1. AIDS Program, Section of Infectious Diseases, Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut, USA
2. Institute for Community Research, Hartford, Connecticut, USA
3. Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut, USA
4. Centre of Excellence for Research in AIDS, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia