Shingles and Chickenpox (Varicella-Zoster Virus) - Introduction

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It is not clear why the varicella 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 immunodeficient 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 as well). Herpes viruses are similar in shape and size and reproduce within the structure of a cell. The particular cell depends upon the specific virus. The human herpes viruses are:

• Herpes Simplex Virus 1 (HSV-1; causes cold sores and sometimes genital herpes)
• Herpes Simplex Virus 2 (HSV-2; causes genital herpes and sometimes cold sores)
• Varicella-zoster Virus (VZV; causes chickenpox and shingles)
• Cytomegalovirus (CMV; causes mononucleosis and retinitis)
• Epstein-Barre Virus (EBV; causes mononucleosis
• Human Herpesvirus 6 (HHV6; causes roseola)
• Human Herpesvirus 7 (HHV7; causes roseola)
• Human Herpesvirus 7 (HHV8; causes Kaposi's sarcoma)

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 for a lifetime. [For more information, see In-Depth Report #52: Herpes simplex.]

Review Date: 03/15/2007
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital.