Author(s): Michelle Morales, Tatiana Lanzieri, Susan Reef

Infectious Agent

Rubella is a spherical, positive-sense, single-stranded RNA virus of the family Matonaviridae, genus Rubivirus.

Transmission

Rubella virus is transmitted through person-to-person contact or droplets shed from the respiratory secretions of infected people. People can shed virus from 7 days before the onset of the rash to ≈5–7 days after rash onset. Transmission from mother to fetus also can occur, with the highest risk for congenital rubella syndrome (CRS) if infection occurs in the first trimester. Infants with CRS can transmit virus for ≤1 year after they are born.

Epidemiology

In 2015, the World Health Organization Region of the Americas became the first in the world to be declared free of endemic rubella virus transmission. Rubella virus continues to circulate widely, however, especially in Africa, East Asia, and South Asia; ≈49,000 cases were reported worldwide in 2019, and ≈10,000 cases were reported in 2020. Globally, >100,000 infants are born each year with CRS; >80% are born in Africa and some countries in South and Southeast Asia. In the United States, endemic rubella virus transmission was interrupted in 2001 and elimination verified in 2004, but imported cases of rubella and CRS continue to occur. During 2016–2019, a median of 5 (range, 1–7) imported rubella cases were reported annually in the United States, and 8 CRS cases were reported during the same period.

Clinical Presentation

The average incubation period is 14 days (range 12–23 days). Rubella usually presents with generalized lymphadenopathy, slight or no fever, and a mild, nonspecific, maculopapular, generalized rash that lasts up to 3 days. The rash usually starts on the face, becoming generalized within 24 hours. Appearance of the rash can sometimes be preceded by anorexia, mild conjunctivitis, low-grade fever, malaise, runny nose, and sore throat. Adolescents and adults, especially women, also can present with transient arthritis. Rare complications include encephalitis and thrombocytopenic purpura, but ≈25%–50% of infections are asymptomatic. Infection during early pregnancy can lead to miscarriage, fetal death, or an infant born with CRS, a constellation of birth defects.

Diagnosis

Clinical diagnosis of rubella virus is unreliable and should not be considered in assessing immune status; ≤50% of all infections are subclinical or unapparent. Many rubella infections are not recognized because the rash resembles many other rash illnesses.

Diagnosis is based on serologic demonstration of specific rubella IgM or significant increase in rubella IgG in acute- and convalescent-phase specimens. Reverse transcription PCR (RT-PCR) can be used to detect virus infection; viral culture also is acceptable but is time consuming and expensive. Rubella is a nationally notifiable disease in the United States.

Treatment

Treatment of rubella involves supportive care. Counsel patients to isolate, and encourage household contacts to get tested and vaccinated.

Prevention

Unless contraindicated, vaccinate all travelers aged ≥12 months who do not have acceptable evidence of immunity to rubella (documented by ≥1 dose of rubella-containing vaccine on or after the first birthday, laboratory evidence of immunity, or birth before 1957) with measles-mumps-rubella (MMR) vaccine. Before departure from the United States, infants aged 6–11 months should receive 1 dose of MMR vaccine (for measles protection), and children aged ≥12 months and adults should receive 2 doses of MMR vaccine ≥28 days apart.

MMR vaccine is contraindicated during pregnancy. Advise pregnant people who do not have acceptable evidence of rubella immunity to avoid travel to countries where rubella is endemic or to areas with known rubella outbreaks, especially during the first 20 weeks of pregnancy. In addition, they should receive an MMR vaccination immediately postpartum. Ensure that all people of childbearing age and recent immigrants are up to date on immunization against rubella or have evidence of immunity to rubella, because these groups are at the greatest risk for maternal–fetal transmission of rubella virus, which can result in CRS.

CDC website: Rubella