Types of Lyme Disease Tests
There are a number of different types of Lyme disease tests, all with varying degrees of accuracy, and applications in a variety of patient scenarios. Western blot, enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) can all be carried out through a blood test after venipuncture, or by testing the cerebrospinal fluid following a lumbar puncture (spinal tap). Lumbar puncture gives a more reliable diagnosis but is more difficult to perform and the antigens are often elusive in cerebrospinal fluid leading to a positive finding in only 10-30% of those patients cultured.
PCR Tests for Lyme Disease
Standard Lyme disease testing involves either an ELISA or an IFA followed, if positive or indeterminate, by a Western blot test. More expensive and time-consuming tests such as PCR tests require experienced laboratory technicians and are still susceptible to false positives particularly from blood and cerebrospinal fluid samples. PCR is more reliable for detecting OspA DNA in synovial fluid however, making it useful in diagnosing Lyme arthritis. PCR is the only practical means of directly detecting the presence of the infectious Borrelia bacteria, with other tests, such as those mentioned above, merely testing for antibodies to the organism. As such, a positive result may indicate either current or previous infection and is not necessarily proof of active infection causing Lyme disease.
PCR tests, along with serological tests rely on detecting the genetic material (DNA) of the suspected infectious spirochaete or the antibodies to such bacteria. Where a patient has stored a removed tick for analysis it can be helpful to perform PCR testing on the tick to detect the presence of Borrelia bacteria and other possible infectious organisms. In light of the rapid hybridization of Borrelia bacteria, and the possibility of antibody cross-over in the presence of co-infection with Epstein-Barr, cytomegalovirus, or herpes simplex, results can easily be erroneous. High titers of immunoglobulin G (IgG) or IgM antibodies to Borrelia antigens indicates the presence of disease, but low titers may mean either an early stage of infection or residual antibodies from a previous infection. IgG antibodies can remain in the system for many years, and even IgM antibodies, which are the first responders to infection, can remain long after the initial infection.
Unproven Lyme Tests
Types of tests for Lyme disease which remain unproven include antigen Lyme tests and PCR tests on urine, immunofluorescent staining for those forms of Borrelia bacteria that are cell-wall-deficient, and a new LTT-MELISA test. Lymphocyte transformation tests are also unproven and the increasing use of potentially inaccurate testing is worrying when considering the possible ramifications of misdiagnosis with Lyme disease, inappropriate long-term antibiotic treatment, or even a missed diagnosis of Lyme disease leading to persistent symptoms which could have been treated at a much earlier stage if the appropriate types of Lyme disease tests had been carried out.