Salmonellosis and how you can prevent it

Infections by Salmonella bacteria are the second most common cause of foodborne illnesses in Europe. Salmonella infections cause occasionally acute gastroenteritis, but can be more severe in certain susceptible populations. This article provides an overview of the disease and the ways to prevent it.

Salmonellosis in figures

In 2019, Salmonella was responsible for 39% of confirmed foodborne illness outbreaks in France.

In Europe, infections by Salmonella bacteria are the second most common cause of foodborne illnesses. However, the number of outbreaks where these bacteria have been isolated has been steadily decreasing in the European Union since 2001. This improvement reflects the effectiveness of Europe’s food safety policy for farms and slaughterhouses, with the systematic culling of contaminated flocks of laying hens and hygiene measures throughout the production chain.

Principal sources of contamination

Animals, including farm animals, are often asymptomatic carriers of the bacterium and do not become ill. Animal dung can transmit the bacterium to water, plants and other animals through contact. Animal-based foods can therefore be infected, and contaminate environments such as kitchens, preparation and production facilities, as well as the people who handle such foods, including cooks.

The foods most likely to be contaminated

Raw or undercooked foods, especially of animal origin, are most likely to be contaminated, for example, raw eggs and products made from raw eggs, meat including beef, pork, poultry and uncooked delicatessen meat products, and raw milk cheeses.

Other sources of contamination include fresh produce, powdered infant formula, dried fruit, chocolate and cereals.

Almost half of all Salmonella foodborne illness outbreaks are associated with eggs and foods made from raw eggs, such as mayonnaise, custard desserts, chocolate mousse and tiramisu.

Health impacts

Salmonella can cause acute gastroenteritis, which usually resolves spontaneously within a few days.

However, the effects can be severe in particularly susceptible individuals, such as:

  • people suffering from malnutrition ;
  • people with achlorhydria, hypochlorhydria or a neoplastic disease, or receiving treatment for acid reflux ;
  • people receiving a broad-spectrum antibiotic treatment.

In infants and people who are immunocompromised (e.g. individuals who have an autoimmune disease, an immunosuppressive disorder or who are taking medicine to suppress the immune system), Salmonella infections can become very serious and even fatal.

How to limit our exposure as consumers

  • hands should be washed with soap after going to the toilet, before preparing and eating meals, and after handling foods, whether or not they are raw ;
  • eggs should be stored at a constant temperature, either by keeping them refrigerated or at room temperature, and should never be washed before storage, as washing them may cause micro-organisms on the shell to migrate inside ;
  • food containing raw eggs should be consumed quickly after preparation, or kept refrigerated and consumed within 24 hours ;
  • animal-based foods should be cooked thoroughly (to reach 70°C in the centre), in particular pork and poultry, and minced meat.
  • people at risk are advised not to eat raw or undercooked eggs.

ANSES’s role

  • collecting data on contaminated animals and foods, as well as farms, slaughterhouses and food preparation plants, as part of the government’s surveillance programme and ANSES’s national reference mandate for this family of bacteria ;
  • identifying the different strains and analysing the trends depending on the source of the samples through the national Salmonella network managed by ANSES. This network collects strains associated with Salmonella isolated from animal, food and environmental sources ;
  • participating in the investigation of outbreaks of human salmonellosis in conjunction with the Directorate General for Food, Santé publique France and the National Reference Centre for Escherichia coli, Shigella and Salmonella (ESS).

Conducting risk assessments throughout the food chain and identifying the most effective measures to reduce the risk of salmonellosis.