Tests and diagnosis

By Mayo Clinic Staff

The variable signs and symptoms of Lyme disease are nonspecific and often are found in other conditions, so diagnosis can be difficult. What's more, the ticks that transmit Lyme disease also can in some cases spread other diseases at the same time.

If you don't have the characteristic Lyme disease rash, your doctor may ask detailed questions about your medical history, including whether you've been outdoors in the summer where Lyme disease is common, and do a physical exam. Lab tests to identify antibodies to the bacteria may be used to help confirm the diagnosis. These tests are most reliable a few weeks after an infection, after your body has time to develop antibodies. They include:

  • Enzyme-linked immunosorbent assay (ELISA) test. The test used most often to detect Lyme disease, ELISA detects antibodies to B. burgdorferi. But because it can sometimes provide false-positive results, it's not used as the sole basis for diagnosis. This test may not be positive during the early stage of Lyme disease, but the rash is distinctive enough to make the diagnosis without further testing in people who live in areas infested with ticks that transmit Lyme disease.
  • Western blot test. If the ELISA test is positive, another test — the Western blot — is usually done to confirm the diagnosis. In this two-step approach, the Western blot detects antibodies to several proteins of B. burgdorferi.
  • Polymerase chain reaction (PCR). This test helps detect bacterial DNA in fluid drawn from an infected joint. It's not as effective at detecting infection of blood or urine. It's used for people who may have chronic Lyme arthritis. It may also be used to detect persistent infection in the cerebrospinal fluid of people who have nervous system symptoms.
Oct. 03, 2012