AUTHOR AND EDITOR INFORMATION

Section 1 of 11  

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• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
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INTRODUCTION

Section 2 of 11  

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Background

Herpes zoster presents in many ways. It should not be considered simply a self-limited dermatomal rash with pain. Varicella-zoster virus (VZV) infection is an acute neurologic disease that warrants immediate evaluation. A common misperception is that VZV always is a benign disorder.

Following initial infection, usually as chickenpox in childhood, VZV remains dormant in the dorsal spinal root ganglion neurons and the fifth cranial nerve ganglion neurons. Upon reactivation, a spectrum of signs and symptoms can occur, including a self-limited painful rash, pain without skin manifestations, keratitis, vertigo, and spinal cord disease with weakness. Once VZV infection resolves, many individuals continue to suffer pain, a condition known as postherpetic neuralgia (PHN).

Pathophysiology

VZV remains latent in the dorsal root ganglia after an initial infection (chickenpox). Host immunologic mechanisms suppress replication of the virus, but VZV reactivates when the host mechanisms fail to contain the virus. This occurs from a wide spectrum of issues, from stress to severe immunosuppression. Occasionally this follows direct trauma. VZV viremia occurs frequently with chickenpox but also may occur with herpes zoster, albeit with a lower viral load. The virus migrates from the sensory root and produces a dermatomal sensory loss and a characteristic painful rash.

Inflammatory involvement may include the leptomeninges. When the cervical and lumbar roots are involved, motor involvement (which often is overlooked) may be seen, depending on the virulence and/or extent of migration.

VZV is a DNA virus. The viral genome encodes approximately 70 proteins. Once activated at the spinal root or cranial nerve neurons, an inflammatory response occurs that also encompasses the leptomeninges. Both plasma cells and lymphocytes are noted. In at least one case of motor neuron involvement, lymphocytic infiltration and myelin breakdown were observed with preservation of axons.

Frequency

United States

Incidence is approximately 5 per 1000 per year. Immunosuppression increases risk. The incidence of PHN increases with age. Half of patients older than 60 years may have a temporary or prolonged pain syndrome. Although 50% or more of patients with PHN may have resolution of the pain within 1-2 years, the remainder may have a continuing pain syndrome. Fortunately newer treatments are available for PHN. 

Although the frequency of varicella zoster may decrease as the vaccinated children grow to adulthood, the present frequency of varicella zoster in adults may be increasing.

International

The international frequency is the same as for the United States.

Mortality/Morbidity

Ninety-five percent of patients with zoster experience severe pain. The acute pain and insomnia are most bothersome.

• Variant presentations of zoster (eg, keratitis, myelitis) may carry additional morbidity.
• Duration of symptoms, incidence of complications and duration of post-herpetic neuralgia if it should occur, are longer in immunocompromised patients.
• Complications may occur. For example, staphylococcal and streptococcal bacteria may superinfect the skin lesions and require treatment.

Race

Although the pathophysiology is uncertain, the vesicular eruption may be less frequent in African Americans. The reason is not clear.

Sex

• Prevalence in males and females is equal.
• Ertunc and colleagues suggested both that zoster frequency is higher in right-handed patients and that the rash appears more frequently on the left side in females.¹ The pathophysiology for these differences is uncertain.

Age

• Although zoster can occur at any age after primary infection, incidence increases with age. Also troublesome is the increasing incidence of PHN with advancing age.

CLINICAL

Section 3 of 11  

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History

During the prodromal phase, paresthesias and pain may present a diagnostic dilemma; however, the dermatomal distribution helps clarify the diagnosis.

• Goh and Khoo studied 164 patients with zoster and recorded the frequency of prodromal symptoms: 41% had pain (more common in patients older than 50 years), 27% had itching, and 12% had paresthesias.²
• Once the typical rash erupts, the diagnosis is easier, but zoster has various presentations. Goh and Khoo reported the frequency of active disease symptoms: 90% had pain, 20% had feelings of helplessness and depression, and 12% had flu-like symptoms.²
• Zoster may have atypical presentations. Cases of unilateral headache, the appearance of an ocular chemical burn, and facial palsy have been reported in the literature.

Physical

• Shingles
• • Shingles refers to the painful rash associated with reactivated VZV infection; it typically affects a single dermatome, most commonly a thoracic dermatome. After a prodromal illness, erythematous macules and papules appear and progress to vesicles within 1 day. The lesions eventually crust and resolve. Patients may experience pain and sensory loss in the distribution of the rash. Motor weakness, especially in lumbar and cervical radicular distributions, is often present but not appreciated and represents viral activity beyond the sensory root. Because the weakness often is not diagnosed accurately, the incidence and prevalence are uncertain.
  • Note that zoster may present in multiple dermatomes and possibly bilaterally (ie, zoster multiplex). The frequency of multiple, disseminated, and visceral zoster is increased in the immunocompromised population. Occasionally, patients experience paresthesias and pain in a dermatomal distribution without a rash (ie, zoster sine herpete).
• Zoster multiplex
• • Zoster occurring in noncontiguous dermatomes is rare, even in immunocompromised individuals. Terminology depends on whether the condition is unilateral or bilateral and on the number of involved dermatomes.
  • For example, zoster duplex unilateralis refers to the involvement of 2 unilateral dermatomes. Vu and colleagues report one case of zoster multiplex involving 7 noncontiguous dermatomes.
• Myelitis and encephalitis
• • Be aware of possible VZV myelitis. Devinski and colleagues report spinal cord involvement in immunosuppressed persons.³ The condition emerges as the expected dermatomal rash.
  • Spinal cord involvement becomes apparent within 2-3 weeks from the initial rash with myelopathic findings on examination. Manifestations are usually bilateral. The disease may progress for 3 weeks, although a few cases of progression for as long as 6 months have been reported in patients with AIDS. Recurrent zoster myelitis is rare, although one case has been reported of a previously healthy young woman who developed recurrent myelopathy at the same spinal level. The condition resolved fully with intravenous (IV) acyclovir treatment.
  • Rarely, VZV may cause encephalitis. Westenend and Hoppenbrouwers reported fatal hemorrhagic encephalitis in an otherwise healthy woman.⁴
  • Myelitis and encephalitis may occur in previously healthy individuals.
• Ramsay-Hunt syndrome
• • If the geniculate ganglion is involved, this syndrome of peripheral facial palsy with pain and vesicles in the ear may occur.
  • The vesicles are noted in the external ear canal or on the tympanic membrane; additional auditory and vestibular symptoms may be present.
• Keratitis
• • Ocular involvement occurs when the ophthalmic division of the trigeminal nerve is involved in the viral reactivation (see Media file 1).
  • Complications range from corneal ulcers to conjunctivitis to blindness.
  • Occasionally, no vesicles are seen (ie, zoster sine herpete).
  • Svozilkova and colleagues report one case of varicella-caused retinal necrosis after ocular trauma.⁵
• Zoster sine herpete
• • VZV reactivation may occur without cutaneous vesicles. In such cases, patients may experience pain and weakness in a dermatomal distribution but have no visible signs of shingles.
  • Furuta and coworkers noted that VZV may be demonstrated in 8-25% of patients with acute peripheral facial palsy without cutaneous vesicles.⁶
  • This condition presents a diagnostic dilemma; however, VZV DNA may be detected by polymerase chain reaction (PCR) from oropharyngeal swabs in patients with zoster peripheral facial palsy. Because such studies are not routine, the true incidence and prevalence are unknown.
• Brachial plexus neuritis
• • Fabian and colleagues reported one patient who had a left upper arm monoplegia after a C4, C5, and C6 zoster multiplex.
  • The authors believed that the brachial plexus inflammation was an extension of a dorsal ganglionitis. They found that the motor neuropathy was an inflammatory demyelinating process.

Causes

Risk of typical shingles and atypical presentations (eg, myelitis, encephalitis, disseminated disease, visceral involvement) is increased in immunosuppressed patients.

DIFFERENTIALS

Section 4 of 11  

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Other Problems to be Considered

Syphilis
Vestibular neuronitis
Malignant and nonmalignant pain syndromes
Back pain

WORKUP

Section 5 of 11  

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Lab Studies

• In cases of typical zoster special laboratory studies are unnecessary.
• In cases of zoster sine herpete, DNA analysis by PCR appears more useful than the standard assays, especially for early diagnosis.

Imaging Studies

• Magnetic resonance imaging (MRI) may be used in cases of myelopathy or encephalopathy to exclude other etiologies.
• Carreau and colleagues visualized facial nerve lesions with enhanced MRI in peripheral facial palsy.

Other Tests

• Lumbar puncture: Because the inflammatory response involves the leptomeninges, cerebrospinal fluid (CSF) may show increased protein and a pleocytosis.
• Biopsy can provide definitive diagnosis but is seldom necessary.

Histologic Findings

• VZV is a DNA virus. The viral genome encodes approximately 70 proteins. Once activated at the spinal root or cranial nerve neurons, an inflammatory response occurs that also encompasses the leptomeninges. Both plasma cells and lymphocytes are noted. In at least one case of motor neuron involvement, lymphocytic infiltration and myelin breakdown were observed with preservation of axons.

TREATMENT

Section 6 of 11  

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Medical Care

• Choices are dependent on the host immune state and the presentation of zoster. Current research considers whether the zoster vaccine may prove beneficial in the treatment of active zoster.
• • For typical zoster, oral acyclovir has been used. However, oral acyclovir has limited bioavailability, and resistant viral strains are emerging.
  • Newer medications such as penciclovir and famciclovir may have an increasing role in treatment. They may decrease the time to resolve pain compared to oral acyclovir, possibly secondary to increased bioavailability. Fewer daily dosings may improve compliance. As noted by Stein, famciclovir can affect subsequent latent infection with herpes simplex virus 1 (HSV-1).⁷ However the clinical relevance is uncertain.
• Whether treatment with antiviral medications is essential for typical zoster is a topic of debate.
• • Many studies show that antiviral medication can decrease the duration of symptoms and decrease the likelihood of PHN, especially when employed at the onset of the eruption.
  • However, Kubeyinje reports that the use of acyclovir in healthy young adults with zoster is not justified, especially in developing countries with limited resources.⁸ Forty patients with zoster who received oral acyclovir were compared to 40 patients who did not receive medication. Both groups consisted only of healthy young adults. The author reports no statistical difference in the duration of acute pain or the development of complications in this specific population. These results cannot be extrapolated to the elderly, who are at greater risk of PHN.
• Whether steroids are essential or even helpful for zoster also is debated. Some studies have provided evidence that the early use of steroids may decrease the incidence of PHN; other studies fail to show benefit.

Surgical Care

• Surgery rarely may be required for zoster complications (eg, necrotizing fasciitis).

Consultations

• Neurology - In cases with associated myelopathy or encephalopathy
• Infectious disease - For atypical cases and/or when evidence of superinfection
• Ophthalmology - In cases with eye structure involvement
• Dermatology - Helpful for diagnosis, if the rash is atypical
• Other consultants may be necessary, depending on the presentation and complications.

MEDICATION

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The decision to select a specific medication must be a clinical decision. This guide cannot substitute for medical decision making.

Drug Category: Antiviral agents

These may help reduce pain, symptoms, and incidence of PHN. All 3 medications must be used cautiously in cases of renal compromise. Hemolytic uremic syndrome is rare but reported. All 3 agents may be used for 7-10 days, depending on response. Only acyclovir is available in IV form.

Drug Name	Valacyclovir (Valtrex)
Description	Prodrug that is converted rapidly to acyclovir before exerting antiviral activity.
Adult Dose	1000 mg PO tid for 7-10 d
Pediatric Dose	Not established
Contraindications	Documented hypersensitivity
Interactions	Cimetidine, AZT (zidovudine), and probenecid can increase half-life and CNS toxicity
Pregnancy	B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions	Because medication converted to acyclovir, same precautions apply: use caution in patients with renal insufficiency or receiving other nephrotoxic drugs

Drug Name	Famciclovir (Famvir)
Description	After ingestion, drug is rapidly biotransformed into active compound penciclovir and phosphorylated by viral thymidine kinase. By competition with deoxyguanosine triphosphate, penciclovir triphosphate inhibits viral polymerase subsequently inhibiting viral DNA synthesis/replication. Adjust dose in patients with renal insufficiency or hepatic disease.
Adult Dose	500 mg PO tid for 7-10 d
Pediatric Dose	Not established
Contraindications	Documented hypersensitivity
Interactions	Probenecid or cimetidine prolongs half-life and thus may increase toxicity; increases bioavailability of digoxin
Pregnancy	B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions	Use caution when patient has renal failure or receiving other nephrotoxic drugs

Drug Category: Corticosteroids

Some authors find benefit in the short-term use of steroids. Some evidence exists to suggest a decreased incidence of PHN in patients who received steroids. Other studies find no benefit from the use of steroids. This author does not begin steroids in typical zoster cases.

Drug Category: Vaccines

Elicit active immunization to increase resistance to infection. Vaccines consist of attenuated microorganisms or cellular components, which act as antigens. Administration stimulates antibody production with specific protective properties.

FOLLOW-UP

Section 8 of 11  

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Further Inpatient Care

• A study by Morgan and King⁹ showed that the eye was the most common site of zoster involvement in patients requiring hospital admission.
• • Pain was the main complaint.
  • Inpatient treatment is appropriate for the immunocompromised or those with atypical presentations, including myelitis.

Further Outpatient Care

• Typical cases of zoster may be treated in the outpatient setting. Initial evaluation should address the possibility of atypical manifestations.

Deterrence/Prevention

• Some studies suggest that varicella immunization may protect against future episodes.
• The varicella vaccine may stimulate immunity in seropositive adults, suggesting that the vaccine may constitute treatment and perhaps prevention of zoster (even with previous exposure to chickenpox).
• However, the patient should be informed that both clinical varicella and zoster may follow the vaccine.

Complications

• In cases of typical dermatomal zoster, superinfection with streptococci or staphylococci commonly occurs.
• Ocular, spinal cord, or other involvement carries a risk of permanent injury, although the myelitis tends to resolve.
• Galil et al noted that trigeminal distribution and/or advanced age increase the risk of complications.¹⁰
• With ocular involvement, long-term antiviral treatment may be required.
• Dermatologic superinfection may occur. Necrotizing fasciitis is another possible complication.
• Vasculopathy is a potentially serious complication of reactivation of VZV.
• Hong and Elgart have reported gastrointestinal complications.¹¹
• Westenend and Hoppenbrouwers have reported fatal hemorrhagic encephalitis in an otherwise healthy female.⁴
• Motor involvement is not uncommon.
• PHN is the most common complication, affecting as many as 50% of patients older than 60 years. The underlying pathophysiology of PHN may involve peripheral nerve damage or continued viral activity.

Prognosis

• PHN may persist chronically, although most cases eventually resolve. Pain probably localizes to a region of peripheral nerve damage.
• In a landmark study by Rowbotham and Fields, no clear relationship was shown between loss of peripheral nerve function and PHN pain.¹²
• • These authors stated that "preservation of several sensory modalities in their area of maximal pain suggests that, in some PHN patients, activity in primary afferent nociceptors that remain connected to both their peripheral and central targets contributes significantly to ongoing pain."
  • Although several mechanisms may be involved in pain generation, this study helped to explain the efficacy of topical agents such as capsaicin or, as noted by Rowbotham and colleagues in a different study¹³, lidocaine patches.
• As evidence of the complexity of the issue, Oaklander and coworkers found bilateral damage in cases of PHN from unilateral shingles.¹⁴ Neurite loss was noted in the contralateral homologous region in test subjects who had no pain and no shingles on that side.
• Many treatment options are available for PHN, including oral and topical medications, gamma knife procedures, and Jaipur blocks.
• Gilden and colleagues argue that PHN may result from persistent active viral activity akin to zoster sine herpete.¹⁵

Patient Education

• For excellent patient education resources, visit eMedicine's Bacterial and Viral Infections Center. Also, see eMedicine's patient education articles Shingles and Chickenpox.

MISCELLANEOUS

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Medical/Legal Pitfalls

• Failure to diagnose zoster may delay treatment and increase the possibility of PHN.
• Failure to reduce pain and suffering, even if opioid therapy is required, is problematic, especially with emerging evidence that adequate pain control acutely may reduce the incidence of PHN.
• Failure to treat zoster with antiviral medication may increase the likelihood of PHN.
• • One study by Kubeyinje concluded that acyclovir did not decrease acute pain duration in healthy young adults with typical zoster.⁸
  • The author also noted that, in healthy young adults, complications "were few and similar in the two groups."
• Failure to recognize keratitis, myelitis, encephalitis, and other manifestations may lead to morbidity and, rarely, death.
• Immunocompromised patients often take acyclovir prophylactically. In these patients, zoster may have an atypical presentation without a rash (ie, zoster sine herpete).

MULTIMEDIA

Section 10 of 11  

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• Multimedia
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Media file 1:  Herpes zoster in the ophthalmic (V1) distribution of the trigeminal nerve. Note the unilateral distribution of the rash and how the V1 distribution may extend to the tip of the nose. Though at risk for keratitis with zoster in this distribution, the patient had a normal ocular examination. Patient consented to picture distribution for educational use; written permission on file; contributed by JS Huff.
	View Full Size Image
Media type:  Photo

REFERENCES

Section 11 of 11

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2. Goh CL, Khoo L. A retrospective study of the clinical presentation and outcome of herpes zoster in a tertiary dermatology outpatient referral clinic. Int J Dermatol. Sep 1997;36(9):667-72. [Medline].
3. Devinsky O, Cho ES, Petito CK, Price RW. Herpes zoster myelitis. Brain. Jun 1991;114 ( Pt 3):1181-96. [Medline].
4. Westenend PJ, Hoppenbrouwers WJ. [Fatal varicella-zoster encephalitis; a rare complication of herpes zoster]. Ned Tijdschr Geneeskd. Mar 21 1998;142(12):654-7. [Medline].
5. Svozilkova P, Rihova E, Diblik P, et al. Varicella zoster virus acute retinal necrosis following eye contusion: case report. Virol J. Aug 31 2005;2:77. [Medline].
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21. Feder HM, LaRussa P, Steinberg S, Gershon AA. Clinical varicella following varicella vaccination: don''t be fooled. Pediatrics. Jun 1997;99(6):897-9. [Medline].
22. Goldman GS. Universal varicella vaccination: efficacy trends and effect on herpes zoster. Int J Toxicol. Jul-Aug 2005;24(4):205-13. [Medline].
23. Liang MG, Heidelberg KA, Jacobson RM, McEvoy MT. Herpes zoster after varicella immunization. J Am Acad Dermatol. May 1998;38(5 Pt 1):761-3. [Medline].
24. Mainka C, Fuss B, Geiger H, et al. Characterization of viremia at different stages of varicella-zoster virus infection. J Med Virol. Sep 1998;56(1):91-8. [Medline].
25. Makeham TP, Croxson GR, Coulson S. Infective causes of facial nerve paralysis. Otol Neurotol. Jan 2007;28(1):100-3. [Medline].
26. Sawyer AR, Williams G. Misdiagnosis of burns: herpes zoster ophthalmicus. J Burn Care Res. Nov-Dec 2006;27(6):914-6. [Medline].
27. Sjaastad O, Bakketeig LS. The rare, unilateral headaches. VĂ„gĂ„ study of headache epidemiology. J Headache Pain. Jan 15 2007;[Medline].
28. Sparks L, Russell C. The new varicella vaccine: efficacy, safety, and administration. J Pediatr Nurs. Apr 1998;13(2):85-94. [Medline].
29. Vu AQ, Radonich MA, Heald PW. Herpes zoster in seven disparate dermatomes (zoster multiplex): report of a case and review of the literature. J Am Acad Dermatol. May 1999;40(5 Pt 2):868-9. [Medline].
30. Wlodaver CG, Privett T, Livengood G. The merits of varicella vaccination for varicella non-immune health care workers. J Okla State Med Assoc. Dec 1996;89(12):430-2. [Medline].
31. Yi JY, Kim TY, Shim JH, et al. Histopathological findings, viral DNA distribution and lymphocytic immunophenotypes in vesicular and papular types of herpes zoster. Acta Derm Venereol. May 1997;77(3):194-7. [Medline].

Article Last Updated: Aug 30, 2007