1. Internal Medicine Department, Douala General Hospital, Douala, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, Douala, Environmental and Lung Health Association, Douala
2. Faculty of Health Sciences, University of Buea, Buea
3. Faculty of Medicine and Pharmaceutical Sciences, University of Douala, Douala, Jamot Hospital, Yaounde
4. Faculty of Health Sciences, University of Buea, Buea, Hôpital Laquintinie, Douala, Cameroon
5. Hôpital Laquintinie, Douala, Cameroon
6. Internal Medicine Department, Douala General Hospital, Douala, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, Douala
7. Faculty of Medicine and Pharmaceutical Sciences, University of Douala, Douala