1. Department of Disease Control, London School of Hygiene & Tropical Medicine, Keppel Street, London, WC1E 7HT England.
2. Institute of Public Health, Ruprecht-Karls-University, Heidelberg, Germany.
3. Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania.
4. Bill and Melinda Gates Foundation, Seattle, United States of America.
5. Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, England.