Rubella Virus

Rubella is a contagious viral illness, which, prior to vaccination, was responsible for a significant number of fetal losses and congenital abnormalities. The reported number of rubella cases in the U.S. is low enough that the CDC considers it eliminated in 2004.

Diagnosis

Indications for Testing

  • Prenatal screening for evidence of immunity (presence of maternal antibodies)
  • Typical symptoms  in unvaccinated patient – rash, fever, headache, pink eye, malaise, lymphadenopathy, cough, rhinitis

Criteria for Diagnosis

  • World Health Organization (WHO) case definition for congenital rubella syndrome (CRS)
    • Suspected case – any infant <1 year in whom a health worker suspects CRS
      • Infant presents with heart disease and/or suspicion of deafness and/or ≥1 of the following eye signs – white pupil (cataract), diminished vision, pendular movement of the eyes (nystagmus), squint, smaller eye ball (microphthalmos), or larger eye ball (congenital glaucoma)
      • Infant’s mother has a history of suspected or confirmed rubella during pregnancy, even when the infant shows no signs of CRS
    • Clinically confirmed case – an infant in whom a qualified physician detects 2 of the complications in section A or 1 from section A and 1 from section B
      • Section A – cataracts, congenital glaucoma, congenital heart disease, hearing impairment, pigmentary retinopathy
      • Section B – purpura, splenomegaly, microcephaly, developmental delay, meningoencephalitis, radiolucent bone disease, jaundice with onset within 24 hours of birth
    • Laboratory-confirmed case – infant with rubella IgM antibody who has clinically confirmed CRS
    • Congenital rubella infection – infant with rubella IgM antibody who does not have clinically confirmed CRS
  • Rubella/German measles case definition (CDC, 2013)

Laboratory Testing

Differential Diagnosis

Background

Epidemiology

  • Incidence – <10 cases per year in the U.S. (all contracted outside the country since 2012)
    • CRS – <2/100,000 births
  • Age – usually children who are unvaccinated
  • Transmission
    • Via droplets, aerosol particles – close contact required

Organism

  • Rubella, an RNA virus, is a member of the Togaviridae family
  • Virus infects cells in the upper respiratory tract and replicates in the lymphoid system; virus then spreads to other organs

Clinical Presentation

  • Transmission can occur up to 7 days before and 7 days after onset of rash
  • In children and adults, infection usually results in mild, exanthematous disease
    • Adults are more likely to experience prodromal phase – fever, headache, sore throat, cough, conjunctivitis
    • Rare complications – arthralgias and arthritis, thrombocytopenia, hemorrhage, and encephalitis
  • In pregnant women, particularly during first trimester, infection can result in fetal death or congenital abnormalities
    • Disease can be asymptomatic
    • Congenital abnormalities include
      • Ophthalmologic – cataracts, glaucoma, iris hypoplasia, retinopathy
      • Otorhinolaryngologic – sensorineural or central deafness
      • Cardiac – patent ductus arteriosus, pulmonary stenosis, pulmonary arterial hypoplasias, myocarditis
      • Central nervous system – developmental delay with central nervous system calcifications, microcephaly
      • Dermatologic – petechia, purpura
    • 10-20% of newborns infected in utero will die during the first year of life
    • Because complications in utero are so severe, diagnosis during first trimester may result in decision to terminate pregnancy
    • Delayed manifestations

Prevention

  • Vaccination programs have resulted in marked decrease in infections
    • Estimated >95% of children in U.S. are vaccinated (recommended between ages 12-15 months)
    • Vaccine is live, attenuated virus and contraindicated in pregnant women

ARUP Lab Tests

Aid in diagnosis of suspected rubella infection

If test results are equivocal, repeat testing in 10-14 days 

Determine seroreactivity of women of childbearing age or provide evidence of vaccination/past infection

Related Tests

Not recommended as a stand-alone test

Panel that combines rubella IgG and IgM antibodies is preferred

Not recommended for diagnosing congenital infections in newborns; tests should be selected individually to target the most likely infectious agents

May be used in pregnant women to assess past exposure or immunization to Toxoplasma, rubella, cytomegalovirus (CMV), and herpes simplex virus (HSV)

Not recommended for diagnosing congenital infections in newborns; tests should be selected individually to target the most likely infectious agents

Medical Experts

Contributor

Couturier

Marc Roger Couturier, PhD, D(ABMM)

Associate Professor of Clinical Pathology, University of Utah

Medical Director, Microbial Immunology, Parasitology and Fecal Testing, and Infectious Disease Antigen Testing at ARUP Laboratories

References

Additional Resources
Resources from the ARUP Institute for Clinical and Experimental Pathology®