1. Department of Medical Sciences, Ministry of Public Health, Nonthaburi, 11000 Thailand
2. Centers for Disease Control and Prevention, Atlanta, Georgia 30333
3. Centers for Disease Control and Prevention, Atlanta, Georgia 30333; HIV/AIDS Collaboration, Nonthaburi, 11000 Thailand
4. University College London, Medical School, London WC1E 6BT, UK
5. Aaron Diamond AIDS Research Center, Rockefeller University, New York, New York 10016
6. HIV/AIDS Collaboration, Nonthaburi, 11000 Thailand
7. Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700 Thailand