Lab Testing for Rubella at the MDH Public Health Laboratory
Though rubella is no longer endemic in the United States, cases are likely 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.
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Lab Testing for Rubella at the MDH Public Health Laboratory (PDF: 65KB/2 pages)
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Report suspect rubella 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
If you suspect rubella 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 rubella immediately to MDH. Call while the patient is still in the office to ensure timely reporting and correct specimen collection.
To minimize transmission of rubella in health care settings, follow the same infection prevention guidelines as measles because the two diseases are hard to differentiate in the early stages of illness.
Rubella and measles should both be included in the differential diagnosis of patients presenting with an acute generalized rash and fever.
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
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
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)
- Cutaneous manifestations of syphillis
- Toxic Shock Syndrome
- Drug reactions (e.g. antibiotics)
- Contact dermatitis
Rubella Real-Time Polymerase Chain Reaction (RT-PCR, or PCR) is available for rubella case confirmation at the MDH Public Health Laboratory (MDH-PHL). Providers are asked to collect and send PCR specimens to MDH-PHL when rubella is suspected. Serologic testing for rubella is available at MDH-PHL and should only be considered if PCR specimens cannot be obtained. Please contact MDH directly at 651-201-5414 or 877-676-5414 to discuss requirements for serologic testing.
Clinical specimens for PCR should be taken as soon as rubella is suspected. Viral RNA is more likely to be detected when the specimen is collected as soon as possible after rash onset. Ideally, specimens for rubella PCR should be obtained within 0-3 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 the following specimens to the MDH-PHL, in order of preference:
- Throat swab
- Nasal, nasopharyngeal swab, or nasal wash
- Urine specimenǂ
ǂIf date of specimen collection is on day 5-9 after rash onset (day 0), urine is preferred over other specimens. If date of specimen collection is already more than 9 days past rash onset, PCR is less likely to detect viral presence and may give false negative results.
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 (two techniques):
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.
- Or -
Use sterile swabs to swab the nasopharynx and throat with either a viral culture swab or culturette. Place both swabs in a tube containing 2-3 ml of transport medium. The virus is extremely cell-associated, so attempt to swab the throat and nasal passages to collect epithelial cells. After swabbing, place the swab back in the transport sheath.
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.
- Balanced salt solutions (BSS)
- Sterile isotonic solutions
- Phosphate buffered salines (PBS)
- Stuart’s Liquid Media
- BBL Culture Swab
- 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.
- 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.
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