A number of people have asked about the more technical aspects of the myLyme test. Several wanted information on the accuracy of the test and the methods the laboratory uses to determine results. As recommended by the Centers for Disease Control and Prevention (CDC), myLyme is actually two separate testing procedures—an enzyme immunoassay (EIA) screening test and an immunoblot (sometimes called Western blot) confirmatory test. The procedure tests for antibodies to Borrelia burgdorferi, the bacteria responsible for causing Lyme disease. The methodology used by our reference laboratory is very specific and will only detect infection with Borrelia burgdorferi sensu stricto.
IgG and IgM are the antibodies that are tested for an accurate result. IgM antibodies are made sooner, so testing for them can be helpful in identifying Lyme disease during the first few weeks of infection. IgG antibodies in sufficient quantity for testing, appear 4-6 weeks after a tick bite. IgG antibodies persist in the blood for years.
For the screening test, sensitivity (ability to correctly detect those with the disease) is >95% and specificity (ability to correctly detect those without the disease) is 96%. Since some other antibodies may interfere with the screening test, all positive results are confirmed with an immunoblot test. Laboratory accuracy is 100%.
The confirmatory test, or immunoblot, detects both the IgG and IgM antibodies. Sensitivity for the IgM antibody is >97% and specificity is 100%. Sensitivity and specificity for the IgG antibody in the immunoblot test is 99%.
These kits are very specific and will only pick up infection with Borrelia burgdorferi sensu stricto.
The table below summarizes this information.
|EIA screening test IgG/IgM||96%||95%|
|Immunoblot confirmatory test IgM||100%||97.1%|
|Immunoblot confirmatory test IgG||98.5%||98.8%|