If you had chickenpox as a child, you might have thought it was gone for good. Unfortunately, there's a grownup version of the disease, called shingles.

It's caused by the same herpes zoster virus that left you red, itchy and miserable as a kid. Shingles is a burning, painful skin rash marked by blisters that can last up to five weeks and pain that can linger for months or even years.

The good news is that most adults will never have the condition. Only about 20 percent of people who had chickenpox as children will go on to develop shingles in adulthood.

Scientists at The University of Texas Medical School in Houston recently discovered that family history may help explain why some people are more susceptible to shingles than others. The more close relatives you have with shingles, the greater your risk of developing the condition.

For the study, researchers examined data collected from more than a thousand patients. Of the more than 500 patients diagnosed with shingles, 39 percent reported knowing a blood relative who suffered from the same condition. Of the patients who had never developed shingles, only 11 percent knew of a blood relative with the disorder.

Although shingles may occur at any age, it's most common after the age of 60. After causing a bout of chickenpox, the herpes zoster virus takes up residence in nerves along the spinal cord, where it can remain in hibernation for a lifetime.

If you've never had shingles, it's because your immune system is holding the herpes zoster virus at bay, preventing it from attacking your body a second time. Unfortunately, the virus can be reactivated whenever the immune system is weakened.

Advancing age, illness, physical trauma and emotional stress can bring the virus out of hiding. After reactivation, the virus travels away from the spinal column along nerve fibers, marking its path with painful blisters.

The blisters typically erupt in clusters on the skin overlying those nerves, on one side of the face or body. The pattern of the rash gives the disease its name: "Shingles" comes from the Latin word for belt. Unlike chickenpox, shingles is more painful than itchy, and the slightest contact with the sensitive area can be excruciating.

Most folks with the condition make a complete recovery in three to four weeks. Approximately 25 percent of shingles patients have pain that lasts longer, lingering for months, years or even for the rest of their lives.

This condition, called post-herpetic neuralgia, occurs as a result of damage to the affected nerves. Individuals with post-herpetic neuralgia may experience continuous, unrelenting pain.

Doctors often prescribe antiviral medications for the treatment of shingles. Although these drugs were once believed to be effective only when started within 72 hours of developing symptoms, current research indicates that the drugs may be beneficial even when they're taken a little later in the course of the illness.

Studies show that when shingles patients over the age of 50 are treated with these medications in a timely manner, their chances of developing post-herpetic neuralgia are reduced by half. Thanks to the development of the chickenpox vaccine in 1995, vaccinated individuals will likely face a lower risk of developing shingles during adulthood.

Older adults who missed out on the chickenpox vaccine may opt to have the shingles vaccine, which was approved in 2006 for use in individuals over the age of 60. Use of the vaccine is currently being studied in people as young as 50 years of age.

If you have at least one shingles-suffering relative, you're an excellent candidate for the vaccine, since your risk for developing the condition is twice as high as it would be if you had no shingles-suffering relatives. In studies of approximately 38,000 people ages 60 and older throughout the United States, the vaccine reduced the occurrence of shingles by about half.

Among individuals who were vaccinated but still developed shingles, the duration of pain was shorter. Vaccination was also associated with a reduced risk of developing post-herpetic neuralgia.

The vaccine is generally safe and well tolerated, but it isn't recommended for people who have a weakened immune system caused by corticosteroids or other specific drugs, radiation treatment or various health conditions, including cancer.

If you've got a close family member with shingles, ask your doctor about the shingles vaccine. One quick injection might help prevent a lifetime of pain.

Rallie McAllister is a board-certified family physician, speaker and the author of several books, including "Healthy Lunchbox: The Working Mom's Guide to Keeping You and Your Kids Trim." Her website is www.rallieonhealth.com. To find out more about Rallie McAllister, M.D., and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate Web page at www.creators.com.

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