[Question #399] Asymptomatic HSV 1 Transmission Rates

34 months ago
I am a 40 year old woman who is positive for HSV 1 (iGg test). I've been tested three times over the last two years after separating from a partner who had both oral and genital herpes with regular visible outbreaks (confirmed as HSV 1 orally and HSV 2 genitally). However, I am asymptomatic and hadn't been tested prior to this, so I have no idea whether my HSV 1 is oral or genital or when I got it (my mother has oral herpes, and I've had friends and boyfriends with oral and/or genital herpes in the past).

I am now sexually active with a man who does not have either HSV 1 or HSV 2 (he’s in his thirties). We are understandably paranoid about him getting HSV 1 from me, but I am having a hard time finding information on transmission rates for asymptomatic HSV 1, and find what is available to be really confusing. For example, I've read that the likelihood of transmission is less than 1%, but at the same time I've read that up to 60% of people in the US have HSV 1, and 50% of new cases of genital herpes are from HSV 1 from oral to genital contact and that transmission can be more common when there are no visible sores (I'm guessing because people with visible sores abstain from sexual contact during the outbreak whereas people without symptoms don't know when the virus is shedding).

My current sexual partner and I have vaginal and anal intercourse using condoms, but we abstain from kissing, he does not perform oral sex on me, and I only occasionally perform oral sex on him (and always with a condom) as I am very concerned about my saliva coming into contact with exposed areas of his genitals. I am also concerned about vaginal fluids touching those areas not covered by the condom. Abstaining from kissing and oral sex and the near constant worry about giving him HSV 1 is very challenging. I’ve asked my doctor about going on a suppressive antiviral therapy drug, but she said it’s not recommended for asymptomatic HSV 1 cases.

My question is - what are the transmission rates for asymptomatic HSV 1 for the following?

1. Kissing
2. Oral sex (giving and receiving; with and without a condom or dental dam)
3. Intercourse (with and without a condom)

Thank you.
Terri Warren, RN, Nurse Practitioner
Terri Warren, RN, Nurse Practitioner
34 months ago
Hi Jane,
First let me ask you this:  how to you know that your current partner does not have HSV 1?  Has he actually been tested to determine that?
All of the statistics that you quote are accurate, with a few explanations.
Genital HSV 1 sheds far less than HSV 2 genital infection.  We think that HSV 1 shed on about 15-20 days out of the year.  Yes, about 60% of the US population between 14 and 49 have HSV 1 infection and yes, about half the new cases of genital herpes now are caused by HSV 1. 
We do not have statistics on transmission of HSV 1 in any of the scenarios that you ask about.  I'm so sorry.
It must be challenging, I would think, to have anal sex with someone you don't kiss.  It just must be difficult not to kiss your partner! 
In my personal opinion, if he has not been tested, he should be  And remember that the usual IgG screening test for HSV 1 misses one of four infections, compared to the gold standard western blot.  Second, I would like to know your index value for HSV 1 on your IgG test.  Third, remember that oral herpes can also present in your nose or chin as well as on your lip. 
It is also important to remember that this man has likely had sex with more than one person who has HSV 1 infection and didn't know it, given the prevalence of this infection.  And then one must ask oneself, is it worth the things are you are going through not to risk transmitting this virus?  If you were my patient, I would also strongly recommend that you go on daily suppression to reduce the risk of transmission.    Please let me know what other questions you might have, Jane.

Terri
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34 months ago
Hi Terri,

Thank you for your quick response, although it's disheartening to find out the reason I haven't been able to find reliable info on asymptomatic HSV 1 transmission rates is that there isn't any.

To answer your questions:

1. My current partner was tested for HSV (he doesn't remember the specific test) within the last three to four years, prior to entering into his last relationship (which was monogamous), and tested negative for both types.

2. My index value for HSV 1 was 5.37 in 2014 and 5.27 in 2015 (tests taken approximately one year apart). I was also tested about midway between those two dates, in early 2015, but I don't have the index value from those results (was only verbally told yes to HSV 1 and no to HSV 2).

To your comment regarding oral herpes presenting on your nose or chin, I don't remember ever having any suspicious or even non-suspicious sores, blisters, or bumps anywhere on my nose, chin, mouth, lips, or genitals.

You stated that genital HSV 1 sheds far less than HSV 2 genital infection (roughly 15-20 days/year). How often do asymptomatic HSV 1 oral infections shed (days/year)?

You also said if I were your patient you would strongly recommend I go on daily suppressive therapy to reduce the risk of transmission, but I've read that daily suppressive therapy is not recommended for asymptomatic HSV 1 and efficacy studies have not been done on DST for HSV 1 or for asymptomatic shedding (other than some studies showing DST does reduce the presence of HSV1 in saliva)? My doctor has said no to putting me on DST because I'm not symptomatic and it's not HSV 2, but if there is a benefit (and it seems like common sense would say there is), I will ask her again or find another doctor. Although even if I were to go on DST, and it makes me feel less anxious about saliva and genital fluids getting on those parts of his genitals not covered by a condom, I'm guessing it doesn't suppress the virus enough to make unprotected kissing or contact measurably safer?

I understand your point about asking myself whether going through the anxiety and abstaining from basic intimacies in a relationship is worth the risk of transmitting the virus, but I would say it has to be. I think, like most people, my acceptable level of risk when I'm the one who could contract something is much higher than what is acceptable when I'm the one potentially infecting someone else.

Thank you again,
Jane
Terri Warren, RN, Nurse Practitioner
Terri Warren, RN, Nurse Practitioner
34 months ago
So the thing about the testing for HSV 1 is that the test misses 1 out of 4 infections so if knowing his correct status is really important, I would suggest the western blot.  Your value is solid.  Our most recent research confirms that everyone in our study who tested at 3.0 or greater on the traditional IgG confirmed with western blot for HSV 1. 
HSV 1 orally sheds on 9-18% of days, depending upon the study that you read, and as with genital infections, people who have recognized outbreaks shed more often than those who are asymptomatic. 

When clinicians discuss the use of suppression for herpes, I don't think they fully take in consideration the data on viral shedding.  Long ago we recognized that in terms of transmission, the key element is shedding, not outbreaks.  We know that the antiviral medicines work well to suppress both HSV 1 and 2 but you are correct, there is no data on the reduction of genital HSV 1 viral shedding while on suppression.  That's not easy to measure given the lack of overall shedding genitally.  We know it is very successful at reducing oral shedding of HSV 1 and is used routinely for people who have herpes of the eye to reduce viral activity.  I think we can extrapolate pretty correctly from that data.  But no, we don't get shedding to zero with these medicines.

Terri
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34 months ago
Thank you, Terri. Final question - you said the antivirals have been "very successful at reducing oral shedding of HSV 1." Do you know by what percentage? More or less than 50%? I understand there is no data on the reduction of genital HSV 1 viral shedding while on suppression, but it is safe to assume it would be roughly the same percentage as for oral shedding reduction? Thank you again for all the information. It has been very helpful.
Terri Warren, RN, Nurse Practitioner
Terri Warren, RN, Nurse Practitioner
34 months ago
I don't have an exact percentage, Jane, no, I'm so sorry.  I should have more accurately said it is effective at reducing the frequency of oral outbreaks rather than viral shedding, which is more accurate.  I'm not clear that there are research studies about this, but I have a lot of people on suppression for cold sores who suppress quite completely. 

Terri
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34 months ago
Sorry, Terri, but to be clear, you're saying that antivirals reduce viral outbreaks, but while there isn't any data showing they suppress shedding, it is assumed they do which is why you'd recommend antivirals for asymptomatic HSV 1? Thanks.
34 months ago
And when you mentioned the average percentage of days HSV 1 is shed orally or genitally, you meant shedding and not outbreaks, correct? Sorry, just want to be clear. Thank you again!
Terri Warren, RN, Nurse Practitioner
Terri Warren, RN, Nurse Practitioner
34 months ago
Yes, I meant shedding, not outbreaks.
Yes we know that antivirals reduce both shedding and outbreaks.  This is why we prescribe suppressive therapy for people who are HSV 2 positive but have no recognized outbreaks and are having sex with someone who is HSV 2 negative.  I know here we are talking about HSV 1 but the principle, I believe, is the same. 

Terri

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