Siphiwe Tfumbatsi, 35, and Themba Matabela, a gardener, live outside of Mbabane. Siphiwe learned she was HIV positive when their two-year-old, Tenele, was diagnosed as an infant. Tenele started treatment when she was one, and Khaya, 4, began during Larry Towell’s first visit. "Since they got that treatment," Themba says, "we didn’t go to hospital, neither of them has been sick." Although she still shows no symptoms of AIDS, Siphiwe began treatment a few months earlier while pregnant, to reduce the risk of transmission to her baby. The baby girl was born in January 2008 and has so far tested negative...