1. Infectious Diseases, Center for Tropical Medicine & Travel Medicine, Division of Internal Medicine, AIGHD, Academic Medical Center, University of Amsterdam, Meibergdreef 9, PO Box 22660, 1100 DD Amsterdam, The Netherlands
2. Department of economics, VU University Medical Center, Amsterdam, The Netherlands
3. Barcelona Centre for International Health Research (CRESIB), Hospital Clínic-Universitat de Barcelona, Barcelona, Spain