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Update on local measles activity and testing

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Advisory Alert

To: Local Health System Partners

October 2, 2025

Background

Localized transmission of measles was identified in the Public Health Sudbury & Districts service area in July 2025. Since August 14, 2025, no additional cases or onward transmission have been detected.

However, measles continues to circulate in Ontario and around the world. Consider measles in the differential diagnosis of patients with rash or respiratory symptoms like runny nose and cough, particularly in individuals with recent travel to higher-risk areas or locations with known exposures. If you suspect or are testing for measles, contact Public Health immediately.

Testing guidance

Ontario testing guidelines have changed. A revised sample requisition has been included at the bottom of this Advisory Alert for reference.

Resources

Sincerely,

Original Signed By

Dr. Emily Groot, MD, MPH, FRCPC
Acting Associate Medical Officer of Health

Note: All Advisory Alerts are found on our website.

Image of a Public Health Ontario general test requisition form, with required sections for measles testing highlighted. These include, 1) adding ‘Suspect measles case’ and ‘STAT’ at the top of the form, preferably in red, 2) in the specimen collection section of the form, a throat or nasopharyngeal swab and urine should be ordered, 3) the test(s) requested section must be filled in, and each specimen requires its own lab requisition, 4) in testing criteria/indication section, ‘diagnosis’ must be selected and specify ‘suspect measles case’, 5) signs and symptoms section must be completed with date on symptom onset included for each symptom, 6) relevant exposure(s) section must be completed, and 7) relevant travel(s) section must be completed.

This item was last modified on October 3, 2025