Claudia, I share these very same questions. How do clinicians decide, based on IgG values, if an infection is active or not?
They don't, as I understand it.
What was being said, was that in a longstanding infection, there should be a robust IgG response.
I think that this really goes to the issue of "false positives" rather than whether there is active infection or not.
What is curious about what Claudia has said about her son's case, then, is the lack of IgG. If there were, indeed, persistent or relapsing infection, then you would expect to see what the material she, herself, quoted, above, indicates:
IgG titers produced in response to all examined Erp proteins also varied over time, and often increased, suggestive of continued stimulation of the immune systems throughout duration of the infection.
And there are problems with the diagnostic usefulness of late-stage IgM reactions as Henry explained, previously:
Since IgM antibodies against some of these minor determinants will bind to some of these irrelevant cross reactive determinants, the likelihood of getting a false positive test is increased if one is using a diagnostic test based on the detection of IgM antibody late during an immune response.
My understanding, also, is that IgG repsonses are negatively affected by antibiotic administration in EARLY stage ONLY...before the IgG response has had time to adequately form.
So, it wouldn't appear to be a factor, if there were an ongoing, longstanding infection.
As I understand it.
(Anyone else on this)?