Rubella

Aka: Rubella, Third Viral Exanthem of Childhood, German Measles, Three Day Measles, Congenital Rubella Syndrome

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II. Epidemiology

  1. Incidence of Rubella cases
    1. U.S. Cases in 1964-5: 12 million cases
    2. U.S. Cases in 2000: 176 cases
  2. Incidence of congenital Rubella cases
    1. U.S. Cases in 1964-5: 20,000 cases
    2. U.S. Cases in 2000: 9 cases
    3. U.S. Cases in 2015: 6 cases

III. Pathophysiology

  1. Rubella is the only member of the Genus rubivirus in the Togaviridae family
    1. Rubella is a pleomorphic RNA Virus that is among the TORCH Viruses (causing serious congenital disease)
  2. Togaviridae are otherwise primarily composed of Arboviruses (arthropod-borne), Alphaviruses that cause Encephalitis
    1. Togaviridae are enveloped, Icosahedral, single stranded RNA Viruses
    2. Togaviridae are Message Sense RNA Viruses (Positive Stranded, +ssRNA)
      1. Message sense RNA (+ssRNA) are identical to Messenger RNA (mRNA)
      2. Like mRNA, +ssRNA may be immediately translated by host ribosomes into Protein
  3. Rubella Transmission
    1. Person to person via oral droplets
    2. Vertical transmission (transplacental) results in congenital Rubella (90% risk in first trimester)
    3. Up to 60% transmission in susceptible family

IV. Symptoms

  1. Subclinical in 50% of cases
  2. Known also as "Three Day Measles" (shorter, more mild course than Measles)
  3. Viral prodrome precedes the rash (described below)
    1. Fever
    2. Pharyngitis
    3. Mild Upper Respiratory Infection symptoms
    4. Lymphadenopathy
    5. Headache

V. Signs

  1. Mild Fever
  2. Significantly tender Lymphadenopathy
    1. Retroauricular, posterior auricular, Occipital Lymphadenopathy
  3. Rash
    1. Red Maculopapular rash with areas of confluence, Flushing
    2. Distribution and Evolution
      1. Initially, exanthem may cover Soft Palate and face
      2. Later, rash begins on face and spreads to cover trunk
      3. Rash usually clears by Day 3 (hence the name: Three Day Measles)
    3. Associated findings
      1. Mild Pruritus

VI. Differential Diagnosis

  1. See Rash in the Febrile Patient
  2. Mononucleosis
    1. Also causes significant Lymphadenopathy
  3. Measles
    1. Conjunctivitis and Koplik Spots
    2. More severe course

VII. Complications: Congenital Rubella Syndrome

  1. Rubella is one of the TORCH Viruses
  2. Congenital Rubella primarily affects 3 systems
    1. Cardiovascular
      1. Patent Ductus Arteriosus
      2. Interventricular septal defect
      3. Pulmonary artery stenosis
    2. Eye
      1. Congenital Cataracts
      2. Chorioretinitis
    3. Neurologic
      1. Intellectual Disability
      2. Microcephaly
      3. Deafness
  3. Pregnant women should avoid Rubella exposure
    1. Avoid throughout pregnancy (especially early)
    2. Avoid exposure to infants with congenital Rubella
      1. Very high risk due to prolonged shedding

VIII. Complications: Miscellaneous

  1. Encephalitis (1 case per 6,000 Rubella infections)
    1. Mortality from Encephalitis approaches 20%
  2. Arthritis (immune complex)
  3. Thrombocytopenia (1 case per 3000 Rubella infections)
  4. Immune-complex mediated Arthritis
    1. Primarily seen in young women

IX. Management: High risk exposure occurs early in pregnancy

  1. Consider therapeutic abortion
  2. Give Rubella Immunoglobulin

X. Prevention

  1. Primary Series
    1. MMR Vaccine at Ages 12-15 months, and 4-6 years
  2. Preconception Counseling
    1. Test Rubella Immunity
    2. Vaccinate women not immune to Rubella

XI. References

  1. Spencer (2017) Am Fam Physician 95(12): 786-94 [PubMed]

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