#Sweden - High pathogenicity avian #influenza #H5N1 viruses (Inf. with) (#poultry) - Immediate notification

 

This is a farm with broiler parents, housed in 3 barns. Clinical signs of increased mortality and severely depressed general condition were observed. Euthanization is in progress. A protection zone (3 km) and a surveillance zone (10 km) have been put in place around the infected farm and all other restrictions and necessary measures according to Regulation (EU) 2016/429 and EU DR 2020/687 are applied.

Source: WOAH.

Link: https://wahis.woah.org/#/in-review/7313

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Evolutionary #lineage and #host origin influence #virulence and #mammalian adaptation of #H7N9 avian #influenza viruses

 

Abstract

The H7N9 avian influenza virus (AIV) has posed a major global public health concern since its first detection in China in 2013. Transmitted among wild birds and poultry, this virus has crossed the species barrier to infect humans, causing severe respiratory disease and high mortality. Although the widespread use of H7 vaccines has markedly reduced human infections, the ongoing circulation and adaptive evolution of the virus in poultry remain a serious threat. In this study, we analyzed three highly pathogenic H7N9 isolates collected in China in 2022, representing two hemagglutinin (HA) gene evolutionary lineages: Group.y.2.3 (isolate 229-4, chicken origin; isolate 782-2, quail origin) and Group.y.2.4 (isolate 621, quail origin). Pathogenicity was compared through phylogenetic analysis, molecular characterization, and infection experiments in both avian and mammalian models. Group.y.2.3 isolates displayed stronger replication and pathogenicity in chickens and mice, with isolate 782-2 being the most virulent. The chicken-origin isolate 229-4 caused more severe weight loss and higher viral loads in the lungs of mice, indicating that host origin influences cross-species transmission potential. Molecular analyses revealed that all isolates possessed multiple basic cleavage sites and mutations linked to mammalian adaptation, including HA 186 V. Some isolates also harbored newly acquired glycosylation sites associated with immune evasion. Overall, our findings demonstrate that both genetic lineage and host origin shape the biological characteristics of H7N9 isolates. Group.y.2.3 isolates warrant priority in surveillance, providing critical insights for vaccine updates and risk assessment.

Source: 

Link: https://www.sciencedirect.com/science/article/pii/S0032579126002555?via%3Dihub

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#Zanamivir - #Amantadine Conjugate: A Dual-Action Agent with Broad-Spectrum Synergistic #Antiviral Efficacy

 

Abstract

Influenza A virus is a highly contagious respiratory pathogen, and its rapid and continuous adaptive mutations for immune escape have limited the efficacy of existing vaccines and antiviral drugs. Here, we report a multimechanism anti-influenza platform based on the conjugation of zanamivir (ZMV) with amantadine (Aman). Aman acts as a hydrophobic tag that promotes the degradation of neuraminidase and concurrently enhances the physicochemical properties of ZMV, leading to improved membrane permeability and a significantly prolonged half-life. Meanwhile, the ZMV moiety counteracts Aman-induced cytotoxic autophagy. The resulting conjugate, compound 7j, exhibits potent activity against a wide range of neuraminidase and M2 ion channel mutations. Notably, a single intravenous dose of 7j fully protected mice from a lethal H1N1 challenge. Our work demonstrates that the rational fusion of ZMV and Aman achieves synergistic multimechanistic antiviral activity with enhanced efficacy and safety, offering a new strategy for the development of next-generation anti-influenza drugs.

Source: 

Link: https://pubs.acs.org/doi/10.1021/acs.jmedchem.5c03547

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#Synergy between HA #cleavage site #sequence and NA-mediated #plasminogen recruitment as a virulence mechanism for low-pathogenic avian #influenza

 

ABSTRACT

An outbreak of H3N1 low-pathogenic avian influenza virus (LPAIV) in Belgium in 2019 caused unexpected levels of mortality and morbidity in poultry. These viruses possess an NA polymorphism associated with plasminogen (PLG) binding, as well as an atypical sequence around the HA cleavage site; accordingly, HA cleavage mediated by NA-driven PLG recruitment has been proposed to underlie their systemic spread and pathogenicity. To test this, we established a reverse genetics system for A/chicken/Belgium/460/2019 and created single mutations in HA (K345R) and NA (S122N) that restored the viruses to normal consensus, as well as an HA/NA double mutant. Confirming previous work, trypsin-independent spread and HA cleavage of wild-type Ck/Belgium were observed in the presence of fetal bovine serum containing PLG in vitro. Dose-dependent HA cleavage and trypsin-independent spread were also observed in the presence of purified chicken PLG. Compared to the wild-type virus, both HA cleavage and virus spread in vitro were reduced by the HA K345R mutation and further blocked by the NA mutation S122N. PLG-mediated HA cleavage was seen in a variety of avian cell lines and chicken organoids, excluding cell type-dependent effects. Furthermore, in ovo tests showed that mutant viruses unable to recruit PLG were less able to replicate systemically in chicken embryos. Bioinformatics analyses revealed other viruses that could potentially recruit PLG, including two independent outbreaks of H6N1 viruses, one of which we confirmed PLG-driven spread in vitro. We conclude that PLG recruitment by NA is a general virulence mechanism of N1 LPAIVs.

Source: 

Link: https://journals.asm.org/doi/full/10.1128/mbio.02466-25?af=R

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#Tecovirimat for the Treatment of #Mpox

 

Abstract

Background

Tecovirimat is approved for smallpox treatment under the Food and Drug Administration Animal Rule on the basis of efficacy in nonhuman primate models of mpox (previously known as monkeypox). However, the clinical efficacy of tecovirimat against human clade II mpox is unclear.

Methods

In a phase 3, international, double-blind, randomized, placebo-controlled trial, we evaluated the efficacy of oral tecovirimat in adults with laboratory-confirmed clade II mpox. Participants were randomly assigned in a 2:1 ratio to receive tecovirimat or placebo for 14 days. The primary outcome was clinical resolution, assessed in a time-to-event analysis in participants with active skin or mucosal lesions. Secondary outcomes included reduction in pain, assessed in all participants with laboratory-confirmed mpox and in those with severe pain at baseline (pain score, 7 to 10; scale, 0 [no pain] to 10 [worst pain imaginable]); complete lesion healing (assessed in a time-to-event analysis); viral DNA clearance; and safety.

Results

Of 412 participants who underwent randomization (275 to tecovirimat and 137 to placebo), 344 had laboratory-confirmed mpox, and 336 had active skin or mucosal lesions and were included in the primary analysis. By day 29, the estimated cumulative incidence of clinical resolution was 83% with tecovirimat and 84% with placebo; the competing-risks hazard ratio for clinical resolution was 0.98 (95% confidence interval [CI], 0.74 to 1.31; P=0.89). No substantial between-group differences were seen in pain reduction among participants with severe pain (difference, 0.1 point; 95% CI, −0.8 to 1.0), in complete lesion healing (competing-risks hazard ratio, 0.97; 95% CI, 0.75 to 1.26), or in viral DNA clearance. The incidence of adverse events of grade 3 or higher was similar in the two groups (4% with tecovirimat and 3% with placebo).

Conclusions

This trial showed no evidence that tecovirimat therapy shortened the time to clinical resolution, reduced pain, or increased viral clearance among adults with clade II mpox. (Funded by the National Institute of Allergy and Infectious Diseases of the National Institutes of Health; STOMP/A5418 ClinicalTrials.gov number, NCT05534984.)

Source: 

Link: https://www.nejm.org/doi/full/10.1056/NEJMoa2506495?af=R&rss=currentIssue

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#Wastewater #Surveillance for #SARS-CoV-2 in Rural #Kentucky, 2021–2023

 

Abstract

Wastewater testing for SARS-CoV-2 provided useful public health information during the COVID-19 pandemic yet was underutilized in rural communities. We addressed this gap by implementing wastewater surveillance and assessing its performance in 10 communities in Eastern Kentucky. We collected wastewater samples 1–2 times weekly at 10 wastewater treatment plants (WWTPs) from May 2021 until April 2023 and measured SARS-CoV-2 RNA concentrations using polymerase chain reaction testing. We calculated time-lagged correlations between wastewater concentrations and county-level reported COVID-19 cases by site. We developed a generalized linear model to estimate COVID-19 incidence from wastewater SARS-CoV-2 concentrations. The 10 participating WWTPs served 2430 to 35,575 customers, and 90% were in rural counties. We cumulatively analyzed 818 wastewater samples. Correlations between wastewater SARS-CoV-2 concentrations and COVID-19 cases were significant at seven of the WWTPs and were strongest during the Delta variant period. The incidence density model predicted more COVID-19 cases during the latter study period (May 2022–April 2023) than were officially reported. Wastewater surveillance data in these rural communities corroborated clinical case data and may have more accurately described community disease levels later in the pandemic.

Source: 

Link: https://www.mdpi.com/1999-4915/18/3/282

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Re-infection with #SARS-CoV-2 is associated with increased #antibody breadth and potency against diverse #sarbecovirus strains

 

ABSTRACT

The ease with which emerging SARS-CoV-2 variants escape neutralizing antibodies limits the protection afforded by a prior exposure, be it infection or vaccination. While rare, broadly neutralizing antibodies with activity toward diverse sarbecoviruses have been detected in convalescent serum. Motivated by findings that plasma responses show increased neutralization breadth and potency with continued antigen exposure, we isolated monoclonal antibodies (mAbs) after a SARS-CoV-2 re-infection and compared them to those isolated 1 year prior, after the first breakthrough infection. Among clonal lineage members identified at both time points, mAbs from the later time point showed improved neutralization potency and breadth. One mAb isolated after re-infection, C68.490, targets a conserved region in the receptor binding domain and shows remarkable activity not only against SARS-CoV-2 variants, but also diverse sarbecoviruses from more distant clades present in animal reservoirs. These findings suggest that a focus on individuals with diverse and repeated antigen exposure could lead to the identification of antibodies with therapeutic utility not just toward current and future SARS-CoV-2 variants, but also distant sarbecoviruses in the event of a future spillover.

Source: 

Link: https://journals.asm.org/doi/full/10.1128/mbio.03612-25?af=R

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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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#Argentina - #Influenza A #H5 viruses of high pathogenicity (Inf. with) (non-poultry including wild birds) (2017-) - Immediate notification

 

{A Coscoroba Swan. By Charles J. Sharp - Own work, from Sharp Photography, sharpphotography.co.uk, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=179069673}

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{A Black-Necked Swan. By Charles J. Sharp - Own work, from Sharp Photography, sharpphotography.co.uk, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=178158764}

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{A Fulvous Whistling Duck. By JeffreyGammon - Own work, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=158156460}

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{A Brown-Hooded Gull. By Charles J. Sharp - Own work, from Sharp Photography, sharpphotography.co.uk, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=179073441}

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Contact with wild migratory birds present in the area is presumed to be the likely source of infection. Virological analysis has identified the presence of the H5 subtype of high pathogenicity avian influenza (HPAI). The determination of the neuraminidase subtype is pending in order to complete the characterisation of the pathogenic agent. Further information is provided in the epidemiological comments of the outbreak.

Source: 

Link: https://wahis.woah.org/#/in-review/7291

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#Argentina - High pathogenicity avian #influenza #H5 viruses (Inf. with) (#poultry) - Immediate notification

 

At a heavy breeding poultry farm located in the province of Buenos Aires, an increase in mortality and the presence of clinical signs consistent with high pathogenicity avian influenza (HPAI) were observed. Given the clinical suspicion, official intervention was carried out, including a health inspection and the collection of diagnostic samples for processing. Laboratory analyses confirmed a positive result for high pathogenicity avian influenza subtype H5 (HPAI H5).

The event occured on a farm raising heavy breeding stock. On 21/02/2026, the National Service of Agri-Food Health and Quality (SENASA) received a notification concerning mortality and clinical signs consistent with high pathogenicity avian influenza (HPAI) which began on 19/02/2026, as reported by the reporting person. On 22/02/2026, the suspicion was officially addressed with the restriction of the establishment and taking of samples for official diagnosis. On 23/02/2026, the samples tested positive for HPAI H5. All the birds on the establishment will be culled. We will update the population data in subsequent follow-up reports.

Source: 

Link: https://wahis.woah.org/#/in-review/7290

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#Report on #influenza viruses received and tested by the #Melbourne #WHO CC for #Reference and Research on #Influenza during 2024

 

Abstract

As part of its role in the World Health Organization (WHO) Global Influenza Surveillance and Response System (GISRS), the WHO Collaborating Centre for Reference and Research on Influenza in Melbourne received 12,180 human influenza-positive samples during 2024. Viruses were analysed for their antigenic, genetic, and antiviral susceptibility properties. Selected viruses were propagated in qualified cells or embryonated hens’ eggs for potential use in seasonal influenza virus vaccines. During 2024, influenza A(H1N1)pdm09 and A(H3N2) viruses predominated, accounting for 33% and 42%, respectively, of all viruses received, compared to 5% for influenza B/Victoria. Of note, one influenza A(H5N1) virus was also received in 2024. The majority of A(H1N1)pdm09 (98%), A(H3N2) (88%) and influenza B (100%) viruses analysed at the Centre were found to be antigenically and genetically similar to the respective WHO recommended vaccine strains for the Southern Hemisphere in 2024. Of 4,007 samples tested for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir, twelve A(H1N1)pdm09 viruses and one B/Victoria virus showed highly reduced inhibition against oseltamivir or zanamivir. Of 3,294 total samples sequenced for baloxavir susceptibility, 18 of the 1,825 A(H3N2) samples were identified with genetic evidence of reduced susceptibility to baloxavir marboxil in the PA gene.

Source: 

Link: https://ojs.cdi.cdc.gov.au/index.php/cdi/article/view/3449

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Longitudinal #assessment of functional #antibodies to a novel #influenza virus strain across age groups

 

Abstract

Newly emerging influenza virus strains pose a constant threat as they encounter a population lacking neutralizing antibodies against the new strain. However, cross-reactive non-neutralizing antibodies (nnABs) may be present and assist in mitigating disease symptoms via various effector mechanisms, including antibody-dependent cellular cytotoxicity (ADCC). Although nnABs to influenza virus have received more attention lately, little information is available on their age-related prevalence, steady-state levels, functional properties, and changes in these parameters over time. Using longitudinal samples from adolescents, adults, and older adults, collected before and after the 2009 swine flu pandemic, we comprehensively characterized the specificity and functionality of nnAB responses against H1N1 pandemic 2009 (H1N1pdm09) virus. Remarkably, all participants exhibited cross-reactive antibodies to this virus before having encountered it through infection or vaccination, with the highest baseline levels observed in older adults. The levels of these IgG antibodies showed a strong correlation with engagement of fragment crystallizable γ receptor IIIa (FcγRIIIa) and ADCC activity, both of which were notably lower in adolescents compared to adults and older adults. Without infection or vaccination, average amounts of H1N1pdm09-reactive antibodies remained relatively stable on population level over the 5-year study period. However, on an individual level, substantial increases and decreases occurred. H1N1pdm09 infection or vaccination significantly enhanced specific antibody levels and the FcγRIIIa-engaging capacity of these antibodies in all age groups. ADCC-mediating antibodies increased however only in adolescents, reaching the same level as observed in the adult groups. Taken together, our results demonstrate the presence of cross-reactive, non-neutralizing, functional, and boostable antibodies against a never-encountered influenza virus strain across all age groups. These antibodies can potentially contribute to protection from severe disease. Accordingly, in case of a newly emerging virus, their further enhancement by vaccination could be beneficial as an immediate protective measure before a strain-specific vaccine becomes available.

Competing Interest Statement

The authors have declared no competing interest.

Funding Statement

This study did not receive any funding

Source: 

Link: https://www.medrxiv.org/content/10.64898/2026.02.21.26346781v1

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Evaluating #primer and #probe #mismatch tolerance in an #Influenza A #matrix gene RT #qPCR using contemporary human and zoonotic strains

 

Abstract

Background: 

Genetic drift and host-associated adaptation in influenza A viruses threaten the long-term reliability of RT-qPCR-based diagnostics, particularly when nucleotide mismatches arise within primer and probe binding regions. Conventional assay evaluations often emphasize sequence conservation but rarely assess functional mismatch tolerance across divergent subtypes and hosts. 

Methods: 

We performed an in silico evaluation of a matrix (M) gene–targeted RT-qPCR assay by aligning primer and probe binding regions against 22 H1N1 isolates and representative H3N2 and H5N1 reference strains, including recent zoonotic isolates from avian and bovine hosts. Nucleotide mismatches were identified, quantified, and mapped relative to assay components and oligonucleotide termini. Mismatch burden was summarized by subtype and assay region. 

Results: 

H1N1 isolates exhibited complete conservation across primer and probe regions. In contrast, H3N2 and H5N1 strains demonstrated subtype-specific sequence variability, with a total of eleven mismatches identified across seven non-H1N1 isolates (mean mismatch per isolate = 2.43). Probe mismatches predominated (63.6%), occurring primarily at internal positions, while primer mismatches were infrequent and largely avoided 3′ terminal nucleotides. Recent H5N1 isolates (2023–2024) shared conserved internal mismatches in the probe and forward primer, whereas a historical H5N1 isolate (2016) exhibited a distinct profile including a terminal probe mismatch. Despite this variability, mismatch patterns were consistent with preserved amplification potential. 

Conclusion: 

This study demonstrates that the evaluated influenza A M gene RT-qPCR assay exhibits inherent mismatch tolerance across human and zoonotic subtypes. By shifting diagnostic evaluation from strict sequence identity to functional resilience, our findings provide a framework for designing and maintaining robust molecular assays suitable for surveillance and pandemic preparedness amid ongoing viral evolution.

Source: 

Link: https://www.biorxiv.org/content/10.64898/2026.02.23.707407v1

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Primary bovine embryonic #fibroblasts demonstrate variable #fitness following #infection with avian influenza #H5N1 strains and are susceptible to a recently circulating human #H1N1pdm09 strain

 

ABSTRACT

The recent emergence of highly pathogenic avian influenza (HPAI) H5N1 (clade 2.3.4.4b, genotype B3.13) in dairy cattle presents substantial challenges to the agricultural sector and public health. Mechanistic studies of infection and transmission in cattle have proven difficult due to animal handling restrictions and the limited availability of established cell culture models. Primary bovine embryonic fibroblasts (BeEFs) were isolated and investigated here as a model to study influenza A virus (IAV) infection dynamics. We compared sialylation profiles, infectious virus production, viral replication, and plaque morphology in BeEFs following infection with the bovine HPAI H5N1 and an earlier 2.3.4.4b genotype (B1.1) isolated in 2022. The data presented here demonstrate increased expression of α-2,3 sialic acids compared to α-2,6 sialic acids in BeEFs, similar to sialylation profiles previously reported in bovine mammary tissue. These data also display increased viral fitness of the bovine origin HPAI H5N1 strains across bovine and avian cell lines, consistent with previous characterization in bovine mammary tissue. Furthermore, BeEFs were fully susceptible to a 2022 H1N1pdm09-like IAV strain while maintaining resistance to the 2009 H1N1pdm09 IAV as previously characterized in mammary cells. This study highlights the ongoing zoonotic adaptation of HPAI H5N1 in mammals and the potential for coinfection with select human H1N1 2009 pandemic lineage strains, enabling the potential development of reassortant strains. These data support the ability of BeEFs to serve as a complementary in vitro system for studying IAV infections in bovine hosts.

Source: 

Link: https://journals.asm.org/doi/10.1128/spectrum.03285-25

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#SARS-CoV-2 Error Catastrophe Under #Molnupiravir: #Mutagenic Enhancement Enables Viral #Persistence with Impaired Fitness

 

Abstract

Molnupiravir induces mutations that render severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) replication-competent through error catastrophe mechanisms. Previous studies showed no resistant virus emergence during prolonged molnupiravir treatment, with no resistant variants reported. However, these approaches were limited by genetic uniformity at passage initiation. To investigate viral population dynamics under enhanced genetic diversity, we employed mutagenic pre-treatment using 5-fluorouracil (5-FU) and favipiravir to generate diverse quasi-species populations before molnupiravir selection pressure. Viral populations were treated with stepwise increasing molnupiravir concentrations (10 μM ⟶ 25 μM ⟶ 40 μM) over ten serial passages. Viral detectability, plaque morphology, and mutation accumulation were analyzed using molecular and sequencing approaches. Only high-concentration favipiravir (1000 μM) pre-treatment maintained detectable viral RNA through ten passages under 40 μM molnupiravir, while favipiravir (500 μM) and 5-FU groups became undetectable after passage 6. Surviving populations formed extremely small plaques with markedly reduced replication capacity. Next-generation sequencing revealed extensive mutation accumulation across viral proteins, including polymerase proteins. Individual viable virus isolation was unsuccessful, and large-scale propagation could not be achieved. These findings demonstrate apparent survival rather than true resistance to molnupiravir, characterized by severely compromised viral fitness.

Source: 

Link: https://www.mdpi.com/1999-4915/18/2/273

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#Uruguay - #Influenza A #HxNx viruses of high pathogenicity (Inf. with) (non-poultry including wild birds) (2017-) - Immediate notification

{Coscoroba Swan. By Charles J. Sharp - Own work, from Sharp Photography, sharpphotography.co.uk, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=179069673}

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On February 19, 2026, park rangers from the National System of Protected Areas (SNAP) reported observing two birds of the same species displaying neurological signs. They were able to access one of the animals, which subsequently died. The carcass was properly preserved and sent to the official laboratory for analysis. The emergency protocol was immediately activated. An area of 5 kilometres around the point of detection was defined. There are no commercial poultry farms within the area under analysis. The Official Veterinary Services of the departments of Maldonado and Rocha are visiting establishments in the area. The survey consists of identifying the establishment and owner; georeferencing; confirming the presence of birds (chickens/multiple species); evaluating management conditions and the existence of bird or other species mortality in the previous week. To date, 40 establishments have been visited and no clinical signs compatible with avian influenza have been observed on any of the inspected properties. Actions continue at the site.

Source: 

Link: https://wahis.woah.org/#/in-review/7281

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The #bovine mammary #gland as a crucible for zoonotic #influenza virus emergence: Receptor-mediated #adaptation of HPAI #H5N1 clade 2.3.4.4b

 

Abstract

The recent emergence of highly pathogenic avian influenza (HPAI) H5N1 clade 2.3.4.4b in U.S. dairy cattle marks a pivotal shift in the ecology of influenza A viruses (IAVs), signaling an unexpected expansion into a major livestock species. This review explores the molecular mechanisms underpinning this cross-species transmission, focusing on the unique sialic acid receptor landscape of the bovine mammary gland as a critical determinant. We synthesize emerging evidence that this tissue, which co-expresses both avian-type (α2,3-linked) and human-type (α2,6-linked) sialic acid receptors, functions as a novel biological crucible for viral adaptation. Within this environment, H5N1 virus faces selective pressure for hemagglutinin (HA) mutations—such as Q226L and N193D—that can alter receptor binding specificity toward human-like glycans, potentially bridging the species barrier. Recent studies confirm that bovine H5N1 virus isolates exhibit dual receptor-binding avidity and that single HA mutations are sufficient to shift binding preference to human receptors. The unprecedented mammalian spread of clade 2.3.4.4b, coupled with its capacity for reassortment and the recent case of a dairy farm worker infection, underscores an urgent zoonotic and pandemic threat. This review contextualizes the outbreak within the fundamental principles of influenza virus receptor biology and viral evolution, highlighting critical knowledge gaps that must be addressed through integrated surveillance and multidisciplinary research. Understanding the interplay between host receptor distribution and viral plasticity in this new niche is paramount for mitigating the risk of a future influenza virus pandemic emerging from the bovine reservoir.

Source: 

Link: https://link.springer.com/article/10.1007/s00705-026-06529-0

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Hematogenous #neuroinvasion and genotype-dependent #transmission of #influenza A #H5N1 viruses in the #cat host

 

Abstract

The spillover of highly pathogenic avian influenza (HPAI) A H5N1 virus to mammalian hosts raises major concerns due to its pandemic potential. Cats are frequently affected mammals, often succumbing to systemic and neurological disease. Here, we characterized the pathogenesis and transmissibility of two H5N1 genotypes, B3.13 and D1.1, in cats. Infected cats exhibited high-level viremia and virus shedding in nasal, oral, and fecal secretions were consistently detected. The virus replicated initially in the upper respiratory tract and lungs, followed by systemic dissemination and neuroinvasion. Notably, the virus crossed the blood-brain-barrier by infecting endothelial cells, spreading to astrocytes and neurons, causing multifocal encephalitis. D1.1-virus infection caused protracted disease with lower shedding and no transmissibility, whereas B3.13 virus caused rapid onset with efficient shedding and transmission. These findings reveal critical H5N1 neuropathogenesis mechanisms and highlight mammalian transmission potential in a species with close human contact.

Competing Interest Statement

The authors have declared no competing interest.

Source: 

Link: https://www.biorxiv.org/content/10.64898/2026.02.21.707182v1

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History of Mass Transportation: The C&O class M-1 #500 Baldwin Steam Turbine Locomotive

 

By The only mark on the card is EKE. - eBay itemcard frontcard back, Public Domain, https://commons.wikimedia.org/w/index.php?curid=17618573

Source: 

Link: https://en.wikipedia.org/wiki/Baldwin_Locomotive_Works

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The Fight between Carnival and Lent, Pieter Bruegel the Elder (1559)

 

Public Domain.

Source: 

Link: https://www.wikiart.org/en/pieter-bruegel-the-elder/the-fight-between-carnival-and-lent-1559-1

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