There are more than five hundred known arthropod-borne viruses (arboviruses) all around the world and approximately hundred of them may cause disease in humans. During the past 20 years there has been a dramatic resurgence or emergence of epidemic arboviral diseases affecting both humans and domestic animals. Many factors play important roles in the emergence of arboviral diseases like Yellow Fever, Dengue, West Nile encephalitis, and of other diseases such as malaria and leishmaniasis in countries where they have not been previously encountered and in the increase in incidences where they have been under control. Some of these are demographic factors such as global population increase and uncontrolled urbanization; social changes such as modern transportation, human encroachment on natural disease hotspots; changes in agricultural activities such as the use of new irrigation techniques; deforestation; genetic changes in the pathogens; preventive measures and probably global climate changes. Mosquitoes are among the most important vectors carrying viruses belonging to Alphavirus, Flavivirus, Bunyavirus and Phlebovirus genera. All of the above factors have contributed to the increase in mosquito populations and closer contact between humans and mosquito vectors. West Nile virus notable after the epidemic of 1996 in Romania in Europe is one of the latest examples indicating that viruses can jump continents and produce epidemics. In this review article, the distribution of West Nile virus and its principal vectors and also its importance by means of public health, have been discussed.