1. National Institute for Communicable Diseases, Division of the National Health Laboratory Service , Johannesburg , South Africa
2. Right to Care , Pretoria , South Africa
3. Centre for the AIDS Programme of Research in South Africa , Durban , South Africa
4. Department of Epidemiology, Mailman School of Public Health, Columbia University , New York, New York , USA
5. National Department of Health , Pretoria , South Africa
6. Council for Scientific and Industrial Research , Pretoria , South Africa
7. School of Public Health, Faculty of Health Sciences, University of Witwatersrand , Johannesburg , South Africa
8. School of Pathology, Faculty of Health Sciences, University of the Witwatersrand , Johannesburg , South Africa
9. Department of Human Nutrition and Dietetics, Faculty of Health Sciences, University of Pretoria , Pretoria , South Africa
10. Clinical HIV Research Unit, Department of Internal Medicine, Faculty of Health Sciences, University of the Witwatersrand , Johannesburg , South Africa