# Statistical Herpes QuestionApril 9, 2014 6:50 AM   Subscribe

Can you give an estimate of the likelihood of contracting herpes based on this scenario?

Not looking for opinions, but educated guesstimates would be helpful.

What is the likelihood of a man contracting genital herpes from one evening of vaginal sex with a woman provided he is wearing a condom and she reports no outbreaks in 10 years and is taking daily Valtrex?

I'm pretty sure it's astronomically low. I'm seeing numbers like 2% of men would contract herpes in this situation from a year of sex in a committed relationship. But if someone had some more specific ideas I'd appreciate it.

If you could stick to the question and not have this be a general discussion about herpes, sex, etc that would be great.

Thanks
posted by mockpuppet to Health & Fitness (10 answers total)

I think that the only statistic that should matter to you is "non-zero".

You should talk to a doctor.
posted by DWRoelands at 7:33 AM on April 9, 2014 [5 favorites]

Can't provide you a number, only anecdata: A friend of mine was married to a woman for 10 years who had occasional outbreaks (they would avoid sex during outbreaks), they never used condoms, and after they divorced he got tested and was negative. So I think you're probably fine.
posted by greta simone at 7:38 AM on April 9, 2014

Accepting that 2% number (I'm not sure I do) and assuming that committed couple will have sex ~100 times/year, the simple, stupidest probability would suggest that once should have a probability of ~0.02%.
posted by Betelgeuse at 8:02 AM on April 9, 2014

2% can be reasonably used as a ceiling for the probability of the act you described, meaning your likelihood is definitely less than or equal to 2%, but how much less than 2% cannot be derived from the statistic (sorry Betelguy).

The scenario you've described includes pretty much everything we would want it to in order to minimize the risk of the sex act, except that you would also want to know that the man in question isn't immunocompromised (e.g. by AIDS, immunosuppressant drugs, etc). I have done a fair amount of reading and research on the subject in the past and I have never seen a study that produced the specific statistic you're looking for because it is, as you said, astronomically improbable.
posted by telegraph at 8:12 AM on April 9, 2014

So telegraph. Statistically you're saying that it's somewhere between 2% and infinitely small? Or am I misreading you? Or just ignorant of statistics?
posted by mockpuppet at 8:44 AM on April 9, 2014

It doesn't matter what the statistics are if you end up being the unlikely exception. It's not that likely, but it could happen. Happened to someone I knew, even. You can't 100% be in the clear, and if you tend to be naturally paranoid you're just going to keep wondering about it anyway. Sorry.
posted by jenfullmoon at 11:48 AM on April 9, 2014

Without controlling for condom use or antiviral therapy, "the rate of infection per 10,000 sex acts was 8.9 and 1.5 for susceptible women and men, respectively." I'd say significantly less than 0.0000015%.

It's also worth noting that 1 in 4 women in the U.S. have herpes, and most are unaware, so the risk with the general population isn't actually zero either.
posted by susanvance at 4:03 PM on April 9, 2014 [1 favorite]

Yes mockpuppet. That is exactly what I meant.
posted by telegraph at 12:27 PM on April 10, 2014

Can you give us a little more information? If you're happy with "between 2% and infinitesimally small" then that's fine, but I feel like I can't answer this question appropriately unless I know why it would make a difference to you to know whether the likelihood is 0.2% or 1%, for example.

Because without further information, the question reads as if you're asking permission/trying to give yourself permission not to get tested for herpes if the odds are low enough, but that question is really a question about your own risk tolerance (and the risk tolerance of any other sex partners you have currently or in the future) as well.

I know you asked us not to discuss anything but numbers, but since there is no calculator we can use to work out the risk of your specific situation, the context is meaningful.
posted by treehorn+bunny at 1:37 PM on April 11, 2014

Treehorn,

I think the situation as described is pretty clear, no?

As far as I can figure, the chance of transmission from this 1 sex act is much less likely than the man actually being a symptomless carrier of Herpes to begin with? Which appears to be approximately 17%?
posted by mockpuppet at 7:07 AM on April 16, 2014

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