Overview

Flaviviridae is a family of enveloped viruses with a single‑stranded positive‑sense RNA genome. Many members are arthropod‑borne agents of human disease, transmitted by mosquitoes or ticks, but the family also contains viruses that circulate without insect vectors. The family name comes from yellow fever virus: flavus is Latin for "yellow," a reference to the jaundice seen in that disease.

Structure and genome

Virions are roughly spherical and enveloped, and the genome is a single open reading frame of roughly 9–13 kilobases that is translated into one long polyprotein. That polyprotein is cleaved by viral and host proteases into structural proteins (including the capsid and envelope proteins) and multiple nonstructural proteins that mediate replication and assembly. Key nonstructural proteins include an RNA‑dependent RNA polymerase and a multifunctional protease/helicase.

Genera and notable viruses

  • Flavivirus — many important arboviruses, such as dengue virus, yellow fever virus, Zika virus, West Nile virus and tick‑borne encephalitis virus.
  • Hepacivirus — best known for hepatitis C virus, a major cause of chronic liver disease transmitted by blood.
  • Pestivirus — includes economically important veterinary agents like bovine viral diarrhea virus and classical swine fever virus.
  • Pegivirus — human pegivirus (formerly GB virus C) and related viruses; these usually persist without a clear disease association.

Transmission, disease and public health

Flaviviruses in the genus Flavivirus are commonly spread by arthropod vectors and cause a spectrum from mild febrile illness to severe neuroinvasive or hemorrhagic disease. Hepaciviruses and pegiviruses are typically bloodborne and associated with long‑term infections. Control strategies differ by virus: vaccination and vector control are central for many mosquito‑borne flaviviruses, while antiviral drug development and blood‑safety measures dominate for bloodborne genera.

Vaccines exist for some members (for example, an effective live attenuated vaccine for yellow fever), and the past two decades have seen major advances in antiviral therapy for hepatitis C virus. Diagnosis relies on molecular tests, serology and clinical epidemiology; public health responses emphasize surveillance, vector management and vaccination where available.

History, taxonomy and research

Research on yellow fever and other arthropod‑borne diseases in the early 20th century helped define this group. Modern taxonomy divides the family into several genera based on genetic and biological properties, and classification continues to evolve as genomic data accumulate. Ongoing research focuses on virus–host interactions, vaccine development, antiviral agents and improved diagnostics.

Further information

For authoritative taxonomic summaries and updates see the international reports and reviews: taxonomic resources, general overviews at public health agencies: public health summary, clinical guidance and diagnostics: clinical resources, and current research repositories: research databases.