ETIDIOH - NEW

  Abstract Background :  The COVID-19 pandemic , driven by the SARS-CoV-2 virus, has become an unprecedented global public health challenge . Comprehensive investigation of the virus transmission dynamics requires exploration of all potential routes , including the role of animal reservoirs . This study aimed to assess the presence of SARS-CoV-2 RNA and antibodies in urban rodents captured within two landscape units (low-income neighborhoods and green spaces) in the metropolitan area of Buenos Aires (MABA), Argentina. Methods :  Between July 2020 and September 2022, 125 synanthropic rodents (68 Rattus norvegicus, 22 R. rattus, and 35 Mus musculus) from seven low-income neighborhoods and seven green spaces in the MABA were captured and examined for SARS-CoV-2 exposure and infection by indirect immunofluorescence serology and RT-qPCR, targeting the N, E, and ORF1ab genes. Results :  Two M. musculus and six R. norvegicus from five different low-income neighborhoods test...

  Abstract The Goose/Guandong lineage of highly pathogenic avian influenza virus [A/Goose/Guangdong/1/1996(H5N1)] is the progenitor of the currently circulating Eurasian-lineage highly pathogenic avian influenza H5N1 clade 2.3.4.4b and has been the most consequential highly pathogenic avian influenza lineage globally. Despite increased reports of infections, the extent of exposure and role of wild mammals in the ecology and transmission dynamics of the virus remains poorly understood. We surveyed wild mammals in Ohio, United States to investigate the potential spillover of highly pathogenic H5N1 avian influenza clade 2.3.4.4b. While no active infections —defined as positive results indicative of viral replication and potential propagation—were detected by swab-based molecular tests, serological assays revealed antibodies against multiple avian influenza virus antigens in raccoons and opossums . Specifically, antibodies to avian influenza virus nucleoprotein were detected in 54.9% (...

  Abstract The H5N1 highly pathogenic avian influenza (HPAI) virus has caused severe global losses, reaching South America in 2022 and Antarctica in 2024 . Here we synthesize outbreak reports submitted to the World Organization for Animal Health (WOAH) by South American countries and document the virus's unprecedented expansion into Antarctica , affecting wild birds, wild mammals , and domestic poultry . More than 6 million domestic birds died or were culled, mostly from commercial operations . Of the 11 South American countries that reported H5N1 to WOAH, 10 reported infections in wild birds , spanning 104 species , 59.62% of which are migratory and predominantly non-trans-equatorial . Marine mammal cases occurred after wild bird detections, with the South American sea lion (Otaria flavescens) most affected, and several Antarctic bird species with migratory behavior were also reported in South America. To complement outbreak data, we examined available genomic sequences through ph...

  Abstract In North-East Germany's offshore islands and mainland coast, wild ruminants, boar, and carnivores were tested for H5-HPAI antibodies . Wild ruminants were seronegative ; 3.5% of boar and 12.5-21.9% of carnivores were seropositive , evidencing frequent spillover . Because such events may accelerate mammalian - and ultimately human - adaptation , sustained One-Health monitoring is essential. Competing Interest Statement The authors have declared no competing interest. Funder Information Declared European Union, 101084171 "KAPPA-FLU" Helmholtz Institute for One Health, WiMoPOH Source: BioRxIV,  https://www.biorxiv.org/content/10.1101/2025.09.30.678011v1 ____

  Abstract Since 2020, the outbreak of high pathogenicity avian influenza (HPAI) H5N1 virus clade 2.3.4.4b has turned into the largest documented panzootic 1,3. Here, we describe its arrival into the Indian Ocean sub-Antarctic archipelagos of Crozet and Kerguelen , where we first detected the virus in October 2024 in dead southern elephant seals . While the panzootic is ongoing, it has already caused unprecedented mortalities of marine mammals and seabirds . We collected brain swabs from seal and seabird carcasses and obtained 25 novel HPAI H5N1 2.3.4.4b sequences . Using phylogeographic analyses, we show that there have been independent introductions of the virus to Crozet and Kerguelen islands , most likely from the distant South Georgia islands in the Southern Atlantic , and not from the more nearby coasts of South Africa . Our results point to a year-long gap in genomic surveillance in the sub-Antarctic region. Locally, our analyses show that the virus is transmitted between di...

  {Excerpt} Highly pathogenic avian influenza caused by H5N1 viruses emerged in East Asia in the late 1990s and spread to Europe, Africa, and the Middle East , circulating in wild and domestic birds and occasionally spilling over into mammals and humans . These viruses are classified into genetic lineages called clades based on differences in the gene encoding hemagglutinin , a key surface protein involved in cell entry. In 2021, one such lineage, clade 2.3.4.4b , crossed from Europe to Canada . It spread rapidly, reaching the southern tip of South America in less than 2 years and causing massive mortality in seabirds and marine mammals , including South American sea lions (Otaria flavescens) and southern elephant seals (Mirounga leonina) (1). However, human mortality has been markedly lower in the present H5N1 outbreak than in past ones. If the virus evolves the capacity to transmit from human to human, understanding this reduction will be essential for mounting an effective respo...

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...

ABSTRACT The high-altitude ecosystems of Qinghai Province, China, harbor unique viral communities shaped by extreme environmental conditions and host adaptations. This study presents a comprehensive genetic characterization of the marmot gut virome , revealing novel viral strains with zoonotic potential . Using viral metagenomics, we analyzed intestinal contents from 70 marmots collected from Chengduo and Maqin counties. Sequencing on the Illumina NovaSeq 6000 platform identified 19 viral genomes belonging to four major families : Adenoviridae, Astroviridae, Parvoviridae, and Picornaviridae , along with four novel circular Rep-encoding single-stranded DNA (CRESS DNA) viruses. Phylogenetic analyses demonstrated close relationships between marmot-derived strains and viruses from humans, bats, and other mammals , highlighting potential cross-species transmission risks . Notably, bat-associated adenoviruses showed closer phylogenetic proximity to human strains, while novel parvoviruses for...

Abstract Avian influenza viruses undergo frequent genetic reassortment, which can coincide with phenotypic changes in transmission, pathogenicity, and host species niche . Since 2020, clade 2.3.4.4b H5 high pathogenicity avian influenza viruses (HPAIVs) have driven a global panzootic , causing mass mortality in wild birds, poultry , and, for the first time, repeated spillover infections in a variety of mammalian species . This resurgence of H5 HPAIV has coincided with a dramatic increase in the number of circulating reassortant strains ; however, the scale, impact and drivers of these reassortants remain unknown. Here, we combined statistical and phylodynamic modelling to reconstruct the global evolutionary dynamics of H5Nx viruses across four epizootic seasons (2020-2024). We identified 209 genetically distinct reassortants , stratified into three transmission categories based on their phylogenetic and epidemiological profiles. Accounting for sampling depth and HPAIV incidence, we est...

Abstract Introduction :  In 2023 and 2024, mass mortalities of swans occurred on the Caspian coast of Kazakhstan , which affected more than seven hundred birds of a local population of 10–15 thousand. It is widely known that viral infections significantly affect the microbiome content of various organisms , but the influence of H5N1 infection in the gut microbiota of wild birds remains little studied. Almost no information is available on postmortem microbial changes after the devastating impact of H5N1 influenza. Methods :  In addition to standard routine virological studies , we were interested in investigating the microbiological changes resulting from infection with the highly pathogenic H5N1 using 16S rRNA gene sequencing. Results :  Virological studies of samples taken from the dead swans identified the highly pathogenic influenza virus H5N1 subtype as the primary cause of mortality. 16S analysis of samples from freshly dead swans revealed patterns of microbial dysb...

{Excerpt} To the Editor : The article “Henipavirus in northern short-tailed shrew, Alabama, USA,” (1), describing the discovery of Camp Hill virus (family Paramyxoviridae ) in the northern short-tailed shrew (Blarina brevicauda), sparked major media attention and raised concerns about zoonotic transmission and potential pandemic risk. However, it would be advisable to reevaluate this virus discovery within the broader context of related viruses. The increase in identified henipa-like viruses in various shrew species (2–4) led the International Committee on Taxonomy of Viruses to classify these henipa-like viruses into a distinct genus, Parahenipavirus (5), acknowledging their genetic difference from the highly pathogenic Hendra and Nipah virus. (...) Source: US Centers for Disease Control and Prevention,  https://wwwnc.cdc.gov/eid/article/31/8/25-0401_article ____

Abstract Sampling of mammal communities across the United States during 2022–2023 detected evidence of SARS-CoV-2 antibodies in 3 new species and 2 previously described species and evidence of influenza A antibodies in 2 previously described species . Our analysis provides surveillance and sampling guidance for detection of rare exposure events. Source: US Centers for Disease Control and Prevention,  https://wwwnc.cdc.gov/eid/article/31/8/24-1671_article ____

ABSTRACT In recent years, high pathogenicity avian influenza viruses (HPAIVs) have spread among wild, captive, and domestic birds, as well as mammals . Beyond the resulting economic and ecological losses , spillover into mammals has raised concerns about a potential pandemic . Viral tropism refers to the spectrum of host species, organs, and cells susceptible and permissive to viral infection . It is a potent driver of infection dynamics and shedding patterns, which presents important variations both between and within hosts: in poultry, HPAIV leads to systemic endothelial infection in domestic chickens , whereas neurological and selective epithelial infections are observed in domestic ducks . In mammals , infection can result in respiratory and neurological disease , but the recent outbreaks in domestic dairy cows highlighted a unique and remarkable adaptation to the mammary gland prone to viral shedding in milk. The present review explores viral tropism of HPAIV across recent spillov...

Abstract The November 2021 introduction of highly pathogenic avian influenza A(H5N1) clade 2.3.4.4b into North America triggered a devastating outbreak , affecting more than 180 million domestic birds and spreading to more than 80 wildlife species across Canada and the US . From this outbreak, we have sequenced 2955 complete A( H5N1 ) viral genomes from samples collected in Canada and, in conjunction with previously published data, performed multifaceted phylodynamic analyses. These analyses reveal extensive diversification of A(H5N1) viruses via reassortment with low-pathogenic avian influenza viruses. We find evidence of repeated ancestral strain replacement by direct descendants, indicative of compounding viral fitness increases . Spatiotemporal modeling identified critical geographic areas facilitating transcontinental spread and demonstrated genotype-specific host dynamics, offering essential data for ongoing control and prevention strategies. Source: Science Advances,  https:...

Summary The recent emergence of highly pathogenic H5N1 avian influenza virus infections in dairy cows and humans in the U.S. has raised alarms regarding the potential for a pandemic . Over 995 dairy cow herds and at least 70 humans have been affected, including cases of severe disease and the first reported H5N1-related death in the U.S . Sporadic human infections with no known contact with infected animals highlight the possibility of viral adaptation for efficient human-to-human transmission. Concurrently, the virus continues to circulate in wild birds, backyard flocks, and hunted migratory species , further amplifying the risk to humans and domestic animals. This article provides an overview of the current outbreak status , emphasizes the importance of robust surveillance systems to detect emerging strains with pandemic potential, and highlights risks to the U.S. dairy and poultry industries. Recommendations for risk mitigation include enhanced biosecurity measures, improved surveil...

Abstract Despite identification of Highly Pathogenic Avian Influenza viruses nearly 75 years ago, the transmission pathways among wild animals remain incompletely described. We propose the use of social networks , to complement phylodynamic modeling , for better surveillance, prediction, and prioritization of HPAI. Source: PLoS Pathogens,  https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1013233 ____

Abstract Zoonotic diseases pose global public health threats, prompting various interventions to limit their emergence and spread . One increasingly common response by governments has been to ban wildlife hunting , trade and consumption. However, there is limited evidence of the effectiveness of wildlife trade bans . Here we assess compliance with Nigeria’s wildlife trade ban—enacted to curb the spread of mpox (formerly monkeypox)—by analysing approximately 4.5 years of wild meat sales data from 19 vendors in southeast Nigeria (988 vendor-months) alongside interviews with vendors and law enforcement officials. After matching the sales data by time of year, we found no significant differences before and after the ban in the number of vendors selling wild meat per week, the weekly mass of wild meat sold, or the weekly price per kilogram of wild meat; however, the total weekly sales price was higher post-ban. These findings, supported by interview insights, indicate widespread non-complia...

Abstract The Highly Pathogenic Avian Influenza Virus (HPAIV) H5 clade 2.3.4.4b has caused severe outbreaks in domestic and wild birds worldwide since its emergence in 2014, and especially since 2020, with outbreaks in Europe and North America . The introduction of the virus into South America was reported for the first time in Colombia in October 2022, followed by outbreaks in other South American countries affecting poultry, wild birds, mammals , and humans . In this study, a phylogenetic and mutation analysis of the hemagglutinin (HA) gene of HPAIV H5N1 2.3.4.4b viruses isolated in South America was performed to analyze its evolution and its transmission and zoonotic potential . The analysis shows an increase in the viral effective population size between April and June 2022, which was followed by multiple outbreaks of HPAIV H5N1 clade 2.3.4.4b in South America . Moreover, the virus variants evolved from a recent common ancestor estimated to have existed in June 2017. The mean rate o...

Simple Summary The present commentary deals with the pandemic risk brought about by the highly pathogenic avian influenza (HPAI) A(H5N1) virus . Such a pandemic alarm is justified, among others, by the progressively and rapidly expanding range of virus-susceptible hosts , including humans alongside a significant number of domestic and wild avian and mammalian species , several of which appear to be geographically and phylogenetically distant from each other. Despite its well-established zoonotic potential , no clear-cut evidence of a sustained and efficient HPAI A(H5N1) virus interhuman transmission has thus far been reported. Should this happen in a more or less near future, it could pave the way for a new pandemic. Based upon the above, a “ One Health, One Earth, One Ocean ”-focused, holistic approach would be the necessary prerequisite to deal in an appropriate way with the HPAI A(H5N1) virus-associated zoonotic and pandemic risk. Abstract The focus of this commentary is represented...

Abstract Highly pathogenic avian influenza (HPAI) has become a critical threat to wildlife, shifting from a seasonal epizootic to a persistent, year-round panzootic with global consequences . Here, we summarize the origin, evolutionary mechanisms, and expanding host range of the current H5N1 virus (clade 2.3.4.4b) and assess its impact on wildlife . Over the past five years, HPAI has caused the deaths of millions of wild birds , causing dramatic population declines in several seabird species . However, comprehensive quantitative mortality data remain scarce, as existing records are often anecdotal, focus on localized mass die-offs, and thus represent only a fraction of the true magnitude of mortality. This gap in data limits the ability to predict outbreak dynamics and mitigate long-term consequences. Using the Northwestern European Sandwich Tern (Thalasseus sandvicensis) population as a case study, we demonstrate the value of integrating mortality data with ecological, serological and...