Tick-borne meningoencephalitis

Taxobox
name = "Tick-borne meningoencephalitis virus"
virus_group = iv
familia = "Flaviviridae"
genus = "Flavivirus"
species = "Tick-borne meningoencephalitis virus"

Tick-borne meningoencephalitis or Tick-borne encephalitis is a tick-borne viral infection of the central nervous system affecting humans as well as most other mammals. The virus can infect the brain (encephalitis), the membrane that surrounds the brain and spinal cord (meningitis) or both (meningoencephalitis). It is transmitted by the bite of infected deer- or sheep ticks or (rarely) through the non-pasteurized milk of infected cows. Sexual transmission has been documented in mice with vertical transmission to progeny. Sexual transmission with humans has never been documented.

Etiology

The responsible virus, "Tick-Borne Encephalitis Virus" (TBEV), is a member of the genus flavivirus. Other close relatives include Omsk hemorrhagic fever virus, Kyasanur forest disease virus, alkhurma virus, louping ill virus and the langat virus.

TBE virus has two subtypes:(a) European subtype (Tick vector: "Ixodes ricinus")(b) Far Eastern subtype (Tick vector: "Ixodes persulcatus")

Russia and Europe report between 10-12,000 human cases annually.Fact|date=February 2007 The disease is incurable once manifest, but infection can be prevented by vaccination, and the virus can be inactivated, halting disease progression. In humans, the disease is lethal in approximately 1.2% of cases and leaves 15-20% of its survivors with permanent neurological damage.Fact|date=February 2007 The former Soviet Union did a great deal of research on all tick borne disease including TBE viruses.

Diagnosis

The TBE virus may be present in a seronegative strain or subtype. In such cases a marker for TBE infection is elevated IFN-g in CSF.

Treatment

There are four main catgeories of treatment for TBE:Fact|date=February 2007
* interferon treatment (similar to interferon used for the treatment of Hepatitis C)
* antibiotic treatment for possible tickborne coinfections

Antibiotics

Although the TBE virus cannot be eradicated from the body, it can be inactivated.Fact|date=February 2007 It can also be activated.Fact|date=February 2007 Unfortunately, certain antibiotics activate the TBE virus while others have no effect. This is important because the TBE virus may be a coinfection with a "Borrelia burgdorferi" infection, Lyme disease, which is treated with antibiotics.Fact|date=February 2007 Russian scientists studied this matter for years and their findings were as follows: gentamicin exerts no activating effect while streptomycin and ten other antibiotics activate the virus.Fact|date=February 2007 They also found that the TBE virus is almost completely inactivated in mice by certain herbs: ledum, motherwort and blackcurrant.Fact|date=February 2007

Progressive form and Amyotrophic Lateral Sclerosis

The TBE virus is a slow virus; it can take decades to become fulminant.Fact|date=February 2007 This is termed the Progressive Form of the TBE Virus (PFTBE). In 1983 in Russia, a follow-up study was done of patients 2-22 years after having acute TBE. PFTBE was found in 68%, the "overwhelming majority" of these developing ALS, Amyotrophic Lateral Sclerosis.Fact|date=February 2007 The first isolation of a TBE virus connected with ALS was in 1975 when 70% of the ALS cases in Hamburg, Germany were found to have had contact with this virus.Fact|date=February 2007 In 1978, ALS was reproduced in laboratory animals by inoculation of the Schu virus, a TBE flavivirus, taken from the CSF of a patient with ALS.Fact|date=February 2007 In regard to the sexual and vertical transmission of the TBE virus, it is thought provoking that conjugal and familial ALS have both been documented.Fact|date=February 2007

References

*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*

Footnotes

External links

* [http://wwwn.cdc.gov/travel/yellowBookCh4-Tickborne.aspx Tickborne encephalitis] at Centers for Disease Control and Prevention