A large, heterogenous group of RNA viruses, most ranging from 40 to 100 nm or more in diameter, and divisible into groups on the basis of characteristics of the virions. There are over 500 species, which are distributed among several families (Togaviridae, Flaviviridae, Bunyaviridae, Arenaviridae, Rhabdoviridae, Reoviridae) have been recovered from arthropods, bats, and rodents, and most, but not all, are arthropod-borne. These taxonomically diverse animal viruses are unified by an epidemiological concept, i.e., transmission between vertebrate hosts by blood-feeding (hematophagous) arthropod vectors, such as mosquitoes, ticks, sandflies, and midges.. Although about 100 species can infect man, in most instances diseases produced by these viruses are of a very mild nature and difficult to distinguish from illnesses caused by viruses of other taxonomic groups. Apparent infections may be separated into several clinical syndromes: undifferentiated type fevers (systemic febrile disease), hepatitis, hemorrhagic fevers, and encephalitides. Syn: arborvirus.


[ar, arthropod, + bo, borne, + virus]