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Shingles

What is it?

Shingles, also known as Herpes Zoster, is a painful rash caused by the varicella-zoster virus, the same virus that causes chicken pox. Varicella-zoster is a member of the Herpesvirus family, which includes Herpes Simplex 1 and 2, Epstein-Barr virus (which causes mononucleosis), and the virus which causes roseola (“sixth disease”), a common childhood illness, among others. These viruses are capable of causing lifelong infections. After the primary infection (in the case of varicella-zoster, “chicken pox”), the herpesvirus becomes latent in nerve cells. The latent virus produces no symptoms. Reactivation of the virus may occur at a later time, producing different symptoms. Reactivation of varicella-zoster produces “shingles” (or “zona”).

When the virus reactivates, it causes painful blisters on the area of skin supplied by the nerve (the “dermatome”).This rash is almost always on one side of the body and in a stripe pattern.  Burning, itching, or tingling sensations often precede the rash. The rash usually heals in 2-4 weeks, but in some persons residual nerve pain (“postherpetic neuralgia”) may continue for months or years. Both shingles and postherpetic neuralgia are much more common in persons over 50 and immunocompromised persons. Shingles is more common in females. The CDC estimates that 32% of the US population will experience shingles in their lifetime. Approximately 1-4% of persons will experience a second episode. Although chicken pox is less common since the development of varicella vaccine, the incidence of shingles has not decreased. In fact, it has increased slightly.

Medications & Treatment

Antiviral medications (acyclovir, famciclovir, or valacyclovir) may decrease the pain and shorten the duration of the rash and there is some evidence they decrease the likelihood of postherpetic neuralgia. Treatment should begin within 48-72 hours after rash appears. The benefit of these medications in people younger than 50 is not as clear. Shingles on the face or ear require immediate evaluation and treatment. In about two percent of cases, blisters become infected with skin bacteria. If increased redness, swelling, pain, warmth, or pus around the rash occurs or fever, nausea, headache, or body aches is experienced, care should be sought promptly.

Transmission

Although shingles cannot be transmitted to others, contact with the rash or liquid from the blisters will cause chicken pox in those who have not had the disease or the vaccine.

Reference

Albrecht M. Epidemiology and pathogenesis of varicella-zoster virus infection: Herpes zoster. UpToDate (17.3). July 2009.
http://en.wikipedia.org/wiki/Herpes_zoster
http://en.wikipedia.org/wiki/Herpesviridae