1 Department of Internal Medicine & Infectious Diseases, Amsterdam University Medical Centers, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
2 Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand.
3 Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford OX3 7LG, UK.