Non-genital outbreaks, genital shedding revisited

[JohnnyRockets]

Hello Doctors,

I was infected with HSV2 on my lower abdomen a few years ago.  My initial and recurrent outbreaks have all been around the same area below the belly button.  I used a condom during the initial infection encounter, and have not had any genital symptoms.  My doctor told me that I don't have genital shedding, but discussions here and elsewhere indicate a lack of consensus on what happens when the initial infection occurs on non-genital skin.

Given this ambiguity, I decided to try to test for shedding in myself.  I contacted Terri Warren at Westover Heights, and she suggested that I do 2 months worth of daily anogenital pcr swabbing.  I recently completed those tests (56 swabs in all), and all came back negative, including several that were taken during an abdominal outbreak.

My questions:

1)  How long would this procedure need to be done to get reasonably conclusive results?  I understand that I can't get a totally conclusive negative, but I would like an answer to the following:  What percentage of men with anogenital hsv2 will get back at least one positive swab after 2 months of daily pcr swabbing using modern pcr tests?  Or alternatively, after how many days would 99% of men get back at least one positive?

2)  Is there any merit in doing another 2 months of swabs?  Another option might be to do another round of swabbing during my next outbreak (since that would seem to be the time I am most likely to detect shedding, if ever).  

3)  Assuming I don't have genital shedding, what is the risk that I would transmit the virus from the area of infection (my abdomen)?  I have read that shedding is unlikely from this type of skin, but it would not be difficult for me to keep this area covered if there is some risk.

[Edward W Hook, MD]

You are reading it correctly.  Your situation, which is not covered by this paper, is more like the higher figure than the lower since you DO get symptomatic abdominal recurrences  

The figures, remain in your favor.  EWH

[JohnnyRockets]

Thanks for your help, Doctor.  I just have one quick follow-up regarding the numbers, if I may.

I recently came across a study published in April of this year entitled "Persons with herpes simplex virus type 2, but without symptoms, still shed virus."  

From their paper:

Dr. Wald and colleagues compared the rates and patterns of genital HSV shedding in 498 immunocompetent HSV-2-seropositive persons between March 1992 and April 2008. Each participant obtained daily self-collected swabs of genital secretions for at least 30 days. The rate of viral shedding (the presence of virus that is actively replicating, and can thereby be transmitted to another person) was measured by polymerase chain reaction (testing method for viral DNA) from the swabs.

Among the findings of the researchers, HSV-2 was detected on 4,753 of 23,683 days (20.1 percent) in 410 persons with symptomatic genital HSV-2 infection compared with 519 of 5,070 days (10.2 percent) in 88 persons with asymptomatic infection. Genital HSV was detected at least once in 342 of 410 persons (83.4 percent) with symptomatic HSV-2 infection and in 60 of 88 (68.2 percent) persons with asymptomatic HSV-2 infection during the 2 month study.

This last line is what concerns me.  From this, it looks like only somewhere between 68% and 83% of people would detect shedding within 2 months.  I thought this percentage would be significantly higher, and this gives me less confidence in my results.  Am I reading this study right?

[Edward W Hook, MD]

Welcome to our Forum. Your asking very good questions which, unfortunately, will have to be answered with statistical generalizations.  These will, I hope, be helpful, in putting your risks and questions into perspective but, as with all statistical estimates, if the odds are 1 in a million and you are "the one" little else matters.  Further, for some of your questions, the data are not all that precise due ot either the lack of studies or the limited amount of relevant study data available.  With these caveats, on to your questions.

1.  When tested by PCR performed at the University of Washington, persons with HSV-2 ano-genital infections have asymptomatic viral shedding more than 10% of the time.  A small proportion (sorry, not sure of the precise proportion and I am not in my office but certainly less than 10% of all persons with genital HSV-2) do not have shedding or at least not enough to detect in research studies.  All of the data we have however are for persons with ano-genital shedding and when you have infection at other sites such as the lower abdomen, one can be less sure that such estimates hold.  The skin of the lower abdomen is different from the skin of the ano-genital region.   Your results are strong evidence that your rates of anogenital shedding are close to, if not zero. Both your test results and the anatomy of your infection suggest this.

2.  After 56 days of testing you have a certain but not quite 100% confidence that you are not shedding.  More testing will make you a bit more confident but not much. In general the more you test, the smaller the increment in confidence in a result. This is because your greatest increases in confidence occur with early testing.  Personally I think there is little value in further testing.

3.  I think it is quite reasonable to assume that if you have HSV recurrences on your abdomen, you also have asymptomatic shedding in the same general area.  Transmission from such areas is unlikely to occur, in part because there is less direct friction to this area than to the genitals during sex.  Thus my OPINION (there are no data to answer this question, just informed and hopefully logical opinions) is that transmission is certainly a possibility although far lower than if your infection and recurrences occurred genitally.  If it is easy to cover the area, that would be the safest approach.

Thanks for your interesting question.  I hope my comments are helpful to you. EWH