Bird flu UK 2022: why is outbreak so bad? Avian influenza symptoms, causes, and impact on food explained

The UK is currently battling what scientists have described as the UK’s worst ever bird flu outbreak.

Government statistics show that since autumn 2021, more than 5.5 million birds have either died from avian influenza or have been culled in a bid to stop the spread of the virus. 2.3 million of this figure have been slaughtered in October 2022 alone.

There have been several human cases too in the UK, although bird-to-human transmission remains rare. There are fears the outbreak could lead to a Christmas turkey shortage, with prices already rising at most of the major supermarkets.

It comes as farmers have already been hammered by rises in production costs stemming from the Russia-Ukraine war and the inflation crisis. Feed costs have soared, while the energy required to light and heat bird housing has also rocketed in price.

So why exactly is this bird flu outbreak so bad - and what does it mean for food supplies? Here’s what you need to know.

What is bird flu?

Bird flu is a type of influenza virus, which is a family of viruses that also give humans the flu. However, bird flu typically occurs in birds only, hence the name.

Influenza is a completely different category of virus to the coronavirus - the type of virus Covid-19 is. As with all viruses, avian influenza either has a low pathogenicity - i.e. it only causes minor symptoms - or high pathogenicity, whereby it is more likely to be fatal.

Birds with the low pathogenicity form of bird flu tend to get minor breathing problems and might not produce as many eggs. However, those with highly pathogenic strains can display a whole host of symptoms, including: unresponsiveness, closed and excessively watery eyes, a swollen head and tremors.

Typically, avian influenza is only something that strikes the UK during the autumn, winter and spring months when birds tend to migrate to our islands. But what has been unusual over the last three years is that it has stuck around throughout the summer months too.

Why is this bird flu outbreak so bad?

According to Dr Thomas Peacock, a virologist at Imperial College London, the current outbreak is the UK’s “worst ever” because the influenza virus has “never been as sustained as we’re seeing now”.

He said: “In previous years the UK has seen a mix of different avian influenza strains (usually only in the winter seasons). The past couple of years have been largely a single strain – a highly pathogenic H5N1.

“There appears to be much more virus in the wild migratory birds than previous years. This is leading to mass die offs in sea birds, but also the virus appears to be staying with us over the summer, whereas in previous years the virus would go away in the warmer seasons.”

Dr Peacock says the current thinking is that it could be due to changes to this particular strain of the virus, or it could be due to a change in how birds behave - for example, they may have altered their migratory patterns. But scientists do not know the exact reason.

What is clear though is that we have probably not yet seen the worst of this bird flu outbreak. Indeed, the UK’s chief veterinary officer Dr Christine Middlemiss has said she expects the number of cases to “continue to rise” over the coming months.

“Avian influenza usually peaks in the winter and it’s looking to be at least as bad as the previous two winters,” Dr Peacock says. “It is fairly concerning that this virus is acting in a way we haven’t seen it act before.

“The UK is not considered an area where avian influenza is endemic (and instead we suffer seasonal, migratory epidemics in our wild birds and poultry). However, a few more years of year-round circulation and that might have to be reconsidered. This will likely also lead to further year-round heightened biosecurity on poultry farms.”

The upshot of this, Dr Peacock says, is that UK-reared, high welfare free-range eggs could disappear from supermarket shelves over the long term.

What does the bird flu outbreak mean for food?

Unless you live on or near a farm, it’s unlikely you will have noticed the bird flu outbreak currently sweeping across the UK.

From 17 October, farms in England have had to keep their flocks indoors as part of Avian Influenza Prevention Zone (AIPZ) rules. Wales, Scotland and Northern Ireland have not followed suit.

The AIPZ requires birdkeepers - whether they’re people who have a few hens in their garden or commercial farms with thousands of birds - to shut their birds indoors, regardless of whether they are free range or not.

Typically, these rules see birds remain indoors until late spring, so it is likely free range eggs will disappear from supermarket shelves in February (they can be called free-range until birds have been housed indoors for over 16 weeks).

But British Lion, the organisation providing the quality assurance kitemark you see on most UK eggs, insists this situation will not lead to a major degradation of the welfare of UK flocks - although free range hens may need time to adapt.

“All free range hen houses are designed to stock birds in the same numbers as barn hens, who live permanently inside similar barns. Birds are free to roam around the house and have nesting boxes, perching areas and scratching areas,” said a spokesperson.

“They have continuous access to feed and water. Producers will be spending time with their birds and will make sure they have some additional activities, for example hanging items like hay nets for them to play with, to ensure that their welfare is not affected while they adapt.”

The organisation said it was “working closely with retailers” to make sure it could keep up with consumer demand.

When it comes to birds reared for their meat, like chickens and turkeys, there are unlikely to be any serious shortages. Government figures show 5.5 million birds have been killed over the last 12 months or so as a result of the bird flu outbreak. Richard Griffiths, the CEO of trade organisation the British Poultry Council, told BBC Radio 4 in October that around a third of free range turkeys reared for the 2022 festive season had been lost to bird flu.

But, with 20 million birds slaughtered for human consumption every week in the UK, it is unlikely you’ll see any widespread shortages of chicken or turkey.