Measles (Rubeola) Virus, Qualitative Real-time PCR, Nasopharyngeal/Throat
Measles (Rubeola) Virus, Qualitative Real-time PCR, Nasopharyngeal/Throat
This test is used to diagnose measles (rubeola) infection.
Test Summary
Measles (Rubeola) Virus, Qualitative Real-time PCR, Nasopharyngeal/Throat
Test code: 39306
Clinical use
- Diagnose measles (rubeola) infection
Clinical background
Measles (rubeola) is a highly contagious, acute viral illness which can have serious complications. A characteristic maculopapular rash appears about 3 to 5 days after the first symptoms. Symptoms begin 7 to 14 days after contact and consist of high fever, cough, runny nose (coryza) and conjunctivitis - the 3 Cs. In 2025 over 1,000 confirmed cases of measles across 33 states were reported to the Centers for Disease Control and Prevention (CDC), with roughly 88% of these cases being outbreak-related. At least 27 outbreaks occurred in 2025 as of June compared to 16 in 2024.1
Antiviral therapy is not available for measles, but timely diagnosis of a measles infection may allow clinicians to initiate early supportive care and limit transmission.2 For diagnosis, the CDC recommends both serology (IgM antibody testing) and real-time polymerase chain reaction (PCR), preferably of nasopharyngeal (NP) or throat swabs; however, urine specimens may also be used.2 IgM antibodies may be detected 3 days after rash onset when testing is done too early, IgM levels can be low and cause false-negative results.3 False-positive IgM results can also occur due to the presence of rheumatoid factor (RF) or due to to cross-reactivity with other viruses, including parvovirus B19 and Epstein-Barr virus.4
Real-time PCR detects viral RNA before IgM becomes detectable and can thus support a measles diagnosis earlier in disease progression.5–7 By detecting nucleotide sequences specific to measles, real-time PCR also overcomes the cross-reactivity and lack of specificity seen with IgM testing.4 In addition, the sensitivity of real-time PCR for measles is 80% within 3 days of rash onset and remains above 50% as late as 10 to 14 days after onset.7,8 In comparison, the sensitivity of viral culture for measles is only 65% within 3 days of rash onset and declines to 10% after 10 to 14 days.7,8
Quest Diagnostics offers the Measles (Rubeola) Virus, Qualitative Real-time PCR, Nasopharyngeal/Throat test (test code 39306) as a sensitive diagnostic test for measles RNA in clinical specimens.
Note: Quest also offers serologic tests for both diagnosis and immunity testing for measles including Measles Antibodies (IgG, IgM) (test code 34166). Measles Antibody (IgM) (test code 34256) and Measles Antibody (IgG) (test code 964) are separately available. Laboratory testing for immunity is based on the detection of measles IgG. Patients without a documented immunization with the MMR vaccine who have measles IgG results that are negative or equivocal should be vaccinated or revaccinated.5
Individuals suitable for testing
- Individuals who present with symptoms of measles infection (ie, maculopapular rash, cough, coryza, conjunctivitis), especially those who are unvaccinated or have other risk factors, such as recent international travel
Method
- Real-time PCR-based amplification of extracted nucleic acids
Interpretive information
A "detected" result confirms a measles diagnosis.5
A "not detected" result is consistent with the absence of measles from the patient specimen but does not exclude the diagnosis, because real-time PCR is affected by the timing of specimen collection and other factors. If measles is suspected and rubeola virus RNA is not detected, consider measles IgM/IgG testing.
Diagnosis of measles infection should not rely solely on the result of this test. Test selection and interpretation, diagnosis, and patient management decisions should be based on the physician’s education, clinical expertise, and assessment of the patient.
References
- Measles cases and outbreaks. Centers for Disease Control and Prevention. Updated June 25, 2025. Accessed June 25, 2025. https://www.cdc.gov/measles/data-research/index.html#cdc_data_surveillance_section_4-map-of-measles-cases-in-2024-2025
- Gastanaduy PA, Redd SB, Clemmons NS, et al. Measles. In: Roush SW, Baldy LM, Kirkconnell MA, eds. Manual for the Surveillance of Vaccine-Preventable Diseases. Centers for Disease Control and Prevention; 2025. Accessed June 11, 2025. https://www.cdc.gov/surv-manual/php/table-of-contents/chapter-7-measles.html?CDC_AAref_Val=https://www.cdc.gov/vaccines/pubs/surv-manual/chpt07-measles.html
- Kondamudi NP, Tobin EH, Waymack JR. Measles. In: StatPearls [Internet]. Updated May 5, 2025. Accessed June 11, 2025. https://www.ncbi.nlm.nih.gov/books/NBK448068/
- Woods CR. False-positive results for immunoglobulin M serologic results: explanations and examples. J Pediatric Infect Dis Soc. 2013;2:87-90. doi:10.1093/jpids/pis133
- Measles serology testing. Centers for Disease Control and Prevention. Updated May 9, 2024. Accessed June 12, 2025. https://www.cdc.gov/measles/php/laboratories/serology.html?CDC_AAref_Val=https://www.cdc.gov/measles/lab-tools/serology.html
- Genetic analysis of measles viruses. Centers for Disease Control and Prevention. Updated June 7, 2024. Accessed June 12, 2025. https://www.cdc.gov/measles/php/laboratories/genetic-analysis.html?CDC_AAref_Val=https://www.cdc.gov/measles/lab-tools/genetic-analysis.html
- Detection of viral RNA by RT-PCR for the confirmation of measles and rubella infection. In: Manual for the Laboratory-Based Surveillance of Measles, Rubella, and Congenital Rubella Syndrome. Third edition. World Health Organization; 2018. Accessed March 24, 2023. https://www.technet-21.org/en/manual-introduction/chapter-6-detection-of-viral-rna-by-rt-pcr-for-the-confirmation-of-measles-and-rubella-infection
- Recommendations from an ad hoc Meeting of the WHO Measles and Rubella Laboratory Network (LabNet) on use of alternative diagnostic samples for measles and rubella surveillance. Centers for Disease Control and Prevention. MMWR Morb Mortal Wkly Rep. 2008;57(24):657-660.
Content reviewed 6/2025
This test is used to diagnose measles (rubeola) infection.
Test Summary
Measles (Rubeola) Virus, Qualitative Real-time PCR, Nasopharyngeal/Throat
Test code: 39306
Clinical use
- Diagnose measles (rubeola) infection
Clinical background
Measles (rubeola) is a highly contagious, acute viral illness which can have serious complications. A characteristic maculopapular rash appears about 3 to 5 days after the first symptoms. Symptoms begin 7 to 14 days after contact and consist of high fever, cough, runny nose (coryza) and conjunctivitis - the 3 Cs. In 2025 over 1,000 confirmed cases of measles across 33 states were reported to the Centers for Disease Control and Prevention (CDC), with roughly 88% of these cases being outbreak-related. At least 27 outbreaks occurred in 2025 as of June compared to 16 in 2024.1
Antiviral therapy is not available for measles, but timely diagnosis of a measles infection may allow clinicians to initiate early supportive care and limit transmission.2 For diagnosis, the CDC recommends both serology (IgM antibody testing) and real-time polymerase chain reaction (PCR), preferably of nasopharyngeal (NP) or throat swabs; however, urine specimens may also be used.2 IgM antibodies may be detected 3 days after rash onset when testing is done too early, IgM levels can be low and cause false-negative results.3 False-positive IgM results can also occur due to the presence of rheumatoid factor (RF) or due to to cross-reactivity with other viruses, including parvovirus B19 and Epstein-Barr virus.4
Real-time PCR detects viral RNA before IgM becomes detectable and can thus support a measles diagnosis earlier in disease progression.5–7 By detecting nucleotide sequences specific to measles, real-time PCR also overcomes the cross-reactivity and lack of specificity seen with IgM testing.4 In addition, the sensitivity of real-time PCR for measles is 80% within 3 days of rash onset and remains above 50% as late as 10 to 14 days after onset.7,8 In comparison, the sensitivity of viral culture for measles is only 65% within 3 days of rash onset and declines to 10% after 10 to 14 days.7,8
Quest Diagnostics offers the Measles (Rubeola) Virus, Qualitative Real-time PCR, Nasopharyngeal/Throat test (test code 39306) as a sensitive diagnostic test for measles RNA in clinical specimens.
Note: Quest also offers serologic tests for both diagnosis and immunity testing for measles including Measles Antibodies (IgG, IgM) (test code 34166). Measles Antibody (IgM) (test code 34256) and Measles Antibody (IgG) (test code 964) are separately available. Laboratory testing for immunity is based on the detection of measles IgG. Patients without a documented immunization with the MMR vaccine who have measles IgG results that are negative or equivocal should be vaccinated or revaccinated.5
Individuals suitable for testing
- Individuals who present with symptoms of measles infection (ie, maculopapular rash, cough, coryza, conjunctivitis), especially those who are unvaccinated or have other risk factors, such as recent international travel
Method
- Real-time PCR-based amplification of extracted nucleic acids
Interpretive information
A "detected" result confirms a measles diagnosis.5
A "not detected" result is consistent with the absence of measles from the patient specimen but does not exclude the diagnosis, because real-time PCR is affected by the timing of specimen collection and other factors. If measles is suspected and rubeola virus RNA is not detected, consider measles IgM/IgG testing.
Diagnosis of measles infection should not rely solely on the result of this test. Test selection and interpretation, diagnosis, and patient management decisions should be based on the physician’s education, clinical expertise, and assessment of the patient.
References
- Measles cases and outbreaks. Centers for Disease Control and Prevention. Updated June 25, 2025. Accessed June 25, 2025. https://www.cdc.gov/measles/data-research/index.html#cdc_data_surveillance_section_4-map-of-measles-cases-in-2024-2025
- Gastanaduy PA, Redd SB, Clemmons NS, et al. Measles. In: Roush SW, Baldy LM, Kirkconnell MA, eds. Manual for the Surveillance of Vaccine-Preventable Diseases. Centers for Disease Control and Prevention; 2025. Accessed June 11, 2025. https://www.cdc.gov/surv-manual/php/table-of-contents/chapter-7-measles.html?CDC_AAref_Val=https://www.cdc.gov/vaccines/pubs/surv-manual/chpt07-measles.html
- Kondamudi NP, Tobin EH, Waymack JR. Measles. In: StatPearls [Internet]. Updated May 5, 2025. Accessed June 11, 2025. https://www.ncbi.nlm.nih.gov/books/NBK448068/
- Woods CR. False-positive results for immunoglobulin M serologic results: explanations and examples. J Pediatric Infect Dis Soc. 2013;2:87-90. doi:10.1093/jpids/pis133
- Measles serology testing. Centers for Disease Control and Prevention. Updated May 9, 2024. Accessed June 12, 2025. https://www.cdc.gov/measles/php/laboratories/serology.html?CDC_AAref_Val=https://www.cdc.gov/measles/lab-tools/serology.html
- Genetic analysis of measles viruses. Centers for Disease Control and Prevention. Updated June 7, 2024. Accessed June 12, 2025. https://www.cdc.gov/measles/php/laboratories/genetic-analysis.html?CDC_AAref_Val=https://www.cdc.gov/measles/lab-tools/genetic-analysis.html
- Detection of viral RNA by RT-PCR for the confirmation of measles and rubella infection. In: Manual for the Laboratory-Based Surveillance of Measles, Rubella, and Congenital Rubella Syndrome. Third edition. World Health Organization; 2018. Accessed March 24, 2023. https://www.technet-21.org/en/manual-introduction/chapter-6-detection-of-viral-rna-by-rt-pcr-for-the-confirmation-of-measles-and-rubella-infection
- Recommendations from an ad hoc Meeting of the WHO Measles and Rubella Laboratory Network (LabNet) on use of alternative diagnostic samples for measles and rubella surveillance. Centers for Disease Control and Prevention. MMWR Morb Mortal Wkly Rep. 2008;57(24):657-660.
Content reviewed 6/2025