1. Red Cross Blood Bank Foundation, Willemstad, Curaçao.
2. Stichting HIV Monitoring (SHM), Amsterdam, The Netherlands.
3. Department of Epidemiology and Biostatistics, VU University Medical Center, Amsterdam, The Netherlands.
4. St. Elisabeth Hospital, Willemstad, Curaçao.
5. Epidemiology and Research Unit, Medical and Public Health Service of Curaçao, Willemstad, Curaçao, The Netherlands Antilles.
6. Department of Infectious Disease Epidemiology, Medical Faculty of Imperial College, London, United Kingdom.