Clinical Significance

Rubella is a member of the togaviridae family. Primary infections are generally mild, with symptoms such as a mild rash, low‑grade fever, and lymphadenopathy. In contrast, primary infections during pregnancy can pass transplacentally to the fetus and can lead to fetal death or congenital rubella syndrome (CRS); the risk of fetal infection is greatest during the first trimester of pregnancy. Babies born with CRS typically exhibit low birth weight, deafness, eye disease, mental retardation, and cardiac abnormalities.

A primary infection induces an IgM and an IgG response. Within 4–6 months, IgM levels become undetectable or very low. IgG decreases to low levels, but lasts indefinitely and confers lifelong immunity. A secondary infection exhibits a rising IgG antibody without significant levels of IgM.

Only 1 serological type of rubella virus is found in the population. Since the introduction of the rubella vaccine in the late 1960s, the incidence of CRS has dropped dramatically. However, outbreaks of rubella have still occurred and pose a potential risk to women of childbearing age. Immunity from the vaccination is shown to persist for more than 16 years.4 An antibody level of 10 IU/mL is thought to be protective.