Avian influenza
2017; Wiley; Volume: 15; Issue: 10 Linguagem: Inglês
10.2903/j.efsa.2017.4991
ISSN1831-4732
AutoresSimon J. More, Dominique Bicout, Anette Bøtner, Andrew Butterworth, Paolo Calistri, Klaus Depner, S.A. Edwards, Bruno Garin‐Bastuji, Margaret Good, Christian Gortázar, Virginie Michel, Miguel Ángel Miranda Chueca, Søren Saxmose Nielsen, Mohan Raj, Liisa Sihvonen, H.A.M. Spoolder, Hans‐Hermann Thulke, Antonio Velarde, Preben Willeberg, Christoph Winckler, Andrew C. Breed, Adam Brouwer, Matthieu Guillemain, Timm Harder, Isabella Monne, Helen Clare Roberts, Francesca Baldinelli, Federica Barrucci, Chiara Fabris, Laura Martino, Olaf Mosbach‐Schulz, Frank Verdonck, Joana Morgado, Arjan Stegeman,
Tópico(s)Viral gastroenteritis research and epidemiology
ResumoEFSA JournalVolume 15, Issue 10 e04991 Scientific OpinionOpen Access Avian influenza EFSA Panel on Animal Health and Welfare (AHAW), EFSA Panel on Animal Health and Welfare (AHAW)Search for more papers by this authorSimon More, Simon MoreSearch for more papers by this authorDominique Bicout, Dominique BicoutSearch for more papers by this authorAnette Bøtner, Anette BøtnerSearch for more papers by this authorAndrew Butterworth, Andrew ButterworthSearch for more papers by this authorPaolo Calistri, Paolo CalistriSearch for more papers by this authorKlaus Depner, Klaus DepnerSearch for more papers by this authorSandra Edwards, Sandra EdwardsSearch for more papers by this authorBruno Garin-Bastuji, Bruno Garin-BastujiSearch for more papers by this authorMargaret Good, Margaret GoodSearch for more papers by this authorChristian Gortázar Schmidt, Christian Gortázar SchmidtSearch for more papers by this authorVirginie Michel, Virginie MichelSearch for more papers by this authorMiguel Angel Miranda, Miguel Angel MirandaSearch for more papers by this authorSøren Saxmose Nielsen, Søren Saxmose NielsenSearch for more papers by this authorMohan Raj, Mohan RajSearch for more papers by this authorLiisa Sihvonen, Liisa SihvonenSearch for more papers by this authorHans Spoolder, Hans SpoolderSearch for more papers by this authorHans-Hermann Thulke, Hans-Hermann ThulkeSearch for more papers by this authorAntonio Velarde, Antonio VelardeSearch for more papers by this authorPreben Willeberg, Preben WillebergSearch for more papers by this authorChristoph Winckler, Christoph WincklerSearch for more papers by this authorAndrew Breed, Andrew BreedSearch for more papers by this authorAdam Brouwer, Adam BrouwerSearch for more papers by this authorMatthieu Guillemain, Matthieu GuillemainSearch for more papers by this authorTimm Harder, Timm HarderSearch for more papers by this authorIsabella Monne, Isabella MonneSearch for more papers by this authorHelen Roberts, Helen RobertsSearch for more papers by this authorFrancesca Baldinelli, Francesca BaldinelliSearch for more papers by this authorFederica Barrucci, Federica BarrucciSearch for more papers by this authorChiara Fabris, Chiara FabrisSearch for more papers by this authorLaura Martino, Laura MartinoSearch for more papers by this authorOlaf Mosbach-Schulz, Olaf Mosbach-SchulzSearch for more papers by this authorFrank Verdonck, Frank VerdonckSearch for more papers by this authorJoana Morgado, Joana MorgadoSearch for more papers by this authorJan Arend Stegeman, Jan Arend StegemanSearch for more papers by this author EFSA Panel on Animal Health and Welfare (AHAW), EFSA Panel on Animal Health and Welfare (AHAW)Search for more papers by this authorSimon More, Simon MoreSearch for more papers by this authorDominique Bicout, Dominique BicoutSearch for more papers by this authorAnette Bøtner, Anette BøtnerSearch for more papers by this authorAndrew Butterworth, Andrew ButterworthSearch for more papers by this authorPaolo Calistri, Paolo CalistriSearch for more papers by this authorKlaus Depner, Klaus DepnerSearch for more papers by this authorSandra Edwards, Sandra EdwardsSearch for more papers by this authorBruno Garin-Bastuji, Bruno Garin-BastujiSearch for more papers by this authorMargaret Good, Margaret GoodSearch for more papers by this authorChristian Gortázar Schmidt, Christian Gortázar SchmidtSearch for more papers by this authorVirginie Michel, Virginie MichelSearch for more papers by this authorMiguel Angel Miranda, Miguel Angel MirandaSearch for more papers by this authorSøren Saxmose Nielsen, Søren Saxmose NielsenSearch for more papers by this authorMohan Raj, Mohan RajSearch for more papers by this authorLiisa Sihvonen, Liisa SihvonenSearch for more papers by this authorHans Spoolder, Hans SpoolderSearch for more papers by this authorHans-Hermann Thulke, Hans-Hermann ThulkeSearch for more papers by this authorAntonio Velarde, Antonio VelardeSearch for more papers by this authorPreben Willeberg, Preben WillebergSearch for more papers by this authorChristoph Winckler, Christoph WincklerSearch for more papers by this authorAndrew Breed, Andrew BreedSearch for more papers by this authorAdam Brouwer, Adam BrouwerSearch for more papers by this authorMatthieu Guillemain, Matthieu GuillemainSearch for more papers by this authorTimm Harder, Timm HarderSearch for more papers by this authorIsabella Monne, Isabella MonneSearch for more papers by this authorHelen Roberts, Helen RobertsSearch for more papers by this authorFrancesca Baldinelli, Francesca BaldinelliSearch for more papers by this authorFederica Barrucci, Federica BarrucciSearch for more papers by this authorChiara Fabris, Chiara FabrisSearch for more papers by this authorLaura Martino, Laura MartinoSearch for more papers by this authorOlaf Mosbach-Schulz, Olaf Mosbach-SchulzSearch for more papers by this authorFrank Verdonck, Frank VerdonckSearch for more papers by this authorJoana Morgado, Joana MorgadoSearch for more papers by this authorJan Arend Stegeman, Jan Arend StegemanSearch for more papers by this author First published: 16 October 2017 https://doi.org/10.2903/j.efsa.2017.4991Citations: 33 Correspondence: ALPHA@efsa.europa.eu Requestor: European Commission Question numbers: EFSA-Q-2015-00214 and EFSA-Q-2016-00348 Panel members: Dominique Bicout, Anette Bøtner, Andrew Butterworth, Paolo Calistri, Klaus Depner, Sandra Edwards, Bruno Garin-Bastuji, Margaret Good, Christian Gortázar Schmidt, Virginie Michel, Miguel Angel Miranda, Simon More, Søren Saxmose Nielsen, Mohan Raj, Liisa Sihvonen, Hans Spoolder, Jan Arend Stegeman, Hans-Hermann Thulke, Antonio Velarde, Preben Willeberg and Christoph Winckler. Acknowledgements: The Panel wishes to thank the members of the Working Group on avian influenza: Dominique Bicout, Andrew Breed, Adam Brouwer, Anette Bøtner, Jeroen Dewulf, Matthieu Guillemain, Timm Harder, Andrew David Hart, Isabella Monne, Helen Roberts, Jan Arend Stegeman, Hans-Hermann Thulke, Martin Wikelski for the preparatory work on this scientific output and the hearing experts: Patrick Daniel, Teun Fabri, Nicolas Gaidet, Barbara Grabkowsky, Vittorio Guberti, Marie Guyot, Ursula Hoefle, Adeline Huneau Salaun, Thijs Kuiken, Hartmut Meyer, Virginie Michel, Ioana Neghirla, Éric Niqueux, Yali Si, Brigita Slavec, Krzysztof Smietanka, Christoph Staubach, Anna Luca Vescei, Josanne Verhagen, Sophie Von Dobschuetz and ECDC staff member Cornelia Adlhoch and the AI Consortium (Erasmus University, NL; Wageningen University, NL; Animal & Plant Health Agency, UK; Friederich-Loeffler-Institut, DE; Linnaeus University, SE; Istituto Zooprofilattico Sperimentale delle Venezie, IT) for the support provided to this scientific output and Adeline Huneau-Salaün, Anne Bronner for writing the Annex on the AI surveillance in France from 2012 to 2015. Amendment: This output has been updated to include data received from Finland after the date of publication. These do not impact on the overall outcomes. The original is available on request. Adopted: 14 September 2017 Amended: 14 December 2017 Reproduction of the images listed below is prohibited and permission must be sought directly from the copyright holder: Figure 1: © FAO This publication is linked to the following EFSA Journal article: http://onlinelibrary.wiley.com/doi/10.2903/j.efsa.2017.5018/full This publication is linked to the following EFSA Supporting Publications article: http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2017.EN-1282/full, http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2017.EN-1283/full, http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2017.EN-1284/full, http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2017.EN-1285/full, http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2017.EN-1286/full, http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2017.EN-1287/full AboutSectionsPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Abstract Previous introductions of highly pathogenic avian influenza virus (HPAIV) to the EU were most likely via migratory wild birds. A mathematical model has been developed which indicated that virus amplification and spread may take place when wild bird populations of sufficient size within EU become infected. Low pathogenic avian influenza virus (LPAIV) may reach similar maximum prevalence levels in wild bird populations to HPAIV but the risk of LPAIV infection of a poultry holding was estimated to be lower than that of HPAIV. Only few non-wild bird pathways were identified having a non-negligible risk of AI introduction. The transmission rate between animals within a flock is assessed to be higher for HPAIV than LPAIV. In very few cases, it could be proven that HPAI outbreaks were caused by intrinsic mutation of LPAIV to HPAIV but current knowledge does not allow a prediction as to if, and when this could occur. In gallinaceous poultry, passive surveillance through notification of suspicious clinical signs/mortality was identified as the most effective method for early detection of HPAI outbreaks. For effective surveillance in anseriform poultry, passive surveillance through notification of suspicious clinical signs/mortality needs to be accompanied by serological surveillance and/or a virological surveillance programme of birds found dead (bucket sampling). Serosurveillance is unfit for early warning of LPAI outbreaks at the individual holding level but could be effective in tracing clusters of LPAIV-infected holdings. In wild birds, passive surveillance is an appropriate method for HPAIV surveillance if the HPAIV infections are associated with mortality whereas active wild bird surveillance has a very low efficiency for detecting HPAIV. Experts estimated and emphasised the effect of implementing specific biosecurity measures on reducing the probability of AIV entering into a poultry holding. Human diligence is pivotal to select, implement and maintain specific, effective biosecurity measures. Summary As a follow-up to the highly pathogenic avian influenza (HPAI) H5N8 virus outbreaks in 2014/2015, the European Food Safety Authority (EFSA) has been requested by the European Commission to assess the risk of HPAI introduction into the European Union (EU) and into poultry holdings via wild birds and other possible entry routes, to assess the risk of low pathogenic avian influenza virus (LPAIV) introduction from the wild bird reservoir into poultry holdings and to assess the suitability of biosecurity, early detection and protection measures in poultry if there is HPAI occurrence in wild birds and the surveillance strategy. Additional questions were submitted to EFSA after the avian influenza (AI) outbreaks in France in 2015/2016, mainly to assess AI transmission characteristics and to analyse the mutation of LPAI to HPAI viruses as well as widening the questions on AI introduction and analysis of surveillance tools. Mapping of HPAI and LPAI outbreaks In the last decade, several clades of highly pathogenic avian influenza virus (HPAIV) H5 and members of the Eurasian lineage of HPAIV H7 have been detected in Europe. HPAIV H5 affected poultry and wild birds, whereas HPAIV H7 was only found in poultry. Distinct HPAI clades of goose/Guangdong-like H5 subtype viruses are present in poultry populations in several subcontinental regions outside the EU, e.g. in South-East and possibly Central Asia, China, Egypt and West Africa. None of the HPAI viruses recently detected in the EU revealed significant zoonotic potential, although highly zoonotic HPAIV are circulating in Asia (H7N9, H5N6 and H5N1) and in Egypt (H5N1) that may be introduced into Europe. The descendants of the original goose/Guangdong (gs/GD) HPAIV H5 clades 2.2.1.2, 2.3.2.1c and 2.3.4.4 were selected for detailed analysis of introduction via wild birds as these were considered the main virus types that could cause outbreaks in the EU in the near future. H5 and H7 LPAI viruses are endemic in the European wild bird population. Potentially zoonotic LPAI viruses of subtype H9N2 (G1 lineage) are endemic in poultry in many parts of Asia, the Middle East and northern Africa. Although these viruses have not been detected so far in Europe, introduction is possible. LPAI viruses were analysed as one further group as in this scientific opinion they all have a similar impact on poultry. Establishing a harmonised data collection system, integrating outbreak notification data, wild bird findings and epidemiological parameters, will aid in providing timely epidemiological analysis within the EU. It is also recommended that observations of global AI-related epidemiology fare shared in due time to inform competent authorities and guide strategic preventive measures. HPAI introduction via migratory and residential wild birds Outbreaks of HPAI H5 in poultry in the EU since 2006 were initiated by primary incursions of infected migratory wild birds into Europe, but intrinsic generation from an LPAI precursor virus and secondary spread between poultry holdings has also been observed. Four potential different geographical routes for the entry of wild birds into the EU were defined here: the north-eastern route (NE; EU border with Russia and Belarus), eastern route (E, EU border with Ukraine, Moldova, Black Sea, Turkey until the southern border of Turkey), southern route (S, EU border from the southern border of Turkey to the northern border of Portugal) and north-western route (NW; EU border from north Portugal to north Russia). According to results obtained from the epizootic model generated in this opinion, the NE and E routes have been associated with a high risk of H5 HPAIV-infected wild birds entering the EU. No H5 HPAIV incursion has been observed so far from the S and NW routes. Upon introduction of HPAIV into a wild bird population within the EU, a critical number of wild birds is required before virus amplification and further wild bird-associated geographical spread of the virus may take place. The lower the number of susceptible water birds entering daily, the later the prevalence starts to increase. Some scenarios are described in detail in the opinion to relative importance of different parameters, whereas extrapolation of the numbers to the real world is difficult given the model assumptions and high uncertainty around the data. An association was identified between the HPAIV occurrence in wild birds and the likelihood of infection of poultry holdings, which is supported by the association between detections in wild birds and poultry in the field. According to expert opinion, prevention of access of poultry to water bodies could result in a threefold reduction in HPAI entry probability. Combining this biosecurity measure with confining poultry to indoor housing was estimated to further reduce the HPAI entry probability twofold, and adding routine or high biosecurity would result in a further reduction of 4- and 44-fold, respectively. The estimated effect of biosecurity measures was considered independently of the HPAI virus characteristics. LPAI introduction via migratory and/or residential wild birds For LPAIV, endemically infected wild bird populations play an important role as a source of primary incursions, but secondary spread by undiagnosed infected poultry flocks must be considered as well. According to results obtained from the epizootic model, LPAIV can reach similar maximum prevalence levels in wild bird populations when compared with HPAIV. At the same prevalence in the wild bird reservoir, the risk of LPAIV infection of a poultry holding was estimated to be lower than that of HPAIV. Experts considered the effect of implementing biosecurity on lowering the probability of LPAIV entry into a holding similar to that of HPAIV. HPAI and LPAI introduction via non-wild bird pathways The risk of HPAIV and LPAIV introduction into the EU through non-wild bird pathways is estimated to be lower compared with the wild bird pathway. The only non-wild bird pathways that were considered to have a non-negligible risk of HPAI introduction are intra-EU movements and Third country trade of semen, intra-EU movements of manure originating from holdings with Anseriformes species. For LPAI, the only non-wild bird pathways that were considered to have a non-negligible risk of introduction are intra-EU movements of live poultry and day-old chicks, intra-EU movements of manure originating from holdings with any species. Introduction of AI into a poultry holding via feed and bedding was considered non-negligible when accessible by wild birds during storage or any point during the transport route. Illegal introductions of HPAIV-infected commodities (e.g. birds of prey, pet birds, unprocessed poultry meat) have been detected at the EU border. Risk assessments would benefit from studies analysing virus perseverance in semen and faeces/manure (unprocessed, storage, composting, effect of cleaning and disinfection procedures). It is also recommended that Member States (MSs) trading poultry semen report their national rules (based on OIE recommendations) and an estimate of the volumes traded so that a risk-based approach can be developed to assess the risk of AI introduction and spread via semen. HPAI and LPAI transmission and spread The transmission rate between animals within a flock is assessed to be higher for HPAI viruses than LPAI viruses. In most cases, LPAIV remains restricted to a single farm, although horizontal spread has been observed in several occasions. Spread of HPAI viruses between farms is highly likely in the absence of control measures. It is recommended to perform epidemiological studies to obtain quantitative information on between-flock transmission and to assess the effect of risk factors influencing between-flock and between-farm spread. Collection of standardised epidemiological data at the EU level from the holdings (e.g. location) and their houses (e.g. affected or not, number of susceptible birds, population structure) would be required on an ongoing basis. Mutation from LPAI to HPAI In very few cases, it could be proven that HPAI outbreaks were caused by intrinsic mutation of LPAIV to HPAIV and since 2005 the secondary spread of such HPAI viruses in the EU was limited except for one event, which has led to recurrent HPAIV outbreaks in a single region of France. No specific factors related to host species, environmental conditions or viral lineage were identified and likewise no molecular markers that would be useful predictors of increased risk of a specific LPAIV to mutate to an HPAI phenotype were identified. However, emergence of HPAI viruses from LPAI precursors in Europe has occurred more frequently for LPAI viruses of the H7 subtype than H5. Current knowledge does not allow a prediction as to if, and when, LPAI will mutate to HPAI. Standardising and connecting virological and epidemiological data collections across the EU and supporting research that applies a holistic approach to increase our ability to assess the role of specific viral, environmental and host factors on the pathogenicity evolution is recommended. HPAI and LPAI surveillance and early detection Introduction of HPAIV in gallinaceous poultry populations inevitably results in severe clinical disease and high mortality, whereas the clinical manifestation and mortality in anseriform poultry depends on the phenotypic characteristics of a HPAI virus. Passive surveillance through notification of suspicious clinical signs/mortality is the most effective method for early detection of HPAI outbreaks in gallinaceous poultry. For effective surveillance in anseriform poultry, passive surveillance through notification of suspicious clinical signs/mortality needs to be accompanied by active serological surveillance and/or a virological surveillance programme of birds found dead (bucket sampling). Pooling of such samples for polymerase chain reaction (PCR)-directed diagnosis may be useful. Subclinically infected domestic Anseriformes have a higher likelihood of continued spreading of HPAIV when compared with clinically infected gallinaceous poultry, because it may go unnoticed. Therefore, MSs are recommended to focus their annual serological surveillance programme on Anseriformes and game bird populations. Recognition and reporting of suspicion, sampling, testing and reporting of results is required to be done in a timely manner. Risk-based surveillance is useful as it targets flocks where the likelihood of avian influenza virus (AIV) introduction is considered to be higher than average, although there is limited quantitative (EU-wide) evidence to weigh the risk factors. Reporting of risk-based surveillance approaches are not currently detailed enough to allow robust analysis and comparison of the results among MSs. There is currently a lack of data on non-affected holdings and houses within the affected regions, which is required in order to establish the magnitudes of risk of infection for the various potential risk factors, such as location, holding- and flock sizes, biosecurity measures, etc. It is recommended to quantify the weighting of the risk factors used to design risk-based surveillance and implement a detailed description of their use in national surveillance plans to facilitate analysis of the results and comparison of results among MSs. The current serological surveillance programme is useful to detect major changes in regional LPAIV occurrence but results in the detection of active H5 or H7 infection only in a minority (around 20%) of follow-ups conducted. The serological surveillance is unfit for early warning of LPAI outbreaks at the individual holding level but could be effective in tracing clusters of LPAIV-infected holdings. Therefore, serosurveillance should aim at detecting clusters of LPAIV-infected farms in order to identify those LPAI events with continuous between farm spread. Epidemiological follow-up (tracing on/back) of serologically positive holdings should be carried out to determine if there is clustering of AIV-infected holdings/flocks in space and/or time regardless of whether the seropositive birds are still at the holding or whether active virus infection has been detected. If the group (i.e. epidemiological unit such as shed or flock) of poultry that were sampled for serology are not available for PCR testing, then any other poultry (in particular seronegative birds) still remaining on that holding should be tested. Passive surveillance is an appropriate method for HPAI surveillance in wild birds if the HPAIV infections are associated with mortality. Active wild bird surveillance efficiency is very low in detecting HPAI. When HPAIV has been detected in poultry within a given geographical area, active wild bird surveillance could play a role in detecting HPAIV infections in wild birds that are not associated with mortality as a possible source of virus introduction. A relative risk map of predicted H5 HPAIV occurrences in wild birds in Europe has been generated based on the wild bird events reported between 2005 and 2017, which could contribute to identification of priority locations in the EU where targeted active wild bird surveillance could be implemented during wild bird migration periods. Targeted active wild bird surveillance through virology tests (swabbing) combined with enhanced passive surveillance at a few priority regions in the EU may detect, if infection prevalence and sample sizes are sufficient, the presence of circulating AIV when these do not cause massive mortality among these birds. Serological analysis would be useful to increase our understanding of HPAIV dynamics in wild bird populations. Biosecurity to prevent HPAI and LPAI entry and spread Experts indicated that biosecurity measures play a key role in preventing AI spread from wild birds to poultry. Human diligence is pivotal to select, implement and maintain effective biosecurity measures. While certain general biosecurity principles universally apply to poultry holdings, unique features for each holding need to be considered for optimised protection. According to expert opinion, the most feasible, sustainable and efficient measure to reduce the risk of AI entry in indoor poultry holdings is to prevent direct and indirect wild bird contact. Other measures with a high feasibility and sustainability are separation of waterfowl from other poultry species, provision of potable drinking water instead of surface water, the implementation of a hygiene lock for each poultry house, and biosecurity training of staff. Outdoor poultry holdings bear an increased risk of AI incursions and the applicable biosecurity measures are more limited. According to expert opinion, restricting access of persons and providing biosecurity training are the most feasible, sustainable and efficient measures to reduce the risk of AI entry and spread in commercial holdings where poultry have access to outdoor areas. For backyard holdings, experts assigned biosecurity training the highest overall rank to prevent AI entry and spread. According to expert opinion, the highest ranked measures to prevent secondary spread of the virus are: to contain poultry and fomites (i.e. materials that were in contact with poultry) during transport, cleaning and disinfection of equipment, biosecurity training, cleaning and disinfection of transport vehicles, and the use of a hygiene lock for each poultry house. The risk of avian influenza virus (AIV) introduction and spread will remain high in production processes when: movement of animals, restricting access throughout the whole production cycle, and/or contact with wild birds is not reduced. It is recommended at all times to restrict wild bird access to poultry holdings, avoiding the presence of open water bodies on the premises, feed should be provided indoors only, to implement hygiene locks, restrict access of people, and to limit contacts to other poultry holdings. Professional staff of poultry holdings should attend general biosecurity training but also receive holding-specific biosecurity advice ideally from an expert (e.g. veterinarian) familiar with the particular holding. Also hobby keepers should receive information to achieve at least a minimal understanding of biosecurity to prevent entry and/or spread of AIV in their backyards and during markets and/or shows. Game bird hunting activities must be fully separated from rearing poultry and game birds should be tested for AI before release. Online biosecurity questionnaires could be used by farmers to check their current biosecurity level and subsequently to improve it based on the received feedback. During high-risk periods, it is recommended to prevent direct contact between wild birds and poultry through confinement, netting, or at least limitation of outdoor access area of domestic birds. Feed and water should be provided under a roof or a horizontal fabric. Biosecurity training and improved control of catching crews and other 'mobile' staff may be useful to limit indirect spread of HPAIV and LPAIV during large-scale operations in commercialised poultry holdings. Establishment of a control and monitoring area and risk zones There is no scientific evidence to guide the sizes of a control and monitoring zone upon finding HPAIV in wild birds because it depends on the dynamics of the epizootic and the infected bird species. It is recommended that control and in particular monitoring areas are set up based on the ecological habitat and flight distance of the infected wild bird species. Setting up small-sized restriction zones for the first cases at the beginning of a new wild bird epidemic may be instrumental in being able to implement increased surveillance activities in poultry in this zone. Informing poultry keepers on the detection of HPAIV in wild birds in the region will increase their awareness of the risk of virus introduction into their holding. In the progression of a wild bird epidemic, setting up wider zones, rather than a succession of small, restricted zones may be more appropriate. During an epidemic of HPAIV in wild birds, it is recommended that samples from new species and non-previously reported areas be tested. Testing in reported areas can be restricted to check viral presence in relation to an 'exit strategy' from measures implemented. Sharing data and expert opinion at national and EU level on exit strategies would aid in terms of harmonised and structured approaches as well as interpretation of available data. Collaboration between authorities and stakeholders is crucial. 1 Introduction 1.1 Background and Terms of Reference as provided by the requestor 1.1.1 EFSA-Q-2015-00214 (April 2015) The occurrence of highly pathogenic avian influenza (HPAI) outbreaks of the H5N8 subtype in Member States (MSs) triggered the immediate implementation of control measures according to Council Directive 2005/94/EC1. The Commission asked the European Food Safety Authority (EFSA) to issue a scientific report on the disease situation world-wide and to assess possible virus entry routes into the European Union (EU) poultry holdings with a particular view to the role played by wild migratory birds. Although there is knowledge about the direct or indirect migration routes from East Asia to Europe, several theories of HPAI H5N8 virus (and possibly other HPAI viruses) entry routes from East Asia into Eur
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