The number of Listeria infections fell in 2020 in England and Wales, according to recently released data.

In total, 124 cases of listeriosis were reported in England and Wales in 2020, which is the lowest amount in several years. In 2019, 144 cases were recorded.

There were two outbreaks in England. One was a national epidemic with four cases associated with smoked salmon. Two people died. The other caused two illnesses from 2018 to 2020 and was linked to prepacked sandwiches served in hospitals.

Surveillance of listeriosis in England and Wales is coordinated by the Gastrointestinal Infections and Food Safety (One Health) Division at the UK Health Security Agency (UKHSA). New cases are reported by local clinical laboratories, and health protection teams and by the referral of Listeria monocytogenes isolates to the Gastrointestinal Bacteria Reference Unit (GBRU) for whole genome sequencing (WGS).

Incidence rates were highest in people aged 80 years and older.

Often a serious infection
Overall, women were more affected than men. However, reported cases among men aged 60 to 69 were four times higher than in women in this age bracket. Of 21 cases in people aged 10 to 39, 19 were female and 16 were associated with pregnancy.

Pregnancy-associated infections accounted for a sixth, or 25 cases, which was a higher percentage than in previous years. More than a third of such cases resulted in stillbirth or miscarriage.

Overall, 29 people died and 17 had listeriosis recorded as a cause of death on the death certificate.

Incidence varied geographically, with the lowest in the North West and the highest in the East Midlands. In Wales, eight cases were reported.

October was the peak month for listeriosis reporting in 2020, with no outbreak influence. In 2019, case numbers peaked in May, with one outbreak influencing this finding.

Between January and October 2020, an outbreak was detected in England involving four people, including a pregnancy-related case. One sick person reported consuming salmon trimmings and smoked salmon slices purchased from a UK supermarket chain.

Whole genome sequencing analysis of food isolates from smoked salmon in an EU country identified the outbreak strain. Samples were traced back to a salmon supplier in the UK that distributed products to the retailer reported by one patient.

Listeriosis is a rarely reported disease in England and Wales but the outcome of infection in pregnancy-related cases remains severe, said, officials.

“Two national outbreaks were traced back to high-risk foods for listeriosis. As a predominantly foodborne infection, awareness of high-risk foods for vulnerable groups is vital. It remains imperative that sporadic cases of illness and clusters of the disease continue to be monitored and investigated to inform the continued risk assessment of the food chain.”