1. Institute of Public Health, College of Medicine and Health Sciences, University of Gondar, P.O. BOX 196, Gondar, Ethiopia
2. School of Biomedical and Laboratory Sciences, College of Medicine and Health Sciences, University of Gondar, P.O. BOX 196, Gondar, Ethiopia
3. School of Medicine, College of Medicine and Health Sciences, University of Gondar, P.O. BOX 196, Gondar, Ethiopia