WEST NILE VIRUS: PERSPECTIVE IN THE VERTEBRATE WORLD

West Nile virus, an arthropod-borne virus belonging to the family Flaviviridae, genus Flavivirus, is transmitted in a cycle involving mosquitoes and birds. For many decades it had been recognized in Africa, Asia and the south of Europe. In 1999 it appeared by first time in North America and its circulation has been documented in México, Jamaica, Dominican Republic, Guadalupe, Cuba, Puerto Rico, El Salvador and Colombia. Only recently it has been associated with an increasing number of outbreaks of encephalitis in humans and equines, as well as infections in vertebrates of a wide variety of species. A wide variety of vertebrates, including more than 150 bird species and at least 30 other vertebrate species, are susceptible to WNV infection. The outcome of infection depends on the species, the age of the animal, its immune status and the pathogenicity of the WNV isolate. WNV infection of various birds, especially Passeriforms, but also of young chickens and domestic geese, results in high-titred viremia that allows arthropod-borne transmission. The role of vertebrates in direct, non-arthropod-born transmission, such as via virus-contaminated organs, tissues or excretions is less well characterized. The increased importance of WNV infections has led to the development of killed, live attenuated, DNA-recombinant and chimeric veterinary vaccines. In this article, are reviewed the role of vertebrates in the WNV infection and its importance in medicine veterinary. Future perspectives are discussed as well as its impact in animal health because of its recent introduction to Colombia.