Molecular Detection (RT-PCR)

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Accredited by the Standards Council of Canada to Laboratory no. 594 - CAN-P-4E (ISO/IEC 17025)

Requisition Forms

Reference Details

Description:

Molecular detection of the measles virus by RT-PCR.

 

Test Category:
Molecular Detection
Pathogen:
Measles virus
Illnesses and Diseases:
  • Measles
  • Subacute sclerosing panencephalitis (SSPE)
Specimen:

Urine, nasopharyngeal (NP) swab, throat swab. All specimens should be collected as soon as possible after rash onset (within 7 days for urine and 4 days for NP/throat swabs). Note: specimens collected later will still be accepted however the assay sensitivity will not be optimal. Viral isolates may also be sent.

 

Collection Method:

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.

 

Specimen Processing, Storage and Shipping:

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.

 

Transportation of Dangerous Goods:

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.

For additional guidance on the transport of infectious substances in other languages, please click on the link below.

http://www.who.int/ihr/capacity-strengthening/infectious-substances/en/

Patient Criteria:

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.

 

Accompanying Documentation:

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.

 

Comments:

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.

 

Methods and Interpretation of Results:

Extracted RNA from samples is tested by real-time RT-PCR for the measles nucleoprotein gene and measles hemagglutinin gene (2,3). Positive RT-PCR result is laboratory confirmation of measles infection, of any genotype. For suspected post-vaccine reactions, an additional RT-qPCR specifically targeting the vaccine virus (genotype A) is used for rapid typing (MeVA) (4). Positive MeVA result confirms presence of vaccine virus. Negative MeVA result, with a positive general RT-qPCR, is consistent with non-vaccine and genotyping is performed.

Turnaround Time:

7 calendar days. Stat testing available upon request.

 

Contact:
Phone: (204) 789-6024 or (204) 789-7055
Fax: (204) 318-2222
References:
  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. Tipples G, J Hiebert. Detection of measles, mumps and rubella viruses. Methods Mol Biol. 2011; 665: 183-193.
  3. Hummel KB, Lowe L, Bellini WJ, Rota PA. Development of quantitative gene-specific real-time RT-PCR assays for the detection of measles virus in clinical specimens. J Virol Methods. 2006; 132:166-73.
  4. 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.