Three people have died in an ongoing Listeria outbreak linked to fish in the United Kingdom.

The UK Health Security Agency, Food Standards Agency (FSA), Public Health Scotland and Food Standards Scotland (FSS) are investigating the Listeria monocytogenes outbreak that was first made public in April.

Twelve patients across the UK have been identified, including three in Scotland, with onset dates of illness between October 2020 to March 2022.

Ten sick people are over the age of 65, and one is a pregnant woman. Three of those affected who are older than 65 have died.

Six people have fallen ill since January 2022. The majority of patients reported eating smoked fish. 

The FSA and FSS are doing food chain and microbiological investigations including whole genome sequencing (WGS) but the cause is yet to be confirmed.  

In June, Waitrose recalled 2 British Hot Smoked Rainbow Trout Fillets because Listeria monocytogenes was detected in the product. However, there is currently no evidence linking the Listeria found to any outbreak.

Listeria is of concern in chilled, ready to eat foods that do not require further cooking, such as smoked fish.

Information for people who are pregnant has been updated to advise that they thoroughly cook smoked fish before eating it. Smoked fish has also been listed as a high-risk product which should be thoroughly cooked before being eaten by anyone in a high risk group.

Tina Potter, FSA head of incidents, said the public do not need to avoid smoked fish products, but should ensure risks are reduced as much as possible.

“You can do this by keeping chilled ready-to-eat smoked fish cold at 5 degrees C (41 degrees F) or below, always using products by their use-by date, following the storage and usage instructions on the label, and cooking or reheating smoked fish until it is piping hot right through,” she said.

About Listeria infections
Food contaminated with Listeria monocytogenes may not look or smell spoiled but can still cause serious and sometimes life-threatening infections. Anyone who has developed symptoms of Listeria infection should seek medical treatment and tell their doctors about the possible Listeria exposure.

Also, people should monitor themselves for the food poisoning symptoms during the coming weeks because it can take up to 70 days after exposure to Listeria for symptoms of listeriosis to develop.

Symptoms of Listeria infection can include vomiting, nausea, persistent fever, muscle aches, severe headache, and neck stiffness. Specific laboratory tests are required to diagnose Listeria infections, which can mimic other illnesses.

Pregnant women, the elderly, young children, and people such as cancer patients who have weakened immune systems are particularly at risk of serious illnesses, life-threatening infections, and other complications. Although infected pregnant women may experience only mild, flu-like symptoms, their infections can lead to premature delivery, infection of the newborn, or even stillbirth.

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