Distinction between shingles, chickenpox

"Is my son sick because he's been around my dad?" the stressed-out mother wanted to know. It was bad enough that her father was suffering from a painful case of shingles, now her toddler was starting with a fever.

Since it was a night call and I didn't have access to the little boy's records, I asked the mom if her son had been vaccinated against chickenpox. All his shots were up to date, she assured me, and yes, she did recall that he'd had his chickenpox shot at his 15-month checkup. That being the case, I told the mother that it was unlikely that grandpa had passed his illness on to his grandson.

Shingles, also known as herpes zoster, is a skin condition that usually occurs in adults. It is caused by the varicella zoster virus, which is the same bug that causes chickenpox.

Chickenpox virus can enter the body the old-fashioned way, through infection caused by person-to-person transmission, or through the modern technique of vaccination. Either experience provides pretty good protection against future chickenpox disease.

Once the chickenpox virus is introduced, however, it remains in the individual, lying dormant in the nervous system. During periods of stress, illness, or in some cases for unknown reasons, this virus can reactivate as shingles. These blistery skin lesions usually affect one area of the body, often appearing on the trunk in a cluster along a dermatome, or nerve band.

While shingles and chickenpox are caused by the same virus, it's important to note a distinction in how these diseases develop. Chickenpox patients are highly contagious, sharing their varicella zoster virus with others through infected respiratory droplets and through skin contact. Susceptible individuals (those who have had neither the disease nor the vaccination) can catch chickenpox, but they cannot "catch" shingles.

Shingles sufferers are contagious only through direct skin contact. If a susceptible person touches shingles blisters, he has a decent chance of coming down with a case of chickenpox.

He won't "catch" shingles from this person, as you can't reactivate a virus you've never had before. Keeping shingles lesions covered until they have all crusted over (typically for a three- to five-day period), and practicing good hand washing reduces the risk of potential chickenpox transmission from shingles.

According to the National Institutes of Health, approximately 25 percent of the adult population will experience shingles, usually some time after age 40.

The condition is seen less often in childhood, but immune-compromised children and kids who have had chickenpox during infancy are known to be at higher risk of developing pediatric shingles.

Though shingles theoretically can occur in an individual who has previously received the chickenpox vaccine ("attenuated," or weakened, virus exposure), these patients are considered to be at less risk for shingles than those who have had chickenpox disease naturally ("wild" virus exposure).

Antiviral medications can help some shingles patients by shortening the course of the illness and decreasing disease severity.

As for disease prevention, adults 60 years of age and older can ask their doctors whether they are eligible for the new shingles vaccine, licensed in 2006.

• Dr. Helen Minciotti is a mother of five and a pediatrician with a practice in Schaumburg. She formerly chaired the Department of Pediatrics at Northwest Community Hospital in Arlington Heights.