*Warning - Contains Sexual ContentHIV/AIDS AND ORAL SEX
The likelihood of transmission of HIV from an infected person to an uninfected person varies significan'tly depending on the type of exposure or contact involved. The risk of becoming infected with HIV through unprotected (without a condom) oral sex is lower than that of unprotected anal or vaginal sex. However, even a lower risk activity can become an important way people get infected if it is done often enough. The Options Project found that 7.8% (8 of 102) of recently infected men who have sex with men in San Francisco were probably infected through oral sex. Most of these men believed that the risk was minimal or non-existent.
"Going down" on an HIV positive man or woman can be risky even if the likelihood of becoming infected is small. Though most studies suggest that oral sex transmission is lower than vaginal or anal sex transmission, getting semen or vaginal fluids in the membrane of the mouth increases the chance of infection. Other factors that may come into play regarding HIV infection and oral sex include: viral load, condition of oral health and immune response.
Source: Center for Disease Control