Western blot accuracy and equivocal HSV II results

[infowoman84]

In August, I asked my new partner to get a herpes blood test as a precautionary measure. He has never had any symptoms of herpes. His last sexual encounter was early May 2013 –approx. 4 months ago.  On 9 August, he took Herpeselect 2 Elisa IgG blood test. He scored negative for HSV I but scored - H.107 for HSV II.  Report indicated 01.10.  So his result .107 indicated “equivocal”.  There were problems at the lab and his HSV II sample was sent to another for re-testing. When it came back equivocal 2 weeks later I suggested another.
On 23 August (2 weeks later) he took- HSV 2 IGG HERPESELECT AB. Scored 0.93. Lab report said determination was “equivocal”. The index: H 0.00-0.89 INDEX. So  2 equivocal results: 1.07 and 0.93.  I have now ordered the western blot test. It can’t be performed in NY anymore so we’ll have to travel to NJ.  My questions:
1. Can you explain the reasons for “equivocal” results? I was told it can indicate recent exposure or a false-positive but can there be other reasons? For eg my partner had the Epstein bar virus in his teens.
2. Would antibodies have developed by the time he took the test at 3 month mark?
3. I have read that in recent times the western blot has been giving quite a few false-negative results for people who had previously tested positive on a blood test. So I am wondering about the accuracy for my partner at the 4 month mark post-sexual encounter.  In light of these false-negatives, how long should we wait to undertake this test for accuracy
1) Would you recommend in addition to/or instead of the western blot, a repeat of Herpeselect Elisa blood test which clinic recommends for any equivocal test result? Alternatively, should we get both done ie. repeat herpeselect test, then western blot.  My concern with western blot is that it’s known to detect a positive result a little later in infection than say Elisa.

[Terri Warren, RN, Adult Nurse Practitioner]

1.  No, it can take up to 4 months to develop antibody. Most people do it much sooner, a very few do it later, particularly if they have taken antiviral medicine.
2.  Yes, a person who is uninfected can continue to get equivocal results or even positive results due to some other protein in their blood that is artificially tripping the herpes test.  We see it all the time.
3.  The test picks up 97% of those infected with HSV 2, according to the package insert.  That is how much you can trust the test.

Terri

[infowoman84]

Thanks! But just to answer my questions specifically to clarify this in my mind:
1) Are you saying 4 months is the absolute minimum time it takes anti-bodies to develop or can it take much longer or shorter than that?  What I'm getting is that how I can be sure if I get it at at 4 months that I will be safe? I know you get hypotheticals all the time and that obviously there are going to be exceptions to the rule, but generally what is the MINIMUM time a person should wait?
2) Can a person who definitely HAS NOT got herpes continue to score "equivocal" results in continuous blood tests OR will eventually with time will they drift into the negative or positive category?
3) If we do choose to get Elisa again and he scores negative, can I trust the negative result (or trust it if he scores positive) in the absence of symptoms?

Thanks Terri! I appreciate you taking the time to write to me and apologize for the additional questions.

[Terri Warren, RN, Adult Nurse Practitioner]

I am not seeing more false negatives on the western blot recently, they are kind of spread out of time.  If that's what I said, then I said it incorrectly.  They are there, but not common for sure.  What I have been seeing lately are more false positives at higher levels on the ELISAs test.

If you are going to get a western blot after the appropriate time, I don't htink you need to get another ELISA or any ELISA.  yes, four months.

Terri

[infowoman84]

Thanks Terri - in response to your question, I read that the western blot is recently giving false negative results for those who previously tested positive on a number of herpes forums on the topic. Also, I read a comment from you yourself in response to a person's query in which you said in the last 6 months you had seen more than usual false-negatives on western blot and you weren't sure why that was happening - hence why I was alarmed.

2 follow up questions:

1) Will get WB as you suggested, but is it also worthwhile to get elisa too for extra certainty?
2) Is 4 month mark the minimum or the maximum a person should wait? I really don't want to expose myself to any risk.

Thank you!

[Terri Warren, RN, Adult Nurse Practitioner]

"I have read that in recent times the western blot has been giving quite a few false-negative results for people who had previously tested positive on a blood test. So I am wondering about the accuracy for my partner at the 4 month mark post-sexual encounter.  In light of these false-negatives, how long should we wait to undertake this test for accuracy "  Really? Where did you read that?  In 31 years of practice, I have had 9 people who tested positive by swab test and negative by western blot.  That's not very many!  

It isn't possible to know why someone gets an equivocal test but they are pretty common.  My recommendation would be to wait 4 months from last possible exposure and retest with western blot.

Terri