Causes and Risk Factors

Shingles is a skin rash caused by the same virus that causes chickenpox. This virus is called the Varicella zoster virus (VZV) and is in the Herpes family of viruses. There is only one cause for shingles and that is the re-infection of the VZV.

After an individual has chickenpox, this virus lives in the nervous system and is never fully cleared from the body. Under certain circumstances, such as emotionalstress, immune deficiency (from AIDSor chemotherapy), or with cancer, the virus reactivates and causes shingles. In most cases of shingles, however, a cause for the reactivation of the virus is never found. Anyone who has ever had chickenpox or the chickenpox vaccine is at risk for the development of shingles.

If an adult or child is exposed to the herpes zoster virus and has not had chickenpox as a child or received the chickenpox vaccine, a severe case of chickenpox may develop, rather than shingles.

Herpes zoster can be contagious through direct contact in an individual who has not had chickenpox, and therefore has no immunity. Herpes zoster may affect any age group, but it is much more common in adults over 60 years old, in children who had chickenpox before the age of one year, and in individuals whose immune system is weakened.

Risk Factors

Advanced age
• Problems with the immune system
• Chickenpox during pregnancy.

Advanced Age
About 25 percent of all adults, mostly otherwise healthy, will get shingles during their lifetime, usually after age 40. The incidence increases with age. For example, shingles is 10 times more likely to occur in adults over 60 than in children under 10.

Immune System Problems
Your immune system is the part of your body that fights off infections. Age can affect your immune system. So can an HIV infection (or AIDS), cancer, cancer drugs, radiation treatments, or an organ transplant. Even stress or a cold can weaken your immune system for a short time and put you at risk for shingles.

Chickenpox During Pregnancy
Youngsters whose mothers had chickenpox late in pregnancy -- 5 to 21 days before giving birth -- or who had chickenpox in infancy have an increased risk of pediatric shingles. Sometimes these children are born with chickenpox or develop a typical case within a few days.

http://www.medicinenet.com/shingles/article.htm

http://www.medicinenet.com/shingles/article.htm

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