1. Department of Hematology and Blood Transfusion, Aminu Kano Teaching Hospital, Kano, Nigeria
2. College of Health Sciences, Bayero University Kano, Kano, Nigeria
3. Department of Ophthalmology, Aminu Kano Teaching Hospital, Kano, Nigeria
4. Department of Hematology, Murtala Mohammed Specialist Hospital, Kano, Nigeria
5. Department of Chemical Pathology, Aminu Kano Teaching Hospital, Kano, Nigeria
6. Department of Epidemiology, University of Alabama at Birmingham, School of Public Health, Birmingham, AL, USA