Lyme disease (Lyme borreliosis) is diagnosed using 2 tests conducted in sequence. A first test (Lyme disease serology) screens for all antibodies that may be associated with the presence of the bacteria responsible for the disease. Since several antibodies can produce false positive results in this first step, all positive or inconclusive serological test results must be confirmed by a more specific analysis called immunoblotting. The results of this second test are used to confirm the presence of the disease.
Negative serological test results indicate that Lyme disease is probably not involved. However, a note indicates that samples taken too early (less than 2 weeks after the onset of symptoms) could contain too few antibodies to test positive. If there is strong clinical suspicion, a second serum sample must be collected 7 to 14 days after the first.
Due to the risk of generating false positives, health organizations (Centers for Disease Control, Laboratoire de Santé publique du Québec, etc.) recommend that immunoblotting should not be done when the first-line serological test is negative.