Measles – Diagnostic – PCR

Consistent with O. Reg. 671/92 of the French Language Services Act, laboratory testing information on this page is only available in English because it is scientific or technical in nature and is for use only by qualified health care providers and not by members of the public.

This page provides diagnostic polymerase chain reaction (PCR) testing information for Measles at Public Health Ontario (PHO). For information regarding other testing options, including Cerebral Spinal Fluid (CSF) for Subacute sclerosing panencephalitis (SSPE) refer to:

Measles Serology TIS

Updates:

May 14, 2025: Updated recommendations for measles diagnostic testing during high measles transmission
May 9, 2025: Updated test frequency and location to include other testing sites at PHO’s laboratory.
April 25, 2025: Submitters are no longer required to contact PHO’s Laboratory Customer Service Centre or after-hours Duty-Officer for priority specimens notification. Submitters must package priority specimens for measles testing separate from routine specimens and mark “STAT” on the outside of the package.

*Uncontrolled print copy. Valid only on day of print: 21 May 2025.

Testing Indications

Measles PCR is a diagnostic test for the detection of viral RNA in clinical specimens collected from patients suspected of having Measles and is useful during the early phase of the disease following symptom onset.

Measles PCR is the preferred testing method during periods of significant community transmission such as the current multi-jurisdictional outbreak. Measles serology testing may provide additional diagnostic value, however blood collection may cause additional health care visit and community exposure and therefore is not mandated. The decision to collect blood for serology remains at the discretion of the health care provider.

Testing for immune status (IgG) is not routinely recommended for unvaccinated, under-vaccinated individuals, and unknown vaccination status. Measles-containing vaccine should be offered as the ideal protective measure in accordance with Canadian Immunization Guide.

For suspected cases of Measles, contact your local public health unit (PHU) prior to collecting specimens.

Acceptance/Rejection Criteria

Specimens received in incorrect containers or expired kits will be rejected.

Specimen Collection and Handling

Specimen Requirements

Test Requested	Required Requisition(s)	Specimen Type	Minimum Volume	Collection Kit
Measles Virus Diagnosis	General Test Requisition	Nasopharyngeal swab^3,4	1 swab in transport media contained in kit	Virus Respiratory Kit order#: 390082
Measles Virus Diagnosis	General Test Requisition	Throat swab^3,5	1 swab in transport media contained in kit	Virus Culture Kit order#: 390081
Measles Virus Diagnosis	General Test Requisition	Urine^3,6	Minimum volume 10mL	Sterile container

Submission and Collection Notes

Complete all fields of the requisition form, including:

Test(s) requests and indications for testing
Patient setting
Clinical information (symptom and symptom onset), MMR/MMRV vaccination status and travel history (including date of travel/return).

Label the specimen container(s) with the patient’s first and last name, date of collection, and one other unique identifier such as the patient’s date of birth or Health Card Number. For additional information see: Specimen Acceptance Criteria.

Failure to provide this information may result in rejection or testing delay.

For diagnosis of symptomatic patients, collect either a nasopharyngeal (NP) swab or throat swab for PCR testing, as well as a blood specimen for serology testing. Collecting a urine specimen along with an NP/throat swab may improve sensitivity of testing. See next section for the recommended timing of specimen collection.

Refer to the Nasopharyngeal Specimen Collection Instructions for collecting nasopharyngeal swab specimens.

Refer to the Throat Specimen Collection Instructions for collecting throat swab specimens.

Urine specimen collected in other media (i.e. CTNG specimen container) will be rejected for testing.

For submission of other specimen types please contact PHO’s Laboratory Customer Service Centre at 416-235-6556 or 1-877-604-4567.

Timing of Specimen Collection

Nasopharyngeal swab or aspirate and/or a throat swab should be collected within 7 days of rash onset.

Urine should be collected within 14 days of rash onset and submitted in a sterile container.

In certain situations, such as when there is a high index of suspicion for measles (e.g. compatible illness in a returned traveler or contact of a laboratory confirmed case), it may be warranted to test beyond the above time periods when specimens could not be collected earlier in the illness. This can be discussed with PHO’s laboratory on a case-by-case basis.

Testing of individuals exhibiting prodromal symptoms without a rash, who have a strong epidemiologic link to a confirmed case, is acceptable. Result should be interpreted with caution.

Storage and Transport

Place specimen in biohazard bag and seal. Specimens should be stored at 2-8°C following collection and shipped to PHO’s laboratory on ice packs.

All clinical specimens must be shipped in accordance to the Transportation of Dangerous Good Act.

Requisitions and Kit Ordering

Test Frequency and Turnaround Time (TAT)

Test	Turnaround Time	Test Location	Frequency	Sample receipt cut-offs*
Measles PCR	Up to 3 business days from receipt at PHO Laboratory	Toronto	Monday to Sunday	11AM
Measles PCR	Up to 3 business days from receipt at PHO Laboratory	Ottawa Kingston Timmins	Monday to Saturday	11AM
Measles PCR	Up to 3 business days from receipt at PHO Laboratory	Thunder Bay Hamilton London	Monday to Friday	11AM^a
Measles Vaccine Genotype PCR	Up to 3 business days after the confirmation of Measles PCR positive	Toronto	Monday to Saturday	N/A
Measles full Genotype (NML)	Up to 21 days from the receipt at NML	National Microbiology Laboratory	N/A	N/A

*Samples must arrive at PHO laboratory at time listed in this column to be included in the same day testing, samples that arrive later than time listed here will be tested on the next available run.

^aSamples received after 11am on Friday in London, Hamilton and Thunder Bay will be directed to Toronto for testing on Saturday.

STAT and Critical Specimens Testing

Priority testing is available outside of regular hours stated above in the “Frequency and turnaround time” section upon approval from PHO microbiologist. Contact PHO’s Laboratory Customer Service Centre at 416-235-6556/1-877-604-4567 or after-hours, contact the Duty Officer at 416-605-3113 for consultation.

Test Methods

Measles diagnosis is performed using polymerase chain reaction (PCR) – Laboratory developed test validated at PHO’s laboratory; not Health Canada approved.

Measles Vaccine Genotype is performed using polymerase chain reaction (PCR) – Laboratory developed test validated at PHO’s laboratory; not Health Canada approved.

Algorithm

Positive measles PCR will be tested first in-house with measles vaccine genotype PCR, all negative in-house measles vaccine genotype PCR will be referred to NML for full genotyping.

Due to the recent increase in measles cases, NML has implemented a triage and selection process for prioritizing measles genotyping based on:

Cases with no know epidemiological link (unknown source/acquisition)
Travel related cases
Hospitalized cases
First 5-10 cases in a new jurisdiction
Random sampling on a proportion of the submitted specimens linked to the current outbreak (Note, for specimens not selected as part of the sampling, NML will issue a cancellation report for genotyping result.)

Refer to NML for more information on measles genotyping - https://cnphi.canada.ca/gts/reference-diagnostic-test/4996?labId=1016.

Interpretation

Measles virus PCR:
Results will be reported as DETECTED/NOT DETECTED/INDETERMINATE.

An ‘indeterminate’ PCR test result may be due to a low level of target genetic material in the specimen, inadequate specimen content, or a non-specific signal. Please submit another specimen for testing if clinically indicated. This result must be interpreted within the context of the clinical history and epidemiological information.
A ‘not detected’ result does NOT exclude the possible presence of measles virus.

Measles vaccine genotype PCR:
Results will be reported as DETECTED/NOT DETECTED.

Not detected result indicates that the virus previously detected in this specimen by the measles PCR test is not the virus used in the measles vaccine.

Reporting

Results are reported to the physician, or authorized health care provider (General O. Reg 45/22, s.18) or submitter as indicated on the requisition.

Specimens that are positive for Measles are reported to the Medical Officer of Health as per Health Protection and Promotion Act.

Information for Health Care Providers

NOTE: Measles: Information for Health Care Providers

*Uncontrolled print copy. Valid only on day of print: 21 May 2025.

Contact Laboratory Customer Service

Microbiology and Laboratory Services

customerservicecentre@oahpp.ca

Updated 15 May 2025