More than 38 viral species are transmitted by
ticks. Virus-to-tick host relationships are very specific and less than 10% of all tick species (Argasidae and Ixodidae) are known to be carriers of arboviruses. Tick-borne viruses are found in six different virus families (
Asfarviridae, Reoviridae, Rhabdoviridae, Orthomyxoviridae, Bunyaviridae, Flaviviridae). Tick-borne flaviviruses are among the most important viruses in the world, primarily Europe and Asia. Tick-borne encephalitis causes between 10,000 and 15,000 human cases every year in Europe and Asia. Most of these viruses are needed for veterinary medicine. Several other tick-borne flaviviruses have not been known to cause human nor animal diseases, and their potential pathogenicity for humans and animals is unknown/unavailable. Alterations in human behavior, land use, or
climate may change the actual geographical distribution and transmission intensity so that tick-borne flaviviruses are potentially relevant of the environment and may increase in medical importance. ==Historic findings==