Medically, shingles is called herpes zoster, comprising a circumscribed set of inflamed blisters caused by the varicella zoster virus, which also gives you chickenpox.
In the Greek language, the word for girdle is zoster and shingles is half a girdle of small red spots, which turn into tiny balloons or vesicles.
The virus attacks one nerve supplying the skin, so the rash can occur anywhere on the body supplied by that particular nerve.
Unfortunately, when a child gets chickenpox some of the viruses causing the condition may escape destruction by the immune system of the body and lie dormant for years in the nerve ganglions of the peripheral nervous system - the parts of nerves near the spinal column.
As people get older, the dormant virus can 'wake up' and becomes activated, causing 'localised' chickenpox. The trigger for this is unknown, except that it must be a failure, of the
body's defence mechanism.
Many articles taken from 'A word with the doctor', by Dr. John Windsor.