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The Risk Factors for Shingles

by Contributing Writer

Overview

The varicella zoster virus remains dormant in the nerve cells long after a chicken pox infection resolves. In some people who have had chicken pox, the virus can become reactivated, causing herpes zoster, or "shingles." Various factors predispose an individual to develop shingles. In 2006, the U.S. Food and Drug Administration approved a vaccine designed to prevent the disease and its potentially significant complications, particularly in those at risk for shingles.
What is Shingles?

The initial infection with varicella zoster causes chicken pox, a common contagious childhood illness that causes an itchy skin rash characterized by pockmarks and open sores. After chicken pox resolves, the virus continues to live dormant in the dorsal root and cranial nerve ganglia of the nervous system. Years or even decades later, the varicella zoster virus can become reactivated. The virus replicates and spreads from the ganglia to neural tissue and the dermatome, the area of skin innervated by the affected nerve. When reactivated, the virus causes shingles, with symptoms distinctly different from chicken pox.

Incidence

According to the Advisory Committee on Immunization Practices, one in three persons in the general U.S. population will develop shingles, and approximately one million new cases of shingles occur annually.
Symptoms

Shingles is characterized by a localized, unilateral, painful and often blistering skin rash. The blisters usually scab within three to five days, and the pain typically lasts two to four weeks. The pain is unique, described as continuous burning or aching pain, periodic piercing pain or electric shock. Other symptoms include fever, headache, chills and nausea.
Complications

The most common complication of shingles, occurring in approximately one in five patients, is post-herpetic neuralgia, a chronic pain condition where the pain continues over a month after the onset of shingles and after the rash and blisters resolve. Allodynia, another complication and similar to PHN, is characterized by pain caused by very little stimulation, such as the slightest touch, a brush of clothing or even a breeze. Other complications include bacterial skin infection, facial paralysis, Guillain-Barre syndrome, encephalitis and death.
Risk Factors

Only people who have had chicken pox, or received the chicken pox vaccine, can develop shingles. Shingles is more common in adults than in children. People who are age 50 or older, who are immunocompromised, such as with HIV or cancer, who are under immunosuppressive therapy for cancer chemotherapy or after organ transplantation or have other medical conditions preventing proper immune function are at particular risk for shingles.
Prevention

Although a vaccine for chicken pox has been available since 1995, a vaccine for shingles was first FDA-approved in 2006. The shingles vaccine is available for individuals age 60 or older. The vaccine is not recommended for individuals allergic to gelatin or neoymycin, who have a disease weakening the immune system, who are taking high doses of steroids, who have active tuberculosis not under treatment or who are pregnant or may be pregnant.