According to the study most people infected with HIV are also infected with herpes which is frequently reactivated and associated with increased levels of HIV. This suggested that treating herpes could reduce the risk of HIV infection.

The study involved 3 408 couples from 14 sites in Africa. Patients infected with both HIV and herpes and had CD4 counts (which measures their level of immunity)- of 250 were given a standard 400mg dose of acyclovir for up to two years while the control group was given  a placebo (substances that are prescribed like drugs, but are made up of inactive chemicals such as starch or sugar).

Despite a significant decrease in the concentration of HIV and genital ulcer disease, the drug did not reduce the risk of HIV transmission to uninfected partners, according to the study.

Researchers said the lack of efficacy of the acyclovir did not appear to have been caused by poor activity of acyclovir against herpes or poor adherence to treatment as assessed by monthly pill counts and by serum acyclovir testing in a subgroup of participants.

The authors said that most transmissions of HIV infection in Africa were thought to occur within stable, cohabiting HIV serodiscordant couples.

‘€œApproximately 30% of HIV-1 transmissions in this cohort of stable, cohabiting couples were attributable to outside partnerships. Couples in which one of the partners is seropositive and the other is seronegative for HIV-1 should be counselled on potential misconceptions about the risk from sexual activity with other partners whose HIV status is unknown,’€ said the researchers.

They said it was likely that the lower rate of HIV infections that occurred during their study   was due to having provided counselling on risk reduction, free condoms and other preventative services.

They suggested that new strategies to reduce the risk of HIV infection for HIV serodiscordant couples were needed.

For full report click on: http://content.nejm.org/cgi/content/full/362/5/427