Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, the Netherlands.|Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, the Netherlands.|Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, the Netherlands.|Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, the Netherlands.|Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, the Netherlands.|Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, the Netherlands.|Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, the Netherlands.|Leiden University Medical Center, Department of Medical Microbiology, Leiden, the Netherlands.|Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, the Netherlands.