Three deaths are being investigated as part of a listeria outbreak linked to desserts supplied to NHS hospitals and care homes.

The UK Health Security Agency (UKHSA) confirmed it is investigating the deaths as well as two non-fatal cases between May and December of last year.

One death was recorded as listeriosis. Two other people were known to be infected with listeria bacteria at the time of their death.

The bacteria was detected in a chocolate and vanilla mousse and a strawberry and vanilla mousse, both supplied by Cool Delight Desserts, UKHSA said – although they have not been confirmed as the source of the infections.

The threshold of listeria found in the desserts was known to be below the legal threshold of what healthy people can tolerate, the PA news agency reported.

The Food Standards Agency said that the desserts were being removed from the supply chain as a precaution while investigations continue.

The five patients were aged between 68 to 89. All had underlying health conditions and were in hospital at the time of infection.

Treated from May to December 2024, two were in Yorkshire and Humber, one in the North West of England, another in the West Midlands and one in Wales.

Listeriosis is a rare infection that is caused by eating food contaminated with listeria bacteria. The outbreak was discovered as part of a routine surveillance in February 2025 at an NHS hospital in the South West.

Dr Gauri Godbole, deputy director for gastrointestinal infections, food safety and one health at the UK Health Security Agency said NHS Trusts and those providing care to vulnerable people had been advised to stop serving these desserts while investigations were under way.

She added that most people affected by listeriosis will have no symptoms or experience mild diarrhoea which subsides in a few days.

“Those who are more vulnerable like the severely immunocompromised or those with advanced aged can be at risk of severe illness such as meningitis and life-threatening sepsis.”

Listeriosis in pregnancy can cause very serious illness in mothers and their babies, and in babies up to one month old.

According to the NHS, listeria can contaminate a wide range of foods, but most infections are caused by eating chilled, ready-to-eat foods.

The BBC has contacted Cool Delight Desserts and the NHS for comment.