Varicella zoster virus
The varicella - zoster virus ( VZV) - also written varicella -zoster virus and referred to as Human herpes virus -3 - is a virus from the group of those eight herpes viruses that can cause diseases in humans and other vertebrates. This DNA virus is cause of chickenpox and shingles.
Features
VZV is membranumhüllt containing double-stranded DNA (dsDNA ) and an icosahedral capsid with 162 capsomeres; the virion is 150-200 nm in diameter in size. The VZV belongs to the genus Varicellovirus, to the subfamily of Alphaherpesvirinae and of the Herpesviridae family. The herpes simplex virus is closely related, since it shares with the latter a large part of its genome.
Like all herpesviruses, VZV is also very well adapted to humans as its only natural host. A total of 95 % of the German population, according to the Robert Koch Institute antibodies against VZV can be detected.
Transmission and infection episodes
First illness
The virus is very easily transmitted as droplet infection due to the highly contagious and usually results in initial contact to the appearance of chicken pox. These represent in previously healthy children is a harmless disease and lead to a life-long immunity. At the same time the VZ viruses bind via so-called ligands to receptors of the sensory nerve fibers enter by endocytosis in the axon and get into this (ie intra- axonal ) in the corresponding sensitive dorsal root ganglia or corresponding ganglia of the cranial nerves high ( Virusaszension ) to live there long to remain ( Erregerpersistenz ).
Secondary disease
After years of dormancy ( latency phase) different triggers can especially in a weakening of the cellular immune system, as occurs more frequently with increasing age, allow a renewed virus replication. This will either remain asymptomatic or causes now the second disease with (shingles ) or without vesiculation ( zoster sine herpete ). The rapid rise of antibodies in terms of a so-called booster means that there is a pronounced virus replication in only one or a few ganglia and can dismount the excitation along the corresponding nerve in the respective nerve segment ( Virusdeszension ). Therefore, in the area of the tribe it comes to that half side - belt-like spread, which owes the name of the disease.
The usually rapid antibody formation is also the reason why there is rarely a second occurrence of shingles. However, about half of those over 85 years, an episode during their life has gone through.
Prevention and Vaccination
Vaccination against varicella is recommended by the Standing Committee on Vaccination (STIKO ) from the 11th month of life. There are several vaccines that can be inoculated in the early childhood. This vaccination is carried out with an attenuated live virus strain, in order to achieve the best possible protection against the normal wild-type virus. A list of the currently available vaccines offers the Paul Ehrlich Institute (PEI ) on your website.
The main argument for vaccination is the fact that not only the relatively harmless chickenpox be prevented, but also the complications of VZV infection:
- Perinatal chickenpox, that is, a chickenpox infection of the newborn by a fresh fell ill mother who has a child mortality rate of up to 30 %
- Congenital chickenpox, that is, a chickenpox infection during pregnancy, which can lead to serious developmental problems in the unborn child
- Chickenpox meningitis with possible neurological deficits
- Varicella pneumonia: a serious form of pneumonia, rare but dangerous
- Generalized zoster: a resurgence of the virus with generalization or involving vital organs (CNS, sensory organs, optic nerve, inner ear, etc.)
Since 2006, a live vaccine ( Zostavax ®) for the vaccination of 50 years is permitted against the virus, which contains a higher dose of the so-called plaque-forming units. You should reduce at -risk groups, the risk of herpes zoster after take gehabter initial infection. A recommendation of the Standing Committee on Vaccination is still pending.
System
- Family Herpesviridae Subfamily Alphaherpesvirinae Genus simplex virus Species herpes simplex virus 1 (HSV -1) or (HHV -1)
- Species herpes simplex virus 2 (HSV -2) or (HHV -2)
- Species herpes B virus ( herpesvirus simiae )
- Species varicella-zoster virus (VZV) or Human herpesvirus 3 (HHV -3)
- Species Suides herpesvirus 1 ( pseudorabies virus)