Lyme disease Borrelia IgG and IgM

Lyme disease, Borrelia IgG and IgM

There are two types of antibodies that are tested for: IgM and IgG. IgM is produced by the body first and then IgG. It takes several weeks before enough antibodies are produced to be detectable.

IgM usually disappears again after some months, but can also remain present in Lyme disease. It can also happen that a disappeared IgM becomes positive again after some time. IgM is, according to some experts, an indication of a persistently active infection. IgM is only produced if there was contact with the antigen (the bacteria) a short time ago, because the cells that produce IgM have no so-called 'immunological memory'.

IgG, on the other hand, can remain detectable in the body for years, even after the bacterium has disappeared from the body. A positive test for IgG can therefore fit both a longer existing active infection and a cured infection. If there is a negative result it is called seronegativity. It has been shown that seronegativity can occur in an active infection.

Test results alone cannot be used to definitively establish or exclude the diagnosis. In many cases only a combination of data can lead to the (most likely) diagnosis. A nuanced form of diagnostics in which clinical data play an important role and in which the various degrees of certainty are expressed is recommended.