THURSDAY, Jan. 12, 2012 (HealthDay News) -- The level of the HIV-1 virus in the blood of an HIV-infected person is the single most important risk factor for sexual transmission of HIV to an uninfected partner, a new study of heterosexual couples has found.
The research, published online Jan. 12 in The Journal of Infectious Diseases, also confirmed that the use of condoms significantly reduces the risk of transmission of HIV, the virus that causes AIDS.
Researchers studied nearly 3,300 HIV-discordant couples (one partner has HIV and the other is HIV-free) in sub-Saharan Africa and found that the average rate of HIV-1 transmission was about one per 900 acts of sexual intercourse.
The level of HIV-1 RNA in the blood of the infected partner was the most important factor in HIV transmission. The higher the viral load in the infected partner, the higher the risk of transmission. This finding highlights the importance of lowering viral load in order to reduce the spread of HIV-1 through sex, the researchers said in a news release from the Infectious Diseases Society of America.
The investigators also found that older age was associated with a reduced rate of HIV transmission and that male circumcision reduced female-to-male transmission by about 47 percent. However, genital herpes infections and genital ulcers were associated with increased transmission rates.
Condom use reduced the risk of HIV transmission by 78 percent, according to James Hughes of the University of Washington in Seattle and colleagues there and in Africa.
"Our results underscore the importance of antiretroviral therapy and, possibly, treatment of co-infections, to reduce plasma HIV-1 viral load in HIV-1 infected partners, and condom promotion, male circumcision, and treatment of symptomatic sexually transmitted infections for HIV-1 uninfected partners as potential interventions to reduce HIV-1 transmission," the researchers concluded in their report.
The U.S. Centers for Disease Control and Prevention has more about HIV transmission.