ETIDIOH - NEW

  Abstract The highly pathogenic H5N1 avian influenza A virus (IAV) clade 2.3.4.4b has spread globally and spilled over into multiple mammalian species , raising concerns about its pandemic potential . In late 2022, clade 2.3.4.4b viruses devastated seabird and marine mammal populations along the Pacific coast of South America . Here, we report the first evidence of H5 IAV infections in wild bats globally, focusing on common vampire bats (Desmodus rotundus) in coastal areas of Peru . Longitudinal serological screening , stable isotope analysis and metabarcoding revealed repeated exposures to H5 IAVs in vampire bats which feed on coastal wildlife species heavily impacted by the 2.3.4.4b epizootic, but no evidence of infection in populations without access to marine prey. We further report bat gene flow between IAV-exposed and IAV-naive populations , and IAV infections in a vampire bat colony that fed on both marine and terrestrial livestock prey, providing insights into how future I...

  Summary -- What is already known about this topic? - A total of 117 H9N2 cases of human infection of Chinese origin had been reported to the World Health Organization (WHO) by May 9, 2025, with 22 of them originating in Hunan Province. -- What is added by this report? - This article reported on the investigation of three new H9N2 avian influenza virus (AIV) infections detected in Changsha, Hunan Province , in April 2025. No epidemiological link was found among them. Exposure to live poultry was identified as the primary risk factor for infection. Sequence analysis of the three H9N2 AIVs showed a similarity of 99.71%–99.82% between hemagglutinin (HA), and the homology of the neuraminidase (NA) genes was 98.41%–99.83%. Although the tests showed that the HA had enhanced binding ability to upper respiratory tract cells’ receptors , no evidence of sustained human-to-human transmission has been found so far. -- What are the implications for public health practice? - This study indicate...

  Summary -- What is already known about this topic? - The H3N8 avian influenza virus (AIV) demonstrates considerable capacity for interspecies transmission and has been documented in multiple mammalian hosts , including equine and canine species. During 2022–2023, three laboratory-confirmed human infections with H3N8 were reported in China, heightening public health concerns about the zoonotic spillover potential of H3 subtype AIVs. -- What is added by this report? - This study reports the isolation of a genetically reassorted, low-pathogenicity H3N8 avian influenza virus (AIV) from an islet in Niukouyu Wetland Park, Beijing Municipality — the first detection of this viral strain in a wild environment within the city. Throat swabs collected from park staff tested negative for influenza viruses. Phylogenetic analysis demonstrated that the viral hemagglutinin gene originated from the Eurasian lineage, while the neuraminidase gene was derived from the North American lineage . Althoug...

  Abstract Influenza pandemics arise when novel influenza virus subtypes emerge in populations with little or no pre-existing immunity . The recent expansion of H5N1 virus circulation in mammals — including documented spread in cattle and sporadic human infections — coupled with the emergence of mutations associated with enhanced pandemic potential , underscores the persistent threat of novel influenza strains. Pandemic preparedness critically depends on developing effective vaccines capable of providing broad protection across diverse viral strains. While vaccination remains the most effective strategy for preventing influenza and its complications, pandemic vaccine development faces substantial challenges . These include the rapid mutation rates characteristic of influenza viruses, driven by error-prone RNA replication, broad host range, environmental selection pressures, and frequent genetic recombination. Such factors complicate predictions of which strain will trigger the next...

  Authors: Freja CM Kirsebom{1}, Catherine Thompson{2}, Tiina Talts{2}, Beatrix Kele{2}, Heather J Whitaker{3}, Nurin Abdul Aziz{1}, Christopher Rawlinson{1}, Rebecca E Green{1}, Catherine Quinot{1}, Nicholas Gardner{1}, Elizabeth Waller{1}, Alex Allen{1}, Conall H Watson{1,4}, Suzanna LR McDonald{1}, Maria Zambon{2}, Richard Pebody{4,5}, Mary Ramsay{6,7}, Katja Hoschler{2}, Anika Singanayagam{*2,4}, Jamie Lopez Bernal{*1,4}  {*} Joint last authors  {1} Immunisation and Vaccine-preventable Diseases Division, UK Health Security Agency, Colindale, London  {2} Respiratory Virus Unit (RVU), UK Health Security Agency, Colindale, London  {3} Modelling Division, UK Health Security Agency, Colindale, London  {4} NIHR Health Protection Research Unit in Respiratory Infections, Imperial College London, United Kingdom  {5} Epidemic and Emerging Infections Directorate, UK Health Security Agency, Colindale, London  {6} Public Health Programmes Directorate, UK H...

  Abstract Between 2022 and 2025, high pathogenicity avian influenza (HPAI) H5N1 clade 2.3.4.4b was detected in poultry and wildlife across most countries in Central and South America . The epizootic peaked in 2023, subsided in 2024, and resurged in 2025 . In Central America , outbreaks in wildlife were few and small, and mostly affected pelicans . In contrast, South America experienced unprecedented mass mortality in colonial seabirds and pinnipeds , including endangered and endemic species. Notably, viral adaptation enabled mammal-to-mammal transmission in pinnipeds and rapid viral spread across multiple countries along the Pacific and Atlantic coasts . Subsequent introductions to subantarctic islands and Antarctica stemmed from South American viruses. In February 2025, a novel reassortant virus emerged, recombining HPAI H5N1 B3.2 genotype with South American low pathogenicity avian influenza viruses . In May 2025, HPAI H5N1 viruses re-emerged in Brazil , causing a series of outb...