Avian influenza overview May - August 2020

Transmission dynamics and pathogenesis differ between pheasants and partridges infected with clade 2.3.4.4b H5N8 and H5N1 high-pathogenicity avian influenza viruses

During the UK 2020-2021 epizootic of H5Nx clade 2.3.4.4b high-pathogenicity avian influenza viruses (HPAIVs), high mortality occurred during incursions in commercially farmed common pheasants (Phasianus colchicus). Two pheasant farms, affected separately by H5N8 and H5N1 subtypes, included adjacently housed red-legged partridges (Alectoris rufa), which appeared to be unaffected. Despite extensive ongoing epizootics, H5Nx HPAIV partridge outbreaks were not reported during 2020-2021 and 2021-2022 in the UK, so it is postulated that partridges are more resistant to HPAIV infection than other gamebirds. To assess this, pathogenesis and both intra- and inter-species transmission of UK pheasant-origin H5N8-2021 and H5N1-2021 HPAIVs were investigated. Onward transmission to chickens was also assessed to better understand the risk of spread from gamebirds to other commercial poultry sectors. A lower infectious dose was required to infect pheasants with H5N8-2021 compared to H5N1-2021. However, HPAIV systemic dissemination to multiple organs within pheasants was more rapid following infection with H5N1-2021 than H5N8-2021, with the former attaining generally higher viral RNA levels in tissues. Intraspecies transmission to contact pheasants was successful for both viruses and associated with viral environmental contamination, while interspecies transmission to a first chicken-contact group was also efficient. However, further onward transmission to additional chicken contacts was only achieved with H5N1-2021. Intra-partridge transmission was only successful when high-dose H5N1-2021 was administered, while partridges inoculated with H5N8-2021 failed to shed and transmit, although extensive tissue tropism was observed for both viruses. Mortalities among infected partridges featured a longer incubation period compared to that in pheasants, for both viruses. Therefore, the susceptibility of different gamebird species and pathogenicity outcomes to the ongoing H5Nx clade 2.3.4.4b HPAIVs varies, but pheasants represent a greater likelihood of H5Nx HPAIV introduction into galliforme poultry settings. Consequently, viral maintenance within gamebird populations and risks to poultry species warrant enhanced investigation.

An early warning system for highly pathogenic viruses borne by waterbird species and related dynamics of climate change in the Caspian Sea region: Outlines of a concept

Aim. Formulation of the outlines of the concept of ViEW (Viral Early Warning) which is intended as a long term system of multidisciplinary transboundary cooperation between specialist institutions of all five Caspian region states to research, regularly monitor and share data about the generation, transmission and epidemiology of avian‐borne pathogens and their vectors in the region, and the ways climate change may affect these processes.

Material and Methods. The concept is based on the multidisciplinary experience of the authors in researching the processes incorporated in the ViEW concept and on an in‐depth survey of the literature involved.

Results. The outlines of the ViEW concept are presented in this study for review and comment by interested parties and stakeholders.

Conclusion. Review of activities and opinions of specialists and organizations with remits relating to the development, establishment and maintenance of ViEW, indicates that such a system is a necessity for global animal and human health because of the role that the Caspian region plays in the mass migration of species of waterbird known as vectors for avian influenza and the already evident impacts of climate change on their phenologies. Waterbirds frequenting the Caspian Sea littorals and their habitats together constitute a major potential global hotspot or High Risk region for the generation and transmission of highly pathogenic avian influenza viruses and other dangerous zoonotic diseases.

European Food Safety Authority, European Centre for Disease Prevention and Control, European Union Reference Laboratory for Avian Influenza, Adlhoch C, Fusaro A, Gonzales JL, Kuiken T, Marangon S, Niqueux É, Staubach C, Terregino C, Guajardo IM, Chuzhakina K, Baldinelli F. Avian influenza overview June - September 2022

The 2021-2022 highly pathogenic avian influenza (HPAI) epidemic season is the largest HPAI epidemic so far observed in Europe, with a total of 2,467 outbreaks in poultry, 47.7 million birds culled in the affected establishments, 187 outbreaks in captive birds, and 3,573 HPAI virus detections in wild birds with an unprecedent geographical extent reaching from Svalbard islands to South Portugal and Ukraine, affecting 37 European countries. Between 11 June and 9 September 2022, 788 HPAI virus detections were reported in 16 European countries in poultry (56), captive (22) and wild birds (710). Several colony-breeding seabird species exhibited widespread and massive mortality from HPAI A(H5N1) virus along the northwest coast of Europe. This resulted in an unprecedentedly high level of HPAI virus detections in wild birds between June and August 2022 and represents an ongoing risk of infection for domestic birds. HPAI outbreaks were still observed in poultry from June to September with five-fold more infected premises than observed during the same period in 2021 and mostly distributed along the Atlantic coast. Response options to this new epidemiological situation include the definition and rapid implementation of suitable and sustainable HPAI mitigation strategies such as appropriate biosecurity measures and surveillance strategies for early detection in the different poultry production systems. The viruses currently circulating in Europe belong to clade 2.3.4.4b with seven genotypes, three of which identified for the first time during this time period, being detected during summer. HPAI A(H5) viruses were also detected in wild mammal species in Europe and North America and showed genetic markers of adaptation to replication in mammals. Since the last report, two A(H5N6), two A(H9N2) and one A(H10N3) human infections were reported in China. The risk of infection is assessed as low for the general population in the EU/EEA, and low to medium for occupationally exposed people.

Preparation of a broad-specific monoclonal antibody and development of an immunochromatographic assay for monitoring of anthranilic diamides in vegetables and fruits

A mAb-based lateral flow immunochromatographic strip for the detection of anthranilic diamides in vegetables and fruits was developed. The strip provided cut-off values of 2.5, 5, 10, and 10 ng g−1 for CHL, CYA, CYC, and TEA, respectively.

European Food Safety Authority, European Centre for Disease Prevention and Control, European Union Reference Laboratory for Avian Influenza, Adlhoch C, Fusaro A, Gonzales JL, Kuiken T, Marangon S, Niqueux É, Staubach C, Terregino C, Aznar I, Guajardo IM, Lima E, Baldinelli F. Avian influenza overview February - May 2021

The 2020-2021 epidemic with a total of 3,555 reported HPAI detections and around 22,400,000 affected poultry birds in 28 European Countries appears to be one of the largest and most devastating HPAI epidemics ever occurred in Europe. Between 24 February and 14 May 2021, 1,672 highly pathogenic avian influenza (HPAI) virus detections were reported in 24 EU/EEA countries and the UK in poultry (n=580), and in wild (n=1,051) and captive birds (n=41). The majority of the detections in poultry were reported by Poland that accounted for 297 outbreaks occurring in a densely populated poultry area over a short period of time, followed by Germany with 168 outbreaks. Germany accounted for 603 detections in wild birds, followed by Denmark and Poland with 167 and 56 detections, respectively. A second peak of HPAI-associated wild bird mortality was observed from February to April 2021 in north-west Europe. The observed longer persistence of HPAI in wild birds compared to previous years may result in a continuation of the risk for juveniles of wild birds and mammals, as well as for virus entry into poultry farms. Therefore, enhanced awareness among farmers to continue applying stringent biosecurity measures and to monitor and report increases in daily mortality and drops in production parameters, are recommended. Sixteen different genotypes were identified to date in Europe and Russia, suggesting a high propensity of these viruses to reassort. The viruses characterized to date retain a preference for avian-type receptors; however, transmission events to mammals and the identification of sporadic mutations of mammal adaptation, indicate ongoing evolution processes and possible increased ability of viruses within this clade to further adapt and transmit to mammals including humans. Since the last report, two human infections due to A(H5N6) HPAI were reported from China and Laos and 10 human cases due to A(H9N2) low pathogenic avian influenza (LPAI) virus identified in China and Cambodia. The risk of infection for the general population in the EU/EEA is assessed as very low and for occupationally exposed people low. People exposed during avian influenza outbreaks should adhere to protection measures, strictly wear personal protective equipment and get tested immediately when developing respiratory symptoms or conjunctivitis within 10 days after exposure.

Evolutionary Dynamics of H5 Highly Pathogenic Avian Influenza Viruses (Clade 2.3.4.4B) Circulating in Bulgaria in 2019-2021

The first detection of a Highly Pathogenic Avian Influenza (HPAI) H5N8 virus in Bulgaria dates back to December 2016. Since then, many outbreaks caused by HPAI H5 viruses from clade 2.3.4.4B have been reported in both domestic and wild birds in different regions of the country. In this study, we characterized the complete genome of sixteen H5 viruses collected in Bulgaria between 2019 and 2021. Phylogenetic analyses revealed a persistent circulation of the H5N8 strain for four consecutive years (December 2016-June 2020) and the emergence in 2020 of a novel reassortant H5N2 subtype, likely in a duck farm. Estimation of the time to the most recent common ancestor indicates that this reassortment event may have occurred between May 2019 and January 2020. At the beginning of 2021, Bulgaria experienced a new virus introduction in the poultry sector, namely a HPAI H5N8 that had been circulating in Europe since October 2020. The periodical identification in domestic birds of H5 viruses related to the 2016 epidemic as well as a reassortant strain might indicate undetected circulation of the virus in resident wild birds or in the poultry sector. To avoid the concealed circulation and evolution of viruses, and the risk of emergence of strains with pandemic potential, the implementation of control measures is of utmost importance, particularly in duck farms where birds display no clinical signs.

Pathogenicity of H5N8 High Pathogenicity Avian Influenza Virus in Chickens and Ducks from South Korea in 2020-2021

During the 2020–2021 winter season, an outbreak of clade 2.3.4.4b H5N8 high pathogenicity avian influenza (HPAI) virus occurred in South Korea. Here, we evaluated the pathogenicity and transmissibility of A/mandarin duck/Korea/H242/2020 (H5N8) (H242/20(H5N8)) first isolated from this outbreak in specific pathogen-free (SPF) chickens and commercial ducks in comparison with those of A/duck/Korea/HD1/2017(H5N6) (HD1/17(H5N6)) from a previous HPAI outbreak in 2017–2018. In chickens, the 50% chicken lethal dose and mean death time of H242/20(H5N8) group were 10^4.5 EID₅₀ and 4.3 days, respectively, which indicate less virulent than those of HD1/17(H5N6) (10^3.6 EID₅₀ and 2.2 days). Whereas, chickens inoculated with H242/20(H5N8) survived longer and had a higher titer of viral shedding than those inoculated with HD1/17(H5N6), which may increase the risk of viral contamination on farms. All ducks infected with either HPAI virus survived without clinical symptoms. In addition, they exhibited a longer virus shedding period and a higher transmission rate, indicating that ducks may play an important role as a silent carrier of both HPAI viruses. These results suggest that the pathogenic characteristics of HPAI viruses in chickens and ducks need to be considered to effectively control HPAI outbreaks in the field.

Molecular Characterization of Highly Pathogenic Avian Influenza Viruses H5N6 Detected in Denmark in 2018-2019

Beginning in late 2017, highly pathogenic avian influenza (HPAI) H5N6 viruses caused outbreaks in wild birds and poultry in several European countries. H5N6 viruses were detected in 43 wild birds found dead throughout Denmark. Most of the Danish virus-positive dead birds were found in the period from February to April 2018. However, unlike the rest of Europe, sporadic HPAI H5N6-positive dead wild birds were detected in Denmark in July, August, September, and December 2018, with the last positive bird being found in January 2019. HPAI viruses were not detected in active surveillance of apparently healthy wild birds. In this study, we use full genome sequencing and phylogenetic analysis to investigate the wild bird HPAI H5N6 viruses found in Denmark. The Danish viruses were found to be closely related to those of contemporary HPAI H5N6 viruses detected in Europe. Their sequences formed two clusters indicating that at least two or more introductions of H5N6 into Denmark occurred. Notably, all viruses detected in the latter half of 2018 and in 2019 grouped into the same cluster. The H5N6 viruses appeared to have been maintained undetected in the autumn 2018.

European Food Safety Authority, European Centre for Disease Prevention and Control and European Union Reference Laboratory for Avian Influenza, Adlhoch C, Fusaro A, Gonzales JL, Kuiken T, Marangon S, Niqueux É, Staubach C, Terregino C, Muñoz Guajardo I, Lima E, Baldinelli F. Avian influenza overview December 2020 - February 2021

Between 8 December 2020 and 23 February 2021, 1,022 highly pathogenic avian influenza (HPAI) virus detectionswere reported in 25 EU/EEA countries and the UK in poultry (n=592), wild (n=421) and captive birds (n=9).The majority of the detections were reported by Francethat accounted for 442 outbreaks in poultry,mostly located inthe Landes regionandaffecting the foie gras production industry,and six wild bird detections; Germany,who reported 207 detections in wild birds and 50 poultry outbreaks; Denmark,with 63 detections in wild birds and one poultry outbreak; and Poland,with 37 poultry outbreaks and 24 wild bird detections. Due to the continued presence of HPAI A(H5) viruses in wild birds and the environment,there is still a risk of avian influenza incursions with the potential further spread between establishments, primarily in areas with high poultry densities. As the currently circulating HPAI A(H5N8) virus cancause high mortality also in affected duck farms, mortality eventscan be seen as a good indicator of virus presence. However,also subclinical virusspread in this type of poultry production system have been reported.To improve early detection of infection in poultry within the surveillance zone, the clinical inspection of duck establishments should be complemented by encouraging farmers to collect dead birds to be pooled and tested weekly (bucket sampling).Six different genotypes were identified to date in Europe and Russia, suggesting a high propensity of these viruses to undergo multiple reassortment events. To date, no evidence of fixation of known mutations previously described as associated to zoonotic potential has been observed in HPAI viruses currently circulanting in Europe based on the available sequences.Seven cases due to A(H5N8) HPAI virus have been reported from Russia, all were poultry workerswith mild or no symptoms. Five human cases due to A(H5N6) HPAI and 10 cases due to A(H9N2) LPAI viruseshave been reported from China. The risk for the general population as well as travel-related imported human cases is assessed as very lowand the risk forpeople occupationally exposedpeople as low.Any human infections with avian influenza viruses are notifiablewithin 24 hoursthrough the Early Warning and Response System (EWRS) and the International Health Regulations (IHR) notification system.

EFSA Panel on Animal Health and Welfare (EFSA AHAW Panel), Nielsen SS, Alvarez J, Bicout DJ, Calistri P, Depner K, Drewe JA, Garin‐Bastuji B, Gonzales Rojas JL, Schmidt CG, Herskin M, Michel V, Miranda Chueca MÁ, Pasquali P, Roberts HC, Sihvonen LH, Spoolder H, Stahl K, Calvo AV, Viltrop A, Winckler C, De Clercq K, Klement E, Stegeman JA, Gubbins S, Antoniou S, Broglia A, Van der Stede Y, Zancanaro G, Aznar I. Scientific Opinion on the assessment of the control measures of the category A diseases of Animal Health Law: Highly Pathogenic Avian Influenza

EFSA received a mandate from the European Commission to assess the effectiveness of some of the control measures against diseases included in the Category A list according to Regulation (EU) 2016/429 on transmissible animal diseases ('Animal Health Law'). This opinion belongs to a series of opinions where these control measures will be assessed, with this opinion covering the assessment of control measures for Highly Pathogenic Avian Influenza (HPAI). In this opinion, EFSA and the AHAW Panel of experts review the effectiveness of: (i) clinical and laboratory sampling procedures, (ii) monitoring period and (iii) the minimum radius of the protection and surveillance zone, and the minimum length of time the measures should be applied in these zones. The general methodology used for this series of opinions has been published elsewhere; nonetheless, specific details of the model used for the assessment of the laboratory sampling procedures for HPAI are presented here. Here, also, the transmission kernels used for the assessment of the minimum radius of the protection and surveillance zones are shown. Several scenarios for which these control measures had to be assessed were designed and agreed prior to the start of the assessment. In summary, sampling procedures as described in the diagnostic manual for HPAI were considered efficient for gallinaceous poultry, whereas additional sampling is advised for Anseriformes. The monitoring period was assessed as effective, and it was demonstrated that the surveillance zone comprises 95% of the infections from an affected establishment. Recommendations provided for each of the scenarios assessed aim to support the European Commission in the drafting of further pieces of legislation, as well as for plausible ad hoc requests in relation to HPAI.

Avian influenza overview August - December 2020

Between 15 August and 7 December 2020, 561highly pathogenic avian influenza (HPAI) virus detections were reported in 15EU/EEA countries and UK in wild birds, poultry andcaptive birds, with Germany (n=370), Denmark (n=65), the Netherlands (n=57) being the most affected countries.The majority of the detections have been reported in wild birds(n=510), primarily in barnacle goose, greylag goose, andEurasian wigeon. Raptors have also been detected infected, particularly common buzzard. The majority of the birds had been found dead or moribund,however, there are also reports ofHPAI virus infection in apparently healthy ducks or geese.A total of 43 HPAI outbreaks were notified in poultry;with signs of avian influenza infection being observed in at least 33 outbreaks;the most likely source of infection was indirect contact with wild birds. Three HPAI virus subtypes, A(H5N8) (n=518), A(H5N5) (n=17) and A(H5N1) (n=6),and four different genotypes were identified, suggesting the occurrence of multiple virus introductions into Europe.The reassortant A(H5N1) virus identified in EU/EEA countries has acquired gene segments from low pathogenic viruses and is not related to A(H5N1) viruses of e.g. clade 2.3.2.1c causing human infections outside of Europe. As the autumn migration of wild waterbirds to their wintering areasin Europe continues, and given the expected local movements of these birds, there is still a high risk of introduction andfurther spread ofHPAI A(H5) viruses within Europe.The risk of virus spread from wild birds to poultry is high and Member States should enforce in 'high risk areas' of their territories the measures provided for in Commission Implementing Decision (EU) 2018/1136.Detection of outbreaks in breeder farms in Denmark, the Netherlands and United Kingdom, highlight also the risk of introduction via contaminated materials (bedding/straw) and equipment.Maintaining high and sustainable surveillance and biosecurityparticularly in high-risk areas is of utmost importance. Two human cases due to zoonoticA(H5N1) and A(H9N2) avian influenza virus infection were reportedduring the reporting period. The risk for the general population as well as travel-related imported human cases are assessed as very low.

European Food Safety Authority, European Centre for Disease Prevention Control and European Union Reference Laboratory for Avian Influenza, Adlhoch C, Fusaro A, Gonzales JL, Kuiken T, Marangon S, Niqueux É, Staubach C, Smietanka K, Terregino C, Van der Stede Y, Aznar I, Baldinelli F. Avian influenza overview - update on 19 November 2020, EU/EEA and the UK

Since 16 October 2020, outbreaks ofhighly pathogenic avian influenza (HPAI) viruseshavebeen reported inseveral EU/EEAcountries -Belgium, Denmark, France, Germany, Ireland, the Netherlands, and Swedenas well asin the United Kingdom.As of 19 November,12pm, 302 HPAI A(H5) detections have been reported, with the majority of the detections referring to wild birds (n=281), and a few related to outbreaks in poultry (n=18) and captive birds (n=3). Most of the detections in wild birds were in wild waterbirds,being barnacle goose the most affected species (n=110), followed by greylag goose (n=47), Eurasian wigeon (n=32),mallard (n=14), and common buzzard (n=13).ThreeHPAI virus subtypes were identified, A(H5N8), A(H5N5) and A(H5N1), with A(H5N8) being the most reported subtype (n=284). Phylogenetic analysis indicated that the viruses evolved from a single progenitor virus thatwent through multiple reassortment events. Based on the ongoing autumn migration of wild waterbirds to their wintering areas in Europe, there is a continued risk of further introduction of HPAI A(H5) viruses into Europe. Furthermore, given the expected movements of both migratory, and resident wild birds in Europe during winter, there is a high risk of further spread of HPAI A(H5) viruses within Europe. No genetic markers indicating adaptation to mammals have been identified in the viruses analysed so far,andno human infection due to avian influenza viruses detected in the recent outbreakshas been reported. For that reason,the risk to the general population remains very low.However,following the precautionary principle, people should avoid touching sick or dead birds unprotected to minimise any potential risk.