The Test
How is it used?
When is it ordered?
What does the test result mean?
Is there anything else I should know?
How is it used?
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.
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