Wow.
First. HIV is comparatively hard to catch; Hep A/B are a lot easier, Hep C somewhat easier. Not to get crude about this, but given that Hep A has a fecal/oral transmission route and Hep B is easy to catch from exposures to small amounts of blood, get the Hep A/B vaccine. Three shots, months apart, a lifetime of protection.
Now, let's talk numbers.
For about the last ten years, studies on HIV exposure in buttsecks have consistently estimated your risk of infection from a *single episode* of taking a load up your ass at 1.4%. Meaning, if 100,000 guys take a load from a known-poz guy who is not in treatment, 1400 of them will be infected.
So, just on the odds, if you'd taken his load raw, you'd be looking at a 98.6% likelihood that everything is fine.
You didn't take his load. If protection is as little as 90% effective, that would cut the rate to .14%, or a 99.86% chance everything is fine. Or, in those 100,000 guys, 140 or so would be infected.
He says he's on HAART and undetectable. There've been a bunch of studies on that case recently. The benefits of treatment are estimated to be somewhere between a 96% and 99.9% reduction in risk from a single load.
What this means to you is that of those 100,000 guys? The worst case is 6 infections, the more optimistic number is less than 1. In fact, to get a 50:50 chance of a *single* guy in a group getting infected from a single encounter with a poz guy ejaculating in their ass with a condom, you'd need something close to 250,000 guys to each be exposed. And that's with a low factor of protection. Boost the condom to 99% efficacy, and you'd be at 2.5 million safe encounters with a HAART-treated poz guy who is undetectable before you hit 50:50 odds that *one* got infected.
So,OP, you should feel OK about your odds. Test on your regular schedule, but there's essentially zero chance this was a problem.
Incidentally, these numbers aren't out of my ass:
Baggaley RF et al. HIV transmission risk through anal intercourse: systematic review, meta-analysis and implications for HIV prevention. Int J Epidemiol (online edition), doi:10.1093/ije/dyq057
Grulich AE and Zablotska I. Commentary: Probability of HIV transmission through anal intercourse. Int J Epidemiol (online edition), doi:10.1093/ije/dyq101
Now, about PEP: for *semen* from a known-poz partner, if therapy is started within 72 hours (and 24 is better!), you can probably reduce transmission risk by about 75%. But let's look at what that means....
If those same 100,000 guys each took a load from a HAART user, raw, the estimated rate of infection would be .0011%, or, 1.1 conversions. PEP would drop that rate to 0.000825. So, for everybody saying you should run out and get PEP, I'd say "Wow, is it really worth the wear and tear on your body and the substantial expense to go from a 99.9989% chance that everything is fine to a 99.999175 chance?"
It's your body, you can make your own decisions, but from what poz friends tell me about HAART, it's no picnic. One swears he thinks he'll never take a solid dump again.
Needlesticks are a whole 'nother ballgame, whether from sharing works or occupational exposures. And repeated exposures change the game, too: 1000 loads from the same poz partner would raise the risk of infection to 46.5% with HAART and 1.1% without, and it may be legit to take PrEP (pre-exposure prophylaxis), if you're going to be in a relationship where you take it raw with a known-poz partner who isn't great about taking their meds regularly. Studies aren't conclusive yet, but among people who take the meds near-perfectly *before exposure*, it's 99%+ effective at preventing infection. Again, side effect and expense are very real.
Play safe, have open and honest discussions about sexual health, but don't freak out too much. In urban areas, adult gay men have infection rates well over 20%. If it were easy to catch, there simply wouldn't be any uninfected gay men...or, for that matter, many gay men left at all. Odds are pretty good that someone you find attractive and interesting and enticing is gonna be poz, and not all of them are douchecanoes like this one. Don't write them all off - just the asshats.
E