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Herpes test positive then negative

A few years back I got screened for Herpes and I had a test come back positive with an IgM titer of 0.93 (the doctor explained that above 0.9 is considered positive and I should do another test since the value is low).

I got retested about a month later, and had the following results in this second round:
IgM 1.13: positive
IgG 2.21 (Type II): positive

A test for Lyme disease done as part of the same physical also came back as positive (titer 0.96 with <0.9 being negative). I read that the Lyme test can cross react during a Herpes infection.

The results came as a surprise, so I got retested a little over a week later. This third round came back negative for IgG (doctor received no titer value from the lab, just an indication that it was <0.9). No IgM testing was done.

I had left it at that for a few years, but decided recently to get tested again. The test was a Herpeselect typespecific antibody test with the following results:
IgG Type I at 0.25 (negative)
IgG Type II at 0.26 (negative)

Considering that both IgM and IgG were positive in the second round, I am still worried that something may be wrong. How should I interpret these results?
Best Answer
Avatar universal
Herpes IgM testing is quite inaccurate in adults and will often produce false positives. It should be interpreted carefully and if if positive only be used as a sign that further testing is required, with IgG. IgM on its own cannot be used to confirm a diagnosis of herpes.

The original IgG positive results, assuming it was Herpeselect as well, is a low positive and can be caused by stuff in your blood that reacts with the testing plate. Regardless of whether Lyme's bacteria was at play, confirmatory testing was always required, that level was not confirmation of infection.

The latest testing that reveals a negative is therefore quite credible as you never had a diagnosis in the first instance. I also assume that you have had no particular symptoms of concern.

A Westernblot would provide you with even more confidence but if it were me, I'd be comfortable I was negative for the virus.

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Avatar universal
Thanks for your response!
Helpful - 0
Avatar universal
Older tests had more false positives for various reasons, however the false positives still exist around 5% of times the test is applied I believe.

My previous thinking still stands, I reckon you're negative.
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Avatar universal
The first three times were in 2009. The latest test was in 2013.
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Avatar universal
At the 3.5 level, 95% or more people will truly have the virus. Most people with the infection test over 5.

How many years are we talking since that previous testing? There may have been some iterative improvements in the testing since that time.
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Avatar universal
Thank you, this is quite helpful! Unfortunately the records from the second test don't indicate what procedure was used.

The latest Herpeselect result sheet said that >=1.1 is a positive result. The second test was 2.21 for IgG, so that sounds it was quite a bit over that. Up to what value is the test considered a low positive (and how would that have to be confirmed)?

Thanks again!
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