Search

Highly pathogenic avian influenza (HPAI) poses a significant threat to animal and public health, with outbreaks occurring globally. HPAI poses significant challenges due to its high mortality rate and public health concerns, with outbreaks spreading globally since the emergence of the H5N1 virus in 2003. In Japan, HPAI outbreaks have been particularly prevalent during autumn and winter seasons, with the 2022-2023 winter experiencing the most severe outbreak to date. However, limited research has directly examined the association between HPAI outbreaks and weather conditions in Japan. Here we show that specific weather conditions are associated with an increased risk of HPAI outbreaks on poultry farms in Japan. By analyzing databases of HPAI cases and meteorological data from 2020-2023, we found that higher average air temperatures two to three weeks prior, lower average wind speeds four weeks prior, and longer sunlight hours two and four weeks prior to outbreaks were significantly associated with increased risk of HPAI outbreaks in Japan. These results suggest that weather may influence environmental survival and transmission of the virus, as well as patterns of wild bird movement that could seed new outbreaks. These findings enhance our understanding of the factors influencing HPAI transmission dynamics and highlight the importance of integrating weather forecasts into disease surveillance and prevention strategies. [ABSTRACT FROM AUTHOR]

In July 2023, cases of highly pathogenic avian influenza (HPAI) were reported at 2 shelters for stray cats in Seoul, South Korea. The cause of infection was suspected to be improperly sterilized raw food made from domestic duck meat, which was manufactured in South Korea. All viruses isolated from cats at the shelters and from the raw food belonged to HPAI A(H5N1) clade 2.3.4.4b. The gene constellation of all viruses was most similar to that of viruses isolated in Korea in November 2022. Of note, the viruses isolated from infected cats harbored mutations E627K or D701N in polymerase basic 2, which are indicative of adaptation to mammals. Postmortem examination revealed systemic pathologic lesions and the presence of widespread virus in different tissues. Thus, consumption of raw duck meat contaminated with HPAI virus likely caused systemic symptoms and death in cats, indicating the introduction of mammal-adapted mutations of the virus.

Testing of ducks in Tennessee, United States, before introduction of highly pathogenic influenza A(H5N1) virus demonstrated a high prevalence of antibodies to influenza A virus but very low prevalence of antibodies to H5 (25%) or H5 and N1 (13%) subtypes. Antibody prevalence increased after H5N1 introduction.

Australia is a sink for low pathogenicity avian influenza viruses, with isolated circulation occurring on the continent. We report the incursion of a Eurasian low pathogenicity avian influenza H5 virus into Australia. This report benefits surveillance and diagnostic work because of the risk and current absence of highly pathogenic avian influenza A(H5N1).

Highly pathogenic strains of avian influenza (HPAI) devastate poultry flocks and result in significant economic losses for farmers due to high mortality, reduced egg production, and mandated euthanization of infected flocks. Within recent years, HPAI outbreaks have affected egg production flocks across the world. The H5N2 outbreak in the US in 2015 resulted in over 99% mortality. Here, we analyze sequence data from chickens that survived (42 cases) along with uninfected controls (28 samples) to find genomic regions that differ between these two groups and that, therefore, may encompass prime candidates that are resistant to HPAI. Blood samples were obtained from survivors of the 2015 HPAI outbreak plus age and genetics-matched non-affected controls. A whole-genome sequence was obtained, and genetic variants were characterized and used in a genome-wide association study to identify regions showing significant association with survival. Regions associated with HPAI resistance were observed on chromosomes 1, 2, 5, 8, 10, 11, 15, 20, and 28, with a number of candidate genes identified. We did not detect a specific locus which could fully explain the difference between survivors and controls. Influenza virus replication depends on multiple components of the host cellular machinery, with many genes involved in the host response. [ABSTRACT FROM AUTHOR]

Avian influenza (AI) is a viral infection that profoundly affects global poultry production. This study aimed to identify the spatial and temporal factors associated with AI in Thailand, using a geographic information system (GIS)–based multi‐criteria decision analysis (MCDA) approach. We discovered that high‐risk areas for AI were primarily concentrated in the central and lower northern regions of the country, with fewer occurrences in the northeastern and southern regions. Model validation using historical outbreak data showed moderate agreement (AUC = 0.60, 95% CI = 0.58–0.61). This study provides valuable insights for planning national AI surveillance programs and aiding in disease prevention and control efforts. The efficiency and effectiveness of disease surveillance at the national level can be improved using this GIS‐based MCDA, in conjunction with temporal risk factor analysis. [ABSTRACT FROM AUTHOR]

Since early 2024, a multistate outbreak of highly pathogenic avian influenza H5N1 has been affecting dairy cattle in the USA. The influenza viral RNA concentrations in milk make it an ideal matrix for surveillance purposes. However, viral RNA detection in multi-component fluids such as milk can be complex, and optimization of influenza detection methods is thus required. Raw bulk tank milk and mastitis milk samples were artificially contaminated with an avian influenza strain and subjected to five extraction methods. HCoV-229E and synthetic RNA were included as exogenous internal process controls. Given the high viral load usually observed in individual raw milk samples, four out of five tested methods would enable influenza detection in milk with normal texture, over a time window of at least 2 weeks post-onset of clinical signs. Nevertheless, sample dilution 1:3 in molecular transport medium prior to RNA extraction provided the best results for dilution of inhibitory substances and a good recovery rate of influenza RNA, that reached 12.5 ± 1.2% and 10.4 ± 3.8% in two independent experiments in bulk milk and 11.2 ± 3.6% and 10.0 ± 2.9% on two cohorts of mastitis milk samples. We have also shown compatibility of an influenza RT-qPCR system with synthetic RNA detection for simultaneous validation of the RNA extraction and RT-qPCR processes. [ABSTRACT FROM AUTHOR]

Highly pathogenic avian influenza (HPAI) is a highly contagious viral disease that represents a significant threat to poultry production worldwide. Variants of the HPAI virus (HPAIV) H5A/Goose/GuangDong/1/96 (H5 Gs/GD/96) lineage have caused five intercontinental epizootic waves, with the most recent, clade 2.3.4.4b, reaching Argentina in February 2023. Initially detected in wild birds, the virus quickly spread to backyard and commercial poultry farms, leading to economic losses, including the loss of influenza-free status (IFS). By March/April 2023 the epidemic had peaked and vaccination was seriously considered. However, the success of strict stamping-out measures dissuaded the National Animal Health Authority (SENASA) from authorizing any vaccine. Suspected cases sharply declined by May, and the last detection in commercial poultry was reported in June. The effective control and potential eradication of HPAIV in Argentina were due to SENASA's early detection and rapid response, supported by private companies, veterinarians, and other stakeholders. Stamping-out measures have been effective for virus elimination and reduced farm-to-farm transmission; however, as the virus of this clade may remain present in wild birds, the risk of reintroduction into poultry production is high. Therefore, maintaining continuous active surveillance will be crucial for promptly detecting any new HPAIV incursion and taking appropriate action to contain virus dissemination. [ABSTRACT FROM AUTHOR]

The multisource surveillance tool (MUST) is a platform for collecting, gathering, and visualizing different sources of information related to health events and highly pathogenic avian influenza in mammals (HPAIM). MUST-AI constitutes the first part of the MUST tool, which centralizes health information relating to cases of HPAIM since January 1, 2021, and comes from 3 different notification sources, an official notification source confirmed by public health institutions (i.e., WAHIS) and two other alternative unofficial sources that collect events from online media (PADI-web) and expert networks (ProMED). Owing to the use of natural language processing (NLP) algorithms, HPAIM events are represented on an interactive map associated with a graph that represents their distribution over a given time interval. This paper presents new tools and approaches for data fusion and experiments for selecting data to integrate into MUST that are related to HPAIM events. [ABSTRACT FROM AUTHOR]

Quantifying numbers of birds released for shooting is an important step towards understanding the ecological consequences of releasing. For Mallard, this has become urgent with the recent rise of Highly Pathogenic Avian Influenza (HPAI). By adapting a previous approach to generating UK-level estimates of numbers of huntable birds shot using the Game and Wildlife Conservation Trust's National Gamebag Census (Aebischer NJ (2019) Fifty-year trends in UK hunting bags of birds and mammals, and calibrated estimation of national bag size, using GWCT's National Gamebag Census. Eur J Wildl Res 65:64. https://doi.org/10.1007/s10344-019-1299-x), the number of Mallards released annually in the UK rose from 870,000 in 2004 to 1.3 million in 2022. Mallards were shot at just over half of NGC sites; of those a fifth released Mallards for shooting, accounting for 87% of the total Mallard bag in 2022. In that year, mean release size was 792 (median 300) and mean release density was 1.39 birds/ha (median 0.52). One fifth of release sites released over 1000 birds each, mostly in southern England and Scotland, corresponding to just 2% of UK shoots. The low percentage combined with low dispersal of released Mallards suggests that scope for them to spread disease is limited, and that any spread is more likely to occur by infection from and transmission to wild birds on passage than from dispersed released ducks. [ABSTRACT FROM AUTHOR]

In March 2024, clade 2.3.4.4b H5N1 highly pathogenic avian influenza virus (HPAIV) was detected in dairy cattle in the US, and it was discovered that the virus could be detected in raw milk. Although affected cow’s milk is diverted from human consumption and current pasteurization requirements are expected to reduce or eliminate infectious HPAIV from the milk supply, a study was conducted to characterize whether the virus could be detected by quantitative real-time RT-PCR (qrRT-PCR) in pasteurized retail dairy products and, if detected, to determine whether the virus was viable. From 18 April to 22 April 2024, a total of 297 samples of Grade A pasteurized retail milk products (23 product types) were collected from 17 US states that represented products from 132 processors in 38 states. Viral RNA was detected in 60 samples (20.2%), with qrRT-PCRbased quantity estimates (non-infectious) of up to 5.4log1050% egg infectious doses per mL, with a mean and median of 3.0log10/mL and 2.9log10/mL, respectively. Samples that were positive for type A influenza by qrRT-PCR were confirmed to be clade 2.3.4.4 H5 HPAIV by qrRT-PCR. No infectious virus was detected in any of the qrRT-PCR-positive samples in embryonating chicken eggs. Further studies are needed to monitor the milk supply, but these results provide evidence that the infectious virus did not enter the US pasteurized milk supply before control measures for HPAIV were implemented in dairy cattle. IMPORTANCE Highly pathogenic avian influenza virus (HPAIV) infections in US dairy cattle were first confirmed in March 2024. Because the virus could be detected in raw milk, a study was conducted to determine whether it had entered the retail food supply. Pasteurized dairy products were collected from 17 states in April 2024. Viral RNA was detected in one in five samples, but infectious virus was not detected. This provides a snapshot of HPAIV in milk products early in the event and reinforces that with current safety measures, infectious viruses in milk are unlikely to enter the food supply. [ABSTRACT FROM AUTHOR]

From December 2023 to March 2024, a surveillance program aiming to detect Highly Pathogenic Avian Influenza (HPAI) H5N1 was conducted on Antarctica territories, specifically at Fildes Peninsula (King George Island, Maritime Antarctic), and James Ross Island. At Fildes Peninsula, samples from marine birds and mammals were collected from four accessible sampling locations with significant animal colonies: Ardley Island, hosting a large concentration of Gentoo penguins (Pygoscelis papua); Ardley Cove, where small groups of likely non-breeding Chinstrap penguins (Pygoscelis antarcticus) were present; seal haul-out sites of Southern elephant (Mirounga leonina) and Weddell (Leptonycotes wedellii); and, a nesting site of Southern giant petrels (Macronectes giganteus). Additionally, six samples were collected from five dead skuas near the Lachman lakes on James Ross Island (63.7989S, 57.8105W) on March 3, 2024. Despite collecting a total of 943 samples from Fildes Peninsula, all results tested negative for HPAI, and no animals displayed clinical signs or behaviors consistent with HPAI infection. However, all skua samples from James Ross Island tested positive for HPAI H5N1 clade 2.3.4.4 by specific real-time RT-PCR reactions, confirming the first recorded HPAI-related mortality event in Antarctica (south of 60°S), specifically in skuas. Further research is necessary to genetically characterize the virus and better understand the role of skuas in viral dissemination in Antarctica.

High pathogenicity avian influenza (HPAI) virus H5N1 first emerged in Bangladesh in 2007. Despite the use of vaccines in chickens since 2012 to control HPAI, HPAI H5Nx viruses have continued to infect poultry, and wild birds, resulting in notable mass mortalities in house crows (Corvus splendens). The first HPAI H5Nx viruses in Bangladesh belonged to clade 2.2.2, followed by clade 2.3.4.2 and 2.3.2.1 viruses in 2011. After the implementation of chicken vaccination in 2012, these viruses were mostly replaced by clade 2.3.2.1a viruses and more recently clade 2.3.4.4b and h viruses. In this study, we reconstruct the phylogenetic history of HPAI H5Nx viruses in Bangladesh to evaluate the role of major host species in the maintenance and evolution of HPAI H5Nx virus in Bangladesh and reveal the role of heavily impacted crows in virus epidemiology. Epizootic waves caused by HPAI H5N1 and H5N6 viruses amongst house crows occurred annually in winter. Bayesian phylodynamic analysis of clade 2.3.2.1a revealed frequent bidirectional viral transitions between domestic ducks, chickens, and house crows that was markedly skewed towards ducks; domestic ducks might be the source, or reservoir, of HPAI H5Nx in Bangladesh, as the number of viral transitions from ducks to chickens and house crows was by far more numerous than the other transitions. Our results suggest viral circulation in domestic birds despite vaccination, with crow epizootics acting as a sentinel. The vaccination strategy needs to be updated to use more effective vaccinations, assess vaccine efficacy, and extension of vaccination to domestic ducks, the key reservoir.

ABSTRACTOn 13 October 2023, the National Directorate for Livestock Development in Mozambique was notified of a suspected outbreak of avian influenza in commercial layers. Samples were screened by real-time and conventional RT–PCR and were positive for both H7 and N6. Full genome sequences were obtained for three representative samples. Sequence analysis of the H7 cleavage site confirmed that the viruses were highly pathogenic (i.e. 333- PEPPKGPRFRR/GLF-346). In addition, the H7 and N6 sequences were highly similar (from 99.4-99.5% and 99.6-99.7% for the HA gene and the NA gene, respectively) to the sequences of a H7N6 virus identified in the Republic of South Africa in May 2023 indicating a similar origin of the viruses. The identification of H7N6 HPAIV in Mozambique has important implications for disease management and food security in the region.

The highly pathogenic avian influenza H5 2.3.4.4 and 2.3.2.1c subclades have distinct antigenic properties and are responsible for the majority of human infections. Therefore, it is essential to understand the processes by which antibodies inhibit these subclade viruses to develop effective therapies and vaccines to prevent their escape from neutralizing antibodies. Herein, we report the epitopes of two specific monoclonal antibodies (mAbs) targeting haemagglutinin (HA) of the H5 2.3.4.4b subclade and their neutralizing abilities. The results indicated that the two mAbs provided specific protection against the H5 2.3.4.4b clade viral challenge in MDCK cells and mouse models. Through epitope identification and docking studies, we showed that these novel sites (which are located near the 130-loop (S136, T143) and 190-helix (N199, N205) of HA receptor-binding sites that contribute to the binding affinity of neutralizing mAbs and six residues of the complementarity-determining regions) can be targeted to generate antibodies with enhanced cross-neutralization. This can also help in understanding escape mutations that differ among the H5 2.3.4.4b, h, and 2.3.2.1c subclades. These results provide specific information to facilitate future vaccine design and therapeutics for both subclade viruses, which are dominant and pose a serious threat to humans.

Highly pathogenic avian influenza (HPAI) has persisted as a One Health threat whose current circulation and impact are addressed in the companion Currents in One Health by Puryear and Runstadler, JAVMA, May 2024. Highly pathogenic avian influenza emerged as a by-product of agricultural practices and adapted to endemic circulation in wild bird species. Over more than 20 years, continued evolution in a complex ecology involving multiple hosts has produced a lineage that expanded globally over the last 2 years. Understanding the continued evolution and movement of HPAI relies on understanding how the virus is infecting different hosts in different contexts. This includes understanding the environmental factors and the natural ecology of viral transmission that impact host exposure and ultimately evolutionary trajectories. Particularly with the rapid host expansion, increased spillover to mammalian hosts, and novel clinical phenotypes in infected hosts, despite progress in understanding the impact of specific mutations to HPAI viruses that are associated with spillover potential, the threat to public health is poorly understood. Active research is focusing on new approaches to understanding the relationship of viral genotype to phenotype and the implementation of research and surveillance pipelines to make sense of the enormous potential for diverse HPAI viruses to emerge from wild reservoirs amid global circulation. [ABSTRACT FROM AUTHOR]

An epidemic of highly pathogenic avian influenza (HPAI) began in North America in the winter of 2021. The introduced Eurasian H5N1 clade 2.3.4.4b virus subsequently reassorted with North American avian influenza strains. This postmortem study describes the lesions and influenza A virus antigen distribution in 3 species of raptors, including bald eagles (Haliaeetus leucocephalus, n = 6), red-tailed hawks (Buteo jamaicensis, n = 9), and great horned owls (Bubo virginianus, n = 8), naturally infected with this virus strain based on positive reverse transcriptase polymerase chain reaction and sequencing results from oropharyngeal swabs. The birds presented with severe neurologic signs and either died or were euthanized because of the severity of their clinical signs and suspected influenza virus infection. Gross lesions were uncommon and included forebrain hemorrhages in 2 eagles, myocarditis in 1 hawk, and multifocal pancreatic necrosis in 3 owls. Histological lesions were common and included encephalitis, myocarditis, multifocal pancreas necrosis, multifocal adrenal necrosis, histiocytic splenitis, and anterior uveitis in decreasing frequency. Influenza A viral antigen was detected in brain, heart, pancreas, adrenal gland, kidney, spleen, liver, and eye. In conclusion, bald eagles, red-tailed hawks, and great horned owls infected with the HPAI clade 2.3.4.4b virus strain and showing neurological signs of illness may develop severe or fatal disease with histologically detectable lesions in the brain that are frequently positive for viral antigen. [ABSTRACT FROM AUTHOR]

Highly pathogenic avian influenza (HPAI) is a viral disease caused by some H5 and H7 subtypes of influenza virus type A in most species of birds, especially poultry. HPAI viruses are among the most challenging viruses that threaten both human and animal health. Consequently, various strategies, such as the use of vaccines have been proposed to control the disease. After a catastrophic pandemic and the failure of conventional methods (elimination and extermination) in Iran, multiple vaccines have been used to control the disease. This study investigates the immunogenicity of two recombinant inactivated commercial vaccines of H5N1 and H5N3 subtypes in laying pullet flocks in Tehran Province, Iran. From 32 halls in six breeding units of laying pullets, 3,200 sera, and 800 tracheal and cloacal swabs were collected. After collecting the samples, Serum neutralisation (SN) and hemagglutination inhibition (HI) tests were conducted on sera to determine the serum titers of H5 specific antibody obtained from vaccine inoculation in three steps: before, after the first vaccination, and after the second vaccination (booster). The SN and HI tests were carried out by the alpha and beta methods on the pooled samples by the vaccine type (as antigen for HI and SN), and the results were compared. The PCR was performed on the tracheal and cloacal swab samples to possibly detect the HA (H5) I virus in the studied flocks. The HI test results showed that both vaccines had a Serum antibody titre above 5 (log2) after two vaccination rounds, indicating a desirable immunogenic response. The SN test results also showed a neutralisation index above 104.5 for both vaccines, indicating more than 50% reduction in antigenicity of the virus. The PCR results were negative. This study was the first investigation of immunogenicity following two-time vaccination against H5 subtype vaccines in Iranian poultry flocks, indicating suitable antibody titer against the influenza virus in vaccinated flocks. [ABSTRACT FROM AUTHOR]

Avian influenza viruses (AIV) remain prevalent among wild bird populations in the European Union and European Economic Area (EU/EEA), leading to significant illness and mortality of birds. Transmission between bird and mammal species has been observed, particularly in fur animal farms, where outbreaks have been reported. While transmission from infected birds to humans is rare, there have been instances of exposure to these viruses since 2020 without any symptomatic infections reported in the EU/EEA. However, these viruses continue to evolve globally, and with the migration of wild birds, new strains carrying potential mutations for mammalian adaptation could be selected. If avian A(H5N1) influenza viruses acquire the ability to spread efficiently among humans, large‐scale transmission could occur due to the lack of immune defences against H5 viruses in humans. The emergence of AIV capable of infecting mammals, including humans, can be facilitated by various drivers. Some intrinsic drivers are related to virus characteristics or host susceptibility. Other drivers are extrinsic and may increase exposure of mammals and humans to AIV thereby stimulating mutation and adaptation to mammals. Extrinsic drivers include the ecology of domestic and wild host species, human activities like farming practices and the use of natural resources, climatic and environmental factors. One Health measures to mitigate the risk of AIV adapting to mammals and humans focus on limiting exposure and preventing spread. Key options for actions include enhancing surveillance targeting humans and animals, ensuring access to rapid diagnostics, promoting collaboration between animal and human sectors, and considering the implementation of preventive measures such as vaccination of poultry. Effective communication to different target audiences should be emphasised, as well as strengthening veterinary infrastructure, enforcing biosecurity measures at farms, and reducing wildlife contact with domestic animals. Careful planning of poultry and fur animal farming, especially in areas with high waterfowl density, is essential for effective risk reduction. [ABSTRACT FROM AUTHOR]

Simple Summary: A concerning highly pathogenic avian influenza caused widespread outbreaks among birds and wildlife at a global level. First identified in South America in October 2022 and linked to migratory birds, there's growing concern about virus spillover during bird migrations between the poles. The Arctic tern's migration from the Arctic to Antarctica raises concerns about its role in transmission. Even in Antarctica's seemingly untouched environment, diverse wildlife is at risk from the new strain of highly pathogenic avian influenza. Surveillance efforts started in the South Shetland Islands in January 2023, focusing on areas where penguins, birds, and marine mammals normally gather. Following Antarctic Treaty guidelines, observations and sample collection were conducted, revealing no signs of the virus in the region during that time lapse. These findings not only contribute to confirming the absence of the virus in Antarctica during the specified period but also emphasize the necessity for sustained surveillance and monitoring to safeguard the Antarctic ecosystem. In January 2023, an active surveillance initiative was undertaken in the South Shetland Islands, Antarctica, with the specific objective of ascertaining evidence for the presence of avian influenza, and specifically the highly pathogenic avian influenza virus subtype H5N1 (HPAIV H5N1). The investigation encompassed diverse locations, including Hanna Point (Livingston Island), Lions Rump (King George Island), and Base Escudero (King George Island), with targeted observations on marine mammals (southern elephant seals), flying birds (the kelp gull, snowy sheathbill and brown skua), and penguins (the chinstrap penguin and gentoo penguin). The study encompassed the examination of these sites for signs of mass mortality events possibly attributable to HPAIV H5N1, as well as sampling for influenza detection by means of real-time RT-PCR. Two hundred and seven (207) samples were collected, including 73 fecal samples obtained from the environment from marine mammals (predominantly feces of southern elephant seals), and 77 cloacal samples from penguins of the genus Pygoscelis (predominantly from the gentoo penguin). No evidence of mass mortality attributable to HPAIV H5N1 was observed, and all the collected samples tested negative for the presence of the virus, strongly suggesting the absence of the virus in the Antarctic territory during the specified period. This empirical evidence holds significant implications for both the ecological integrity of the region and the potential zoonotic threats, underscoring the importance of continued surveillance and monitoring in the Antarctic ecosystem. [ABSTRACT FROM AUTHOR]

Avian influenza (AI) is a highly contagious viral disease that constitutes a significant threat to birds worldwide. Particularly concerning are highly pathogenic AI (HPAI) viruses of the H5 subtype, which have caused extensive losses in both poultry and wild bird flocks. For this reason, the European Union (EU) mandated Member States (MSs) to carry out surveillance for AI in both poultry and wild birds. Passive surveillance, which aims at the virological detection of AI in wild birds found dead or moribund, is part of this surveillance programme. To aid the MSs, a list of wild bird target species for the passive surveillance of H5 HPAI viruses in Europe was first published by the European Food Safety Authority (EFSA) in 2017. This report presents an update of that list. To compile this updated list, both epidemiological and ornithological data were used. Epidemiological data consisted of passive surveillance data submitted by the MSs to EFSA. Ornithological data was derived from literature and expert knowledge. Species were given scores for traits relevant for spreading HPAI among wild birds, such as habitat type and degree of gregariousness. Species were then categorised into ecological groups, based on their relevance for early warning purposes, considering the likelihood of virus transmission to poultry. Within these groups, the ranking of the species was determined by their scores for both HPAI history and ecological traits. The final updated target list comprises 241 bird species, which are all to be considered risk species and can be targeted in passive surveillance programmes. Depending on individual needs and available budget, this report provides suggestions on which ecological groups to focus on and which events to prioritise. This list aims at helping MSs in prioritising passive surveillance sampling efforts, thus increasing insights into the spread of HPAI in wild birds in Europe. [ABSTRACT FROM AUTHOR]

This study describes clinical manifestations of highly pathogenic avian influenza (HPAI) H5N1, H5N8 and H5N6 outbreaks between 2014 and 2018 and 2020 and 2022 in the Netherlands for different poultry types and age groups. Adult duck (breeder) farms and juvenile chicken (broiler and laying pullet) farms were not diagnosed before 2020. Outbreaks in ducks decreased in 2020–2022 vs. 2014–2018, but increased for meat-type poultry. Neurological, locomotor and reproductive tract signs were often observed in ducks, whereas laying- and meat-type poultry more often showed mucosal membrane and skin signs, including cyanosis and hemorrhagic conjunctiva. Juveniles (chickens and ducks) showed neurological and locomotor signs more often than adults. Diarrhea occurred more often in adult chickens and juvenile ducks. Mortality increased exponentially within four days before notification in chickens and ducks, with a more fluctuating trend in ducks and meat-type poultry than in layers. For ducks, a mortality ratio (MR) > 3, compared to the average mortality of the previous week, was reached less often than in chickens. A lower percentage of laying flocks with MR > 3 was found for 2020–2022 vs. 2014–2018, but without significant differences in clinical signs. This study provides a basis for improvements in mortality- and clinical-sign-based early warning criteria, especially for juvenile chickens and ducks. [ABSTRACT FROM AUTHOR]

We reviewed information about mammals naturally infected by highly pathogenic avian influenza A virus subtype H5N1 during 2 periods: the current panzootic (2020–2023) and previous waves of infection (2003–2019). In the current panzootic, 26 countries have reported >48 mammal species infected by H5N1 virus; in some cases, the virus has affected thousands of individual animals. The geographic area and the number of species affected by the current event are considerably larger than in previous waves of infection. The most plausible source of mammal infection in both periods appears to be close contact with infected birds, including their ingestion. Some studies, especially in the current panzootic, suggest that mammal-to-mammal transmission might be responsible for some infections; some mutations found could help this avian pathogen replicate in mammals. H5N1 virus may be changing and adapting to infect mammals. Continuous surveillance is essential to mitigate the risk for a global pandemic.

The review provides brief historical information on the highly pathogenic influenza A (H5) and presents data on massive outbreaks caused by this subtype. It includes historical background, data on outbreaks, and the formation of potentially pandemic viruses. The abstract also highlights the current state of the problem, such as the spread of H5 influenza in new territories and its ability to infect mammals and humans. The issues of vaccination for poultry and the challenges of implementing it globally are addressed. Furthermore, the risks of further spread of the virus and the emergence of pandemic strains are being discussed.

The global spread of highly pathogenic avian influenza (HPAI) A (H5N1) clade 2.3.4.4b virus since 2021 necessitates a re-evaluation of the role of vaccination in controlling HPAI outbreaks among poultry, which has been controversial because of the concern of silent spread with viral mutation and spillover to human. We systematically reviewed and meta-analyzed all existing data from experimental challenge trials to assess the efficacy of HPAI vaccines against mortality in specific pathogen free (SPF) chickens, with evaluation of the certainty of evidence (CoE) using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. Out of 223 screened publications, 46 trials met our eligibility criteria. Inactivated vaccines showed an efficacy of 95% (risk ratio [RR] = 5% [95% CI: 1% to 17%], I2 = 0%, CoE high) against homologous strains and an efficacy of 78% (RR = 22% [95% CI: 14% to 37%], I2 = 18%, CoE high) against heterologous strains (test for subgroup difference p = 0.02). Live recombinant vaccines exhibited the highest efficacy at 97% (RR = 3% [95% CI: 1% to 13%], I2 = 0%, CoE high). Inactivated recombinant vaccines had an overall efficacy of 90% (RR = 10% [95% CI: 6% to 16%], I2 = 47%, CoE high). Commercial vaccines showed an overall efficacy of 91% (RR = 9% [95% CI: 5% to 17%], I2 = 23%, CoE high), with 96% efficacy (RR = 4% [95% CI: 1% to 21%], I2 = 0%, CoE high) against homologous strains and 90% efficacy (RR = 10% [95% CI: 5% to 20%], I2 = 31%, CoE moderate) against heterologous strains. Our systematic review offers an updated and unbiased assessment of vaccine efficacy against HPAI-related mortality, providing timely and crucial information for re-evaluating the role of vaccination in poultry avian influenza control policy amist the global HPAI outbreak post-2021.

Abstract Avian influenza viruses (AIV) remain prevalent among wild bird populations in the European Union and European Economic Area (EU/EEA), leading to significant illness and mortality of birds. Transmission between bird and mammal species has been observed, particularly in fur animal farms, where outbreaks have been reported. While transmission from infected birds to humans is rare, there have been instances of exposure to these viruses since 2020 without any symptomatic infections reported in the EU/EEA. However, these viruses continue to evolve globally, and with the migration of wild birds, new strains carrying potential mutations for mammalian adaptation could be selected. If avian A(H5N1) influenza viruses acquire the ability to spread efficiently among humans, large‐scale transmission could occur due to the lack of immune defences against H5 viruses in humans. The emergence of AIV capable of infecting mammals, including humans, can be facilitated by various drivers. Some intrinsic drivers are related to virus characteristics or host susceptibility. Other drivers are extrinsic and may increase exposure of mammals and humans to AIV thereby stimulating mutation and adaptation to mammals. Extrinsic drivers include the ecology of domestic and wild host species, human activities like farming practices and the use of natural resources, climatic and environmental factors. One Health measures to mitigate the risk of AIV adapting to mammals and humans focus on limiting exposure and preventing spread. Key options for actions include enhancing surveillance targeting humans and animals, ensuring access to rapid diagnostics, promoting collaboration between animal and human sectors, and considering the implementation of preventive measures such as vaccination of poultry. Effective communication to different target audiences should be emphasised, as well as strengthening veterinary infrastructure, enforcing biosecurity measures at farms, and reducing wildlife contact with domestic animals. Careful planning of poultry and fur animal farming, especially in areas with high waterfowl density, is essential for effective risk reduction.

ABSTRACT: This symposium offered up-to-date perspectives on field experiences and the latest research on significant viral and bacterial diseases affecting poultry. A highlight was the discussion on the use of enteroids as advanced in vitro models for exploring disease pathogenesis. Outcomes of this symposium included identifying the urgent need to improve the prevention and control of avian influenza by focusing research on vaccine effectiveness. In this regard, efforts should focus on enhancing the relatedness of vaccine antigen to the field (challenge) virus strain and improving immunogenicity. It was also revealed that gangrenous dermatitis could be controlled through withholding or restricting the administration of ionophores during broiler life cycle, and that administration of microscopic polymer beads (gel) based-live coccidia vaccines to chicks could be used to reduce necrotic enteritis-induced mortality. It was emphasized that effective diagnosis of re-emerging Turkey diseases (such as blackhead, fowl cholera, and coccidiosis) and emerging Turkey diseases such as reoviral hepatitis, reoviral arthritis, Ornithobacterium rhinotracheale infection, and strepticemia require complementarity between investigative research approaches and production Veterinarian field approaches. Lastly, it was determined that the development of a variety of functionally-specific enteroids would expedite the delineation of enteric pathogen mechanisms and the identification of novel vaccine adjuvants.

In May 2022, we observed a substantial die-off of wild migratory waterbirds on Maliy Zhemchuzhniy Island in the Caspian Sea, Russia. The deaths were caused by highly pathogenic avian influenza A(H5N1) clade 2.3.4.4.b virus. Continued surveillance of influenza viruses in wild bird populations is needed to predict virus spread over long distances.

Highly pathogenic avian influenza (HPAI) is a highly contagious viral disease that represents a significant threat to poultry production worldwide. Variants of the HPAI virus (HPAIV) H5A/Goose/GuangDong/1/96 (H5 Gs/GD/96) lineage have caused five intercontinental epizootic waves, with the most recent, clade 2.3.4.4b, reaching Argentina in February 2023. Initially detected in wild birds, the virus quickly spread to backyard and commercial poultry farms, leading to economic losses, including the loss of influenza-free status (IFS). By March/April 2023 the epidemic had peaked and vaccination was seriously considered. However, the success of strict stamping-out measures dissuaded the National Animal Health Authority (SENASA) from authorizing any vaccine. Suspected cases sharply declined by May, and the last detection in commercial poultry was reported in June. The effective control and potential eradication of HPAIV in Argentina were due to SENASA’s early detection and rapid response, supported by private companies, veterinarians, and other stakeholders. Stamping-out measures have been effective for virus elimination and reduced farm-to-farm transmission; however, as the virus of this clade may remain present in wild birds, the risk of reintroduction into poultry production is high. Therefore, maintaining continuous active surveillance will be crucial for promptly detecting any new HPAIV incursion and taking appropriate action to contain virus dissemination.

Since early 2024, a multistate outbreak of highly pathogenic avian influenza H5N1 has been affecting dairy cattle in the USA. The influenza viral RNA concentrations in milk make it an ideal matrix for surveillance purposes. However, viral RNA detection in multi-component fluids such as milk can be complex, and optimization of influenza detection methods is thus required. Raw bulk tank milk and mastitis milk samples were artificially contaminated with an avian influenza strain and subjected to five extraction methods. HCoV-229E and synthetic RNA were included as exogenous internal process controls. Given the high viral load usually observed in individual raw milk samples, four out of five tested methods would enable influenza detection in milk with normal texture, over a time window of at least 2 weeks post-onset of clinical signs. Nevertheless, sample dilution 1:3 in molecular transport medium prior to RNA extraction provided the best results for dilution of inhibitory substances and a good recovery rate of influenza RNA, that reached 12.5 ± 1.2% and 10.4 ± 3.8% in two independent experiments in bulk milk and 11.2 ± 3.6% and 10.0 ± 2.9% on two cohorts of mastitis milk samples. We have also shown compatibility of an influenza RT-qPCR system with synthetic RNA detection for simultaneous validation of the RNA extraction and RT-qPCR processes.

The highly pathogenic avian influenza (HPAI) virus triggers infectious diseases, resulting in pulmonary damage and high mortality in domestic poultry worldwide. This study aimed to analyze miRNA expression profiles after infection with the HPAI H5N1 virus in resistant and susceptible lines of Ri chickens.For this purpose, resistant and susceptible lines of Vietnamese Ri chicken were used based on the A/G allele of Mx and BF2 genes. These genes are responsible for innate antiviral activity and were selected to determine differentially expressed (DE) miRNAs in HPAI-infected chicken lines using small RNA sequencing. A total of 44 miRNAs were DE after 3 days of infection with the H5N1 virus. Computational program analysis indicated the candidate target genes for DE miRNAs to possess significant functions related to cytokines, chemokines, MAPK signaling pathway, ErBb signaling pathway, and Wnt signaling pathway. Several DE miRNA-mRNA matches were suggested to play crucial roles in mediating immune functions against viral evasion. These results revealed the potential regulatory roles of miRNAs in the immune response of the two Ri chicken lines against HPAI H5N1 virus infection in the lungs.

ABSTRACT: In China, fresh food has always been a top priority and live poultry has been a staple in the diet for thousands of years. As a result, the live poultry market (LPM) remains a popular and important source for purchasing live poultry among the public. However, LPMs also play a crucial role in spreading and retaining highly pathogenic avian influenza (HPAI) due to the high poultry movement and trade volume. Therefore, the preventive behavior of LPM vendors is essential in blocking the transmission of HPAI and reducing occupational exposure. Based on the health belief model, this study utilized structural equation modeling to examine the effect of risk perceptions on preventive behavior among vendors in the live poultry wholesale market (wLPM) and the live poultry retail market (rLPM) in Guangdong Province. The results indicated that perceived severity and perceived benefits positively influenced the wLPM vendors’ ability to adopt preventive behavior (i.e., self-efficacy) while perceived barriers negatively affected self-efficacy in both wLPM and rLPM. Moreover, cues to action positively mediated the relationship between perceived severity, perceived benefits, and self-efficacy of wLPM and rLPM vendors. Cues to action also positively mediated the effect of perceived susceptibility among wLPM vendors. To promote preventive behavior among vendors, the market management companies and the government must provide timely and effective HPAI information through various channels and develop differentiated health campaigns according to the market types to raise vendors’ awareness about HPAI.

Background: Highly pathogenic avian influenza (HPAI) has caused substantial economic losses worldwide. An understanding of the environmental drivers that contribute to spillover transmission from wild birds to poultry farms is important for predicting areas at risk of introduction and developing risk-based surveillance strategies. We conducted an epidemiological study using data from six HPAI outbreak events in South Korea. Materials and methods: An aggregate-level study design was implemented using third-level administrative units in South Korea. Only regions with high natural reservoir suitability were included. The incidence of HPAI at chicken and duck farms during the initial phase (30 and 45 days after the first case) of each outbreak event was used as the outcome variable, assuming that cross-species transmission from wild birds was the dominant exposure leading to infection. Candidate environmental drivers were meteorological factors, including temperature, precipitation, humidity, and altitude, as well as the proportion of protected area, farm density, deforestation level, and predator species richness. Logistic regression models were implemented; conditional autoregression models were used in cases of spatial autocorrelation of residuals. Results: Lower temperature, higher farm density, and lower predator species richness were significantly associated with a higher risk of HPAI infection on chicken farms. Lower temperature, higher proportion of protected area, and lower predator species richness were significantly associated with a higher risk of HPAI infection on duck farms. Conclusion: The predicted dominant transmission routes on chicken and duck farms were horizontal and spillover, respectively. These results reveal a potential protective effect of predator species richness against HPAI outbreaks. Further studies are required to confirm a causal relationship. [ABSTRACT FROM AUTHOR]

Introduction: The 2022-2023 highly pathogenic avian influenza (HPAI) H5N1 outbreak in the United States (U.S.) is the largest and most costly animal health event in U.S. history. Approximately 70% of commercial farms affected during this outbreak have been turkey farms. Methods: We conducted a case-control study to identify potential risk factors for introduction of HPAI virus onto commercial meat turkey operations. Data were collected from 66 case farms and 59 control farms in 12 states. Univariate and multivariable analyses were conducted to compare management and biosecurity factors on case and control farms. Results: Factors associated with increased risk of infection included being in an existing control zone, having both brooders and growers, having toms, seeing wild waterfowl or shorebirds in the closest field, and using rendering for dead bird disposal. Protective factors included having a restroom facility, including portable, available to crews that visit the farm and workers having access and using a shower at least some of the time when entering a specified barn. Discussion: Study results provide a better understanding of risk factors for HPAI infection and can be used to inform prevention and control measures for HPAI on U.S. turkey farms. [ABSTRACT FROM AUTHOR]

The continuous evolution of H5Nx highly pathogenic avian influenza viruses (HPAIVs) is a major concern for accurate diagnosis. We encountered some challenges in subtyping and sequencing a recently isolated H5N1 HPAIV strain using classical diagnostic methods. Oropharyngeal, conjunctival, and cloacal swabs collected from a dead white-tailed eagle (Haliaeetus albicilla albicilla) were screened via real-time RT-PCR targeting the influenza A virus matrix (M) gene, followed by virus isolation. The hemagglutination inhibition test was applied in order to subtype and antigenically characterize the isolate using anti-A/duck/Hong Kong/820/80 (H5N3) reference serum or anti-H5N1 cross-clade monoclonal antibodies (mAbs). Sequencing using previously reported universal primers was attempted in order to analyze the full-length hemagglutinin (HA) gene. Oropharyngeal and conjunctival samples were positive for the M gene, and high hemagglutination titers were detected in inoculated eggs. However, its hemagglutination activity was not inhibited by the reference serum or mAbs. The antiserum to a recently isolated H5N1 clade 2.3.4.4b strain inhibited our isolate but not older strains. A homologous sequence in the previously reported forward primer and HA2 region in our isolate led to partial HA gene amplification. Finally, next-generation sequencing confirmed the isolate as H5N1 clade 2.3.4.4b HPAIV, with genetic similarity to H5N1 strains circulating in Japan since November 2021. [ABSTRACT FROM AUTHOR]

During February 7─September 3, 2022, a total of 39 US states experienced outbreaks of highly pathogenic avian influenza A(H5N1) virus in birds from commercial poultry farms and backyard flocks. Among persons exposed to infected birds, highly pathogenic avian influenza A(H5) viral RNA was detected in 1 respiratory specimen from 1 person.

Simple Summary: The basilar artery is a vital cerebral blood vessel common in most vertebrates and constantly supplies blood to the hindbrain where many vital functions are coordinated. Avian basilar arterial responsiveness to vasoactive substances has been characterized only in chickens. In this artery, the endothelium plays an important role in relaxation, and endothelial dependence may explain the lethality of the highly pathogenic avian influenza virus, which reportedly induces apoptosis in the cerebrovascular endothelium. Our present results in ducks suggest a contrast to the previously reported results in chickens with regard to basilar arterial relaxation: The involvement of endothelial nitric oxide as a relaxing factor appears to be reduced in duck basilar arteries. Our research may help scientists to better understand the resistance to the highly pathogenic avian influenza virus that may be conferred by the cerebrovascular endothelium in ducks. The basilar arterial endothelium mediates blood vessel relaxation partly through the release of nitric oxide (NO). Apoptosis of cerebrovascular endothelial cells is linked to a high mortality rate in chickens infected with the highly pathogenic avian influenza virus, but interestingly, ducks exhibit a greater resistance to this virus. In this study, we examined the responsiveness of duck basilar arteries (BAs) to various vasoactive substances, including 5-hydroxytryptamine (5-HT), histamine (His), angiotensin (Ang) II, noradrenaline (NA), acetylcholine (ACh), and avian bradykinin ornithokinin (OK), aiming to characterize the receptor subtypes involved and the role of endothelial NO in vitro. Our findings suggest that arterial contraction is mediated with 5-HT1 and H1 receptors, while relaxation is induced with β3-adrenergic and M3 receptors. Additionally, OK elicited a biphasic response in duck BAs, and Ang II had no effect. Endothelial NO appears to be crucial in relaxation mediated with M3 and OK receptors but not β3-adrenergic receptors in the duck BA. The reduced endothelial NO involvement in the receptor-mediated relaxation response in duck BAs represents a clear difference from the corresponding response reported in chicken BAs. This physiological difference may explain the differences in lethality between ducks and chickens when vascular endothelial cells are infected with the virus. [ABSTRACT FROM AUTHOR]

Controlling avian influenza viruses (AIVs) is mainly based on culling of the infected bird flocks or via the implementation of inactivated vaccines in countries where AIVs are considered to be endemic. Over the last decade, several avian influenza virus subtypes, including highly pathogenic avian influenza (HPAI) H5N1 clade 2.2.1.2, H5N8 clade 2.3.4.4b and the recent H5N1 clade 2.3.4.4b, have been reported among poultry populations in Egypt. This demanded the utilization of a nationwide routine vaccination program in the poultry sector. Antigenic differences between available avian influenza vaccines and the currently circulating H5Nx strains were reported, calling for an updated vaccine for homogenous strains. In this study, three H5Nx vaccines were generated by utilizing the reverse genetic system: rgH5N1_2.3.4.4, rgH5N8_2.3.4.4 and rgH5N1_2.2.1.2. Further, the immunogenicity and the cross-reactivity of the generated inactivated vaccines were assessed in the chicken model against a panel of homologous and heterologous H5Nx HPAIVs. Interestingly, the rgH5N1_2.3.4.4 induced high immunogenicity in specific-pathogen-free (SPF) chicken and could efficiently protect immunized chickens against challenge infection with HPAIV H5N1_2.3.4.4, H5N8_2.3.4.4 and H5N1_2.2.1.2. In parallel, the rgH5N1_2.2.1.2 could partially protect SPF chickens against infection with HPAIV H5N1_2.3.4.4 and H5N8_2.3.4.4. Conversely, the raised antibodies to rgH5N1_2.3.4.4 could provide full protection against HPAIV H5N1_2.3.4.4 and HPAIV H5N8_2.3.4.4, and partial protection (60%) against HPAIV H5N1_2.2.1.2. Compared to rgH5N8_2.3.4.4 and rgH5N1_2.2.1.2 vaccines, chickens vaccinated with rgH5N1_2.3.4.4 showed lower viral shedding following challenge infection with the predefined HPAIVs. These data emphasize the superior immunogenicity and cross-protective efficacy of the rgH5N1_2.3.4.4 in comparison to rgH5N8_2.3.4.4 and rgH5N1_2.2.1.2. [ABSTRACT FROM AUTHOR]

Since the first 2006 Avian Influenza (AI) outbreak in Nigeria, it has continued to circulate and ravage the poultry industry with huge economic losses above 130 billion naira. Local poultry are important sources of AI transmission and maintenance of the highly pathogenic avian influenza H5N1. Live bird markets (LBMs) are "breeding grounds" and major risk factors for human infection of AI. The seroprevalence of AI in local chickens in LBMs in Kaduna Metropolis, Nigeria was determined. Sera were obtained from the local chickens (n=300) in 5 daily LBMs and subjected to competitive enzyme-linked immunosorbent assay (c-ELISA) to detect the nucleoprotein antibodies. The c-ELISA positive samples were further screened by haemagglutination inhibition (HI) test for AI using H5, H7 and H9 antigens. The overall AI seroprevalence was 1.7 % with the highest individual seroprevalence of 3.3% in Kawo and Railway LBMs. There was no statistically significant association between the location of LBMs and AI presence, and between the sex and presence of AI antibodies (p = 0.427). One sample was HI positive for antibodies against H5, H7 and H9 with mean titers of 4, 2.5 and 3.5 log2, respectively. This implies the potential danger of the spread of AI among humans and animals. There should be sustained surveillance and biosecurity in the live bird market. [ABSTRACT FROM AUTHOR]

Copyright of Épidémiologie et Santé Animale is the property of Association pour l'Etude de l'Epidemiologie des Maladies Animales (AEEMA) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Highly pathogenic avian influenza viruses (HPAIVs) of hemagglutinin type H5 and clade 2.3.4.4b have widely spread within the northern hemisphere since 2020 and threaten wild bird populations, as well as poultry production. We present phylogeographic evidence that Iceland has been used as a stepping stone for HPAIV translocation from northern Europe to North America by infected but mobile wild birds. At least 2 independent incursions of HPAIV H5N1 clade 2.3.4.4b assigned to 2 hemagglutinin clusters, B1 and B2, are documented for summer‒autumn 2021 and spring 2022. Spread of HPAIV H5N1 to and among colony-breeding pelagic avian species in Iceland is ongoing. Potentially devastating effects (i.e., local losses >25%) on these species caused by extended HPAIV circulation in space and time are being observed at several affected breeding sites throughout the North Atlantic.

In August 2021, we detected highly pathogenic avian influenza A(H5N1) clade 2.3.4.4b viruses in poultry in southern Benin. The isolates were genetically similar to H5N1 viruses of clade 2.3.4.4b isolated during the same period in Africa and Europe. We also found evidence for 2 separate introductions of these viruses into Benin.

High pathogenicity avian influenza (HPAI) viruses of clade 2.3.4.4 H5Nx have been circulating in poultry and wild birds worldwide since 2014. In South Korea, after the first clade 2.3.4.4b H5N1 HPAI viruses were isolated from wild birds in October 2021, additional HPAIV outbreaks occurred in poultry farms until April 2022. In this study, we genetically characterized clade 2.3.4.4b H5N1 HPAIV isolates in 2021–2022 and examined the pathogenicity and transmissibility of A/mandarin duck/Korea/WA585/2021 (H5N1) (WA585/21) in chickens and ducks. Clade 2.3.4.4b H5N1 HPAI viruses caused 47 outbreaks in poultry farms and were also detected in multiple wild birds. Phylogenetic analysis of HA and NA genes indicated that Korean H5N1 HPAI isolates were closely related to Eurasian viruses isolated in 2021–2022. Four distinct genotypes of H5N1 HPAI viruses were identified in poultry, and the majority were also found in wild birds. WA585/21 inoculated chickens showed virulent pathogenicity with high mortality and transmission. Meanwhile, ducks infected with the virus showed no mortality but exhibited high rates of transmission and longer viral shedding than chickens, suggesting that they may play an important role as silent carriers. In conclusion, consideration of both genetic and pathogenic traits of H5N1 HPAI viruses is required for effective viral control. [ABSTRACT FROM AUTHOR]