Rubella Virus

Snapshot

A 3-year-old girl is brought to the pediatrician’s office for a rash that began on the face and spread to the rest of her body. The rash is sometimes itchy. The girl also has a low-grade fever. She had just moved from South America to the US and had not received her childhood vaccinations. On physical exam, she has postauricular lymphadenopathy, a pink non-confluent maculopapular rash, and petechiae on her soft palate.

Introduction

Classification
- rubella virus
  - an enveloped, single-stranded, positive-sense RNA virus
  - icosahedral capsid
  - a togavirus
  - causes rubella (German 3-day measles)
  - transmission via respiratory secretions
Epidemiology
- incidence
  - decreased in the US due to vaccination
  - endemic in other parts of the world
- demographics
  - any age can be affected
- risk factors
  - lack of vaccination
  - travel to or from endemic areas
Pathogenesis
- the virus replicates in the upper respiratory tract and lymph nodes
- it then disseminates throughout the body
- can spread through the placenta to cause vertical transmission
  - may result in miscarriage or congenital rubella syndrome
Associated conditions
- congenital rubella syndrome
  - blueberry muffin appearance
    - dermal extramedullary hematopoiesis
  - cataracts
  - deafness
  - congenital heart disease (pulmonary artery stenosis or patent ductus arteriosus)
Prevention
- measles, mumps, and rubella (MMR) vaccine
  - given over 2 doses
Prognosis
infection may be asymptomatic but still contagious

Presentation

Symptoms
- low-grade fever
- polyarthritis and polyarthralgia
  - more common in adult females
  - fingers, wrists, and knees are most commonly involved
Physical exam
- lymphadenopathy before the rash
  - postauricular lymphadenopathy is classic
  - may also have posterior cervical and suboccipital lymphadenopathy
- fine, pink, non-confluent maculopapular rash
  - starts on face and spreads to trunk and extremities
  - may be itchy
  - desquamates
  - rash resolves in 3 days
- petechial rash on soft palate (Forschheimer spots)
orchitis

Studies

Labs
- detection of rubella-specific immunoglobulin M or G
- detection of virus on reverse transcriptase-polymerase chain reaction
Making the diagnosis
based on clinical presentation and confirmed with laboratory studies

Differential

Parvovirus B19 infection
- distinguishing factors
  - slapped cheek rash
  - maculopapular rash on trunk and limbs that does not spread from head/neck downward
Measles
- distinguishing factors
  - confluent maculopapular rash
coryza and Koplik spots

Treatment

Management approach
- mainstay of treatment is supportive care and prevention with vaccines
Conservative
- supportive care
  - indication
    - all patients
  - modalities
    - anti-pyretics
    - analgesics
hydration

Complications