The family Flaviviridae includes many viruses of medical importance, for example, the arthropod-transmitted dengue, yellow fever, West Nile and Japanese encephalitis viruses. Recently, Zika virus has become of global public health importance. Hepattitis C virus within the genus Hepacivirus is a major cause of chronic liver disease and hepatocellular carcinoma. Vaccines are available for yellow fever, Japanese encephalitis and West Nile viruses. The treatment of hepatitis C virus infection through the use of antivirals is showing considerable promise. All flaviviruses contain a positive sense single-stranded RNA genome, divided into structural and non-structural protein coding regions.