Lab Testing for Measles at the MDH Public Health Laboratory

Though measles is no longer endemic in the United States, outbreaks continue to occur as a result of internationally imported or import-linked cases. Continued success in disease reduction is dependent on maintaining awareness of the disease along with improving vaccination rates.

Download PDF version formatted for print:
Lab Testing for Measles at the MDH Public Health Laboratory (PDF)

On this page:
Report suspect measles cases immediately
Clinical features and differential diagnoses
Lab tests offered at MDH-PHL
Preferred specimens: PCR
Specimen collection: PCR
Approved swabs and media
Transporting specimens to MDH

Report suspect measles cases immediately

If you suspect measles in a patient:

  • Call MDH at 651-201-5414 or toll-free at 1-877-676-5414
  • Provide clinical details
  • Collect specimens for PCR testing

Health care facilities are required by law to report suspect cases of measles immediately to MDH. Call while the patient is still in the office to ensure timely reporting and correct specimen collection.

Follow infection prevention guidelines to minimize measles transmission in health care settings.

Clinical features and differential diagnoses

Measles and rubella should both be included in the differential diagnosis of patients presenting with an acute generalized rash and fever.

Measles is characterized by:

  • A generalized maculopapular rash lasting
    3 days or more
  • Fever of 101°F (38.3°C) or higher
  • Cough, coryza, or conjunctivitis

Rubella is characterized by:

  • Acute onset of a maculopapular rash lasting
    less than 3 days
  • Fever higher than 99°F (37.2°C)
  • Arthralgia, arthritis, lymphadenopathy, or conjunctivitis

MDH also encourages health care providers to consider other infectious and non-infectious etiologies that may cause generalized rash, including: 

  • Coxsackievirus, Echovirus, Epstein-Barr virus, Erythema infectiosum (Fifth Disease), HIV, Kawasaki disease, Roseola infantum, Scarlet fever, Pharyngoconjunctival fever
  • Dengue fever, Rocky Mountain spotted fever
  • Dermatologic manifestations of Viral hemorrhagic fevers (VHFs)
  • Toxic Shock Syndrome, cutaneous manifestations of syphilis
  • Drug reactions (e.g. antibiotics, contact dermatitis)

Lab tests offered at MDH Public Health Laboratory

Measles Real-Time Polymerase Chain Reaction (RT-PCR, or PCR) is available for measles case confirmation at the MDH Public Health Laboratory (MDH-PHL). Providers are asked to collect and send PCR specimens to MDH-PHL when measles is suspected.

Serologic testing for diagnostic purposes is no longer available at MDH-PHL. If serum is collected, it should be drawn at least 72 hours past rash onset and submitted to the facility’s normal reference laboratory. Serologic testing can create false positive measles IgM results from cross reacting to other viruses, including erythrovirus (parvovirus), rubella, human herpes virus 6 (including roseola), and rheumatoid factor antibodies (may be generated with tuberculosis, trypanosomiasis, EBV (mono), CMV, influenza A and hepatitis A).

Preferred specimens: PCR

Clinical specimens for PCR should be taken as soon as measles is suspected. Viral RNA is more likely to be detected when the specimen is collected as soon as possible after rash onset. Specimens for measles PCR should be obtained within five days of rash onset (0-9 days at most). Consider the rash onset date as day ‘0.’ Viral isolation requires the same specimens and may be done if PCR is negative.

Please send specimens to the MDH-PHL. The type and number of specimens sent varies for each case based on rash onset and suspicion level.

  • On day 0-5 of rash, collect a throat swab*
  • On day 6-9 of rash, collect a throat swab and a urine specimen**

*If a throat swab cannot be collected, a nasal specimen can be sent instead; however, a throat swab is the preferred specimen for measles PCR testing. If case is clinically compatible and reports an exposure to measles or has had recent travel, attempt collection of all three specimens (throat, nasal and urine).
**If date of specimen collection is already more than nine days past rash onset, PCR is not valid.

Specimen collection: PCR

Throat swab: Vigorously swab tonsillar areas and posterior nasopharynx with a viral culturette. Use tongue blade to depress tongue to prevent contamination of swab with saliva. Place swab into 2-3 ml of viral transport medium (VTM).

Nasal or nasopharyngeal swab: Use sterile swabs to swab the nasal passage or the nasopharynx with either a viral culture swab or culturette. Place swab into VTM.

Nasal wash: Use a syringe attached to a small plastic tube and 500 µl of VTM. After placing VTM in the nostril, aspirate as much of the material as possible and rinse the tube with the original (500 µl) of VTM.

Urine specimen: Collect 10-40 ml of urine in a STERILE 50 ml centrifuge tube or a urine specimen container. First-morning voided specimens are ideal, but any urine collection is adequate. Have patient void directly into container, collecting from the first part of the urine stream if possible.

Approved swabs and media

Appropriate

  • VTM
  • M5
  • M4
  • MEM
  • Saline
  • Balanced salt solutions (BSS)
  • Sterile isotonic solutions
  • Phosphate buffered salines (PBS)
  • Stuart’s Liquid Media
  • BBL Culture Swab
  • Culturettes

Not Appropriate

  • Wood-tipped applicators
  • Calcium-alginate tipped swabs
  • Charcoal swabs
  • Gel swabs
  • Anaerobic media

NOTE: Flocked swabs are preferred for specimen collection. VTM containing ~1% protein (e.g., bovine serum albumin or gelatin) best supports measles virus; however, sterile saline is acceptable.

Transporting specimens to MDH

  • Label all tubes/containers with the following information:
    • Patient name
    • Patient date of birth
    • Date specimen collected
    • Specimen type
  • Include an Infectious Disease Testing and Submission Form for each specimen. Fill out the form as completely as possible and be sure to indicate which test is requested.
  • Specimens should be kept and transported at refrigeration temperature (2-8° C).
  • Before shipping, always consult with an MDH epidemiologist at 651-201-5414 or 877-676-5414.
  • Send to MDH Public Health Laboratory via overnight shipping.
  • For help with packaging and shipping, call MDH-PHL Biological Accessioning at 651-201-4953.
  • Results will be sent via fax to the submitting laboratory.

Send specimens to arrive Monday-Friday before 4:30 p.m. to:
MDH Public Health Laboratory
Attn: Biological Accessioning
601 Robert St. N.
St. Paul, MN 55155-2531

Updated Friday, June 19, 2015 at 11:31AM