QUESTION
I'm currently talking to a guy and there's definitely the possibility of a relationship. The thing is, he's HIV+ and I'm HIV-. If this relationship progresses and becomes intimate, I would be the top and he would be the bottom. Now I know if we use a condom properly every time that I'm at very low risk of getting HIV from my partner. I'm wondering, though, if his viral load was to increase, do I need to be more concerned about transmission? Or am I safe as long as I continue to use condoms?

ANSWER
There is some risk, albeit it small, from topping a man known to be HIV positive, even if you use a condom. The risk is estimated at about 1 in 2,500 - a low risk but not zero. Without using a condom, the per-contact risk for tops with an HIV-positive partner increases in 1 in 1,666.

A high viral load or the presence of an STD (for either partner) increases the amount of virus and/or cells that can get infected, consequently increasing risk of HIV transmission. Even if your potential partner has a low viral load, it only reflects the level of HIV in his blood. The level of HIV in his genital tract where semen is produced can be much higher, particularly if there is an STD (STDs have been proven to increase production of HIV). A recent study has also shown that the amount of HIV in the rectum can be greater than the amount in the blood, even in those people who are on effective medications.

For this reason, a full STD checkup -- including rectal screening for chlamydia and gonorrhea, throat screening for gonorrhea and blood testing for syphilis and herpes -- may be in order for both of you. In general, you can take charge of your health by getting regular STD check-ups, and using lots of lube and condoms every time you have anal sex. You're doing a great job by thinking about this and doing the research before you start a relationship. Communication with this new man about your preferences and fears will serve you well in friendship, love, and satisfying safer sex.

To your health,
Dr. K