herpes zoster

The incidence of herpes zoster increases with age. Management includes antiviral therapy (recommended in persons with or at increased risk for complications, immunocompromised persons, those ≥50 years of age, and those with severe pain or severe rash) and pain medications. The newest article in our Clinical Practice series comes from Dr. Jeffrey Cohen of the National Institutes of Health.
Primary infection with varicella-zoster virus (VZV) results in chickenpox, characterized by viremia with a diffuse rash and seeding of multiple sensory ganglia, where the virus establishes lifelong latency. Herpes zoster is caused by reactivation of latent VZV in cranial-nerve or dorsal-root ganglia, with spread of the virus along the sensory nerve to the dermatome.
Clinical Pearls
• How common is herpes zoster in the United States?
There are more than 1 million cases of herpes zoster in the United States each year, with an annual rate of 3 to 4 cases per 1000 persons. Studies suggest that the incidence of herpes zoster is increasing. Unvaccinated persons who live to age 85 have a 50% chance of developing herpes zoster.
• What is the typical clinical presentation of VZV in an immunocompetent host?
The rash of herpes zoster is dermatomal and does not cross the midline, consistent with reactivation from dorsal-root or cranial-nerve ganglia. The thoracic, trigeminal, lumbar, and cervical dermatomes are the most frequent sites of rash, although any area of the skin can be involved. In nonimmunocompromised persons, a few scattered lesions outside the affected dermatome are not unexpected. The rash is often preceded by tingling, itching, or pain (or a combination of these) for 2 to 3 days, which can be continuous or episodic. Depending upon the location and severity, this prodromal pain may lead to misdiagnosis and costly testing. The rash begins as macules and papules which evolve into vesicles and then pustules. New lesions appear over 3 to 5 days, often with filling in of the dermatome despite antiviral treatment. The rash usually dries with crusting in 7 to 10 days.
Morning Report Questions
Q: What are the indications for antiviral treatment for patients with herpes zoster, and which medications are approved for this purpose?
A: The indications for antiviral treatment in VZV are age over 50 years, moderate or severe pain, severe rash, involvement of the face or eye, zoster-related complications, and an immunocompromised state. Other persons might also benefit from antiviral therapy, although their risk of complications from zoster is lower. Three guanosine analogs — acyclovir, valacyclovir, and famciclovir — have been licensed by the Food and Drug Administration (FDA) for treatment of herpes zoster. Oral bioavailability and levels of antiviral drug activity in the blood are higher and more reliable in those receiving thrice-daily valacyclovir or famciclovir than for acyclovir 5 times daily. These antivirals hasten resolution of lesions, reduce new lesion formation, reduce virus shedding, and decrease severity of acute pain.
Table 2. Indications for Antiviral Treatment in Patients with Herpes Zoster.
Table 1. Selected Complications of Herpes Zoster in Nonimmunocompromised Persons.
Q: Who should receive herpes zoster vaccination? And for whom is it contraindicated?
A: A live attenuated zoster vaccine is recommended by the Advisory Committee on Immunization Practices in persons age 60 and older to prevent herpes zoster and its complications, including post-herpetic neuralgia. Based on the results of a recent clinical trial, the vaccine is now approved by the FDA for use in persons age 50 or above to prevent herpes zoster. A follow-up study showed that the reduction in the risk of herpes zoster remained significant for at least 5 years after vaccination, though vaccine effectiveness declined over time. Among vaccinated (as compared with unvaccinated) persons who develop herpes zoster, pain was significantly shorter in duration and less severe. The vaccine can be given to persons with a prior history of herpes zoster. The vaccine is contraindicated in persons with hematologic malignancies whose disease is not in remission or have received cytotoxic chemotherapy within 3 months, in persons with T-cell immunodeficiency (e.g., HIV infection with CD4 count less than or equal to 200/mm(3) or <15% of total lymphocytes), and in those receiving high-dose immunosuppressive therapy (e.g., greater than or equal to 20 mg of prednisone daily for greater than or equal to 2 weeks or anti-tumor necrosis factor therapy).

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