NEW YORK, June 13 (Reuters) -- About one out of five people will at some point in their lives suffer an attack of shingles, a reactivation of the chickenpox virus that causes a painful eruption of skin blisters, most often on the chest or back.
Now, a new study has found that even though attacks of shingles have risen over the past 40 years, serious side effects have remained relatively unchanged. About 14% of people who developed shingles, known medically as herpes zoster, developed complications two months after the attack, according to the report in the Archives of Internal Medicine.
And a second study in the same journal has found that older people, who are at greater risk for shingles in the first place, are also most likely to get complications such as postherpetic neuralgia (PHN). This extremely painful condition can persist for months or years, causing itching and numbness near the site of the shingles even after the blisters have healed.
"Risk increased markedly with age, with those older than 64 years having more than six times the risk of complications of those younger than 25 years," reported senior investigator of both reports, Dr. Richard Platt, of the Brigham and Women's Hospital and Harvard Medical School in Boston. Shingles occurs when chickenpox virus, or varicella, which can lie dormant inside the central nervous system, escapes immune system surveillance and becomes reactivated.
In the new study of 859 people with shingles, 101 developed complications such as infections, eye or ear involvement, nerve inflammation, or meningitis -- inflammation of the membrane covering the brain. The most common complication was PHN, which occurred in 8% of patients.
In the second study, the same group of researchers took a closer look at risk factors for postherpetic neuralgia, and found that those over age 50 had more than 14 times the risk of developing PHN within one month and 27 times the risk of developing PHN by two months compared with their younger counterparts.
The study also found that a drugs commonly used to treat shingles, including corticosteroids and antiviral drugs, don't help relieve those with PHN, noted Drs. Rhonda Kost and Stephen Straus in an editorial accompanying the studies.
"The antiviral agents acyclovir, famciclovir, and valacyclovir hydrochloride limit viral replication, accelerate healing, and reduce early pain, and the newer agents famciclovir and valacyclovir may accelerate the resolution of chronic pain, but neither they nor acyclovir reduce the likelihood of PHN at six months after onset of rash," wrote Kost and Straus, of the National Institute of Allergy and Infectious Diseases in Bethesda, Maryland.
Some studies have suggested -- though not conclusively proven -- that vaccinating adults for chickenpox can help reduce PHN if shingles should arise.
"Until we can reverse the consequences of aging of the nervous system, the best prevention of PHN may be the prevention of zoster itself," the authors wrote.
SOURCE: Archives of Internal Medicine (1997;157:1209-1213, 1217-1224, 1166-1167)
