#15,569
After three years of relative quiet, Northern Europe and the UK - and to a lesser extent East Asia - continue to report their biggest surge in HPAI H5 activity (in wild birds & in poultry) since the end of their last major epizootic in the spring of 2017.
The primary culprit - in Northern Europe, at least - appears to be due to a fresh introduction of HPAI H5N8 that has been described as `genetically distinct' from recently circulating strains (see Pre-Print: Novel Incursion of a HPAI H5N8 Virus in the Netherlands, October 2020).
This year's activity is reminiscent of what we saw leading up to the 2016 epizootic in Europe - which (like this year), began over the summer with increased flu activity in Siberia and the discovery of an incursion by a new variant of the H5N8 virus.
Today DEFRA has published their 5th update on avian flu activity in the UK and Northern Europe this fall which lists 5 affected nations (UK, Ireland, Denmark, Netherlands & Germany). The document - while dated November 17th - is already somewhat out of date, as several additional European nations (e.g. Sweden, France, Belgium & Croatia) have reported avian flu over the past few days.The good news is that HPAI H5N8, and its reassorted spinoffs (i.e. H5N5, H5N1, etc.) have not shown the ability to infect humans, and for now, remain only a threat to poultry and wild birds.
Confirmed avian influenza in Koprivnica-Križevci County - CroatiaSweden culls over 3,000 turkeys as bird flu moves through northern Europe - Sweden
Bird flu has returned to Belgium: extra measures announced to contain the virus - Belgium
I've some excerpts from the latest DEFRA report, but you'll want to follow the link to read the report in its entirety. I'll have a brief postscript when you return.
Updated Outbreak Assessment #5
Highly pathogenic avian influenza (HPAI) in the UK, and Europe
17 November 2020
Ref: VITT/1200 HPAI in the UK and Europe
Disease Report
Since our last report on 10 November, in the United Kingdom there have been two new reports of HPAI H5N8 in wild birds, and one new outbreak of HPAI H5N8 in domestic poultry; in Herefordshire. In the Netherlands there have been six reports of HPAI H5N8 in wild birds. Germany has reported 76 cases of HPAI H5N8 in wild birds, and four outbreaks in poultry. Denmark has reported five cases of HPAI H5N8 in wild birds.
Situation Assessment
Since our last report on 10 November, there have been new reports of HPAI H5N8 in wild birds and in domestic poultry in the United Kingdom. The first report in domestic poultry was on 03 November, in the north-west (NW) of England. Since then, on 12 November a second infected premises was reported with HPAI H5N8 in domestic poultry, near Leominster, in Herefordshire. This was a premises with broiler breeder chickens. A 3 km Protection Zone and a 10 km Surveillance Zone have been put in place around the infected premises.
The first report of HPAI H5N8 in wild birds in the UK was on 09 November at a site in Gloucestershire, where five wild birds (a greylag goose and four Canada geese) were found dead on 03 November. On 11 November, there was a second report of HPAI H5N8 in the UK in wild black swans, near Dawlish, in Devon. The third report of HPAI H5N8 in wild birds in the UK was on 12 November, near Weymouth, in Dorset: HPAI H5N8 was identified in one Canada Goose (Branta canadensis) which was found dead on 09 November. As these wild birds are all considered to be native, sedentary species, they must have been infected via introduction by other species of migratory birds.
HPAI H5N8 in Western Europe
Since our last report on 10 November, there have been six further HPAI H5N8 cases in wild birds in the Netherlands. In addition to this, on 10 November there was one report of HPAI H5N8 in 25 captive birds of mixed ‘wild bird species’. These events represent a wide geographical distribution in wild birds and domestic poultry across the Netherlands (see map).
Since our last report on 10 November, in Germany there have been 76 further reports of HPAI H5N8 in wild birds. All continue to be in the north of the country. While the majority were in South Jutland, there were five cases around Hamburg, and a number of additional cases on the island of Rugen and its surroundings. There were also four outbreaks reported of HPAI H5N8 in poultry. Two were in the Northern district of Vorpommern-Rügen: one being a turkey premises of 16,100 birds, and the other a smaller premises of 257 mixed chicken ducks and geese. The other two outbreaks were in Landkreis Rostock (again, in the north of the country), and both were in premises with laying hens, one having approximately 53,000 birds and the other 2,865 birds.
On 13 November, Denmark reported five cases of HPAI H5N8 in wild birds. All were in Jutland, in the Danish regions of Aabenraa, Aalbord, Sonderborg, Tonder and Vejle.
Other HPAI H5 in Western Europe
Since our last report on 10 November, there have been no new reports of other HPAI H5 subtypes in Western Europe.
Implications for the UK
The presence of H5N8 in the UK was not unexpected given the annual autumn migration, and the rapidly developing epidemiological situation (first in southern Russia during the early autumn, and more recently in Continental Europe). Taken together with the findings of HPAI H5N8 in UK domestic poultry in NW and western (W) England, and the wide geographical distribution of the reports in wild birds (in NW, W and southwest of England), this suggests that circulating HPAI H5N8 virus may be widespread in wild birds.
In GB, the sensitivity of surveillance has been increased, to ensure collection and analyses of targeted species of wild birds (ducks, geese, swans, gulls and birds of prey) known to carry risk of infection with H5 HPAI viruses. Single dead birds of target species, where possible, will be collected and tested. Several systems are in place, including working through NGOs (non-governmental organisations), and members of the public reporting wild bird mortality.
The migration season for wild waterfowl to overwinter in the UK has begun, although numbers may not peak until December/January, depending on the species and the weather conditions in Continental Europe. Generally the Netherlands has a far higher number of wintering water birds than the UK, but cold weather on the Continent can force birds to move across the North Sea to the British Isles.
Following confirmation of one Highly Pathogenic Avian Influenza (HPAI) H5N8 outbreak in ‘Cheshire West and Chester’ district of England and one Low Pathogenic Avian Influenza (LPAI) H5N2 outbreak near Dover District, England the UK is no longer free from notifiable avian influenza under the World Organisation for Animal Health (OIE) rules.
Where disease is confirmed, we put in place measures in accordance with Council Directive 2005/94/EC. The EU will put safeguard measures in place, meaning that no trade with the EU in live poultry or poultry products will be permitted from either the Restricted Zone in Kent or the Protection or Surveillance Zone in Cheshire and Herefordshire.
Public Health England has confirmed that the risk to public health is very low, and the Food Standards Agency has said that avian influenza does not pose a food safety risk for UK consumers.
Conclusion
As a consequence of the H5N8 HPAI poultry outbreaks in the UK, and in Germany and the Netherlands; as well as the increasing HPAI H5N8 cases in wild birds in the UK, Netherlands and Germany this week, and the known migration routes on to the UK from these countries: the risk of HPAI incursion in wild birds in the UK is HIGH. The overall risk of infection of poultry in the UK is MEDIUM; although it should be noted that the risk of introduction to individual premises depends upon the level of biosecurity implemented on farm to prevent direct or indirect contact with wild birds.
In response to the increased risk, an Avian Influenza Prevention Zone has been declared in England, Scotland and Wales and the Chief Veterinary Officers from England, Scotland, Wales and Northern Ireland are urging bird keepers across the UK to maintain and strengthen their biosecurity measures; in order to prevent further outbreaks of avian influenza in the UK.
(Continue . . . )
A mentioned at the top of this blog, the HPAI H5 viruses detected in Northern Europe this fall are genetically distinct from other HPAI H5 viruses that have been detected over the past year in Europe. Wageningen Bioveterinary Research (WBVR) center has published the following characterization of these recent isolates, including confirmation that they are similar to viruses which were recently collected in Siberia.
Current avian flu virus resembles viruses found in Egypt, Kazakhstan and Russia
Published on November 18, 2020
A study by Wageningen Bioveterinary Research (WBVR) has shown that the 'new' HPAI H5N8 virus – detected in October 2020 in mute swans in the Netherlands – shares a common ancestor with viruses that were last reported in Egypt in 2018-2019. The new H5N8 virus also has a similar genetic composition. WBVR has investigated the relationship between the viruses in more detail.
Notably, the virus is not directly related to the European H5N8 viruses that were identified in the first half of 2020.
Genetic analysis of the avian flu virus detected in October in the Netherlands suggests that the ancestor of this H5N8 virus has been circulating in Egypt since March 2017 and caused outbreaks there in 2018-2019. After these outbreaks, the virus went unreported until it was detected in the Netherlands in October 2020.
This H5N8 introduction is not related to outbreaks in Eastern Europe, Germany and Bulgaria that occurred earlier in 2020. It also seems unlikely that the H5N8 virus has been circulating unnoticed in the Netherlands in the wild bird population since 2017.
Mute swans do not migrate over long distances, so the virus may have been introduced by other waterfowl species that migrate from their breeding grounds in northern Russia to wintering grounds in the Netherlands. Prior to the bird migration season in 2020, no highly pathogenic avian influenza (HPAI) H5N8 viruses or deaths in wild birds from these breeding grounds were reported. Beginning in August 2020, however, there were several reports of HPAI H5N8 viruses being found in wild birds and poultry in southern Russia and northern Kazakhstan.
Genetic relationship
The sequences of the viruses detected in Russia and Kazakhstan have recently been published, and these suggest a genetic relationship between these viruses and the HPAI H5N8 virus in the Netherlands. Some waterfowl species, such as wigeon, tufted duck and white-headed goose, are known to reside in these regions of Russia and Kazakhstan, from where they migrate to wintering grounds the Netherlands. The HPAI H5N8 virus was detected in a wigeon found near the location of the dead mute swans, which suggests that the wigeon may have introduced the virus to the Netherlands. The virus has also been detected in various species of geese, such as barnacle geese and greylag geese, that also migrate to the Netherlands from their breeding grounds in Russia.
Which means that new variants, genotypes, or reassortments that emerge in the Middle East, China, or Siberia, can - if they are biologically `fit' enough - quickly make their way across continents, and even oceans.
The last major diaspora of HPAI H5 occurred in 2016 (see FAO On HPAI H5's 4th Intercontinental Wave), and the virus spread across Asia, Europe, The Middle East, and a wide swath of the African continent.
While it is too soon to make comparisons, this year's wave of HPAI across Northern Europe appears to be intensifying.
Stay tuned.
