CONCERN is growing as the UK’s “largest ever” bird flu outbreak continues to spread.

The RSPB said High Pathogenic Avian Influenza (HPAI) is affecting a range of poultry operations across the UK.

Wild bird species involved are mostly geese, ducks and swans, but a number of birds of prey have also been confirmed to have died.

Around half a million birds have been culled so far, according to UK chief veterinary officer Christine Middlemiss, who said there are 40 infected premises in the UK – 38 in Great Britain including 33 in England. Ten cases have been reported in North Yorkshire.

An Avian Influenza Prevention Zone was declared across the UK on November 3 before being extended on November 29 with the added requirement all captive birds have to be kept indoors, amid concerns that wild birds migrating from mainland Europe during the winter are carrying the disease.

The risk to human health from avian influenza remains very low, according to public health advice, and there is a low food safety risk.

Speaking in the House of Commons, Environment Secretary George Eustice said: “Each year the UK faces a seasonal risk in incursion of avian influenza associated with migratory wild birds.

“While we have that each year, I have to say this year we are now seeing the largest-ever outbreak in the UK of avian influenza with 36 confirmed cases.”

Defra confirmed the most up to date figure is 40 – 33 in England, three in Wales, two in Scotland and two in Northern Ireland.

In North Yorkshire, culling of thousands of birds has now been carried out at ten premises in the Thirsk, Leeming Bar and Richmond area.

NFU county chairman for the North Riding and Durham, William Maughan, a poultry beef and arable farmer from Darlington and former egg producer of the year, said it is crucial that all captive birds are kept undercover.

"We already have a lot of bio security in place anyway. Since the start of last week we have had to house birds. There is no reason to panic but people need to be aware of what is happening. 

"There are some people who have a few birds in the garden and don’t realise it applies to them as well. All birds have to be kept undercover. Nothing is 100 per cent but we have to keep our standards up to protect our flocks.

"Sometimes the birds have to be culled but that is for the benefit of everyone, to stop the spread of the disease. It is a terrible experience because people care about their stock, but it is necessary. We really sympathise because it is through no fault of their own. 

"The situation this year has been made worse by the mild autumn, that has made the migrating patterns change, which has caused more problems. 

"It is going up that extra level to minimise the effects. We are passionate about the industry and we want to protect our flocks. It is unfortunate that the birds have to be locked up but if that is what it takes, it is necessary.

"There is not much more we can do but make sure everyone gets the message that this applies to all birds. Even if people only have a few chickens or ducks in their garden it is important they are kept undercover, and kept separate from wild birds. It is migrating birds who bring it in, it’s just like the flu season with us."

Dr Middlemiss told the BBC the “phenomenal level” of bird flu has “huge human, animal and trade implications”.

She said the disease is being spread by migratory birds flying back from the north of Russia and eastern Europe.

The vet warned the UK is only a few weeks into a migratory season that goes on until March.

“We are going to need to keep up these levels of heightened biosecurity for all that time,” she said.

The protection zone means that in addition to keeping birds and poultry housed, keepers must continue to take precautions such as regularly cleaning and disinfecting clothing, equipment and vehicles and limiting access to non-essential workers and visitors.

Defra has said the new housing measures will be kept under regular review.

Dr Middlemiss said she is “very concerned” about bird flu, and that having 40 infected premises is “a really high number for the time of year”.

She told BBC Radio 4’s Today programme that around half a million birds have had to be culled.

“I know that sounds a huge number, and of course for those keepers affected it’s really devastating.

“But in terms of food supply impact it’s actually relatively a very small number in terms of egg supply, meat, chicken and so on.”

She said they are continuing to get new detections, adding she confirmed another two on Wednesday night.

Dr Middlemiss said people who keep chickens and want to feed wild birds need to make sure everything is kept “scrupulously clean” and “absolutely separate” to avoid infecting their own flocks.

She said there is an ongoing background risk of bird flu every year, adding that previously there would have been a reasonably sized outbreak followed by two or three quiet years.

“But that’s not happening,” she told the Today programme, adding this is being seen across Europe, with outbreaks last year and some over the summer.

“And now we’ve got this massive increase with the migratory wild birds, and absolutely it’s something we need to understand better about why we are getting these ongoing infections every year,” Dr Middlemiss said.

NFU chief poultry adviser Aimee Mahony said it was a “challenging” time for all bird owners.

“Vigilance is key and poultry farmers are doing all they can to ensure the continued health of their flocks, and that their welfare needs are being met,” she said.

“We are relying on all bird keepers, whether they have a small backyard flock or a commercial business, to follow the enhanced biosecurity and housing measures implemented by the chief veterinary officer to help prevent further disease outbreaks.”

British Poultry Council chief executive Richard Griffiths said they did not expect there to be an effect on overall production “but we, as ever, urge all poultry keepers across the country to remain vigilant and look out for signs of the disease in your birds or bird”.

The British Hen Welfare Trust said it was committed – within legal guidelines and following strict biosecurity procedures – to collecting one more small flock of birds.

A spokesperson added: “However, there will be no further rehoming activity with effect from December 12 until the AI (Avian Influenza) situation improves.

“When it is safe to recommence our lifesaving rehoming work, we will be up and running immediately.”