On 6 June 2017, the World Health Organization (WHO) published updates to its ‘Essential Medicines List’ (EML). Read more here.

Extended deadline (from 1 July to 31 July) 2017 for call to submit papers on effectiveness and cost-effectiveness of screening and prevention of infectious diseases among newly arrived migrants in Europe. Read more here.

Eurosurveillance is on the updated list of the Directory of Open Access Journals and in the SHERPA/RoMEO database. Read more here.

Follow Eurosurveillance on Twitter: @Eurosurveillanc

In this issue

Home Eurosurveillance Edition  2014: Volume 19/ Issue 50 Article 1
Back to Table of Contents
Download (pdf)

Eurosurveillance, Volume 19, Issue 50, 18 December 2014
Rapid communications
Comparing introduction to Europe of highly pathogenic avian influenza viruses A(H5N8) in 2014 and A(H5N1) in 2005
  1. European Centre for Disease Prevention and Control (ECDC), Stockholm, Sweden
  2. School of Public Health and Primary Care, Maastricht University Medical Center, Maastricht, The Netherlands
  3. Central Veterinary Institute of Wageningen University and Research Centre, Lelystad, The Netherlands
  4. Animal and Plant Health Agency-Weybridge, Addlestone, Surrey, United Kingdom
  5. European Food Safety Authority (EFSA), Parma, Italy
  6. Friedrich-Loeffler-Institute (FLI), Federal Research Institute for Animal Health, Greifswald – Insel Riems, Germany

Citation style for this article: Adlhoch C, Gossner C, Koch G, Brown I, Bouwstra R, Verdonck F, Penttinen P, Harder T. Comparing introduction to Europe of highly pathogenic avian influenza viruses A(H5N8) in 2014 and A(H5N1) in 2005. Euro Surveill. 2014;19(50):pii=20996. Article DOI:
Date of submission: 15 December 2014

Since the beginning of November 2014, nine outbreaks of highly pathogenic avian influenza virus (HPAIV) A(H5N8) in poultry have been detected in four European countries. In this report, similarities and differences between the modes of introduction of HPAIV A(H5N1) and A(H5N8) into Europe are described. Experiences from outbreaks of A(H5N1) in Europe demonstrated that early detection to control HPAIV in poultry has proven pivotal to minimise the risk of zoonotic transmission and prevention of human cases.
Highly pathogenic avian influenza virus A(H5N1) and A(H5N8) outbreaks in domestic poultry and wild birds in Europe

Outbreaks of highly pathogenic avian influenza virus (HPAIV) A(H5N8) in domestic poultry and wild birds in Europe in 2014 have some similarities to the previous introduction of HPAIV A(H5N1). Since beginning of November 2014, nine outbreaks have been detected in four countries in Europe. Comparisons between these incursions may help to better understand potential risks to public health.

In autumn 2005, Romania and Croatia were the first European countries reporting influenza A(H5N1) virus infections in wild birds and domestic poultry; hereafter, it spread rapidly across central Europe starting in February 2006 [1]. When HPAIV A(H5N1) finally disappeared in 2010, it had been detected in wild birds and poultry in 21 European countries (Table) [2]. Prior to the introduction into Europe, HPAIV A(H5N1) was extensively circulating in poultry, with recurrent spill-overs to wild birds, in Asia [3].

Table. European countries with reported outbreaks of influenza A(H5N1) and influenza A(H5N8) virus infection in domestic poultry and wild birds, 2003 to 2014a

Influenza A(H5N8) virus is a complex reassortant virus carrying genes from A(H5N1) as one of its parental viruses. An ancestral strain was first reported in China in 2010 [4]. In 2014, following further virus evolution via reassortment, several outbreaks with HPAIV A(H5N8) viruses occurred in aquatic migratory birds, chickens, geese and ducks in China, Japan, and Republic of Korea [2,5-10]. Between 5 November and 16 December 2014, Germany, Italy, the Netherlands, and the United Kingdom (UK) reported HPAIV A(H5N8) outbreaks in nine holdings in total, with turkeys, chickens or ducks [11] (Figure, Table).

Figure. Countries reporting outbreaks of influenza A(H5N8) virus infection in domestic poultry and wild birds, 2014

In November and December 2014, HPAIV A(H5N8) was detected in a healthy common teal (Anas crecca) in Germany and in two faecal samples from Eurasian wigeons (Anas penelope) in the Netherlands. The region in Germany currently affected by HPAIV A(H5N8) largely matches the area that was first affected by HPAIV A(H5N1), whereas in the UK, cases of A(H5N1) were initially located in eastern and southern regions and in Italy in central and southern regions, but not in the areas affected in November 2014. The Netherlands had not been affected by HPAIV A(H5N1) at all [12].

Influenza A(H5N8) virus infection does not appear to be associated with severe illness or excessive mortality in wild mallard ducks [10]. In contrast, in galliform poultry (turkey, chickens), HPAIV A(H5N8) causes mass mortality as seen in affected holdings [2]. The low to moderate virulence of HPAIV A(H5N8) in domestic ducks seen in the UK resembles the situation in wild mallards [2]. Many strains of HPAIV A(H5N1), in contrast, cause high mortality not only in galliformes but also in anseriform poultry and in wild birds [13,14].

Routes of introduction into Europe

The spread of HPAIV A(H5N1) from east Asia to Europe via central Asia may have occurred by a complex mixture of activities associated with poultry production, illegal poultry transports, spill-over infections to wild birds, and migratory bird dispersal, but no consistent route of infection into poultry holdings within Europe has been identified [15]. The sudden occurrence of HPAIV A(H5N1) in central Europe in 2006 was probably associated with cold spells in western Russia that drove out substantial numbers of putatively infected wild birds further west [16]. 

Mutual transmission of HPAIV between migratory birds and domestic poultry might occur through direct or indirect contacts [7]. Genetic analyses of the recent European influenza A(H5N8) viruses revealed very high similarity to Japanese wild bird isolates suggesting a common source of infection [17].

Import of live poultry and live captive birds as well as poultry commodities from affected Asian regions to the European Union (EU) is illegal but cannot be formally excluded as route of introduction for HPAIV A(H5N8); however, this seems unlikely considering the simultaneous nature and geographic spread of the outbreaks. No epidemiological links have been identified between the initially affected holdings in Germany, the Netherlands and the UK. Findings of HPAIV A(H5N8) in wild birds in Europe also open a possibility for an importation from Asia to Europe via migratory wild birds although this remains hypothetical until the virus would be found in further wild bird populations in central and western Asia.

Affected holdings in Europe so far were indoor facilities with nominally good biosecurity, yet indirect contact between wild birds and poultry (via any material contaminated by infected wild birds, e.g. faeces) might be possible. The fact that in several of the holdings, stable units closest to the entrance of the compound were the first affected in the outbreak, might suggest the introduction of A(H5N8) from a focal source close to the compound.

Surveillance of highly pathogenic avian influenza viruses in the European Union

The experience of large HPAIV outbreaks of in the Netherlands, Belgium and Germany, e.g. A(H7N7) in 2003, prompted the EU to better prepare for large scale incursions of HPAIV [18]. The establishment and implementation of surveillance systems, diagnostic tools for early detection of HPAIV and harmonised restriction and control measures was laid down in the EU legislation [19]. This included introducing programmes of passive surveillance of wild bird populations as an early warning system, which proved to be a useful tool in detecting presence of HPAIV A(H5N1). This was complemented by active monitoring of poultry. In the current epizootic, enhanced wild bird monitoring might also help to further elucidate the role of wild birds transmitting A(H5N8), although the apparently asymptomatic presentation in wild bird species in Europe indicates potentially scaling up elements of targeted active rather than passive surveillance may be appropriate to better understand the distribution, prevalence and introduction pathways into Europe.

Risk for human transmission and resulting public health measures

Although to date, HPAIV A(H5N1) has caused 676 human cases worldwide, including 398 deaths [20], no human cases have ever been reported in Europe and these viruses lack the capability for sustained human-to-human transmission. Cats and mustelids were the only mammals found to be infected in Europe [13]. No human cases due to A(H5N8) have so far been reported anywhere. Mammals such as mice, ferrets, dogs and cats proved to be susceptible to experimental A(H5N8) infection, yet, only mild clinical disease, if any, ensued and so their role as amplification or reservoir hosts appears less likely [21].

Binding of avian influenza viruses to mammalian α2–6 sialic acid receptors is a prerequisite for transmission to humans. HPAIV A(H5N8) binds strongly to avian α2–3 receptors and, to a markedly lesser degree, to α2–6 receptors indicating limited zoonotic potential [21]. Antiviral resistance has not been described in the recent isolates [17]. Candidate vaccine viruses for human use have been proposed for pandemic preparedness [22].

People at risk of spill-over infections are those directly exposed to infected birds and their carcasses, e.g. during culling measures in affected holdings. Personal protective equipment and other protective measures are a prerequisite for preventing zoonotic transmission. Passive or active monitoring of exposed persons enables early identification of transmission events. There is no evidence of human infection through consumption of contaminated food [23]. Recommended diagnostic tests for animal and human samples showed reliable detection of HPAIV A(H5N8).


The current simultaneous occurrence of A(H5N8) in different European countries is comparable to the introduction of A(H5N1) around a decade ago. These similarities may point to common routes of introduction into Europe, although these are not fully understood and the exact sources of infection of the affected indoor poultry holdings have not been identified yet. More outbreaks seem possible. Although HPAIV A(H5N8) might have the potential to transmit to humans, no human cases have been detected so far. Based on the experience from HPAIV A(H5N1) in Europe, efficient biosecurity, early detection, and stringent control measures are able to minimize risks of spill-over transmission to humans. The rapid geographic dispersion of yet another reassortant highly pathogenic avian influenza A virus underlines the need for enhanced preparedness.
The authors are grateful to Kaja Kaasik Aaslav and Silviu Ionescu for creating the map as well as the epidemic intelligence team at ECDC for their support.
This paper is published under the sole responsibility of the authors. The positions and opinions presented are those of the authors alone, and are not intended to represent the views of EFSA.

Authors’ contributions
CA: study initiation, compilation of data, drafting the manuscript
CG: critical review and drafting of the manuscript
GK & RB: data provision from outbreaks in the Netherlands, critical review and approval of the manuscript
IB: providing data from the UK and EUR Lab, critical review and approval of the manuscript
FV: providing EFSA data, critical review and approval of the manuscript
PP: critical review and approval of the manuscript
TH: study concept and providing German data, manuscript draft, critical review and approval

  1. World Organisation for Animal Health (OIE). Avian Influenza. Facts & Figures: H5N1 Timeline. Paris: OIE. [Accessed 4 Dec 2014]. Available from:
  2. World Organisation for Animal Health (OIE). UPDATE ON HIGHLY PATHOGENIC AVIAN INFLUENZA IN ANIMALS (TYPE H5 and H7). Paris: OIE. [Accessed 15 Dec 2014]. Available from:
  3. Brown IH. Summary of avian influenza activity in Europe, Asia, and Africa, 2006-2009. Avian Dis. 2010;54(1 Suppl):187-93.
  4. Gu M, Liu W, Cao Y, Peng D, Wang X, Wan H, et al. Novel reassortant highly pathogenic avian influenza (H5N5) viruses in domestic ducks, China. Emerg Infect Dis. 2011;17(6):1060-3. PMID:21749770
  5. Lee YJ, Kang HM, Lee EK, Song BM, Jeong J, Kwon YK, et al. Novel reassortant influenza A(H5N8) viruses, South Korea, 2014. Emerg Infect Dis. 2014;20(6):1087-9. PMID:24856098
  6. Ku KB, Park EH, Yum J, Kim JA, Oh SK, Seo SH. Highly pathogenic avian influenza A(H5N8) virus from waterfowl, South Korea, 2014. Emerg Infect Dis. 2014;20(9):1587-8. PMID:25152954
  7. Jeong J, Kang HM, Lee EK, Song BM, Kwon YK, Kim HR, et al. Highly pathogenic avian influenza virus (H5N8) in domestic poultry and its relationship with migratory birds in South Korea during 2014. Vet Microbiol. 2014;173(3-4):249-57. PMID:25192767
  8. Wu H, Peng X, Xu L, Jin C, Cheng L, Lu X, et al. Novel reassortant influenza A(H5N8) viruses in domestic ducks, eastern China. Emerg Infect Dis. 2014;20(8):1315-8. PMID:25075453
  9. Fan S, Zhou L, Wu D, Gao X, Pei E, Wang T, et al. A novel highly pathogenic H5N8 avian influenza virus isolated from a wild duck in China. Influenza Other Respir Viruses. 2014;8(6):646-53
  10. Zhao K, Gu M, Zhong L, Duan Z, Zhang Y, Zhu Y, et al. Characterization of three H5N5 and one H5N8 highly pathogenic avian influenza viruses in China. Vet Microbiol. 2013;163(3-4):351-7. PMID:23375651
  11. World Organisation for Animal Health (OIE). Highly pathogenic avian influenza, Germany. Paris: OIE. [Accessed 10 Nov 2014]. Available from:
  12. Si Y, de Boer WF, Gong P. Different environmental drivers of highly pathogenic avian influenza H5N1 outbreaks in poultry and wild birds. PLoS ONE. 2013;8(1):e53362. PMID:23308201
  13. Starick E, Beer M, Hoffmann B, Staubach C, Werner O, Globig A, et al. Phylogenetic analyses of highly pathogenic avian influenza virus isolates from Germany in 2006 and 2007 suggest at least three separate introductions of H5N1 virus. Vet Microbiol. 2008;128(3-4):243-52. PMID:18031958
  14. Chen H, Li Y, Li Z, Shi J, Shinya K, Deng G, et al. Properties and dissemination of H5N1 viruses isolated during an influenza outbreak in migratory waterfowl in western China. J Virol. 2006;80(12):5976-83. PMID:16731936
  15. Gauthier-Clerc M, Lebarbenchon C, Thomas F. Recent expansion of highly pathogenic avian influenza H5N1: a critical review. Ibis. 2007;149(2):202-14.
  16. Reperant LA, Fuckar NS, Osterhaus AD, Dobson AP, Kuiken T. Spatial and temporal association of outbreaks of H5N1 influenza virus infection in wild birds with the 0 degrees C isotherm. PLoS Pathog. 2010;6(4):e1000854. PMID:20386716
  17. European Food Safety Authority (EFSA). Highly pathogenic avian influenza A subtype H5N8 2014 [15 Dec 2014].
  18. Pittman M, Laddomada A. Legislation for the control of avian influenza in the European union. Zoonoses and public health. 2008;55(1):29-36. 
  19. Council of the European Union. Council Directive 2005/94/EC of 20 December 2005 on Community measures for the control of avian influenza and repealing Directive 92/40/EEC. Luxembourg: Official Journal of the European Union. 14 Jan 2006. Available from:
  20. World Health Organization (WHO). Influenza at the human-animal interface. Summary and assessment as of 4 December 2014. Geneva: WHO. [Accessed 15 Dec 2014]. Available from:</eref>
  21. Kim Y-I, Pascua PNQ, Kwon H-I, Lim G-J, Kim E-H, Yoon S-W, et al. Pathobiological features of a novel, highly pathogenic avian influenza A(H5N8) virus. Emerg Microbes & Infect. 22 Oct 2014. doi:10.1038/emi.2014.75
  22. World Health Organization (WHO). Antigenic and genetic characteristics of zoonotic influenza viruses and development of candidate vaccine viruses for pandemic preparedness. Geneva: WHO. [Accessed 17 Nov 2014]. Available from:
  23. European Food Safety Authority (EFSA). Statement on Food safety considerations of novel H1N1 influenza virus infections in humans. EFSA Journal 2010; 8(6):1629. Available from:

Back to Table of Contents
Download (pdf)

The publisher’s policy on data collection and use of cookies.

Disclaimer: The opinions expressed by authors contributing to Eurosurveillance do not necessarily reflect the opinions of the European Centre for Disease Prevention and Control (ECDC) or the editorial team or the institutions with which the authors are affiliated. Neither ECDC nor any person acting on behalf of ECDC is responsible for the use that might be made of the information in this journal. The information provided on the Eurosurveillance site is designed to support, not replace, the relationship that exists between a patient/site visitor and his/her physician. Our website does not host any form of commercial advertisement. Except where otherwise stated, all manuscripts published after 1 January 2016 will be published under the Creative Commons Attribution (CC BY) licence. You are free to share and adapt the material, but you must give appropriate credit, provide a link to the licence, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.

Eurosurveillance [ISSN] - ©2007-2016. All rights reserved

This website is certified by Health On the Net Foundation. Click to verify. This site complies with the HONcode standard for trustworthy health information:
verify here.