Cases of Measles in Ottawa

To: Ottawa Physicians and Nurse Practitioners
Date: May 1, 2025
From: Dr. Michelle Foote, Associate Medical Officer of Health
Subject: Cases of Measles in Ottawa

Dear Colleagues,

Two cases of international travel-related measles have been reported to Ottawa Public Health (OPH). Consequently, other persons may have been exposed to measles in Ottawa, and details of these exposures can be found in the Public Service Announcement. 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 all exposures in the PSA are outside the time period where post-exposure prophylaxis can be expected to prevent infection. They 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.

Measles is considered contagious from 1 day before symptom onset (or 4 days before rash onset, whichever is longer) 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 of suspect measles cases, and the Public Health Alert posted on February 12^th, Measles Update and Resources for Health Care Providers, has additional details on the clinical presentation, assessment, testing, and management of those suspected of having measles.

Persons who have been exposed to measles or where there is a concern of measles should ideally be seen at the end of the day, masked, and immediately placed in a separate room that must be kept empty for 2 hours after the visit. All health care workers, including non-clinical and office staff, should have documented immunity to measles (2 doses of measles vaccine or anti-measles IgG antibody).

Ensure suspect cases are promptly placed under airborne precautions.

If additional assessment is required, contact the facility before sending the patient. To minimize exposure, DO NOT send a child you suspect has measles to any health care facility without prior notification.

Report suspect cases immediately to Ottawa Public Health

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 suspect measles case, should not be delayed pending lab results.

Testing of suspect cases

Obtain samples for STAT testing:

1. A nasopharyngeal or throat swab for measles PCR, AND
2. Urine (50mL) for measles PCR

Diagnostic serology (measles IgM and IgG) can be considered but is not required. Collection of samples for PCR testing is the most important component for diagnosing measles. If considering serology, exposures can be reduced by collecting blood at the time of the clinic visit (avoid sending patients to a community or hospital lab for serology) and using appropriate IPAC measures.

Please notify Ottawa Public Health prior to testing and sending specimens as we may be able to support the testing process and expediate timely processing. If proceeding with testing, the following is required:

• Send all measles specimens directly to the PHO lab
• Clearly mark specimens ‘STAT’ and separate from other routine specimens
• Notify the PHO lab when the specimens are ready to be shipped
• PCR testing cut-off is before 11 a.m. to ensure results are reported on the same day

Patients with suspected measles should not be directed to a hospital emergency department or hospital laboratory for any measles work-up, including serologies. The CHEO Infectious Diseases team is available for referrals for pediatric patients needing clinical evaluation (not testing alone) and to discuss whether testing is indicated for a more complex patient situation where exposure history and/or signs and symptoms do not clearly indicate testing. Providers wishing to consult with the CHEO Infectious Diseases team should call 613-737-7600 x0 and ask for the Infectious Diseases physician on call.

Laboratory requisition form must include the following:

• Ordering physician or health care professional's name and telephone number
• Testing indications (i.e., “Diagnosis”) and Other (specify): “Suspect case of measles”
• Specifying type of specimen (e.g. throat swab, nasopharyngeal swab, urine, serology)
• Ordering serology, mark as “Measles IgG and IgM - Diagnosis"
• Immunization history, exposure history, and travel history outside Ottawa for 21 days prior to start of symptoms
• Relevant signs, symptoms, and/or clinical history, and onset date
• Reason for testing (diagnostic)

Please see Ottawa Public Health’s webpage on measles for health care providers for information on measles vaccine eligibility and other resources.