1. Social Aspects of Health Programme, MRC/UVRI and LSHTM Uganda Research Unit, Entebbe, Uganda
2. Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, UK
3. MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK
4. Department of Global Health and Development, London School of Hygiene and Tropical Medicine, London, UK