Lyme disease tests are used to determine if a person with characteristic symptoms has been infected by Borrelia burgdorferi. If the doctor suspects a recent infection, then she may order both an IgM and IgG antibody blood test. If they are negative but symptoms persist, then the tests may be ordered again a few weeks later.
Acute and convalescent samples may be used to track progression of the disease by looking for changes in the amount of antibody present. If the tests are positive, then a Western blot test is ordered to confirm the findings.
Lyme disease can sometimes be challenging to diagnose. If a person has removed a tick from his skin, had a known tick bite, and lives in or has visited an area of the country where Lyme disease is most prevalent, then the timing of the potential infection can be closely estimated. However, the tick is about the size of the head of a pin and the bite may not be noticed. Not everyone will develop the characteristic rash, and the symptoms that a person does have may be nonspecific and flu-like in the early stages, with joint pain that develops into chronic arthritis and/or with neurological symptoms that appear months later.
A blood test for antibodies to the bacterium is the preferred test for the diagnosis of Lyme disease. However, if a person has central nervous system symptoms, such as meningitis, then IgM, IgG, and Western blot testing may sometimes be performed on CSF.
Occasionally, PCR (polymerase chain reaction) testing is performed on a sample because it is a more sensitive way of detecting an infection with B. burgdorferi. This method is useful in detecting the infection in samples such as fluid collected from a joint. It looks for the genetic material (DNA) of B. burgdorferi in the joint fluid (synovial fluid).
Very rarely, a sample, such as a skin biopsy, may be cultured to grow the bacterium.
Lyme disease testing is ordered when a person has symptoms suggestive of an infection with B. burgdorferi and lives in or has visited a region where deer ticks or black legged ticks are common, especially when the person has recently been bitten by a tick.
Less commonly, heart problems such as irregular heartbeat and eye inflammation
IgM and IgG tests are ordered first. Western blot testing is ordered as a follow-up test when the first tests are positive or indeterminate. Acute and convalescent samples may be ordered several weeks apart to look for changes in antibody levels.
When someone does not have typical symptoms or a history of a tick bite and has not been in a region where Lyme disease is prevalent, then the doctor may rule out other causes for the person's symptoms before suspecting and testing for Lyme disease.
A healthy adult who has never been exposed to the B. burgdorferibacterium will not have any antibodies.
If a person's IgM, IgG, and Western blot tests are positive, then it is likely that the person has Lyme disease. If the person's antibody concentrations rise over time, then it is likely that the person has an active B. burgdorferi infection.
If someone tests positive for only the IgM antibody, then the person may have a very recent infection or a false positive test result.
If an IgM result is not detectable but the IgG and Western blot tests are positive, then it is likely that the person tested either has a later stage infection or had an infection at some time in the past.
If all tests are negative, then either the person's symptoms are due to another cause or the antibody levels are too low to detect at that time; retesting a few weeks later may be needed to confirm or rule out infection.
The following table summarizes results that may be seen with Lyme disease antibody tests.
Likely Lyme disease
Early infection or false positive
Late or previous infection
(usually not performed if IgM and IgG are negative)
No infection present; symptoms may be due to another cause or antibody levels too low to detect
If PCR testing is performed and the result is positive, then it indicates a recent infection with B. burgdorferi. If the PCR test result is negative, then no infection is present or the levels of DNA are too low to detect.
This article was last reviewed on August 9, 2012. | This article was last modified on February 24, 2015.
The review date indicates when the article was last reviewed from beginning to end to ensure that it reflects the most current science. A review may not require any modifications to the article, so the two dates may not always agree.
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