The only way to diagnose Lyme disease is through a blood test. There are several different tests that can be used but some have disadvantages.
Test to detect antibodies to Lyme
When your body is infected by a bacteria or foreign invader, your immune system creates antibodies to combat it. Antibody level tests are called “indirect tests” because they measure the body’s response to infection rather than the presence of the bacteria themselves.
The disadvantage to these tests is that for the first 4-6 weeks after exposure, most people have not created the antibody response that the test will pick up. In cases where the suspicion of Lyme disease is high (tick bite, rash or exposure), treatment should be started immediately and not delayed while waiting for a positive test result. The longer Lyme disease is allowed to infect without treatment it becomes much more difficult to treat.
There are two antibody tests currently used to diagnose Lyme disease: the western blot and the ELISA. A common practice is for physicians to first order an ELISA to check for the disease and then go on to order western blot to confirm the disease. The disadvantage to current ELISA testing is that they are not sensitive enough and may possibly miss over 50% of the positive findings. This makes the western blot the best antibody test to use for Lyme diagnosis.
The result from the western blot looks like a bar code (see above). The band pattern produced by the test is compared to a template pattern that represents known cases of Lyme disease. Depending on your bands and where they are in the pattern, then it is reported as positive. Some of the bands have more weight and significance than other bands and therefore, your physician may diagnose you with Lyme disease even if your western blot band pattern does not meet the Centers for Disease Control and Prevention (CDC) guidelines for surveillance purposes.
To add to the confusion, laboratories do not all use the same methods and criteria, so you can have a positive result from one laboratory and a negative result from another.
Other tests
There are 2 other tests that can be used to diagnose Lyme disease: Polymerase chain reaction (PCR) and antigen detection tests. PCR functions by multiplying a specific portion of DNA from the Lyme bacteria, allowing it to be detected. PCR’s advantage is that it is highly accurate. When the Lyme DNA is detected, it will accurately report Lyme positive cases where a false negative had previously been reported by other testing methods. Laboratory tests to detect antigens look for a unique Lyme protein in bodily fluid (e.g. blood, urine, joint fluid). It is common for people whose indirect tests that came back as negative, come back as positive on antigen detection tests.
Lymepeople.com recommends that you do your own research to become educated about the testing options and discuss them with your doctor to determine what is best for you.