[West Nile virus unexpectedly in the Netherlands].

West Nile virus (WNV) was first detected in birds, mosquitoes and subsequently in humans in the Netherlands in 2020. In 2016 , we had discussed the factors that influence the introduction, establishment and dissemination of WNV in the Netherlands and considered the probability that each of these three phases could occur in the Netherlands, and cause West Nile fever in humans, still relatively small. In the current article we evaluate on the basis of our reasoning at the time, whether we have missed important factors and/or whether new factors have appeared on the horizon. We then explain what the findings/ this progressive insight of 2020 mean for the near future.