Q: If you have sex with someone who is HIV infected, how likely are you to get the disease?
A: The typical statistic that gets quoted is that with every heterosexual contact with an HIV-infected person, the risk is 1 in 1,000. But that is only an estimate and recent data suggests that that it is inaccurate and is probably the lower bound. Today we think your chance of contracting HIV with a heterosexual contact could be as much as 1 in 3. There are many things that affect your chances. If a person has very advanced HIV disease and a high virus level in their system, there's a greater likelihood that they will transmit. If the partner who is HIV-negative has an STD, like herpes or gonorrhea, that makes her more vulnerable to acquiring HIV. All of those factors play into the risk of transmission. I would say the range is anywhere from 1 in 3 to 1 in 1,000.
Q: Do all condoms work in the prevention of HIV/AIDS?
A: You need to use a latex condom and need to have spermicide. It can't be one of those lambskin condoms or other biologic ones which are supposed to improve sensation but don't protect against HIV. The female condom is another way that women can protect themselves. It is more under a woman's control and less dependent on a man, although it certainly requires that he be a participant. There are other ways to protect yourself that are being investigated, things like microbicides (a gel that you insert in the vagina that would prevent HIV) or a diaphragm that has anti-HIV drugs in it. A lot of new methods are being studied. Our hope is that in the near future women will have many more options than just a condom to protect themselves.
Q: There is a perception that it is difficult for a woman to transmit HIV to a man. Is that true?
A: That is clearly a misperception. The reality is that it is easier for a man to transmit to a woman, just based on anatomy and the biology of penile-vaginal sex. It's a little less easy for a man to contract it from a woman due to the same anatomical issues. But I think what's important for people to recognize is that around the world, the man-to-woman ratio of HIV infection is basically one to one. So about half of the people in the world that are HIV infected are men and half are women, and the majority of the transmission that takes place outside the United States is through heterosexual transmission. That means men are getting it from women.