1. Department of Public Health, Faculty of Medicine and Biomedical Sciences University of Yaoundé 1 Yaoundé Cameroon
2. Department of Disease, Epidemics and Pandemics Control, Ministry of Public Health Yaoundé Cameroon
3. Department of Medicine University of Cape Town and Groote Schuur Hospital Cape Town South Africa
4. Department of Epidemiology and Public Health Centre Pasteur of Cameroon Yaoundé Cameroon
5. School of Public Health, Faculty of Medicine University of Paris Sud XI Le Kremlin Bicêtre France