In a soft, faltering voice, her large brown eyes staring absently ahead, Winfrida Besa repeats "A-B-C-D" over and over as she tries to sing the ABCs. With her thin, hollow face and slight frame, 7-year-old Winfrida looks much younger than she really is.

"Winfrida doesn't go to school. She would just leave the classroom and wander off, and we worry she would get lost," sighs her grandfather, Bobby Besa, 60. The little girl was born "normal," he says, but soon she was exhibiting a constellation of disturbing symptoms that are familiar to residents of Kabwe, Zambia. The diagnosis came after blood testing at the local clinic: Lead poisoning.