Herpes Zoster

Aka: Herpes Zoster, Shingles

1. See Also
   1. Postherpetic Neuralgia
   2. Herpes Zoster Ophthalmicus
2. Epidemiology
   1. Incidence: 1 Million cases in United States annually
   2. Age: Peak onset at 50-79 years old
   3. Gender predominance: Women account for 60% of cases
3. Pathophysiology
   1. Reactivation of latent virus from dorsal root Ganglion
   2. Inflammation to acute viral ID in segmental nerve
   3. Contagious to non-immune persons
      1. Avoid contact until rash heals
4. Risk Factors
   1. Age over 50 years old
   2. Altered cell-mediated immunity
      1. HIV Infection
      2. Malignancy
      3. Organ transplant status
      4. Immunosuppressant use
5. Symptoms: Prodrome
   1. Timing
      1. May be precede rash by 1-5 days
   2. Most common symptoms
      1. Fever (variably present)
      2. Headache
      3. Photophobia
      4. Paresthesias
         1. Pain within dermatome occurs first
         2. Examples: itching, burning, hyperesthesia
      5. Malaise
6. Signs: Rash
   1. Timing
      1. Develops after 48-72 hours (up to 5 days before rash)
      2. Lesions crust and heal within 2-4 weeks
   2. Distribution
      1. Follows 1-2 dermatomes and rarely crossess the mid-line
      2. Back and face are most commonly affected
   3. Characteristics
      1. Starts as erythematous, maculopapular rash
      2. Clear Vesicles develop
      3. Vessicles turn cloudy within 3-5 days
   4. Associated Findings
      1. Tender regional lymph nodes
   5. Variants: Zoster sine herpete
      1. Zoster without rash is uncommon but does occur
   6. Images
      1. 
      2. 
7. Labs: Vesicle fluid testing
   1. Zoster PCR
      1. Test Sensitivity: 95%
      2. Test Specificity: 99%
   2. Direct immunofluorescent antigen staining
      1. Test Sensitivity: 82%
      2. Test Specificity: 76%
   3. Virus Culture
      1. Test Sensitivity: 20%
      2. Test Specificity: 99%
   4. Tzanck Smear of lesion base (Multinucleated giant cells)
      1. Rarely performed now in United States
   5. References
      1. Sauerbrei (1999) J Clin Virol 14(1): 31-36
8. Differential Diagnosis
   1. Prior to rash development, early zoster can present with such severe pain that Acute Abdomen or cardiopulmonary event may be considered
9. Complications
   1. Postherpetic Neuralgia
   2. Herpes Zoster Ophthalmicus
   3. Meningitis
   4. Encephalitis
   5. Granulomatous Angiitis with contralateral Hemiplegia
   6. Cutaneous dissemination in Lymphoma (40%)
10. Management: Antivirals
    1. Relative indications for antivirals (maximal benefit)
       1. Onset within 72 hours of starting treatment
       2. Age 50 years and older
       3. More than 50 lesions
       4. Patients are likely to see benefit if still having active vessicle eruptions, even if delayed beyond the 72 hour window
    2. Oral antiviral agents
       1. Acyclovir
          1. Dose: 800 mg orally five times daily for 7-10 days
          2. Reduces healing time, pain, and rash dissemination
          3. Least expensive of all antiviral options by an order of magnitude
          4. Valacyclovir appeared more effective in over age 50
             1. (1999) Med Lett Drugs Ther 41:113-20
       2. Valacyclovir
          1. Dose: 1000 mg orally three times daily for 7 days
          2. Equivalent efficacy to Famciclovir
             1. Tyring (2000) Arch Fam Med 9:863-9
       3. Famciclovir
          1. Dose: 500 mg orally three times daily for 7 days
          2. Lesions healed faster, more brief virus shedding
          3. Reduces Postherpetic Neuralgia duration by 2 months
          4. Reference
             1. Tyring (1995) Ann Intern Med 123:89-96
11. Management: Pain Management
    1. Analgesics
       1. Mild to moderate pain
          1. Acetaminophen
          2. NSAIDs
       2. Moderate to severe pain
          1. OpioidAnalgesics
       3. Refractory pain (agents used in Postherpetic Neuralgia)
          1. Amitriptyline (Elavil)
          2. Gabapentin (Neurontin)
    2. Systemic Corticosteroids
       1. Use is controversial
       2. May be associated with increased complications
       3. May reduce acute pain, inflammation and speed up healing
       4. Does not reduce risk of Postherpetic Neuralgia
       5. References
          1. Wood (1994) N Engl J Med 330:896-900
12. Management: Special Circumstances
    1. Zoster Ophthalmicus
       1. See Herpes Zoster Ophthalmicus
    2. Immunocompromised Patient
       1. Acyclovir 10 mg/kg IV q8h 10 days
13. Prophylaxis: Varicella Immune Globulin (VZIG) Indications
    1. Immunodeficient under age 15 years
       1. Give within 72-96 hours exposure
    2. Newborn of infected mother
       1. Exposure 5 days before delivery or 2 days after
14. Prevention
    1. Avoid contact with active Shingles or Chicken Pox
    2. Consider prophylaxis if exposure in high-risk groups
    3. Varicella Vaccine routinely in children, teens, and adults
       1. May reduce risk of developing Shingles
       2. Part of routine Primary Series
    4. Herpes Zoster Vaccine (Shingles Vaccine, Zostavax)
       1. Recommended in adults over age 50 years (if not contraindicated)
15. References
    1. Berger in Goldman (2000) Cecil Medicine, p. 2130-1
    2. Habif (1996) Dermatology, p. 351-9
    3. Gnann (2002) N Engl J Med 347:340-6
    4. Fashner (2011) m Fam Physician 83(12): 1432-7