1. Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
2. Centre for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada
3. Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
4. Biomedical Research and Training Institute, Harare, Zimbabwe
5. Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
6. University of Zimbabwe, Harare, Zimbabwe