rubella (German measles, 3rd disease)

Etiology

• rubella virus
• transmission
  • probably via respiratory droplets
  • patients are most contagious when rash is erupting
  • viral shedding occurs from 10 days prior to & 15 days after eruption of rash

Epidemiology

• progress on elimination of measles & rubella 2000-2011

Clinical manifestations

• postnatal infection
  • incubation period is 15-21 days
  • prodromal symptoms may precede rash by 1-5 days
  • lymphadenopathy
    • begins 1-5 days prior to the rash
    • suboccipital, postauricular & general
    • may be the only sign of infection
  • rash appears at the same time as the low-grade fever
    • appears 1st on the face, then progresses down the body
    • maculopapular rash, discrete often pinpoint lesions occasionally coalescing on the trunk
    • duration of rash 3-5 days
    • occasional desquamation during convalescence
  • petechial lesions on soft palate
  • mild conjunctivitis
  • fever
    • low-grade or absent
    • resolves by 1st day of rash
• congenital infection
  • manifestations are most severe the earlier in pregnancy the illness occurs
  • fetal demise
  • premature delivery
  • congenital anomalies
    • nerve deafness (80-90%)
    • growth retardation (50-85%)
    • congenital cataracts (35%) (image)
    • retinopathy (35%) (image)
    • patent ductus arteriosus (30%)
    • pulmonary artery &/or valvular stenosis (30%)
    • atrial septal defect
    • mental retardation (10-20%)
    • meningoencephalitis (10-20%)
    • behavioral disorders (10-20%)
    • hepatosplenomegaly (10-20%)
    • bone lesions (10-20%)
    • thrombocytopenic purpura (5-10%)

Laboratory

• generally not useful in diagnosing acute disease
• rubella virus antigen in tissue/body fluid
  • specimen from nose, throat, urine or other body fluid for diagnosis of congenital infection
• rubella virus serology:
  • confounded by false positives
  • presence in infant suggests congenital infection
• rubella virus RNA
  • rubella virus E1 gene
• see ARUP consult

Complications

(rare)

• arthritis & arthralgia more common in adult women
• thrombocytopenia
• leukopenia
• encephalitis (very rare)

Differential diagnosis

• enteroviral infection
  • shorter incubation period (3-7 days)
  • more common in younger children
  • frequently with higher fever
  • seasonal, more common in summer & fall
• measles
• scarlet fever
• infectious mononucleosis
• toxoplasmosis
• roseola
• erythema infectiosum
• drug reactions

Management

• symptomatic treatment for postnatal infection
• pharmacologic agents
  • acetaminophen for fever
  • aspirin for arthralgia
• prophylaxis:
  • MMR vaccine
  • immune globulin for susceptible pregnant women with < 20 gestation within 72 hours of exposure (controversial)
• isolation from susceptible individuals until 7 days after the rash
• complete Confidential Morbidity Report; rubella is a reportable disease

More general terms

• viral infection
• childhood exanthem (numbered diseases)

Additional terms

• measles, mumps & rubella combined vaccine (MMR)
• rubella virus