Male circumcision doesn’t reduce HIV transmission from men to women

In recent years the foreskin, the double fold of skin and mucous membrane that covers the head of the penis, has taken centre stage in the fight against HIV. It is rich in Langerhans cells and other immune cells that the virus can easily enter. Once infected, these cells not only act as reservoirs where the virus multiplies, but also carry it to nearby lymph nodes, where it spreads to other immune cells. Studies have shown that removing the foreskin can lower men's risk of HIV infection by 50 to 60%, and some have suggested that circumcision might also reduce transmission from men to women.

But a Ugandan study led by Dr Maria Wawer of the Johns Hopkins Bloomberg School of Public Health in Baltimore found that male circumcision did not protect the men's female partners. The study included 922 uncircumcised men with HIV aged 15 to 49, randomly assigned to be circumcised or not. Their uninfected female partners also took part, 90 in the circumcised group and 70 in the uncircumcised group, and were tested for the virus after 6, 12 and 24 months. All participants were taught how to prevent HIV and given free condoms.

After two years, 18% of the women in the circumcised group had been infected with HIV, compared with 12% in the uncircumcised group. The cumulative probability of infection at 24 months was 22% among women in the circumcised group and 13% in the uncircumcised group. Most infections in the circumcised group happened within six months of the operation: the researchers said some men had sex before their wounds healed, exposing their partners to blood containing HIV.

In an accompanying editorial, Dr Jared Baeten of the University of Washington in Seattle and colleagues stressed the importance of circumcision programmes for men at risk of HIV, but called for more attention to couples in which one partner is infected and the other isn't. Services to prevent transmission in these couples, including couples testing, help with disclosing HIV status and ongoing counselling, should be a public health priority and should be built into male circumcision programmes, to give uninfected women more protection.

About 33 million people worldwide live with HIV/AIDS, but the World Health Organization says male circumcision could greatly reduce the toll, preventing an estimated 5.7 million new infections and three million deaths over the next 20 years in sub-Saharan Africa alone.

The study was published on 18 July in The Lancet.