The number of Listeria infections went up in 2021 in England and Wales, according to the UK Health Security Agency (UKHSA).

A total of 160 cases of listeriosis were reported in England and Wales compared to 124 infections in 2020.

National surveillance in England and Wales is coordinated by the Gastrointestinal Infections and Food Safety (One Health) Division at the UK Health Security Agency (UKHSA), with support from Public Health Wales.

Overall, 22 people died, of whom 12 had listeriosis recorded as a cause of death on the death certificate.

Incidence rates were highest in people aged 80 and over. The incidence of listeriosis was lower in men than women, but for the age groups 70 to 79 and 80 and over, reported cases among men were higher than women.

Of 35 cases in the 10 to 19, 20 to 29, and 30 to 39 age groups, 28 were female, and 24 were pregnant. Pregnancy-associated infections accounted for around a fifth of all reported cases, and 20 percent of pregnancy-related cases resulted in stillbirth or miscarriage.

The lowest incidence was in Wales, with five cases, and the highest in London, with 34 infections. September was the peak month for listeriosis reporting in 2021.

The cases in England and Wales returned to levels seen before the COVID-19 pandemic.

“It is likely that the pandemic and associated non-pharmaceutical interventions implemented to control Coronavirus affected gastrointestinal disease surveillance in several ways. It should be noted, however, that the interventions implemented during this period would have been less likely to affect the reporting of listeriosis cases similarly to other cases of gastrointestinal infections due to the greater severity of illness of cases of listeriosis,” according to the report.

Outbreak reports
There were three outbreaks investigated in England and Wales. The sources were cooked beef tongue products, corned beef, and smoked fish, all high-risk foods for listeriosis in vulnerable groups.

Cooked beef tongue products sickened three people. Corned beef affected four people from 2019 to 2021. Five patients were recorded in 2020 and 2021 in the smoked fish outbreak.

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 patients, including one pregnant woman, had underlying conditions or risk factors for listeriosis. One patient reported eating salmon trimmings and smoked salmon slices from a UK supermarket chain.

Whole genome sequencing (WGS) of isolates from smoked salmon in an EU country identified the outbreak strain. Samples were traced back to a fish supplier in the UK that distributed products to the supermarket. Two more patients were identified in 2021. Both reported consuming smoked salmon products.

Climate change impact
Meanwhile, the UKHSA has published a review of indicators relevant for monitoring of climate change and health in England.

Several of the 59 indicators covered food. For “Foodborne outbreaks and/or reported concerns and alerts” and “Incidence of foodborne diseases,” there was a need for new data processing.

Scientists noted food safety risks may change, and the response to climate impacts may involve increased use of pesticides, antibiotics, fertilizers, and chemicals to maximize yields, which could lead to rising chemical contamination of crops and livestock.

Flooding or drought could also affect public water supplies. Outbreaks from water are reported. However, the cause of contamination and the role of weather are not routinely recorded.

Rising temperatures are indirectly linked to risks, including increases in foodborne diseases, according to the report.

“Several epidemiological studies have shown that the incidence of diseases from bacterial contamination is sensitive to temperature. Many gastrointestinal infections are acquired abroad, and there is a need to improve the surveillance of travel-related infections. As with other climate-sensitive diseases, there is a need to establish the role of climate and weather factors in any change in incidence. This needs to be done with expert advice.”