1. Department of Public and Global Health, Division of Infectious Diseases, World Health Organization Collaborating Centre for Traveller's Health, Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Zurich, Switzerland
2. Division of Epidemiology, Human Genetics and Environmental Sciences, University of Texas School of Public Health, Houston, TX, USA
3. Department of Global Health, Boston University School of Public Health, Boston, MA, USA
4. Section of Infectious Diseases, Department of Medicine, Boston Medical Center, Boston, MA, USA