ETIDIOH - NEW

ABSTRACT Influenza A (H3N2) viruses are historically responsible for the 1968 Hong Kong flu pandemic. Since then, H3N2 has continued to circulate as a seasonal influenza virus in humans. Public health concerns were raised in 2022 when human infections with novel reassortant H3N8 influenza viruses originating from chickens were first reported in China . Here, we conducted a systematic surveillance of H3 avian influenza viruses (AIVs) circulating in poultry and assessed the public health risk of emergent H3 reassortants. We found that H3 AIVs were prevalent in both ducks and chickens . Notably, in December 2022, a novel chicken-derived H3N3 subtype virus was identified, which gradually replaced the previously predominant H3N8 virus and became prevalent in chickens. Genetic analysis demonstrated that the novel H3N3 virus is a triple-reassortment strain with the H3 gene segment from chicken H3N8 virus, the N3 gene segment from the H10N3 virus , and internal gene segments derived from H9N2 ...

A small commercial flock of 69 chickens, 23 ducks and 5 geese. Increased mortality reported in chickens as well as a drop in egg production in the ducks. Samples were taken and tested positive for HPAI H5N1. Location:  Kirklees, West Yorkshire, England. Source: WOAH,  https://wahis.woah.org/#/in-review/6552 ____

Abstract Highly pathogenic avian influenza causes substantial poultry losses and zoonotic concerns globally . Duck vaccination against highly pathogenic avian influenza began in France in October 2023. Our assessment predicted that 314–756 outbreaks were averted in 2023–2024, representing a 96%–99% reduction in epizootic size, likely attributable to vaccination. Source: US Centers for Disease Control and Prevention,  https://wwwnc.cdc.gov/eid/article/31/7/24-1445_article ____

Abstract Since 2021, the novel H10N3 has caused four cases of human infection in China, the most recent of which occurred in December 2024 , posing a potential threat to public health. Our previous studies indicated that several avian H10N3 strains are highly pathogenic in mice and can be transmitted between mammals via respiratory droplets without prior adaptation. By analyzing the genome sequence , we found that these H10N3 viruses carry the PB2-E627V mutation , which is becoming increasingly common in several subtypes of avian influenza viruses (AIV); however, its mechanism in mammalian adaptation remains unclear. Using a reverse genetics system , we investigated the role of PB2-E627V in the adaptation of H10N3 to mammals and poultry. Our findings demonstrate that the PB2-E627V mutation is critical for the high pathogenicity of novel H10N3 in mice and its ability to be transmitted through the air among mammals . Additionally, we found that the role of PB2-627 V in promoting AIV adap...

Abstract Nationwide surveillance of avian influenza viruses (AIVs) in live poultry markets across China has occurred since 2014, providing a resource for AIV prevalence and genetic diversity studies . Here we report that 3,237 of 18,425 samples from poultry were AIV positive (17.57%) between 2019 and 2023, with H9N2 being the dominant subtype . We developed an automated phylogeny-based nomenclature system to classify genetic clades of the dominant H9N2 lineage, the BJ94 lineage. Using this model, we found that ten haemagglutinin (HA) sub-subclades cocirculated in poultry and showed antigenic variation. In addition, 99.46% and 96.17% of H9N2 AIVs in 2021–2023 possessed human-receptor binding-related HA-L226 and human MxA-resistance-related NP-N52 mutations , respectively. H9N2 strains with these two mutations preferred human-type receptors and increased replication in human cells in vitro, regardless of the presence of PB2-V/K/E627. Moreover, H9N2 AIVs containing HA-L226, PB2-V/K627 and...

HPAI H5N1 confirmed in backyard poultry farm with approx. 190 birds (laying hens). Susupicion date 27/05/2025 - some birds with neurological signs, one dead. Laboratory diagnosis confirmed at the Latvian National Reference Laboratory for avian influenza. Source: WOAH,  https://wahis.woah.org/#/in-review/6528 ____

Highlight Brazil’s first confirmed H5N1 outbreak in commercial poultry marks a critical shift in South America’s avian influenza landscape. The event calls for strengthened coordination between animal and human health sectors, improved border surveillance, and early-warning systems to reduce zoonotic risk in regions with growing poultry production and international connectivity. Source: Journal of Travel Medicine,  https://academic.oup.com/jtm/advance-article-abstract/doi/10.1093/jtm/taaf050/8153894?redirectedFrom=fulltext ____

Abstract Infectious bronchitis virus (IBV) and low-pathogenic avian influenza virus (LPAIV) H9N2 are commonly identified in poultry , individually or in association with other pathogens. This study monitored 183 broiler farms affected by respiratory diseases across seven regions of Morocco from January 2021 to December 2023. Among these farms, 87.98% were vaccinated against IBV, while 57.92% were against AI H9N2 . Abnormally high mortality rates were observed in 44.26% of the farms, with 24.69% of cases attributed to IBV, 50.62% to LPAI H9N2, and 13.58% due to coinfection with both IBV and H9N2 . RT-PCR analysis of tissue samples and cloacal and tracheal swabs collected from 183 broiler farms revealed that 33.33% were positive for IBV and 34.97% for H9N2. Coinfection by IBV and H9N2 was detected in 12.57% of cases , peaking at 17% in 2022. Co-infected flocks exhibited severe clinical signs and lesions, such as reduced food consumption, diarrhea, and renal issues. The predominant lesion...

Abstract Background Avian influenza, a significant threat to public health , requires monitoring for the development of control strategies. This study aims to analyze the spatiotemporal distribution of avian influenza virus in the external environment of Xinjiang from 2021 to 2023, to enhance understanding of its transmission patterns and provide a scientific basis for public health response measures. Methods A total of 3913 avian-related environmental samples were collected from nine monitoring areas in Xinjiang . Sample types included poultry drinking water, meat cutting boards, cage surfaces, feces, and wastewater. Real-time RT-PCR was used to detect nucleic acid for H5, H7, and H9 subtypes. Data were statistically analyzed using Excel and SPSS, and spatial distribution was visualized through Kriging interpolation using ArcGIS. Results Among the collected samples, 810 tested positive , with an overall positivity rate of 20.70%. The H9 subtype was predominant , accounting for 85.43% ...

Abstract Avian influenza virus (AIV) is a significant global concern, causing widespread mortality in wild birds, domestic poultry and most recently wild and domestic mammals . This study presents a retrospective analysis of AIV detections in the Republic of Ireland . Data was sourced from official surveillance databases, peer-reviewed literature and grey literature sources. Spatio-temporal, host-specific and subtype patterns were assessed using descriptive statistics, chi-square tests, linear regression and kernel density estimations. A total of 2,888 confirmed AIV detections were recorded from 25 of Ireland's 26 counties . Wild birds accounted for 98.7% of detections, with domestic birds comprising 1.3% and two detections in foxes . H5N1 was the most prevalent subtype (96.7%) followed by H5N8 and H6N1 . Spatial clustering was observed in urban areas, particularly Dublin . The highest seasonal peak occurred during summer, contrasting with traditional winter-associated patterns. Se...

Abstract Since 2015, French poultry production is threatened almost every year by a reintroduction of highly pathogenic avian influenza H5 viruses . The duck sector was the most concerned by this crisis but other sectors such as broiler, layer and turkey were also affected by outbreaks. The objective of this work was to assess the risk of highly pathogenic avian influenza H5 virus transmission from one farm to another within the French broiler and layer production network. This study used the WOAH risk assessment framework . After drawing up a scenario tree of virus transmission from one farm to another, data were collected through a literature review or through experts' elicitation. Three questionnaires were developed according to the experts' field of expertise: avian influenza, broiler and layer sectors. The experts' estimates were combined using a beta distribution weighted by their confidence level. A Monte Carlo iteration process was used to combine the different prob...

Abstract Avian influenza (AI) is a highly contagious viral disease affecting poultry and wild water birds , posing significant global challenges due to its high mortality rates and economic impacts. Highly pathogenic avian influenza (HPAI) outbreaks , particularly those caused by H5N1 and its variants , have surged since their first occurrence in 1959. The HPAI H5N1 clade 2.3.4.4b viruses have notably expanded its geographical reach, affecting numerous countries, diverse avian species, and now wild and domestic mammals . Using an ecological niche modelling approach, this study aims to elucidate the environmental factors associated with the increased HPAI H5 cases since 2020, investigate potential shifts in ecological niches , and predict new areas suitable for local viral circulation. Focusing on H5N1 and H5Nx strains, we have developed ecological niche models for HPAI case in both wild and domestic birds while considering two distinct periods: 2015-2020 and 2020-2022. Key environmenta...

ABSTRACT Long-distance migratory ducks play a critical role in the maintenance and dissemination of A(H5N1) viruses . Comparative pathogenicity studies were conducted on blue-winged teal (BWTE; Anas discors) using three distinct genotypes of A(H5N1) clade 2.3.4.4b viruses (A1, B1.3, and B4.1) isolated from wild ducks in Canada . Twenty-four hours post-intranasal infection of BWTE, contact turkeys and chickens were introduced into each of the groups to evaluate viral transmission. The levels of viral shedding in BWTE increased from 3 to 7 days post-infection (dpi) and continued at lower levels until 14 dpi. The A1 genotype virus (MALL/NS/22) was found to be the least pathogenic to BWTE compared to the reassortant genotypes, B4.1 (RBME/BC/22) and B1.3 (BWTE/MB/22). The B1.3 genotype was the most virulent to BWTE and caused 66.7% mortality compared to 12.5% mortality caused by the B4.1 genotype. The extent of transmission from infected BWTE to contact turkeys and chickens showed variation...

  On the 19th of May, an official veterinary doctor was called to the farm due to suspected influenza, as there was an increase in mortality within the animals. On the same day, samples were taken and sent to the Bulgarian National Laboratory for Avian Influenza, where, on the 20th of May, it was confirmed that the farm was affected by a highly pathogenic avian influenza virus. Source: WOAH,  https://wahis.woah.org/#/in-review/6490 ____

Abstract Avian influenza viruses continue to challenge poultry and human health ; therefore, careful surveillance and evaluation of emerging viruses are important for animal disease control and human influenza pandemic preparedness . In this study, we detected a series of H3N3 subtype avian influenza viruses in chickens , pigeons, and ducks during our routine surveillance and diagnosis between September 2022 and May 2023. We performed extensive analyses to fully understand the origins of these viruses and their risk to animals and humans. We found that the viruses were complex reassortants ; the viruses from chickens and pigeons carry genes mainly derived from H3N8 viruses and H10N3 viruses , whereas the two duck viruses were reassortants of duck and wild bird viruses. The chicken and pigeon , but not duck, viruses replicated in multiple organs of chickens and were shed for up to 13 days, but none caused disease or death. Six of the viruses tested all bound to both avian- and human-typ...

Abstract H5Nx clade 2.3.4.4b high-pathogenicity avian influenza viruses (HPAIVs) have decimated wild bird and poultry populations globally since the autumn of 2020. In the United Kingdom (UK) and in continental Europe , the H5N8 subtype predominated during the first epizootic wave of 2020/21 , with few detections of H5N1. However, during the second (2021/22) and third (2022/23) epizootic waves, H5N1 was the dominant subtype. The rapid shift in dominance from H5N8 to H5N1 was likely driven by a combination of virological, immunological, and/or host-related factors. In this study, we compared viral fitness and immunological responses in ducks , a key reservoir species, using dominant genotypes of H5N1 (genotype AB) and H5N8 (genotype A) from the second wave. While viral shedding dynamics were similar for both viruses, H5N8 was more pathogenic . Antigenic analysis of post-infection duck sera revealed that the haemagglutinin (HA) protein was antigenically similar across clade 2.3.4.4b H5 H...

Abstract The interspecies transmission of avian influenza viruses remains a significant public health concern. H6 viruses have gained attention following the first human infection by a chicken-origin H6N1 virus (A/Taiwan/02/2013, Hu/13), highlighting their zoonotic potential . To understand the evolutionary trajectory and mammalian adaptation of this Taiwan lineage , we compared two avian isolates (A/Chicken/Taiwan/CF19/2009, Ck/09; A/Chicken/Taiwan/2267/2012, Ck/12) and Hu/13 in vitro and in vivo. Hu/13 exhibited enhanced replication in MDCK cells , producing larger plaques and higher viral titers than Ck/09 and Ck/12. In BALB/c mice , Hu/13 demonstrated the highest pathogenicity and mortality , followed by Ck/12, while Ck/09 induced minimal morbidity. Hu/13 and Ck/12 replicated efficiently in respiratory tissues , eliciting robust cytokine responses and severe pulmonary lesions . In ferrets , Hu/13 showed relatively efficient transmission , infecting all direct physical-contact and t...

Abstract Highly pathogenic avian influenza (HPAI) A/H5N1 viruses threaten animal and human health worldwide . The first documented cases in the Middle East were reported in 2005 ; however, despite extensive phylogenetic studies , there is limited information on the transmission dynamics of the virus within this region. We analyzed HA and NA gene sequences from various hosts to address this gap and to understand the virus’s spread and evolution in the Middle East. We hypothesized that H5N1 transmission exhibits host-specific or geographically influenced clade structures in this region . This study traced transmission pathways of HPAI A/H5N1 through a phylogenetic and amino acid sequence analysis of HA and NA gene segments from isolates across different hosts in Middle Eastern countries, using the MUSCLE algorithm for alignments and MEGA11 software for phylogenetic analysis. Sequences were selected from NCBI’s virus database based on geographic and host diversity, including those from bi...

  Increased mortality of poultry, clinical signs, commercial holding of pheasants, hens, ducks, geese, peacocks. Source: WOAH,  https://wahis.woah.org/#/in-review/6486 ____

  The Official Veterinary Services (OVS) received a notification of acute mortality, neurological and digestive signs in a breeder farm . From the start of the OVS investigation, the premise was quarantined, including suspension of the movement of birds and products. Laboratory analysis identified H5N1 virus clade 2.3.4.4b. OVS is conducting an epidemiological investigation of the event and implementing the restrictions and measures in accordance with the National Contingency Plan for high pathogenicity avian influenza (HPAI). Source: WOAH,  https://wahis.woah.org/#/in-review/6484 ____