Salmonellosis is a very common foodborne infection. By following certain hygiene rules, in particular during the preparation, cooking and storage of foodstuffs, salmonellosis can be prevented.

How is salmonellosis transmitted?

The principal causes of salmonellosis are badly cooked food, poor hygiene and incorrect storage of foodstuffs.

The Salmonella bacteria is transmitted to humans orally:

  • mainly by ingesting foodstuffs that come from contaminated animals which are consumed raw or undercooked (meat, eggs, raw egg products)
  • sometimes by ingesting food soiled with excrement from a contaminated animal (fruit, vegetables, salads)
  • indirectly by ingesting clean food that has been contaminated by contaminated food or water.

More rarely, salmonellosis can also be transmitted:

  • by interhuman contamination through the faecal-oral route (for example: an infected person preparing food without having washed their hands after going to the toilet)
  • by direct or indirect contact with a contaminated animal (domestic animals or pets e.g.: pet reptiles).

Salmonellosis arises more frequently in summer, during the party and barbecue season when foods are kept at ambient temperature for a long time, which promotes the development of bacteria.

Where are Salmonella bacteria found?

Most Salmonella are found in the gut of wild animals and pets:

  • animals intended for human consumption (poultry, pork, cattle)
  • pets (dogs, cats), birds, rodents and reptiles (tortoises, etc.)

Animals can be “healthy carriers” of the bacterium. They are contaminated by the Salmonella bacteria but are not ill.

Mechanisms of transmission

Salmonella is a bacterium that is omnipresent and resistant, that can survive for a number of weeks in a dry in environment and for a number of months in water.

Salmonella invades the cells of the intestinal mucosa and leads to acute inflammation which causes diarrhoea.

In some people who are more fragile or have a weakened immune system bacteria can break through the intestinal wall and spread to the blood, causing septicaemia and infecting other organs such as the brain in the case of meningitis.

Typhoid fever

The Salmonella bacteria that are responsible for typhoid and paratyphoid fevers are only found in humans.

The bacteria is transmitted by ingesting water or food contaminated by infected faecal matter of human origin.

The main cause of the oral-faecal transmission of diseases is a lack of hygiene and a lack of drinking water.


Sciensano helps to diagnose cases of salmonellosis, identifies the sources of contamination, checks products, monitors the evolution of salmonellosis in Belgium and studies Salmonella bacteria's susceptibility to antibiotics.



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