In the UK, greater than 150 instances of chicken flu have been reported between September and November of this 12 months alone. Mark Agnor/ Shutterstock
The outbreak of avian influenza which has hit the UK because the autumn of 2021 is the most important the nation has ever seen. And the image is similar throughout Europe and the US, that are reporting an identical image. To date, this outbreak has led to the dying of practically 100 million poultry birds world wide.
But the illness doesn’t solely threaten poultry and egg manufacturing – it additionally threatens wild chicken populations in a method that it by no means has earlier than. While drastic motion has been taken to regulate the unfold of avian flu in home birds, these efforts could also be inadequate alone to mitigate the influence on wild chicken populations.
Typically, western Europe’s avian flu season begins within the autumn, when thousands and thousands of migratory birds from colder climates – akin to geese, geese and swans – arrive for the winter. If these wild birds come into contact with home poultry, any pathogens they’re carrying can unfold to those populations. It’s a time that poultry farmers and different chicken keepers dread, as sure strains of chicken flu (specifically extremely pathogenic avian influenza, also called HPAI) could be extraordinarily lethal. Come springtime, when wild migratory birds return to their summer time breeding grounds in japanese Europe and Asia, avian flu wanes with their departure.
Or, at the very least, that was the sample in current many years. But, because the autumn of 2020, this has modified.
Previous outbreaks of HPAI amongst UK poultry have been comparatively uncommon. But between November 2020 to March 2021, 24 instances of HPAI have been reported. This state of affairs has solely worsened since then, with greater than 150 confirmed instances of HPAI between September 5 and November 17 of this 12 months alone.
Similarly, between 2017 and 2019, solely 40 UK wild birds examined after their dying have been discovered to be constructive for HPAI. But this rose to 317 in 2020-2021 and 1,468 since October 1 this 12 months.
Usually, HPAI causes mass mortality amongst poultry whereas nearly all of wild birds appear much less affected. This is one function that makes the present avian flu outbreak so distinctive. To date, 15 species of seabirds have examined constructive for HPAI for the primary time, and die-offs in some species, akin to nice skuas, are worrying as a result of their magnitude and potential to threaten the species’ persistence within the UK.
Moreover, the seasonal downturn in instances of avian flu didn’t occur throughout the spring as confirmed outbreaks continued amongst poultry and wild birds over the summer time.
Avian flu virus
Bird flu is precipitated primarily by an influenza A virus, which is intently associated to different influenza viruses. These mutate quickly and may mix genetic materials from different influenza viruses into their genomes with the intention to produce new variants.
New strains of avian flu are sometimes imported throughout every chicken migration season. But we’re more and more witnessing new strains rising throughout the UK and different European international locations over winter. The present H5N1 pressure of HPAI, appears to be extra infectious and extra deadly to poultry, and extra persistent in wild chicken populations. It’s additionally capable of have an effect on a higher variety of species than earlier strains.
And, with a higher variety of wild birds contaminated, that is more likely to imply that there have been extra alternatives for contaminated or contaminated wild birds to return into contact with poultry. This can also have contributed to the present excessive variety of instances.
Great skuas have been notably affected.
Gestur Gislason/ Shutterstock
There are nonetheless many issues that we don’t know concerning the present outbreak of avian flu, which is why the federal government has arrange a job power to analyze. One issue this job power is wanting into is whether or not the present pressure can survive within the atmosphere exterior an animal host (a phenomenon referred to as environmental persistence). If that is potential, it might assist clarify why so many wild birds are being contaminated by the present pressure of HPAI – and why outbreaks continued over the summer time.
Containing the virus
The UK authorities has launched a spread of measures to comprise avian flu. All British poultry farms are required to implement stringent biosecurity practices to assist stop their flocks from catching the virus, together with housing free-range birds to forestall contact with wild birds, and repeatedly cleansing and disinfecting housing. Dead wild birds and poultry suspected of getting avian flu are additionally being examined for the virus. If a single chicken in a poultry flock is discovered with avian flu, your complete flock should be culled to forestall the illness from spreading.
Birds are usually not the one species that may turn into contaminated with avian flu. In the previous, some strains have made the bounce to mammals, together with people. There have been 883 reported human instances of a H5N6 pressure (which isn’t at the moment current in Europe) worldwide between 2017 and 2020. But this tended to present itself primarily amongst individuals working very intently with birds. There has solely been one human case of H5N1 reported throughout the present UK outbreak, so dangers to persons are thought possible stay very low. The illness can be successfully managed with a course of antiviral treatment if it does develop.
While measures to regulate avian flu assist mitigate dangers to poultry and other people, they do little to assist wild birds. This might be an issue each for the persistence of the present outbreak and the conservation of some threatened species, that are already beneath stress as a result of human-induced adjustments to the atmosphere.
The rapid future for HPAI seems fairly bleak for the UK which may count on ongoing outbreaks amongst poultry and die-offs amongst wild birds persevering with into subsequent autumn and winter. The authorities’s job power will publish its findings subsequent 12 months, and can reply many questions on the present HPAI pressure. But many extra questions could must be answered earlier than we all know how greatest to get the present outbreak beneath management.
Alastair Ward receives funding from the BBSRC and Defra.
