Summary of EFSA Microbiological Risk Assessment Network Activities During 2023

The European Food Standards Agency (EFSA) has published its annual report for the Scientific Network on Microbiological Risk Assessment (MRA Network), summarizing the network’s activities throughout 2023, which were presented at the Annual MRA Network Meeting. The MRA Network facilitates scientific cooperation through coordination, information exchange, and joint projects. At present, 25 EU Member States, plus Switzerland and Norway, participate in the network.

The 23^rd meeting of the MRA Network was held on October 4–5, 2023, both in-person from Parma, Italy and online. A wide range of activities related to microbial risk assessment were presented including:

The pathogenicity of Shiga toxin-producing Escherichia coli (STEC): Based on an analysis of French surveillance data from 2017–2021, the French Agency for Food, Environmental, and Occupational Health and Safety (ANSES) proposed a new classification of STEC strains according to their virulence potential, taking into account strains that cause severe forms of infection, such as Hemolytic Uremic Syndrome (HUS).
Food safety risks due to power failure: In light of the ongoing energy crisis, the topic of refrigerated food safety during a power failure was addressed. A study is examining bacterial growth in food under temperature conditions mimicking a power failure lasting 48 hours. The results will inform guidance on reducing food waste without affecting food safety during a power failure.
Heating and refrigerated storage of eggs: In light of an incidence in Sweden where Salmonella Enteritidis was found in egg layers for the first time in decades, a study was conducted to assess whether soft boiled eggs from recalled batches could still be safe to eat. The results showed that a creamy but firm egg yolk indicates that the temperature is at least 65 °C (149 °F), which will render enough inactivation of S. Enteritidis. Additionally, the Danish Veterinary and Food Administration (DVFA) estimated the risk of increase in the number of egg-related salmonellosis cases by removing the refrigeration requirement for table eggs, while keeping the recommendation for storage at a constant temperature, for both small and large producers. For small producers, there was no increase in the average number of annual illnesses per farm, and for large producers, the annual number of illnesses per farm varied from 0–5, for eggs consumed uncooked or lightly cooked. At the national level, the absolute number of egg-attributed human salmonellosis cases per year varied from 0–35, with an average of 10 cases per year for eggs consumed uncooked and 8 cases per year for eggs consumed lightly-cooked. DFVA pointed out that consumers and producers must be advised that cooling extends the time period before the egg-yolk membrane breaks, and cooled storage remains recommended after the yolk-membrane integrity time is reached.
Milk from dairy farms with botulism: The German Federal Institute for Risk Assessment (BfR) assessed the risk of contracting botulism in Germany from the consumption of processed milk and dairy products originating from healthy cows that live on a farm with acute cases of botulism in the dairy herd.
Echinococcus on berries: Recently, a large European study (OHEJP Meme) identified the DNA of zoonotic parasites Echinococcus multilocularis and Echinococcus granulosus sensu lato on significant quantities of lettuce and berries from several European countries. The results represent an important step toward understanding the contribution of food sources to human infections, even if the viability of the Echinococcus eggs could not be assessed. A further study will be conducted in the E. multilocularis endemic region of Limburg in the Netherlands in order to investigate the current prevalence of E. multilocularis in foxes, vegetables, and berries, and to evaluate the potential association with a higher risk of human infection.
Salmonella in the pork supply chain: A presentation was given to provide an overview of S. enterica in the European pork supply chain, discussing prevalence, serotype diversity, and antimicrobial resistance (AMR) over the past two decades. Future trends and recommendations regarding control of Salmonella in the European pork production chain were also introduced.
Campylobacter transmission routes: Preliminary results were presented from a project that analyzed cases of Campylobacter infections from 2004–2021, foodborne and waterborne outbreaks from 2010–2021, a case-control study conducted in July–August 2022, sequence and cluster analysis of bacteria isolates, and source attribution modeling using MLST allele types. The source attribution and case-control studies indicated similar association of cases with potential sources and genotype clusters. Also, during the COVID-19 pandemic, the overall number of campylobacteriosis cases dropped dramatically.
Listeria monocytogenes growth and presence in plant-based, ready-to-eat (RTE) foods: The prevalence and growth potential of L. monocytogenes were evaluated in a study for three prepacked, plant-based RTE food categories on the Belgian market, specifically, sliced vegan and vegetarian deli sandwich fillings, fresh-cut leafy vegetable mixes, and multi-ingredient salad bowls. The study also investigated the effect of temperatures ranging from 6–43 °C (43–109 °F) on the growth of two genotypically and phenotypically different strains of L. monocytogenes in Tryptone Soy Broth and synthetic cheese medium.
Potential risks associated with plant-based meat and dairy substitutes: The meeting noted four plant-based foodborne illness outbreaks, all associated with cheese alternatives. Salmonella was the cause of three outbreaks, and L. monocytogenes was linked to a single outbreak. In light of a recent recall of vegan cheese contaminated with L. monocytogenes in Ireland, the Irish representative requested an exchange of studies on the risks associated with RTE plant-based dairy and meat substitutes.
Pathogenic Enterobacteriaceae in cakes: Research was conducted to identify which Enterobacteriaceae species are present in cakes from confectionery establishments and whether they are species that can be considered pathogenic for humans, as well as their potential harm to human health. Although ten Enterobacteriaceae species were isolated from food or water, and all but one were also isolated from humans and the environment, none of them were a vehicle in any case of human illness.
Pericarditis in broilers at post-mortem: A literature review was conducted to identify hazards for the development of pericarditis in broilers and assess related risks with potential bacteraemia in affected broilers. The risk for consumers of broilers with signs of pericarditis was determined to be very low.
An update on a Taenia solium outbreak: A cluster of three neurological cysticercosis cases caused by Taenia solium was detected among children living in Lier, Belgium. Cysticercosis is not typically linked to food consumption, but the children may have been infected by a food handler spreading the eggs of the parasite due to insufficient hand hygiene. The investigation is focusing on people in contact with the children at school, especially food handlers, but not on any one food itself.

Additionally, a presentation was given to illustrate Rapid Outbreak Assessments (ROAs) for multi-country foodborne illness outbreaks in the EU, jointly prepared by EFSA and the European Centers for Disease Control (ECDC). The presentation focused on three ROAs published in 2023 and regarding an outbreak of Salmonella Seftenberg ST14 infections linked to tomatoes, an outbreak of Salmonella Virchow ST16 infections linked to chicken meat, and an outbreak of Salmonella Mbandaka ST413 infections linked to chicken meat. EFSA highlighted the importance of sharing whole genome sequencing (WGS) data to support outbreak investigation activities.

EFSA also presented its Focal Point Framework for 2023–2027, which outlines how Member States can propose activities to be implemented under the Focal Point Framework, intended to address risk assessment and food safety needs of both Member States and EFSA.

Finally, activities of the EFSA Panel on Biological Hazards (BIOHAZ) and the Biological Hazards and Animal Health and Welfare Unit (BIOHAW) were presented. Ongoing work is focused on: