Clinical and Interpretive

This assay is used for the determination of immune status to the rubella virus.

Rubella (German or 3-day measles) is a member of the togavirus family and humans remain the only natural host for this virus. Transmission is typically through inhalation of infectious aerosolized respiratory droplets and the incubation period following exposure can range from 12 to 23 days. Infection is generally mild and self-limited, and is characterized by a maculopapular rash beginning on the face and spreading to the trunk and extremities, fever, malaise, and lymphadenopathy.

Primary in utero rubella infections can lead to severe sequelae for the fetus, particularly if infection occurs within the first 4 months of gestation. Congenital rubella syndrome is often associated with hearing loss, cardiovascular and ocular defects.

The United States 2-dose measles, mumps, rubella (MMR) vaccination program, which calls for vaccination of all children, leads to seroconversion in 95% of children following the first dose. A total of 4 cases of rubella were reported to the CDC in 2011 without any cases of congenital rubella syndrome. Due to the success of the national vaccination program, rubella is no longer considered endemic in the United States. However, immunity may wane with age as approximately 80% to 90% of adults will show serologic evidence of immunity to rubella.

IgG-class antibodies to rubella virus may be present in serum specimens from individuals who have received blood products within the past several months, but who have not been immunized or experienced past infection with this virus.

Serum samples drawn early during acute phase of infection may be negative for IgG-class antibodies to this virus.

The presence of antirubella-IgG antibodies does not exclude the possibility of a recent or ongoing infection. Testing for IgM-class antibodies to rubella should be performed at a state health laboratory or at the CDC if the clinical presentation is suggestive of acute rubella infection.