Listeria outbreaks linked to pre-packaged sandwiches and salads at NHS hospitals in the UK have caused five patient deaths according to Public Health England’s (PHE) latest update on Friday.

A multi-agency investigation into foods linked to the outbreak from supplier The Good Food Chain is underway by PHE, the Food Standards Agency (FSA), Food Standards Scotland (FSS), Public Health Wales (PHW) and Health Protection Scotland (HPS).

The Good Food Chain has voluntarily ceased production while the investigation is ongoing and affected sandwiches and salads were removed from hospitals when the listeria infections were first identified. Evidence suggests that all individuals affected ate the products on 25 May before the foods were withdrawn.

The Good Food Chain is working with FSA during the investigation and has issued a statement saying: “Our thoughts and deepest sympathies are with the families of those who have died and anyone else who has been affected by this outbreak.

“We understand that the investigations being carried out are complicated and will involve a number of stakeholders, but we hope the authorities will pursue their inquiries with all urgency so the wider industry can learn any lessons as soon as possible, and so those affected do not have to wait too long for answers.”

Meat supplied to the business by North Country Cooked Meats produced positive test results for listeria, and the company has also voluntarily stopped production for the investigation.

At the moment patients affected by the listeria outbreaks were at hospitals in England.

FSA chief operating officer Dr Colin Sullivan said: “Our sympathies remain with the families of the patients who have tragically passed away.

“We have taken action along with local authorities to minimise the risk based on the evidence so far. The FSA will continue to investigate the cause of the outbreak to prevent a reoccurrence.”

PHE National Infection Service deputy director Dr Nick Phin said: “To date, there have been no patients linked to this incident outside healthcare organisations, but we continue to investigate. Swift action was taken to protect patients and any risk to the public is low.

“PHE is continuing to analyse all recent and ongoing samples of listeria from hospital patients to understand whether their illness is linked to this outbreak.”

What is listeria?

Listeria is a rare infection and most people affected will not notice or have mild symptoms of gastroenteritis that do not require medical attention. If the infection becomes more serious it can spread to the bloodstream or brain, which is more likely to affect elderly people, young babies, pregnant women and people with a weak immune system.

The illness can develop up to 70 days after being exposed to listeria bacteria.