I have positive IgG HSV-2 on a blood test but negative on the western blot test. Kindly help.

Q. Is it a concern when IgG HSV-2 is positive on a blood test and negative on the western blot assay?

Answered by
Dr. N. Ashok Viswanath
and medically reviewed by iCliniq medical review team.
This is a premium question & answer published on Jun 16, 2022 and last reviewed on: Jul 13, 2023

Hi doctor,

Six months before, I ordered an STD panel and received a high level of herpes-2 on the IgG test. I did a retest using IgG four days later and got a high result. Then about six weeks later, I sent in a sample for western blot, and it came back negative for types 1 and 2. My partner did the same and was positive for both 1 and 2. We have since stopped having sex. Do I need to be further concerned or do another test?



Welcome to icliniq.com.

I can understand your concern. Your herpes-2-IgG is positive, and your western blot test is negative in the report (attachments removed to protect the patient's identity). Since your western blot (gold standard serological test) came negative, we can take it as conclusive evidence. The positive IgM test could be attributed to false-positive results due to prior infection with chickenpox (varicella zoster) or other self-limiting infections like cytomegalo viral infection. It can happen due to cross interaction of closely related antibodies with specific enzyme-based test methods, resulting in the false-positive test results. Since western blot is a highly specific and sensitive test, we can take it as conclusive evidence. Since your partner's result came back as positive, the test can be considered positive. I suggest your partner can go for tests like the HSV DNA PCR test to rule out if there is an active infection for your partner. Since the western blot is negative for you, there is no need for other tests or investigations. Therefore, there is no need for any concern.

Stay calm and relaxed. Take care and have a great day.

Hi doctor,

Thank you for the reply.

Since my partner and I are in a casual relationship, I do not have the intention of spending the rest of my life with her. She does not want to pass anything on to me. So we decided to stop seeing each other. I appreciate you saying no concern for me; however, I want to be clear. We were having unprotected sex up to a few days after the western blot sample was taken. We stopped having sex a few days after I sent the samples for western blot. Is there a window period? Will the test will show if I contracted it? Sorry, it is just a bit confusing since, for about a month or so, we both thought we had it, and neither of us has had any symptoms or sores whatsoever. So from that, I assume my risk factor is very low since apparently, I had not contracted it since nine months when we first started having sex. Here is the timeline. We had first-time sex using condoms nine months ago and continued for four months. When we both tested positive, we did sex without condoms (since we both thought we had it anyway). Then I had no sex for about three weeks due to being out of town. Then unprotected sex again several times over two days before four months, when western blot was taken, and results were delivered. After that, no sex. I have had no sores, sickness, or anything, and neither has she. I know you said before that there is no need for further tests on me but knowing this timeline, what are your thoughts?



Welcome back to icliniq.com.

I can understand your concern. The incubation period for herpes simplex ranges from 2 to 12 days with an average of six days, after which you would have at least a milder form of the disease like rash, vesicles, or blisters in your mouth or genital areas. In rare cases, you could be asymptomatic. Since you gave the history of unprotected sexual exposure after providing a blood sample for the western blot test, there are some chances of infection spread (the chances are low, without any active lesion). The serological window period for HSV is approximately the 4th week to the 6th week following exposure, after which the antibodies are found in the serum in detectable amounts. You can get tested again by a western blot test method. This test is to rule out any asymptomatic infection.

Do not worry. Mostly the test would be negative. So stay calm and take care.

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