OK, I heard back from my reserach colleagues (two of them, actually). They don't materially change my opinion or advice above, but allow me to add some detail.
First, your wording seems to imply your sexual exposure 7 days earlier was oral only, i.e. your penis or vulva was not exposed (you don't say your or your partner's sex). If so, my reply stands. If also was there was genital or anal exposure, it is possible you also have genital HSV-2. Not particularly likely in the absence of symptoms, but possible.
Second, in the main research study that is relevant, my colleagues studied 50 HIV negative men with HSV-2. (There were also 102 HIV positive men, but those results probably not relevant if you aren't HIV infected.) The men were tested daily for 2 months for asymptomatic viral shedding from both mouth and genitals. Oral HSV-2 was detected 2.3% of the time (148 positives among 6,422 daily oral swabs) and genital HSV-2 17% of the time (1,110 of 6,505). All oral shedding was asymptomatic; nobody had an oral herpes outbreak during the 2-month follow-up period, even though many men had genital outbreaks.
The general conclusion confirms that recurrent outbreaks of oral herpes (i.e., cold sores) are rare in people with oral HSV-2; and that asymptomatic oral shedding of the virus is only one fifth as frequent as genital shedding. This probably translates to a low risk of mouth-to-genital HSV-2 transmission and transmission by kissing. Although the transmission risk probably isn't zero, in the real world this is extremely uncommon; in 30+ years in the STD business, I have never seen or heard of a case of genital HSV-2 acquired from oral sex, or of any case of oral HSV-2 from kissing.
Unfortunately, however, it isn't possible to know for sure that these results apply in your case. Unlike you, most men in the study -- probably all of them -- had genital HSV-2 along with oral. Further, most of those with oral infection did not have histories like yours, i.e. a prominent, symptomatic initial oral HSV-2 infection. Therefore, it isn't possible to be certain that the general conclusions of this research apply in your case. For genital herpes, the frequency of recurrent outbreaks and asymptomatic shedding is highest in people who have severe initial infections. If that applies to oral infection, your chance of oral outbreaks and of oral shedding of the virus might be higher than in the study.
The research study abstract is at http://www.ncbi.nlm.nih.gov/pubmed/16845624
I'm sorry for your unpleasant situation and will try to help. The diagnosis of oral HSV-2 seems solid. The good news is that when people get oral HSV-2, that's usually the end of it, once the initial infection resolves. Recurrent oral herpes due to HSV-2 appears to be rare. There are only a couple of not-very-definitive research studies on this, but most likely you will have few or no recurrent outbreaks. On the other hand, the frequency of ongoing asymptomatic viral shedding -- i.e. the potential for transmitting to partners by oral contact in the absence of symptoms -- has not been well studied and is harder to predict.
To your specific questions:
This is clearly a primary infection. Recurrent herpes rarely if ever behaves as you describe. Your exposure most likely was 3-10 days before onset of the first symptom; the 7 day oral sex exposure is by far the best bet. However, the incubation period can be as long as 3 weeks.
You can be sure you didn't get this by kissing. However, it is probable you were incubating the infection 3 days before symptoms and might have been highly infectious. Although HSV-2 is rarely transmitted by kissing, you should inform your kissing parter of the exposure so s/he can be on the lookout for symptoms and seek care promptly if they appear.
As implied above, I can't give you any advice about the risk of future transmission. Obviously you could transmit it if you have recurrent oral outbreaks, but that's not very likely. I'm going to email a colleague who has done the latest research on such issues (some of it not yet published) and will let you know if she has more defiitive advice.
If your genital area was not exposed during the same sexual event that included the oral exposure, and especially if you have had no symptoms of genital herpes, you can be quite certain you don't have genital HSV-2. Because cases like yours are rare, I can't quote scientific evidence of this -- but if I were in your situation, knowing what I know, I would be confident that no genital infection was present and would make my sexual choices accordingly.
Best wishes. I'll try to get back with more information after I contact my research colleague.
HHH, MD
It is quite possible for a lab to mistakenly identify HSV-2 versus HSV-1, and vice versa. It's not common, but it seems possible in this case; i.e., you may well have had an initial oral HSV-1 infection instead of HSV-2. Or your partner indeed has an early HSV-2 infection, or is one of those rare people with HSV-2 but negative blood test.
Speak with your provider about it; there is a possibility the laboratory still has the virus saved and can re-check the type. If not, you can have an HSV blood test to sort it out. If you go that route, have an initial test ASAP, then another one after several weeks. If negative for either virus type the first time, but positive on retesting, it will indicate a new infection with that virus type.
I'm not sure I'm entitled to a follow-up at this point (and no response expected), but strange turn of events: The person we both assumed I got this from (T-7 oral sex exposure) got her serum test results, and is positive for HSV-1 but negative for HSV-2. So either she has a brand new, entirely asymptomatic HSV-2 infection (which seems WAY unlikely given circumstances), or... or I don't know. This is one of those situations where no one has any reason to fabricate history.
Gotta say, this is making less sense all the time. (And yes, we also had vaginal intercourse, and no, I haven't had a single genital symptom despite watching like a paranoid hawk...)
At this point, it probably shouldn't matter to me what I have, but I'm wondering if the lab screwed up my culture.
Thanks for the thanks. It's an important issue, if somewhat uncommon on the forum.
Even 3 weeks would be unusual and 40 days is far too long. You can safely assume it was the 7 day event and you should discuss it with that partner with the near certainty that s/he is the source of your infection. If not already known to have genital herpes, s/he needs to see a provider for diagnosis.
Thanks, a remarkably thorough answer. I have other questions, but you've done more than enough, so I'll only ask one (since it has very small scale public health implications): you said I could have picked this up as long as 3 weeks ago. Does that mean that a different oral sex exposure 40 days before symptoms is just an unlikely source of my infection, or a statistically impossible one?