Yersiniosis is a disease caused by bacteria belonging to the family Yersinia. Symptoms of yersiniosis can vary 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, right-sided abdominal pain and fever may be the predominant symptoms and may be confused with appendicitis. Rarely, complications such as skin rash, joint pains, or spread of bacteria to the bloodstream can occur. Yersiniosis is spread by consuming contaminated food, especially raw or undercooked pork products, drinking unpasteurized milk or untreated water, or contact with infected animals. For more information, see the health unit’s fact sheet on yersiniosis.
Simcoe Muskoka
Ontario
Technical Notes
Simcoe Muskoka
The following graph shows the number of yersiniosis cases in Simcoe Muskoka between 2000 and 2021. There have been between zero and 19 cases of yersiniosis in Simcoe Muskoka every year since 2000. In 2021, 13 cases of yersiniosis were reported in Simcoe Muskoka. A review of the cases in 2017 did not show any common exposures or risks to which the increase of cases could be attributed.

Ontario
The following graph shows the incidence rate of yersiniosis in Simcoe Muskoka and Ontario between 2000 and 2021. The Ontario incidence rate has decreased in this time period. In 2021, the Simcoe Muskoka incidence rate was 2.1 cases per 100,000 population and the Ontario rate was 1.6 cases per 100,000 population.

More detailed data for Ontario and each health unit can be found on Public Health Ontario’s interactive Reportable Disease Trends in Ontario tool.
Technical Notes
There are many factors that influence how many cases are reported to the health unit, as explained on the Infectious Diseases page. It is unclear to what extent the global COVID-19 pandemic has influenced the reporting and spread of other infectious diseases – counts and rates of disease since 2020 should be interpreted with caution.
Provincial definitions classify cases as confirmed or probable based on clinical and/or laboratory diagnostic criteria. The provincial case definition for yersiniosis changed in April 2009 to include a definition for probable cases whereas before there was no such classification. The definitions of confirmed and probable cases from 2009 onwards are comparable to confirmed cases before 2009.
Page last updated August 19, 2022