Yersiniosis is an infection of the gastrointestinal system caused by a bacterium of the genus Yersinia. Within this genus, there are three known species, namely Yersinia pestis, Yersinia pseudotuberculosis and Yersinia enterocolitica. The most commonly occurring cause of yersiniosis in Belgium is Y. enterocolitica.

Y. enterocolitica and Y. pseudotuberculosis are bacteria that are widespread in the environment and for which food is considered the main source of infection. Strains potentially pathogenic for humans can be found in pigs for Y. enterocolitica as well as in several animal species for Y. pseudotuberculosis.

Y. pestis is the causative agent of plague is and is transmitted by fleas from, among others, rats to humans. This disease is not discussed in this health topic.

Symptoms of yersiniosis appear 3 to 7 days after infection:

• fever
• diarrhoea (with or without blood)
• abdominal pain (sometimes reminiscent of appendicitis)
• headache
• in more severe cases, nausea, vomiting and emaciation may also occur.

After several weeks, other symptoms may also appear (most of which are rather rare), such as:

• joint problems
• eye infection
• skin condition with swelling (Erythema nodosum)
• inflammation of other organs such as kidney, pancreas, thyroid, lymph nodes and heart muscle
• blood poisoning.

The main causes of yersiniosis are eating raw or inadequately cooked food and poor hygiene. The latter applies, on the one hand, to insufficient hygienic measures in the kitchen during food preparation, such as, for example, using the same chopping board and knives for meat and raw vegetables. On the other hand, the bacterium can also be transmitted through inter-human infection via the fecal-oral route (example: an infected person prepares food without first washing the hands after going to the toilet).

Yersinia can also be transmitted through contaminated water or milk.

Yersinia is a bacterium that is transmitted primarily by the oral route through food.

To prevent transmission, hygiene regulations must be strictly followed, especially when preparing, cooking and storing food.

• Wash and clean:
  • wash your hands after going to the toilet
  • wash your hands before cooking
  • wash your hands after handling high-risk foods (raw meat)
  • clean the work surface on which the high-risk food was prepared and the utensils used to prepare it
  • clean the refrigerator regularly (once a month).
• Cook in a proper manner: cook meat (pork in this case) well (at least 65°C for 5 to 6 minutes).
• Store as cool as possible:
  • place food (pork) in the refrigerator (4°C) as soon as possible after purchase)
  • defrost food in the refrigerator or microwave (not at room temperature).
• Keep raw food separate from prepared food:
  • use a different chopping board for cutting meat
  • use a different knife for cutting meat
  • keep raw meat separate from other food, in your shopping bag and in the refrigerator, in order to avoid cross-contamination.

The doctor takes a sample of the patient’s stool and sends it to a laboratory for culture (coproculture).

When symptoms such as joint problems appear after several weeks and the symptoms of diarrhoea have passed, the diagnosis is made via a blood test instead of a stool culture. If positive, the laboratory sends the human bacterial strain to the National Reference Centre for Yersinia at Sciensano’s Bacterial Diseases Unit.

Anyone can get yersiniosis, but in some frail or weak people, the disease can worsen due to dehydration, intestinal disorders and, in severe cases, blood poisoning (sepsis). These are:

• young children
• the elderly
• immunodepressed people.

Yersiniosis is usually a benign disease requiring no special treatment. However, proper care must be taken to take in sufficient fluids by drinking plenty of water. With a more severe course or persistent symptoms, the disease is treated with antibiotics. Additional treatment may also be chosen for joint problems.