Lyme disease tests

A Lyme disease test is done to diagnose Lyme disease in people who have symptoms of Lyme disease. Symptoms may include:

• An expanding red rash with a pale center. This is sometimes called a "bull's-eye" rash.
• Extreme tiredness.
• Fever.
• Headache and stiff neck.
• Muscle and joint pain.

Symptoms of chronic Lyme disease infection include joint pain, stiffness, and problems with the heart, brain, or nerves.

Testing is most accurate when you have risk factors for Lyme disease or symptoms of the disease.

A health professional uses a needle to take a blood sample, usually from the arm.

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

Test results are usually available in 1 to 2 weeks.

An antibody test checks to see if you've had an infection from a bacteria that causes Lyme disease.

• A normal (negative) test means that no Lyme disease antibodies are found.
• An abnormal (positive) test means that Lyme disease antibodies are found.

The polymerase chain reaction (PCR) test may be done to confirm a Lyme infection if you have a positive antibody test result.

• A negative PCR test means the test didn't detect Lyme disease bacteria DNA.
• A positive PCR test means the test detected Lyme disease bacteria DNA.

Normal (negative) values

A normal, or negative, test for Lyme disease can mean one of the following:

• You do not have Lyme disease. A negative PCR test usually means that you do not have a Lyme disease infection.
• You have Lyme disease but it does not show up on the test (false-negative). This is more likely with the antibody tests than with PCR.

Abnormal (positive) values

An abnormal, or positive, test for Lyme disease can mean one of the following:

• If antibodies are found, you may either have Lyme disease now or had the illness in the past. Once you have a Lyme disease infection, antibodies to the bacteria will usually stay in your body for the rest of your life.
• If Lyme disease bacteria DNA is found, you probably have an active Lyme disease infection.
• The result is a false-positive. Sometimes an antibody test for Lyme disease finds antibodies to other bacteria.