1 Division of Infectious Diseases and Hospital Epidemiology, University Hospital Basel, CH-4031 Basel, Switzerland.
2 Bernard-Nocht Institute for Tropical Medicine and WHO Collaborating Centre for Arbovirus and Haemorrhagic Fever Reference and Research National Reference Centre for Tropical Infectious Diseases, Hamburg, Germany.
3 Bernard-Nocht Institute for Tropical Medicine and WHO Collaborating Centre for Arbovirus and Haemorrhagic Fever Reference and Research National Reference Centre for Tropical Infectious Diseases, Hamburg, Germany; German Centre for Infection Research, Hamburg-Lübeck-Borstel, Hamburg, Germany.
4 Division of Infectious Diseases and Hospital Epidemiology, University Hospital Basel, CH-4031 Basel, Switzerland. Electronic address: manuel.battegay@usb.ch.