ETIDIOH - NEW

Abstract Transmission of highly pathogenic avian influenza from H5 clade 2.3.4.4b has expanded in recent years to infect large populations of birds and mammals , heightening the risk of a human pandemic . Influenza viruses adapted to transmission in birds and some other animals tend to have a less stable hemagglutinin (HA) than seasonal influenza viruses , enabling membrane fusion at comparatively high pH levels. Here, we combine five mutations within H5 HA that dramatically increase its melting temperature and promote stable closure of the HA trimer . Structural analysis by cryo-electron microscopy revealed that the stabilizing mutations create several new hydrophobic interactions , while maintaining local HA structure. We found that vaccinating mice with stabilized H5 HA immunogens resulted in higher hemagglutination inhibition and neutralization titers than non-stabilized comparators. Epitope mapping of vaccine-elicited polyclonal antibody responses using negative stain electron mic...

  {Excerpt} Time Period: July 20, 2025 - July 26, 2025 -- H5 Detection :  4 sites ( 1.0% ) -- No Detection :  391 sites ( 99.0% ) -- No samples in last week :  38 sites (...) Source: US Centers for Disease Control and Prevention,  https://www.cdc.gov/nwss/rv/wwd-h5.html ____

Abstract Transmission routes of highly pathogenic H5N1 between cows or to humans remain unclear due to limited data from affected dairy farms. We performed extensive air, farm wastewater, and milk sampling on 14 H5N1 positive dairy farms across two different California regions. Virus was detected in the air in milking parlors and from exhaled breath of cows . Infectious H5N1 virus was detected in the air and water streams ; sequence analysis revealed viral variants on a farm in these locations. Longitudinal analysis of milk from the individual quarters of cows revealed a high prevalence of subclinical H5N1 positive cows and a heterogeneous distribution of infected quarters that maintained a consistent pattern over time. Our data highlight potential modes of H5N1 transmission on dairy farms. Competing Interest Statement SSL and LCM receive funds from Flu Lab and NIH. ASL receives funds from Flu Lab, NIH, and CDC. ASL receives consulting fees and research support from Roche, outside of t...

Abstract Background .  Highly pathogenic avian influenza A(H5) viruses pose a pandemic threat , with a history of zoonotic spillovers into humans that are presumed immunologically naive. Whether the general population is currently immunologically naive to circulating A(H5) influenza viruses is unknown.  Methods .  To evaluate the presence of cross-reactive immune responses to emerging A(H5) clade 2.3.4.4b influenza viruses in the general population, we conducted comprehensive immune profiling on cross-sectional samples from healthcare workers (n=107). Samples were collected in August and September 2024 in the scope of an ongoing prospective follow-up study: Surveillance of rEspiratory viruses iN healThcare and anImal workers in the NethErLands (SENTINEL).  Findings .  Low-level antibody responses directed against the A(H5) hemagglutinin (HA) head were detected in a limited number of individuals , but without hemagglutination inhibition activity. Nevertheless, we...

Abstract Influenza A virus (IAV) poses a significant global health risk, with highly pathogenic strains like H5N1 (CFR ~52%) causing severe disease compared to less lethal but more transmissible strains like H1N1 (CFR 0.01-0.03%). Although IAV primarily infects lung epithelial cells , causing cell death and tissue damage , the molecular basis of strain-specific pathogenesis remains poorly understood. Here we show that in cell culture , H5N1 induced more rapid and extensive cell death than H1N1. Since Interferon (IFN) signaling is key to innate immunity, we examined its role in virus-induced cell death using STAT1-knockout A549 cells and JAK/STAT pathway inhibitors like Baricitinib . Both approaches reduced cell death across various IAV strains, including H1N1, H5N1, H7N9 , and H3N2 . However, inhibition increased viral titers , raising concerns about its clinical use in isolation. To overcome this, we tested a combination of Oseltamivir (antiviral) and Baricitinib (anti-inflammatory). ...

Abstract In 2024, highly pathogenic avian influenza A H5N1 caused outbreaks in wild birds, poultry, cows, and other mammals in the United States with 61 human cases also reported by the CDC. Detection of influenza A H5 RNA in wastewater has been previously reported in sewersheds in Texas and North Carolina with nearby impacted dairy herds following the emergence of H5N1 in dairy cows. Here, we conduct retrospective testing of total influenza A and H5 hemagglutinin genes in wastewater as well as present and apply new assays for detection of H1 and H3 genes across a respiratory virus season in an urban California sewershed from September 2023 to May 2024. Total influenza A, H1, and H3 were regularly detected, while H5 was first detected in March . We developed a model that uses Monte Carlo simulations and previously published parameters to estimate the numbers of infected people, poultry, wild birds, or liters of H5-contaminated milk required to result in measured H5 concentrations in wa...

Abstract Highly Pathogenic Avian Influenza (HPAI) viruses, particularly H5N1 and H7N9, have long been considered potential pandemic threats , despite the absence of sustained human-to-human transmission. However, recent outbreaks in previously unaffected regions , such as Antarctica, suggest we may be shifting from theoretical risk to a more imminent threat . These viruses are no longer limited to avian populations. Their increasing appearance in mammals , including dairy cattle and domestic animals , raises the likelihood of viral reassortment and mutations that could trigger a human pandemic. If such a scenario unfolds, the world may face a crisis marked by high transmissibility and lethality, without effective vaccines readily available. Unlike the COVID-19 pandemic, when vaccines were rapidly developed despite inequities in access, the current influenza vaccine production model , largely reliant on slow, egg-based technologies, is insufficient for a fast-moving outbreak. While newe...

Abstract The highly pathogenic avian influenza (HPAI) subtype H5N1 is a severe viral disease which continues to pose a significant threat to public health and a rigorous understanding of its transmission dynamics across its major pathways is essential for developing effective control strategies . Phylogenetic analysis suggests that H5N1 spillover occurs primarily between wild and domestic birds . However, increasing contact between these species and humans increases the risk of zoonotic transmission . In this work, we develop a mathematical model to examine the transmission dynamics of H5N1 and evaluate the effectiveness of proposed control measures. The model employs a compartmental framework that includes human, domestic, and wild bird populations. We then use this model to estimate the basic reproduction number for each population group and perform a sensitivity analysis to assess the contribution of the parameters to the spread of the disease. Numerical simulations are also conduct...

By gary noon - Flickr, CC BY-SA 2.0,  https://commons.wikimedia.org/w/index.php?curid=4077294 {England, Somerset} A game rearing site with approx. 2.500 9-week-old pheasants. Increased mortality and other clinical signs were reported. Samples were taken and were tested positive for HPAI H5N1. Source: WOAH,  https://wahis.woah.org/#/in-review/6679 ____

Abstract Introduction :  Recent intercontinental spread of highly pathogenic avian influenza (HPAI) A( H5N1 ) among kept and wild birds, and transmission to mammalian hosts , including cattle and humans , has heightened the need to review public health risk assessments . Biosecurity is essential for limiting disease spread, but how widely practices are implemented is not fully known.  Methods :  Here, we report on uptake of biosecurity measures and risk perception of avian influenza virus (AIV) in the context of preventing zoonotic transmission to persons potentially at high risk of exposure. Questionnaire data from 225 people in contact with birds in the UK (Avian Contact Study, May to July 2024) was analysed.  Results :  We found hand washing after contact with birds was the most common biosecurity measure implemented (89%, 196/218), followed by using disinfecting footwear dips (78%, 170/218). Individuals in contact with a higher number of birds were more like...

PHNOM PENH, July 29 (Xinhua) -- A 26-year-old man from northwest Cambodia's Siem Reap province has been confirmed for H5N1 human avian influenza, raising the number of the cases to 14 so far this year, the Ministry of Health said in a statement on Tuesday. "A laboratory result from the National Institute of Public Health showed on July 26 that the man was positive for H5N1 virus," the statement said. "The patient has the symptoms of fever, cough, sore throat, stomach ache , and breathing difficulty, and is currently being rescued by a team of doctors," it added. The victim lives in Kravann village of Siem Reap city. "Investigations revealed that there were dead chickens near the patient's house and he also culled and plucked chickens three days before he fell ill," the statement said. Health authorities are looking into the source of the infection and are examining any suspected cases or people who have been in contact with the victim in order to p...

This case indicates the recurrence of the high pathogenicity avian influenza (HPAI) H5N1 subtype (clade 2.3.4.4b) on a poultry farm in Taiwan . The owner of the poultry farm reported the situation to the local veterinary authority in Yunlin County , and samples were collected on July 10. These samples were sent to the National Reference Laboratory for diagnosis on July 11. Clinical signs included increased mortality rates, reduced appetite , and decreased egg production . On July 13, the outbreak was confirmed as HPAI. Subsequently, 2,616 geese were culled, and comprehensive cleaning and disinfection were conducted on July 21. Farms within a 3-kilometer radius of this location will undergo heightened surveillance and visits for the next 28 days. Source: WOAH,  https://wahis.woah.org/#/in-review/6670 ____

Abstract While wild waterfowl are known reservoirs of avian influenza viruses and facilitate the movement of these viruses , there are notable differences in the response to infection across species. This study explored differential responses to infection with highly pathogenic avian influenza in Snow Geese (Anser caerulescens) located in the California Central Valley . Though H5 antibody prevalence was high across years among birds sampled in the winter (75% in both years via hemagglutination inhibition), these values were even higher among birds sampled in summer that failed to migrate (i.e., August 2023 = 100% and August 2024 = 93% via hemagglutination inhibition). Birds that failed to migrate were also generally lighter than birds sampled in the winter and presented notable damage to cerebrum and cerebellum . In December 2022, a single individual positive for infection with H5N1 at the time of sampling indicated reduced movement during the 14 days following sampling but completed s...

  Key points   -- At the present time , based on available information, FAO-WHO-WOAH assess the global public health risk of influenza A(H5) viruses to be low , while the risk of infection for occupationally or frequently exposed (e.g., with backyard poultry) persons is low to moderate depending on the risk mitigation and hygiene measures in place and the local avian influenza epidemiological situation.  -- Transmission between animals continues to occur and, to date, a growing yet still limited number of human infections are being reported. Although additional human infections associated with exposure to infected animals or contaminated environments are expected to occur, the overall public health impact of such infections at a global level , at the present time, is considered minor . The assessment could change if and when additional epidemiological or virological information becomes available.  -- This risk assessment from FAO, WHO and WOAH updates the assessment ...

  Backyard poultry operation in Chobe Region. Source: WOAH,  https://wahis.woah.org/#/in-review/6676 ____

Abstract The 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 as well as limited availability of established cell culture models. Primary Bovine Embryonic Fibroblasts (BeEFs) were collected from a Montana cow and are 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 both BeEFs and chicken DF-1 cells following infection with the bovine HPAI H5N1 and an earlier 2.3.4.4b genotype (B1.1) isolated in 2022. The data presented here show increased viral fitness of the bovine origin HPAI H5N1 strains across multiple species and bovine susceptibility to human seasonal IAV. This study highlights the ability o...

ABSTRACT The ongoing outbreak of highly pathogenic avian influenza (HPAI) H5N1 clade 2.3.4.4b has affected at least 989 dairy herds across 17 states in the United States (U.S.) and resulted in 70 confirmed human infections , underscoring the urgent need to understand the pathogenesis and therapeutic interventions of emerging H5N1 viruses. In this study, we modelled infection with a highly pathogenic recombinant human A/Texas/37/2024 H5N1 (rHPh-TX H5N1) strain using human airway organoids (HAO) to investigate viral replication, innate immune response , infection-induced fibrogenesis, and potential therapeutic interventions . rHPh-TX H5N1 replicated efficiently in HAO, eliciting a robust interferon (IFN) response and pro-inflammatory cytokine production . Prolonged infection led to the accumulation of fibroblast-like cells surrounding infected regions, marked by increased alpha-smooth muscle actin (α-SMA) expression and upregulation of transforming growth factor-beta (TGF-β), indicative ...