[Question #8889] Genital HSV-1: Immunity from prior oral HSV-1 infection, & Valacyclovir

38 months ago

Hi experts,

Thanks in advance for any help! I am a medical student who recently started dating a girl with a history of HSV-1 genital herpes (no HSV-2), and I have concerns around transmission. She’s had it for at least a few years with no outbreaks or symptoms in at least 2 years. I have looked at official guidelines, UpToDate, and many research papers, but have been unable to find some key data. My questions relate to statements made in doctor Handsfield's video on this website. the first being the most of interest:

In his video at 04:29 Dr. Handsfield implies that if an individual has prior HSV-1 infection (let's presume it was contracted orally as most people do), that would make it very unlikely that person would become infected in their genitals with HSV-1. I was wondering if you could point me to the studies or data which indicate this, as I have been unable to track it down.
Dr. Handsfield also states that valacyclovir should drastically reduce transmission of genital herpes - I have only really found data relating to valacyclovir reducing HSV-2 transmission (by about 50%). Could you point me to the data that shows its efficacy for reducing genital HSV-1 transmission?

Thanks so very much for your time and thought regarding this, I appreciate you all!

Terri Warren, RN, Nurse Practitioner

38 months ago

I am not aware of a specific study to document the lack of acquiring HSV 1 in a new location, but those of us who specialize in this disease would all agree that we either have never seen it or very rarely have seen it. I personally, who have specialized in HSV for 40 years now, have seen one patient who reported a history of oral cold sores who had a positive swab test from the genitals subsequently. I also have had one patient report that to me online.

We don't have data on the reduction of transmission through the use of antiviral medication. The thing is, people who have HSV 1 genitally recur so infrequently and shed infrequently, that is likely offers only minimal benefit.

We do know that people who have genital HSV 1 for at least two years shed virus about 4 days out of the year. This is the work of Dr. Christine Johnston at the University of Washington and she presented this data at the ISSTDR meeting in Canada about four years ago.

I am assuming that you have had a test for HSV 1 and are negative for HSV 1? Or are you positive for HSV 1 and wondering if you will acquire this genitally? Remember if you test negative that the IgG test for HSV 1 misses 30% of HSV 1 infections compared to the gold standard western blot.

Terri

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38 months ago

Hi Terri,

Thanks for your thoughtful reply.

Could you give me a sense of the risk of contracting HSV-1 in my genitals on those 4 days out of the year during which my partner is asymptomatically shedding? If we have sex (let's say with condoms) on those days, is it more likely than not that I contract genital HSV-1? Or does the disease often not transfer even when it has an opportunity? Because although 4/365 days isn't many, for a couple having sex every other day that sounds like a recipe for infection after 1-2 years.

My last question would be - can you quantify at all what proportion of people with genital HSV-1 always remain asymptomatic? I realize this is probably hard to say but maybe you have a best guess.

Thanks so much Terri!

Terri Warren, RN, Nurse Practitioner

38 months ago

I don't know the portion of people with genital HSV 1 that are asymptomatic. Probably most after first infection.

And I don't have an estimate of how likely transmission is after two years of being infected, except to see that I have yet to see someone acquire HSV 1 through intercourse (that is, they had at least received oral sex in the previous 2 weeks.) It is really uncommon. It would be far more likely to acquire HSV 1 genitally from someone who is infected with HSV 1 orally, with or without symptoms, which is half the population. Just to put it in perspective

Terri

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