1. Department of Medicine, University of Ngaoundere, Garoua, Cameroon
2. Department of Internal Medicine and Specialties, University of Yaounde I, Yaoundé, Cameroon
3. Department of Pneumology, Jamot Yaounde Hospital, Yaounde, Cameroon
4. Department of Medicine, Higher Institute of Medical Technology, Baptist Hospital of Maroua, Maroua, Cameroon
5. Department of Medicine, Higher Institute of Medical Technology, Centre des Urgences de Yaounde, Cameroon
6. Department of Medicine, Higher Institute of Medical Technology, Polymer Polyclinic, Yaounde, Cameroon,