Low positive IgG for HSV-1 -- possible false positive?

[wondering2014]

I just got, for the first time, a positive test result for HSV 1. IgG value 1.42. HSV 2 tested negative.

I had a possible oral and genital exposure from an encounter about 16 weeks before the test. I was also tested about two weeks after that encounter and at that time I got negative results for both HSV 1 and 2.

So if I do have HSV 1, it could have come from that encounter (though I understand I could have gotten it somewhere else also). I don't have info about the status of the person I might have gotten it from.

I have never had any HSV symptoms, sores or outbreaks. Since the 1.42 value seems to be in the lower range of positive, I'm wondering if there is a chance it's a false positive, and if I should get tested again in a couple of weeks.

I've heard that any IgG result below about 3.5 has a better chance of being a false positive -- is that true for both HSV 1 and 2?

thanks!

[exchangesquare61]

Hi wellinformedperson, I was recently tested with low positive of hsv 1 at igg 1.4. I have no symptom. The doctor said likely false positive and asked me to forget the whole thing and move on with my life. The doctor warns against re-test and commented what if a second low positive again OR a slightly higher positive reading - what am I going to do about it. But having tested positive, I am thinking to re-test but also afraid on the outcome of second test. Common for low positive hsv 1 below 3.5 to be false positive?

[WellinformedPerson]

I do not believe you have a recent infection due to your encounter 16 weeks before your test. That assumes you were not infected prior to that encounter and would not have had any antibodies to either strain of hsv. If that were the case, I think you would have experienced very obvious symptoms, i.e. blisters, lesions, sores.

If you truly are infected with hsv1, I would suspect you have been infected for a very long time. Like an oral infection since childhood and do not get recurrent infections. The level of the index value is no indication of how long you might have had the infection. They bounce around even in people that have been infected for a long time.

In addition, the IgG test for hsv1 misses at least 10% and maybe as much as 30% of infections in people confirmed infected by culture, which means they have an index value below 0.90 and have obvious herpes symptoms confirmed by culture.

Without obvious symptoms 16 weeks ago before your test, I highly doubt you were infected at that time. You test result could very well be a false positive. Without symptoms and confirmatory testing, it is hard to know for sure.

[WellinformedPerson]

Excuse me, in the second paragraph of my reply I meant to say, "... and do not get recurrent outbreaks."

[wondering2014]

hey Caveman1, thank you for replying and for the advice!

Yeah, we are in the same boat. I'll probably get the IgG again first (it's pretty cheap with my insurance), and if it's negative I might just leave it at that since I haven't had any symptoms. Maybe the Western Blot later on if I still feel I need peace of mind.

Let me know how your Western Blot turns out and good luck!

[Life360_Dave]

Tests tell specific its his hsv1 or 2. At this point you need to retest but if it comes back positive again we wont know where you have it. You mention recent oral sex and you might have it in the gential area but you would have to wait for a sore to be swabbed to confirm location. Retest to at least establish if your positive. If it is positve again with a slight rise, it very well could be genital unless you had some deep rubbing kissing with her as well.

[wondering2014]

Thanks for the reply. I know it's impossible to tell much from posts in a forum, but I've been reading up some and I do have a general question about the false positives for these IgG tests:

It seems pretty well-established that for HSV-2, an IgG result below 3.5 might well be a false positive, but it also seems like less attention has been paid to the parallel question of IgG false positives for HSV-1.

Are the tests and viruses similar enough that we can also assume that IgG results like mine (1.42) for HSV-1 are likely false positives, or is there some important difference there between the tests, or is there just not enough data/studies to say at this point?

I'm not all that worried about HSV-1, I'm in my early 50s and I know most people my age have it anyway, and I haven't had any outbreaks. But I would like to know exactly what my status is and whether future outbreaks might be a possibility for me.

thanks again!

[Life360_Dave]

Hi, theres a chance its a false positive but appears more of a recent infection for hsv1. retest to confirm.