|Last Winter's Epizootic In Europe|
Germany's FLI (Friedrich-Loeffler-Institut) today has published a new risk assessment on the potential return of HPAI H5 this winter to Europe.
When H5N8 returned to Europe in the fall of 2016 after an 18-month absence it brought with it new virulence, an expanded host range, and significant genetic changes (see EID Journal: Reassorted HPAI H5N8 Clade 220.127.116.11. - Germany 2016).
This newly reassorted H5N8 virus - which had previously made only brief appearances in Europe - went on to produce the largest epizootic in European history.Today's risk assessment, while focusing on H5N8, also makes note of (as recently have both the UK's DEFRA and the ECDC) of H5N6, which is feared could eventually wing its way from Asia into Europe as have H5N8 and H5N1.
Risk Assessment, 08.11.2017
The HPAI H5N8 epidemics, which has caused more than 1,150 deaths in wild birds and 107 outbreaks in captive birds (92 poultry holdings and 15 zoos/wildlife parks) in Germany since 8 November 2016, ebbed away in spring 2017.
However, further HPAI H5N8 infections have been observed in Germany since then (three dead mute swans in the South Harz region, Saxony-Anhalt, in August and one shot mallard duck in Lower Saxony in October 2017).
In June a series of epidemiologically linked outbreaks occurred in Europe in captive birds in Belgium (10) and Luxemburg (4). In addition to sporadic outbreaks in Great Britain (1), Belgium (2), and Northern France (1), particularly Northern Italy has been affected from outbreaks in poultry since June 2017. Two further outbreaks in poultry holdings have been detected in Bulgaria.
Furthermore, a total of 16 HPAI H5N8 cases were reported in mute swans, mallard ducks, and one grey heron in Great Britain (1), Switzerland (12), and Italy (3) in August and September.
Outside Europe, HPAI H5N8 outbreaks in poultry have been confirmed since June 2017 in Nigeria, Simbabwe, South Africa, and the Democratic Republic of Congo, as well as in the Asian part of the Russian Federation. HPAI H5N1 Clade 18.104.22.168c is endemic in Asia and in some African countries, e.g. in Egypt. Furthermore, other H5 strains related to HPAIV H5N1 are circulating in Asia.
Genetic investigations and the determined relationship between HPAIV H5N8 detected in wild birds since June indicate that since its first introduction to Europe in October 2016 the virus has persisted in Europe at least in those regions where the most recent cases of HPAIV H5N8 have been detected.
Therefore, it must be assumed that there is a risk of new infection chains which will increase with the number of susceptible water birds during fall migration. Biosafety measures in poultry holdings should be reviewed and optimized. The most effective protection of poultry from infection is to prevent direct and indirect contact between poultry and wild birds.
So far, none of the HPAIV subtypes detected in Europe has been found to cause clinical disease in humans. However, subtype H5N6 of clade 22.214.171.124c (so far only detected in Asia) is being observed with increased attention due to its zoonotic potential.
In summary, the risk of introduction and spread of HPAIV H5 in domestic poultry holdings is assessed as follows: