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:
Updates:
- Updated test frequency and location to include other testing sites at PHO’s laboratory.
- Updated the Submission and Collection Notes section to indicate that urine submission is recommended to improve the sensitivity of testing.
- As of 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.
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.
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 Requirements
| Test Requested | Required Requisition(s) | Specimen Type | Minimum Volume | Collection Kit |
Measles Virus Diagnosis |
Nasopharyngeal swab3,4 |
1 swab in transport media contained in kit |
Virus Respiratory Kit order#: 390082 |
|
Measles Virus Diagnosis |
Throat swab3,5 |
1 swab in transport media contained in kit |
Virus Culture Kit order#: 390081 |
|
Measles Virus Diagnosis |
Urine3,6 |
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.
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 |
Monday to Saturday |
11AM |
|
Measles PCR |
Up to 3 business days from receipt at PHO Laboratory |
Hamilton |
Monday to Friday |
11AMa |
|
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 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 at 416-235-6556/1-877-604-4567 or after-hours, contact the Duty Officer at 416-605-3113 for consultation.
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.
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