Gold-standard laboratory tests are not yet available. Current tests can miss a substantial % of active Lyme disease. The 2-tier serology blood test (Elisa and a follow-up Western Blot) is an indirect test, which measures the immune response to Lyme bacteria. This test has been found to miss as much as 75% of confirmed cases of early Lyme disease [Aucott, J.; Morrison, C.; Munoz, B.; Rowe, P.C.; Schwarzwalder, A.; West, S.K. Diagnostic challenges of early Lyme disease: Lessons from a community case series. BMC Infect. Dis. 2009, 9, 79].
Direct tests are also available, including PCR and culture, which measure the actual presence of the bacteria. However, they also have low sensitivity – when they are positive, they are definite, when they’re negative, it is still not clear there is no lyme disease.
There is no one test available today that can definitely rule out Lyme disease. The best way to improve the usefulness of tests is to run multiple tests. Studies show when you combine the 2 step serology (Elisa/Western Blot) with PCR and culture, you improve your chances of accurately diagnosing your disease by 45%. However, this is still not foolproof – it still leaves a 10-20% chance of false negatives.
Patients are often told that the only reliable tests are FDA approved. That is not the case – US laboratories are licensed and monitored by CLIA (Clinical Laboratory Improvement Amendments) who ensure they meet quality standards and that the tests are reliable. So a useful test must be conducted by either a CLIA certified lab, or FDA approved. FDA reviews and approval are only required if the tests are being sold for use by other health care organizations, or laboratories. The large percent of available tests today for medical purposes are not FDA approved. Specifically: IGENEX is a specialty lab that focuses exclusively on tick-borne pathogens. They are certified by CLIA at the highest level, a specialty lab. Their tests do not require FDA approval as they are used exclusively through their lab.