Patterns of Avian Influenza Virus detection from active surveillance in wild birds: A systematic review and meta-analysis.

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ABSTRACTActive surveillance of avian influenza virus (AIV) in wetlands and lakes is important for exploring the gene pool in wild birds. Through active surveillance from 2015 through 2019, 10,900 samples from wild birds in central China were collected, and 89 AIVs were isolated, including 2 subtypes of highly pathogenic AIV and 12 of low-pathogenic AIV; H9N2 and H6Ny were the dominant subtypes. Phylogenetic analysis of the isolates demonstrated that extensive intersubtype reassortments and frequent intercontinental gene exchange occurred in AIVs. AIV gene segments persistently circulated in several migration seasons, but interseasonal persistence of the whole genome was rare. The whole genomes of one H6N6 and polymerase basic 2 (PB2), polymerase acidic (PA), hemagglutinin (HA), neuraminidase (NA), M, and nonstructural (NS) genes of one H9N2 virus were found to be of poultry origin, suggesting a spillover of AIVs from poultry to wild birds. Importantly, one H9N2 virus only bound to human-type receptor, and one H1N1, four H6, and seven H9N2 viruses possessed dual receptor-binding capacity. Nineteen of 20 representative viruses tested could replicate in the lungs of mice without preadaptation, which poses a clear threat of infection in humans. Together, our study highlights the need for intensive AIV surveillance.IMPORTANCE Influenza virus surveillance in wild birds plays an important role in the early recognition and control of the virus. However, the AIV gene pool in wild birds in central China along the East Asian-Australasian flyway has not been well studied. Here, we conducted a 5-year AIV active surveillance in this region. Our data revealed the long-term circulation and prevalence of AIVs in wild birds in central China, and we observed that intercontinental gene exchange of AIVs is more frequent and continuous than previously thought. Spillover events from poultry to wild bird were observed in H6 and H9 viruses. In addition, in 20 representative viruses, 12 viruses could bind human-type receptors, and 19 viruses could replicate in mice without preadaption. Our work highlights the potential threat of wild bird AIVs to public health.

1. Modes of transmission and the origin of H5N1 virusesAvian Influenza (A.I.) is transmitted by infected birds and their excrements. Also, AI is mechanically transmitted by surface means via contaminated food, water, feeds, soil, vehicles, humans, animals, flies, feathers etc. AI viruses can be spread by national or international trades of infected birds and contaminated products. Wild birds, especially migratory waterfowl, are a recognized source and reservoir for all subtypes of AI viruses. Some mammals such as dogs and cats are susceptible to the virus, but they are usually considered as the dead ends.In 1996, H5N1 virus was first detected in Guangdong Province, China. In 1997 the virus became widespread in poultry markets in Hong Kong, and killed 6 of 18 infected persons. The virus was wiped out by culling all domestic poultry in Hong Kong. In 2002, a new H5N1 genotype appeared again in Hong Kong, and the variant strains spread across Southeast Asia and South Asia between 2002 and 2007. The viruses can be divided into several clades such as V1, V2, V3 and Indonesian clades. The strains of H5N1 virus appeared in Korea (2003) and Japan (2004) were closely related to Guangdong strain/174/04 which is distinct from the abov 4 clades.In April 2005, a new variant H5N1 virus, which caused high mortality in both wild birds and poultry, was observed in Quinghai Lake, China. The virus was spread westward through migratory birds into Siberia, Kazakhstan and Turkey. This unprecedented mortality of wild birds associated with H5N1 viruses opened a new window for its movement within wild and domestic birds across Eurasia, the Near East and Africa. Virus strains are divided into 3 clades (EMA 1, 2, 3). The virus isolated in 2007 in Japan is closely related to one of those viruses of Quinghai origin (EMA clades).2. AI situation in EuropeThe European Union decided to make risk assessments of H5N1 virus entering via migratory birds into Europe, and active and passive surveillance for AI virus in wild birds started in July 2005. The conclusion of this study indicated a high risk of introducing the virus via migratory birds, and also a risk of the infection to become enzootic in Europe.The EU encouraged each member country (a) to make an extensive survey of AI viruses in both wild and domestic birds, (b) to vaccinate zoo birds and poultry that cannot be kept in houses (c) to keep all domestic birds in closed housing in high risk areas or zones and (d) to vaccinate domestic birds that cannot be housed.Between 2005 and 2006, H5N1 viruses were detected in wild birds in 25 countries. AI outbreaks in poultry farms were reported from 13 countries in Eastern Europe, and 4 countries in Western Europe (Sweden, Denmark, France and Germany). It is considered that migratory birds played a major role in spreading H5N1 viruses in Europe.The results of the risk control measures in Western Europe can be summarized as follows : (i) It was successful to protect the zoo birds by vaccination, but several birds died due to trauma of vaccination.(ii) Surveillance of wild birds was useful in improving early warning systems for poultry producers, and was effective in reducing the exposure risks of poultry.(iii) Mass culling of poultry and ornamental birds could be avoided.In 2007, H5N1 virus surfaced again in Hungary, UK, Czech R., Germany and France. It seems that H5N1 viruses became enzootic in some countries in Eastern Europe including Russia.(View PDF for the rest of the abstract.)

H11 subtype avian influenza viruses (AIVs) have been identified in both wild and domestic birds. H11N9 viruses from wild birds provided the NA gene to human H7N9 virus in 2013 in China, which caused five waves of human infections. During active surveillance in wild birds in China, 17 H11 viruses were isolated between December 2022 and January 2024, including six H11N1, one H11N2, one H11N3, and nine H11N9. The epidemiology of H11 subtype viruses in public databases revealed that they distributed across seven continents, and more than 54.9% of H11 viruses originated from wild Anseriformes. Phylogenetic analysis of the HA genes indicated that H11 viruses were classified into Eurasian and North American lineages, and our isolates belonged to the Eurasian lineage. Bayesian phylogeographic analysis suggested that Bangladesh served as a crucial geographical transmission center for H11 viruses in Eurasian lineage. Reassortment indicated that the H11 isolates in the study underwent complex genomic recombination with various subtype AIVs circulating in wild and domestic birds, including the clade 2.3.4.4b H5N1 highly pathogenic viruses, and formed seven genotypes. Notably, 17 H11 isolates acquired several mutations associated with enhanced human-type receptor binding in HA (S137A) and increased mammalian virulence in PB1 (D3V, D622G), PB1-F2 (N66S), M1 (N30D, I43M, T215A), and NS1 (P42S, I106M). Seven representative viruses exhibited dual receptor binding specificity and could infect mice directly without prior adaptation. These findings highlight the potential public health risks posed by H11 viruses from wild birds and emphasize the necessity of enhancing routine surveillance.

Surveillance in wild birds is essential for the timely detection of high pathogenicity avian influenza (HPAI) strains. As flocks congregate in large numbers in wetlands and may potentially contaminate the environment with pathogens, the monitoring of such water bodies represents an attractive opportunity to complement animal testing and to improve surveillance for avian influenza. To increase sensitivity, water concentration is often required but available methods based on (ultra)filtration and precipitation are mostly limited by the use of pumping equipment and by the need to identify the representative sample volumes. In contrast, passive samplers (PS) offer a cost-effective and scalable solution that requires basic devices for the deployment of adsorbent materials and minimal training for their installation in the field. This study evaluated nine materials for their virus adsorption efficiency in brackish and freshwater. Cotton gauze, nitrocellulose, and nylon showed the best performance across different deployment times, with the highest recovery after 24 h. Shorter (3 h) and longer (7 days) deployments also proved effective, accommodating different sampling regimens according to the logistical needs. Importantly, PS revealed their efficacy in adsorbing also deteriorated virions or in dynamic ecosystems subjected to changes in water volumes. Field trials in wetlands corroborated laboratory findings and demonstrated that PS allowed detecting avian influenza virus (AIV, including HPAI strains) genome in water bodies, yielding consistent results with active surveillance in wild birds. By offering a simple, cost-effective, and versatile solution, PS represent a promising tool for environmental AI monitoring and can successfully complement existing avian influenza surveillance activities.

Event Abstract Back to Event Identification of highly pathogenic avian influenza suitable areas for wild birds using species distribution models in South Korea. Lee Kyuyoung1*, Dae-sung Yu2*, Beatriz Martínez-López1, Jaber A. Belkhiria1, Sung-il Kang2, Hachung Yoon2, Seong-Keun Hong2, ILSEOB LEE2, Han-Mo Son2 and Kwangnyeong Lee2 1 Department of Medicine & Epidemiology, School of Veterinary Medicine, University of California, Davis, United States 2 Animal and Plant Quarantine Agency (South Korea), Republic of Korea Highly pathogenic avian influenza (HPAI) virus is influenza A type virus with high mortality and morbidity in the broad range of host species domestic and wild birds to humans. HPAI infection has been a high-priority concern in global poultry industry because of consistent generation and circulation of novel HPAI strains, and consequent tremendous financial losses. Wild birds are considered one of the most important sources of novel HPAI introductions in poultry farms due to the experimental evidence of their asymptomatic infection with viral shedding, genetic closeness of HPAI virus identified in domestic poultry and wild birds, and spatial and temporal coincidence of identification of HPAI in wild birds and domestic poultry. The poultry industry in South Korea has annually suffered from the introduction of novel HPAI strains since early 2000s. HPAI infection in annually migrated wild birds has been carefully monitored to rapidly establish preventive measures of HPAI introduction into poultry farms in South Korea. However, current understanding of highly risk areas or suitable areas for HPAI in wild birds and contribution of other geographical and environmental factors contributing to HPAI vírus suitability is limited. Application of species distribution models based on digitalized geographical and environmental information facilitates our understanding about suitability of wild species’ habitat and its association with environmental and geographical factors. Furthermore, species distribution modelling can be applied to identify high-risk areas of potential disease transmission at the interface between wild species and domestic animals. Our study aimed to evaluate the areas with higher suitability/risk for HPAI identification in wild birds in South Korea and to describe what is the influence or association with the different environmental and geographical factors. Our results will help to not only have a better understanding of the ecology of HPAI in wild birds but also to establish more effective, risk-based, surveillance to prevent novel HPAI introductions into domestic poultry farms in South Korea We obtained land cover, monthly climate (precipitation, temperature and wind speed) and ecological preservation area (Level 1-3) data of South Korea in digitalized form as environmental and geographical data. The observation records of 7 species of wild birds (Baikal teal, white-front goose, common teal, mandarin duck, mallard, bean goose, spot-billed duck) in 206 habitats in South Korea from 1999 to 2017 were used to estimate the suitability map for the wild bird distribution in South Korea. The geographical records of wild bird HPAI surveillance from 2014 to 2018 was combined with 7 wild birds species distribution and environmental and geographical data to estimate the suitability map of HPAI identification in wild birds. Each suitability maps was estimated by maximum entropy approach (Maxent model) via the “dismo” package in R studio. 3. Results and Discussion Our study presents the suitability map of HPAI identification in wild birds and how geographical, environmental factors and 7 wild birds species distributions are contributing to the prediction. These results will not only provide a high-resolution map for the target allocation of surveillance and rapid detection of HPAI in wild birds but also will allow the improvement of the cost-effectiveness of risk-based surveillance of HPAI introduction into domestic poultry farms in South Korea. Acknowledgements This study was supported by the 2019-20 cooperative research grant from the veterinary epidemiology Division in the Animal and Plant Quarantine Agency (APQA) in South Korea and the fellowship of the graduate student support program (GSSP) at UC Davis

No human infections due to highly pathogenic avian influenza (HPAI) A(H5N8) or A(H5N6) viruses ‐ detected in wild birds and poultry outbreaks in Europe ‐ have been reported so far and the risk of zoonotic transmission to the general public in Europe is considered very low. Between 16 November 2018 and 15 February 2019, two HPAI A(H5N8) outbreaks in poultry establishments in Bulgaria, two HPAI A(H5N6) outbreaks in wild birds in Denmark and one low pathogenic avian influenza (LPAI) A(H5N3) in captive birds in the Netherlands were reported in the European Union (EU). Genetic characterisation of the HPAI A(H5N6) viruses reveals that they cluster with the A(H5N6) viruses that have been circulating in Europe since December 2017. The wild bird species involved were birds of prey and were likely infected due to hunting or scavenging infected wild waterfowl. However, HPAI virus was not detected in other wild birds during this period. Outside the EU, two HPAI outbreaks were reported in poultry during the reporting period from western Russia. Sequence information on an HPAI A(H5N6) virus found in a common gull in western Russia in October 2018 suggests that the virus clusters within clade 2.3.4.4c and is closely related to viruses that transmitted zoonotically in China. An increasing number of outbreaks in poultry and wild birds in Asia, Africa and the Middle East was observed during the time period for this report. Currently there is no evidence of a new HPAI virus incursion from Asia into Europe. However, passive surveillance systems may not be sensitive enough if the prevalence or case fatality in wild birds is very low. Nevertheless, it is important to encourage and maintain a certain level of passive surveillance in Europe testing single sick or dead wild birds and birds of prey as they may be sensitive sentinel species for the presence of HPAI virus in the environment. A well‐targeted active surveillance might complement passive surveillance to collect information on HPAI infectious status of apparently healthy wild bird populations.

Avian influenza is a viral disease that primarily infects wild and domestic birds, but it also can be transmitted to a variety of mammals. In 2006, the United States of America Departments of Agriculture and Interior designed a large-scale, interagency surveillance effort that sought to determine if highly pathogenic avian influenza viruses were present in wild bird populations within the United States of America. This program, combined with the Canadian and Mexican surveillance programs, represented the largest, coordinated wildlife disease surveillance program ever implemented. Here we analyze data from 197,885 samples that were collected from over 200 wild bird species. While the initial motivation for surveillance focused on highly pathogenic avian influenza, the scale of the data provided unprecedented information on the ecology of avian influenza viruses in the United States, avian influenza virus host associations, and avian influenza prevalence in wild birds over time. Ultimately, significant advances in our knowledge of avian influenza will depend on both large-scale surveillance efforts and on focused research studies.

The emergence of highly pathogenic H5N1 avian influenza poses a significant threat to human and animal health worldwide. This summary provides an overview of the surveillance efforts implemented in Peru to combat the spread of H5N1 avian influenza. Joint efforts between the authority, the productive sector, and academia date back to the first influenza outbreak in Chile in 2002. Since then, the government has been developing intense clinical and serological surveillance in the domestic birds and poultry industry. In parallel, the university has been carrying out important research to identify and typify the viruses that circulate in the resident and migratory wild bird populations of the Peruvian coast, having detected and identified during these years around 50 strains of influenza viruses of 10 different hemagglutinin subtypes and 8 neuraminidases, a single strain of the low pathogenicity H7N3 subtype. Until then, an H5-type virus had never been detected in wild birds. With the arrival of the virus in North America, a comprehensive response was developed in which the key components of the surveillance program included active and passive clinical surveillance in wild bird populations, commercial poultry, and backyard and game bird populations. Regarding surveillance of wild birds, the authority has received 238 notifications, of which 64 were confirmed positive, from 15 regions. In the Avian Pathology Laboratory of the UNMSM, actions were carried out to support the active surveillance of wild birds of the Peruvian coast in the impact zones for poultry farming, analyzing 405 samples of fresh feces from 41 species of asymptomatic coastal aquatic wild birds, being positive 12 (2.96\%). Additionally, 45 samples of wild birds with suspicious symptoms were analyzed and sent by different government institutions (SENASA, SERFOR, SERNAMP), with 19 (42\%) being confirmed positive. Regarding domestic bird populations, 1,676 notifications have been made to SENASA, of which 194 were positive for the H5N1 virus in 13 country regions. On the other hand, the Avian Pathology Lab received 16 confirmed positive cases by PCR and viral isolation in SPF embryonated eggs from ducks, quails, layers, native birds, and one case of turkeys. The complete genome analysis of 09 strains of wild birds, 04 of domestic birds, and one of sea lions has been carried out. Analysis of new samples is in process. NGS analysis has identified the IA H5N1 clade 2.3.4.4b virus; however, it has been found that the Peruvian strains are lining up in a group together with the Chilean strains. All these activities are possible to carry out thanks to the financial support of national and international institutions: NAMRU, Concytec-World Bank, Peruvian Poultry Association, and ALA-US Poultry. The high vulnerability of poultry populations in the country is due to its location along the coast, where tens of thousands of dead wild birds have fallen, in addition to being surrounded by a very high population of ducks, fighting, and backyard birds. The government determined emergency vaccination, as well as the continuation of clinical and virological surveillance in vaccinated and unvaccinated poultry populations. SENASA has been evaluating the protection of approved vaccines, both by the serological response with hemagglutination inhibition tests using local antigens and by challenge. The industry has responded by significantly increasing the levels of structural and operational biosafety, as well as directly supporting control actions at the regional level. Since March, no outbreaks have been reported in industrially farmed birds.

BackgroundThe introduction of multiple avian influenza virus (AIV) subtypes into Nigeria has resulted in several poultry outbreaks purportedly linked to trade and wild birds. The role of wild birds in perpetuating AIV in Nigeria was, therefore, elucidated.MethodsA cross‐sectional study was conducted among wild aquatic bird species at the Hadejia‐Nguru wetlands in Northeastern Nigeria between March and April 2022. A total of 452 swabs (226 cloacae and 226 oropharyngeal) were collected using a mist net to capture the birds. These samples were tested by RT‐qPCR, followed by sequencing.ResultsHighly pathogenic AIV of the H5N1 subtype was identified in clinically healthy wild bird species, namely, African jacana, ruff, spur‐winged goose, squared‐tailed nightjar, white‐faced whistling ducks, and white stork. A prevalence of 11.1% (25/226) was recorded. Phylogenetic analysis of the complete HA gene segment indicated the presence of clade 2.3.4.4b. However, these H5N1 viruses characterized from these wild birds cluster separately from the H5N1 viruses characterized in Nigerian poultry since early 2021. Specifically, the viruses form two distinct genetic groups both linked with the Eurasian H5N1 gene pool but likely resulting from two distinct introductions of the virus in the region. Whole‐genome characterization of the viruses reveals the presence of mammalian adaptive marker E627K in two Afro‐tropical resident aquatic ducks. This has zoonotic potential.ConclusionOur findings highlight the key role of surveillance in wild birds to monitor the diversity of viruses in this area, provide the foundations of epidemiological understanding, and facilitate risk assessment.

The current high pathogenicity avian influenza (HPAI) H5 panzootic is having a profound impact on the poultry industry and wildlife.1 While lineage 2.3.4.4b is of current concern, HPAI H5 emerged in poultry in 1996 and has caused outbreaks in wild bird populations episodically since 2005.2 The epidemiology of this virus has changed substantially with the emergence of new lineages, as exampled by Clade 2 viruses that caused the first wild bird mass mortality event at Qinghai Lake, China in 2005.3 A novel lineage emerged in 2014 (2.3.4.4), which has diversified and caused substantial mortality, including mass mortality events of wild birds in 2014, 2016 and 2021–present, along with ongoing outbreaks in poultry in Eurasia and North America.2 Understanding viral incursion risk following the emergence of novel lineages of HPAI with their own specific phenotype is of crucial importance in preventing incursion events, improving biosecurity to protect poultry and responding to wild bird outbreaks. The viral incursion into North America in December 2021 was not detected until outbreaks occurred in poultry.4 The recent incursion into South America, in November 2022, was only detected following mass mortality events.5 Wild migratory waterfowl have been predominantly implicated in the re-occuring incursions into Europe and Africa.6 However, there are few migratory waterfowl linking the Nearctic and Palearctic, as well as North and South America, suggesting that the long-distance dispersal of lineage 2.3.4.4b HPAI may rely on additional bird groups other than waterfowl (e.g., Günther et al.7). Lineage 2.3.4.4b has now been detected on all continents except Australia and Antarctica.8 HPAI incursion risk to Australia has previously been considered low due to the absence of waterfowl species that migrate beyond Australia9 (Figure 1), as also exemplified from influenza genomic surveillance.10 Still, annually, millions of migratory seabirds and shorebirds migrate from Asia and North America to Australia (Figure 1). Some of these species have been shown to be part of the avian influenza reservoir community11 and potentially survive and move HPAI viruses.12 To reveal whether a viral incursion may have occurred in Australia in 2022 with the arrival of wild migratory sea- and shorebirds, we investigated 817 migratory birds of the order Charadriiformes and Procelariformes, in September–December 2022. Specifically, we captured and sampled Short-tailed Shearwaters (Puffinus tenuirostris, n = 233) upon their arrival from the northern Pacific to a breeding colony on Philip Island, Victoria, and 12 Asian-breeding migratory shorebird species at major non-breeding sites in Roebuck Bay and 80 mile beach, Western Australia (n = 509) including Bar-tailed Godwit (Limosa lapponica, n = 72), Black-tailed Godwit (Limosa limosa, n = 14), Curlew Sandpiper (Calidris ferruginea, n = 23), Great Knot (Calidris tenuirostris, n = 71), Red Knot (Calidris canutus, n = 45), Red-necked Stint (Calidris ruficollis, n = 102), Sanderling (Calidris alba, n = 3), Ruddy Turnstone (Arenaria interpres, n = 25), Grey-tailed Tattler (Tringa brevipes, n = 50), Terek Sandpiper (Xenus cinereus, n = 50), Greater Sandplover (Charadrius leschenaultia, n = 49), Lesser Sandplover (Charadrius mongolus, n = 3) and Gull-billed Tern (Gelochelidon nilotica, n = 1). Finally, we also sampled Ruddy Turnstones at a non-breeding site on King Island, Tasmania (n = 75) (Figure 1). Capture, banding and sampling were conducted under Victorian Wader Study Group's ABBBS authority 8001, Deakin University animal ethics committee (B39-2019), Department of Primary Industries and Regional Development WA (20-4-10) and Department of Natural Resources and Environment (5/2019–2020). All samples were negative for influenza A virus by qPCR, following Wille et al.11 Twenty-five serum samples tested positive for anti-NP antibodies using a commercial ELISA (given an S/N cut off of 0.5), which fell within the previously reported seroprevalence of the species that tested positive11: Red-necked Stint (8/102), Red Knot (4/45), Ruddy Turnstone (3/75) and Short-tailed Shearwater (10/231). All sera samples positive by anti-NP ELISA were negative on a subsequent hemagglutination inhibition (HI) assay using a lineage 2.3.4.4b candidate vaccine virus A/Astrakhan/3212/2020(H5N8)13 following Wille et al.12 A candidate vaccine virus is a 6:2 recombinant virus on an A/Puerto Rico/8/1934(H1N1)(PR8) backbone with the multi-basic cleavage site removed. In addition to the absence of HPAI and antibodies against HPAI lineage 2.3.4.4.b in the sampled migrants, there were neither indications of increased mortality in any wild birds nor reports of unusual mortality in poultry across Australia. For Australia as for other regions in the world, HPAI incursion risk hinges on a combination of factors, including wild bird migration, virus pathogenicity in wild birds (notably whether wild birds are able to migrate while infected) and outbreaks and virus circulation in neighbouring regions (particularly at key stopover sites for migratory birds). That there was no incursion of HPAI in Australia in 2022 despite the arrival of millions of migratory birds, the capacity of wild birds to disperse this virus large distances (e.g., Caliendo et al.4), the apparent widening of the virus' host reservoir beyond waterfowl7, 8, 14 and high levels of HPAI activity in Asian countries along the East Asian Australasian flyway8 is unclear and warrants further investigation. As the spatial distribution and intensity of HPAI H5 outbreaks in birds has increased, we have seen a corresponding increase in the number of mammalian cases, including human cases.1 There has also been indication of mammal-to-mammal transmission for the first time since the emergence of this lineage,15 such that this avian panzootic has important implications for humans. Australia will again enter a high-risk period when the major bird migrations into the country take place between August and November 2023. Continued surveillance is critical for early detection and rapid response, and as such, we call for enhanced surveillance of Australian wild birds to match heightened incursion risk in the second half of 2023. Michelle Wille: Conceptualization; formal analysis; investigation; methodology; project administration; writing - original draft; writing - review and editing. Marcel Klaassen: Conceptualization; formal analysis; investigation; methodology; writing - original draft; writing - review and editing. We wish to acknowledge all those who contributed to bird capture and sample collection including members of Philip Island Nature Parks, Victorian Wader Study Group, Australian Wader Study Group, Broome Bird Observatory. Specifically, we would like to highlight the contributions of Robyn Atkinson, David Boyle, Robert Bush, Tegan Douglas, Richard DuFeu, Teagan Fitzwater, Roz Jessop, Hiske Klaassen, Grace Maglio, Toby Ross, Duncan Sutherland, Teri Visentin and Cassandra Wittwer. Research in Marcel Klaassen's lab is undertaken with support from Australian Research Council (ARC) Discovery Project Grant DP19010186. Michelle Wille is funded by an ARC Discovery Early Career Research Award (DE200100977). The WHO Collaborating Centre for Reference and Research on Influenza is funded by the Australian Department of Health. This study contributes to the aims of the National Avian Influenza Wild Bird Surveillance program. The authors declare no conflict of interest. The peer review history for this article is available at https://publons.com/publon/10.1111/irv.13118. The data that support the findings of this study are available from the corresponding author upon reasonable request.

The role wild bird species play in the transmission and ecology of avian influenza virus (AIV) is well established; however, there are significant gaps in our understanding of the worldwide distribution of these viruses, specifically about the prevalence and/or significance of AIV in Central and South America. As part of an assessment of the ecology of AIV in Guatemala, we conducted active surveillance in wild birds on the Pacific and Atlantic coasts. Cloacal and tracheal swab samples taken from resident and migratory wild birds were collected from February 2007 to January 2010.1913 samples were collected and virus was detected by real time RT-PCR (rRT-PCR) in 28 swab samples from ducks (Anas discors). Virus isolation was attempted for these positive samples, and 15 isolates were obtained from the migratory duck species Blue-winged teal. The subtypes identified included H7N9, H11N2, H3N8, H5N3, H8N4, and H5N4. Phylogenetic analysis of the viral sequences revealed that AIV isolates are highly similar to viruses from the North American lineage suggesting that bird migration dictates the ecology of these viruses in the Guatemalan bird population.

Novel H7N7 avian influenza viruses detected in migratory wild birds in eastern China between 2018 and 2020

Korea is located within the East Asian-Australian flyway of wild migratory birds during the fall and winter seasons. Consequently, the likelihood of introduction of numerous subtypes and pathotypes of the Avian influenza (AI) virus to Korea has been thought to be very high. In the current study, we surveyed wild bird feces for the presence of AI virus that had been introduced to Korea between September 2017 and February 2018. To identify and characterize the AI virus, we employed commonly used methods, namely, virus isolation (VI) via egg inoculation, real-time reverse transcription-polymerase chain reaction (rRT-PCR), conventional RT-PCR (cRT-PCR) and a newly developed next generation sequencing (NGS) approach. In this study, 124 out of 11,145 fresh samples of wild migratory birds tested were rRT-PCR positive; only 52.0% of VI positive samples were determined as positive by rRT-PCR from fecal supernatant. Fifty AI virus specimens were isolated from fresh fecal samples and typed. The cRT-PCR subtyping results mostly coincided with the NGS results, although NGS detected the presence of 11 HA genes and four NA genes that were not detected by cRT-PCR. NGS analysis confirmed that 12% of the identified viruses were mixed-subtypes which were not detected by cRT-PCR. Prevention of the occurrence of AI virus requires a workflow for rapid and accurate virus detection and verification. However, conventional methods of detection have some limitations. Therefore, different methods should be combined for optimal surveillance, and further studies are needed in aspect of the introduction and application of new methods such as NGS.

: Avian influenza viruses (AIV) have been isolated from a wide range of domestic and wild birds. Wildbirds, predominantly ducks, geese and gulls form the reservoir of AIV in nature. The viruses in wild bird populationsare a potential source of widespread infections in poultry. Active surveillance for AIV infection provides informationregarding AIV distribution, and global AIV surveillance can play a key role in the early recognition of highly pathogenicavian influenza (HPAI). Since 2003 in Korea, there have been four H5N1 HPAI outbreaks caused by clade 2.5, 2.2and 2.3.2. Therefore, improvement of AIV surveillance strategy is required to detect HPAI viruses effectively. Thisarticle deals with the major events establishing the role of wild birds in the natural history of influenza in Korea.We highlighted the need for continuous surveillance in wild birds and characterization of these viruses to understandAIV epidemiology and host ecology in Korea.Keywords : avian influenza, epidemiology, poultry, surveillance, wild bird