1. Epidemiology and Surveillance Unit, Centre for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands
2. Epidemiology Unit, KIT (Royal Tropical Institute) Health, Amsterdam, the Netherlands
3. Office of the Chief Scientist, European Centre for Disease Prevention and Control (ECDC), Stockholm, Sweden
4. Surveillance and Response Support Unit, European Centre for Disease Prevention and Control (ECDC), Stockholm, Sweden (affiliation when the work was performed)
5. Institute of Tropical Medicine, Antwerp, Belgium (current affiliation)