|HPAI H5N6 in Europe from 1st October 2017 to 3rd May 2018|
While reports of HPAI this past winter in Europe have been subdued compared to the previous year's H5N8 record epizootic, a newly reassorted H5N6 virus did arrive last December, and a smattering of H5N8 cases have been reported.
As we've discussed previously, a major bird flu season is generally followed by one or more less severe years (see chart below), and so this recent lull is not unprecedented.
We get our most detailed updates on Europe's avian flu situation from the UK's DEFRA (see April's UK DEFRA: Update On H5N6 HPAI UK/Europe & H5N8 HPAI In Europe) and France's ESA Epidemiosurveillance Santé Animale (see ESA Epidemiological Update: Global Circulation Of Avian Flu).
Today (May 22nd) the ESA has published a new report, covering the spread of Clade 126.96.36.199. viruses over this past winter (Oct 1st - May 3rd) in Europe. I've included some translated excerpts, but you'll want to follow the link to read the full report.
Epidemiological situation of HPAI viruses from clade 188.8.131.52 in Europe as of 3rd May 2018
Submitted by Alizé MERCIER on 22. May 2018 - 11:40.
For the Epidemic Intelligence team (VSI) (in alphabetical order): Anne Bronner (DGAL), Didier Calavas (Anses), Julien Cauchard (Anses), Sylvain Falala (Inra), Alizé Mercier (Cirad)
For the National Hunting and Wildlife Agency (ONCFS): Anne Van De Wiele
Corresponding author: firstname.lastname@example.org
Sources: Data updated on 3rd May 2018 (included) ADNS/FAO/OIE, DGAL (General Directorate of Food – French Ministry of Agriculture), ProMED
Since the last situation report on 26th March 2018, the highly pathogenic avian influenza (HPAI) virus of subtype H5N6 has been reported for the first time in Slovakia on 28th March in wild birds (the virus was detected in a black-headed gull (Chroicocephalus ridibundus) among five birds found dead), and in Finland with two cases reported on 3rd and 24th April in white-tailed eagles (Haliaeetus albicilla).
The H5N6 virus was also identified in wild birds in other countries:
The H5N6 virus has also been notified in captive wild birds with a case reported in Sweden on 9th April in a non-commercial holding of 105 birds (species not mentioned).
- Denmark: 22 new reports involving five white-tailed eagles (four reports on 23/04 and one report on 30/04), ten common buzzards (Buteo buteo) (nine reports on 24/04 and one report on 12/04), two mute swans (Cygnus olor) (reports on 23/04 and 24/04), a great cormorant (Phalacrocorax carbo) (report on 23/04), a herring gull (Larus argentus) (report on 23/04), a black-headed gull (report on 23/04), and two hooded-crows (Larus argentus) (reports on 12/04),
- Germany: a case in a white-tailed eagle (report on 30/04),
- Sweden: cases in two white-tailed eagles (reports on 09/04 and 26/04), in a common buzzard (report on 26/04), and in a Northern goshawk (Accipiter gentilis) (report on 26/04),
- United-Kingdom: a case in two common buzzards (report on 20/04), and
- The Netherlands: a case in a common buzzard (report on 28/03).
The H5N8 virus continues to circulate in poultry farms:
Bulgaria has also reported four outbreaks of H5Nx in duck farms on 5th and 25th April.
- Italy: an outbreak reported in a fattening turkey farm (report on 28/03), and
- Bulgaria: four outbreaks reported in three duck farms (reports on 05/04 and 24/04) and in a State hunting reserve (report on 18/04).
From 1st October 2017 to 3rd May 2018 (included), a total of 145 outbreaks of HPAI H5 (including 60 outbreaks of H5N8) were notified in twelve European countries: Bulgaria, Cyprus, Denmark, Germany, Ireland, Italy, the Netherlands, Sweden, Switzerland, the United-Kingdom, Finland and Slovakia (Table 1, Figures 1&2). Two serotypes were identified: H5N6 (Figure 1) and H5N8 (Figure 2).
An H5N2 virus detected in Russia
On 29th December 2017, Russia reported an outbreak of HPAI H5N2 in a poultry farm of more than 660 000 birds, in the region of Kostroma in the Northeast of Moscow (OIE report 29/12/2017). This outbreak was initially notified as H5N8 three days prior.
This is the first report of HPAI H5N2 virus in Russia and the last outbreak of HPAI H5N2 reported in Europe dates back to January 2017 with three outbreaks reported in poultry farms in France.
Regarding the origin of this virus, two hypotheses can be formulated:
- the mutation of a LP H5N2 virus in domestic birds, into a HP virus (as was the case in 2015 with H7N7 in the United Kingdom and Germany, or with H5N1 and H5N2 in France),
- a reassortment between HP H5N8 which circulated in Europe in 2016-2017 with a LP Eurasian strain, as for the H5N6 virus currently circulating in Europe. Indeed, viruses from clade 184.108.40.206 have a strong mutation potential, as illustrated by the emergence of H5N6 and H5N5 viruses following the circulation of H5N8 in Europe in 2016-2017.
Whatever the case may be, further analyses are needed to identify the origin, the link and the genetic composition of these new viruses, and the evolution of the epidemiological situation in Europe should be closely monitored.