Rubella virus

Rubella virus (German measles)

• Fever, rash, ± arthritis
• Mnemonic: "German toga party", "Oct-toga-fest"
• Congenital syndrome: deafness, cataracts, and CHD

Microbiology

• RNA virus in the Togaviridae family, genus Rubivirus

Epidemiology

• Seasonal, in spring, if no vaccine
• Less contaggious than measles, spread by respiratory droplets
  • Most contagious while the rash is erupting, but ranges from 10 days prior to 15 days after
  • Infants with congenital rubella can shed it in body fluids for months
• Epidemics happened every 6 to 9 years, with larger epidemics every 30 years
• Worldwide, until it was eliminated in the Americas in 2009
  • All cases are imported

Clinical Presentation

• Incubation period 18 days (range 12 to 23 days)
• Benign after birth (postnatal rubella)
• In adults, prodrome of fever, malaise, and anorexia, followed by the rash
• Rash appears along with development of immunity
  • Rash starts at the head and moves down
  • Maculopapular
  • May desquamate during healing
  • May be absent
  • Can have Forschheimer's spots (petechial lesions on the soft palate), but not pathognomonic
• Adenopathy can last weeks, primarily posterior auricular, posterior cervical, and suboccipital
• Can develop arthritis in a third, usually fingers, wrists, and knees
  • Onset soon after the rash, can take up to a month to resolve
• Hemorrhage from thrombocytopenia and vascular damage, more commonly in children
• Encephalitis is rare

Congenital rubella syndrome

• Deafness, cataracts, glaucoma, congenital heart disease, and mental retardation
• Low birth weight, thrombocytopenic purpura, organomegaly, meningoencephalitis, retinopathy, PDA, PS, developmental disorders, cryptorchidism, inguinal hernia

Diagnosis

• Acute and convalescent ELISA serology, or single IgM titre
• Can do PCR for viral RNA on throat swabs, CSF, or amniotic fluid

Management

• First trimester infection is more likely to have congenital rubella, rare in third trimester
• Confirm vaccination status of the exposed individual, in which case they will be very low risk

Vaccination

• Live attenuated vaccine is included in MMR at 12-15 months and 4-6 years
• Vaccine is 95% effective
• Should revaccinate most young women