[1] University of the West Indies,Department of Basic Medical Sciences, Faculty of Medical Sciences
[2] University of the West Indies,Department of Community Health & Psychiatry
[3] University of the West Indies,Epidemiology Research Unit, Tropical Medicine Research Institute
[4] University of Pittsburgh,Department of Epidemiology and Division of Cancer Prevention and Population Science
[5] University of the West Indies,Department of Microbiology
[6] University of the West Indies,Department of Obstetrics and Gynaecology
[7] State University of New York,Department of Epidemiology and Biostatistics, Downstate School of Public Health