EHEC is responsible for foodborne infections
While most strains of E. coli do not pose any health risks, certain strains, such as enterohaemorrhagic E. coli or EHEC, are pathogenic because they produce a toxin called Shiga toxin. These strains are also referred to as Shiga toxin-producing E. coli (STEC).
EHEC is responsible for a variety of disorders, ranging from mild diarrhoea to more severe forms, including haemorrhagic diarrhoea and severe kidney disease in the form of haemolytic uremic syndrome (HUS). EHEC infections primarily affect young children, especially those under the age of five, as well as immunocompromised individuals and the elderly. Every year, in France, around 140 cases of HUS are recorded in children.
EHEC is mainly transmitted through food. In France, the foods most often involved in EHEC outbreaks are raw or undercooked beefburgers and raw-milk cheeses. An outbreak that occurred in 2022 was caused by the consumption of raw or undercooked pizza dough.
Essential practices to prevent risks in the home
In France, to prevent foods from becoming contaminated by this bacterium, food industry professionals must apply good hygiene practices and monitoring measures at the production stage, before products are placed on the market.
When preparing meals, consumers can also prevent the risks associated with certain foods by observing the following hygiene and consumption rules:
- Wash hands with soap after going to the toilet, before preparing and eating meals, and after handling foods, whether or not they are raw;
- Wash vegetables, fruit and herbs thoroughly, especially those that will be consumed raw; also peel fruit and vegetables if possible;
- For foods that are meant to be consumed cooked, do not eat them if they are raw or undercooked.
Moreover, for more susceptible population groups such as children, the elderly, and immunocompromised individuals, it is advisable to:
- Cook minced meat and minced-meat products thoroughly (internal temperature of 70°C);
- Avoid the consumption of raw milk and raw-milk products (except for hard pressed cheeses);
- Avoid consuming raw or undercooked products made with flour (cookie dough, etc.).
Updating the classification of pathogenic E. coli strains
In France, the monitoring of EHEC in food is based on the ANSES classification proposed in 2017, taking into account data on HUS in children. It specifies the strains most associated with serious forms of infection. More recently, the Agency analysed the latest data on cases of HUS in both children and adults. It used its findings to propose a new four-group classification of strains based on their virulence potential, i.e. their ability to induce serious clinical forms such as HUS and bloody diarrhoea. This classification will enable the Directorate General for Food (DGAL) to update the monitoring criteria to be applied in food processing sectors.
Broadening monitoring to include new food sectors
During epidemiological investigations into isolated cases of infection, the sources of contamination are seldom identified. And yet, an analysis of recent outbreaks in France and abroad has identified new sources of contamination other than beefburgers and raw-milk cheeses, including the flour used in industrial pizza dough. Therefore, ANSES recommends that other animal- and plant-based foods should be subject to microbiological monitoring, including official controls and own checks.