How is Lyme disease diagnosed?

In early Lyme disease, doctors can sometimes make a diagnosis simply by finding the classic red rash (described above), particularly in people who have recently been in regions in which Lyme disease is common. The doctor might review the patient's history and examine the patient in order to exclude diseases with similar findings in the joints, heart, and nervous system. Blood testing for antibodies to Lyme bacteria is generally not necessary or helpful in early stage disease, but it can help in diagnosis in later stages.
(Antibodies are produced by the body to attack the bacteria and can be evidence of exposure to the bacteria. These antibodies can be detected using a laboratory method called an enzyme-linked immunosorbent assay.) Antibodies, however, can be false indicators of disease, since they can persist for years after the disease is cured. Moreover, false-positive tests in patients with nonspecific findings (those that are not specifically suggestive of Lyme disease) can lead to confusion. Currently, the confirmatory test that is most reliable is the Western Blot assay antibody test. More accurate tests are being developed.


Generally, Lyme blood testing is helpful in a patient who has symptoms compatible with Lyme disease, who has a history of a tick bite at least a month prior, or who has unexplained disorders of the heart, joints, or nervous system that are characteristic of Lyme disease.