[Question #3641] False positive
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87 months ago
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Exposure 1 thought to be riskier based on partner(1 encounter, oral, 2 second Genital contact, tested negative for STDs days after-no hsv test, no symptoms for months)
Exposure 2 thought to be less risky based on partner(multiple encounters after exposure 1)
19 weeks after exposure 1 and 5 weeks after exposure 2: positive IGM and negative Igg, negative swab(tested due to rash after last encounter with exposure 2) irritation/burn feeling/tingling/slight abrasions
21 weeks after exposure 1 and 7 weeks after exposure 2: positive hsv 2 igg-1.45
23 weeks after exposure 1 and 9 weeks after exposure 2: positive IGm 1.31 and negative igg hsv2: .79, yeast meds cleared rash, only dry skin now
All tests thought to be Elisa
I thought igg was always present after detected?
Does IGm matter?
Is retesting required?
Is this a false positive?
Degree of certainty?
Due to their expertise, I was hoping for Dr. Handsfield, Dr. Hook or Terri Warren to reply
I have seen prior posts similar and I am hoping to have confirmation as a post from Dr. Handsfield on dec 9, 09 seemed certain a similar situation was surely false positive
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Terri Warren, RN, Nurse Practitioner
87 months ago
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The IgG test is imperfect - there are false positives in the low positive range - going from positive to negative suggests that your positive was a false positive.
IgM does NOT matter, no
Well, that's a tough one. Your testing was done far enough out from the encounter to be as accurate as the IgG can be. If you want to be extra certain, given the ups and downs of the testing, you could do the western blot for greater certainty. I would GUESS, based on your index values, that there is about a 90-95% chance or even a little greater, that you are actually negative. I would not say anything for certain here but the likelihood is that since you ventured back into the negative range that this is a false positive.
Were you contacts condom protected?
Terri Warren
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IgM does NOT matter, no
Well, that's a tough one. Your testing was done far enough out from the encounter to be as accurate as the IgG can be. If you want to be extra certain, given the ups and downs of the testing, you could do the western blot for greater certainty. I would GUESS, based on your index values, that there is about a 90-95% chance or even a little greater, that you are actually negative. I would not say anything for certain here but the likelihood is that since you ventured back into the negative range that this is a false positive.
Were you contacts condom protected?
Terri Warren
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87 months ago
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Hi, thanks for your response.
Neither exposure was condom protected but more familiar and confident about partner in exposure 2, however based on my research it seems very unlikely that the contact in exposure 1 would cause hsv2(very short non penetrating genital contact-2 seconds max, and 5-7 min oral contact) - is that assumption on likelihood correct?
The contact coupled with the time since and my test results make it seem very unlikely that exposure 1 would have caused the positive result. Of note, a couple of months prior to my first test I tested positive for CMV.
The fact that I tested positive for IGm or igg is unfortunate and the continued positive IGM makes me worry-even though i know from the research it shouldn’t. I plan to do the western blot, I believe i need to wait 16 weeks since last exposure, is that correct? If negative, would that be conclusive?
I’ve copied the link where Dr. Handsfield says he is certain a similar situation was false positive-in my case the testing seems to be a little further out from exposure than the person Dr. Handsfield is addressing. Is there any updated science since then that would lead you not to say you are certain or is this just a difference of professional opinion?
I certainly feel an obligation towards future partners in the event that this was a true positive, any suggestions on dealing with that?
I know there are other tests because the experts on this forum always ask, but what are some examples of other IgG Antibody tests that are not “Elisa”?-I believe mine were Elisa but I am curious.
Below is the link and a copied response from Dr. Handsfield for a similar situation:
Welcome to the STD forum. The bottom line is that you are not infected with HSV-2. Your initial weakly positive result was false. Have I ever heard of this sort of situation? Yes, all the time.
False positive HSV-2 tests are quite common, especially when the result is only weakly positive. Although ELISA values over 1.1 are technically positive, in fact the result is not definitive unless 3.5 or higher. When two results are like yours -- one weak, the other definitely negative -- it is always the negative result that is valid.
False positive HSV-2 tests are quite common, especially when the result is only weakly positive. Although ELISA values over 1.1 are technically positive, in fact the result is not definitive unless 3.5 or higher. When two results are like yours -- one weak, the other definitely negative -- it is always the negative result that is valid.
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Terri Warren, RN, Nurse Practitioner
87 months ago
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The antibody tests for herpes can use different names but they all (except for western blot) look for a protein associated with the antibody that is distinct between HSV 1 and HSV 2. That is why they are called type specific.
In your case, since you went from a low positive to a negative, I think it is certainly most likely that you are negative. It is normal, however, that you feel a bit less certain given the once positive 1.45 index value. The IgM test should be ignored (I know that's difficult too - it should never have been done in the first place). You can do the western blot at 12 weeks out, should you decide to do that. The University of Washington has changed their recommendation from 16 to 12 weeks in the past couple of years. The odds are very high that you are negative - can I say for sure that you are? No. We know the IgG test misses 8% of HSV 2 infections compared to the western blot so to say I'm certain would not make sense but is it likely that you are negative? Yes, very likely.
Terri
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In your case, since you went from a low positive to a negative, I think it is certainly most likely that you are negative. It is normal, however, that you feel a bit less certain given the once positive 1.45 index value. The IgM test should be ignored (I know that's difficult too - it should never have been done in the first place). You can do the western blot at 12 weeks out, should you decide to do that. The University of Washington has changed their recommendation from 16 to 12 weeks in the past couple of years. The odds are very high that you are negative - can I say for sure that you are? No. We know the IgG test misses 8% of HSV 2 infections compared to the western blot so to say I'm certain would not make sense but is it likely that you are negative? Yes, very likely.
Terri
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