1. U.S. Military HIV Research Program, Rockville, Maryland 20850.
2. Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland 21205.
3. Research Institute for Health Sciences, Chiang Mai University, Chiang Mai, Thailand.
4. Northern Drug Treatment Center, Chiang Mai, Thailand.
5. Walter Reed Army Institute of Research, Silver Spring, Maryland 20910.
6. Centers for Disease Control, Atlanta, Georgia 30333.