What is being tested?This test measures the presence of rubella
antibodies in the blood. Rubella antibodies are produced in response to an infection by the rubella
virus. There are two types of rubella antibodies:
IgM and
IgG. The first type to appear in the blood after exposure is the IgM rubella antibody. The level of this protein in the blood rises and peaks within about 7 to 10 days after infection and then tapers off over the next few weeks, except in an infected newborn, where it may be detected for several months to a year. The IgG rubella antibody takes a bit longer to appear than the IgM, but once it does, it stays in the bloodstream for life, providing protection against re-infection. The presence of IgM rubella antibodies in the blood can indicate a recent infection while the presence of IgG antibodies may indicate a recent or past rubella infection or that a rubella
vaccine (a measles, mumps, rubella vaccine) has been given and is providing adequate protection.
The rubella virus generally causes a mild infection marked by a fine red rash that appears on the face and neck and then travels to the trunk and limbs before disappearing a few days later. The virus is passed through nasal and throat secretions and can cause symptoms such as fever, enlarged lymph nodes, runny nose, red eyes, and joint pain. Symptoms may be so minimal, especially in children, that they are not perceived as being from a viral illness. In most patients, rubella goes away within a couple of days without any special medical treatment and causes no further health issues. The primary concern with rubella infection is when a pregnant woman contracts it for the first time during the first three months of her pregnancy. The developing fetus is the most vulnerable to the virus at this time and, if it is passed on to the fetus by the mother, it can cause miscarriage, stillbirth, and/or congenital rubella syndrome (CRS), a group of serious birth defects that will permanently affect the child. CRS can cause delayed development, mental retardation, deafness, cataracts, an abnormally small head, liver problems, and heart defects.
Because of the severe consequences for developing fetuses, a national campaign was started in 1969 to immunize all children in the United States and to work to eradicate rubella infection, first in the U.S. and then throughout the world. Prior to this time, rubella infections would emerge as cyclic outbreaks that lasted for several years. According to the Centers for Disease Control and Prevention (CDC), during the 1962-1965 rubella epidemic, 12.5 million cases of rubella occurred in the United States and there were 20,000 infants that were born with CRS. Due to vaccination efforts, these numbers have decreased drastically. In 2006, there were only 11 cases of rubella recorded in the United States and about half of the cases occurred in people who were born outside the U.S. (in countries without widespread vaccination programs). Each year since 2001, there have been fewer than 25 cases reported. The CDC now declares endemic rubella to be eradicated in the U.S., although the incidence continues to be monitored. People should not become complacent with this reduction, however, and the CDC cautions people to continue to have their children vaccinated. Anyone who has not received the vaccination as a child (and a few that have) may still be vulnerable to rubella infection.
