RUBELLA (GERMAN MEASLES)

Rubella, also known as German Measles, is an acute viral disease that can affect susceptible persons of any age.

Although rubella is generally a mild rash illness, if contracted in the early months of pregnancy it is associated with a high rate of foetal loss or a constellation of birth defects, known as congenital rubella syndrome (CRS).

Rubella occurs worldwide, and the risk of exposure to rubella outside the United States can be high. Although more than half of all countries now use rubella vaccine, rubella still remains a common disease in many parts of the world.

Clinical Presentation

Rubella usually presents as a nonspecific maculopapular rash lasting 3 days or fewer (hence the term "3-day measles") with generalised lymphadenopathy, particularly of the postauricular, suboccipital and posterior cervical lymph nodes.

However, asymptomatic infections are common: up to 50% of infections occur without rash.

In adults or adolescents, the rash may be preceded by a 1- to 5-day prodrome of low-grade fever, headache, malaise, anorexia, mild conjunctivitis, coryza, sore throat, and lymphadenopathy.

Prevention

Rubella vaccine, which contains live, attenuated rubella virus, is available as a single-antigen preparation or combined with live, attenuated measles or mumps vaccines, or both. Combined measles, mumps, and rubella (MMR) vaccine is recommended whenever one or more of the individual components is indicated and is the most common vaccine formulation available in the United States.

Although vaccination against measles, mumps, or rubella is not a requirement for entry into any country (including the United States), persons travelling or living abroad should ensure that they are immune to all three diseases. Immunity to rubella is particularly important for health-care providers and women of childbearing age. Persons can be considered immune to rubella if they have documentation of receipt of one or more doses of a rubella-containing vaccine on or after their first birthday, or laboratory evidence of rubella immunity. Birth before 1957 provides only presumptive evidence of rubella immunity and does not guarantee that a person is immune. Rubella can occur in susceptible persons born before 1957, and CRS can occur in the offspring of women born before 1957 infected with rubella during pregnancy. The Advisory Committee on Immunisation Practices (ACIP) recommends that birth before 1957 not be accepted as evidence of rubella immunity for women who might become pregnant. A clinical diagnosis of rubella is unreliable and should not be considered in assessing immune status. Because many rash illnesses can mimic rubella infection and many rubella infections are unrecognised, the only reliable evidence of previous rubella infection is the presence of serum rubella IgG.

According to the routine childhood immunisation schedule (Table 8-2), the first dose of MMR should be routinely administered to infants 12-15 months of age. A single dose of MMR vaccine induces antibody formation to all three viruses in at least 95% of susceptible persons vaccinated at 12 months of age. The second dose should be separated from the first dose by a minimum of 28 days.

Health-care providers who treat women of childbearing age should routinely determine their rubella immunity status and vaccinate those who are susceptible and not pregnant. Proof of immunity can be either a verified record of vaccination or a positive IgG antibody serologic test. Rubella-susceptible women who 1) do not report being pregnant, 2) are not likely to become pregnant within 1 month, and 3) have no other contraindicating conditions should be vaccinated. Before vaccination, each patient should be counseled to avoid pregnancy for 1 month after vaccination because of the theoretical risk for vaccine virus affecting the foetus. Because routine pregnancy screening is not recommended before rubella vaccination, patients should be counseled regarding the theoretical risk to the foetus from inadvertent vaccination of a pregnant woman.