Data from the UK Health Security Agency (UKHSA) shows Listeria infections rose slightly in 2023 and seven outbreaks were investigated.
In 2023, 177 listeriosis cases were reported in England and Wales compared to 167 in 2022. This is the highest level since 180 infections were noted in 2016.
For non-pregnancy-associated cases, death was reported for 32 people, of whom 11 had listeriosis recorded as a cause of death on the death certificate.
National surveillance of the disease in England and Wales is coordinated by the Gastrointestinal Infections and Food Safety (One Health) Division at UKHSA, with support from Public Health Wales.
Incidence rates were highest in people aged 80 and over. The number of infections was similar in men and women, but for the age groups 20 to 29 and 30 to 39, reported cases among women were higher, as pregnancy-associated listeriosis occurs most commonly in these groups. Of 36 cases in the 20 to 29, 30 to 39, and 40 to 49 age groups, 26 were female, of which 22 were associated with pregnancy.
A total of 29 cases were pregnancy associated, which was comparable to previous years. Of these, 69 percent resulted in live births, 6.9 percent in still births, 13.8 percent in miscarriage, and in 10.3 percent the outcome was unknown.
Incidence varied geographically, with the lowest in Wales and the highest in the South West. Four infections were recorded in Wales while London and the South East had the joint highest with 29 each.
Four solved outbreaks
There were seven outbreaks investigated in England and Wales, including national epidemics associated with smoked fish, semi-soft cheese, and beef products. All these items are high-risk foods for listeriosis in vulnerable groups.
The biggest incident had 15 cases in England and Wales from 2020 to 2023 and was traced to smoked fish. An outbreak with seven patients in these two countries from 2021 to 2023 was linked to cooked beef tongue products.
Six people fell sick in England from 2019 to 2023 after eating corned beef. A semi-soft cheese was linked to three illnesses in England from 2022 to 2023. In three outbreaks with seven cases the source of infection was unknown.
In December 2020, three people were infected with the same strain of Listeria monocytogenes and one died. There was one pregnancy-related case. One sick person reported consuming salmon trimmings and smoked salmon slices from a UK supermarket chain.
Following an inquiry through the European surveillance portal, EpiPulse, WGS analysis of food isolates from smoked salmon in an EU country identified the outbreak strain. Samples were traced back to a smoked salmon supplier in the UK that distributed products to the supermarket reported by one of the cases. Two patients were identified in 2021, seven in 2022, and three in 2023. Where it was possible to complete a questionnaire with the case or next of kin, all reported having smoked salmon products.
In the cheese outbreak, three people were infected with the same strain of Listeria and one person died. They all reported eating the same brand of pasteurized rind washed semi-soft cheese. Affected products were recalled and production ceased voluntarily at the implicated producer. No further cases occurred following this action.
“While the low number of reported cases complicates the interpretation of trends and any comparisons with previous years, it remains important that cases of illness and clusters of disease continue to be monitored and investigated to inform the continued risk assessment of the food chain and implementation of control measures to protect public health,” said the UKHSA.
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