What is a blood test for Lyme disease?
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 done with a routine blood draw. While there are other Borrelia species 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 based on a person’s travel history.
Lyme disease symptoms include:
- joint pain
- bull’s-eye rash
Without treatment, Lyme disease can affect the heart and nervous system. Symptoms of advanced Lyme disease can include:
- loss of muscle tone in the face
- memory loss
- tingling in the hands and feet
- heart palpitations
- irregular heartbeat
- difficulty breathing
Lyme disease can be difficult to diagnose. Ticks are very small and bites are not always noticeable. The symptoms of the disease can vary from person to person. Not everyone experiences the classic “bulls-eye” rash pattern around a tick bite.
It should be noted that tests are not always required to make a diagnosis. For people with a classic bull’s-eye rash (Erythema migrans) who live in a high-risk area, diagnostic testing is not recommended. Your doctor will use the results of a Lyme disease antibody test, along with a report of your symptoms, to confirm a diagnosis.
What are antibodies?
Antibodies are proteins that your body makes in response to foreign or harmful substances called antigens. Common antigens include:
- chemical products
Your body makes 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 the possibility of false positive results due to possible cross-reactivity of the test with other diseases, such as syphilis, autoimmune diseases and Epstein Barr virus. However, you can test negative for Lyme disease in the first days and weeks after becoming infected. This is because your body has not yet produced a significant amount of antibodies. Typically, you will test positive for Lyme disease starting about 2 to 4 weeks after getting an infection.
Tests for Lyme disease in the laboratory
A number of laboratory tests can detect antibodies to Lyme disease. These tests include:
- ELISA: stands for “enzyme-linked immunosorbent assay,” which detects antibodies in the 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 significant for the first 4 weeks of infection)
First, the ELISA test is performed. If the results are positive or equivocal, a second test, IgM/IgG immunoassay or immunoblotting, is performed. Testing for IgM or IgG antibodies without prior immunoassay is no longer recommended.
Lyme disease antibody test procedure
The Lyme disease antibody test requires no preparation. A lab technician will rub the inside of your elbow with an antiseptic before drawing your blood. Blood will be drawn from a vein in your arm with a small needle. The blood draw should not be painful, although you may feel a slight sting when the needle is inserted into your vein. The blood sample will be collected in a vial. The puncture site will be bandaged, if necessary after the needle is withdrawn. After the blood draw, you can go home.
Risks of a Lyme disease antibody test
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 medications such as:
Infection at the puncture site is also possible, but unlikely. Keep the bandage in place until all bleeding stops and keep the area clean. Some people feel dizzy after having their blood drawn. Inform the technician if this is the case. You may be asked to sit down for a few minutes before going home.