Squealing with delight, young Elvis rushes off to greet his mother as she wends her way towards the family's hut in north-eastern Botswana's Dukwi refugee camp. The Zimbabwean infant, aged almost three, is a picture of health. But one year ago, carrying the Human Immunodeficiency Virus (HIV), he was near death's door. Elvis could barely sit up. His body was wracked with opportunistic infections, including tuberculosis, and he was constantly in hospital for treatment.