from Duane J Gubler writing in Molecular Virology and Control of Flaviviruses:
The flaviviruses (genus Flavivirus) are among the most important pathogens infecting humans and domestic animals, causing hundreds of millions of infections annually. They have a global distribution and cause a broad spectrum of illness ranging from mild viral syndrome to severe and fatal hemorrhagic and neurologic disease. The genus is made up of a diverse group of 53 viral species that have evolved into three distinct groups with very different transmission cycles. The vector-borne group is transmitted among vertebrate hosts by hematophagous arthropods (mosquitoes and ticks), the no-known vector group is transmitted directly among vertebrate animals and the arthropod group is transmitted directly among arthropods. This chapter reviews the history, the present status and future trends of flaviviruses, using some of the more important species as case studies.
Further reading: Molecular Virology and Control of Flaviviruses