1. Department of Global Health and Development, London School of Hygiene & Tropical Medicine , 15-17 Tavistock Place, London WC1H 9SH, UK
2. Heidelberg Institute of Global Health, University Hospital and Medical Faculty, Heidelberg University , Im Neuenheimer Feld 130.3, Heidelberg 69120, Germany
3. MRC Unit The Gambia at the London School of Hygiene & Tropical Medicine , Atlantic Boulevard, Fajara, PO Box 273, Banjul, The Gambia
4. Institut de Recherche en Santé, de Surveillance Epidémiologique et de Formation , 4 Rue 2 D1 Pole Urbain de Diamniado BP 7325, Dakar, Sénégal
5. Institut Supérieur des Sciences de la Santé, Université Nazi Boni , 01 BP 1091, Bobo-Dioulasso, Burkina Faso
6. Université Cheikh Anta Diop , Fann Campus, Dakar BP 5005, Sénégal