Listeria cases rose in 2022, with infections linked to 33 deaths in England and Wales.
In 2022, 167 cases of listeriosis were reported. This is up from 160 cases in 2021. A total of 33 people died, and 18 had listeriosis recorded as a cause of death on the death certificate.
Listeriosis remains a rarely reported disease in England and Wales, but the outcome in pregnancy-related cases is often severe, according to the UK Health Security Agency (UKHSA).
The number of cases in 2022 returned to levels comparable with the five years before the COVID-19 pandemic. The reasons for the decrease in cases for 2020 and 2021 are uncertain.
Incidence rates were highest in people aged 80 years and over. Men were more affected than women, except those aged 20 to 29, 30 to 39, and 70 to 79.
The lowest incidence was in the West Midlands, with 10 cases, and the highest was in London, with 38 cases. Only six infections were recorded in the North East, while Wales had eight cases.
July and November were the top months for listeriosis reporting in 2022, with no known outbreak activity influencing these peaks.
Pregnancy-associated infections accounted for 24 reported cases, and 28.6 percent of the pregnancy-associated cases resulted in stillbirth or miscarriage.
The Gastrointestinal Infections and Food Safety coordinate listeriosis surveillance in England and Wales (One Health) Division at the UKHSA, with support from Public Health Wales.
Outbreak details
Four outbreaks were investigated in England and Wales in 2022, including a national incident linked to smoked fish. For two outbreaks, the sources of contamination were cooked beef tongue products and smoked fish, both high-risk foods for listeriosis in vulnerable groups.
A dozen people were affected by the fish outbreak from 2020 to 2022. A few cases were also recorded in Scotland. In late 2022, Lidl recalled smoked trout and salmon from St James Smokehouse. Product testing found Listeria that matched the outbreak strain, but levels were below legal limits. Five people fell sick in the beef tongue outbreak in 2021 and 2022.
Between November and December 2020, an outbreak was detected in England after three people were infected with the same strain of Listeria monocytogenes, one of whom died. All cases had underlying comorbidities or risk factors for listeriosis, and one was pregnancy-related. One patient reported consuming salmon trimmings and smoked salmon slices from a UK supermarket.
Following an international inquiry through the European surveillance portal Epi-Pulse, WGS analysis of food isolates sampled 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 retail chain, as reported by one of the sick people. Two cases were identified in 2021, and seven more in 2022. All had underlying issues or risk factors for listeriosis and reported eating smoked salmon products.
There were also two unsolved outbreaks. One had five cases from 2021 to 2022, and the other had six patients from 2018 to 2022.
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