1. Infectious Diseases Epidemiology Unit, School of Public Health & Family Medicine, University of Cape Town, Cape Town, South Africa.
2. Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, New York.
3. MRC Unit on Anxiety and Stress Disorders, University of Stellenbosch, Cape Town, South Africa.
4. Department of Psychiatry, University of Cape Town, Cape Town, South Africa.