What is Yersiniosis?

Yersiniosis (yer-sin-ee-o-sis) is a disease caused by bacteria called Yersinia. Although many species of Yersinia are found worldwide, most human illnesses are caused by Yersinia enterocolitica. Other species of Yersinia affecting humans are Y. pseudotuberculosis, which causes an illness similar to Y. enterocolitica,and Y. pestis which causes plague. Yersinia are hardy bacteria that can survive in adverse conditions like refrigeration and environments low in oxygen.

The most common source of Y. enterocolitica infection in humans is pork (raw or undercooked) and pigs are considered the main carrier. Other strains of Yersinia are also found in many other animals including rodents, rabbits, sheep, cattle, horses, dogs and cats.


What are the symptoms of Yersiniosis?

Persons infected with Yersinia can have a variety of symptoms depending on the age of the person infected. Common symptoms in children are fever, abdominal pain and diarrhea (which is often bloody).  In older children and adults, the most common symptoms are right-sided abdominal pain, and fever. Complications such as skin rash, joint pains or spread of bacteria to the blood stream can occur in a small number of cases.

Symptoms of yersiniosis generally begin 3 to 7 days (usually under 10 days) after a person becomes infected and last approximately one to three weeks, although symptoms may last longer in some cases. Yersinosis is more common in children during the winter months.


How is Yersiniosis spread?

Yersiniosis is usually associated with eating or drinking food or water contaminated with Yersinia bacteria, or by contact with a person or animal infected with Yersinia bacteria.

Yersinia bacteria live in the intestines of infected persons/animals and are released with bowel movements. Raw meat of infected animals can become contaminated during slaughtering. If good hand hygiene (e.g. with soap and water for at least 15 seconds) is not practiced after using the toilet or handling raw meat, a person with Yersinia bacteria can transfer the bacteria to food and objects. An infant or child can be infected if a parent or caretaker handles contaminated food and does not wash his/her hands adequately before handling the infant or child and their food, bottles, pacifiers or toys.


You can also become infected by:

  • Eating contaminated food, especially raw or undercooked pork products.
  • Drinking contaminated drinking or recreational (e.g. swimming in a lake) water.
  • Drinking contaminated unpasteurized milk or unpasteurized milk products.
  • Putting something in your mouth that has come into contact with the droppings of infected animals or stool of infected humans.
  • Children can become infected if they put their hand in their mouth after or during playing with infected puppies and kittens.


How is Yersiniosis diagnosed?

Yersiniosis is usually diagnosed by detecting the Yersinia bacteria in the stool. The organism can also be detected in other body sites, including the throat, lymph nodes, urine, bile and blood.


How can you prevent Yersiniosis?

The most important preventive measure is good hand washing.  Wash your hands with soap and water for at least 15 seconds:

  • before eating and handling food
  • after touching raw meat
  • after using the toilet
  • after assisting others with the toilet
  • after changing diapers
  • after contact with animals or after visiting a petting zoo.



  • Cook all meat thoroughly.
  • Consume only milk or milk products that have been pasteurized.
  • Handle food safely.  Use separate cutting boards for raw meat and ready to eat food. Clean and sanitize all cutting boards, countertops and utensils after preparing raw meat.
  • Protect drinking and recreational water supplies from animal and human feces.
  • Avoid drinking water from springs, rivers, lakes or streams. Only drink water that you know is uncontaminated. If you are not sure, treat the water yourself.  For example, boil the water for at least five minutes.


This page provides basic information only. It must not take the place of medical advice, diagnosis or treatment. Always talk to a health care professional about any health concerns.

Source:  Ontario Ministry of Health and Long-Term Care, Public Health Division.


For Further Information

Call the Infectious Disease Program: (807) 625-5900

or toll-free 1-888-294-6630

Health Topic
Diseases & Infections