Public health officials in four provinces are trying to track an outbreak of the intestinal illness cyclosporiasis.
A total of 51 cases of locally-acquired Cyclospora have been reported across Canada since May, with 44 in Ontario, four in Quebec, two in Alberta and one in British Columbia.
A source of the outbreak has not been identified but the Canadian Food Inspection Agency and health officials say they are eyeing imported fresh produce.
Previous outbreaks have been linked to imported fresh, pre-packaged salad mixes, basil, cilantro, raspberries, blackberries, mesclun lettuce and peas.
The Cyclospora parasite is common in Mexico, Cuba, Dominican Republic, Guatemala, Peru, India and Southeast Asia.
It is passed in human feces and spread through contaminated food or water, and can cause everything from diarrhea and abdominal bloating to mild fever, nausea and weight loss.
A release from the Public Health Agency of Canada says some people report no symptoms while others describe it as similar to a bad case of stomach flu.
The agency says most people recover fully, although it may take several weeks before intestinal problems completely disappear, and anyone who suspects cyclosporiasis should contact their doctor.
Washing does not always remove the parasite, but health officials say risks can be reduced by cooking produce imported from countries where Cyclospora is found and by consuming fresh produce from Canada, the United States or Europe, where the bug is not common.