1. Faculty of Medicine and Pharmaceutical Sciences, University of Douala, Douala, Cameroon;
2. Department of Internal Medicine, Douala General Hospital, Douala, Cameroon;
3. Faculty of Medicine and Biomedical Sciences, University of Yaoundé I, Douala, Cameroon;
4. Department of Internal Medicine, Douala Laquintinie Hospital, Douala, Cameroon;
5. Faculty of Medicine and Biomedical sciences, Yaoundé General Hospital Cameroon, Douala, Cameroon