I have been poz for 3 yrs and on meds the whole time. I have an undetectable viral load and high CD-4's. I never miss a dose of my meds. I am with a neg partner. He likes to have unprotected anal sex (insertive and receptive) with me without ejaculation into him on my part. We know there is some risk involved with this but are comfortable with it. I know there are small amounts of HIV in my semen even with an undetectable VL in my bloodstream. Are there any hard statistics on transmission risks in this situation, with undetectable viral load and no ejaculation into the neg partner? Is there really enough HIV in my pre-ejaculate/semen to put him at a great risk for infection, or can we be reasonably sure that there is an acceptable low risk of infection?

Hello,

Your facts are correct:

1. There is risk involved in magnetic couples having unprotected anal sex, even with an undetectable viral load.

2. Yes, your semen may have a different viral load (VL) than the VL measured in your blood.

Now to your questions:

1. No, there are no hard statistics on your particular situation, because there are too many variables to control for. Also, because we know this type of exposure does carry some degree of risk, it would be unethical to conduct a clinical trial to determine exactly how risky. We can say the risk is real.

2. Can you be reasonably sure there is an acceptable low risk of infection? Although ultimately that would depend on how you define "acceptable low risk," the general answer to your question is no.

Your basic premise that an undetectable plasma viral load decreases the risk of HIV transmission is true. In addition, pulling out before ejaculating also decreased the overall risk of transmission. The important question, however, is that taking these "harm reduction" measures into account, is unprotected anal sex safe enough? Based on our current knowledge, the answer would have to be no.

If despite this information, you and your partner remain comfortable with the risks associated with unprotected anal sex, I would suggest you consider enrolling in a PrEP study. These are clinical trials designed to investigate where pre-exposure prophylaxis (PrEP) is effective in reducing the risk of HIV transmission. You can read about these clinical trials in the archives. They involve the negative partner taking Truvada (Viread plus Emtriva) on a chronic basis. I must emphasize we do not know if this is an effective strategy or not. However, it may afford your negative partner some degree of protection.

Good luck.

Dr. Bob