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The Physician's Guide to Laboratory Test Selection and InterpretationRubella
The reported number of rubella cases in the U.S. over the last 5 years is low enough for the Centers for Disease Control (CDC) to state that the endemic disease has been eliminated.
Epidemiology
- Incidence – <25 cases a year
- Transmission
- Via droplets
Organism
- Rubella, an RNA virus, is the only member of the Togaviridae family
- Virus infects cells in the upper respiratory tract and replicates in the lymphoid system
- Thereafter the virus spreads to other organs
Clinical Presentation
- Transmission can occur up to 7 days before and 7 days after onset of the rash
- In children and adults, infection usually results in mild, exanthematous disease
- Rare complications include arthritis, thrombocytopenia, hemorrhage and encephalitis
- In pregnant women, particularly first trimester, infection can result in fetal death or congenital abnormalities
- The spectrum of congenital defects called TORCH syndrome occurs with maternal exposure to rubella (also to Toxoplasma gondii, cytomegalovirus and herpes simplex virus)
- Disease can be asymptomatic
- Defects include:
- Cataracts
- Deafness
- Glaucoma
- Congenital heart disease
- Mental retardation with central nervous system calcifications
- The spectrum of congenital defects called TORCH syndrome occurs with maternal exposure to rubella (also to Toxoplasma gondii, cytomegalovirus and herpes simplex virus)
- 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
Diagnosis
- Laboratory testing
- In primary rubella infection, the appearance of clinical symptoms is associated with the appearance of both IgG and IgM antibodies
- IgM antibodies – detectable a few days after onset of symptoms; peak 7-10 days later
- Test women prior to pregnancy to confirm presence of IgG antibodies
- In primary rubella infection, the appearance of clinical symptoms is associated with the appearance of both IgG and IgM antibodies
Differential diagnosis
- Parvovirus B19
- Human herpesvirus 6 (HHV6)
- Measles
- West Nile virus
- Enterovirus
Treatment
- Treatment is supportive and symptom-based
Prevention
- Vaccination programs have resulted in marked decrease in infections
- Estimated >95% of children in U.S. are vaccinated
- Vaccine is live, attenuated virus and contraindicated in pregnant women
