#15,573
Under the category of `History does not repeat itself, but it often rhymes', four years ago our attentions were focused heavily on the arrival of a recently mutated HPAI H5N8 virus to Europe - one that was far more virulent in birds than previous incarnations - which sparked that continent's largest avian epizootic on record (see EID Journal: Comparison of 2016–17 and Previous Epizootics of HPAI H5 In Europe).
In early January of 2017 we learned that the H5N8 virus had reassorted - likely over the previous summer somewhere in Russia or Mongolia - producing a new, more virulent virus in birds (see EID Journal: Reassorted HPAI H5N8 Clade 2.3.4.4. - Germany 2016).
About the same time, we were also starting to see spin offs of new HPAI subtypes via reassortment (see HPAI H5N5 Detected In German Poultry Operation).
The only good news to be had was - unlike the Asian HPAI H5N1 and HPAI H5N6 subtypes - this lineage of HPAI H5N8 had never been shown to infect humans, and so the public health risk was low.
Over the winter and spring thousands of poultry farms would be affected in dozens of countries, the virus would spread into the Middle East and Africa, and millions of birds (wild and domesticated) would be lost.
And while a return of the virus was feared for the fall of 2017, it never materialized. Instead, a less virulent HPAI H5N6 arrived, making a much smaller impact.
We continued to see scattered reports of HPAI H5N8 - mostly in Eastern Europe, Russia, and the Middle East - but for the most part, avian flu activity globally went into a sharp decline after the summer of 2017 (including H7N9 in China, following a massive vaccination campaign).
After three years of relative quiescence, three months ago we began to get reports of increased HPAI H5 activity in Western Siberia and Kazakhstan, highly reminiscent of the reports that preceded the 2016-2017 epizootic in Europe.
Recent Avian Flu Outbreaks In Russia & Kazakhstan
By October 1st several European Agencies were warning of a possible repeat of the 2016-2017 epizootic (see ECDC & EFSA Warn Of Avian Flu Risk To Europe), and by early November it was confirmed this HPAI H5N8 virus was `genetically distinct' from previous waves of HPAI H5 to arrive in Europe (see Pre-Print: Novel Incursion of a HPAI H5N8 Virus in the Netherlands, October 2020).
While it is far too soon to say whether this year's incursion will match the impact or magnitude of the 2016-2027 event, the similarities are striking.
Yesterday the ECDC published a highly detailed, 20-page scientific report on this latest incursion of HPAI into Europe and the UK. Once again, the zoonotic potential of this virus is deemed low, and no genetic markers suggesting adaptation to mammals have been identified.
I've reproduced the Executive Summary below, and have included some excerpts from their conclusions. Interested parties, however, will want to download the full report.
Avian influenza overview – update on 19 November 2020, EU/EEA and the UKSurveillance report
20 Nov 2020
Publication series: Avian influenza overview
Since 16 October 2020, outbreaks of highly pathogenic avian influenza (HPAI) viruses have been reported in several EU/EEA countries – Belgium, Denmark, France, Germany, Ireland, the Netherlands, and Sweden as well as in the United Kingdom. This scientific report gives an update of the situation up to 19 November 2020 12 pm, with the aim to providing insight into the risk of further spread of avian influenza within the wild bird and poultry populations across Europe, and assesses the zoonotic potential of the virus strains currently circulating.
Executive summary
Since 16 October 2020, outbreaks of highly pathogenic avian influenza (HPAI) viruses have been reported in several EU/EEA countries – Belgium, Denmark, France, Germany, Ireland, the Netherlands, and Sweden as well as in 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).Three HPAI 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 that went 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, and no human infection due to avian influenza viruses detected in the recent outbreaks has 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.
In addition to numerous charts, graphs, and maps, this report contains a list of Conclusions (see below) and a list of Options for Response.
2. Conclusions
• The risk of zoonotic transmission of avian influenza viruses to the general population in Europe remains very low. The evolution of the viruses and recent reassortment events need to be closely monitored in order to assess the ongoing risk of emerging reassorted viruses to transmit to humans.
• Given the low zoonotic potential of these viruses and the strict control measures implemented in poultry holdings related to HPAI viruses (Council Directive 2005/94/EC7), the risk of transmission to humans by eventually contaminated poultry products is considered negligible as outlined also in a previous EFSA assessment (EFSA AHAW Panel, 2017).
• Phylogenetic analysis of the currently circulating HPAI viruses shows that they were different from those that circulated in previous 2019-2020 season. The HA genes of all the identified subtypes belongs to a single genetic group within clade 2.3.4.4b, indicating a single progenitor virus with the highest similarity to North African/Middle Eastern/South-West Asian strains. The different genotypes likely emerged through reassortment events with LPAI viruses circulating in wild birds before arriving in Northern Europe, but the exact location where this occurred cannot be assessed from the currently available data.
• As the southward and westward movements of some waterbird species towards their wintering area continues as part of the autumn migration, there is a high risk of further introduction of HPAI A(H5) viruses to other European countries. The long-distance virus carriers are not known, but possible candidates might include barnacle geese and Eurasian wigeons, given their far eastern breeding range and high frequency of infection (based on the reported data).
• Once introduced into a European country, there is a high risk that HPAI A(H5) viruses can further spread in different directions due to shorter-distance movements of infected birds. Multiple species may be involved in this.
• Besides waterbirds, raptors and other carrion-eating birds are at risk of infection from feeding on contaminated bird carcasses. These species, in particular peregrine falcons and Eurasian buzzards, may be sensitive sentinels for the presence of HPAI A(H5) virus in the environment even when waterbird mortality is low and possibly below detection limit.
• The risk of further spread to unaffected areas via wild bird migrations (and by local movements of residential birds) is high and ongoing. Autumn migration from breeding and staging sites to wintering sites is ongoing and may depend on the weather conditions. The low temperatures of autumn and winter may facilitate the environmental survival of avian influenza viruses. Aggregation during autumn migrations, as well as the mixing of wild birds from different geographic origins during migration, will increase the risk of the infection spreading. Residential infected wild birds (e.g. scavengers) are a sign of an already contaminated environment (e.g. Ireland) and may contribute to disease spread within their range.
• The risk of virus spread from wild birds to poultry is high; Member States should carefully evaluate, also by means of the assessment on avian influenza risk carried out at a national level, the option to enforce in ’high risk areas’ of their territories the measures provided for in Commission Implementing Decision (EU) 2018/11368 to:
i) adopt appropriate AI risk mitigating measures for outdoor poultry;ii) increase disease awareness among stakeholders, and their level of information on biosecurity;iii) strengthen biosecurity in poultry holdings (commercial and rural) with a focus to prevention/reduce the risk of direct/indirect contacts with wild birds;iv) reinforce AI early detection systems in poultry;v) adopt appropriate AI risk reduction measures for the use of decoy birds of the order Ansariformes and Charadriiformes and the release of poultry for restocking supplies of game birds; andvi) guarantee the collection and testing of dead/sick targeted species of wild birds (primarily ducks, geese, swans, gulls and birds of prey) at higher risk of AI.
While HPAI's resurgence has been centered primarily in Europe and East Asia (Japan & South Korea) this fall, we can never know when avian flu will return to Canada or the United States (see H5Nx: Why North America Must Remain Alert).
The USDA has some advice on how to Defend The Flock at the website below.
For more on how avian flu strains from Asia and Europe might make their way back to North America, you may wish to revisit:
