Keep it on, HIV+ people warned

Australian scientists have warned HIV-positive people to continue using condoms despite a report earlier this year that found people correctly using antiretroviral drugs could not transmit the virus to their partner during sex.

Four respected HIV researchers issued a statement on behalf of the Swiss Federal Commission for HIV/AIDS in January this year which found HIV-positive people with undetectable levels of virus in their blood and no other genital infections could not transmit the virus to their HIV-negative partners through sexual contact.

The report was criticised as it concentrated on heterosexual serodiscordant couples, not on male homosexual couples, where the risk of sexual transmission is higher.

In a special HIV/AIDS issue of the British medical journal The Lancet published today, Australian researchers led by Dr David Wilson and Professor David Cooper from the University of NSW's National Centre in HIV Epidemiology and Clinical Research (NCHECR) call into question the conclusions of the Swiss experts and fear infection could potentially quadruple in certain populations if HIV-positive people follow the Swiss advice.

Wilson's team used mathematical modelling to analyse the implications of the Swiss statement, finding that over a prolonged period, particularly among serodiscordant homosexual partners, the cumulative possibility of transmission is as high as four-fold.

The researchers accept that the risk of transmission in heterosexual partnerships in the presence of effective treatment is very low, but warn it is not zero. They also note that the transmission risk in male homosexual partnerships, over a prolonged period of repeated exposures, is much higher.

"While it is true that the individual risk of HIV transmission per act is fairly small for people on retrovirals, the risk of transmission over large numbers of acts could be substantial," Wilson said.

Dr Jonathan Anderson, president of the Australasian Society for HIV Medicine, who is also based at the NCHECR, said that while the viral load goes down in the blood due to antiretrovirals, that may not be the case in semen or in vaginal and anal fluids.

"This may be confusing," Anderson said. "Antiretrovirals can complement consistent condom use but replacing condom use with medications may end in disaster."

The researchers write that if the Swiss claim of non-infectiousness in effectively treated patients was widely accepted, and condom use subsequently declined, there was the potential for substantial increases in HIV incidence.

Also in special issue of The Lancet today, Canadian researchers have found that improvements in and long-term effectiveness of combination antiretroviral therapy (cART) for HIV-positive patients have seen life expectancy increase by some 13 years since cART was introduced in 1996.

The same period saw an accompanying drop in mortality of nearly 40 per cent. The figures, however, only relate to patients in high income countries in Europe and North America.

Despite the positive results, however, an HIV-positive person starting cART at age 20 will live on average to age 63, 20 years less than an HIV-negative person of the same age.