Nairobi — Circumcision, which three years ago was shown to protect men from contracting HIV by as much as 60 per cent, has no such benefit for their sex partners, a new study conducted in Uganda has established.

The study involved 922 uncircumcised HIV-positive men aged between 15 and 49 years.

Half of the men were circumcised immediately and the other half left uncut to serve as the control group.

All the men were counselled not to have unprotected sex with their partners, who were nevertheless enrolled to establish how many in each group would get infected.

In total, 90 female partners of the newly circumcised group was enrolled, as were 70 of the control group made up of uncircumcised men.

The women were tracked for two years and tested for HIV to establish infection rates.

The study was carried out in Rakai, Uganda, which has long been considered Ground Zero of the HIV/Aids epidemic in the region.

At the end of the study, 18 per cent of the women in the circumcised group were found to be infected with HIV, compared with 12 per cent in the control group.

This, lead researcher Maria Wawer from America's Johns Hopkins Bloomberg School of Public Health says, shows that male circumcision does not directly protect women partners from contracting the virus.

The results of the study were released at a conference on retroviruses and opportunistic infections held in Boston, USA.

Following the study's key finding, it was stopped early as there was no probability that the data obtained would change.

Circumcision could, however, have a protective effect on women by reducing the prevalence rates in men, Dr Wawer said.

According to Dr Wawer and her colleagues, the fact that most of the infection in the circumcised group occurred within six months of circumcision may be explained by the possibility that some of the men had intercourse without giving time for the circumcision wound to heal properly, thus exposing their partners to HIV-infected blood.

"The possibility of higher risk of transmission in couples who resumed intercourse before complete wound healing cannot be excluded," Dr Wawer said in her report.

The latest findings differ markedly from those obtained in a human papillomavirus study in 2002, which established that circumcised men were less likely to spread the infection than uncircumcised men.

In 2006, studies in Uganda, Kenya and South Africa showed that removal of the foreskin could lower the risk of HIV infection in uninfected men by around 60 per cent.

The minor surgical procedure has since been recommended as a preventive measure, together with the traditional ABC (Abstinence, Being faithful to one partner and use of Condoms).

Aids experts say that circumcision probably lowers infection risk by getting rid of the foreskin, which is rich in special immune cells known as Langerhans, to which HIV is attracted.

Circumcision also ensures that infected fluids are not retained for long.