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The Flaviviridae include
almost 70 viruses, nearly half of which have been associated with
human disease. Flavivirus is a genus of the family Flaviviridae.
Flavivirus share a
common size (40-60 nanometres), 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 among the most
important arthropod-borne viruses worldwide and include dengue, yellow
fever, and Japanese encephalitis viruses.
Morbidity and mortality caused by these
viruses vary, but collectively they account for millions of
encephalitis, hemorrhagic fever, arthralgia, rash, and fever cases per
year.
Most of the members of this family are
transmitted between vertebrate hosts by arthropod vectors, most
commonly mosquitoes or ticks.
Transmission cycles can be simple or
complex depending on the hosts, vectors, the virus, and the
environmental factors affecting both hosts and viruses.
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MOSQUITO-BORNE VIRUSES :
-Dengue Virus:
-Yellow Fever Virus:
-Japanese
encephalitis virus:
-Murray Valley encephalitis virus:
-St. Louis Encephalitis
Virus:
-West
Nile Virus:
- TICK-BORNE
VIRUSES :
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Tick-borne encephalitis virus
- Omsk hemorrhagic fever virus:
- Kyasanur
Forest disease virus:
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Tick-borne flaviviruses.Adv
Virus Res. 2003;61:317-71
Tick-borne
encephalitis (TBE), one of the most dangerous neuroinfections in
Europe and Asia, is caused by tick-borne encephalitis virus (TBEV)
and currently involves approximately 11,000 human cases annually,
mostly in Russia. This chapter describes the main problems
associated with the epidemiology, ecology, pathogenesis, and
control of this disease. We have attempted to review the factors
that influence the incidence and distribution of TBE, and to
discuss possible reasons for the different clinical manifestations
including most commonly observed asymptomatic infections, fever
forms, acute encephalitis, and the less frequently registered
biphasic milk fever and chronic encephalitis. Epidemiologic data
concerning the other tick-borne flaviviruses, namely Louping ill
virus, Langat virus, and Powassan virus that also produce
encephalitis on a smaller scale, are also presented. Here we
describe the history and current epidemiological role of Omsk
hemorrhagic fever virus and Kyasanur forest disease virus, two
viruses that are genetically closely related to TBEV, but produce
hemorrhagic fever instead of encephalitis, and provide possible
explanations for these differences. The other viruses in the
tick-borne flavivirus group are also included despite the fact
that they do not play an essential epidemiologic role in humans.
This chapter contains a brief history of vaccination against TBE
including the trials with live attenuated vaccine and reviews the
modern trends in development of vaccine virus strains.
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