Patients in hospitals under the auspices of Manchester University NHS Foundation Trust and Aintree University Hospital NHS Foundation Trust have been affected, according to the Food Standards Agency (FSA).
Sandwiches and salads linked to the cases have been withdrawn and the supplier, The Good Food Chain, has voluntarily ceased production while the investigation continues.
This business had been supplied with meat produced by North Country Cooked Meats, which subsequently produced a positive test result for the outbreak strain of listeria. This business and North Country Quality Foods, who they distribute through, have also voluntarily ceased production.
Following a product withdrawal, Public Health England (PHE) and Health Protection Scotland (HPS) have written to their respective NHS Trusts and boards to ensure that they are following appropriate food storage and handling protocols and to provide clinical guidance.
Patients in England
The cases linked to the incident all involve patients who were already seriously ill in hospitals in England. Currently, there are no cases in Scotland, Wales or Northern Ireland.
PHE, the FSA, Public Health Wales (PHW), Food Standards Scotland (FSS), HPS and a number of local authorities are currently investigating the source of the listeria infections.
Listeria infection in healthy people is usually either unnoticed or may cause very mild illness. However, it can have more serious consequences for some people, particularly those with pre-existing health conditions and pregnant women.
The health risk to the public remains low and individuals should only seek medical attention if they develop symptoms.
The sandwiches and salads affected are no longer being produced while investigations continue and the affected products were withdrawn from hospitals when the links to the listeria infections were first identified.
“Our thoughts are with the families of those patients who have sadly died," Dr Nick Phin, deputy director at the National Infection Service at PHE said. "We, along with the FSA, colleagues in local authorities and the NHS have worked quickly to determine the likely cause of this outbreak and taken action to reduce the risk to the public’s health.
“To date, there have been no associated cases identified outside healthcare organisations, and any risk to the public is low.”
Dr Colin Sullivan, FSA chief operating officer, said: “Our sympathies are with the families of those 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 how the outbreak occurred and if further steps are required to protect vulnerable groups.”
Listeria infection causes listeriosis, which is a rare infection and for most people it goes unnoticed or there are mild symptoms of gastroenteritis that usually last a short time without the need for treatment.
The time between exposure to the organism and the development of the illness can be up to 70 days.
Occasionally, however, a more serious infection develops and spreads to the bloodstream or brain. This can happen in people who have serious underlying health conditions and can also occur in pregnant women.
Pregnant women and people with underlying health conditions can find more information on the NHS website.
There are an average of 166 annual cases of listeriosis in England and Wales (based on annual case numbers from 2008 -2018). There was an average of 46 deaths in the preceding six years per year (2010–2016).
Earlier this week it emerged that Müller UK had shut down production of two Cadbury dessert lines as a precautionary measure due to the possible presence of listeria in the products. The incident was not linked to any cases of infection.