Herpes zoster (shingles) normally occurs in a limited area that follows a dermatome (see the "dermatome" picture). In individuals with damaged immune systems, herpes zoster may be widespread (disseminated), causing serious illness. Herpes zoster is caused by the same virus that causes chickenpox.
Review Date 5/1/2015
Updated by: Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.