ETIDIOH - NEW

Abstract H9N2 avian influenza virus (AIV) is endemic in poultry worldwide and increasingly zoonotic . Despite the long-term widespread use of inactivated vaccines , H9N2 AIVs remain dominant in chicken flocks. We demonstrated that inactivated vaccines did not prevent the replication of H9N2 AIVs in the upper airway of vaccinated chickens. Viral transmission was enhanced during sequential passage in vaccinated chickens, which was attributed to the restricted production of defective interfering particles and the introduction of stable mutations (NP-N417D, M1-V219I, and NS1-R140W) which enhanced viral replication. Notably, the genetic diversity of H9N2 AIVs was greater and included more potential mammal/human-adapted mutations after passage through vaccinated chickens than through naïve chickens, which might facilitate the emergence of mammal-adapted strains. By contrast, vaccines inducing cellular/mucosal immunity in the upper respiratory tract effectively limit H9N2 AIV. These findings ...

{England} Backyard flock of 40 chickens. Increased mortality and other clinical signs were reported. Samples tested positive for HPAI H5N1. Source: WOAH,  https://wahis.woah.org/#/in-review/6401 ____

Abstract The continuous spread of highly pathogenic avian influenza H5 viruses poses significant challenges, particularly in regions with high poultry farm densities where conventional control measures are less effective. Using phylogeographic and phylodynamic tools , we analysed virus spread in Southwestern France in 2020-21, a region with recurrent outbreaks. Following a single introduction, the virus spread regionally, mostly affecting duck farms , peaking in mid-December with a velocity of 27.8 km/week and an effective reproduction number between farms (Re) of 3.8, suggesting the virus can spread beyond current control radii. Transmission declined after late December following preventive culling. Farm infectiousness was estimated around 9 days. Duck farm density was the main driver of virus spread and we identified farm density and proximity thresholds required to maintain effective control (Re < 1). These findings offer actionable guidance to support regional biosecurity and to...

On 31 March 2025 a clinical suspicion was reported to the Danish Veterinary and Food Administration. The affected poultry holding consists of 24 hens. On 1 April 2025 highly pathogenic avian influenza subtype H5N1 was confirmed by the national reference laboratory. A 3 km protection zone and a 10 km surveillance zone has been established. The culling was completed on 1 April 2025. Carcasses will be disposed of by rendering. Source: WOAH,  https://wahis.woah.org/#/in-review/6392 ____

 Death was observed in Guinea Fowl in Jharkhand State. Source: WOAH,  https://wahis.woah.org/#/in-review/6376 ____

 A poultry farm in Sachsen-Anhalt Region. Source: WOAH,  https://wahis.woah.org/#/in-review/6378 ____

Backyard and Farmed Poultry in Karnataka State. Source: WOAH,  https://wahis.woah.org/#/in-review/6366 ____

{England} Small ~53 chicken backyard flock, commercial premises (egg sold). Increased mortality and other clinical signs for HPAI were reported. Samples taken tested positive for HPAI H5N1. Source: WOAH,  https://wahis.woah.org/#/in-review/6373 ____

Backyard and farm-reared poultry in Andhra Pradesh State. Source: WOAH,  https://wahis.woah.org/#/in-review/6344 ____

Abstract The ongoing panzootic of highly pathogenic avian influenza (HPAI) H5 clade 2.3.4.4b has caused widespread poultry mortality and raised concerns about zoonotic pandemics and wildlife conservation . France recently adopted a preventive vaccination strategy , vaccinating domestic ducks with inactivated and mRNA vaccines . This study evaluates the impact of this campaign on reducing HPAI H5 outbreaks. Using predictive modeling based on previous outbreak data, the expected number of outbreaks in 2023-24 without vaccination was significantly higher than the observed cases, indicating a 95.9% reduction attributable to vaccination . These findings suggest that vaccination effectively mitigated the HPAI H5 outbreak in France. Source: BioRxIV,  https://www.biorxiv.org/content/10.1101/2024.08.28.609837v3 ____

 A poultry farm in Khulna Region. Source: WOAH,  https://wahis.woah.org/#/in-review/6351 ____

A poultry farm in Maritime Region. Source: WOAH,  https://wahis.woah.org/#/in-review/6361 ____

{Highland Scotland} Flock of 23 chickens and 4 goose. Increased mortality reported. Samples taken were found positive for HPAI H5N1. Source: WOAH,  https://wahis.woah.org/#/in-review/6357 ____

Abstract High pathogenicity (HP) avian influenza viruses (AIV) generally evolve from low pathogenicity (LP) precursors after transmission from wild birds to chickens (Gallus gallus domesticus) and turkeys (Meleagris gallopavo), causing severe economic losses worldwide. Turkeys are more susceptible to AIV infection than chickens and are considered potential bridging hosts that facilitate the emergence of HPAIV . Beyond the polybasic cleavage site (pCS) in hemagglutinin (HA), little is known about other virulence determinants of HPAIV in these species. In 2015, HPAIV H7N7 and its LP ancestor were isolated from the same chicken farm, which differed by 16 nonsynonymous mutations across all eight gene segments, in addition to the pCS. Here we identify the genetic determinants, including the pCS, that contributed to the HPAIV H7N7 virulence, transmission, replication, and tissue distribution in chickens and turkeys. Notably, the non-structural (NS1) or matrix (M) proteins ’ encoding segments...

A poultry farm in Telangana Region. Source: WOAH,  https://wahis.woah.org/#/in-review/6323 ____

Abstract H5N1 influenza has been circulating in birds from Eurasia and Africa for more than 146 years , but human infection has been sporadic. H5N1 (clade 2.3.4.4b) has recently infected hundreds of species of wild and domestic birds and mammals in North America . Furthermore, as of February 26, 2025, H5N1 has infected 70 humans in the United States , and one infection proved lethal . Furthermore, in attempts to control H5N1 in the United States, 10s of millions of egg-laying chickens have died or been culled . These efforts have led to very high egg prices in the United States. We have developed an analytical bioinformatics and genomics workflow to understand better how H5N1 is circulating in North America and adapting to new host species . Our workflow consists of: 1) Phylogenetic analyses of large viral sequence datasets to identify subclades of viral lineages causing the current outbreaks in humans and farm animals and closely related viral background lineages. 2) Next, we transfer...

 A poultry farm in Centre Region. Source: WOAH,  https://wahis.woah.org/#/in-review/6338 ____

Highly pathogenic avian influenza (HPAI) H7N9 of North American wild bird lineage was detected in a commercial broiler breeder chicken flock in Mississippi . Depopulation of the affected flock is in progress. The USDA Animal and Plant Health Inspection Service (APHIS), in conjunction with State Animal Health and Wildlife Officials, are conducting a comprehensive epidemiological investigation and enhanced surveillance in response to the detection. A commercial broiler breeder premises {in Mississippi}. Clinical signs included increased mortality. Depopulation was completed 13 Mar 2025. Source: WOAH,  https://wahis.woah.org/#/in-review/6340 ____

 A turkeys-for-fattening farm in Bayern Region. Source: WOAH,  https://wahis.woah.org/#/in-review/6328 ____

{England} Commercial turkey fattening unit with 27,658 turkeys. Increased mortality and other clinical signs of HPAI reported. The samples were positive for HPAI H5N1. Source: WOAH,  https://wahis.woah.org/#/in-review/6314 ____