1. U.S. Military HIV Research Program/Division of Retrovirology, Walter Reed Army Institute of Research, Rockville Maryland 20850.
2. U.S. Naval Medical Research Unit 3, Cairo, Egypt.
3. National HIV/AIDS Control Program, Ministry of Public Health, Islamic Republic of Afghanistan, Kabul, Afghanistan.
4. Division of International Health and Cross-Cultural Medicine, University of California, San Diego, La Jolla, California 92073.