Rubella Virus

 

Clinical Background

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 in the U.S.
  • Age – usually young children who are unvaccinated
  • Transmission
    • Via droplets, aerosol particles – close contact required

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
  • The virus then 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
    • Adults are more likely to experience prodromal phase – fever, headache, sore throat, cough, conjunctivitis
    • Rare complications include arthralgias and arthritis, thrombocytopenia, hemorrhage and encephalitis
  • In pregnant women, particularly during 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)
    • Click here for WHO case definition for congenital rubella syndrome
      WHO Case Definition for Congenital Rubella Syndrome (CRS)
      • Suspected case
        • Any infant less than 1 year of age in whom a health worker suspects CRS
          • A health worker should suspect CRS when an infant presents with heart disease and/or suspicion of deafness and/or one or more 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)
          • When an infant’s mother has a history of suspected or confirmed rubella during pregnancy, even when the infant shows no signs of CRS
      • Clinically confirmed CRS case
        • An infant in whom a qualified physician detects two of the complications in section A or one from section A and one from section B:
          • Section A: cataracts, congenital glaucoma, congenital heart disease, hearing impairment, pigmentary retinopathy
          • Section B: purpura, splenomegaly, microcephaly, mental retardation, meningoencephalitis, radiolucent bone disease, jaundice with onset within 24 h after birth
      • Laboratory-confirmed CRS case – an infant with rubella IgM antibody who has clinically confirmed CRS
      • Congenital rubella infection – an infant with rubella IgM antibody who does not have clinically confirmed CRS
      • Disease can be asymptomatic
      • Congenital abnormalities include:
        • Eye defects – cataracts, glaucoma, iris hypoplasia, retinopathy
        • Sensorineural or central deafness
        • Congenital heart disease (patent ductus arteriosus, pulmonary stenosis, pulmonary arterial hypoplasias)
        • Central nervous system – mental retardation with central nervous system calcifications, microcephaly
    • 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

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