CDC has completed gene sequence comparison and analysis. 

-- Furthermore, after joint assessment of the overall impact by agricultural and health authorities, the public health risk rating for Taiwan is "low risk."

-- The CDC pointed out that the patient was discharged from isolation on April 3, and the 33 identified contacts completed health monitoring on April 6, with no confirmed cases of novel influenza A. 

-- There is no risk of the outbreak expanding. 

-- This case was discovered due to the high level of vigilance of the hospital physician, who reported the case based on clinical symptoms, contact history, and preliminary test results, leading to confirmation of novel influenza A. 

-- Therefore, the CDC will award the reporting physician a NT$10,000 reporting bonus in accordance with Article 5, Paragraph 1, Item 1 of the Infectious Disease Prevention and Control Reward Regulations.

-- The CDC explained that this case was investigated and controlled through cooperation between health and agricultural authorities, based on the national integrated epidemic prevention action. 

-- Gene sequence comparison of the virus showed that it was most similar to the virus strain isolated from wild birds in Japan and South Korea in 2024, and all gene fragments originated from the Eurasian low pathogenic avian influenza virus gene pool, indicating that the virus is highly related to the virus circulating in wild bird populations. 

-- Further analysis showed that the virus's PB2 gene carries the E627K mutation (PB2 E627K). 

-- According to existing research, this mutation may enhance the virus's replication ability in mammalian cells. 

-- However, since it cannot be ruled out that this site is a mutation produced in humans after infection, and no virus with the same characteristics has been found in Taiwan recently, nor have any drug resistance-related mutations been detected, the current assessment is that the risk to the public is low. 

-- In addition, agricultural authorities actively completed sampling at other poultry farms of the case before the Qingming Festival holiday, expanded sampling at five poultry farms near the case, and cooperated with the Wild Bird Association to collect 92 wild bird specimens from the surrounding area, all of which did not detect avian influenza-related viruses.

-- The Taiwan Centers for Disease Control (CDC) stated that, based on the spirit of national epidemic prevention unity, the CDC also launched a joint risk assessment team with agricultural and health authorities on April 1st to conduct a domestic risk assessment of the H7 subtype viruses (including H7N7, H7N2, H7N3, and H7N4). 

-- This risk assessment primarily referenced the framework of the US CDC's Influenza Risk Assessment Tool (IRAT). 

-- Team members collected supporting data and scores for ten risk factors and corresponding assessment questions, followed by a comprehensive evaluation. 

-- The results showed that the overall risk of the four H7 subtype viruses was low. 

-- While the possibility of sporadic local cases in the future cannot be ruled out, direct and indirect contact with animals remains the main transmission route. 

-- No evidence of sustained human-to-human transmission has been found, and the possibility of further community spread is extremely low.

-- In response to the detection of the key PB2 E627K variant in the first domestic H7N7 human infection case and concerns about the lack of herd immunity among the Taiwanese public to the H7 subtype of avian influenza, the Taiwan Centers for Disease Control (CDC) is not only closely monitoring genomic evolution but also convening expert meetings to focus on assessing the risk of cross-species transmission to ensure the disease prevention system can effectively address potential public health threats. 

-- Furthermore, the CDC is continuously strengthening the One Health inter-ministerial surveillance mechanism, maintaining surveillance in poultry farms and wild animals, closely monitoring genomic evolution, raising clinicians' awareness of the need for testing cases of pneumonia of unknown cause with a history of contact with poultry or livestock, and enhancing related prevention and control measures such as antiviral drugs.

-- In its global risk assessment of the H7 subtype of avian influenza, the World Health Organization (WHO) stated that the global H7 subtype of avian influenza is mainly prevalent in wild and domestic poultry populations. 

-- Although there have been occasional cases of human infection through contact with infected animals in the past, these cases have mostly presented with mild symptoms such as conjunctivitis or influenza-like illness. 

-- The Netherlands reported one death case in 2003. 

-- Given the potential impact on public health, close monitoring of human infections of this virus is crucial. 

-- Based on the current lack of evidence of sustained human-to-human transmission or community spread, the WHO assesses the threat to public health as remaining low. 

-- While sporadic human cases cannot be ruled out, the probability of human-to-human transmission is extremely low.

Source: 

Link: https://www.cdc.gov.tw/Bulletin/Detail/N1P8C-k3KudXQW2VAkp9UQ?typeid=9

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Avian #Influenza #Report - From March 29 to April 4, 2026 (Wk 14) (#HK PRC SAR CHP, April 8 '26): 1 #H5N1 case in #Cambodia, 1 #H7H7 case in #Taiwan

{Excerpts}

(...)

1) H5N1

-- Date of report: 31/03/2026 

-- Country: Cambodia 

-- Province / Region: Oddar Meanchey province

-- District / City: Banteay Ampil district 

-- Sex: Male

-- Age: 3 

-- Condition at time of reporting: Hospitalised 

-- Subtype of virus  H5N1 

(...)

2) H7N7

-- Place of occurrence: Taiwan, China

-- No. of cases  (No. of deaths): 1(0)

-- Details:   

- Avian influenza A(H7N7): 

* Central Taiwan: A man in his 70s who works in a poultry farm with onset on March 20, 2026. 

* This is the first locally-acquired human case of avian influenza A(H7N7) reported in Taiwan, China. 

(...)

Source: 

Link: https://www.chp.gov.hk/files/pdf/2026_avian_influenza_report_vol22_wk14.pdf

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#Taiwan, First locally acquired case of #H7N7 avian #influenza A virus has been released from isolation today (MoH, April 3 '26)

 

The Taiwan Centers for Disease Control (CDC) announced today (April 3) that the first case of local human infection with the H7 subtype of novel influenza A, which was detected recently, has been cured and discharged from isolation today after clinical treatment. 

The patient's condition has continued to improve and all tests have been negative. The patient will continue to be monitored until April 6.

The Taiwan Centers for Disease Control (CDC) stated that the sputum sample collected from the case on March 27th was genetically sequenced to identify the virus as H7N7, a low-pathogenic avian influenza virus (LPAI). 

No drug-resistant mutations were found, and the virus remains sensitive to antiviral drugs; the public need not panic. 

The CDC also today, in accordance with the International Health Regulations (IHR), notified the World Health Organization of this first locally acquired H7N7 influenza case through the IHR contact window.

The Taiwan Centers for Disease Control (CDC) explained that since 1959, more than 90 human cases of H7N7 have been reported globally, concentrated before 2003, mainly in Europe. 

Of these, only one case resulted in death, and the vast majority were mild cases of conjunctivitis. 

Subsequently, Italy reported three cases in 2013, also mild cases of conjunctivitis. 

No new human cases have been reported since 2013, but the virus continues to spread and evolve in birds. 

The genetic analysis of the first H7 case in Taiwan showed that it was significantly different from the H7 cases in European human cases 10-20 years ago, and most similar to the H7 cases detected in wild birds in Taiwan over the years. 

No mutations related to enhanced bird-to-human transmission were found, and it is judged to be an isolated event with manageable risks.

The Centers for Disease Control (CDC) reiterates its reminder that workers in the poultry and livestock industries should adhere to disease prevention guidelines, including wearing protective equipment and proper disinfection after handling. 

If respiratory or eye symptoms develop, seek medical attention immediately and inform the animal contact history. 

The public should also follow the "5 Dos and 6 Don'ts" principle to avoid contact with or purchase poultry and livestock products from unknown sources, jointly safeguarding public health and safety. 

More information can be found on the CDC website (https://www.cdc.gov.tw/) or by calling the disease prevention hotline 1922.

Source: 

Link: https://www.cdc.gov.tw/Bulletin/Detail/oWFPJ8DnGZKl-Ygm43iPQQ?typeid=9

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14th Meeting of #WHO #Expert Working Group of the Global #Influenza #Surveillance and Response System (GISRS) for Surveillance of #Antiviral Susceptibility (March 20 '26)

Weekly epidemiological record 

20 MARCH 2026, 101th YEAR, No 12, 2026, 101, 53–56

http://www.who.int/wer 

Executive Summary 

The WHO Expert Working Group on Surveillance of Influenza Antiviral Susceptibility (AVWG) supports the WHO GISRS by providing practical guidance for monitoring antiviral susceptibility of seasonal and emerging influenza viruses through global surveillance efforts. 

The 14th WHO-AVWG meeting was held in virtual format on 10-12 June 2025. 

Update on susceptibility of seasonal influenza viruses to approved antiviral agents 

From approximately May 2024 to May 2025, five WHO Collaborating Centres (CCs) and two National Influenza Centres (NICs) reported co-circulation of influenza A(H1N1) pdm09, A(H3N2), and B/Victoria viruses. 

A(H1N1)pdm09 dominated in Eastern Asia{1}. Elevated frequency of influenza neuraminidase (NA) inhibitor (NAI) reduced inhibition/ highly reduced inhibition (RI/HRI) was identified among A(H1N1)pdm09 viruses, largely conferred by the NA-H275Y substitution. 

Reporting frequency was 3.8% in China, lower (≤1%) in other reporting regions, but still measurable and were in some cases a result of prior antiviral use or specific local outbreaks (e.g., a hospital in Iceland with a NA-H275Y+S247N cluster, a primary school classroom outbreak in Japan{2}. The NA-S247N substitution (≤3.3%) was also noted by three centres, but these viruses exhibited normal inhibition (NI) by NAIs when available isolates were tested. 

Incidence of RI/HRI or NA-associated markers were less frequently reported for A(H3N2) and B/Victoria viruses than A(H1N1)pdm09 viruses. 

Markers and incidence of reduced susceptibility to baloxavir was detected at low frequencies of 0.07 to 2.2%, where the latter value represented a small sample set of only 2 of 89 viruses in Japan. 

Reduced susceptibility or amino acid markers indicative of reduced susceptibility were observed only in influenza A viruses and not influenza B. 

Update on susceptibility of zoonotic and animal influenza viruses  to approved antiviral agents 

From approximately May 2024 to May 2025, global surveillance data from WHO CCs, NICs, and associated partners including WHO Essential Regulatory Laboratories and the OFFLU (WOAH/FAO Network of Expertise on Animal Influenza) network reported that most zoonotic and avian influenza viruses, particularly circulating A(H5N1/x) HA clade 2.3.4.4b and 2.3.2.1a/e viruses, were broadly susceptible to NAIs and baloxavir. 

A(H5N1) 2.3.4.4b virus oseltamivir inhibitory concentrations remain elevated vs. seasonal N1 viruses. 

Small and isolated incidence of NAI associated RI/HRI or markers included: NA-D199G mediated oseltamivir/zanamivir RI detected in A(H5N1) 2.3.4.4b poultry in the Russian Federation (February 2024, reported June 2025), NA-N295S in poultry in India A(H5N1) 2.3.2.1a isolates, and 8 poultry farms in British Columbia, Canada exhibiting A(H5N1) 2.3.4.4b with NA-H275Y. 

Only two viruses with reduced baloxavir susceptibility were identified, 1 human virus with PA-I38M (California, USA) and 1 environmental virus isolate with PA-V100I (China, Hong Kong Special Administrative Region). 

Beyond A(H5N1/x), nearly 30 avian influenza subtypes including A(H9N2), A(H7N2), A(H7N7), and A(H7N9), and A(H10N7) were analysed across surveillance sites in the Bangladesh, Egypt, the Netherlands and the United States of America (USA). 

They generally lacked NA or PA genotypic markers of reduced drug susceptibility and when available for phenotypic testing, were susceptible to both NAIs and baloxavir. 

A(H7N2) and A(H7N7) viruses from the Netherlands displayed oseltamivir RI compared to human seasonal references, but this may be due to foldchange comparison to a mismatched NA subtype. 

Swine-origin variant viruses (A(H1N1)v, A(H1N2)v, A(H3N2)v) tested across the USA and Europe were largely free of genotypic or phenotypic indicators of reduced susceptibility/inhibition to NAIs or baloxavir. 

Some viruses (the  Netherlands) showed slightly higher NAI median inhibitory concentrations to historical or human seasonal baselines, but all remained below NAI RI thresholds. 

Update of protocols and guidance for GISRS laboratories 

Both genotypic and phenotypic assays may be used as tools to monitor susceptibility of influenza viruses to NAIs and baloxavir. 

The WHO-AVWG routinely reviews and updates influenza NA and PA amino acid substitutions associated with reduced susceptibility to NAIs and baloxavir; updated tables for the previous reporting period were included on the WHO website{3–5}. 

The US CDC continues to update and ship reference virus panels that can be used for NAI and baloxavir susceptibility testing, available via the International Reagent Resource{6} 

Further guidance on baloxavir and other PA inhibitor testing included the Influenza Replication Inhibition Neuraminidase-based Assay (IRINA), published by the Centers for Disease Control and Prevention, USA{7} and included on the WHO website{8}. 

The WHO AVWG continues to develop algorithms for NICs to aid in influenza response planning (zoonotic, pandemic, and antiviral resistance-specific events), guidance to aid in decisions making for testing strategies (genotypic vs. phenotypic), and guidance for consideration of baloxavir and PA inhibitor specific amino acid substitutions associated with reduced drug susceptibility{9}. 

Additionally, the WHO-AVWG has worked with GISAID to continue to refine and implement modifications to existing tools to facilitate identification of NA and PA substitutions upon sequence submission. 

Outbreak and pandemic preparedness with clinicians’ perspectives 

Two physicians, Profs. Prof. David Hui and Bin Cao, were invited to present recently updated WHO guidance on clinical practice guidelines for influenza{10}. 

Significant updates and discussion surrounded inclusion of baloxavir, which was conditionally recommended for non-severe disease high-risk patients and post-virus exposure prophylaxis (PEP) including influenza viruses associated with high mortality. 

Conditional recommendation against any NAI or baloxavir intervention remains for non-severe disease low-risk patients or seasonal virus PEP. 

Data was presented on multiple PA inhibitors rapidly moving through late-stage clinical trials in China which may have implications on expanded usage of this newer class of influenza drugs. 

Review of External Quality Assessment Programme (EQAP) panels 

EQAP was initiated in 2007 to monitor the quality of GISRS, NICs, other national influenza reference laboratories’ capacity for influenza diagnosis and detection. 

An optional antiviral phenotypic NAI panel was introduced in 2013, and genotypic baloxavir susceptibility was introduced in 2020. 

Results for the 2024 Global EQAP panel were reported during the 14th WHO-AVWG meeting. 

Of the 194 participating laboratories, 26.3% participated in NAI susceptibility testing. 

Results and subsequent discussion from this year’s panel were used by members of WHO-AVWG to assess the training needs of NICs. 

Way forward 

The 2020–2023 Annual Global Update on the Susceptibility of Influenza Viruses (Global AVS) manuscript was published{11} and drafting of a 2023–2025 publication is underway. The next WHO-AVWG meeting will be held in June 2026.

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{1} World Health Organization. Influenza Transmission Zones. 2026. https://cdn.who.int/media/docs/ default-source/influenza/influenzaupdates/2025_09_24_influenza-transmission-zones. pdf?sfvrsn=22361408_3&download=true. 

{2} Takashita E, Shimizu K, Usuku S, Senda R, Okubo I, Morita H, et al. An outbreak of influenza A(H1N1) pdm09 antigenic variants exhibiting cross-resistance to oseltamivir and peramivir in an elementary school in Japan, September 2024. Euro Surveill. 2024;29(50).

{3} World Health Organization. Summary of neuraminidase (NA) amino acid substitutions assessed for their effects on inhibition by neuraminidase inhibitors (NAIs). 2025. https://cdn.who.int/media/docs/default-source/ influenza/laboratory---network/quality-assurance/human-nai-marker-table_ for-publication_final_20240918.pdf. 

{4} World Health Organization. Summary of neuraminidase (NA) amino acid substitutions assessed for their effects on inhibition by NA inhibitors (NAIs) among avian influenza viruses of Group 1 (N1, N4, N5, N8 subtypes) and Group 2 (N2, N3, N6, N7, N9 subtypes) NAs. 2025. https://cdn.who.int/media/ docs/default-source/influenza/avwg/avian-nai-marker-whotable__10-10-2025.pdf?sfvrsn=bc0d1e9a_10 

{5} World Health Organization. Summary of polymerase acidic protein (PA) amino acid substitutions assessed for their effects on PA inhibitor (PAI) baloxavir susceptibility. 2025. https://cdn.who.int/media/docs/default-source/influenza/ laboratory---network/quality-assurance/antiviral-susceptibility-influenza/ pa-marker-who-table_28-11-2025_updated.pdf?sfvrsn=5307d6fe_4. 

{6} International Reagent Resource. 2026. https://www. internationalreagentresource.org/. 

{7} Patel MC, Flanigan D, Feng C, Chesnokov A, Nguyen HT, Elal AA, et al. An optimized cell-based assay to assess influenza virus replication by measuring neuraminidase activity and its applications for virological surveillance. Antiviral Res. 2022;208:105457. 

{8} World Health Organization. Baloxavir Susceptibility Assessment using Influenza Replication Inhibition Neuraminidase-based Assay (IRINA). https:// cdn.who.int/media/docs/default-source/influenza/avwg/cdc-phenotypic-lp492rev01d---baloxavir-susceptibility-assessment-using-irina.pdf? 

{9} Patel MC, Nguyen HT, Mishin VP, Pascua PNQ, Champion C, Lopez-Esteva M, et al. Antiviral susceptibility monitoring: testing algorithm, methods, and f indings for influenza season, 2023-2024. Antiviral Res. 2025;244:106299. 

{10} World Health Organization. Clinical practice guidelines for influenza 2024. https://www.who.int/publications/i/item/9789240097759.

{11} Hussain S, Meijer A, Govorkova EA, Dapat C, Gubareva LV, Barr I, et al. Global update on the susceptibilities of influenza viruses to neuraminidase inhibitors and the cap-dependent endonuclease inhibitor baloxavir, 2020-2023. Antiviral Res. 2025:106217.

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Source: 

Link: https://iris.who.int/server/api/core/bitstreams/1ea408da-cd90-438b-b80c-b00aaf4e7315/content

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#Glial cells promote #infection by #neurotropic #Influenza A viruses in vitro

Abstract

Although influenza A viruses (IAV) are notorious respiratory pathogens, some IAV strains can reach and replicate in the central nervous system (CNS) in vivo. In particular, highly pathogenic avian influenza viruses (HPAIV) pose a threat for future pandemics and are linked to greater neurotropic potential. Moreover, neurotropic IAV strains have shown a more significant impact on the onset and pathogenesis of neurodegenerative diseases (NDD). However, despite its clinical relevance, the dynamics and cellular tropism of IAV infection in the CNS are not well understood. In this study, we analyzed the replication of HPAIV H7N7 in vitro using a primary murine triple co-culture system comprising neurons, astrocytes, and microglia. We found that microglia become highly infected early on and induce a strong pro-inflammatory response before undergoing apoptosis. Using fluorescence microscopy with automated single-cell profiling, we found that, in contrast to non-neurotropic H3N2, the H7N7 nucleoprotein accumulated in neuronal somata throughout the infection without being transported into dendrites or axons. A combination of single-cell and co-culture replication assays led us to conclude that astrocytes are the primary virus producers of HPAIV H7N7 in the CNS. Our results illuminate the acute phase of neurotropic IAV infection, highlighting its implications for the association between IAV and the development of neurodegenerative diseases.

Source: BioRxIV, https://www.biorxiv.org/content/10.1101/2025.06.20.660606v1

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Exploring Avian #Influenza Viruses in #Yakutia—The Largest #Breeding #Habitat of Wild Migratory #Birds in Northeastern #Siberia

Abstract

Yakutia, the largest breeding ground for wild migratory birds in Northeastern Siberia, plays a big role in the global ecology of avian influenza viruses (AIVs). In this study, we present the results of virological surveillance conducted between 2018 and 2023, analyzing 1970 cloacal swab samples collected from 56 bird species. We identified 74 AIVs of H3N6, H3N8, H4N6, H5N3, H7N7, H10N3, and H11N9 subtypes in Anseriformes order. Phylogenetic analysis showed that the isolates belong to the Eurasian lineage and have genetic similarities with strains from East Asia, Europe, and North America. Cluster analysis has demonstrated the circulation of stable AIV genotypes for several years. We assume that Yakutia is an important territory for viral exchange on the migratory routes of migrating birds. In addition, several amino acid substitutions have been found to be associated with increased virulence and adaptation to mammalian hosts, highlighting the potential risk of interspecific transmission. These results provide a critical insight into the ecology of the AIV and highlight the importance of continued monitoring in this geographically significant region.

Source: Viruses, https://www.mdpi.com/1999-4915/17/5/632

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Different #genetic #determinants for high #virulence, #transmission and #replication of high pathogenicity #H7N7 avian #influenza virus in #turkeys and #chickens

Abstract

High pathogenicity (HP) avian influenza viruses (AIV) generally evolve from low pathogenicity (LP) precursors after transmission from wild birds to chickens (Gallus gallus domesticus) and turkeys (Meleagris gallopavo), causing severe economic losses worldwide. Turkeys are more susceptible to AIV infection than chickens and are considered potential bridging hosts that facilitate the emergence of HPAIV. Beyond the polybasic cleavage site (pCS) in hemagglutinin (HA), little is known about other virulence determinants of HPAIV in these species. In 2015, HPAIV H7N7 and its LP ancestor were isolated from the same chicken farm, which differed by 16 nonsynonymous mutations across all eight gene segments, in addition to the pCS. Here we identify the genetic determinants, including the pCS, that contributed to the HPAIV H7N7 virulence, transmission, replication, and tissue distribution in chickens and turkeys. Notably, the non-structural (NS1) or matrix (M) proteins’ encoding segments in turkeys, or NS segment in chickens, rendered viruses as virulent and transmissible as the original HPAIV. Endotheliotropism, observed exclusively in chickens, was driven by the pCS and, to a lesser extent, the neuraminidase (NA). In vitro, the M2-V68L mutation influenced NS1 expression and virus morphology in chicken and turkey cells. Additionally, HPAIV NS1 enhanced polymerase activity and effectively suppressed interferon induction, a process further modulated by M2-V68L. These findings underscore the critical role of turkeys as a “hub” in the evolution of HPAIV from LP precursors, offering crucial insights into the genotypic and phenotypic factors that facilitate viral adaptation in different poultry species.

Source: BioRxIV, https://www.biorxiv.org/content/10.1101/2025.03.18.643940v1?rss=1

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High cumulative #viral titers of #influenza virus in #animals with significant disease #fatality rates indicate a potential trade-off between fatality and transmissibility

Abstract

Evaluating the trade-off hypothesis for the evolution of virulence using empirical data poses significant challenges. The hypothesis suggests that pathogens evolve to maximize transmissibility, but fatality imposes limits as there are diminishing gains in transmissibility. In this study, we analyzed a secondary dataset of influenza virus infections in ferrets (Mustela putorius furo), categorized by Hemagglutinin (HA) and Neuraminidase (NA) subtypes. Subgroups defined by the H7/N9 and H7/N7 combinations exhibited fatality rates of approximately 30% and reached cumulative viral titers close to 7.5 (log10 titer/mL). These levels represent intermediate fatality rates, as the H5/N6 and H5/N1 subgroups had higher fatality rates but reached lower cumulative viral titers. Using cumulative viral titer as a proxy for potential secondary transmissions, the analysis suggests that intermediate fatality rates are associated with higher numbers of secondary transmissions. However, there are significant uncertainties in subgroups with lower or no fatalities. Additionally, subgroups without fatalities showed substantial variability in cumulative viral titers.

Source: BioRxIV, https://www.biorxiv.org/content/10.1101/2024.12.11.627227v1 

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