Blood Tests

Routine blood tests will be done to find or rule out problems.

Antibody tests look for the body's defense against an infection. If a person has Lyme disease bacteria, their body will make certain antibodies. It takes about 4 weeks or more to detect these antibodies. Examples include:

• Antibody titer (ELISA or IFA) —This test measures the level of Lyme disease antibodies in the blood. If this test is positive, a Western Blot test can confirm the results.
• Western blot —This test detects antibodies to certain Lyme disease proteins in the blood.

Both of these tests can have false negative results. A false negative is when the test negative even though the person is infected. False positive results can also happen. A false positive is when the test is positive even though the person is not infected.

Tests may need to be repeated.

Antibody tests are often enough to make the diagnosis.

Supportive Tests

Additional tests may be done to look for Lyme disease. They may include:

Direct Detection Tests

These tests look for the bacteria in blood and other body fluids. Two main types are:

• Antigen detection tests —These look for a protein from Lyme disease bacteria. This test may detect Lyme disease in certain situations, such as:
  • If a person is taking antibiotics
  • During a later flare-up of symptoms
• Polymerase chain reaction (PCR) —This test finds specific parts of the Lyme bacteria.

Spinal Fluid Test

This test is done if there are nervous system symptoms. It is to see if Lyme disease is causing the symptoms. Spinal fluid is tested for bacteria using one of the tests listed above. It involves a lumbar puncture—a needle inserted into the spine to remove the fluid.

Electrocardiogram

Lyme disease can sometimes affect the heart. This test may be done if there is heart inflammation.

Skin biopsy

A skin biopsy takes and tests a sample of skin. It may be used to rule out causes of symptoms, such as cancer.