West Nile virus in Europe and Africa: still minor pathogen, or potential threat to public health?

Until 1999 the West Nile virus had been reported only in the "Old world" and particularly in Europe, Africa, Middle East and Asia where it was responsible only for sporadic or size-and-time-limited outbreaks in humans and equines. The sudden and unexpected emergence of WN in New York in 1999, followed by a rapid and huge extension to the whole North America in less than four years, made health authorities aware of the potential of previously forgotten viruses to become a threat to public health. The present review will focus on the epidemiology of West Nile virus in Europe and Africa during the last five decades. The recent re-emergence of WN activity in some European countries will be discussed regarding the current actuality of WN in the Americas.