An increasing number of insect-specific flaviviruses (ISFVs) are recognized worldwide.
ISFVs seem exclusive of insects, no vertebrate hosts have been identified to date.
Some ISFVs are detected in several mosquito species, some in mosquitoes and sandflies.
ISFVs are detected worldwide, often in different countries and continents.
The taxonomic relation between ISFVs and known flaviviruses remains to be elucidated.