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Congenital Rubella

by Mary T. Caserta, MD

(See Rubella.)

Congenital rubella is a viral infection acquired from the mother during pregnancy. Signs are multiple congenital anomalies that can result in fetal death. Diagnosis is by serology and viral culture. There is no specific treatment. Prevention is by routine vaccination.

Congenital rubella typically results from a primary maternal infection. Congenital rubella is rare in the US.

Rubella is believed to invade the upper respiratory tract, with subsequent viremia and dissemination of virus to different sites, including the placenta. The fetus is at highest risk of developmental abnormalities when infected during the first 16 wk of gestation, particularly the first 8 to 10 wk. Early in gestation, the virus is thought to establish a chronic intrauterine infection. Its effects include endothelial damage to blood vessels, direct cytolysis of cells, and disruption of cellular mitosis.

Symptoms and Signs

Rubella in a pregnant woman may be asymptomatic or characterized by upper respiratory tract symptoms, mild fever, conjunctivitis, lymphadenopathy (especially in the suboccipital and posterior auricular areas), and a maculopapular rash. This illness may be followed by joint symptoms.

In the fetus there may be no effects, death in utero, or multiple anomalies referred to as congenital rubella syndrome (CRS). The most frequent abnormalities include intrauterine growth restriction, microcephaly, meningoencephalitis, cataracts, retinopathy, hearing loss, cardiac defects (patent ductus arteriosus and pulmonary artery stenosis), hepatosplenomegaly, and bone radiolucencies. Others are thrombocytopenia with purpura, dermal erythropoiesis resulting in bluish red skin lesions, adenopathy, hemolytic anemia, and interstitial pneumonia. Close observation is needed to detect subsequent hearing loss, intellectual disability, abnormal behavior, endocrinopathies (eg, diabetes mellitus), or a rare progressive encephalitis. Infants with congenital rubella infections may develop immune deficiencies such as hypogammaglobulinemia.

Diagnosis

  • Maternal serum rubella titers

  • Viral detection via culture and/or reverse transcriptase–PCR (RT-PCR) of amniotic fluid, nose, throat (preferred), urine, CSF, or blood specimens

  • Infant antibody titers (measured serially) and viral detection as above

Pregnant women routinely have a serum rubella IgG titer measured early in pregnancy. Titer is repeated in seronegative women who develop symptoms or signs of rubella; diagnosis is made by a positive serologic test for IgM antibody, IgG seroconversion, or a 4-fold rise between acute and convalescent IgG titers. Virus may be cultured from nasopharyngeal swabs but is difficult to cultivate. RT-PCR can be used to confirm culture results or detect viral RNA directly in patient specimens as well as allow for genotyping and epidemiological tracking of wild-type rubella infections.

Infants suspected of having CRS should have antibody titers and specimens obtained for viral detection . Persistence of rubella-specific IgG in the infant after 6 to 12 mo suggests congenital infection. Detection of rubella-specific IgM antibodies generally also indicates rubella infection, but false-positive IgM results can occur. Specimens from the nasopharynx, urine, CSF, buffy coat, and conjunctiva from infants with CRS usually contain virus; samples from the nasopharynx usually offer the best sensitivity for culture, and the laboratory should be notified that rubella virus is suspected. In a few centers, diagnoses can be made prenatally by detecting the virus in amniotic fluid, detecting rubella-specific IgM in fetal blood, or applying RT-PCR techniques to fetal blood or chorionic villus biopsy specimens.

Other tests include a CBC with differential, CSF analysis, and x-ray examination of the bones to detect characteristic radiolucencies. Thorough ophthalmologic and cardiac evaluations are also useful.

Treatment

  • Counseling

  • Possibly immune globulin for the mother

No specific therapy is available for maternal or congenital rubella infection. Women exposed to rubella early in pregnancy should be informed of the potential risks to the fetus. Some experts recommend giving nonspecific immune globulin (0.55 mL/kg IM) for exposure early in pregnancy, but this treatment does not prevent infection, and the use of immune globulin should be considered only in women who decline pregnancy termination.

Prevention

Rubella can easily be prevented by vaccination. In the US, infants should receive vaccination for rubella together with measles and mumps vaccinations at 12 to 15 mo of age and again at entry to grade school or junior high school (see Table: Recommended Immunization Schedule for Ages 7–18 yr). Postpubertal females who are not known to be immune to rubella should be vaccinated. (C aution : Rubella vaccination is contraindicated in immunodeficient or pregnant women. ) After vaccination, women should be advised not to become pregnant for 28 days. Efforts should also be made to screen and vaccinate high-risk groups, such as hospital and child care workers, military recruits, recent immigrants, and college students. Women who are found to be susceptible during prenatal screening should be vaccinated after delivery and before hospital discharge. Theoretically, vaccination of nonimmune people exposed to rubella might prevent infection if done within 3 days of exposure, but this treatment has not proved to be beneficial.

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