1. Bernhard Nocht Institute for Tropical Medicine, 20359 Hamburg, Germany
2. Faculty of Mathematics, Informatics and Natural Sciences, University of Hamburg, 20146 Hamburg, Germany
3. Department of Virology, Medicum, University of Helsinki, 00100 Helsinki, Finland
4. Department of Veterinary Biosciences, University of Helsinki, 00100 Helsinki, Finland
5. Department of Geosciences and Geography, University of Helsinki, 00100 Helsinki, Finland
6. Finnish Meteorological Institute, 00101 Helsinki, Finland
7. Unit of Microbiology, Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, 40138 Bologna, Italy
8. Virology and Immunology, Diagnostic Center, Helsinki University Hospital (HUSLAB), 00290 Helsinki, Finland