[Question #5001] HSV IGG false positives and prior HSV1

26 months ago

Hello 
My question is two parts and the reason I am here is to decide
1. How long to wait for conclusive testing WITH prior HSV1 
2. How likely I am to get a false positive HSV2 based on past negative results 
Part one:

I have previously gotten tested for HSV2 3 times as part of full STD panels, when starting a new relationship, etc.

I have always gotten negative <.02

I recently read about false positives particularly between 1.1-3.5 and also read that this may be caused by having a protein in the blood of similar weight that trips the test.

This scares me as I really don’t want a false positive. So my questions

1. If I have gotten <.02 negatives more than once, does this mean I don’t have the false positive protein and will never get a false positive ?

2. If I was someone who is prone to false positives, would I have seen that on previous testing ? Or is each time a separate 3% (based on 97% specificity) chance of false positive based solely on imperfect testing ?

If it’s an equal chance of a FP each time...I’m not sure I want to test at the start of each relationship...that’s why I’m asking 

To summarize:

Does having multiple previous negative IGG over the years lessen my chance of a future false positive ?

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Part two:

All questions below pertain to ELISA IGG

1. If you have prior HSV1, how long is HSV2 seroconversion delayed with ELISA IGG? I’ve read everything from “not at all” to “up to a month”

2. How accurate is ELISA IGG HSV2 At 12 weeks WITH PRIOR HSV1?

3. How accurate is ELISA IGG HSV2 At 16 weeks WITH PRIOR HSV1?

4. How likely is it that prior HSV1 delays HSV2 seroconversion past 16 weeks?

5. Why are there so many discrepancies and conflicting information regarding prior HSV1 and seroconversion ?

6. Is there really any realistic difference between 14,15,16 weeks (with prior HSV1)? I hate waiting


Thank you so much!

If this is too long, please don’t delete. Please Let me know and I’ll pay for a second question 

26 months ago
I feel as if the first part of my post may be confusing in its purpose, so to further clarify:

In part one I am asking:

If I have had all negatives on previous hsv2  IGG, am I BIOLOGICALLY less likely to get a false positive for hsv2 in the future?

This will determine if I decide to screen regularly for new relationships etc

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The second part of my question is because I need to test after a recent exposure and want to know if 12 weeks is sufficient with prior HSV1 

Also:

To Terri, if you are chosen as the expert answerer, yes, I also recently posted on westover heights forum...I posted here as well because

1. I’m anxious and more answers help

2. I’m still confused on the correlation ,if any, between my prior negatives and the possibility of future false positives 

Thank you

Terri Warren, RN, Nurse Practitioner
Terri Warren, RN, Nurse Practitioner
26 months ago

1. If I have gotten <.02 negatives more than once, does this mean I don’t have the false positive protein and will never get a false positive ?

It doesn't mean you will never get a false positive, but you are less likely  to get a false positive if you have previously tested completely negative.

2. If I was someone who is prone to false positives, would I have seen that on previous testing ? Or is each time a separate 3% (based on 97% specificity) chance of false positive based solely on imperfect testing ?

Yes, you are less likely to get a false positive

If it’s an equal chance of a FP each time...I’m not sure I want to test at the start of each relationship...that’s why I’m asking 

To summarize:

Does having multiple previous negative IGG over the years lessen my chance of a future false positive ?


Yes

—————————-

Part two:

All questions below pertain to ELISA IGG

1. If you have prior HSV1, how long is HSV2 seroconversion delayed with ELISA IGG? I’ve read everything from “not at all” to “up to a month”

I would say perhaps a couple of weeks.  That's why I suggest that people wait 12 weeks to be tested, to eliminate this factor

2. How accurate is ELISA IGG HSV2 At 12 weeks WITH PRIOR HSV1?

As accurate as it is going to get

3. How accurate is ELISA IGG HSV2 At 16 weeks WITH PRIOR HSV1?

Same

4. How likely is it that prior HSV1 delays HSV2 seroconversion past 16 weeks?

not likely at all

5. Why are there so many discrepancies and conflicting information regarding prior HSV1 and seroconversion ?

i would say because it has not been studied extensively

6. Is there really any realistic difference between 14,15,16 weeks (with prior HSV1)? I hate waiting

No.


Although I understand that no one wants to get a false positive, they are pretty easy to clear up with the western blot.  Worst case there is an indeterminate, which can also be cleared up if retesting at 3 months is also indeterminate - that is considered negative.  In seven years of keeping statistics in our clinic (and we included HSV antibody testing in every STD screen unless someone specifically requested that it not be done), about 6% of tests resulted in a low positive (1.1 to 3.5).  Western blots revealed that about 50% of those were false positives. 


Terri

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26 months ago
Thank you so much
This pretty much resolves everything
I’ll wait few more days and get a final test at 12 weeks 

I just have a few final questions please:
1. Why is the recommendation of 16 weeks for hsv iGG thrown around the Internet?

2. Is there some other scenario that 16 applies to and 12 isn’t enough? Or are you under the belief that 12 weeks is always enough?

3. Based on the above answers and my lack of symptoms, I will go get tested at 12 weeks if that is conclusive with my prior HSV1

Thank you so much you have no idea the impact it has on  my life to have this advice 

L
Terri Warren, RN, Nurse Practitioner
Terri Warren, RN, Nurse Practitioner
26 months ago
1.  I'm not sure.  In years past, there was a recommendation that one wait 16 weeks for the western blot but that has been changed to 12 weeks - maybe it's a hold over from that?
2.  I believe that 12 weeks is as good as that test is going to get (which as you know is not perfect)
3.  Good.  I think that's a good move.  If you decide you want to do the blot, I can help you with that.

You are most welcome.

Terri
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