[Question #5183] Herpes Concern

76 months ago

Dr. Hook,

In early February I had a sexual contact with someone in Japan whose sexual history I don’t know. All sex, except oral was protected, but there may have been some skin to skin contact in the groin area. The day after I returned to the U.S. I noticed a small rash on my inner thigh not right near my penis but about an inch away. It was a bit itchy. I went to the dermatologist the next day. They were pretty certain it was a mild case of shingles or maybe a fungal thing, but they took a culture to test for HSV at my request. They did an AG test with immunuflourescence and it came back negative. On recheck it was mostly healed, but had minor scarring of dark coloration, and they were certain it was shingles. I got the first dose of inactive shingles vaccine about three weeks ago. There is still a slight dark skin scaring where it was but it has faded a lot.

Fast forward a couple of weeks and I got follicultis in one spot at the same location (the dermatologist said it was definitely folliculitis) and I went to Japan for work again. Upon return I noticed a couple more spots in that area and its been itchy. I am pretty sure it is folliculitis, but am nervous because its in the same location as before and I read online that the HSV AG can give false negatives if done more than 48 hours after symptoms first appear. I think it was done within 48 hours, but given the travel it could have been 72 or even a litle more since I didn’t notice until a day after I returned when the itch started. I am pretty sure that they got the sample that was negative from a fresh sore/blister that was likely there less than 48 hours. Since I had the first dose of the shingles vaccine I am pretty sure what I have now isn’t shingles so I am worried maybe the HSV AG was a false negative last time. Of course, it could just be folliculitus since its near where the dermatologist saw that.

76 months ago

Oops-my question is given the above how much can I rely on the HSV AG test?

Terri Warren, RN, Nurse Practitioner

76 months ago

I think you are referring to the IgG test, yes? IF you got new infection, it can take weeks for that test to be positive or it could be positive as soon as 2-3 weeks but certainly not within 48-72 hours. So you are saying that the swab test was negative. It worries me a bit that they thought it could be shingle since herpes and shingles look very similar. I would suggest repeating the IgG test a few weeks down the road

Terri

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76 months ago

Sorry if I wasn't clear. They did not do a blood test. They did a culture from the rash which was fresh at that time, and they got a good sample from a fresh blister (most likely within 48 hours of the first symptoms). They were almost certain it was shingles or perhaps fungal even before the HSV test came back negative, but they and I wanted to be sure it was not HSV, so cultured for HSV as well (the results of the culture were negative). My concern arose when I read online that cultures can give false negatives if taken after 48 hours of noticing symptoms. This culture was almost certainly taken within 48 hours of the first symptoms, but given the travel time on the airplane it could have possibly been within 50-72 hours of me noticing the first symptoms; although the area they cultured from was newer.

76 months ago

I wrote the following in reply but forgot to mention the type of test they did on the sample is called a PCR test if that helps: Sorry if I wasn't clear. They did not do a blood test. They did a culture from the rash which was fresh at that time, and they got a good sample from a fresh blister (most likely within 48 hours of the first symptoms). They were almost certain it was shingles or perhaps fungal even before the HSV test came back negative, but they and I wanted to be sure it was not HSV, so cultured for HSV as well (the results of the culture were negative). My concern arose when I read online that cultures can give false negatives if taken after 48 hours of noticing symptoms. This culture was almost certainly taken within 48 hours of the first symptoms, but given the travel time on the airplane it could have possibly been within 50-72 hours of me noticing the first symptoms; although the area they cultured from was newer.

Terri Warren, RN, Nurse Practitioner

76 months ago

The PCR is the best type of swab test - that's great news. If that is negative, that's a very good sign that the blister was not herpes. My recommendation is still to obtain an IgG test down the road a ways

Terri

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76 months ago

Thank you!