Flavivirus

Abstract

The Flavivirus genus currently includes 53 viral species, most of them transmitted by mosquitoes and tick bites and others with not known vector and specific insect flavivirus. Flaviviruses comprise important arthropod-transmitted human pathogens, including yellow fever virus (YFV), Dengue virus (DENV), Japanese encephalitis virus (JEV), West Nile virus (WNV), and tick-borne encephalitis virus (TBEV). DEN viruses are globally expanded and are the most important mosquito-borne disease after malaria. Also with a worldwide distribution, YFV still cause mortality events around the world. Besides human vaccination campaign, enzootic foci remain active triggering emerging events for this pathology. West Nile virus, endemic in Old World countries, was introduced to American continent by 1999. It became an important human and veterinary pathogen due to its virulence in human beings, horses, and wild birds (especially in corvids). Antigenically closely related, St. Louis encephalitis virus co-circulates with WNV in American continent. Since 2002, it reemerged in the south cone of South America as a human encephalitis etiological agent. Tick-borne encephalitis virus still causes human encephalitis outbreaks in Eastern Europe and Russia. Zika virus with endemic activity in Africa and Polynesia became an emerging flavivirus with outbreaks reported in South America (Brazil, Colombia, Easter Island, and several other areas). In this chapter, authors will focus in general aspects of flaviviruses and their diseases, their spatial and temporal distributions patterns, ecology, epidemiology, pathogeny, and phylodynamics. Moreover, factors affecting their epidemiology and emergence are emphasized. Due to the great importance and amount of knowledge on dengue and yellow fever, these diseases deserved separated chapters (Chaps. 7 and 8).