How do you get herpes?
October 4, 2010 1:45 PM   Subscribe

I need to know the difference between HS-1 and HS-2 and if I am at risk for getting herpes on my mouth.

Posting anonymously because my recent ex frequents here and knows my handle, which could cause certain problems that I'm sure will reveal themselves shortly.

I went home with a girl last night -- it was the first time I'd done so in 3+ years, so the whole thing is a bit new for me -- and I find myself still utterly clueless about herpes (I'm 25, and healthy as far as I know). We used a condom when we had sex, but before we did, I went down on her for a few minutes. I'm worried about the possibility of getting "mouth herpes," which I know is HS-1, but don't know if she could've given it to me if she did have HS-2.

It was very dark and I was very drunk, but from what I could tell she had nothing resembling sores down there -- if anything it appeared a very well-maintained, herpes-free zone. But I'm still scared, simply because I don't know the mechanics of transmission.

Do I (does everybody) already have HS-1? (I've had cold sores before, but they're always on the corner of my mouth, and always very small; is that a herpe)?

If I don't have it, could I have gotten it from performing oral sex on her?

Hopefully the hive mind can clear this up. I feel woefully uneducated about this thing; it's a sad state of affairs. Thanks!
posted by anonymous to Health & Fitness (11 answers total) 1 user marked this as a favorite

A majority of people have oral HS1 - Yes, "cold sores" count (though what you describe could just involve cracked lips - Do you get a sort of tingly/numb small blister prior to the sore, or does it just appear suddenly as a broken spot of skin/lip?).

You can get HS2 orally, and you can get HS1 genitally.

If she didn't have any active sores, then you have almost no risk of getting it (though non-zero).
posted by pla at 1:55 PM on October 4, 2010

Warning: I have studied some virology, but I am NOT a medical doctor or medically qualified in any way. Talk to someone who is... I'm sure there's a free or subsidised sexual health clinic somewhere in your area.

HS-1 and HS-2 are similar but distinct flavours of the virus Herpes simplex. Generally, HS1 is much better at infecting around the mouth, and HS2 is better at infecting the genitals. It's not impossible to have and HS2 infection in your upper lip or an HS1 infection around your genitals, but it's relatively rare; for whatever reason, the two viruses prefer to stick to their familiar turf.

If you get cold sores they're almost certainly caused by your latent HS-1 infection flaring up in response to some sort of stress. Not everyone has it, but it's very common: basically everyone who gets cold sores, plus a load more who carry the dormant virus but are asymptomatic. It's irritating, but not harmful except in extremely rare cases, which are generally associated with another disease suppressing the immune system. So you're probably inefcted with HS-1, but don't worry about it too much. However, this comes with the rider that you might want to avoid putting your active cold sores anywhere near other people's broken skin or mucous membranes, to avoid spreading the infection.

Note that carrying a HS1 infection does not alter your chances of being infected with HS2. There's no protective immunity, and no extra susceptibility.

Generally speaking, for transmission to occur an active site of infection (i.e. a sore) needs to be shedding virus that comes into contact with broken skin or with your mucous membranes (e.g. your mouth, under your foreskin). Infection might be possible through unbroken skin but it's very inefficient, so you'd have to be quite unlucky for it to occur.

It's good that no sores were visible, but bear in mind that they can be very small, and occasionally be well hidden or camoflaged. You should certainly include a HS test in your normal post-sexual-activity health check but, based on what you've written, I doubt you need to worry about it too much.
posted by metaBugs at 2:14 PM on October 4, 2010 [2 favorites]

There is a ton of information about this at places like wikipedia. Yes, cold sores count as herpes, if what you get are, indeed, cold sores. Yes you could get herpes (and other STDs) from oral sex (both given and received).

Though HS-1 was originally thought of as "mouth herpes", both types are now commonly found on both mouths and genitals, so type isn't all that relevant. If neither she nor you had any obvious sores your risk is lessened, but not infinitesimal.
posted by ldthomps at 2:17 PM on October 4, 2010

I stand corrected on the differentiation between HS1 and HS2 by metaBugs' informative response.
posted by ldthomps at 2:20 PM on October 4, 2010

When herpes comes up on mefi there are often comments about how everyone has it, but just to add a bit of data to "A majority of people have oral HS1" --

frequency of hsv1 in the US is 58% and HSV2 is not even 1 in 4.
posted by rr at 2:26 PM on October 4, 2010

I know nothing will stop you freaking out right now, but wait a few weeks (I think my doctor said about a month, so any potential virus has time to "build up" in your system) and get a simple blood test. That will tell you whether you have Type 1 or Type 2 antibodies (or viral whatever) in your system. Although, as the doctor most likely will tell you, if you've had true cold sores/fever blisters on/near your mouth, you probably already have Type 1.
posted by mesha steele at 3:31 PM on October 4, 2010

Oh, and condoms don't fully protect against genital herpes transmission (or HPV for that matter), according to doctors and medical students I've spoken to, since the sores can be on parts of the body that are not covered by the condom. I don't have any specific statistics for transmission rates during condom-ed intercourse, though.
posted by mesha steele at 3:36 PM on October 4, 2010

It's possible I'm out-of-date, because virology changes fast, but I want to elaborate on metaBugs point about cross-immunity. There is some evidence that infection with HSV-1 provides some protective effect and may mediate severity of HSV-2 outbreaks. It does not seem to reduce infection rate. So...someone with HSV-1 is equally likely to contract HSV-2, but not as likely to get severe outbreaks, and therefore may be less likely to realize it. Viruses have a wily sense of humor like that.

I also believe that HSV-1 is responsible for a growing proportion of genital herpes in developed countries. (See 'Background' and the cites.) This may be due to the falling rates of HSV-1 infection in childhood, so oral-genital contact from an actively-shedding partner provides novel introduction of HSV-1, and...dang. (This is reflected in the fact that the populations with genital HSV-1 are generally women, minors, and men with same-sex partners.)

So I would not refer to it as 'rare.' The effect noted above about 'site preference' may have more to do with that cross-reactivity and mild protective effect.

Both of you should get tested in a month, especially if you know you have HSV-1.
posted by Uniformitarianism Now! at 4:13 PM on October 4, 2010

I mean--'are pretty sure you get cold sores, and therefore you suspect you already have HSV-1.'
posted by Uniformitarianism Now! at 4:16 PM on October 4, 2010

I am a herpesvirologist, though not your medical doctor. Most of what Uniformitarianism Now! and metaBugs are saying appears to be correct.

It does sound like you probably have an oral herpes infection, though of course I can't tell you for sure.

There is the possibility that if she had genital HSV-2 you could get an oral HSV-2 infection; however, on the bright side, HSV-2 is not as good as either establishing a permanent infection in the face or later reactivating.

The thing about cross protection - where having been exposed to HSV-1 keeps you from getting HSV-2 - is that it is going to vary somewhat from person to person and unfortunately, most of the data about cross protection comes from animal models and they don't always reflect what happens in humans (and some herpesvirologist think they are shit). If they did, we'd have a vaccine that worked (of course, we'd probably have that if the FDA would ease a few restrictions...).

One thing I want to point out is that just because you didn't see any sores does not mean she wasn't shedding virus. There is data showing that genital HSV-2 infection can reactivate and be shed, to at least a very limited degree, nearly constantly. This is without sores necessarily being formed.
posted by The Bishop of Turkey at 10:08 PM on October 4, 2010 [1 favorite]

Wait, so she had no symptoms and didn't tell you that she has herpes, and you're nervous because you wen down on her unprotected and you don't know her status for sure?

Yeah, it's technically possible that she has either hsv1 or hsv2 and was shedding and you caught it but the chances that all three of those things are true are pretty slim. If you're so worried about it, I'd think twice about having any kind of sex with anyone unless you knew for sure that they'd had a negative herpes blood test at least a month after their last intimate (even kissing) partner, protected or unprotected. And stay completely abstinent now and get yourself a blood test after a few months (one MD told me 3 weeks, another told me 3 months). That's a fair approach to sexual health if that's what you're comfortable with, and if you're freaking out after oral sex with someone with no symptoms when you've also had no symptoms, it's probably what you should be doing. It's definitely not the only approach though and I think it's not typical. You could definitely also consider just not worrying about it until/unless you get symptoms or she tells you that she has herpes or reason to think she might.
posted by Salamandrous at 1:00 AM on October 5, 2010 [1 favorite]

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