A Lyme disease blood test is used to determine if you have contracted Borrelia burgdorferi (B. burgdorferi), the bacterium that causes Lyme disease. Lyme disease tests are conducted with a routine blood draw.
While there are other species of Borrelia that cause Lyme disease, B. burgdorferi is the most common cause in the United States. Most antibody tests in the United States only test for B. burgdorferi, but other species-specific tests are available depending on a person’s travel history.
Lyme disease is transmitted to humans through ticks that are infected with Borrelia.
Symptoms of Lyme disease include:
- joint pain
- skin rash in the shape of a bull’s-eye
Untreated, Lyme disease can affect your heart and nervous system. Symptoms of advanced Lyme disease can include:
- loss of muscle tone in the face
- memory loss
- tingling in your hands and feet
- heart palpitations
- irregular heartbeat
- shortness of breath
Lyme disease can be difficult to diagnose. Ticks are very small, and the bites are not always noticeable. Symptoms of the disease can vary from person to person. Not everyone experiences the classic “bull’s-eye” rash pattern around a tick bite.
It should be noted that testing is not always required to make a diagnosis. For people with a classic bulls-eye rash (Erythema migrans) living in a high risk area, testing is not recommended for diagnosis.
Your doctor will use the results of a Lyme disease antibody test, along with the report of your symptoms, to confirm a diagnosis.
Antibodies are proteins your body makes in response to foreign or harmful substances called antigens. Common antigens include:
Your body produces antibodies if you have contracted B. burgdorferi. These Lyme disease-specific antibodies will be present in your blood, and your test will be positive if you have the bacterial infection.
If you have never been exposed to B. burgdorferi, you will not have any Lyme disease antibodies in your bloodstream. In this case, your test will be negative.
However, there is a possibility of false positive results due to potential test cross-reactivity with other diseases including syphilis, autoimmune diseases, and Epstein Barr virus.
However, you may test negative for Lyme disease in the early days and weeks after contracting the infection. This is because your body has not yet produced a significant number of antibodies. You will usually test positive for Lyme disease starting at about 2 to 4 weeks after acquiring an infection.
A series of laboratory tests can detect Lyme disease antibodies. These tests include:
- ELISA: stands for “enzyme-linked immunosorbent assay,” which detects antibodies in your bloodstream
- IgM antibody test: tests for the IgM antibody present in the blood when you have an infection
- IgG antibody test: tests for the IgG antibody that fights bacterial infection
- Western blot: a follow-up test that detects proteins and antibodies in the blood (the Western blot is only meaningful during the first 4 weeks of an infection)
The ELISA test is performed first. If results are positive or equivocal, a second test, IgM/IgG immunoassay or immunoblot is performed. It is no longer recommended to check IgM or IgG antibodies without a prior immunoassay.
The Lyme disease antibody test requires no advance preparation. A lab technician will swab the inside of your elbow with an antiseptic before drawing your blood. Your blood will be drawn from a vein in your arm using a small needle.
The blood draw should not be painful, though you might feel a slight prick when the needle is inserted into your vein.
The blood sample will be collected in a vial. The puncture site will be bandaged, if needed, after the needle is removed. After the blood draw, you are free to go home.
There are very few risks associated with the Lyme disease antibody test. Excessive bleeding is possible, but there may be an increased risk if you take blood thinning medications or certain anti-inflammatory drugs like:
Infection at the puncture site is also possible, but it’s unlikely. Keep the bandage in place until all bleeding has stopped and keep the area clean. Some people feel lightheaded after having blood drawn. Let the technician know if this is the case. You might be asked to sit for a few minutes before going home.
Once you have Lyme disease, the antibodies remain in your blood. So even after you have been treated for the disease, you might still have positive blood tests.
Lyme disease is treated with antibiotics. Your doctor will discuss your course of treatment in detail if you test positive for the bacterial infection.