Urgent request on avian influenza
2017; Wiley; Volume: 15; Issue: 1 Linguagem: Inglês
10.2903/j.efsa.2016.4687
ISSN1831-4732
AutoresSimon J. More, Dominique Bicout, Anette Bøtner, Andrew Butterworth, Paolo Calistri, Klaus Depner, SA 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, Cornelia Adlhoch, Francesca Baldinelli, Andrew C. Breed, Adam Brouwer, Matthieu Guillemain, Timm Harder, Isabella Monne, Helen Clare Roberts, José Cortiñas Abrahantes, Olaf Mosbach‐Schulz, Frank Verdonck, Joana Morgado, Arjan Stegeman,
Tópico(s)Vector-Borne Animal Diseases
ResumoEFSA JournalVolume 15, Issue 1 e04687 StatementOpen Access Urgent request on avian influenza EFSA AHAW Panel (EFSA Panel on Animal Health and Welfare), EFSA AHAW Panel (EFSA Panel on Animal Health and Welfare)Search for more papers by this authorS More, S MoreSearch for more papers by this authorD Bicout, D BicoutSearch for more papers by this authorA Bøtner, A BøtnerSearch for more papers by this authorA Butterworth, A ButterworthSearch for more papers by this authorP Calistri, P CalistriSearch for more papers by this authorK Depner, K DepnerSearch for more papers by this authorS Edwards, S EdwardsSearch for more papers by this authorB Garin-Bastuji, B Garin-BastujiSearch for more papers by this authorM Good, M GoodSearch for more papers by this authorC Gortázar Schmidt, C Gortázar SchmidtSearch for more papers by this authorV Michel, V MichelSearch for more papers by this authorMA Miranda, MA MirandaSearch for more papers by this authorS Saxmose Nielsen, S Saxmose NielsenSearch for more papers by this authorM Raj, M RajSearch for more papers by this authorL Sihvonen, L SihvonenSearch for more papers by this authorH Spoolder, H SpoolderSearch for more papers by this authorHH Thulke, HH ThulkeSearch for more papers by this authorA Velarde, A VelardeSearch for more papers by this authorP Willeberg, P WillebergSearch for more papers by this authorC Winckler, C WincklerSearch for more papers by this authorC Adlhoch, C AdlhochSearch for more papers by this authorF Baldinelli, F BaldinelliSearch for more papers by this authorA Breed, A BreedSearch for more papers by this authorA Brouwer, A BrouwerSearch for more papers by this authorM Guillemain, M GuillemainSearch for more papers by this authorT Harder, T HarderSearch for more papers by this authorI Monne, I MonneSearch for more papers by this authorH Roberts, H RobertsSearch for more papers by this authorJ Cortinas Abrahantes, J Cortinas AbrahantesSearch for more papers by this authorO Mosbach-Schulz, O Mosbach-SchulzSearch for more papers by this authorF Verdonck, F VerdonckSearch for more papers by this authorJ Morgado, J MorgadoSearch for more papers by this authorA Stegeman, A StegemanSearch for more papers by this author EFSA AHAW Panel (EFSA Panel on Animal Health and Welfare), EFSA AHAW Panel (EFSA Panel on Animal Health and Welfare)Search for more papers by this authorS More, S MoreSearch for more papers by this authorD Bicout, D BicoutSearch for more papers by this authorA Bøtner, A BøtnerSearch for more papers by this authorA Butterworth, A ButterworthSearch for more papers by this authorP Calistri, P CalistriSearch for more papers by this authorK Depner, K DepnerSearch for more papers by this authorS Edwards, S EdwardsSearch for more papers by this authorB Garin-Bastuji, B Garin-BastujiSearch for more papers by this authorM Good, M GoodSearch for more papers by this authorC Gortázar Schmidt, C Gortázar SchmidtSearch for more papers by this authorV Michel, V MichelSearch for more papers by this authorMA Miranda, MA MirandaSearch for more papers by this authorS Saxmose Nielsen, S Saxmose NielsenSearch for more papers by this authorM Raj, M RajSearch for more papers by this authorL Sihvonen, L SihvonenSearch for more papers by this authorH Spoolder, H SpoolderSearch for more papers by this authorHH Thulke, HH ThulkeSearch for more papers by this authorA Velarde, A VelardeSearch for more papers by this authorP Willeberg, P WillebergSearch for more papers by this authorC Winckler, C WincklerSearch for more papers by this authorC Adlhoch, C AdlhochSearch for more papers by this authorF Baldinelli, F BaldinelliSearch for more papers by this authorA Breed, A BreedSearch for more papers by this authorA Brouwer, A BrouwerSearch for more papers by this authorM Guillemain, M GuillemainSearch for more papers by this authorT Harder, T HarderSearch for more papers by this authorI Monne, I MonneSearch for more papers by this authorH Roberts, H RobertsSearch for more papers by this authorJ Cortinas Abrahantes, J Cortinas AbrahantesSearch for more papers by this authorO Mosbach-Schulz, O Mosbach-SchulzSearch for more papers by this authorF Verdonck, F VerdonckSearch for more papers by this authorJ Morgado, J MorgadoSearch for more papers by this authorA Stegeman, A StegemanSearch for more papers by this author First published: 30 January 2017 https://doi.org/10.2903/j.efsa.2016.4687Citations: 4 Correspondence: ALPHA@efsa.europa.eu Requestor: European Commission Question number: EFSA-Q-2016-00777 Panel on Animal Health and Welfare (AHAW) 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 H. Thulke, Antonio Velarde, Preben Willeberg and Christoph Winckler. Acknowledgements: The Panel wishes to thank ECDC (Cornelia Adlhoch), EURL (Ian Brown, Pablo Alarcon, Adam Brouwer and Andrew Breed) and authorities of the affected Member States (Austria: Eveline Wodak and Andrea Höflechner; Croatia: Dražen Kneževic and Tihana Miškić; Denmark: Pernille Dahl Nielsen; Finland: Tiia Tuupanen and Kitty Schulman; France: Isabelle Guerry, Éric Niqueux, Aurdrey Schmitz, François-Xavier Briand and Claire Martenot; Germany: Christoph Staubach, Nicole Reimer, Patrick Wysocki and Franz Conraths; Hungary: Gábor Wyszoczky and Orsolya Dobó-Kiss; Italy: Paolo Mulatti; Netherlands: Marcel Spierenburg; Poland: Cwynar Przemysław and Iwona Wisniewska; Sweden: Annica Wallén Norell; Switzerland: Lukas Perler) for the input provided regarding the human and animal aspects of the current AI outbreaks in Europe; the hearing experts Patrick Daniel, Jeroen Dewulf, Barbara Grabkowsky and Thijs Kuiken for the input on biosecurity and wild bird aspects. Adopted: 15 September 2016 This article was previously published on the EFSA website in December 2016 as part of EFSA's crisis communication procedures. This publication is linked to the following EFSA Supporting Publications article: http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2016.EN-1142/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 Highly pathogenic avian influenza (HPAI) H5N8 is currently causing an epizootic in Europe, infecting many poultry holdings as well as captive and wild bird species in more than 10 countries. Given the clear clinical manifestation, passive surveillance is considered the most effective means of detecting infected wild and domestic birds. Testing samples from new species and non-previously reported areas is key to determine the geographic spread of HPAIV H5N8 2016 in wild birds. Testing limited numbers of dead wild birds in previously reported areas is useful when it is relevant to know whether the virus is still present in the area or not, e.g. before restrictive measures in poultry are to be lifted. To prevent introduction of HPAIV from wild birds into poultry, strict biosecurity implemented and maintained by the poultry farmers is the most important measure. Providing holding-specific biosecurity guidance is strongly recommended as it is expected to have a high impact on the achieved biosecurity level of the holding. This is preferably done during peace time to increase preparedness for future outbreaks. The location and size of control and in particular monitoring areas for poultry associated with positive wild bird findings are best based on knowledge of the wider habitat and flight distance of the affected wild bird species. It is recommended to increase awareness among poultry farmers in these established areas in order to enhance passive surveillance and to implement enhanced biosecurity measures including poultry confinement. There is no scientific evidence suggesting a different effectiveness of the protection measures on the introduction into poultry holdings and subsequent spread of HPAIV when applied to H5N8, H5N1 or other notifiable HPAI viruses. 1 Introduction 1.1 Background and Terms of Reference as provided by the requestor The European Commission has already requested1 the European Food Safety Authority (EFSA) to provide a scientific opinion on avian influenza (AI), assessing the risks for virus introduction of highly pathogenic avian influenza (HPAI) H5N8 and possibly other HPAI viruses into the European Union (EU) and the risks posed by these viruses to public and animal health. EFSA's work is in progress in relation to the risks posed by the H5N8 AIV to humans (TOR 2), in collaboration with ECDC and the EU Reference Laboratory for avian influenza in particular as regards the current evolving disease situation. EFSA has been requested also to assess the suitability of preventive and control measures laid down in several Commission decisions that were adopted in 2006 during the HPAI H5N1 occurrence in the EU (TOR 2). These measures include early detection systems, biosecurity, movement restrictions, additional zoning for poultry and certain products in relation to infected wild birds, as well as surveillance and are laid down in Decisions 2005/734/EC, 2006/563/EC and 2010/367/EU. It should be assessed, if they should equally be applied to other subtypes or clades of HPAI viruses, such as the H5N8 subtype, when they are identified in poultry and/or wild birds. The measures laid down in Decision 2006/415/EC should be assessed as well. The current occurrence of the HPAI H5N8 virus in wild birds and in poultry in several Member States makes management decisions in this respect even more urgent. In view of the rapidly evolving disease situation, the European Commission asked EFSA to focus and prioritise on the above issues and to produce an urgent partial reply in relation to the measures cited above and their suitability for the current situation. The European Commission would be grateful if EFSA could deliver such response by the end of the year 2016. 1.2 Interpretation of the Terms of Reference HPAI H5N8 virus has been isolated in poultry holdings, wild and captive birds in many Member States and in Switzerland between 28 October and 11 December 2016. This Statement provides a rapid and partial assessment of TOR2 from the mandate2 previously received from the European Commission, focussing on the question whether the measures laid down in the four Decisions that are based on HPAI H5N1 findings in wild birds can be equally applied to manage the current HPAI H5N8 outbreaks. A description of the detections in space and time as well as a list of affected wild bird species are provided in the first section of this Statement. The main genetic characteristics of the virus and the induced morbidity and mortality are analysed using the data available. The affected countries submitted data via the Animal Disease Notification System (ADNS) database and directly to EFSA, although it should be noted that this has been asked for at very short notice at a time when the countries were still focussing on managing the outbreaks. The data set currently available upon establishment of the current report may hence not be fully comprehensive. A more complete data collection will be done after the end of the epizootic period to underpin the scientific opinion that will be finalised in 2017. The characteristics of the circulating HPAI H5N8 virus and an analysis of what triggered virus detection in the field, are used to assess whether early detection in poultry and surveillance in poultry and wild birds could be applied similarly to HPAI H5N1 outbreaks, as described in the Decisions 2005/734/EC and 2010/367/EU, respectively. Based on this preliminary assessment, recommendations are provided that could help Member States in targeting surveillance for HPAI H5N8 in wild birds as an early warning for nearby poultry holdings, although more structured advice will be provided later in the full scientific opinion. The analysis of similarities and differences in HPAI H5N8 and HPAI H5N1 transfer from wild birds to poultry is used to underpin the assessment of the biosecurity measures described in Decision 2005/734/EC: preventing direct and indirect contact between wild birds and poultry, ensuring separation between domestic ducks and geese from other poultry species and undertaking health checks in poultry flocks. In addition, an overview is provided on the main biosecurity measures applicable in a commercial poultry holding to reduce the risk of AI entry. It was considered that a holding consists of three zones: an open zone (e.g. residence, office), a professional zone (e.g. feed storage) and a production zone (e.g. animal facilities). A ranking of biosecurity measures is done per zone, taking into account feasibility, expected effectiveness and sustainable implementation. This information could be useful when providing guidance to commercial poultry holdings. A preliminary analysis on which measures could be applied in backyard holdings is also provided. However, a more detailed analysis and further practical guidance will be provided later in the scientific opinion. Similarities and differences in phenotypic characteristics of the circulating HPAI H5N8 and HPAI H5N1 are also used to evaluate the implementation of protection measures: the establishment of control monitoring areas after HPAI H5N1 findings in wild birds (Decision 2006/563/EC), establishment of zones A and B after HPAI H5N1 findings in poultry (Decision 2006/415/EC) and the measures and prohibitions to be applied in these areas (both Decisions). Guidance is provided on which epidemiological data are necessary to analyse outbreaks. The derogations of these Decisions are not analysed, except the option to reduce the size of the control and monitoring zone (Article 4 of Decision 2006/563/EC). Finally, the risk of the HPAI H5N8 to humans is briefly described based on the ECDC's recent rapid risk assessment and the outcome of the FLURISK model using the available data. Reference is also made to guidance documents describing protective clothing and prophylactic treatments. 2 Data and methodologies 2.1 Data on the current HPAI H5N8 outbreaks in Europe Data on the AI findings in wild birds, captive birds and poultry were extracted from ADNS for the period 1 October 2016 till 11 December 2016. The affected countries were asked to provide additional information on the infected wild bird species, holding characteristics and detection route. The timing of submission differed among countries: last update on 30/11/2016 (Denmark), 1/12/2016 (Austria, Germany), 2/12/2016 (Croatia, Italy, the Netherlands, Sweden and Switzerland), 5/12/2016 (Finland, Hungary), 7/12/2016 (Poland) and 12/12/2016 (France). The majority of the data have been cross-referenced, but errors cannot be completely excluded given the short time period in which to generate this document. 2.2 Identification and ranking of biosecurity measures A search has been done to identify additional biosecurity measures to those described in Decision 2005/734/EC (see Section A.4 of Appendix A), that could be applied on a commercial poultry holding located in a region where HPAI virus has been detected in poultry and/or wild birds. This means that AI virus exposure to the holding is assumed and hence increased implementation of biosecurity measures is required. Biosecurity guidance documents from several Member States and international organisations like OIE have been screened. Measures have been selected to cover the most important aspects of biosecurity and keeping their number limited to allow an effective and realistic implementation. Each measure is briefly described to achieve a common understanding and to prevent overlap between the measures. Three biosecurity experts also ranked the measures for feasibility, sustainable implementation, effectiveness to prevent entry and effectiveness to prevent spread. For each parameter, the measures were ranked from highest to lowest importance within a given zone of the holding. Feasibility: proportion of the farmers willing to start implementing the given biosecurity measure. Sustainable implementation: proportion of time when the farmer maintains the given biosecurity measure continuously during 30 days of high risk. Effectiveness to reduce entry: reduction in the amount of virus coming from outside to the holding, able to reach poultry within the holding and to cause infection by implementing the given biosecurity measure. Effectiveness to reduce spread: reduction in the amount of virus that can be transferred between poultry within the holding and be released outside of the holding by implementing the given biosecurity measure. The average of the individual rankings was calculated for each of the four parameters. Then, an overall average score was calculated. The measures are described per zone and they are ranked from high to low overall score (see Sections 3.5.2.1 and 3.5.2.3). 3 Assessment 3.1 Overview of the AI outbreaks in Europe during October and November 2016 Figure 1Open in figure viewerPowerPoint Overview of the reported HPAI H5N8 avian influenza cases in Europe between 20 October 2016 and 11 December 2016 HPAI H5N8 in poultry Overall, 163 poultry farms have been found to be infected by the currently circulating HPAI H5N8 virus by 11 December 2016 (Figure 1). The first confirmed case (3/11/2016) was a turkey holding in Hungary. One week later, infected holdings were also reported from Austria, Germany and additional farms in Hungary. The geographic extension of positive poultry holdings continued with confirmed cases in other Member States: Denmark (21/11/2016), the Netherlands (26/11/2016), Sweden (28/11/2016), France (1/12/2016) and Poland (3/12/2016). Several secondary outbreaks are reported in Hungary (106 out of 131 outbreaks) and France (5 out of 11 outbreaks). The number of affected duck farms was 81, of which 70 were in Hungary and 9 in France, whereas 40 outbreaks have been recorded in geese (of which 39 in Hungary), 4 in turkeys, 2 in laying hens, 1 in breeding chickens, 1 in broiler chickens, 1 in chicken (without specification), 1 in guinea fowl, and 18 in multiple or mixed species holdings. There is no species information from 13 holdings. Fifty-one holdings are reported by the Member State as commercial, 15 as backyard holdings (of which 10 are located in Germany) and no information is available on 97 holdings. From these data it seems that domestic waterfowl are at higher risk of contracting the infection than gallinaceous poultry species, however, to estimate the relative risk necessary information on the number of poultry farms holding these species is presently not available. HPAI H5N8 in wild birds The first HPAI H5N8 infected wild bird was reported (27/10/2016) in Hungary, around 1 week before the first outbreak in a poultry holding in this country. A second HPAIV H5N8 infected wild bird was found in Poland on 12/11/2016. The next week, positive cases were reported by five additional Member States (Austria, Croatia, Denmark, Germany and the Netherlands) and Switzerland. Since then, HPAIV H5N8 infected wild birds have also been reported by Sweden, Romania, Finland, France and Serbia. Figure 1 represents the 593 cases reported until 11/12/2016. The numbers cannot be compared between countries and between regions within a country because the surveillance procedures and sensitivity are likely different. Furthermore, the reported numbers do not reflect the real numbers of wild birds that died because of HPAIV H5N8 but likely only a fraction thereof. Several mass mortality events involving 50 or more wild birds at specific locations have been reported, such as in Germany (e.g. Great Plön lake), Switzerland (Lake Constance), Poland (Zachodnio-Pomorskie) and the Netherlands (Gouwzee). During active surveillance, H5N8 was also found in the faeces of a wigeon in Friesland in the Netherlands (R. Fouchier, personal communication, 6 December 2016). Table 1 provides a list of HPAIV infected wild birds reported in ADNS or directly by Member States. Table 1. List of wild and captured birds infected by HPAIV H5N8 in 2014-2015 and/or 2016 (reported by Member States or from other sources) (until 11/12/2016) Wild birds reported by MSs 2014–2015 2016 Black-headed gull (Chroicocephalus ridibundus) X X Common buzzard (Buteo buteo) X Common coot (Fulica atra) X Common eider (Somateria mollissima) X Common goldeneye (Bucephala clangula) X Common gull (Latus canus) X Common magpie (Pica pica) X Common moorhen (Gallinula chloropus) X Common pochard (Aythya ferina) X Carrion crow (Corvus corone) X Eurasian curlew (Numenius arquata) X Eurasian teal (Anas crecca) X X Eurasian wigeon (Anas penelope) X X Great black-backed gull (Larus marinus) X Great crested grebe (Podiceps cristatus) X Great cormorant (Phalacrocorax carbo) X Green sandpiper (Tringa ochropus) X Grey heron (Ardea cinerea) X Herring gull (Larus argentatus) X Hooded crow (Corvus cornix) X Lesser black-backed gull (Larus fuscus) X Little grebe (Tachybaptus ruficollis) X Mallard (Anas platyrhynchos) X X Merganser (Mergus sp.) X Mute swan (Cygnus olor) X Peregrine falcon (Falco peregrinus) X Rails (Rallidae) X Red-crested pochard (Netta rufina) X Shelduck (Tadorna tadorna) X Swans (Cygnus spp.) X X Tufted duck (Aythya fuligula) X White-tailed eagle (Haliaeetus albicilla) X Whooper swan (Cygnus cygnus) X Wild ducks X Wild goose X HPAI H5N8 in captive birds HPAI H5N8 outbreaks have been reported in captive birds on eight different locations (4 in Germany, 2 in the Netherlands, 1 in France and 1 in Finland). Table 2 gives an overview of the affected captive bird species reported so far. Table 2. List of captive birds infected by HPAIV H5N8 in 2014–2015 and/or 2016 (reported by Member States) (until 11/12/2016) Captive birds reported by MSs: 2014–2015 2016 Gadwall (Anas strepera) X Eurasian wigeon (Anas penelope) X X Emu (Dromaius novaehollandiae) X Great white pelican (Pelecanus onocrotalus) X Concurrent LPAI outbreaks in poultry and cases in wild birds In addition to the HPAI H5N8 outbreaks, 10 low pathogenic avian influenza (LPAI) outbreaks have been confirmed since mid-October. Two of these LPAI outbreaks involved captive birds (H7N3 on 18/10/2016 and H5N2 on 18/11/2016, both in Germany). The other eight LPAI outbreaks were in poultry holdings: LPAI H5N2 on a turkey fattening holding in the Netherlands (27/10/2016), LPAI H5N1 and LPAI H5N3 in mixed species holdings in Italy (23/11 and 28/11/2016), five LPAI H5Ny outbreaks in German holdings. The concurrent detection of non-HPAI H5 viruses in wild birds, captive birds and poultry while HPAI H5N8 is spreading in the same populations complicates situation assessment and decision-making regarding the implementation of appropriate restriction measures. Determination of the NA subtype (N8) does not necessarily help as also LPAIVs of subtype H5N8 are in circulation in wild bird populations or have been detected in poultry in France recently. In addition, the presence of concurrent or existing LPAIV infection may confuse the clinical picture of an HPAIV infection. 3.2 Characterisation of the HPAI H5N8 viruses currently circulating in Europe 3.2.1 Genotypic characterisation Phylogenetic analysis European HPAI H5N8 viruses from 2014 and 2016 are genetically distinguishable and are assigned to separate different phylogenetic clusters within the Gs/Gd lineage H5 clade 2.3.4.4. These clusters are derived from evolutionary analyses of the haemagglutinin (HA) gene sequences obtained from positive birds and uploaded to online repositories. In particular, phylogenetic analyses assign the 2016 viruses to clade 2.3.4.4 (Gochang1-like) while the 2014 viruses belonged to clade 2.3.4.4 (Buan2-like) (Lee et al., 2014). Initial analyses of the HA gene generated from samples in the HPAI H5N82016 outbreak suggest the European viruses form two very closely related clusters that segregate by geographical origin; Northern Europe (Denmark, Germany, the Netherlands, Poland and Sweden) and Central Europe (Croatia and Hungary) possibly reflecting different introduction pathways via wild birds and separate circulation pools. The phylogenetic distance between the 2016 Northern Europe and Central Europe clusters is sufficiently close to suggest that these are similar viruses of a common ancestor that have reached Europe via different geographical routes, while the 2014 and 2016 cluster differences on the HA gene suggest enough variation to possibly account for distinct phenotypic changes. HPAI H5N8 viruses found in wild birds in June 2016 at Lake Uvs-Nur at the Russian-Mongolian border constitute the closest (but different) related sequences of the European viruses (Lee et al., 2017). Full genome sequences will be required to further elucidate spread pathways and possible genetic mixing with other AI viruses. No adaptive mutations suggestive of increased risk for transmissibility to humans Available HPAIV H5N8 2016 sequencing data (novel and GISAID) were matched with the CDC (Atlanta) H5N1 genetic changes inventory and the list of mutations required for H5N1 respiratory droplet transmission in ferrets (Herfst et al., 2012; Imai et al., 2012) to identify genetic mutations that determine viral phenotypic characteristics that may signal adaptation to mammalian species or alter susceptibility to existing antivirals. This totals 118 mutations or combinations of mutations. A total of eight mutations/mutation combinations were observed, plus mixed motifs at three additional locations, in the H5N8 2016 viruses (EURL analysis). None of these mutations in isolation are considered to increase the zoonotic affinity of the virus which is still essentially an avian virus (ECDC, 2016). On the contrary, the absence of a deletion in the NS1 at amino acid position 80–84 that is conserved among contemporary H5 viruses might decrease the zoonotic potential of the H5N8 virus. 3.2.2 Phenotypic characterisation Morbidity and mortality in poultry and wild birds Clinical disease was reported in all infected poultry species, in most cases associated with high morbidity and high case fatality in birds. It should be noted that morbidity and mortality rates reported will depend on the time point following incursion when disease was detected and diagnosis confirmed. Thus, it is difficult to compare them between outbreaks. The currently circulating HPAIV H5N8 2016 invokes full presentation as HPAI in chickens as demonstrated by intravenous pathogenicity indices3 (IVPI) close to 3.0 while the 2014/2015 viruses displayed IVPIs of about 2.5–2.8 although no direct comparisons using the same inoculation dose have been performed (EURL – Flulabnet). For domestic ducks, the virulence of the contemporary European HPAI H5N8 appears higher than for viruses that were detected worldwide of clade 2.3.4.4 in 2014/2015. This is based on the apparent high mortality rate of domestic ducks reported from farms in southwestern France, in the Netherlands and in Hungary in 2016, compared to the low mortality rate of domestic ducks in farms in the UK, Germany and the Netherlands which resulted from HPAI H5N8 viruses in 2014. However, it should be noted that cases of secondary infection are being reported in the absence of overt clinical disease. Experimental infection studies in domestic (Pekin) ducks are expected to give further insights into the virulence of clade 2.3.4.4/2016 viruses for anseriforme species. Passive monitoring in wild birds recorded excess and regionally even mass mortality in several diving duck species (tufted duck, common pochard and greater scaup). Gross pathology of carcasses of these birds revealed evidence of systemic infection with macroscopic lesions dominating in lung and liver tissues. Viral shedding at high titres from both oropharyngeal and cloacal excretions of these birds has been confirmed. Lethal courses of infection were also seen in other species of anseriform wild birds. These include mute swans, larger geese species (Canada, Greylag and Bean geese). Very few cases of infected dabbling ducks were recorded so far although large numbers of European wigeons in the Netherlands tested positive recently. In addition, grebes and gull species were sporadically affected (black-headed gull, herring gull, lesser black-backed gull and greater black-Backed Gull) and also birds of prey, mainly common buzzard but also white-tailed eagle. Longitudinally, there seemed to be a shift in the species range after the incursion of 2016 HP H5N8 into wild birds in Central Europe: diving ducks were first to be seen affected, later the infection spread to swans, geese and species of grebes and finally ended up in scavenging predator species such as herring gulls, carrion crows, common buzzards and white-tailed eagles. For wild birds, the virulence of HPAIV H5N8 2016 appeared to be higher compared to HPAI H5N8 2014/2015. This is based, i.e., on the detection of H5N8 virus in faecal samples of apparently healthy Eurasian wigeons in the Netherlands in 2014/2015 in the absence of any observed mortality of Eurasian wigeons, compare
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