Varicella zoster virus
| Varicella zoster virus | ||||||||||||||||||||
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Varicella zoster virus (VZV). |
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| Human alphaherpesvirus 3 | ||||||||||||||||||||
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| HHV3, VZV | ||||||||||||||||||||
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The varicella zoster virus ( VZV ) (also varicella zoster virus , scientifically human alphaherpesvirus 3 , HHV3) is a virus from the group of eight herpes viruses that can cause diseases in humans and other vertebrates. This DNA virus causes chickenpox and shingles .
features
The VZV is membrane-coated, contains double-stranded DNA (dsDNA) and an icosahedral capsid with 162 capsomeres ; the virion is 150-200 nm in diameter. The VZV belongs to the genus Varicellovirus , to the subfamily of Alphaherpesvirinae and to the family of Herpesviridae . It is closely related to the herpes simplex viruses because it shares a large part of its genome with them .
Like all herpes viruses, the VZV is also very well adapted to humans as their only natural host . According to the Robert Koch Institute, antibodies against VZV can be detected in a total of 95% of the German population .
Transmission and consequences of infection
First illness
Due to its high contagiousness , the virus is usually transmitted very easily as a droplet infection and leads to the appearance of chickenpox on initial contact . These represent a harmless disease in previously healthy children and lead to lifelong immunity . At the same time, the VZ viruses bind to receptors of the sensitive nerve fibers by means of so-called ligands , reach the axon by means of endocytosis and rise in this (i.e. intra-axonally) into the corresponding sensitive spinal ganglia or corresponding ganglia of the cranial nerves up ( virus ascension ) to be there for life to remain ( pathogen persistence ).
Second illness
After years of rest (latency phase), various triggers can enable the virus to replicate again, especially when the cellular immune system is weakened , as often occurs with increasing age. This either remains symptom-free or causes the second disease with ( shingles ) or without the formation of blisters ( zoster sine herpete ). The rapid increase in antibodies in the sense of a so-called boosting leads to a pronounced virus multiplication only in one or a few ganglia and the pathogens can descend along the corresponding nerves into the respective nerve segment ( virus descent ). In the area of the trunk there is therefore that half-sided belt-shaped spread that the disease owes its name to.
The usually rapid antibody formation is also the reason why a second occurrence of shingles rarely occurs. However, around half of those over 85 have had an episode in their lifetime.
Prevention and vaccination
Vaccination against varicella is recommended by the Standing Vaccination Commission (STIKO) from 11 months of age. There are several varicella vaccines (e.g. Varilrix , Varivax ) that can be vaccinated in early childhood. This vaccination is carried out with a weakened, live pathogen strain in order to achieve the best possible protection against the actual wild virus. The Paul Ehrlich Institute (PEI) offers a list of the currently available vaccines on its homepage.
The main argument in favor of vaccination is that it not only prevents the relatively harmless chickenpox, but also the complications of a VZV infection:
- perinatal chickenpox , d. H. a chickenpox infection of the newborn from a newly ill mother, which has a fatality rate of up to 30% for the child
- congenital chickenpox ; d. H. a chickenpox infection during pregnancy , which can lead to serious developmental disorders in the unborn child
- Chickenpox meningitis with possibly neurological deficits
- Varicella pneumonia : a serious form of pneumonia, rare but dangerous
- generalized zoster : a resurgence of the virus with generalization or involving important organs ( CNS , sensory organs, optic nerve , inner ear, etc.)
A live vaccine ( Zostavax ) has been approved for vaccination against the virus from the age of 50 since 2006 and contains a higher dose of the so-called plaque - forming units. It is intended to reduce the risk of herpes zoster in risk groups even after the initial infection . However, Zostavax is not recommended as a standard vaccination by the STIKO due to its limited effectiveness and its limited duration of action. Since December 2018, the Standing Vaccination Commission has recommended all people aged 60 and over (standard vaccination) to be vaccinated with an adjuvanted herpes zoster subunit (HZ / su) dead vaccine ( Shingrix ) to prevent herpes zoster (HZ) and postherpetic neuralgia ( PHN) . The commission recommends that people with an underlying disease or immune deficiency should be vaccinated from the age of 50 (indication vaccination).
therapy
For the antiviral treatment of VZV infections, the main antivirals available are acyclovir , alternatively also valaciclovir , famciclovir and brivudine . Foscarnet can be used for aciclovir resistance . In the context of a perinatal infection, the varicella-zoster immunoglobulin, which is also used for post-exposure prophylaxis in seronegative pregnant women, is administered.
Systematics
For the external system, see Varicellovirus and Alphaherpesvirinae .
Reporting requirement
In Germany, direct or indirect evidence of the varicella zoster virus must be reported by name in accordance with Section 7 of the Infection Protection Act , provided that evidence indicates an acute infection.
Individual evidence
- ↑ a b c d e ICTV: ICTV Taxonomy history: Human alphaherpesvirus 1 , EC 51, Berlin, Germany, July 2019; Email ratification March 2020 (MSL # 35)
- ↑ Epidemiological Bulletin of the RKI, No. 46; November 2000 Robert Koch Institute
- ↑ Recommendations of the Standing Vaccination Commission Robert Koch Institute
- ↑ Vaccines against varicella (chickenpox) Paul Ehrlich Institute
- ↑ RKI - Varicella - Shingles (Herpes zoster): Answers to frequently asked questions about the disease and vaccination. Retrieved December 20, 2019 .
- ↑ Scientific justification of the STIKO for the recommendation of a vaccination with the herpes zoster subunit dead vaccine Robert Koch Institute
- ^ Marianne Abele-Horn: Antimicrobial Therapy. Decision support for the treatment and prophylaxis of infectious diseases. With the collaboration of Werner Heinz, Hartwig Klinker, Johann Schurz and August Stich, 2nd, revised and expanded edition. Peter Wiehl, Marburg 2009, ISBN 978-3-927219-14-4 , p. 306 f.