1. a The Africa Centre for Health and Population Studies , University of KwaZulu-Natal , Mtubatuba , South Africa
2. b Clinical Trials Unit, Medical Research Council , London , UK
3. c Educational Professional Practice Unit , University of Zululand , KwaDlangezwa , South Africa
4. d Department of Nursing Science , University of Zululand , KwaDlangezwa , South Africa
5. e Department of Infectious Disease Epidemiology , London School of Hygiene and Tropical Medicine , London , UK