Data from the UK Health Security Agency (UKHSA) shows Listeria infections rose slightly in 2023 and seven outbreaks have been investigated.
In 2023, 177 cases of listeriosis were reported in England and Wales, compared to 167 in 2022. This is the highest level since 180 infections were identified in 2016.
For non-pregnancy-related cases, death was reported for 32 people, 11 of whom had listeriosis listed as the cause of death on the death certificate.
National surveillance of the disease in England and Wales is coordinated by UKHSA’s Gastrointestinal Infections and Food Safety (One Health) division, with support from Public Health Wales.
Incidence rates were highest in people aged 80 years and older. The number of infections was similar in men and women, but for the 20 to 29 and 30 to 39 age groups, reported cases were higher among women, as pregnancy-related listeriosis is most common in these groups. Of the 36 cases in the 20 to 29, 30 to 39 and 40 to 49 age groups, 26 were women, of which 22 were related to pregnancy.
A total of 29 cases were pregnancy-related, which was similar to previous years. Of these, 69 percent resulted in live births, 6.9 percent in stillbirths, 13.8 percent in miscarriage, and in 10.3 percent the outcome was unknown.
The 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 highest numbers at 29 each.
Four resolved outbreaks
Seven outbreaks have been investigated in England and Wales, including national epidemics linked to smoked fish, semi-soft cheese and beef products. All these products are high-risk foods for listeriosis in vulnerable groups.
The largest incident had 15 cases in England and Wales between 2020 and 2023 and was traced to smoked fish. An outbreak involving seven patients in these two countries between 2021 and 2023 was linked to cooked beef tongue products.
Between 2019 and 2023, six people in England became ill after eating corned beef. A semi-soft cheese was linked to three diseases in England between 2022 and 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 case related to pregnancy. One sick person reported consuming salmon chips and slices of smoked salmon from a British supermarket chain.
Following an investigation through the European surveillance portal EpiPulse, WGS analysis of food isolates from smoked salmon in an EU country has identified the outbreak strain. The samples were traced to a smoked salmon supplier in Britain who distributed products to the supermarket reported in 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 that they had smoked salmon products.
During the cheese outbreak, three people were infected with the same Listeria strain and one person died. They all reported eating the same brand of pasteurized, rind-washed, semi-soft cheese. The affected products were recalled and production at the affected manufacturer was voluntarily halted. No further cases occurred after 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 and disease clusters continue to be monitored and investigated to support the ongoing risk assessment of the food chain and the implementation of measures. control measures to protect public health,” the UKHSA said.
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