General Transmission questions

[MeowMix17]

Hi! First, I want to thank you for the endless words of wisdom and advice you have provided all of us readers over the years. I have come to this forum many, many times to clear up questions or calm fears and your thoughtful, honest answers are greatly appreciated. There are so many conflicting views on STD topics these days, it is a relief to have a compassionate and competent informant. So, THANKS for all you do!!!

Quick background:
I am a female, heterosexual who does not use drugs or partake in any risky behavior apart from unprotected sex with straight/non drug user males.

At my last STD test (in January 2007) I was negative for EVERYTHING. Since that time I have given unprotected oral and had unprotected vaginal sex with a few (1 oral ONLY,  2 vaginal + oral) guys, all of whom insisted they were negative of everything (I tend to harp on the issue and ask a lot so the assumption is they weren't lying). The only "symptoms" I have ever gotten were sore throat and vaginal itch and these occurred maybe a few weeks after one of the unprotected incidences. I took amoxycillin for the throat, which went away within a couple of days - doctor didn't say it looked like anything other than just a bad sore throat. The vaginal itch went away on its own as well within one week. (note: these two symptoms occurred separately and did not overlap).

Q1:
If I had unprotected sex with a male a couple of months AFTER sore throat/vaginal itch occurences, do you:
A)think those were related to STDs and
B) think that I could have transmitted an STD to the new guy?
How common are female-to-male STD transmissions?
We had sex four times total, would this be enough for risk to him if I tested positive      for anything?

Q2:
I have read statistics stating things such as various STDs having an

[H. Hunter Handsfield, M.D.]

I'm not sure where your 80% figure comes from.  There is no precision on risk of chlamydia transmission, but it's probably around 50% from male to female per episode of unprotected sex, if the male is infected.  But that figure probably varies widely, depending on various factors both known and merely guessed at:  whether the woman has previously been infected and might be partly immune, her age (younger is higher risk), maybe differences in personal susceptibility, and (as a guess) maybe differences from one chlamydia strain to another.  The general population transmission rate is much lower, because at any point in time, most potential sex partners are not infected.

Most STDs are transmitted more efficienty from male to female than the reverse.  If you think about it, it makes a lot of sense:  a woman leaves a sexual encounter with a dose of potentially infected secretions inside her body.

[MeowMix17]

Sorry - one last question. Is the female-to-male rate of transmission different from male-to-female? Just something I've wondered for a while since most information I read indicates that male to female is more common. Thanks again!

[MeowMix17]

Thanks! I'm not sure what happened to my original Q2 - it got cut off somehow...see below if you don't mind. Thanks a lot for the feedback on the first one! :)

Q2:
On STD transmission risks per acts percentages: If a person has an 80% chance of getting chlamydia from unprotected sex, is the 80% referring to a person's chance of getting it from a partner infected with chlamydia or the chance of getting in from taking part in unprotected sex in general? In other words, if a person has sex with a person with an STD, is the percent chance of acquiring that same STD based on the sex with the infected person or a general population acquisition rate?

Thanks again for your insight. I'll look forward to hearing from you.

[H. Hunter Handsfield, M.D.]

I should have added that vaginal itch is not usually an STD symptom; yeast infections and nonspecific minor irritation are more common explanations.  Everybody has genital and/or anal itching from time to time.  But if the itch is definitely unutual or if it reappears at something like every 1-4 months, with no symptoms at all between such events, examine yourself to make sure there aren't sores that could indicate herpes.  But that doesn't sound likely.

[H. Hunter Handsfield, M.D.]

STDs don't generally cause sore throat, whereas hundreds of other, nonsexually acquired viruses do it all the time.  Therefore, sore throat is almost never an STD symptom and does not indicate a need for STD testing.  So the answers are 1A) no and 1B) no.

I don't know where you were going with Q2, but I see no reason for you to be concerned about STD at this time.  You seem to have a pretty garden-variety, low risk sexual lifestyle, except that I suggest you start using condoms regularly for new partnerships, or even for ongoing partnerships if they are not committed and either of you might be having other partners.  Second, given that lifestyle, you should plan on routine STD testing once a year.  Otherwise, you won't need testing unless you get typical STD symptoms (i.e., not just sore throats).

Good luck--  HHH, MD