Congratulations on your safe sex practices. There is certainly no risk for STI, including HIV, from sharing a tub, receipt of a body slide or masturbation, or receipt of condom protected oral or vaginal sex.  Further, your partners were relatively low risk despite her profession- she is tested regularly, practices condom protected sex, and is more cognizant of her risk and measures to avoid infection that other more casual partners.  The fact that she touched the inside of the condom before putting it on your penis is a no risk event, even if she had touched her genitalia prior to doing so,  No STIs are transmitted through transfer of infectious material on a persons hand to another person, either directly (as might occur with masturbation) or indirectly as might happen in the situation you describe.  I would not be worried in the least and in fact, see no medical or scientific reason for testing at this time.  

I hope that this perspective is helpful.  EWH 

1. I woke up today feeling a sore throat and perhaps a mild fever coming on. It has been less than 48 hours since the sexual encounter. Is this indicative of anything related to the encounter, or more likely a result of lack of sleep/a common cold coming on? (clarification: I did not perform oral sex on the CSW)

2. I’m curious as to why online resources seem to indicate that condoms are only about 90% effective in preventing HIV transmission - this seems to indicate a 1 in 10 chance, though I assume from other readings that this is not the case. 

Thanks so much for your expertise and the work you do on here! 

1.  48 hours is too soon for the onset of symptoms due to any STI including HIV. Thus these symptoms are further evidence that your symptoms are unrelated to the encounter you described.  As you know, flu-like illnesses are common in travelers.

2.  The 90% figure rate for condom. Success relates to the fact that many people use them incorrectly, putting them on after they’ve begun to have sex or other errors and use. As long as you were a condom was worn throughout the encounter from beginning to end it did not break. You can be confident that it protected you from STI.  Again that your partner touched the inside of the condom is no misuse.

Please don’t worry.

EWH