SUMMARY:

Herpes zoster, more commonly known as shingles, is caused by a virus that establishes latency on dorsal root and cranial nerve ganglia after a varicella-zoster (chickenpox) infection. Eventual reactivation of the virus causes it to spread from a nerve root to a cutaneous dermatome and produce a characteristic painful rash. The incidence of herpes zoster increases with age, which is why the rash usually presents in elderly populations, with a median age of 64.

• Clinical presentation
• Differential diagnosis
• Complications
• Treatment

Clinical Presentation

• Painful prodrome typically precedes rash by 2 to 3 days
• Pain can be constant or intermittent—usually described as a “burning” or “throbbing”
• Rash manifests as erythema and macules, followed by papules
  • Papules develop into vesicles in 1 to 2 days
  • Vesicle formation continues for 3 to 4 days
  • All types of lesions (erythema, macules, papules, vesicles) may be present at 1 week
• Lesions tend to cluster at cutaneous nerve branches
• Only a single dermatome is typically affected in immunocompetent patients

Differential Diagnosis

• Can be confused with zosteriform herpes simplex and contact dermatitis
• Diagnostic tests such as PCR and immunohistochemical analysis of a skin scraping can be used to confirm diagnosis

Complications of Herpes Zoster

• Mostly limited to immunocompromised populations (e.g. AIDS, chemotherapy)
  • Encephalitis
  • Herpes zoster ophthalmicus with delayed contralateral hemiparesis
  • VZV retinitis
  • Myelitis
  • Persistent pain (postherpetic neuralgia)

Treatment

Antiviral Therapy Shortens Duration of Rash and Viral Shedding

• Acyclovir: 800 mg 5 times daily for 7 to 10 days
• Famciclovir: 500 mg 3 times daily for 7 days
• Valacyclovir: 1000 mg 3 times daily for days

Acute Pain

• Treat acute pain with OTC analgesics: Acetaminophen or NSAIDs
  • Keep lesions clean and dry
• If OTCs fails, consider longer term pain management
  • Gabapentin: Start with 100 mg capsule twice a day and titrate up 300 mg 3 times a day
  • Pregabalin: 75 mg daily titrated up to 300 mg in 3 divided doses
  • Nortriptyline: 10 mg and titrate up to 40 mg nightly
• There is no indication for systemic glucocorticoids
• Therapy during the acute phase does not prevent postherpetic neuralgia
• Lesions may take 2 to 4 weeks to heal

Secondary Bacterial Infections

• Treat with systemic antibiotics to cover staph and strep (such as cephalosporin)

Additional Considerations

• Transmission Risk
  • Patients with active lesions can transmit VZV to persons who have not had varicella infection, varicella-zoster vaccination or immunocompromise patients
  • Pregnant women who do not have adequate varicella titers are also at higher risk
  • Patients are considered contagious until all lesions have crusted over
• Varicella Vaccination
  • Adults who do not have antibodies to varicella should receive 2 doses of varicella vaccine 1 to 2 months apart
  • Exceptions: Pregnant woman or women planning pregnancy

Learn More – Primary Sources:

IDSA: Recommendations for the treatment of herpes zoster, Clinical Infectious Diseases 2007

AAFP: Herpes Zoster and Postherpetic Neuralgia: Prevention and Management

CDC: Shingles (Herpes Zoster)