Question about infection odds

[sp78]

Hello Dr. HHH,

I am a 27 year old male, currently working in New York City.  I recently had an unprotected vaginal sex with, whom I thought was only going to give me an exotic massage.  Yes, I went to a Korean massage parlor in the city, and quickly found out that exotic massage wasn't the only service they provided.  Had I known this fact before, I would have never jeopardized my life like I did.  To make the long story short, I ended up having unprotected sex with 25 year old Korean girl for about 5 minutes, and I ejaculated inside her.  It was only then, that I realized how foolish I was, and quickly became concerned about possibility of being infected with various STD's, including HIV.  The girl told that she's only been prostituing for a few months, and that before she came to the US in mid-2005, worked as a secretary in Seoul, Korea.

I read your helpful advises posted on varous STD threads, and I just have two questions.

1)  You've mentioned, on numerous occasions, that the odds of getting infected with HIV through a single occasion of UNprotected vaginal intercourse is about 1 to 1,000 (assuming the partner is HIV positive).  This was certainly a relieving statistics, but I'm still wondering why HIV is so hard to transmit from one to another.  Is it because the virus is not always present in vaginal secretion, or semen?  

2)  Also, I found an interesting article on about.com, which talks about the likelihood of HIV infection through various unprotected sex acts.  In my case (assuming that my partner was HIV +... God forbid!), they claim the odds are 1 to 200,000.  I'd say both 1 to 1,000 and 1 to 200,000 are relatively low risk, but I'm just wondering where the differences are coming from.  Would you say 1 to 1,000 is more likely?  

http://aids.about.com/od/hivaidsstats/f/infectionrisk.htm

Regardless of what your answers are, I perfectly realize that I've exposed myself to the risk, and I will get tested in 4-6 weeks to be reassured.  I guess all I can do for now is just focus on what's happening in my life, live a healthy life style, and don't be paranoid about HIV, because the odds are strongly in favor of me...  (As you can tell, I'm just trying to comfort myself, and I am VERY worried =(  )

Thanks in advance, Doctor.

Regards,......sp78

[H. Hunter Handsfield, M.D.]

You believe you "jeopardized your life" by having a single episode of sex with a commercial sex worker?  Get real!  Not meaning to trivialize your concern, if that exposure was a significant risk, AIDS would be 100 times more common than it is.  Anyway, HIV is pretty uncommon in Korea--and in general is less common in most commercial sex workers than in non-commercial sexually active persons.

1) It is simply a biological fact that HIV is hard to transmit.  Not all infections are transmitted with equal efficiency.  For example, to get infected with salmonella, a common bacteria that causes food poisoning, a person has to swallow 50,000 to 100,000 salmonella bacteria. To catch shigellosis, a similar diarrheal disease, only 50 shigella organisms is sufficient to infect most people, a 1000-fold difference.  Likewise, it takes up to a million more HIV viruses to result in HIV transmission than for hepatitis B.  HIV probably is always present in the genital secretions of infected people; but most of their partners imply are not exposed to enough HIV for infection to "take".

2) The actual risk from unprotected vaginal sex is half what you say, closer to 1 in 2000.  The 1 in 1000 (or 2000) risk assumes the person has HIV.  The 1 in 200,000 factors in the probability that she doesn't.

Anyway, you don't need to worry much about the exposure you describe.  Best wishes--  HHH, MD

[Willl]

The 1 in 200,000 may be the odds of getting it if you were randomly selecting women from the general population to have sex with. I don't think those odds would apply if you were having sex with a woman known to be positive. If you have sex every day with an infected person for 50 years that would be 18,250 exposures. So by the 1/200,000 odds, it would be very unlikely to have acquired HIV after all that. Which I do not believe for a second.

[Confused_again]

Hey dude.. check out this link..maybe you'll find some comfort...Hopefully you'll be fine.. http://www.thebody.com/Forums/AIDS/SafeSex/Current/Q171648.html

[H. Hunter Handsfield, M.D.]

Thanks to confused_again for the link to a recent question at Thebody.com.  Dr. Frascino's ("Dr. Bob") advice on HIV transmission and safe sex is excellent.  Some people who have visited both this forum and that one have tried to find differences between us, and in a couple of instances my comments here were taken out of context, leading to apparent differences of opinion between us.  But in fact, there is virtually no difference in our risk assessment or advice to similar questions.  Dr. Bob's style and mine are different, but that's pretty much where it ends.

HHH, MD

[Confused_again]

I can't seem to find any studies that indicate the estimated risk for contracting HIV from a single episode of anal sex with a female. What are the odds for the male and the female? Anyone knows the answer to this?

[H. Hunter Handsfield, M.D.]

I doubt any such data exist.  But there is no reason to believe it is different than anal sex with a male, except that fewer women than gay men are HIV infected.

HHH, MD

[kkbb]

I am a 45 year old (married) male and over the past months I have been going to an exotic bath house.  Besides the bath I usually would have the Korean lady (same one every time) masturbate me.  Well, unexpectedly during my last visit she just got on top of me and inserted my penis.  Rather than stopping I continued to have a 15 minute sexual unprotected encounter that even included mutual oral sex.  After it was over she told me I had no worries (STD I guess she was not specific and I did not ask) and that she had sex becasue she liked me as more than a client and would miss me as she was leaving town.  Now I am worried.  When she only touched me with her hand, I was not worried about STD's but now I've gone too far and I am worried about my odds of infection.  I have read other posts and articles, but I guess I am looking for some reassurance that my odds of infection are low.  Of course, I still have the issue of telling my wife, which I must do, as I am going to obstain from sex with her until I get tested.  How long should I wait for testing?  Thank you very much for your help.

[taffee1]

A related discussion, scared and worried was started.