After receiving their diagnosis, people in the acute phase of HIV infection are quick to adopt behaviors that will help protect others from the virus, according to findings of a study presented at the 2007 National HIV Prevention Conference in Atlanta.

Experts at the U.S. Centers for Disease Control and Prevention (CDC) and other institutions suggest that risk of sexual HIV transmission is high when the HIV-positive partner is going through the early “acute” phase of HIV infection. During the first several weeks of infection, viral load in both blood and genital fluids often reaches very high levels, rendering the person highly infectious. What’s more, many people in the initial throes of HIV disease are not aware that they are infected with the virus.

Wayne Steward, PhD, of the Center for AIDS Prevention Studies at the University of California, San Francisco, and his colleagues sought to determine whether identification of HIV-positive people during the acute stage of infection would lead them to change their sex behaviors in a manner that would protect others from becoming infected.

Steward’s team identified 15 people with acute infection, 13 of whom were men who have sex with men (MSM). The researchers collected surveys of the participants’ sex behavior both before and after receiving an HIV diagnosis. In the two months before diagnosis, participants reported that 23 percent of the unprotected anal or vaginal sex they engaged in was with partners who were believed to be HIV positive. The majority of unprotected sex was with partners who were believed to be HIV negative or whose status was unknown.

In the two months following their diagnoses, the selection of partners for unprotected sex changed substantially. Participants reported that 97 percent of their unprotected sex acts occurred with partners who were HIV positive. Moreover, the study participants expressed a strong preference for having sex only with others who were HIV positive. Also, the total number of unprotected sex acts among the 15 study participants decreased after diagnosis, with 264 unprotected sex acts reported before diagnosis and 170 unprotected sex acts reported after diagnosis.

Although Steward conceded that the study was small, his team nevertheless concluded that it suggests that efforts to identify and counsel people in the acute phase of HIV infection could result in substantial reductions in risk behavior.