1. Department of Public Health, Faculty of Health Sciences, Walter Sisulu University, Private Bag X1, Mthatha 5117, South Africa
2. College of Graduate Studies, University of South Africa, Johannesburg 0001, South Africa
3. Department of Laboratory Medicine and Pathology, Faculty of Health Sciences and National Health Laboratory Services (NHLS), Walter Sisulu University, Private Bag X1, Mthatha 5117, South Africa