MicrobiologyBytes: Virology: HHV-3 Updated: September 11, 2007 Search

Varicella Zoster Virus (VZV / HHV-3)

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The complete genome of VZV genome is ~125kbp:

Herpesvirus genomes

HHV-3 infects a variety of human and animal cell types in vitro and gives rise to 2 distinct clinical syndromes:

  • Varicella (Chicken pox) - (nothing to do with chickens or pox!). Infection normally occurs in childhood (>90% of UK adults are seropositive), via respiratory tract or conjunctiva. After multiplication at the inoculation sites, virus spreads to bloodstream and reticuloendothelial system. Secondary multiplication involves skin and mucosa, producing vesicles filled with very high titres of infectious virus! Complications are rare, but may include CNS infection.
  • Zoster (Shingles) - After primary infection, virus persists in sensory ganglia of CNS. It is not clear if this is a latent or a persistent infection, but 'reactivation' after many years leads to infection and tissue damage to dermatosome served by infected ganglia - most serious when cranial nerves are involved, affecting face/head - can lead to blindness.

Herpesvirus infections of the nervous system. Nat Clin Pract Neurol. 2007 3: 82-94

Incidence of HHV infection

Therapy - acyclovir. Not commonly used for primary varicella. Although complications are rare, there is some evidence that the number of adult deaths from chickenpox is increasing slightly in England and Wales (Rawson H, et al. Deaths from chickenpox in England and Wales 1995-7: analysis of routine mortality data. BMJ 2001 323: 1091-3). This virus presently causes about 20 adult deaths in England and Wales each year.

Although vaccines have been available in the USA for several years, the first vaccine for use in the UK was approved on 31st July 2002.

UK Department of Health current vaccination guidelines

 

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