Negative Western Blot after 2 very high positive HSV-2 IgG tests

[trey24]

Hey Terri

I’m a 19 y/o male and on March 26th I had an IgG test for HSV-2 that returned positive with an IgG of 6.50 from LabCorp. I was taken completely by surprise since I’ve never had any symptoms before and it would’ve meant I’d contracted it when I was 16 at the oldest. I got another test on April 14th at a different lab just to confirm and it was positive with IgG of 7.08 this time. I ended up getting a WB a couple weeks ago just for peace of mind and I actually tested negative for both HSV 1 and 2

I realize this is highly uncommon and I wanted to ask what you make of the situation. Do you think I should take this WB result as the final confirmative result? If the WB can be taken as 100% confirmative then I’d also like to figure out what could’ve possibly been tripping the IgG test that hard and if that’s an issue worth looking into. I have a couple things I suspect could be tripping the test that I’ll go more into detail about if you think it’s worth discussing.

Your forum has helped me a lot in the past several weeks and I’ve learned so much. I wouldn’t have considered the WB after my 2 high positive tests if it weren’t for some of your responses to other questions I saw on here. I appreciate you!!

[Terri Warren]

It is NOT uncommon! I order about 15 western blots a week and I’ve seen false positives at 17 with several in the 12’s and 13’s.
Immediately when I started to read your post I suspected a false positive because people entering UW (Age 18) only 3% are positive for HSV 2.
I’m so glad you did the blot, congratulation on your good sense!

Terri

[trey24]

Thank you!

Since my first post I’ve talked to my doctor about the WB result and she didn’t know what to make of it so she consulted an infectious disease specialist and I’ll paste what the specialist said down below.

“I asked ARUP labs regarding the sensitivity and specificity of the test and they report:
0050294 / Herpes Simplex Virus Type 2 Glycoprotein G-Specific Antibody, IgG by CIA, the analytical sensitivity is Sexually active 98.1%, Expectant Mothers 94.8%, Low Prevalence 100%
Specificity: Sexually active 98%, Expectant Mothers 97.3%, Low Prevalence 100% – ARUP Laboratories, accessed 6/21/23

Thus as you can see, this is a very specific test (ie there are extremely few false positive). Thus we do not recommend follow up with Western blot testing.
The Western blot confirmation suggestion per the CDC STD guidelines is to follow up less specific testing, for example by EIA testing which can have reported specificity of only 57.4% (ie many more false positives).

The Western blot test performed on this patient is not FDA approved. I do not have information regarding the sensitivity and specificity of this test. If desired, one could contact the lab performing the test to determine the sensitivity / specificity. Infectious Diseases will not be doing this.

Overall, given the very high specificity of the HSV2 IgG test, I would interpret this as consistent with HSV2 infection. Particularly given per note 4/14/23 patient also tested positive at a different outside lab previously. As well as the antibody level is semi-quantitative and clearly above the positive threshold at 7.08. In this overall context I would interpret the UW Western blot negative result as a false negative.”

What’s your response to that? My understanding is the WB has the final say and that there’s also literal misinformation within what the specialist said. I want to assure my doctor that the WB is the gold standard but it’s likely they’ll take the specialist’s word over mine.

[Terri Warren]

Sorry, this is completely incorrect. The specificity of the test is very poor and the CDC now recommends that it not be done, based on poor specificity. This ID doc is clearly not familiar with the western blot. The IgG test is under the microscope now with the FDA, NIH and CDC. I’m so sorry this is confusing for you. I believe you can trust the blot. I’ve had false positives as high as 17!

Terri

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