A Lyme disease antibody test is used to determine if you have been infected with Borrelia burgdorferi, the bacterium that causes Lyme disease. Lyme disease antibody tests are conducted with a routine blood draw.
Lyme disease is transmitted to humans through ticks that are infected with Borrelia burgdorferi. Symptoms of Lyme disease include:
- joint pain
- bull’s-eye–shaped skin rash
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 “bulls-eye” rash pattern around a tick bite. Your doctor will use the results of your 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 bacteria, viruses, fungi, and chemicals.
Your body produces antibodies if you are infected with Borrelia burgdorferi, the bacterium that causes Lyme disease. These Lyme disease-specific antibodies will be present in your blood and your test will be positive.
If you have never been exposed to Borrelia burgdorferi, you will not have any Lyme disease antibodies in your bloodstream. In this case, your test will be negative.
You may test negative for Lyme disease in the early days and weeks after 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 four weeks after infection.
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. The technician will draw blood 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 technician will collect the blood sample 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 a remote possibility, but is an increased risk if you take blood-thinning medications or certain anti-inflammatory drugs, such as:
Infection at the puncture site is also possible, but unlikely. Keep the bandage in place until all bleeding has stopped and keep the area clean. Some people feel light-headed 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.
Lyme disease antibodies can be detected through a series of tests at a laboratory:
- IgM antibody: a large molecule present in the blood when you have an infection
- IgG antibody: another molecule that fights bacterial infection
- ELISA: stands for “enzyme-linked immunosorbent assay.” ELISA tests detect antibodies in your bloodstream.
- Western blot: a follow-up test that detects proteins and antibodies in the blood
The IgM and IgG tests are performed first. If you test positive for these antibodies, it is likely that you have or had Lyme disease. A positive result on the ELISA test means Lyme disease is likely, but must be confirmed with a Western blot. The Western blot test is the definitive diagnosis for Lyme disease.
Once you have been infected with 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 have tested positive for Lyme disease.