1. Department of Paediatrics and Child Health; Red Cross War Memorial Children's Hospital; University of Cape Town; South Africa
2. Medical Research Council (MRC) Unit on Child and Adolescent Health; Cape Town South Africa
3. Division of Epidemiology and Biostatistics; School of Public Health and Family Medicine; University of Cape Town; South Africa
4. Department of Psychiatry and Mental Health; University of Cape Town; South Africa
5. Medical Research Council (MRC) Unit on Anxiety and Stress Disorders; Cape Town South Africa