ETIDIOH - NEW

  {Summary} Time Period: August 03, 2025 - August 09, 2025 -- H5 Detection :  2 sites ( 0.5% ) -- No Detection :  425 sites ( 99.5% ) -- No samples in last week :  33 sites (...) Source: US Centers for Disease Control and Prevention,  https://www.cdc.gov/nwss/rv/wwd-h5.html ____

Abstract The continuous evolution and widespread dissemination of highly pathogenic avian influenza (HPAI) H5N1 viruses , particularly clade 2.3.4.4b, pose critical challenges to global pandemic preparedness . In this study, we assessed a low-dose inactivated split virus vaccine derived from clade 2.3.4.4b H5N1, formulated with an Alum/CpG adjuvant , using a preclinical mouse model . This vaccine induced potent humoral and cellular immune responses , generating high titers of cross-reactive antibodies targeting both hemagglutinin (HA) and neuraminidase (NA) glycoproteins across homologous and heterologous H5 clades. The Alum/CpG adjuvant enabled significant antigen dose-sparing while promoting a balanced Th1/Th2 immune profile . Functional analyses demonstrated strong virus neutralization , neuraminidase inhibition, and potent antibody-dependent cellular cytotoxicity activity . Additionally, the vaccine elicited robust antigen-specific CD4+ and CD8+ T cell responses and effectively con...

  Abstract A 2023 outbreak of highly pathogenic avian influenza in seabirds in Norway caused substantial environmental contamination of grazing areas frequented by local sheep . Eleven months later, 220 sheep were tested for antibodies to type A influenza and H5 subtype using ELISA, haemagglutination inhibition, and microneutralisation assays. One ewe (0.5%) tested positive by all methods, consistent with prior spillover infection . This underscores the importance of restricting livestock access to outbreak areas to mitigate cross-species transmission and zoonotic risk. Source: BioRxIV,  https://www.biorxiv.org/content/10.1101/2025.08.14.670265v1 ____

Abstract Avian influenza A viruses (AIVs) pose a significant pandemic threat due to their cross-species transmission potential . However, AIV surveillance at the critical “ migratory birds–poultry-exposed population ” interface remains limited. Between 2021 and 2024, we implemented a prospective One Health surveillance program around Nansi Lake , monitoring AIVs in migratory birds, poultry, and environmental samples, as well as serological investigations against representative AIVs among migratory birds or poultry-exposed subjects. AIVs were detected in 2.1% (30/1417) of migratory bird samples and 10.2% (100/978) of poultry samples . Among these, we identified ten highly pathogenic avian influenza (HPAI) H5 subtype viruses, one HPAI H7N9 virus, and five low pathogenic avian influenza (LPAI) H9N2 viruses. Phylogenetic analysis revealed evidence of frequent genomic reassortment events involving H5 subtype viruses among migratory birds, poultry, and humans . Serological investigation also...

Abstract In early 2024, an unprecedented outbreak of H5N1 high pathogenicity avian influenza was detected in dairy cattle in the USA . As of mid-2025 the epidemic is ongoing, resulting in spillbacks into poultry, wild birds and other mammals including humans . Here, we present molecular and virological evidence that the cattle B3.13 genotype H5N1 viruses rapidly accumulated adaptations in polymerase genes that enabled better replication in bovine cells and tissues, as well as cells of other mammalian species including humans and pigs . We find evidence of several mammalian adaptations gained early in the evolution of these viruses in cattle including PB2 M631L , which is found in all cattle sequences, and PA K497R , which is found in the majority. Structurally, PB2 M631L maps to the polymerase-ANP32 interface, an essential host factor for viral genome replication . We show that this mutation adapts the polymerase to better interact with bovine ANP32 proteins , particularly ANP32A, and ...

  Abstract The ongoing panzootic of H5N1 high pathogenicity avian influenza virus (HPAIV) has caused the deaths of over half a billion wild birds and poultry, and has led to spillover events in both wild and domestic mammals , alongside sporadic human infections . A key driver of this panzootic is the apparent high viral fitness across diverse avian species , which facilitates an increased interface between wild and domestic species. Columbiformes (pigeons and doves) are commonly found on poultry premises , yet little is known about their potential role in contemporary HPAIV disease ecology. Here we investigated the epidemiological role of pigeons (Columba livia) by determining their susceptibility using decreasing doses of clade 2.3.4.4b H5N1 HPAIV (genotype AB). We investigated infection outcomes and transmission potential between pigeons and to chickens. Following direct inoculation , pigeons did not develop clinical signs, and only those inoculated with the highest dose shed vi...

Abstract An extensive survey for the detection of Highly Pathogenic Avian Influenza virus (HPAIV) H5 in seabird species is reported here . It was conducted between December 2023 and January 2024 , in thirteen breeding sites spanning from the northeastern sector of the Antarctic Peninsula to the Ross Sea , including the coasts of the Bellingshausen Sea and the Amundsen Sea . Nine individuals from Pygoscelis adeliae and Leucocarbo bransfieldensis tested positive for RT-PCR amplification of a H5 segment of HPAIV in two different locations on the Antarctic Peninsula . This study suggests the possibility of the first cases of HPAIV H5 in the Antarctic continent, potentially adding two new species to the list of infected species. It also highlights the southernmost suspected cases identified to date of surveillance, and notably, no cases were detected between the Antarctic Peninsula and the Ross Sea. Source: Scientific Reports,  https://www.nature.com/articles/s41598-025-14651-3 ____

  ABSTRACT Influenza A virus (IAV) infection of the respiratory tract can cause both respiratory and non-respiratory symptoms . Gastrointestinal (GI) symptoms such as diarrhea, vomiting, and abdominal pain can occur in persons with seasonal influenza A or novel IAV infections , but the extent to which IAVs can infect and replicate in GI tissues is understudied. The ongoing outbreak of A( H5N1 ) IAV in US dairy cattle associated with sporadic human infections has highlighted the potential public health threat posed by the introduction of infectious virus into materials that may be consumed by humans , such as milk. Here, we review epidemiologic reports documenting the frequency of GI complications in humans infected with seasonal and novel IAVs and present laboratory studies supporting the capacity of IAV to replicate in mammalian GI tissues , with an emphasis on A(H5N1) viruses. Studies assessing the ability of IAV to cause mammalian infection following consumption of virus-contain...

  ABSTRACT The mammary gland is an essential organ for milk production, providing essential immune and nutritional support to offspring and supplying dairy products for human consumption. In both humans and animals , the lactating mammary gland is susceptible to bacterial and viral infections , which can lead to mastitis and, in some cases, vertical transmission to offspring , with potential adverse effects on infant health. However, until recently, the role of respiratory viruses in mammary gland infection has been relatively understudied, particularly their ability to infect mammary epithelial cells and transmit through lactation. The recent emergence of highly pathogenic avian influenza H5N1 clade 2.3.4.4b in dairy cattle has demonstrated the virus’s capacity to replicate in the mammary gland, cause mastitis, and produce high viral loads in milk . This raises significant concerns about the potential for zoonotic transmission to humans and other animals in contact with infected d...

  {By gary noon - Flickr, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=4077294 } __ {England, Devon} Premises with 5200 pheasants. Increased mortality, reduced water consumption and other clinical signs were reported. Samples were taken and were tested positive for HPAI H5N1. Source: WOAH,  https://wahis.woah.org/#/in-review/6716 ____

ABSTRACT The 2.3.4.4b clade highly pathogenic avian influenza H5N1 infected diverse non-human mammalian species , gained mammal-to-mammal transmission potential , and caused sporadic human infections . However, whether non-human mammals enable the human adaptation of 2.3.4.4b H5N1 to establish human infections is unclear. Gain-of-function research restrictions may hinder the assessment of 2.3.4.4b H5N1 human adaptations. Here, we tracked the evolution of 2.3.4.4b H5N1 that infected non-human mammals and evaluated their ability to gain human adaptations. The non-human mammal 2.3.4.4b H5N1 partly acquired classical human-adapting mutations , which are identical to the residues of H1N1pdm09 and seasonal human H3N2 viruses, while showing a few species-specific adaptations that might be potential barriers for successful human infections. The polymerase complex proteins , PA and PB2, acquired human adaptations in non-human mammals, with fox-infected viruses showing more positive selection in...

Abstract The first known human infection with a highly pathogenic H5N1 influenza A virus appeared in China in 1997 . Between 2003 and 2017, the WHO documented an additional 862 human cases, mainly from southeast Asia and Egypt , with a mean annual case fatality rate of 56%. By 2006, the susceptibility of cats to severe respiratory and neurologic disease became apparent. Scientists raised concerns regarding the potential for domestic cats to transmit novel pathogenic strains to humans. But after 2006, reports of new H5N1 infections in companion animals dwindled, and human cases fell after 2016. In 2021, H5N1 clade 2.3.4.4b viruses suddenly appeared in Europe and spread rapidly to the Americas , wreaking havoc on wildlife and crippling the poultry and dairy industries . Between 2022 and 2025, dozens of domestic cats died , most often following raw food consumption . Unease regarding the transmission potential of pets resurfaced. Although most human infections in the Americas were mild an...

  Abstract Importance :  Highly pathogenic avian influenza (HPAI) A H5N1 has been recognized for nearly three decades as a threat to avian species and as a virus with pandemic potential if spillover into human populations occurs. Recently the virus has evolved capacity to infect many mammalian species , including dairy cattle , increasing the risk for human exposure and the pandemic threat. Sialic acids (SA) serve as binding sites for influenza viruses. The distribution of SA determines infectivity of specific influenza viruses across species and tissue tropism . Hemagglutinin (HA) of human and swine adapted influenza viruses bind primarily to SA with α2,6-galactose linkages and avian influenza viruses preferentially bind to SA with α2,3-galactose linkages . Recently, the bovine udder was found to contain SA with α2,3 linkages which allow the H5N1 virus to bind to bovine udder epithelium and to infect milk. The distribution of SA receptors in the human mammary gland is unknown...

  ABSTRACT The H5N1 strain of influenza A virus (IAV) continues to cause severe infections in a range of avian and mammalian species , including sporadic but concerning cases in humans. There is growing concern that circulating H5N1 strains could lead to widespread human outbreaks . Research with highly pathogenic H5N1 viruses is restricted to Biosafety Level 3 (BSL-3) laboratories. Vesicular stomatitis virus (VSV)-based vaccine vectors expressing heterologous viral proteins from Ebola, SARS-CoV-2, Lassa virus, etc., have previously been shown to be safe and effective in animal models and human clinical trials . Here, we report the development of a recombinant VSV expressing the hemagglutinin (HA) and neuraminidase (NA) genes of H5N1 IAV (H5N1-VSV), which serves as a versatile platform to study various aspects of H5N1 IAV biology. H5N1-VSV replicated robustly to titers comparable to those of the full H5N1 virus in multiple cell lines. In mice , H5N1-VSV vaccination was safe, elicit...

  {Summary} Time Period: July 27, 2025 - August 02, 2025 -- H5 Detection :  4 sites ( 0.9% ) -- No Detection :  430 sites (99.1%) -- No samples in last week :  24 sites (...) Source: US Centers for Disease Control and Prevention,  https://www.cdc.gov/nwss/rv/wwd-h5.html ____

  Two Poultry Farms in the Odisha State. Source: WOAH,  https://wahis.woah.org/#/in-review/6694 ____

Abstract Highly pathogenic avian influenza A(H5N1) clade 2.3.4.4b virus infections have caused substantial mortality events in marine mammals in recent years. We hypothesized that the high number of infections and disease severity could be related to cell tropism in respiratory tracts . Therefore, we examined the attachment pattern of an H5N1 clade 2.3.4.4b virus (H52022) as a measure for cell tropism in the respiratory tracts of harbor seals, gray seals, harbor porpoises, and bottlenose dolphins and compared it with an H5N1 clade 2.1.3.2 virus (H52005) and a human seasonal H3N2 virus using virus histochemistry. Both H5 viruses attached abundantly to olfactory and respiratory mucosa in the upper respiratory tract of both seal species. H52022 attached more abundantly than H52005 to epithelial cells in the lower respiratory tract of all species. The observed attachment possibly explains the susceptibility of marine mammal species for recent H5N1 viruses and the observed development of se...

  On 30th July 2025 HPAI H5N1 was confirmed in a young chicken in a backyard flock in Co Donegal . The bird was submitted to the Regional Veterinary Laboratory and virological testing confirmed HPAI at the CVRL. Control measures were put in place following detection on 30th July 2025. The 7 remaining birds of the backyard flock were euthanised and have tested negative for AI PCR. Further results to follow. Update: report updated to reflect the control measures applied (stamping out applied) as per the above report. Source: WOAH,  https://wahis.woah.org/#/in-review/6691 ____

{Scotland, Aberdeenshire} Commercial layer flock with approx. 88,000 laying hens. Increased mortality and other clinical signs reported. Samples taken were found positive for HPAI H5N1. Source: WOAH,  https://wahis.woah.org/#/in-review/6695 ____

{England, Norfolk} Commercial indoor unit with 59562 turkeys. 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/6693 ____