Rubella Test - IgG

The Rubella IgG test is a blood test that is used to detect IgG antibodies against the rubella virus. IgG antibodies are proteins produced by the immune system in response to past infections or vaccinations.

Rubella virus infection, also known as German measles, causes a mild disease with symptoms such as rash on the face and trunk, mild fever, malaise (a feeling of illness), and mild joint pain in children. In pregnant women, it can cause miscarriage, stillbirth, and congenital disabilities (birth defects) in the baby, together known as congenital rubella syndrome (CRS). The Rubella IgG test helps determine whether a person is immune to rubella, which is important for reducing the risk of rubella infection and congenital rubella syndrome during pregnancy.

The test is also known as the German measles immunity test, rubella antibodies (IgG) test, German measles antibodies test, rubella serology test, or rubella immunity test.

The Rubella IgG test is advised if you are experiencing the following symptoms of rubella infection:

• Fever, general discomfort, a runny nose, and headache, followed by a rash
• Muscle or joint pain
• Eye inflammation
• Bruising (rarely)

The test is considered essential in pregnant women and newborns as the virus may cause congenital rubella syndrome (CRS), which can lead to miscarriage, foetal death, or affect multiple organ systems of the foetus. The most common defects caused by CRS in babies include hearing problems, eye defects like cataracts, and cardiac defects. Babies that survive infancy may have serious disabilities (e.g., deafness), autoimmune conditions, and developmental delays. Infants born with rubella infection may continue to release large amounts of the virus through body fluids for up to one year, increasing the risk of rubella outbreaks.

The rubella blood test does not directly diagnose diseases, but can help assess immunity status of individuals and support the evaluation of a few conditions that can occur due to rubella, including:

• Pregnancy-related complications in the mother: Miscarriage and stillbirth may occur if rubella infection develops during pregnancy.
• Congenital rubella syndrome-related complications in newborns: Hearing loss, haemolytic anaemia (anaemia caused by destruction of red blood cells), low birth weight, eye defects (such as cataracts and congenital glaucoma), hepatosplenomegaly (enlargement of the liver and spleen), and heart defects are some of the complications seen in newborns with CRS.
• Long-term complications in children with CRS: Developmental delays and certain autoimmune conditions, such as type 1 diabetes and thyroiditis, may occur later in childhood.

What to Expect Before the Rubella Test - IgG Test

No fasting is required for a standalone Rubella Test - IgG test. You can eat and drink normally. However, if it is part of a broader package that includes fasting tests, your doctor may advise fasting for 8-12 hours. Avoid strenuous exercise for 24 hours before the test, as intense physical activity can temporarily raise Rubella Test - IgG levels and affect interpretation. Always inform your doctor about any ongoing medications.

What to Expect During the Blood Collection

A phlebotomist cleans the skin with an antiseptic, then places an elastic band around your upper arm to make the veins easier to access. A small needle is inserted into the vein; you may feel a brief pinch. Blood is collected into a labelled tube in under a minute.

What to Expect After the Rubella Test - IgG Test

A small cotton swab and bandage are placed over the site to stop any minor bleeding. You can return to normal activities immediately. Minor bruising is normal and disappears quickly. If dizzy, sit and rest for a few minutes.

In the Rubella IgG test, the primary parameter measured is:

• Levels of IgG antibody against the rubella virus in the blood.

The Rubella IgG test normal range is indicated in the table below. 

Note:

• The normal range may vary slightly depending on the laboratory and individual health conditions.

The table below provides a general interpretation of the Rubella IgG test results based on IgG level.

Note: The interpretation of rubella laboratory results must always consider the patient’s relevant past medical history and symptoms.

Like any other medical test, this test also has some risks and limitations.

Risks:

• The Rubella IgG test is generally safe. You may feel slight pain, bruising, or discomfort when the needle is inserted. However, risks like mild bruising are rare and quickly resolve on their own.

Limitations:

• If rubella IgG is not detected at the initial test, the test may need to be repeated.
• A single positive result may not be enough for diagnosis. An additional test, known as the rubella IgG antibody avidity test, can be used to distinguish between recent and more distant exposure to rubella.

Depending on your symptoms and results, your doctor may recommend additional tests to better understand your condition. These include:

• Rubella IgM test
• Rubella IgG antibody avidity test
• Rubella RT-PCR assay 
• TORCH (toxoplasmosis, rubella, cytomegalovirus, herpes simplex, and HIV) screen test
• Parvovirus IgG test
• Parvovirus IgM test
• NS1 antigen test for dengue