What is Yersiniosis?

Yersiniosis (yer-sin-ee-o-sis) is an infection caused by the bacteria Yersinia. Yersinia is a strong bacteria that can continue to live in environments without much oxygen and in refrigeration.

One common source of infection can be contaminated food such as raw or undercooked pork. Some strains of Yersinia are found in many other animals including rodents, rabbits, sheep, cattle, horses, dogs and cats. Yersiniosis often looks like appendicitis, but it is not. 

What are the signs and symptoms?

The signs and symptoms of Yersiniosis often appear within 10 days after exposure and include:

  • Watery diarrhea (sometimes bloody)
  • Cramps
  • Fever
  • Abdominal pain (often right-sided)
  • Nausea and vomiting

How is it spread?

Yersiniosis is usually spread:

  • eating contaminated food, especially raw or undercooked pork products
  • ingesting contaminated drinking or recreational water
  • consuming contaminated unpasteurized milk or unpasteurized milk products, or
  • 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 and treated?

Yersiniosis is usually diagnosed by looking for the Yersinia bacteria in a stool sample (poop sample).

Most people who have healthy immune systems will recover without treatment. Treatment of yersiniosis usually involves treating the symptoms only. For example, persons with diarrhea should generally drink lots of liquids to avoid dehydration. More severe or complicated cases may require antibiotics. 

How long is it contagious?

Yersiniosis is contagious:

  • As long as bacteria are in the stool.
  • If left untreated for 2 to 3 months.

How can you prevent yersiniosis?

  • The most important preventive measure is good hand hygiene. Practice good hand hygiene. Wash your hands with soap and water:
  • before eating and handling food
  • after touching raw meat
  • after handling raw pork/chitterlings
  • after using the toilet
  • after assisting others with the toilet
  • after changing diapers
  • after caring for a person who has diarrhea
  • after contact with animals (if your dog or cat has diarrhea, wash your hands frequently as you care for it), and
  • after visiting a petting zoo (wash children's hands 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 shallow wells, rivers, lakes or streams. Only drink water that you know is uncontaminated. If you are not sure, treat the water yourself, for example, by boiling for at least five minutes.

Health Care Providers

Yersiniosis is an infection that must be reported to the Medical Officer of Health. Laboratories are required to fax lab confirmed case information to the Health Unit by the next working day.  Fax to 226-783-2132.

To reduce the spread of further illness, symptomatic infected individuals should be excluded from handling food, providing patient care or working in daycares until symptom-free for 24 hours, or 48 hours after completion of antibiotics.  If you have any questions or concerns during or office hours, please call 519-258-2146 ext.1420 or after hours 519-973-4510.

Ontario’s Public Health Yersiniosis Infectious Disease Protocol / Management

Provincial Case Definition Yersiniosis


Heymann. D.L. "Control of Communicable Diseases Manual". 20th Edition. 2015. American Public Health Association: Washington D.C.

Ontario Ministry of Health and Long-Term Care Yersiniosis webpage

US Centres for Disease Control Yersiniosis webpage