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Disease/health condition - Measles, Vaccine-preventable diseases
Measles nucleic acid amplification test
Setting:
2. Laboratory
Tiered Testing Service:
Regional or provincial hospital with laboratory
Assay format
NAAT
Information History
First added in 2020
Purpose type
Diagnosis
Purpose
To diagnose clinically suspected measles infection.
Specimen types
Oral fluid, Throat swab, Nasopharyngeal swab, Nasopharyngeal aspirate, Urine
WHO prequalified or recommended products
N/A
GMDN

49276

Measles virus nucleic acid IVD, kit, nucleic acid technique (NAT)

A collection of reagents and other associated materials intended to be used for the qualitative and/or quantitative detection of nucleic acid from Measles virus in a clinical specimen, using a nucleic acid technique (NAT).

The medical device term(s), code(s) and definition(s) in this section were retrieved from databases external to WHO. As there might be more than one name, definition and “Nomenclature Code” related to the specific medical device, please consult https://gmdnagency.org GMDN ®. © GMDN Agency 2005-2024
EMDN

W0105040704

MEASLES - NA REAGENTS

The code(s) and term(s) in this section were observed and retrieved from public databases and have not been validated by health regulatory authorities. Please consult your regulatory agency and EMDN site: https://webgate.ec.europa.eu/dyna2/emdn
WHO supporting publications
World Health Organization. (‎2007)‎. Manual for the laboratory diagnosis of measles and rubella virus infection, 2nd ed. World Health Organization. https://iris.who.int/handle/10665/70211 ; World Health Organization. (‎2008)‎. Immunological basis for immunization : rubella. World Health Organization. https://iris.who.int/handle/10665/43922
Technical specifications
N/A
Related Medical Devices in MeDevIS
SAGE IVD recommended including the measles nucleic acid test category in the third EDL:
• as a disease-specific IVD for use in clinical laboratories (EDL 3, Section II.b, Vaccine-preventable diseases);
• using a nucleic acid test format;
• to diagnose clinically suspected measles infection.
Measles is a disease of public health concern, and it is important to detect outbreaks early. Measles IgM testing may be the gold standard for identifying cases, but it has limitations. In particular, detection of measles IgM depends on timing of specimen collection and may need to be complemented with a PCR test. Supplementary testing may also be needed to confirm measles IgM-positive tests in a low measles incidence context (to rule out false positives). Measles PCR is recommended in WHO guidelines, both for acute diagnosis in the early stages of disease and symptom onset, when IgM can still be negative, and to confirm IgM-positive cases in low-prevalence settings. Because the test has become part of the case definition, it is difficult to gather data on its accuracy. In this case, SAGE IVD looked for evidence that the PCR test makes a valuable contribution in terms of the number of cases detected by PCR, particularly where IgM is negative. And the studies submitted do provide sufficient evidence of this. SAGE IVD noted that specialized equipment and highly skilled personnel are required to perform the PCR test and that it is more costly than either the measles IgM or IgG tests. As such, it may only be applicable where high-level PCR testing is available. In LMICs and resource-constrained settings, it may only be made available at a regional or central level. SAGE IVD noted that if more robust assays become available that can be performed close to POC, they could reduce the turnaround time for case confirmation and help to rapidly identify cases in an outbreak situation.
A positive RT-PCR result for measles is considered to confirm infection, and there are no studies comparing the results of this test against an independent reference standard (given that it is effectively part of the case definition). The test is embedded in WHO protocols for testing for measles. Substantial evidence exists showing that significant numbers of measles cases are detected only by using RT-PCR, particularly among the vaccinated population. There was also evidence that RT-PCR has a greater ability to detect measles in samples taken in the first few days after the rash appears. Figures from the studies suggest that 4–16% of samples were IgM negative and PCR positive.
World Health Organization. (‎2021)‎. The selection and use of essential in vitro diagnostics: report of the third meeting of the WHO Strategic Advisory Group of Experts on In Vitro Diagnostics, 2020 (‎including the third WHO model list of essential in vitro diagnostics)‎. World Health Organization. https://iris.who.int/handle/10665/339064