When the H5N8 virus returned to Europe last fall, it brought with it a number of genetic changes likely picked up from a reassortment event the previous spring or summer in Russia or China (see EID Journal: Reassorted HPAI H5N8 Clade 18.104.22.168. - Germany 2016).
With these genetic changes came some significant behavioral changes as well.This rebooted HPAI virus has demonstrated remarkable geographic spread (including to Africa and the Middle East) over the past year, increased virulence in wild birds, a much greater avian host range, and unusual environmental persistence deep into summer.
While the UK hasn't been particularly hard hit this summer (1 poultry outbreak), the same cannot be said for Italy, and to a lesser extent Belgium, Luxembourg and France. Wild bird reports have also come from Germany, Switzerland, and the Netherlands (see DEFRA: Outbreak Assessment On H5N8 In Europe - Summer 2017).
Unlike we've seen in year's past - this summer, at least - H5N8 has has just never quite gone away.And with this fall's migratory bird season ramping up, the threat to poultry interests across Europe is only expected to increase in the months ahead. Today the UK's DEFRA released a new infographic (see top of blog), and biosecurity advice for poultry holders going into this winter.
Both refer to the `constant risk' of avian influenza in the UK.
If you keep poultry or other captive birds, you must keep a close watch on them for any signs of disease.In another DEFRA release, published today:
- there is a constant risk of bird flu in the UK from wild birds. As it’s highly contagious you need to take action to protect your birds from catching it
- any very sick birds, or unexplained deaths, must be assessed by your vet. By law suspicion of bird flu is notifiable (you must tell us). Bird flu can affect poultry movement and trade
- clean footwear before and after visiting your birds. Keep areas clean and tidy, and regularly disinfect hard surfaces. Humanely control rats and mice
- place your birds’ food and water in fully enclosed areas that are protected from wild birds, and remove any spilled feed regularly
- keep your birds separate from wildlife and wild waterfowl by putting suitable fencing around the outdoor areas they access
- sign up for free online to receive alerts on any outbreaks of bird flu, and register your birds
Poultry keepers urged to take action now to prepare for winter Avian Flu threat(EXCERPT)
Published: 1 September 2017
The Chief Vets of Wales, Scotland, Northern Ireland and the UK are encouraging keepers to take action now to reduce their disease risk
Last winter, the H5N8 strain of bird flu was found in 13 kept flocks in the UK – ranging in size from as few as nine to as many as 65,000 birds. We have seen a decline in the number of new cases over the summer, but the disease is still circulating in kept poultry across Europe, with Italy the most recent country to suffer a series of outbreaks. It has also recently been confirmed in a dead mute swan in Norfolk.(Continue . . . )
And a bit of added emphasis comes from FarmingUK, which today published:
(Excerpt)1 September 2017 09:18:56
Egg producers urged to be ready to protect from 'year round' bird flu threat
FarmingUK asked Defra whether it was concerned about the number of cases of H5N8 in both poultry and wild birds now arising outside the traditional winter high risk period.
He said: "Our risk level is currently low, which means that outbreaks and wild bird cases are not entirely unexpected.
"At present, it is too early to say how long this virus will continue to circulate - other member states (of the European Union) continue to report disease.
"Historically, when this type of event has occurred in Europe, virus may still circulate for several years. We carry out routine surveillance in the UK and horizon scanning and monitoring around the world to help us anticipate future threats to animal health.
Until recently, HPAI H5 didn't appear to persist long term in wild and migratory birds (see PNAS: The Enigma Of Disappearing HPAI H5 In North American Migratory Waterfowl). Instead, it was believed that natural immunity in aquatic birds would - over time - defeat the virus, and it would require fresh introductions of new strains (presumably from poultry) to revive the threat from migratory birds.
This likely explains why, after the North American epizootic of 2014-15, the virus hasn't returned.The $64 dollar question this fall and winter is whether this new-found persistence of H5N8, combined with its increased host range, will alter this pattern. If the virus withered and died over the summer in the high latitude migratory bird roosting areas, then avian flu may be less of a threat this winter.
If, as postulated last year in Sci Repts.: Southward Autumn Migration Of Waterfowl Facilitates Transmission Of HPAI H5N1, one or more HPAI viruses survived the arctic summer, we could see a fresh round of outbreaks this fall in Europe, Asia, and potentially even North America.
And since avian viruses are continually evolving, there's always a Forrest Gump moment every fall, since we never quite know what we're going to get.Since the best offense with bird flu is a good defense, enhanced biosecurity across Europe, Asia, and North America are going to be essential.