1. Ethiopian-Netherlands AIDS Research Project (ENARP) at the Ethiopian Health and Nutrition Research Institute (EHNRI), Addis Ababa, Ethiopia.
2. Department of Human Retrovirology, Academic Medical Center, University of Amsterdam, 1105 AZ, Amsterdam, The Netherlands.
3. Division of Public Health and Environment, Municipal Health Service, 1000 CE, Amsterdam, The Netherlands.
4. National Referral Laboratory for AIDS, EHNRI, Addis Ababa, Ethiopia.
5. Ethiopian Red Cross Society-National Blood Transfusion Service, Addis Ababa, Ethiopia.
6. AIDS/STD Control Team, Ministry of Health, Addis Ababa, Ethiopia.