1. Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002 Basel, Switzerland
2. University of Basel, P.O. Box CH-4003, Basel, Switzerland
3. Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
4. Institute of Infectious Diseases and Molecular Medicine, University of Cape Town, Rondebosch 7701, South Africa
5. South African Medical Research Council Drug Discovery Unit, University of Cape Town, Rondebosch 7701, South Africa