Locally-acquired cyclosporiasis in Ontario

Advisory Alert

August 13, 2019

* Cette information est seulement disponible en anglais.

To community health care providers:

Re: Locally-acquired cyclosporiasis in Ontario

I am writing to advise you that Ontario is experiencing an increase in the number of Cyclospora infections. There have been 113 locally-acquired cyclosporiasis cases reported in the province between April 1 and August 6, 2019. We are requesting your assistance with the diagnosis of infected patients. Testing for Cyclospora will support prompt treatment of patients to lessen the duration of symptoms, as well as assist with identifying the source of illness.

Etiology and Clinical Presentation

Cyclosporiasis is a gastrointestinal illness caused by infection with the parasite Cyclospora cayetanensis. It is commonly characterized by frequent watery diarrhea, as well as other symptoms such as anorexia, fatigue, abdominal cramps, nausea, and myalgia. Left untreated, symptoms typically last 6 to 7 weeks and can wax and wane in intensity. Symptoms generally improve within 2 to 3 days of starting the first-line treatment for cyclosporiasis.

Causes and Risk Factors

People are infected by ingesting food or water contaminated with the parasite. Cyclospora is not endemic in Canada. Most reported cases in Ontario are infected when visiting an endemic country (for example, in the Caribbean, South and Central America, South and South East Asia) or during annual spring/summer outbreaks of cyclosporiasis. When cases occur in individuals who did not travel (as is currently occurring in Ontario), an investigation is launched to determine potential sources of Cyclospora in imported foods. Most outbreaks of locally-acquired infections are likely due to fresh produce such as berries or herbs that are imported from Cyclospora endemic countries. The infection is unlikely to spread from person to person.

Diagnosis and Laboratory Testing

Cyclospora infection can be diagnosed by submitting a stool sample for ova and parasite testing to the Public Health Ontario Laboratory. If patients present with cyclosporiasis-compatible symptoms, please request testing for stool parasites on the Public Health Ontario Laboratory General Test Requisition form and specify the request is to test for Cyclospora.

The Public Health Ontario General Test Requisition can be found at: https://www.publichealthontario.ca/-/media/documents/lab/general-test-requisition.pdf?la=en

More information on testing may be found here: https://www.publichealthontario.ca/en/laboratory-services/test-information-index/cyclospora-faeces


First-line treatment is trimethoprim-sulfamethoxazole (TMP-SMX). Symptoms typically improve within two to three days of starting TMP-SMX. Additional treatment information may be found here: https://www.cdc.gov/parasites/cyclosporiasis/resources/pdf/cyclosporiasis_provider.pdf


Report any suspected cyclosporiasis cases immediately to Public Health Sudbury & Districts for follow-up.

Should you have any questions, please contact the Environmental Health Division at 705.522.9200, ext. 464.


Ariella Zbar, MD, CCFP, MPH, MBA, FRCPC
Associate Medical Officer of Health

Additional Resources on Cyclosporiasis

For more details on Cyclospora infection, see: https://www.canada.ca/en/public-health/services/diseases/cyclosporiasis-cyclospora/health-professionals-cyclosporiasis-cyclospora.html

For more information on cyclosporiasis in Ontario, including links to testing information, see: http://www.publichealthontario.ca/en/BrowseByTopic/InfectiousDiseases/Pages/IDLandingPages/Cyclosporiasis.aspx

This item was last modified on August 14, 2019