Also called: Herpes zoster, Postherpetic neuralgia
Introduction
When the itchy red spots of childhood Chickenpox* disappear and life returns to normal, the battle with the virus that causes chickenpox seems won. But for too many of us this triumph of Immune system over virus is temporary. The virus has not been destroyed but remains dormant in our nerve cells, ready to strike again later in life. This second eruption of the chickenpox virus is the disease called Shingles or herpes-zoster .
"I was having exams at college and I got a rash in a band around one side of my waist. The spots were very painful. At first I thought it was chickenpox, but I'd had that years before," recalls a young woman who had shingles in her twenties.
The young woman's memory was {mosgoogle right}correct. She did have chickenpox as a child. You cannot develop shingles unless you have had an earlier exposure to chickenpox, and most people who get chickenpox are at risk for shingles. The woman had the typical one-sided band of rash and Pain of this common neurological disorder. Her age was unusual, however.
While young people do develop shingles, the disease most often strikes after age 40. But since shingles is so common, affecting an estimated one-quarter of Americans at some point during their lifetimes, cases in young people are not rare.
What is Shingles?
Scientists call the virus that causes chickenpox/shingles varicella-zoster virus or VZV. The word "varicella" is derived from "variola," the Latin word for Smallpox, another infectious disease that can resemble chickenpox. (Smallpox is a highly contagious and often fatal disease that has disfigured or killed millions of people, especially during the Middle Ages.) “Zoster” is the Greek word for girdle; shingles often produces a girdle or belt of blisters or lesions around one side of the waist. This striking pattern also underlies the condition's common name: shingles comes from “cingulum,” the Latin word for belt or girdle.
VZV belongs to a group of viruses called herpesviruses. This group includes the Herpes Simplex virus that causes Cold sores, Fever blisters, Mononucleosis, Genital Herpes (a sexually transmitted disease), and Epstein-Barr virus involved in Infectious Mononucleosis. Like VZV, other herpesviruses can hide in the nervous system after an initial Infection and then travel down nerve cell fibers to cause a renewed infection. Repeated episodes of cold sores on the lips are the most common example.
As early as 1909, scientists suspected that the viruses causing chickenpox and shingles were one and the same. In the 1920s and 1930s, the case was strengthened by an experiment in which children were inoculated with fluid from shingles blisters. Within 2 weeks, about half of the children developed chickenpox. Finally, in 1958, detailed analyses of the viruses taken from patients with either chickenpox or shingles confirmed that the viruses were identical.
Virtually all adults in the United States have had chickenpox, even if it was so mild as to pass unnoticed, and thus may develop shingles later in life. In the original exposure to VZV (chickenpox), some of the virus particles leave the blood and settle into clusters of nerve cells (neurons ) called sensory ganglia, where they remain for many years in an inactive (latent) form. The sensory ganglia, which are adjacent to the Spinal cord and brain, relay information to the brain about what the body is sensing - heat, cold, touch, pain.
When the VZV reactivates, it spreads down the long nerve fibers (axons) that extend from the sensory cell bodies to the skin. The viruses multiply, the telltale rash erupts, and the person now has herpes-zoster, or shingles. With shingles, the nervous system is more deeply involved than it was during the bout with chickenpox, and the symptoms are often more complex and severe.
