New HIV Cases Could Quadruple Over 10 Years if Discordant Couples Discontinue Condom Use, Study Says
New HIV cases could quadruple over the next 10 years if couples in which one person is HIV-negative and the other is HIV-positive discontinue condom use based on factors such as suppressed viral loads, according to a study published Friday in the journal Lancet, Reuters reports (Tan, Reuters, 7/25).
For the study, David Wilson, an epidemiologist at the University of New South Wales, and colleagues used a mathematical model to estimate the risk of HIV transmission in discordant couples (AFP/Google.com, 7/24). The researchers based their calculations on 10,000 discordant couples each having 100 unprotected sexual encounters over 10 years.
The researchers found there would be an additional 215 female-to-male HIV transmissions, 425 male-to-female transmissions and 3,524 male-to-male transmissions if discordant couples became more complacent about condom use (Reuters, 7/25). The study found that an HIV-negative man would have a 0.22% annual risk of contracting HIV from an HIV-positive female partner, while an HIV-negative woman would have a 0.43% annual risk of contracting HIV from an HIV-positive male partner. HIV-negative men who have sex with men would have an annual 4.3% risk of contracting HIV from an HIV-positive partner, the study found (AFP/Google.com, 7/24). According to the researchers, the findings represent "an increase in incidence of four times compared with incidence under current rates of condom use" (Reuters, 7/25).
The study was conducted in response to a Swiss AIDS Commission statement released earlier this year that said HIV-positive people in discordant relationships who adhere to their treatment regimens, have suppressed viral loads and do not have other sexually transmitted infections likely would not transmit the virus through sexual contact. "If the Swiss commission's conclusions were adopted at a community level and resulted in reduced condom use, it would be likely to lead to substantial increases in infection," Wilson said.
Wilson added that although the "individual risk of HIV transmission per act is fairly small for people on antiretrovirals, the risk of transmission over large numbers of acts could be substantial." Jonathan Anderson, president of the Australasian Society for HIV Medicine, said that reduced HIV viral loads in blood -- the basis of the Swiss statement -- does not mean viral loads also are reduced in semen or vaginal and anal fluids (Medew, Age, 7/25).
If the Swiss "claim of non-infectiousness in effectively treated patients was widely accepted, and condom use subsequently declined, then there is the potential for substantial increases in HIV incidence," the study said (AFP/Google.com, 7/24). Anderson, who did not participate in the study, added that antiretrovirals "can complement consistent condom use, but replacing condom use with medications may end in disaster" (Reuters, 7/25).
An abstract of the study is available online.