1. World Health Organization, avenue Appia 20, 1211 Geneva 27, Switzerland.
2. Joint United Nations Programme on HIV/AIDS, Geneva, Switzerland.
3. American University of Beirut, Beirut, Lebanon.
4. Liverpool School of Tropical Medicine, Liverpool, England.
5. London School of Hygiene & Tropical Medicine, London, England.
6. Burnet Institute, Melbourne, Australia.
7. CAPRISA, University of KwaZulu-Natal, Durban, South Africa.