Male circumcision

There is strong biological and epidemiological evidence that circumcised men are less vulnerable to HIV infection via heterosexual intercourse than uncircumcised men.

Circumcision is believed to reduce the risk of male infection because it removes the vulnerable tissue inside the foreskin, which contains Langerhans cells (a type of cell particularly vulnerable to HIV infection). The mucosa that covers the inside of the foreskin contains more Langerhans cells than almost any other part of the body except the gut. These are a type of dendritic cell whose job is to ferry foreign particles to the lymph nodes for recognition by the immune system, and which HIV hijacks as part of its infection strategy. In ex-vivo explant models, foreskin mucosa was found to be nine times more vulnerable to HIV infection than cervical tissue.

The area under the foreskin is also vulnerable to trauma, and is more likely to become abraded if sufficient lubrication is not present. Also, uncircumcised men may be more vulnerable to sexually transmitted infections (STIs), because the area under the foreskin can retain bacteria acquired during sex, thus increasing the chance that an infection will become established.

In Africa, the countries where less than 20% of the male population is circumcised form a broad swathe extending from the Central African Republic and southern Sudan in the north, through the former British colonies of east Africa, and down to Botswana, Zimbabwe and Swaziland.¹ The only country that has high (>10%) levels of HIV prevalence but also higher circumcision levels than 20% is South Africa, whose very mixed cultural, sexual and racial background may make it a special case.