Prominent Ugandans have picked up this banner. The first lady, Janet Museveni, attempted to conduct a "virgin census" at the country's main university. One Ugandan parliamentarian proposed offering "chastity scholarships" to girls who could prove they had never had sex. Cultural notions of sex and morality are of course shaped by many forces; government policy is only one of them. Nonetheless, with more and more people living long lives with HIV, many from birth, a single-minded message of abstinence and morality seems not just counterproductive, but dangerous. Admitting that you carry a potentially deadly infectious disease and taking responsibility for containing it are hard enough; the near-certainty of censure by your friends and neighbors can make responsible action almost impossible.

It seems unrealistic to base policies on the expectation that asymptomatic HIV-positive youth will permanently abstain from sex, and foolish to drive them underground and away from the medication they've relied on since childhood. Today, the spread of resistant forms of the virus is still relatively rare in Africa, though it is said to be rising. And while resistance is limited, for the most part, to the most common anti retroviral regimens, the more expensive treatments available in other parts of the world are unaffordable to most Africans, so it's troubling to see the virus beginning to break through the first fire walls.

Before leaving Rose's home, I asked her how she was dealing with the rejection by those around her. "They can talk," she said. "It's up to them." The important thing was that she had learned her HIV-positive status and knew she had to take her drugs. "Tomorrow they could die," she said. "I will still be here. I know what I am, and I know what to do." In addition to infecting Peter and Beatrice, Rose had transmitted HIV to her youngest son. Half of her children carried the virus. As she spoke, Rose gazed at Beatrice's son, who was on a couch by the door, playing with Peter. For the baby, the prevention methods had worked. "Because I've tested myself and I've tested my children," Rose said, "I've managed to get a grandchild who is HIV-free," she said.