Shingles rash (red) and blisters (orange) on the chest of a 90-year-old man. Shingles (herpes zoster) is the result of infection of sensory nerves by the varicella-zoster virus, which also causes chickenpox. The virus can remain dormant in the nerve tracts that emerge from the spine. When re-activated, a rash and blisters appear on skin supplied by the affected sensory nerve. The blisters are filled with fluid that contains virus particles.