LDA/Columbia 2011
Scientific Conference

Hyatt Penns Landing

Philadelphia, PA

October 1-2, 2011

Category:  Lyme testing (blood, spinal fluid...)

If a second Western Blot is still positive for IgG and IgM, months after treatment, does that mean the Lyme Disease is still active and further treatment is neccesary?

The positive IgM or IgG Western blot indicates that your immune system is generating antibodies against some of the surface proteins that are carried by the organism that causes Lyme Disease. Your immune system however may continue to generate these antibodies long after the infection has left your body. It is not clear at this point how long the "immunologic memory" of prior infection stays active. There are very healthy people who live in Lyme endemic areas who have fully positive Western blot test results but who do not have sickness with Lyme Disease. There are also very sick people with active Lyme Disease whose Western blot test results are not positive. This may sound confusing. The problem is that the Western blot does not tell you about the presence of the spirochete itself - all it tells you is indirect information about the immune system's response to the spirochete (either present or past). Some doctors believe that the IgM Western blot, if positive, is indicative of current infection. Others believe that the IgM later in the course of illness is sometimes falsely positive and is not a good marker of active current infection. The best marker of current active infection is culture -- but culture is rarely achievable in later phases of Lyme disease. The second best marker is presence of the DNA of the organism detectable by PCR -- but this is also not often found. Unfortunately, we do not have definitive fully reliable and sensitive laboratory markers of when the infection is no longer present and when treatment should be stopped.

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