Herpes Zoster

Alternative names:

shingles

Definition:

An acute, localized infection with the virus Herpes varicellae, causing painful blistering eruptions.

Causes, incidence, and risk factors:

Herpes zoster, or shingles, is caused by the same virus that causes chickenpox. It occurs as a result of the virus becoming dormant (inactive) after an attack of chickenpox and re-emerging many years later. The cause of the reactivation is unknown. Usually only one attack occurs, without recurrence. If an adult is exposed to herpes zoster virus and has not had chickenpox, a severe case of chickenpox usually develops rather than shingles.

The virus resides in a dormant condition in the nerve tracts that emerge from the spine. When it is reactivated, it spreads along the nerve tract, first causing pain or a burning sensation. The typical rash appears in 2 to 3 days, after the virus has reached the skin. It consists of red patches of skin with small blisters (vesicles) that look very similar to early chickenpox. The rash maximizes over the next 3 to 5 days. Then the blisters break forming small ulcers which begin to dry and form crusts. The crusts fall off in 2 to 3 weeks, leaving behind pink healing skin.

Lesions typically appear along a single dermatome (the body area served by a single spinal nerve) and are only on one side of the body (unilateral). The trunk is most often affected, showing a rectangular belt of rash from the spine around one side of the chest to the breastbone (sternum). Lesions may also occur on the neck or face, particularly the trigeminal nerve in the face. The trigeminal has three branches: the superior which goes to the forehead, the middle which goes to the mid-face and the inferior which goes to the lower face. Which branch is involved determines where on the face the skin lesions will be. Trigeminal nerve involvement may include lesions in the mouth or eye. Eye lesions may lead to permanent blindness.

Involvement of the facial nerve may cause Ramsay Hunt syndrome with facial paralysis, hearing loss, loss of taste in half of the tongue and skin lesions around the ear and ear canal. Shingles may, on rare occasion, involve the genitalia or upper leg.

Shingles may be complicated by a condition known as post-herpetic neuralgia. This is persistence of pain in the area where the shingles occurred that may last from months to years following the initial episode. This pain can be severe enough to be incapacitating to a person, especially if they are elderly.

Herpes zoster can be contagious through direct contact in an individual who has not had chickenpox and therefore has no immunity. Herpes zoster may affect any age group but is much more common in adults over 60 years old, in children who had chickenpox before the age of one year, and in individuals who are immunocompromised. The disorder is common, with about 300,000 cases in the U.S. per year (about 2 out of every 1,000 people).

Localized shingles involving only one dermatome is typical for an outbreak of shingles. Generalized or recurrent shingles may indicate an underlying disorder with the immune system such as leukemia, Hodgkin's disease, other cancers, atopic dermatitis, or HIV infection (ARC or AIDS). Those who are immunosuppressed because of organ transplant or treatment for cancer or similar disorders may also experience the disorder. Shingles may be an early sign in persons with HIV infection that the immune system has deteriorated enough that they would now be classified as having ARC (AIDS Related Complex) or AIDS.