Confirmed case of measles in Ottawa

To: Ottawa Physicians and Nurse Practitioners
Date: August 14, 2025
From: Dr. Michelle Foote, Associate Medical Officer of Health
Subject: Confirmed case of measles in Ottawa

Dear Colleagues,

A case of measles has been reported to Ottawa Public Health with potential exposures to the virus for others in the community. Secondary cases from these exposures could occur any time until 21 days following each exposure.

OPH is following up individually with all identified contacts and has issued a Public Service Announcement (PSA) to notify of exposures where individual persons cannot be identified. Contacts from some of the exposures in the PSA are outside the time period where post-exposure prophylaxis can be expected to prevent infection. Individuals are therefore advised to:

• Review their vaccination record to ensure they are protected against future exposures;
• Monitor for symptoms of measles and seek medical attention if symptoms develop;
• Call ahead to the health care facility/practice and tell their health care provider that they have recently been exposed to measles;
• Defer any non-urgent medical appointments until after 21 days from their exposure to measles.

Measles is considered contagious from 4 days before rash onset (or 1 day before symptom onset if no rash is present) to 4 days after rash onset. The measles incubation period (from exposure to rash onset) ranges from 7 to 21 days. OPH’s webpage on measles for health care providers has information on the assessment, testing, and management of suspect measles cases, and the Public Health Alert posted on June 12th, 2025, Update - Measles Outbreak Preparedness and Response, also has details on the clinical presentation, assessment, testing, and management of those suspected of having measles.

Please also see a recently developed fact sheet from Public Health Ontario intended as a quick reference guide for clinicians: How to Recognize and Respond to Measles.

Report suspected cases immediately to Ottawa Public Health

Please notify OPH at 613-580-6744 from Monday to Friday 8:30 am to 4:30 pm or dial 3-1-1 after hours and ask for Public Health On-Call. Reporting a suspected measles case should not be delayed pending lab results.

Revised (August 19, 2025): This Public Health Alert was updated to include a new resource from Public Health Ontario.