Flavivirus
Flavivirus is a genus of the family Flaviviridae. This genus includes the West Nile virus, Dengue fever virus, Tick-borne Encephalitis Virus, Yellow fever virus, and several other viruses which may cause encephalitis.
| Flavivirus | |
|---|---|
| |
| A TEM micrograph of the yellow fever virus | |
| Virus classification | |
| Group: | Group IV ((+)ssRNA)
|
| Family: | |
| Genus: | Flavivirus
|
| Type species | |
| Yellow fever virus | |
Flavivirus are share a common size 40-65 nm. Flaviviruses are named from the yellow fever virus, a type virus for the Flaviviridae family; flavus means yellow in Latin. Yellow fever in turn was named because of its propensity to cause yellow jaundice in victims.[2]
Flaviviruses share a common size (40-65 nm), symmetry (enveloped, icosahedral nucleocapsid), nucleic acid (positive-sense, single stranded RNA approximately 10,000–11,000 bases), and appearance in the electron microscope.
These viruses are transmitted by the bite from an infected arthropod (mosquito or tick). Human infections with these viruses are typically incidental, as humans are unable to replicate the virus to high enough titres to reinfect arthropods and thus continue the virus life cycle. The exceptions to this are yellow fever and dengue viruses, which still require mosquito vectors, but are well-enough adapted to humans as to not necessarily depend upon animal hosts (although both continue have important animal transmission routes as well).
Other virus transmission routes include handling infected animal carcasses, blood transfusion, child birth and through consumption of unpasteurised milk products. The transmission from animals to humans without an intermediate vector arthropod is thought to be unlikely. For example, early tests with yellow fever showed that the disease is not a contagious disease.