There are two types of tests that are typically used to test for Lyme disease: the ELISA and the Western Blot. They are considered indirect tests in that they look for antibodies which are generated by the body’s immune system when a person has Lyme (B. burgdorferi) disease.
Patients with persistent Lyme Disease and other TBDs seldom have a positive ELISA test, possibly because they have ceased to produce the antibodies detectable by the test. The TBDA says that the ELISA test is only about 30-60% accurate. One problem, according to TBDA is that the ELISA test is not based on the specific Lyme bacteria strain that is most useful for accurate diagnosis. While a positive ELISA test is a reasonably reliable indication of infection, a negative test is useless.
Although it still misses a percentage of people with active Lyme, the Western blot test for Lyme Disease (LD) often shows infection when an ELISA test does not. According to the TBDA, the U.S. Centers for Disease Control (CDC) have set strict criteria for considering a Western blot test as positive for LD. These criteria were established for statistical analysis of the spread of the disease and were not intended to guide doctors in their diagnosis and treatment. The CDC surveillance criteria miss many people with LD. Doctors who use only the CDC guidelines to decide whether or not to treat leave many infected people without treatment. Even if the test results are not positive by CDC standards, any positive Lyme-specific “bands” are useful indicators of infection. Another test, PCR analysis, looks for the DNA of the Lyme bacteria in blood, urine, or tissue. Multiple tests are usually required before a sample is obtained that contains the bacteria. However, in recent years PCR testing has become extremely reliable when positive. Most doctors are unaware of this test.