I'm glad to have helped. Take care and stay safe.
Thank you very much for the explanations. I got it ;-)
"Could be" you catch HIV in such a circumstance? Sure. You also may be struck by a meteorite someday.
I think you misunderstood my analysis above. The 1 in 20,000 risk is for a partner known to have HIV. In South America, I would guess that on average the chance any particular sex worker has HIV probably is no higher than 1% (1 chance in 100). So your actual risks from the exposure described is 1 in 200,000. Zero for all practical purposes. I'll be nobody in the world has EVER acquired HIV in the circumstnaces you describe, and I see no reason to worry that you would be the first.
Nobody has calculated the syphilis risks in this situation. It's probably higher than for HIV, but still low. And if you acquired syphilis, you could expect a typical chancre (sore) where your penis was exposed. If nothing like that shows up by 3-4 weeks after the event, you can safely conclude you didn't catch syphilis.
If you remain nervous despite this reasoned, science-based reassurance, you of course are free to be tested for HIV and syphilis in a few weeks. Assuming you have had no other exposures and develop no syphilis symptoms, you can be confident the results will be negative.
Ok, I see!
But for HIV, it means also that if you are unlucky and have receiving oral sex with a HIV-positiv person, it could be that you catch HIV with the first exposure, isn`t it.
By the way, the girl was from south america and she she work sometimes as sexworker. So, therefore the risk is higher, isn`t it?
Do you have any estimate (or statistical) risk for syphilis if anyone performs oral sex?
Thanks a lot
Welcome back to the forum. You had a few question on this and the HIV prevention forum a few years ago, but none since then. I'm happy to help this time as well.
Oral sex is safe sex. It isn't totally risk free, but the chance of catching HIV or other STDs by oral to penile transmission is low, certainly much lower than for unprotected vaginal or anal sex. As for HIV, it may or may not be truly zero risk -- but the maximum calculated risk is around once for every 20,000 exposures, which is equivalent to having BJs by infected partners once daily for 55 years before infection might be likely. And your risk is lower still, since so few heterosexual women from Europe have HIV.
The risk of other STDs is a bit higher, but still low. And most STDs acquired by oral to penile exposure would cause symptoms. In other words, if within a couple of weeks you haven't had abnormal discharge of mucus or pus from the penis, and no penile blisters or sore, you can safely conclude you weren't infected. I don't recommend testing at all if you don't have such symptoms. But if you want complete reassurance, you could have a urine test for gonorrhea any time more than 2-3 days after exposure, and a blood test for syphilis at 6 weeks. (Chlamydia is almost never acquired by oral sex, but testing is usually automatic whenever gonorrhea testing is done.)
In other words, if I were in your circumstances, I wouldn't be at all worried and in the absence of symptoms I would feel no need for testing.
I hope this has helped. Best wishes-- HHH, MD