1. Department of Public Health, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
2. Division of Surveillance, Center longstafor Disease Control, Department of Health, Taipei, Taiwan.
3. School of Public Health, National Defense Medical Center, National Defense University, Taipei, Taiwan.
4. Division of HIV/AIDS Prevention and Control, Center longstafor Disease Control, Department of Health, Taipei, Taiwan.