ETIDIOH - NEW

Abstract Highly pathogenic H5N1 avian influenza viruses (HPAIV) belonging to lineage 2.3.4.4b emerged in Chile in December 2022, leading to mass mortality events in wild birds, poultry, and marine mammals and one human case . We detected HPAIV in 7,33% (714/9745) of cases between December 2022–April 2023 and sequenced 177 H5N1 virus genomes from poultry, marine mammals, a human, and wild birds spanning >3800 km of Chilean coastline . Chilean viruses were closely related to Peru’s H5N1 outbreak, consistent with north-to-south spread down the Pacific coastline . One human virus and nine marine mammal viruses in Chile had the rare PB2 D701N mammalian-adaptation mutation and clustered phylogenetically despite being sampled 5 weeks and hundreds of kilometers apart . These viruses shared additional genetic signatures , including another mammalian PB2 adaptation (Q591K, n = 6), synonymous mutations, and minor variants. Several mutations were detected months later in sealions in the Atlanti...

 A poultry farm in Durrës Region. Source: WOAH,  https://wahis.woah.org/#/in-review/6305 ____

 A poultry farm in Sachsen Region. Source: WOAH,  https://wahis.woah.org/#/in-review/6301 _____

This is a farm with pheasants for game restocking . The birds are being euthanized 27 February  A protection zone (3km) 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) 2020/687. Source: WOAH,  https://wahis.woah.org/#/in-review/6297 ____

Summary -- What is already known about this topic? -  Highly pathogenic avian influenza A(H5N1) outbreaks have emerged in U.S. cattle and poultry . Wastewater surveillance detects influenza A(H5) subtype but does not currently distinguish between human and animal sources. -- What is added by this report? -  During September 15, 2021–July 11, 2024 , retrospective analysis of wastewater surveillance data revealed 21 avian influenza A(H5) subtype detections across 12 Oregon communities . No association was found between detections in a community’s wastewater and history of a poultry outbreak or presence of dairy processing facilities or dairy farms within the sewershed. Avian influenza A(H5) was detected most frequently in two communities with important wild bird habitats . -- What are the implications for public health practice? -  Wastewater surveillance was an early indicator of avian influenza emergence in Oregon. Nonhuman and noncattle animal inputs , including wild bir...

Abstract In late 2021, Eurasian-lineage highly pathogenic avian influenza (HPAI) A(H5N1) viruses from HA clade 2.3.4.4b were first detected in the United States . These viruses have caused severe morbidity and mortality in poultry and have been detected in numerous wild and domestic animals , including cows and humans . Notably, infected cows transmitted the virus to cats , causing extreme pathogenicity and death. While human-to-human spread of the virus has not been recorded, efficient transmission of the bovine-origin virus has also led to extreme pathogenicity and death in ferret models . Recently, markers in PB2 (E627K) and HA (E186D, Q222H), indicating mammalian adaptation mutations , were detected in an H5N1-infected patient manifesting critical illness in Canada . These, combined with instances of interspecies spread of the virus , have raised global public health concerns. This could highlight the potential for the virus to successfully adapt to mammals, posing a serious risk o...

Abstract Highly Pathogenic Avian Influenza H5N1 (HPAI H5N1) was first detected in chickens in Scottland in 1959 and has since circulated globally, causing regular outbreaks among different animal species, as well as incidental infections in humans . In this scoping review, the epidemiology and impact of HPAI H5N1 among migratory birds, poultry, and cattle in the United States were analyzed, with a particular focus on outbreaks since January 2022. Following PRISMA guidelines, a total of 27 articles were identified for this review. Publicly available data and reports from the USDA and CDC were also evaluated and summarized. The identified articles primarily included epidemiological studies of detections in wild birds, mammals, and case reports on H5N1 and transmission dynamics among cattle , with a notable absence of poultry-focused reports . Wild birds, especially migratory species, have played an important role in virus dissemination. Studies among mammals , including seals, bears, and...

Note 20/02/2025 : this immediate notification is linked to the avian influenza cases detected in cats and reported in event 6276. HPAI - H5N1 virus was detected in poultry droppings, poultry waste swab, meat cutting table swab, and knife swab collected from the live bird market {in Madhya Pradesh}. Source: WOAH,  https://wahis.woah.org/#/in-review/6277 ____

{Automatic Translation} Since 2020, the world has seen an increase in the number of outbreaks of avian influenza caused by the highly pathogenic avian influenza A (H5N1) virus and an expansion of the geography of circulation of this virus. In 2024, more than 1.2 thousand outbreaks of influenza A (H5N1) among wild birds and about 2 thousand outbreaks among poultry were registered in the world. The infection affected 68 countries in Asia, Europe, Africa, North and South America, and also reached Antarctica. In addition, in 2024, a large number of cases of detection of the influenza A (H5N1) virus among wild and domestic mammals were recorded, including with subsequent infection of people. These include outbreaks among cattle on US dairy farms, which by the end of the year affected more than 900 dairy farms in 16 states. The avian influenza A (H5N1) virus, isolated from cows, also caused illness in 40 people - farm workers. At the same time, the influenza A(H5N1) viruses detected in cows ...

Abstract Since 2022, three cases of human infections of novel H3N8 avian influenza viruses (AIVs) have been confirmed in China . Given the potential for significant public health implications , the prompt detection and containment of the virus is particularly important. Comprehensive analyses were conducted of the complete viral gene sequences of five H3 subtype AIVs that were isolated from chickens, pigeons, and geese in live poultry markets in China in 2023. Four strains exhibited a high degree of homology with the H3N8 viruses responsible for human infections in 2022 and 2023. A subsequent study was conducted to investigate the pathogenicity differences among multiple subtypes of the H3 AIVs in chickens. The study revealed that all infected chickens exhibited clinical signs and viral shedding. Notably, two H3N8 viruses, which were highly homologous to human strains, demonstrated significant differences in adaptability to chickens. The goose-derived H3N5 strain displayed high adaptab...

 A poultry farm in Vlaanderen Region. Source: WOAH,  https://wahis.woah.org/#/in-review/6280 ____

 Ducks and commerical poultry of various age groups. Source: WOAH,  https://wahis.woah.org/#/in-review/6278?reportId=172354&fromPage=event-dashboard-url ____

Backyard poultry in Niamey Region. Source: WOAH,  https://wahis.woah.org/#/in-review/6259 ____

Abstract We report the detection of a clade 2.3.4.4b A(H5N1) reassortant virus with a neuraminidase surface protein derived from a North American lineage low-pathogenic avian influenza virus. This virus caused a widespread and ongoing outbreak across 45 poultry farms in British Columbia, Canada . Isolates from 8 farms reveal a mutation in the neuraminidase protein (H275Y) that is exceptionally rare among clade 2.3.4.4b viruses (present in 0.045% of publicly available clade 2.3.4.4b isolates). NA-H275Y is a well-known marker of resistance to the neuraminidase inhibitor oseltamivir . We demonstrate that this substitution maintains its resistance phenotype on the genetic background of H5N1 clade 2.3.4.4b viruses. Source: Emerging Microbes and Infections,  https://www.tandfonline.com/doi/full/10.1080/22221751.2025.2469643 ____

National Service of Agri-Food Health and Quality (SENASA) received a notification concerning a high mortality of birds and signs consistent with high pathogenicity avian influenza (HPAI) in a backyard . The suspicion was immediately addressed and samples were taken for analysis. The samples tested positive for HPAI H5. The affected species are chickens, ducks and turkeys . The affected premises are adjacent to a body of water , so contact with wild birds is presumed. Stamping out, sanitary burial, cleaning and disinfection of all the birds in the premises will be carried out. We will update the quantitative data in subsequent follow-up reports. Source: WOAH,  https://wahis.woah.org/#/in-review/6272 _____

On January 24, 2025 , the Canadian Food Inspection Agency (CFIA) was notified of mortality in a non-commercial backyard layer poultry farm in Newfoundland and Labrador. The CFIA National Centre for Foreign Animal Disease has confirmed on February 12, 2025 that the virus was H5N5 . The HA of the H5 virus from the samples belongs to Eurasian Gs/GD lineage HPAI H5N1 (2.3.4.4b) with cleavage site motif of “PLREKRRKR/GLF”, compatible with HPAI viruses. The sample contained AI virus similar to European like - H5N5 (2023) viruses which came to Canada via the Atlantic flyway . The viruses contained wholly Eurasian H5N5 genome segments . The CFIA has immediately quarantined the IP and is implementing strict movement controls and a stamping out policy. Primary control zone (PCZ) has been put in place around the IP. Surveillance is ongoing in the affected areas. WOAH data on poultry and non-poultry can be visualized and extracted on the AI dashboard in domestic birds available at https://cahss.ca...

A total of 390 birds belonging to various individual backyard owners in a village . The birds included various species such as chickens, geese, and ducks . There are no commercial poultry operations within the village or the surrounding 10km surveillance zone. In Hatay Region. Source: WOAH,  https://wahis.woah.org/#/in-review/6270 ____

ABSTRACT Influenza A viruses with fewer amino acids in the neuraminidase (NA) stalk domain are primarily isolated from chickens rather than wild ducks , indicating that a shortened NA stalk is considered an adaptation marker of avian influenza viruses (AIVs) to chickens. Experimental passages of an H7N7 nonpathogenic AIV (rgVac2-P0) in chickens resulted in a highly pathogenic variant (Vac2-P3L4) with a 34-amino-acid deletion in the NA stalk , encompassing five potential N-glycosylation sites. To investigate how amino acid truncation and deglycosylation in the NA stalk contribute to increased pathogenicity, a virus with glycosylation-deficient mutations at these sites (rgVac2-P3L4/P0NAΔGlyco) was constructed. Contrary to expectations, chickens inoculated with rgVac2-P3L4/P0NAΔGlyco exhibited variable clinical outcomes, attributed to the genetic instability of the virus. A single mutation stabilized the virus, and the mutant (rgVac2-P3L4/P0NAΔGlyco-Y65H) resulted in higher pathogenicity ...

A poultry farm in Chhattisgarh State. Source: WOAH,  https://wahis.woah.org/#/in-review/6261 _____

Abstract Understanding the transmission routes of high-pathogenicity avian influenza (HPAI) is crucial for developing effective control measures to prevent its spread. In this context, windborne transmission , the idea that the virus can travel through the air over considerable distances, is a contentious concept and, documented cases are rare. Here, though, we provide genetic evidence supporting the feasibility of windborne transmission . During the 2023-24 HPAI season, molecular surveillance identified identical H5N1 strains among a cluster of unrelated commercial farms about 8 km apart in the Czech Republic . The episode started with the abrupt mortality of fattening ducks on one farm and was followed by disease outbreaks at two nearby high-biosecurity chicken farms. Using genetic, epizootiological, meteorological and geographical data , we reconstructed a mosaic of events strongly suggesting wind was the mechanism of infection transmission between poultry in at least two independen...