1 Department of Neurology Leiden University Medical Center Leiden The Netherlands.
2 Department of Neurology Haga Teaching Hospital The Hague The Netherlands.
3 Department of Medical Microbiology Leiden University Medical Center Leiden The Netherlands.
4 Center for Infectious Disease Control National Institute for Public Health and the Environment (Rijksinstituut voor Volksgezondheid en Milieu) Bilthoven The Netherlands.