Molecular Detection (RT-PCR)

Molecular detection of the measles virus by RT-PCR.

• Measles
• Subacute sclerosing panencephalitis (SSPE)

Urine, nasopharyngeal (NP) swab, throat swab. All specimens should be collected as soon as possible after rash onset (within 7 days). Note: specimens collected later will still be accepted however the assay sensitivity will not be optimal. Viral isolates may also be sent.

Collect 50 mL (minimum 10 mL) of urine in sterile container. For swabs, use sterile swabs approved for virus isolation to swab the throat or nasal passages to collect epithelial cells. Place NP and throat swabs in 2-3 mL viral transport medium (VTM) for a minimum of 1 hour. For viral isolate, collect infected cells and media and submit 1.0 mL.

Process urine by centrifuging at 500 x g for 10 minutes, preferably at 4°C. Resuspend the sediment in 2 mL of VTM. For NP and throat swabs, remove the swab. Store all specimens at 4°C and ship on wet ice for arrival at the NML within 48 hours of collection. Otherwise, freeze at -70°C and ship frozen on dry ice. Do not freeze unprocessed urine. Viral isolates should be shipped frozen (-70°C) on dry ice.

Shipping of specimens shall be done by a TDG certified individual in accordance with TDG regulations. For additional information regarding classification of specimens for the purposes of shipping, consult either Part 2 Appendix 3 of the TDG Regulations or section 3.6.2 of the IATA Dangerous Goods Regulations as applicable.

Suspected cases of measles. Refer to reference 1 for case definitions. For cases with recent vaccination, 1 year of age and/or identified as suspected post-vaccine reactions, an additional RT-qPCR specifically targeting the vaccine virus will be performed.

Completed Measles, Mumps, and Rubella requisition form. Include date of rash onset, date of last measles vaccination (if recent), travel history and/or MARS identifier (from the Measles and Rubella Surveillance application on CNPHI) or case number as available. For suspected post-vaccine reactions, provide the vaccination date and select “Genotyping – measles vaccine suspected” on the requisition.

Measles genotyping is automatically performed on measles RT-PCR positive samples. Labs that perform their own measles RT-PCR testing should submit to the NML all positive samples for surveillance and reporting to the World Health Organisation. It is important to provide a complete patient history (including travel) for accurate genotype surveillance.  The NML is a WHO/PAHO accredited Measles and Rubella Regional Reference Laboratory.

Extracted RNA from samples is tested by real-time RT-PCR for the measles nucleoprotein gene and measles hemagglutinin gene (general RT-PCR) (2). Positive RT-PCR result is laboratory confirmation of measles infection, of any genotype. For suspected post-vaccine reactions, an additional RT-PCR specifically targeting the vaccine virus (genotype A) is used for rapid typing (MeVA) (3). Positive MeVA result confirms presence of vaccine virus. Negative MeVA result, with a positive general RT-PCR, is consistent with non-vaccine and genotyping is performed.

7 calendar days. Stat testing available upon request.

1. Measles and Rubella Elimination Working Group, Health Canada, Public Health Agency of Canada. Guidelines for the prevention and control of measles outbreaks in Canada. CCDR. 2013; 39:ACS-3. Available at http://www.phac-aspc.gc.ca/publicat/ccdr-rmtc/13vol39/acs-dcc-3/index-eng.php#appa.
2. Zubach V, Severini A, Hiebert J. Development of a rapid, internally controlled, two target, real-time RT-PCR for detection of measles virus. J Virol Methods. 2022 Jan;299:114349. doi: 10.1016/j.jviromet.2021.114349. Epub 2021 Nov 2. PMID: 34740707.
3. Roy F, Mendoza L, Hiebert J, McNall R, Bankamp B, Connolly S, Lüdde A, Friedrich N, Mankertz A, Rota P, Severini A. Rapid identification of measles virus vaccine genotypes by real time PCR. J Clin Microbiol. 2017 Mar;55(3):735-743.
4. WHO. Manual for the Laboratory-based Surveillance of Measles, Rubella, and Congenital Rubella Syndrome. Third edition, June 2018. Available at https://www.technet-21.org/en/topics/laboratory-measles-rubella-manual

Pathogen Safety Data Sheets: Infectious Substances – Measles virus

For health professionals: Measles

National case definition: Measles

Measles: Symptoms and treatment

Measles and Rubella Weekly Monitoring Reports