#Genotype Diversity of Highly Pathogenic Avian #Influenza #H5N1 Clade 2.3.4.4b in #Pennsylvania #Poultry During Disease #Outbreak from April 2022 to March 2023

 

Abstract

The 2022 highly pathogenic avian influenza (HPAI) outbreak of H5N1 clade 2.3.4.4b was one of the major avian influenza outbreaks, leading to multiple spillover events infecting domestic and wild bird flocks, as well as mammals. The sustained spread was a result of viral circulation in wild birds across migratory flyways in North America. Pennsylvania has a significant poultry population that supports both retail and live bird markets. The state also features migratory bird stopovers on the Atlantic flyway, increasing exposure to HPAI infections. This study investigates clinical presentation and sequence data from H5N1 clade 2.3.4.4b viruses during the 2022 outbreak in Pennsylvania. Eight different H5N1 clade 2.3.4.4b genotypes were detected (A1, B1.1, B1.2, B1.3, B2.2, B3.3, B3.5, and one minor genotype) during the first year. The earliest detection was genotype A1, a fully Eurasian virus, in commercial poultry in April 2022. All other genotypes identified were reassortants of A1 with North American avian influenza gene segments (denoted with “B”). Genotype B3.3 was a rare genotype prior to the initial spillover into the live bird market system, but remained predominant among backyard flocks in Pennsylvania and surrounding states until September 2023. Genotype B3.3 has not been detected in migratory waterfowl since, suggesting the genotype has waned and is no longer in circulation. This study sheds light on the genotype diversity of H5N1 during the 2022 outbreak in Pennsylvania poultry, contributing to the understanding of virus evolution and its potential impacts.

Source: 

Link: https://www.mdpi.com/1999-4915/18/5/502

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Respirable #Aerosol #Production and Reduction of Avian #Influenza #Transmission #Risk during #Chicken Processing, #Bangladesh

 

Abstract

In Bangladesh, influenza A(H5N1) viruses are endemic in poultry. Processing infected chickens can aerosolize viruses, increasing the risk for human infections. We evaluated particulate matter (PM2.5) mass concentration during slaughtering and defeathering methods used in live bird markets in Bangladesh to identify solutions to reduce aerosol exposure. We slaughtered 675 chickens using cones and barrels with 3 lid types and defeathered 45 chickens using a defeathering machine with 5 lid types. We interviewed 3 slaughterers to understand method preference. For slaughtering, barrels with a solid or star-cut lid reduced PM2.5 mass concentrations by 65%–73% compared with uncovered barrels. For defeathering, machines fully covered by a solid lid or lid with a hole and pivot door reduced PM2.5 mass concentrations by 50% compared with machines with no lid. Slaughterers preferred barrels covered with solid lids and defeathering machines covered with solid or hinged lids. Those methods might reduce aerosol exposure during poultry processing.

Source: 

Link: https://wwwnc.cdc.gov/eid/article/32/4/25-1878_article

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#Serological #Surveillance of Avian #Influenza Virus #H9N2 Subtype in #Occupational Populations Exposed to #Poultry Environment in #China During 2018–2023

 

Abstract

Background

Avian influenza virus (AIV) H9N2 has a major role in the emergence of influenza pandemic. We assessed the risk of AIV H9N2 to the human population and public health.

Method

The hemagglutination inhibition method was used to screen for hemagglutinin antibodies. Microneutralization tests were performed to confirm neutralizing antibodies against the AIV H9N2 subtype. Real-time polymerase chain reaction was conducted to detect the H9 subtype in environmental samples. GraphPad Prism software was used for mapping, and STATA software was used for statistical analysis.

Results

The nationwide seroprevalence among these populations was 0.76%. Seroprevalence was compared across regions, genders, and occupational exposure sites. The seroprevalence rates for males and females showed no significant difference. Significant differences were found across regions and occupational exposure environments (P < .05). The south and southwest regions had the highest seroprevalence rates at 1.58% and 1.38%, respectively. The highest seroprevalence was observed in individuals exposed to live poultry market (1.51%). Significant regional differences in H9 nucleic acid positive rates (NAPRs) were found (P < .05), with the southwest and central regions showing the highest rates at 25.99% and 24.35%, respectively. H9 NAPR in live poultry markets (LPMs), farms, and slaughterhouses varied significantly by region (P < .05).

Conclusions

Poultry-related environments have become a key factor in AIV H9N2 infection among occupational populations. Exposure to LPM showed the highest seroprevalence among occupational groups. The distribution characteristics of H9N2 across different poultry environments increased the risk of infection in occupationally exposed populations.

Source: 

Link: https://academic.oup.com/ofid/article/13/4/ofag144/8537381

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A #Market-Based #Sentinel #Surveillance for an Early #Detection of Viral #Outbreaks

 

Abstract

Mexico has experienced recurrent viral epidemics of substantial intensity, including hyperendemic dengue, COVID-19, and recent reports of avian influenza A (H5N1) infections in birds, which pose an ongoing risk of zoonotic transmission. Mexico was also the location for the earliest detection of the pdmH1N1 virus during the 2009 influenza A pandemic. Under a One Health framework, markets represent a unique opportunity for low-cost virus monitoring at the human-animal interface. Under the hypothesis that these represent sentinel sites for an early virus detection, we implemented a pilot surveillance program at the central market of Merida city, Yucatan, Mexico, considered a regional hotspot for multiple and recent viral outbreaks. Longitudinal sampling was carried out over 11 months at 1-to-6-week intervals from April 2022 to February 2023. We used multi-type surveillance in mosquitoes, live poultry, and wastewater. All samples were screened using RT-qPCR. Positive samples for DENV, SARS-CoV-2 and avian influenza A were further sequenced and analysed under a phylogenetic and epidemiological approach. Through our entomological surveillance, we report the earliest detection of DENV-3 III-B3.2 (genotype III American II lineage, considered a major public health concern in Latin America) in Mexico, overlapping with the resurgence of DENV-3 as the predominant serotype driving the 2023 national epidemic, which showed an increased severity. Through wastewater surveillance, we consistently detect SARS-CoV-2 RNA in wastewater samples, coinciding with the two infection waves officially recorded at a city and state level. Finally, cloacal swabs taken from two juvenile birds at the market suggest that avian influenza A viruses circulated in live poultry sold at the market. These findings show that our market-based surveillance framework is effective for an early detection and monitoring of pathogenic viruses in urban settings, and could complement official epidemiological surveillance in low- and middle-income countries to strengthen early-outbreak warning systems.

Competing Interest Statement

The authors have declared no competing interest.

Funding Statement

This study was supported by the John Fell OUP Research Grant ATD00390 (M.E.Z and M.U.G.K), the Wellcome Infectious Disease Award ?317324/Z/24/Z (M.G.K, H.P.G and M.E.Z), the Secretaria de Ciencia, Humanidades, Tecnología e Inovación award (SECIHTI, Mexico) through the PRONACES Health grant (PRONAII project number 303002, G.S) and the Ciencia Básica y de Frontera programme (CBF2023-2024-3184, M.G.K), and the UKRI Innovation BSRC/EPSRC/NIHR 971557 grant (A.R.S). M.G.K is funded through a Sanger International Fellowship award. M.E.Z is funded by a UCL Rosetrees Excellence Fellowship UCL2024\2. P.M.D was funded through the doctoral program at ‘Posgrado en Ciencias de la Produccion y de la Salud Animal-UNAM’ through the SECIHTI doctoral scholarship. M.U.G.K. acknowledges funding from The Rockefeller Foundation (PC-2022-POP-005), Health AI Programme from Google.org, the Oxford Martin School Programmes in Pandemic Genomics & Digital Pandemic Preparedness, European Union's Horizon Europe programme projects MOOD (#874850) and E4Warning (#101086640), Wellcome Trust grants 303666/Z/23/Z, 226052/Z/22/Z & 228186/Z/23/Z, the United Kingdom Research and Innovation (#APP8583), the Medical Research Foundation (MRF- RG-ICCH-2022-100069), UK International Development (301542-403), the Bill & Melinda Gates Foundation (INV-063472) and Novo Nordisk Foundation (NNF24OC0094346). B.G is further funded by Wellcome Trust grants 303666/Z/23/Z, 226052/Z/22/Z & 228186/Z/23/Z. The contents of this publication are the sole responsibility of the authors and do not necessarily reflect the views of the European Commission or the other funders. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Source: 

Link: https://www.medrxiv.org/content/10.64898/2025.12.22.25342882v1

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#Resurgence of Zoonotic Highly Pathogenic Avian #Influenza #H5N1 Virus in #Cambodia

 

{Excerpts}

To the Editor:

After a decade of no reported human cases, Cambodia faces a resurgence of highly pathogenic avian influenza (HPAI) A(H5N1) virus infections, with an overall mortality of 38%. Cases have occurred primarily in children and adolescents who were exposed to infected poultry (...). From February 2023 through August 2024, a total of 16 infections were detected through the long-standing national influenza-like illness and severe acute respiratory infection surveillance systems, both of which were strengthened by expanded laboratory-testing capacity that was developed during the coronavirus disease 2019 pandemic. All 16 patients reported exposure to sick or dead poultry, and outbreak investigations identified contemporary, genetically similar viruses in poultry collected in or around case households or from active, longitudinal surveillance of live-bird markets. Genomic sequencing revealed an avian origin for all the human infections, and sequences have been publicly shared through the Global Initiative on Sharing All Influenza Data (also known as GISAID).

(...)

Of note, this virus carries genomic signatures (e.g., PB2:E627K) that are linked to enhanced polymerase activity, virulence, and replication capacity in birds and mammals,3 which poses an increased potential risk to the poultry industry as well as an increased potential risk of zoonotic transmission (...)

Source: The New England Journal of Medicine, https://www.nejm.org/doi/full/10.1056/NEJMc2504302?query=TOC&cid=DM2422812_NEJM_Non_Subscriber&bid=-1106918107

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Active #Surveillance for Emerging #Influenza A Viruses – Findings from a #OneHealth Study in #Vietnam’s Live Bird #Markets

 

Highlights

-- We conducted surveillance for influenza A viruses at live bird markets in northern Vietnam.

-- Six different subtypes of influenza A virus were found co-circulating in the markets.

-- Notable genetic mutations were found across many genes.

-- These markets have great potential to generate new pandemic influenza A virus strains.

Abstract

Objectives

Live bird markets (LBMs) in Asia have often been the source of human infections with avian influenza virus (AIV).

Methods

From July 2021 to August 2023, we employed a One Health approach in conducting periodic surveillance for novel influenza A viruses in five LBMs in northern Vietnam. Specimens were studied with egg culture, molecular assays, Sanger sequencing, and next-generation sequencing.

Results

We studied a total of 688 human, avian, and bioaerosol specimens. Among these, 118 (17.2%) were found to have molecular evidence of AIVs. Next-generation sequencing of 92 isolates revealed multiple AIV subtypes, including H4N6 (n=1), H5N1 (n=3), H5N8 (n=6), H6N2 (n=3), H6N6 (n=18), and H9N2 (n=61) and mix infections (n=7). Our H5Nx sequences belonged to the Eurasian lineage clade 2.3.4.4b, while our H6N2 sequences were of group III, H6N6 of group II, and H9N2 of the BJ94-lineage clade 4.6.14.

Conclusions

The relatively high prevalence of AIV, particularly highly pathogenic H5N1 and H5N8 viruses, along with the subtype diversity, frequent co-infections and notable mutations, highlights the urgent need for continued monitoring and control of AIV in Vietnam’s poultry farms and LBMs.

Source: International Journal of Infectious Diseases, https://www.ijidonline.com/article/S1201-9712(25)00354-6/fulltext

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#India - High pathogenicity avian #influenza #H5N1 viruses (#poultry) (Inf. with) - Immediate notification

{Several poultry farms in Uttar Pradesh State.}

HPAI (H5N1) was detected in a Live Bird Market from the environmental sample. Hence no cases were observed.

Source: WOAH, https://wahis.woah.org/#/in-review/6730

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#Genomic #surveillance and #evolution of co-circulating avian #influenza #H5N1 and #H5N8 viruses in #Egypt, 2022–2024

 

ABSTRACT

For over two decades, avian influenza virus (AIV) has significantly impacted the Egyptian poultry population, with multiple subtypes and genotypes contributing to significant economic and agricultural losses. As part of an ongoing national surveillance effort, this study aimed to monitor and genetically characterize AIV circulation across various poultry sectors in Egypt. Between 2022 and 2024, a total of 446,790 swab samples were collected, representing commercial farms (n = 25,057), backyard flocks (n = 403), and live bird markets “LBM” (n = 1250) to assess the prevalence and genetic diversity of circulating AIV strains. A total of 173 sampling units were found positive for high pathogenicity (HP) AIV H5, including farms (n = 17), backyards (n = 11), and LBMs (n = 145). The HPAIV of H5N8 subtype was dominant (n = 75) over the H5N1 (n = 27) subtypes among all sectors and bird species (chickens, ducks, turkeys). Whole genome sequence analysis of positive H5 samples revealed high similarity with HPAIVs of clade 2.3.4.4b, which has been confirmed phylogenetically. Two distinct subtypes H5N1 (EA-2021-AB genotype) and H5N8 (EA-2020-A genotype) were identified, with two variants detected within the H5N8 viruses. Evolutionary analyses indicate that Egyptian H5N8 viruses are under strong selection pressure and exhibit a higher nucleotide substitution rate compared to the Egyptian H5N1 viruses of clade 2.3.4.4b. With the evolving HPAI H5 virus’s situation in different locations around the globe, including Egypt, this study underlines the importance of active surveillance in the timely detection of emerging AIV genotypes, monitoring virus evolution, and refining risk assessments.

Source: Emerging Microbes and Infections, https://www.tandfonline.com/doi/full/10.1080/22221751.2025.2562046#abstract

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Analysis of the #surveillance results of avian #influenza in the external #environment of #Huzhou city from 2017 to 2023

Abstract

Background

Avian influenza is an infectious disease of birds caused by the influenza A virus, which can infect a variety of domestic,wild birds and even cross the species barrier and infect humans.To understand the contamination of avian influenza virus in the external environment of poultry in Huzhou City from 2017 to 2023 and to assess the risk of human infection with avian influenza.

Methods

A total of 3,400 environmental specimens from five types of venues in Huzhou City were collected and tested for influenza A virus nucleic acid using fluorescent reverse transcription polymerase chain reaction (RT-PCR).

Results

From 2017 to 2023, with 15.44% overall positive rate of influenza A virus. The predominant subtype of avian influenza virus was H9 (accounting for 54.67%). The peak of positive influenza virus detection rates occurred in winter and spring seasons every year. The venue with highest positive rate was poultry slaughtering and processing plants (41.83%), followed by urban and rural live poultry markets (35.48%); among all types of specimens, the highest positive rate was detected in swab specimens from the surfaces of poultry slaughtering or display tables (47.37%), followed by wastewater from poultry washing (45.83%), and surfaces of cages (27.65%).

Conclusion

The contamination of avian influenza virus in the poultry environment in Huzhou City is relatively severe, with diverse subtypes. There is a potential risk of human infection with avian influenza virus, and real-time monitoring of avian influenza virus in the poultry environment needs to be strengthened.

Source: PLoS One, https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0326382

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Environmental #monitoring and spatiotemporal #trend #analysis of avian #influenza virus in #Xinjiang, 2021-2023

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% of positive samples. Significant differences in detection rates were observed across different years, regions, sample types, and monitoring sites. Temporally, the positive rate showed an upward trend from 2021 to 2023, with higher positive rates in January and July. Geographically, Aksu, Turpan, and Ili were identified as high-risk areas. Urban and rural live poultry markets had the highest positivity rate (24.31%), and poultry drinking water, cage surfaces, and cleaning wastewater samples showed relatively high detection rates. Kriging analysis revealed several high-risk zones for virus presence.

Conclusion

This study provides crucial information for understanding the epidemiological characteristics of avian influenza virus in the external environment of Xinjiang. The H9 subtype was found to be predominant, with notable seasonal and regional variations. Live poultry markets were identified as key risk sites. These findings underscore the need for continuous surveillance and offer theoretical support for developing targeted prevention and control strategies. However, the limited scope of monitoring suggests that broader and longer-term studies are needed to better understand subtype interactions and epidemic risks.

Source: BMC Infectious Diseases, https://bmcinfectdis.biomedcentral.com/articles/10.1186/s12879-025-11155-3

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Clade 2.3.4.4b Highly pathogenic #H5N1 #influenza viruses from #birds in #China replicate effectively in #bovine cells and pose potential public health #risk

Abstract

In February 2024, H5N1 highly pathogenic avian influenza viruses (HPAIVs) of clade 2.3.4.4b were first reported in dairy cows in the USA. Subsequent multiple outbreaks on dairy farms and sporadic human infections have raised substantial public health concerns. In the same year, four H5N1 HPAIVs of clade 2.3.4.4b were isolated from ducks and geese in live poultry markets (LPMs) spanning seven provinces in China. Evolutionary analysis demonstrated that these viruses had undergone two genetic reassortments with H5 influenza viruses from wild birds in different countries. Except for 565/H5N1, the other three viruses exhibited over 99% genetic homology with avian-origin H5N1 HPAIVs from South Korea and Japan. Notably, 571/H5N1 demonstrated high replication efficiency in bovine-derived cells, particularly in bovine mammary epithelial (MAC-T) cells, and caused 16.7% (1/6) mortality in mice at a dose of 10⁵ EID₅₀/50 μL, indicating its zoonotic potential. Given the potential cross-species transmission risk of H5N1 HPAIVs to cattle herds, we collected 228 serum samples from 12 cattle farms across five provinces and conducted serological testing to investigate seroprevalence of H5N1 HPAIVs in Chinese cattle herds. All tested samples were negative, indicating no widespread infection in the sampled cattle populations. However, infections in cattle from other regions cannot be ruled out. Nevertheless, due to the high mutability of H5N1 HPAIVs, enhanced surveillance of avian influenza viruses is critical to ensure timely responses to potential outbreaks.

Source: Emerging Microbes and Infections, https://www.tandfonline.com/doi/full/10.1080/22221751.2025.2505649

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Characterization of the avian #influenza viruses #distribution in the #environment of live #poultry #market in #China, 2019–2023

Abstract

Background

The prevalence and transmission of avian influenza viruses (AIVs) in the live poultry market (LPM) is a serious public health concern. This study was to investigate the prevalence of different subtypes of avian influenza viruses in environment of LPM, and to analyze the differences and seasonality of the nucleic acid positive rate (NAPR) of A type, H5, H7, and H9 subtypes in feces, sewage, drinking water, breeding cages, and chopping boards.

Methods

Feces, breeding cages swabs, drinking water, sewage and chopping boards swabs were collected from live poultry market during 2019–2023 from southern and northern China. Real-time PCR was used to screen for virus subtypes. Viruses were isolated, and deep sequencing was performed to obtain whole-genome sequences. Chi-square test was used for statistical analysis of categorical variable, GraphPad Prism software were used to construct graphs.

Results

A total of 64,599 environmental samples were collected from live poultry markets in the southern China and northern China between 2019 and 2023. The average NAPR of the A type was significantly higher in the samples collected from the southern China than in those collected from the northern China (P < 0.05). The NAPR of H5, H7, and H9 subtypes carried by the five types of environmental samples in the southern China were significantly different (P < 0.05), and a higher NAPR was detected in chopping boards (10.84%), breeding cages (0.28%), and drinking water (40.97%) respectively. The average NAPR of the H9 and H5 subtypes displayed seasonality, reaching a peak in January and February in the southern China, while the peak of the H9 subtype was from October to February in the northern China. A total of 19 subtypes were identified. The H5 subtype significantly decreased, the H7 subtype was almost undetectable, and other subtypes, such as the H3 subtype, increased.

Conclusions

The highly pathogenic H5 subtype has significantly decreased in the live poultry market in China since 2022. However, the proportion of some subtypes, such as the H3 subtype, with low pathogenicity to poultry, has increased, while the H9 subtype remains at a high level. It must be noted that these low pathogenic avian influenza viruses often have no obvious symptoms, can circulate asymptomatically in infected poultry, and are highly pathogenic to humans. Our findings provide insights into the control and prevention of avian influenza viruses and the risk of pandemics associated with avian influenza viruses in the live poultry market.

Source: Infectious Diseases of Poverty, https://idpjournal.biomedcentral.com/articles/10.1186/s40249-025-01304-w

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