1. University of Zambia School of Medicine, PO Box 39520, Lusaka, Zambia
2. University of Nebraska Virology Centre, USA
3. CDC, Zambia
4. University of Zambia School of Medicine, PO Box 39520, Lusaka
5. University Teaching Hospital, Lusaka
6. Data Entry Operation, University of Zambia School of Medicine, PO Box 39520, Lusaka, Zambia