Almost 1.8 million farmed and captive birds have been culled in the past three months because of the spread of avian flu across the UK, the BBC has learned.

There have been 33 outbreaks of the virus on farms and, on Wednesday, the government said bird-keepers in five more English counties would have to house flocks indoors from Sunday.

The risk to humans remains low, with chicken and eggs safe to eat if properly cooked, but there are concerns about the impact bird flu is having on farmers’ mental health.

The government said it had acted quickly to cull all poultry on infected premises “to protect Britain’s food security”, but recognised the devastating impact it was having.

A spokeswoman for the Department for Environment, Food and Rural Affairs (Defra) said the 1.78 million birds culled since the first outbreak on 5 November was a “small proportion” of the industry’s total production, which is about 20 million birds a week.

At the beginning of the worst outbreak of bird flu, 3.2 million birds were culled between October 2021 and September 2022.

One of those farmers affected in 2021 was Lucy Sanderson, from North Yorkshire, who says people are not aware of the mental health impact culling birds had on farmers.

“It was awful. I cried for a week – and I thought I was a strong person,” she said.

“As well as losing my job, my income, my everyday life, I also ruined my staff’s lives as I had to make them redundant. The knock-on effect was huge.

“I am terrified of it returning.”

Gary Ford, of the British Free Range Egg Producers Association, said there was “a lot of worry and concern amongst poultry farmers and, in some respects, panic”.

Biosecurity restrictions are currently in place across England, Wales and Scotland as part of an Avian Influenza Prevention Zone.

On Wednesday, it was announced that all farmers and bird-keepers in Herefordshire, Worcestershire, Cheshire, Merseyside and Lancashire will also have to house their flocks from midnight on 16 February.

Housing orders are already in place across East Riding of Yorkshire, City of Kingston upon Hull, Lincolnshire, Norfolk, Suffolk, Shropshire, York and North Yorkshire.

James Mottershead, chairman of the National Farmers’ Union poultry board, said bird flu outbreaks were putting a “huge emotional and financial strain on farming families”.

“Farmers take such care to protect the health and welfare of their birds and it’s devastating to see that compromised,” he added.

A Defra spokeswoman said compensation would be paid to any farmer for all healthy birds that have been culled for disease control purposes.

“We know the devastating impact bird flu has had on farmers and poultry producers, which is why we have taken further measures in recent weeks, including introducing housing orders in the most affected areas,” she said.

“We have acted quickly to cull all poultry on infected premises to stop the risk of the disease spreading and to protect Britain’s food security.”