Ron H Behrens1, Christoph Hatz2, Leo Visser3. 1. Department of Clinical Research, Faculty of Tropical Medicine and Infectious Diseases, London School of Hygiene and Tropical Medicine, London, UK. 2. Department of Medicine and Diagnostics, Swiss Tropical and Public Health Institute, Basel, Switzerland. 3. Department of Infectious Diseases, Leiden University Medical Center, Leiden, The Netherlands.