Shingles

Definition

Shingles is infection by the varicella-zoster virus of the dorsal root ganglia of the spine. Equivalent terms for shingles are herpes zoster, zoster, zona, or acute posterior ganglionitis.

Description

Shingles is an infection of the central nervous system, in particular, the dorsal root ganglia of the spine, which migrates through sensory nerves to the skin. There it manifests (usually on the upper trunk) as painful, bumpy, fluid-filled eruptions or vesicles. Shingles may also cause nerve pain (neuralgia). The affected areas of skin are those supplied by sensory nerves radiating from the infected dorsal root ganglia. Sensory nerves from these ganglia serve non-overlapping, sharply bounded strips or areas of the skin called dermatomes. Because the left and right sides of the body are divided into separate sets of dermatomes, shingles lesions do not cross the midline of the body.

Demographics

The virus that causes shingles is usually contracted in childhood. It is the same virus that causes chicken pox, which is primarily a disease of childhood because it is highly contagious; that is, few individuals live to adulthood without contracting chicken pox. (This statement applies to the temperate zones of the world. For unknown reasons, chicken pox and shingles are less prevalent in tropical regions.) The virus that causes both chicken pox and shingles can, however, be contracted by an individual for the first time in adulthood. First infection, at whatever age it occurs, is called primary infection. Primary infection does not cause shingles; shingles arises from reactivation of virus introduced to the body by an earlier, primary infection.

Shingles arises in individuals who have already had chicken pox, and especially in people with weakened immune systems, such as the elderly or people receiving chemotherapy or bone marrow transplantation. Persons with AIDS are also vulnerable to shingles. Shingles incidence increases steadily with age. Among 10–19 year olds, the rate per 1,000 persons per year is only 1.38. In the 30–49 age range, it rises to 2.29 cases of shingles per 1,000 persons per year. By age 60–79, almost seven cases occur per 1,000 people per year, and this increases to 10 in the 80–89 age group.

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Author Info: Larry Gilman PhD, The Gale Group Inc., Gale, Detroit, Gale Encyclopedia of Neurological Disorders, 2005

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