Listeria outbreak in London linked to consumption of smoked salmon

The UK Health Security Agency (UKHSA) and Food Standards Agency have identified an outbreak of listeria in London, which both bodies say appears be linked to consumption of smoked fish.

There is an ongoing investigation into the listeria outbreak, which is said particularly to affect pregnant women or vulnerable people, often in senior age groups, with underlying health problems, or who are taking medication which could weaken their immune systems.

Professor Geoffrey Alderman, the academic and communal activist, was recently hospitalised at the Royal Free in Hampstead, where he was interviewed by UK Health Security officials about consumption of smoked salmon. He said his wife, Marion, had spent six weeks in hospital earlier this year and it appeared that she had contracted listeriosis, the infectious disease arising from the listeria bacterium.

UKHSA told Jewish News: “Most people won’t have any symptoms of the infection or will only experience mild symptoms such as vomiting and diarrhoea, which usually pass within a few days without the need for treatment”. But the agency warned that all smoked fish — smoked trout, smoked haddock, smoked mackerel and smoked salmon — should be “thoroughly cooked” before eating.

According to the UKHSA: “Whole genome sequencing analysis has identified an outbreak of 12 linked cases of listeriosis since 2020, with six of these since January 2022. Cases have been identified in England and Scotland. The majority of these individuals reported eating smoked fish”. Smoked fish is now designated “a high-risk product which should be thoroughly cooked before being eaten by anyone in a high risk group”.

Tina Potter, head of incidents at the Food Standards Agency, said: “Members of the public do not need to avoid these products, but should ensure risks are reduced as far as possible.

“You can do this by keeping chilled ready-to-eat smoked fish cold (5⁰C 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.”

Narriman Looch, head of animal feed and foodborne control at the FSA, added: “Listeria infections in people who have a normal immune response are rare, and the risk to the general public is low.

“But our advice to vulnerable groups is to only eat smoked fish that has been thoroughly pre-cooked, or to make sure that smoked fish is cooked at home until steaming all the way through.”

Lance Forman, chair and chief executive of H Forman and Son, the smoked salmon specialist, said: “Listeria exists in fish and will grow in warm conditions. But the smoking and curing process will slow down this process, as will refrigeration. Fish should be eaten, in any case, as close as possible to the time of catch, and our salmon is only Scottish so that we can start the smoking and curing process within two days of the catch.”