› Forums › Herpes Questions › Negative Western Blot after 2 very high positive HSV-2 IgG tests › Reply To: Negative Western Blot after 2 very high positive HSV-2 IgG tests
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.