Rubeola Antibody (Blood) Test

A rubeola antibody test looks for an antibody called measles-specific IgM in your blood. If you have been exposed to the rubeola virus, your body may have made this antibody. The rubeola virus causes measles, an extremely contagious disease. It is spread through the air in droplets after people cough or sneeze.

Thirty percent of people who catch the measles have complications. These include pneumonia, diarrhea, and ear infections that may cause permanent hearing loss. In rare cases, children may get encephalitis. This is a brain infection that can lead to intellectual disability and deafness.

Your doctor may also order tests for mumps or German measles (rubella).

This test may be done if you have been exposed to measles and haven't been vaccinated against the disease. If you are infected with the measles virus, you may not develop symptoms for 2 weeks.

This test may also be done if you have measles symptoms. These include:

• Rash that starts at the hairline and spreads down the face.
• Fever that slowly climbs to 103 °F (39.4 °C) or higher.
• Cough.
• Red, watery eyes (conjunctivitis).
• Runny nose.
• Diarrhea.

In general, there's nothing you have to do before this test, unless your doctor tells you to.

Be sure your doctor knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any drugs you may use.

The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand.

When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore.

Having a blood test with a needle carries some risks. These include:

• Bleeding.
• Infection.
• Bruising.
• Feeling lightheaded.

Test results may vary depending on your age, sex, health history, and other things. Your test results may be different depending on the lab used. They may not mean you have a problem. Ask your doctor what your test results mean for you.

Normal results are negative, meaning you don't have the measles-specific IgM antibody in your blood. A positive result means the antibodies have been found and it's likely you have a measles infection.

Timing is important for this test. Your body may not create much IgM antibody at the beginning of the infection, which would give a false-negative result. You may need to have the test again after the rash has been visible for several days. If you've recently been vaccinated against the measles, your IgM antibody level might be higher, giving a false-positive.