Although Thailand once had very high HIV rates in female sex workers, the national response was amazingly good and resulted in marked improvement. Today, HIV is uncommon in Thai women, including sex workers. Hepatitis B virus (HBV) infection also is  uncommon, since most Thai residents are immunized against HBV. And contrary to popular beliefs, the hepatitis C virus (HCV) is not heteroseually transmitted -- or so rarely that it can be ignored. (One recent analysis calculated the risk for unprotected vaginal sex at 1 chance in 190,000, if one partner has HCV.

Also, even if your partner(s) had HIV, the chance of transmission during any single episode of unprotected vaginal sex averages once for every 2,500 exposures. That's equivalent to having unprotected sex once daily with infected women before catching HIV might be likely. Further, their negative tests make it almost possible these women had HIV (same for the other infections you listed). In theory, they could have been in the window after nex infection and test positivity, but statistically this is exceedingly unlikely. For these reasons, I'm glad you didn't continue with PEP. I would have recommended against PEP even if your partners were not tested for HIV, unless you knew certainly that one of them was infected.

Based on all this, I really don't see any need for you to have any of the tests you have listed, either at 10 days, 30 days, or any other time. However, if you wish to follow through with testing, I would advise waiting until 6 weeks after the events, and at that time have an HIV Ag/Ab test and maybe also another HBV panel. It truly would be a waste of money to have an HCV test.

As for syphilis, that also is extremely unlikely in absence of an obvioius primary syphilis sore (chancre), which usually is readily apparent on the penis in this situation. It can take up to 3 weeks to show up, but assuming nothing appears, the likelihood of syphilis is very low. That said, it would be reasonable to have another syphilits blood test 6 weeks after the event -- but no sooner than that.

Finally, you don't mention gonorrhea or chlamydia, the two most likely STDs in this situation. Have you been tested for them? Gonorrhea almost always causes obvious symptoms (penile discharge, painful urination) within 5 days of exposure. But chlamydia is often asymptomatic, so it would be reasonable to be tested. The urine test for gonorrhea/chlamydia is valid any time more than 3-4 days after exposure.

These comments should be reassuring; I hope they are! Let me know if anything isn't clear.

HHH, MD

Your response is indeed reassuring. As you would suspect I have been pasting this query in several free and paid forums, only to get very contradictory advice. Some say as per CDC guidelines I am at high risk and some say I am at no risk atall without much explanation.

I had a long conversation with these women with regards to why that evening went unprotected and whether that is their general level of carefulness. It was a candid discussion on how they too were inebriated on several substances that evening and as floozy as it may sound, it wasn't a typical commercial arrangement as we did exchange a lot of thought and ideas. I was able to extract from them that it was very rare for both of them. Both had not had unprotected sex with a client in over 3 months and one of them was also tested negative around 3 months ago. I chose not to include that in my original post as it is information of dubious integrity, although I may personally trust it.

With regards to gonnohrhea, I figured I would get tested for that and Chlamydia in a complete screen at 4 weeks. Since the treatment is simply a course of antibiotics.

So, should I push my comprehensive STI screen from 4 week from exposure to 6 weeks? And can I consider that conclusive and move on?

I really appreciate the work you are doing and have gained a new perspective on life due to this entire ordeal.

Thank you

It sounds like your partners are unlikely to have active STDs, although certainly the expousures were not risk free.

And yes, I think it's fine to delay your next assessment to the 6 week mark, assuming no symptoms appear between now and then. Avoid sex with anyone else in the meantime -- or at a minimum use condoms and let partner(s) know the situation.