1. The Johns Hopkins University School of Public Health, Baltimore, Maryland; Epidemiology and Health Services Research Unit, Mexican Institute of Social Security, and Center for Population Health Research, National Institute of Public Health of Cuernavaca, Morelos, Mexico.
2. Center for Population Health Research, National Institute of Public Health of Cuernavaca, Morelos, Mexico.
3. The Johns Hopkins University School of Public Health, Baltimore, Maryland and Epidemiology and Health Services Research Unit, Mexican Institute of Social Security, Cuernavaca, Morelos, Mexico.
4. The Johns Hopkins University School of Public Health, Baltimore, Maryland and Epidemiology and Health Services Research Unit, Mexican Institute of Social Security, Cuernavaca, Morelos, Mexico.
5. The Johns Hopkins University School of Public Health, Baltimore, Maryland.
6. Digene Corporation, Gaithersburg, Maryland.
7. Medical College of Georgia, Augusta, Georgia.
8. Nutritional Epidemiology Research Unit, Mexican Institute of Social Security, Mexico DF, Mexico.
9. Epidemiology and Health Services Research Unit, Mexican Institute of Social Security, Cuernavaca, Morelos, Mexico.