Herpes zoster is the secondary manifestation of an infection with the Varicella-zoster-virus, which after primary infection (chicken pox) lifelong stays persistent in the glial cells of the spinal ganglia.The disease is prevalent all over the world and mostly occurs sporadically. Incidence is about 400/100 000 inhabitans, prevalence 80/100 000. Peak age for the disease is between 50 and 70 years, with no difference between the sexes. The infection entails lifelong immunity.