1. University of Zambia, Lusaka, Zambia
2. Kinshasa School of Public Health, Kinshasa, Democratic Republic of the Congo
3. Research Triangle Institute, Research Triangle Park, North Carolina, USA
4. National Institute of Child Health and Human Development, Rockville, Maryland, USA
5. National Cancer Institute, Rockville, Maryland, USA
6. Drexel University College of Medicine, Philadelphia, Pennsylvania, USA