What should I make of IgM positive result?

[Needsomehelp77]

Hi Dr-

I am pretty sure I am clear of HSV 1, and HSV 2, but I keep getting this positive IgM test result.  I have recently had two of these HSV 1,2, igg/igm non type-specific tests done.  Both of these tests have showed up negative igg, and positive igm with igm levels of about 2.  I had a culture done that came back negative for both types, and a type specific test that came back negative for both types.  I know you say the igm test is not an accurate test for HSV.  Believe me when I say, I am happy to hear that, but why does it keep coming back positive?  Can I have these IgM antibodies from something else?

Here is a rundown of my situation:   I have had sex with two  girls in the last six months.  The last time I had sex before my last herpes blood test was about five weeks (this girl has only ever had protected sex with me and one other guy who she dated for a while...never unprotected).  Before then, it's been about 11 weeks since I had sex with the other girl.  Both of these girls have recently had the type specific tests done, along with the igg, igm combined test.  Everything has come back negative for them.  Believe me, I have been all over this.  

I started getting these red bumps in my genital area again, along with some sort of groin rash, that has taken forever to go away.  I also got a few spots on my penis shaft that looked like some of the herpes pictures that had fluid in them.  No pain at all though, no redness.  If I couldn't see them, I wouldn't know.  So I went to the dermatologists and had them cultured within 48 hours of their appearence.  I also had an igg, igm combined antibody test.  The culture came back negative for type 1 and 2, and the blood test came back negative for igg, and positive for igm.

I recently went again, a couple of weeks later.  I had a type specific test done called Herpes 1 & 2 by EIA.  I also had another one of these HSV 1,2, igg/igm not type-specific tests done.  The Herpes 1 & 2 by EIA, which is type specific, came back negative for both types.  The HSV 1,2, igg/igm not type-specific, came back negative for igg, and positive for igm??

The two girls are negative for everything???  What do I make of this igm result.  I know my culture was good too.  I have now been tested for every STD under the sun.  Only this igm comes back positive.  

I should mention, I had a type specific test, and a culture done about a year ago that both came back negative.  The two times I have had these spots in my groin area, I have all kinds of other symptoms that happen in my body for a long time (months after).  I had the same symptoms I have been having about a year ago, and they have never really gone away.  Also, the physical symptoms I feel in my body, I have been told could be Chronic Fatigue, or anxiety/stress related.  Can these things cause skin irriations in my groin area?  Maybe that isn't your department.  I think I have given enough information.  

Thank you for all of your help!

[H. Hunter Handsfield, M.D.]

As long a enough time has gone by, the type-specific IgG antibody tests tell the truth.  Although IgM sometimes indicates HSV infection, when IgG is negative that is always the accurate result.  Since your last sexual exposure was only 5 weeks before your last test, to be certain you don't have HSV-1 or HSV-2, you might want to have a final test in 2 months, i.e. 3 months after that event.  However, if you had acquired herpes at that time, you probably would have noticed symptoms of herpes.  (None of the symptoms you describe is due to HSV.)

The reasons for false positive IgM tests for HSV antibody are varied and not well understood, and it generally is not possible to learn the reason in any particular person.  Mostly it simply has to do with the mechanics of the test; it is not usually due to some other infection cross-reacting with HSV.  (Some labs say that it's a cross reaction with varicella zoster virus, the cause of chickenpox and shingles--but the research experts disagree that is a common explanation.)  To my knowledge neither chronic fatigue syndrome or any viral infection has been shown to cause it.

So for now you can be virtually 100% certain you don't have HSV.  To take away the "virtually", have another IgG test 3 months after your last sexual exposure.  Insist that your provider tell the lab to not test for IgM antibody.

Good luck--  HHH, MD

[Needsomehelp77]

Hi Dr.-

One quick question.  The girl I had sex with five weeks ago was just tested and came back negative on her type-specific blood test for HSV 1 and 2.  She hasn't had sexual contact with anyone besides me for about 16 weeks.  If she has no long-term antibodies (igg)for herpes, and I have no long-term antibodies, it is really seeming like the igm has to be incorrect as far as HSV 1 and 2 are concerned.

Thanks again for all of your help!

PS. You must love reading these story problems all of the time!  I hope you are well compensated for all of this.  You are appreciated.

[H. Hunter Handsfield, M.D.]

I agree.  It also suggests you don't need further testing.

HHH, MD