[Varicella and herpes zoster. Part 1: virology, epidemiology, clinical picture, laboratory diagnostics].

Varicella-zoster virus (VZV), known as one of the eight human herpesviridae, shows a ubiquitous distribution and is the cause for acute exanthema in childhood (chickenpox). VZV is highly infectious, spread by respiratory droplets and direct contact with fluid in vesicles. As a characteristic of the alpha-herpesviridae, VZV establishes latency in the nucleus of the paraspinal cells. Reactivation of VZV (zoster) is possible in all infected persons, but becomes more common with increasing age and a decline of VZV-specific cell-mediated immunity. Immunocompromised patients and older people (> 50 years) have an increased risk for a severe course of disease. The postherpetic neuralgia (PHN), as one of the most common and feared complications, is defined as a neuropathic pain (burning character), which persists for > 6 weeks after onset of disease and needs adequate antiviral and pain treatment.