Rubella

Rubella (German measles) is an infectious disease caused by the rubella virus and transmitted via airborne droplets or transplacentally (see “Congenital rubella syndrome”). Since the introduction of the measles, mumps, and rubella (MMR) vaccine, rubella is relatively rare. The clinical course is mild, characterized by an erythematous maculopapular rash that typically starts on the face and progresses distally. The rash may be preceded by nonspecific flu-like symptoms and postauricular and/or suboccipital lymphadenopathy. The combination of RT-PCR and serology for rubella-specific IgM antibodies is preferred to confirm active disease. Treatment is supportive and isolation is recommended. Immunization with the MMR vaccine or MMRV vaccine is recommended for all children and adults without evidence of immunity.

This article pertains to rubella acquired postnatally; congenital rubella syndrome is addressed separately.

• A rare disease in the US following the implementation of the MMR vaccine
• Risk factors: See “Risk factors for measles, mumps, and/or rubella.”

Epidemiological data refers to the US, unless otherwise specified.

• Pathogen
  • Rubella virus, an RNA virus of the family Matonaviridae
  • Prior to 2019, the rubella virus was classified as the sole member of the Rubivirus genus in the Togaviridae family. ^[1]
  • Humans are the only hosts.
• Route of transmission
  • Respiratory droplets or transplacental
  • Infectivity: 7 days prior to and 7 days following the appearance of an exanthem
  • Low infectivity and virulence
• Incubation period: 2–3 weeks after infection

Patients with rubella infection are asymptomatic in ∼ 50% of cases. Young children have a far milder course than older children and adults; the latter group often presents with prodromal symptoms, other systemic complaints (e.g., arthritis), and a longer duration of infection.

Prodromal phase

• Duration: 1–5 days
• Findings
  • Post-auricular and suboccipital lymphadenopathy and occasionally splenomegaly
  • Mild and nonspecific symptoms such as low-grade fever; , mild sore throat, cough, conjunctivitis, headache, and aching joints
  • Forchheimer sign: enanthem of the soft palate

Exanthem phase

• Duration: lasts 2–3 days
• Findings
  • Fine, nonconfluent, pink maculopapular rash
    • Begins at the head, primarily behind the ears, extends to the trunk and extremities, sparing palms and soles
    • Rash may be itchy in adults
  • Polyarthritis

Clinical features of rubella are typically nonspecific; ; consider acute infection in an unvaccinated patient with a febrile rash.

Infection control ^[2][3][4]

• Isolate patient and institute standard precautions and droplet precautions.
• Ensure that only health care professionals with evidence of rubella immunity provide direct care to the patient.
• Notify the local health department immediately of a suspected case.

Rubella is a nationally notifiable disease in the US; immediately report all suspected and confirmed cases to the local health department.

Diagnostics ^[2][3][4]

Obtain and interpret diagnostic studies in all patients in coordination with the health department.

Studies

• All patients: serology for rubella-specific IgM and IgG antibodies
• Patients presenting ≤ 7 days (ideally ≤ 3 days) after rash onset: ^[4]
  • RT-PCR of a nasopharyngeal or throat swab
  • If presenting close to day 7 after rash onset, also consider RT-PCR of a urine sample. ^[4]

Interpretation of results

• Confirmatory results include any of the following:
  • Positive RT-PCR or viral culture ^[4]
  • Positive IgM antibodies ^[4]
  • A 4-fold increase in IgG antibodies seen on two serum samples taken ∼ 2 weeks apart, starting from the onset of symptoms ^[4]
• Results that cannot rule out acute infection include:
  • A single negative IgM test within the first 5 days of rash onset (in this case, repeat IgM test) ^[5]
  • A single negative IgG test

RT-PCR with serology for rubella-specific IgM antibodies is preferred to confirm acute rubella infection. RT-PCR should be collected as soon as possible and within 7 days of rash onset. ^[2][3]

Further management ^[6]

• Supportive therapy, e.g.:
  • Fever: supportive care for pediatric fever
  • Severe pruritus: antihistamines
  • Severe polyarthritis: rest and NSAIDs
• For treatment of congenital rubella syndrome and seronegative women following exposure to rubella virus, see “Congenital rubella syndrome.”
• Instruct patients and exposed contacts on isolation precautions; see “Exposure control for rubella.”

• Differential diagnoses of pediatric rashes

The differential diagnoses listed here are not exhaustive.

• Chronic arthritis (especially women)
• Thrombocytopenic purpura
• Rubella during pregnancy (TORCH infection): congenital rubella syndrome
• Rare: rubella encephalitis, bronchitis, otitis, myocarditis, pericarditis

We list the most important complications. The selection is not exhaustive.

• The disease usually has a benign course and the exanthem disappears rapidly.
• Joint pain may persist for several weeks; arthralgia may persist up to a month in adults.

Vaccination ^[7][8][9]

Administer a live attenuated rubella vaccine; (i.e., MMR vaccine, MMRV vaccine) according to the ACIP immunization schedule. See the following:

• Immunizations for measles, mumps, and rubella
• ACIP immunization schedule
• Contraindications to live vaccines (e.g., pregnancy, immunocompromise)

Evidence of immunity to rubella ^[5][10]

• See “Indications to test for immunity to rubella” and “Evidence of immunity to measles, mumps, and/or rubella.”
• If laboratory evidence of immunity to rubella is required, perform serologic testing. ^[5][10]
  • IgG measurement by enzyme immunoassay is preferred.
  • A rubella IgG titer > 10 IU/mL indicates immunity to rubella. ^[5]

Women of reproductive age without evidence of immunity to rubella should be vaccinated prior to pregnancy to prevent congenital rubella syndrome. ^[11]

Exposure control for rubella ^[12]

• Suspected and confirmed rubella
  • Hospitalized patients: Initiate standard precautions and droplet precautions.
  • Isolate for 7 days from rash onset to prevent further transmission. ^[12]
• Exposed contacts without evidence of immunity to rubella
  • Women of reproductive age: Obtain pregancy test.
  • Pregnant individuals: Promptly obtain serology for rubella-specific IgM and IgG antibodies; follow up with health department.
  • Individuals without contraindications to live vaccines: Offer MMR vaccine to protect from future exposures. ^[3][13]
  • Isolation
    • Health care workers: Exclude from work from day 7 after first exposure until day 23 after last exposure. ^[12]
    • Others: Refer to health department guidance.