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What is Rubella test?

Rubella test measures the number of rubella antibodies in blood to determine the presence or absence of immunity against rubella virus. There are two types of rubella antibodies, IgM and IgG.

  • IgM appears first in the bloodstream after exposure to rubella virus. IgM antibodies reach the maximum level by 7-10 days after infection and its levels go down in the next few weeks. However, it may be present in blood and can be detected for about several months to a year in infected newborns
  • IgG antibodies take a long time to appear. But once it does, it stays for life and prevents a rubella infection in future

Rubella test is also known as 3-day measles test, rubella antibody test and German measles test.

Rubella is a contagious disease with a quick onset. It spreads through cough, sneeze and spit of the infected person. Although rubella is also called German measles, it is not similar to measles. Rubella virus is different from measles virus. Unlike the rashes caused by measles, rubella rashes are milder and last for a shorter period. Rubella is not a life-threatening condition though it can lead to severe manifestations in adults. Also, this virus can easily pass the placental barrier in pregnant women and may lead to congenital defects or miscarriage.  

  1. Why is Rubella test performed?
  2. How do you prepare for Rubella test?
  3. How is Rubella test performed?
  4. What do Rubella test results mean?

Rubella test is recommended as a part of the prenatal examination in women during early pregnancy or in those who are planning to conceive. This test is also ordered in pregnant women with symptoms such as:

Women, who are not previously immunised against rubella virus, can transmit the virus to their baby if they get infected during pregnancy, which causes serious congenital disabilities or miscarriage. The most commonly observed congenital disabilities due to rubella virus include:

Other complications observed in such babies include thyroid problems and hormonal issues, inflammation of lungs, glaucoma and brain damage. Therefore, a rubella test is also ordered in babies born with these defects or babies whose mothers were infected with rubella during pregnancy.

Although the symptoms can be treated in babies born with congenital disabilities due to rubella virus, chronic rubella syndrome cannot be treated. Therefore, it is essential for every pregnant woman to undergo a rubella test and determine the presence of rubella antibodies in their blood so they can be vaccinated on time. However, rubella vaccination is not required in women who have had rubella in the past as they have acquired natural immunity against rubella virus and will not be infected with it again. Also, vaccination is not recommended for women who are already pregnant.

No special preparations are recommended for this test. However, you should inform your doctor about any prescription or non-prescription medications, including vitamins, supplements and natural products like herbal medicines that you may be taking before the test.

For this test, a blood sample will be collected from a vein in your hand or arm with the help of a needle. In a baby, blood is withdrawn from the heel, whereas it is collected from the umbilical cord in a newborn. Some individuals may feel a slight discomfort like a stinging sensation or pain during the test, which would persist for a while after the test.          

Some risks associated with blood sample collection include bleeding, infection, feeling lightheaded and bruising.

Rubella test results vary based on the age group of individuals. Normal and abnormal results of rubella test are as follows:

Normal results:

  • Absence of both IgM and IgG antibodies indicates no recent or past exposure to rubella virus in children and adults
  • Presence of only IgG antibodies with no IgM antibodies in children and adults indicates a history of rubella virus infection or immunisation with rubella vaccine
  • Presence of IgG antibodies in newborns indicates the transfer of antibodies from the mother to the baby. Such babes are thus immunised for about 6-12 months
  • Absence of both IgM and IgG antibodies in newborns, children and adults indicates the absence of current or recent rubella infection or infections in the past. It also indicates a lack of immunisation against rubella virus

Abnormal results:

  • Presence of IgM antibodies in newborns indicates recent post-natal or congenital infections
  • Presence of IgM antibodies in adults and children (with or without the presence of IgG antibodies) indicates recent infection with rubella virus

A false-positive test for IgM rubella antibodies may be observed in individuals infected with other viruses. Therefore, your doctor may recommend IgG baseline test and an IgG test between 7-21 days of infection. A significant increase in IgG antibodies helps to confirm the diagnosis.

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor. 

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References

  1. University of Rochester Medical Center Rochester, NY. [Internet] Rubella
  2. Center for Disease Control and Prevention [internet], Atlanta (GA): US Department of Health and Human Services; Epidemiology and Prevention of Vaccine-Preventable Diseases
  3. World Health Organization [Internet]. Geneva (SUI): World Health Organization; Manual for the laboratory diagnosis of measles and rubella virus infection.
  4. Center for Disease Control and Prevention [internet], Atlanta (GA): US Department of Health and Human Services; Manual for the Surveillance of Vaccine-Preventable Diseases
  5. Center for Disease Control and Prevention [internet], Atlanta (GA): US Department of Health and Human Services; Pregnancy and Rubella.