Determining false negatives

[Puzzled12]

I had a brief encounter with a girl that I received kissing and oral from. 4 days later a sore was on the inside of my lip, with two white marks but no pain or blistering. I got checked out and a nurse seemed certain it was a cold sore and told me to expect genital symptoms imminently too. She only very quickly looked at it and didn’t swab it which I now wish I had insisted on. She took bloods at the time and I was negative for both hsv1 & 2 (hsv1 was 0.164).

Since then I’ve not had anymore symptoms and after we spoke together on a zoom I waited 8 weeks and had a follow up blood test as you suggested. The results came back negative for both again which was a great relief (hsv1 ngg was 0.181).

However I’ve read on here that 30% of test are false negative so just wanted to know how you determine what the chances are in each situation. Im hoping as my levels are still low 8 weeks later and a lack of symptoms means chances of a false negative are slimmer but wanted to check for peace of mind. The nurse basically was so insistent from the initial visual diagnosis it’s hard to lose the fear I have HSV1. Thanks

[Terri Warren]

It can take up to 12 weeks to show positive on the IgG test for HSV 1 and 2, and the IgG test for HSV 1 misses 30% of HSV 1 infections compared to the herpes western blot.
What was inside your lip could easily have been a canker sore or it could have been HSV 1. Without a swab test, which she should have done before so casually said it was a cold sore, one cannot know for certain what is going on there.

If you want greatest certainty, you could do the western blot test for herpes antibody

Terri

[Puzzled12]

Thanks Terri – I guess what I’m trying to ascertain is why are 30% of hsv1 blood tests false negatives?

Does the IgG score have anything to do with it or is it irrelevant in terms of false negatives?

I’m hoping the fact that my test results after 8 weeks being low and considerably below the threshold of 0.9 (that I believe determines a positive!?) means that me getting up to that mark in another 4 weeks be unlikely? Or as I say, does the IgG have no relevance to do with potential false negatives?

If I did have HSV1 do you think I would have had genital symptoms by now if I had oral symptoms after 4 days?

[Terri Warren]

Thanks Terri – I guess what I’m trying to ascertain is why are 30% of hsv1 blood tests false negatives?
Oh, it’s a function of poor quality of these tests, nothing about you

Does the IgG score have anything to do with it or is it irrelevant in terms of false negatives?
It does not.

I’m hoping the fact that my test results after 8 weeks being low and considerably below the threshold of 0.9 (that I believe determines a positive!?) means that me getting up to that mark in another 4 weeks be unlikely? Or as I say, does the IgG have no relevance to do with potential false negatives?
It does not

If I did have HSV1 do you think I would have had genital symptoms by now if I had oral symptoms after 4 days?
Maybe, some people get symptoms as early as two days after infection, other take quite a bit longer.

Terri

[Puzzled12]

Thanks Terri – apologies but I’m slightly confused…

So any score on IgG results are essentially questionable as 30% of the time they are completely inaccurate and unreliable?

What you’re saying is it’s more a test failing completely and not picking up antibodies at all rather than it getting a slightly inaccurate scoring – for example someone with an IgG of 0.181 could have as much a chance of a false negative as someone with a 0.899?

I’m in the UK so not sure how feasible / affordable the Western Blot is or if it is that necessary as I’ve not had any genital symptoms in over 2 months since the encounter.

As an alternative, should I keep doing IgG tests weekly up to 12 weeks at different places here in the UK to ensure I’m getting as wider group of sources for a more reliable means test of IgG results?

Also, would you say i should avoid intercourse whilst I await the 12 weeks cut off? What are the chances of passing it on if i do have gHSV1?

Many thanks

[Terri Warren]

So any score on IgG results are essentially questionable as 30% of the time they are completely inaccurate and unreliable?
Any negative score, correct.

What you’re saying is it’s more a test failing completely and not picking up antibodies at all rather than it getting a slightly inaccurate scoring – for example someone with an IgG of 0.181 could have as much a chance of a false negative as someone with a 0.899?
Well, not exactly, but we don’t know where to draw that line, honestly. And the timing is essential. If someone has a 0.889 at 6 weeks out from a concerning encounter, I would definitely suggest retesting at 12 weeks out.

I’m in the UK so not sure how feasible / affordable the Western Blot is or if it is that necessary as I’ve not had any genital symptoms in over 2 months since the encounter.
We do have someone in the UK who does blood draws and helps to ship blots to the US but I’m not at all clear you need to do that.

As an alternative, should I keep doing IgG tests weekly up to 12 weeks at different places here in the UK to ensure I’m getting as wider group of sources for a more reliable means test of IgG results?
You could

Also, would you say i should avoid intercourse whilst I await the 12 weeks cut off? What are the chances of passing it on if i do have gHSV1?
People with new genital HSV 1 shed virus on about 12% of days during the first three months of infection. That does present some risk of transmission, yes

Terri

[Author]

Posts