Shingles and chickenpox are both caused by a single virus of the herpes family, known as varicella-zoster virus (VZV). The word herpes is derived from the Greek word "herpein," which means "to creep," a reference to a characteristic pattern of skin eruptions. VZV causes two different clinical illnesses:
- Varicella, or chickenpox, develops after an individual is exposed to VZV for the first time.
- Herpes zoster, or shingles, develops from reactivation of the virus later in life, usually many decades after chickenpox.
Most people get chickenpox from exposure to other people with chickenpox. It is most often spread through sneezing, coughing, and breathing. It is so contagious that few nonimmunized people escape this common disease when they are exposed to someone else with the disease.
When people with chickenpox cough or sneeze, they expel tiny droplets that carry the varicella virus. If a person who has never had chickenpox or never been vaccinated inhales these particles, the virus enters the lungs. From here it passes into the bloodstream. When it is carried to the skin it produces the typical rash of chickenpox.
People can also catch chickenpox from direct contact with a shingles rash if they have not been immunized by vaccination or by a previous bout of chickenpox. In such cases, transmission happens during the active phase when blisters have erupted but not formed dry crusts. A person with shingles cannot transmit the virus by breathing or coughing.
Review Date: 05/03/2011
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.