Shingles and Chickenpox (Varicella-Zoster Virus) - Introduction

(Page 2)

Herpes Zoster (Shingles)

The varicella-zoster virus also travels to nerve cells called dorsal root ganglia. These are bundles of nerves that transmit sensory information from the skin to the brain. Here, the virus can hide from the immune system for years, often for a lifetime. This inactivity is called latency.

Click the icon to see an image of shingles.

If the virus becomes active after being latent, it causes the disorder known as shingles or herpes zoster. The virus spreads in the ganglion and to the nerves connecting to it. Nerves most often affected are those in the face or the trunk. The virus can also spread to the spinal cord and into the bloodstream.

---

---

Shingles itself can develop only from a reactivation of the varicella-zoster virus in a person who has previously had chickenpox. In other words, shingles itself is never transmitted from one person to another either in the air or through direct exposure to the blisters.

It is not clear why the varicella-zoster virus reactivates in some people but not in others. In many cases, the immune system has become impaired or suppressed from certain conditions such as AIDS, other immunodeficiency diseases, or certain cancers or drugs that suppress the immune system. Aging itself increases the risk for shingles.

Other Herpes Viruses

The varicella-zoster virus belongs to a group of herpes viruses that includes eight human viruses (it also includes animal viruses). Herpes viruses are similar in shape and size and reproduce within the structure of a cell. The particular cell depends upon the specific virus. Human herpes viruses include herpes simplex virus 1 (HSV-1), which usually causes cold sores, and herpes simplex virus 2 (HSV-2), which usually causes genital herpes. Cytomegalovirus (CMV), which causes mononucleosis-like illness and retinitis, and Epstein-Barre Virus (EBV), the cause of classic mononucleosis, are also human herpes viruses.

All herpes viruses share some common properties, including a pattern of active symptoms followed by latent inactive periods that can last for months, years, or even a lifetime. [For more information, see In-Depth Report #52: Herpes simplex.]

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.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org).