Shingles and Chickenpox (Varicella-Zoster Virus) - Risk Factors

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Most schools allow children with chickenpox back 10 days after onset. Some require children to stay home until the skin has completely cleared, although this is not necessary to prevent transmission.

Risk Factors for Shingles (Herpes Zoster)

About 500,000 cases of shingles occur each year in the U.S. Anyone who has had chickenpox has risk for shingles later in life, which means that 90% of adults in the U.S. are at risk for shingles. Shingles occurs, however, in 10 - 20% of these adult over the course of their lives, so certain factors must exist to increase the risk for such outbreaks.

The Aging Process. The risk for herpes zoster increases as people age, and the overall number of cases will undoubtedly increase as the baby boomer generation gets older. One study estimated that a person who reaches age 85 has a 50% chance of having herpes zoster. The risk for postherpetic neuralgia (PHN) is also highest in older people with the infection and increases dramatically after age 50. PHN is persistent pain and is the most feared complication of shingles.

Immunosuppression. People whose immune systems are impaired from diseases such as AIDS or childhood cancer have a risk for herpes zoster that is much higher than those with healthy immune systems. Herpes zoster in people who are HIV-positive may be a sign of full-blown AIDS. Certain drugs used for HIV, called protease inhibitors, may also increase the risk for herpes zoster.

Cancer. Cancer places people at risk for herpes zoster. At highest risk are those with Hodgkin's disease (13 - 15% of these patients develop shingles). About 7 - 9% of patients with lymphomas, and between 1 - 3% of patients with other cancers, have herpes zoster. Chemotherapy itself increases the risk for herpes zoster.

Immunosuppressant Drugs. Patients who take certain drugs that suppress the immune system are at risk for shingles (as well as other infections). They include:

• Azathioprine (Imuran)
• Chlorambucil (Leukeran)
• Cyclophosphamide (Cytoxan)
• Cyclosporine (Sandimmune, Neoral)
• Cladribine (Leustatin)