Shiga toxin-producing E. coli (STEC), Taenia solium, and plant-based products were among topics discussed at the latest meeting of a European network focused on risk assessment.

The Scientific Network on Microbiological Risk Assessment (MRA Network) includes 25 member states plus Switzerland and Norway as observers. It is coordinated by the European Food Safety Authority (EFSA).

A range of topics were presented at a meeting in October 2023 including pathogenicity of STEC, risks due to power failure, heating and refrigerated storage of eggs, milk from dairy farms with botulism, Echinococcus eggs on berries, Salmonella in the pork chain, Campylobacter transmission routes, Listeria monocytogenes in ready-to-eat foods, pathogenic Enterobacteriaceae in cakes, and an update on a Taenia solium outbreak.

E. coli and botulism
The French Agency for Food, Environmental and Occupational Health and Safety (Anses) has reviewed its 2017 opinion on the pathogenicity of STEC. Based on the analysis of surveillance data from 2017 to 2021, the agency proposed a new classification of STEC strains according to virulence potential. This classification takes into account the association of strains with severe forms of infection such as hemolytic uremic syndrome (HUS), which attacks the kidneys, and bloody diarrhea.

STEC strains with stx2a and/or stx2d and adherence genes, eae or aggR, have the highest potential to cause HUS. eae or aggR-negative strains with stx2a and/or stx2d variants also have a high potential to cause HUS, particularly in adults. Strains with other subtypes of the stx gene are less frequently associated with HUS and are mainly found in patients with bloody diarrhea and diarrhea.

In 2023, Salmonella Enteritidis was found in layer hens for the first time in decades in Sweden. Millions of eggs were recalled and at least 79 people were sick. A study assessed whether soft boiled eggs from recalled batches could still be safe to eat. If the yolk is creamy but firm, a temperature of at least 65 degrees C (149 degrees F) will be enough to kill Salmonella Enteritidis.

The German Federal Institute for Risk Assessment (BfR) assessed the risk of contracting botulism from the consumption of dairy products if milk from healthy cows is processed that originates from a farm with cases of botulism in the dairy herd.

The agency found the risk of getting botulism from consuming milk and dairy products was very low. It advised consumers not to store raw milk unrefrigerated and that raw farm-gate milk should be boiled before drinking.

Three neurological cysticercosis cases caused by Taenia solium were detected in children in Lier, Belgium. Affected children were diagnosed in 2023, they had no travel history and the only link is that they go to the same school, though are in different classes because they have different ages. In October, a fourth child infected with the pork tapeworm was found. They had no symptoms of illness but were examined as a precaution.

Infection probably occurred more than a year ago. The investigation is focusing on people in contact with the children at school, especially people handling their foods, but not on food itself.

Pathogens in plant-based products
The prevalence and growth potential of Listeria monocytogenes was evaluated in a study for three pre-packed, plant-based RTE food categories on the Belgian market – sliced vegan and vegetarian deli sandwich fillings, fresh cut leafy vegetables, and multi-ingredient salad bowls.

Experts also discussed risks associated with plant-based dairy and meat substitutes. Four outbreaks were covered because of cheese alternatives with three caused by Salmonella and one by Listeria. Irish representatives requested an exchange of studies on the topic following a recall in the country related to a listeriosis outbreak caused by a vegan cheese.

A European study identified DNA of the parasites Echinococcus multilocularis and Echinococcus granulosus sensu lato on lettuces and berries from several EU countries, including berry samples from the Netherlands. While results represented an important step towards understanding the contribution of food sources to human infections, viability of the eggs could not be assessed.

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