In addition to sexually transmitted infections (STIs), unprotected sex can have other health risks for HIV-positive people. There have been about 30 reported cases where a person with HIV has been reinfected, or superinfected, with another subtype or strain of HIV that is resistant to anti-HIV drugs.
In some cases this has resulted in the person's HIV viral load increasing and CD4 cell count falling. In addition, their treatment options have been limited because the type of HIV they were reinfected with was resistant to some or all of the anti-HIV drugs they were taking as well as others they had never taken.
Superinfection has been reported in both gay men and heterosexual people.
Although reinfection appears to be rare, there seem to be some factors that might increase the risk of it happening. Many of the cases occurred soon after a person was first infected with HIV, and often when people were taking a break from HIV treatment. There has also been a case of reinfection reported involving a man who had had HIV for many years. He already had resistance to most of the available anti-HIV drugs and had unprotected sex with lots of men. Furthermore, there has been a single case of superinfection involving someone who was taking HIV treatment.