Warning: The following contains the use of the word "penis" by a conservative columnist.

Circumcision is an, ahem, uncomfortable topic. The traditional Jewish bris calls this medical procedure a sign of blessing on the newcomer. Ten out of 10 male infants seem to disagree.

During World War II, American soldiers were often circumcised to prevent the spread of sexually transmitted diseases (STDs) -- another hidden sacrifice of the Greatest Generation. From the 1950s to the mid-1970s, the circumcision of American newborn boys became increasingly common. Then a minor backlash set in, and circumcision rates declined for a time. Today the American Academy of Pediatrics takes a neutral stance, leaving the decision up to parents.

But suddenly Uncle Irving seems pretty wise. Studies in Uganda, Kenya and South Africa indicate circumcision halves the risk of adult males contracting HIV through heterosexual intercourse. An author of one of those studies, Robert Bailey of the University of Illinois at Chicago, told me, "There is nothing else currently out there in public health or HIV prevention with protection results this compelling." Studies are ongoing to see if male circumcision protects women from transmission -- researchers suspect it might but are waiting for the evidence. The benefit for men, however, is increasingly undeniable.

Why does circumcision help prevent AIDS? The foreskin of the penis -- the part removed in circumcision -- has a high concentration of cells that bring HIV into the body. A circumcised male is exposed to less HIV virus during sexual relations, and has less chance of being infected.

This helps explain one of the great mysteries of HIV in Africa: why infection rates vary so widely across the continent. The most mind-numbing levels of infection -- sometimes upward of 30 percent -- are concentrated in regions of southern Africa where most men are uncircumcised. Massive infection rates seem to be associated with uncircumcised males, ulcerative STDs and having many concurrent sexual partners. Researchers hope that broader circumcision will remove a contributor to this deadly cycle.

As you'd expect, there are cultural obstacles to broader circumcision in Africa. Circumcision, or the lack of it, can be a matter of cultural identity, distinguishing Christians from Muslims (who, like Jews, are traditionally circumcised), and even dividing ethnic groups within a country. But surveys in Africa indicate an openness to the procedure among uncircumcised Christians. One researcher, Maria Wawer of Johns Hopkins University, says, "A response we got was, 'Well, what's the big deal? Jesus was circumcised.' "

There are also practical obstacles. Like any operation, circumcision presents a risk of infection. Much of Africa lacks the equipment and personnel to perform the procedure on a large scale. But similar arguments were made against the possibility of AIDS treatment. A concerted American and international commitment proved that pessimism to be unjustified. Continued...