1. Disease Control and Elimination Theme, Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, Fajara, The Gambia
2. Microbiological Diagnostic Unit Public Health Laboratory, Department of Microbiology and Immunology, University of Melbourne, Doherty Institute for Infection and Immunity, Victoria, Australia
3. Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK