The WHO recently reported that a man from the Netherlands returned home due to an illness. After returning home, the man found at he had come down with yellow fever.
According to Reuters, the young man traveled to West Africa in mid-November last year. He visited the nations of Gambia and Senegal. They are neighboring countries and are positioned in such a way that Gambia is almost entirely surrounded by Senegal. The countries share the north Atlantic Ocean along the shores of West Africa.
For many countries, a yellow fever infection is a dangerous, but fairly regular occurrence. But some countries, like the Netherlands, have almost no experience with the virus.