This article is from the Lyme Disease
FAQ, by Milo7
As explained in Forschner-Vanderhoof, K., Everything You Need to Know About
Lyme Disease, p.67: It is possible to have Lyme disease even if your
laboratory tests are negative. This is because a negative test can simply
mean that the laboratory did not find any measurable Lyme disease
antibodies in your sample(s). Other reasons include:
1) Your blood sample was taken too soon after infection for your
immune system to have mounted a detectable response. An antibody
response is rarely measurable when the EM rash first appears.
2) You are producing detectable levels of antibody, but the laboratory
made a mistake.
3) You are producing antibodies to a strain of Borrelia burgdorferi
(Bb) that the laboratory cannot detect.
4) You are producing antibodies, but they are bound to the Lyme
disease bacterium (creating what is called a complexed antibody)
without enough that are free-floating and readily detectable.
5) Your immune system may be compromised and is not responding
properly to the bacterial invasion.
6) By taking antibiotics early in the disease (or for another recent
or concurrent illness), you have aborted your immune system response.
(This is not necessarily bad because the immune response does not
always eradicate Bb anyway.)
7) The bacterium has changed its make-up, and your immune system has
not noticed it.
8) The bacterium is cloaking itself within an immune system cell,
limiting your body's capacity to identify and combat it.