Escherichia Coli

Enterohaemorrhagic E. coli (EHEC) infection and how you can prevent it

Escherichia coli (E. coli) is a bacterium found naturally in the digestive microflora of humans and warm-blooded animals. While most Escherichia coli strains are safe for humans, certain strains such as enterohaemorrhagic E. coli (EHEC) cause potentially severe infections, primarily in young children and the elderly.

Principal sources of contamination

The main reservoirs of these bacteria are cattle and sheep, which are often asymptomatic carriers whose faeces can contaminate the environment.

These bacteria are primarily transmitted through food. Foods of animal origin can become contaminated at the slaughterhouse for meat, during the skinning and evisceration of animals, or on dairy farms during milking.

For plants, this contamination can occur when manure or ruminant farm effluents are spread on the soil where the plants are grown, or when contaminated irrigation water is used. 

Drinking water can be contaminated either accidentally or due to inadequate treatment.

Lastly, contamination can occur during food preparation, when the person preparing the meal does not wash their hands properly. 

Direct transmission is possible through contact with carrier animals or their faeces, as well as from person to person.

Main foods involved

The main foods involved in EHEC outbreaks around the world are undercooked minced beef, unpasteurised dairy products, fresh produce (lettuce, young white radish sprouts, sprouted seeds), unpasteurised fruit and vegetable juices, and inadequately treated drinking water. Flour can also be contaminated: there have recently been outbreaks caused by the consumption of raw or undercooked dough or batter. 

Health impacts

In humans, EHEC is responsible for a variety of disorders, ranging from mild diarrhoea to more severe forms, including haemorrhagic diarrhoea and/or severe kidney disease in the form of haemolytic uremic syndrome (HUS), primarily in young children. Adults can develop thrombotic microangiopathy (TMA).

The most at-risk population groups

The population groups that are more likely than average to develop severe forms or symptoms of infection are children under the age of 15 (especially those under five) and the elderly

How to limit your exposure as consumers

  • 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, fruits and herbs thoroughly, especially those that will be consumed raw. Peel vegetables if possible;
  • for foods that are meant to be consumed cooked, do not eat them if they are raw or undercooked.

For susceptible population groups:

  • 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.

ANSES’s role

  • research mission:  ANSES develops molecular biology methods to rapidly detect bacteria in food that are potentially dangerous to humans;
  • assessment mission: ANSES undertakes risk assessments throughout the food chain and issues recommendations intended for professionals, the public authorities, and consumers.