FAQs: Avian Influenza

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The UK has experienced an unprecedented avian flu outbreak in 2021-22. Similarly, the European Centre for Disease Prevention and Control stated that the 2021-22 epidemic in Europe was “the largest observed in Europe so far”.

The Rural Affairs, Islands and Natural Environment (RAINE) Committee heard from Scotland’s Chief Veterinary Officer (CVO) Dr Sheila Voas on 30 November on the avian flu situation in Scotland and across the UK. This blog summarises answers to some of the frequently asked questions around the current avian flu outbreak. Use the contents list below to browse the questions.

What is avian flu?

Avian influenza, avian flu or bird flu, is a viral disease that is largely spread between birds. It is similar to, but not the same as other strains of influenza virus that causes flu in humans or in other species.

It can affect different bird species differently, but in the most affected it can cause rapid illness and death. There are both ‘highly pathogenic’ and ‘low pathogenic’ varieties, which refers to the severity with which it affects birds (not humans). The current outbreak is of a ‘highly pathogenic’ variety.

How is avian flu spread between birds?

In wild birds, bird flu spreads around the world with migrating species. For the UK, the Chief Veterinary Officer explained to the RAINE Committee that wild birds, particularly water birds, spend summers in their Arctic breeding grounds where populations from all over the world mix. This causes the virus to mutate from year to year. The birds then fly south to the UK where they spend the winter in different parts of the country. There is usually a winter season for bird flu for this reason, though this year was particularly unusual as cases were found into the summer, particularly in seabird populations.

In commercial or backyard flocks, avian flu usually spreads through direct contact with migrating wild birds or contact with faeces of an infected bird. This can happen via materials such as bedding.

The Chief Veterinary Officer clarified that, at this time of year, it is less likely that the disease will move northward compared to southward, given that migrating birds in the northern hemisphere are generally moving south for warmer weather. She said:

“It is not so much that the disease is likely to spread from England to Scotland. Once the wildfowl reach their overwintering grounds, a cold snap will make them move again, and as it is very unlikely that England will be colder than we are, they will tend not to come north again. However, we are monitoring the weather further north. If it becomes very cold in Norway or Iceland, that might drive even more birds south to us, thereby increasing the risk.”

How bad is the current avian flu outbreak?

The current outbreak is unprecedented. In relation to impacts on commercial flocks , a House of Lords Library briefing published on 14 November 2022 highlights that for the whole of the UK the number of birds culled annually has fluctuated between 0 and 250,000 birds between 2006 and 2020, rising steeply to 3.25m birds in 2022. The Chief Veterinary Officer stated that as of 30 November 2022, 224,000 birds have had to be culled in Scotland; in England nearly 1.7m turkeys and over 2m chickens have had to be culled, as well as ducks and geese. Further outbreaks have been recorded in both Scotland and England since this date.

The outbreak has been particularly severe in some parts of England. As of 21 December, 133 cases have been confirmed in England since 1 October 2022. In the same period, 12 cases have been confirmed in Scotland, and a handful of cases in Wales and Northern Ireland respectively.

The current outbreak is also having a significant impact on wild bird populations, particularly seabirds. In a letter to the RAINE Committee on 22 August 2022, the Cabinet Secretary for Rural Affairs and Islands outlined the impact on wild birds at that point. Some species have been particularly affected. For example, for the great skua, key colonies such as St Kilda, Fetlar, Handa, Noss and Hermaness were reporting 64-85% population reductions in breeding pairs since the last count. Scotland supports 60% of the world breeding population of great skua. In August, the scale of the impact was estimated to be a loss of 7.7% of the world’s breeding population and 12.8% of the GB breeding population.

The letter noted that the full scale of the impact on wild birds will not be known until next year when the birds return to the UK to breed or overwinter.

How can avian flu be prevented?

The Chief Veterinary Officer emphasised that good biosecurity – hygiene measures to prevent the spread of disease – is ‘the single most important thing that people can focus on’ in preventing the spread of avian flu. Other preventative measures include bringing birds indoors to prevent contact with wild birds, though for housing to be effective in significantly reducing the risk of disease it also requires rigorous biosecurity measures to be in place. The CVO used the example of recent outbreaks among housed birds.

It is difficult to prevent avian flu spreading among wild birds. However, the severity of the most recent outbreak of avian flu in wild bird populations has given rise to some precautionary measures. In July 2022, NatureScot advised that public landings (e.g. through boat tours) to 23 Scottish islands should stop during the seabird breeding season, to limit “the spread of avian flu and give seabirds the best possible chance to survive and recover from the current severe outbreak”.

NatureScot has set up a Scottish Avian Flu Wild Bird Taskforce to coordinate activity to monitor and minimise the impact of highly pathogenic avian flu in wild birds.

How can governments respond to avian flu?

The Scottish Government has powers to take steps to reduce the risk of transmission of avian flu. Under the Avian Influenza and Influenza of Avian Origin in Mammals (Scotland) Order 2006, Scottish Ministers have a duty to do one or more of the following if the Scottish Ministers consider it necessary (having carried out a risk assessment) to reduce the risk of spread:

  • Declare an avian influenza prevention zone (APIZ) in all or part of Scotland.
  • Serve a restrictions notice on the occupier of premises where certain poultry or captive birds are kept. The Scottish Government may require birds to be housed or kept separate from wild birds, require that kept birds are provided with feed and water that has not been into contact with wild birds, preventing the use of certain birds as hunting decoys, and requiring extra biosecurity measures.
  • Restrict ‘bird gatherings’ (any situations where birds come together for fairs, markets, shows, exhibitions, etc).

An APIZ has been in place across the whole of the UK since October 2022. The APIZ Declaration for Scotland contains a number of biosecurity measures which must be followed while the Zone is in force. The general licence for bird gatherings has not permitted gatherings of pheasants, partridge, quail, chickens, turkey, guineafowl, ducks, geese, swans or poultry since November 2021.

Can you vaccinate birds against avian flu?

Vaccines are available, but they are not widely used for a number of reasons. Vaccinating captive bird flocks for avian flu is not generally permitted unless it is ordered by Scottish Ministers under specific conditions. This is set out in the Avian Influenza (Slaughter and Vaccination) (Scotland) Regulations 2006. However, Scottish Ministers can order emergency or preventative vaccination in certain situations.

As explained to the RAINE Committee by the Chief Veterinary Officer on 30 November 2022, flu vaccines are ‘suppressive’, rather than ‘curative’. This means that vaccinated birds may not show signs of infection but may still carry and spread the disease. This can be a problem for disease detection and for trade.

She further explained that, in some cases, it is also not practical to vaccinate. Birds need two doses, several weeks apart, which is not feasible in the short lifespan of a broiler chicken (a chicken produced for meat), for example. There are also obvious practical challenges to vaccinating millions of birds regularly. New strains of avian flu emerge frequently, so as with the seasonal flu vaccine for humans, repeated vaccinations are required. However, further research is ongoing.

More information on this can be found on the Animal and Plant Health Agency’s website.

What happens when avian flu is found in wild birds?

Wild birds are monitored for avian flu. The Scottish Government states that:

“The purpose of the surveillance and testing of wild birds is to capture information on the location and strains of avian influenza that might be prevalent in Great Britain. This data then helps government to build up a picture of the current risks, and shapes the response to this risk”

The UK-wide Animal and Plant Health Agency is responsible for monitoring and surveillance of avian flu in wild birds. In Great Britain, if you find:

  • a single dead bird of prey
  • 3 dead gulls or wild waterfowl (swans, geese or ducks), or
  • 5 or more dead wild birds of any other species

at the same place and at the same time, it should be reported to Defra’s national GB helpline. It is advised not to touch sick or injured birds.

What happens when avian flu is found in commercial or backyard flocks?

Avian flu is a “notifiable disease” in domestic flocks. This means that any suspected cases must be notified to the Animal and Plant Health Agency. Failure to do so is an offence.

Where avian flu is confirmed in a commercial or backyard flock, the whole flock will usually be humanely culled. A ‘protection zone’, extending at least 3km around the premises, will be declared. A ‘surveillance zone’ extending at least 10km around the infected premises will also be declared. A number of additional prevention measures are in place within these zones. Measures include, for example, enhanced record keeping, restrictions on moving poultry, and prohibitions on releasing game birds. These rules are set out in the Avian Influenza and Influenza of Avian Origin in Mammals (Scotland) Order 2006.

Is avian flu causing a shortage of eggs or other poultry products?

Avian flu is not directly causing a shortage of eggs but is one of a number of current challenges for egg producers. The National Farmers’ Union of Scotland has highlighted that current input costs are “exceptionally high”, which has made it difficult to receive a sustainable return. This has led to a reduction in the number of chicks placed on UK farms in the last 12 months. The Chief Veterinary Officer explained to the RAINE Committee that bird flu has affected egg production to some extent, but that the effect of increases to the cost of production and low prices to producers have been greater. She said:

“I do not have the Scottish figures, but I believe that the GB figures show that the number of hens on the ground is about 1.7 million down from where it was last year purely because people have chosen not to restock because they lose money on egg production. By comparison, avian flu has killed perhaps 1 million birds but a lot of the people whose flocks were affected are going back into production.”

Turkeys are particularly susceptible to avian flu and turkey production has been badly affected. Scotland has a small number of farmed turkeys, though production is much greater in England (a few tens of thousands of birds are farmed in Scotland, in the context of about 8 million across the UK). The Chief Veterinary Officer told the RAINE Committee that as of 30 November nearly 1.7 million turkeys had been culled in England for the purposes of disease control. MPs in the Environment, Food and Rural Affairs Committee were told by the British Poultry Council on 29 November 2022 that around half of all free-range turkeys have been directly affected. There may therefore be fewer free-range turkeys available this season. The Chief Veterinary Officer told the RAINE Committee that “Turkey may be scarcer, but I am not concerned that there will not be any turkey around this Christmas”.

To secure supplies and livelihoods, producers have been given the option to slaughter and prepare some types of birds early this season, freeze them, and sell them defrosted in supermarkets for a limited time in November and December 2022. These must be marked as “defrosted”.

Is avian flu a threat to humans?

Humans can contract avian flu, though this is rare and usually involves close contact with birds, their droppings or bedding, or in preparing infected poultry. Therefore, the risk to humans from the current bird flu outbreak is considered very low. You cannot catch bird flu from eating fully cooked poultry or eggs.

To prevent infection in humans, it is not advisable to touch sick or injured birds.

Anna Brand, Senior Researcher

Header image by svklimkin from Pixabay