Rubella

Maternal and Fetal Risks

Rubella (German measles or “third disease”) is an exanthematous disease caused by a single-stranded RNA virus of the togavirus family. Like measles, rubella is acquired via respiratory droplet exposure. After a 2- to 3-week incubation period, symptomatic patients develop a rash that spreads from the face to the trunk and extremities, lasting about 3 days. Fever, arthralgias, and postauricular, posterior cervical, and suboccipital lymphadenopathy are characteristic. Severe complications such as encephalitis, bleeding diathesis, and arthritis are rare. Overt clinical symptoms occur in only 50–75% of rubella-infected patients, and thus clinical history is not a useful marker of prior illness.

Rubella infection is usually a mild illness in both adults and children. However, fetal infection may be devastating. Congenital rubella syndrome (CRS) may produce transient abnormalities, including purpura, splenomegaly, jaundice, meningoencephalitis, and thrombocytopenia, or permanent anomalies such as cataracts, glaucoma, heart disease, deafness, microcephaly, and mental retardation. Long-term sequelae might include diabetes, thyroid abnormalities, precocious puberty, and progressive rubella panencephalitis. Defects involving virtually every organ have been reported (Table 26.1). A 50-year follow-up of 40 survivors of CRS born between 1939 and 1943 revealed that all had hearing impairment; 23 had eye defects related to the rubella.

The results of one large survey of maternal rubella infection in pregnancy are summarized in Table 26.2. The rate of fetal infection is highest at 11 weeks and < 36 weeks. However, the overall rate of congenital defects is greatest in the first trimester (90%) and declines steadily in the second and third trimesters

Rubella vaccine became available in the United States in 1969. Vaccination given as a trivalent preparation of measles, mumps, and rubella (MMR) vaccine produces long-term immunity in 95% of vaccines. The rates of rubella dropped precipitously after introduction of the vaccine. Ten years later, the annual incidence of rubella infections, including CRS, had decreased by 99.6%. In 2012, the Centers for Disease Control and Prevention (CDC) declared that rubella and congenital rubella syndrome were eliminated from the United States. Still, between 2005 and 2011 between 4 and 18 cases were reported each year. Of 67 rubella cases reported, 28 cases were known importations. These sporadic cases underscore the need to be aware of and vigilant for CRS and the possibility for continued cases from regions with incomplete immunization programs.