Varicella-Zoster Virus (VZV)

Updated: Aug 08, 2017
  • Author: Wayne E Anderson, DO, FAHS, FAAN; Chief Editor: Pranatharthi Haran Chandrasekar, MBBS, MD  more...
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Overview

Practice Essentials

Varicella-zoster virus (VZV) causes chickenpox and herpes zoster (shingles). Chickenpox follows initial exposure to the virus and is typically a relatively mild, self-limited childhood illness with a characteristic exanthem, but can become disseminated in immunocompromised children. Reactivation of the dormant virus results in the characteristic painful dermatomal rash of herpes zoster, which is often followed by pain in the distribution of the rash (postherpetic neuralgia). See the image below.

Typical zoster in the vicinity of right popliteal Typical zoster in the vicinity of right popliteal fossa in a vertebral nerve L4 distribution.

Signs and symptoms

Pain and paresthesia are typically the first symptoms of VZV infection. Until the characteristic vesicular rash erupts, diagnosis may be difficult. A prodromal period during which symptoms may vary is common. Pain occurs in 41% of patients, itching in 27%, and paresthesias in 12%.

During the acute illness, patients may experience the following:

  • Pain (90%)
  • Helplessness and depression (20%)
  • Flulike symptoms (12%)

Herpes zoster (shingles)

  • The most common presentation is the shingles vesicular rash, which most commonly affects a thoracic dermatome
  • After a prodromal illness of pain and paresthesias, erythematous macules and papules develop and progress to vesicles within 24 hours
  • The vesicles eventually crust and resolve
  • Pain and sensory loss are the usual symptoms
  • Motor weakness also occurs and is frequently missed on examination
  • Cases of actual monoplegia due to VZV brachial plexus neuritis have been reported

Zoster multiplex

  • Shingles may appear in multiple dermatomes, both contiguous and noncontiguous, on either side of the body
  • Immunocompromised individuals are more susceptible
  • Terminology depends on the number of involved dermatomes and on whether the condition is unilateral or bilateral (eg, zoster duplex unilateralis refers to the involvement of 2 unilateral dermatomes)
  • Cases of zoster simultaneously occurring in 7 noncontiguous dermatomes have been reported

Zoster sine herpete

VZV infection may reactivate without causing cutaneous vesicles. These patients have severe dermatomal pain, possible motor weakness and possible hypesthesia, but no visible rash or vesicles.

VZV infection may present as acute peripheral facial palsy in 8-25% of patients who have no cutaneous vesicles. This is more common in immunosuppressed patients who use acyclovir (or other agents) as zoster prophylaxis. [1]

Central nervous system deficits

  • More common in immunocompromised individuals, but do occur in the general population
  • CNS involvement may become apparent 3 weeks after the onset of the initial rash
  • The manifestations are usually bilateral
  • The physical findings may progress
  • The underlying pathology typically progresses for 3 or more weeks
  • Progression for 6 months in immunocompromised individuals has been reported
  • Recurrence is rare but has been reported
  • Zoster encephalitis is also rare but is reported in otherwise healthy individuals

Ramsay-Hunt syndrome

This syndrome occurs when the geniculate ganglion is involved. The clinical presentation includes the following:

  • A peripheral facial palsy
  • Pain in the ear and face
  • Vesicles in the external ear canal (not always present)
  • Additional auditory and vestibular symptoms in some cases

Keratitis (herpes ophthalmicus)

  • Caused by reactivation of VZV infection in the ophthalmic division of the trigeminal nerve.
  • The presentation may include conjunctivitis or corneal ulcers
  • Complications include blindness
  • Vesicles do not have to be present
  • Rarely, the virus migrates along the intracranial branches of the trigeminal nerve, causing thrombotic cerebrovasculopathy with severe headache and hemiplegia

See Clinical Presentation for more detail.

Diagnosis

When the presentation includes the typical dermatomal rash, additional studies are not required. Studies to consider in specific situations include the following:

  • If the diagnosis is in doubt, a Tzanck smear or culture of vesicular fluid can be performed
  • In cases of zoster sine herpete, DNA analysis via PCR can be used
  • In cases of acyclovir-resistant VZV, detections of mutations in thymidine kinase can be determined by PCR and sequence analysis
  • MRI may be useful if myelitis or encephalitis is suspected
  • Lumbar puncture may be helpful if signs suggest myelitis or encephalitis

See Workup for more detail.

Management

Treatment options are based on the following:

  • Patient age
  • Patient immune state
  • Duration of symptoms
  • Presentation

Antiviral medications decrease the duration of symptoms and the likelihood of postherpetic neuralgia, especially when initiated within 2 days of the onset of rash. Oral acyclovir may be prescribed in otherwise healthy patients who have typical cases. Compared with oral acyclovir, other medications (eg, valacyclovir, penciclovir, famciclovir) may decrease the duration of the patient's pain.

Varicella zoster immune globulin (VariZIG) is indicated for administration to high-risk individuals within 10 days (ideally within 4 days) of chickenpox (VZV) exposure. [2] High- risk groups include the following:

  • Immunocompromised children and adults
  • Newborns of mothers with varicella shortly before or after delivery
  • Premature infants
  • Infants less than younger than 1 year of age
  • Adults without evidence of immunity
  • Pregnant women

See Treatment and Medication for more detail.

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Background

Varicella-zoster virus (VZV) is the cause of chickenpox and herpes zoster (also called shingles). Chickenpox follows initial exposure to the virus and is typically a relatively mild, self-limited childhood illness with a characteristic exanthem.

Approximately 1 per 4000 children develops VZV encephalitis, an acute neurologic disorder with potentially severe complications. In addition, immunocompromised children (eg, those receiving chemotherapy for leukemia or those with advanced HIV infection) can develop disseminated VZV infection, a potentially fatal complication.

After primary infection, VZV remains dormant in sensory nerve roots for life. Upon reactivation, the virus migrates down the sensory nerve to the skin, causing the characteristic painful dermatomal rash. After resolution, many individuals continue to experience pain in the distribution of the rash (postherpetic neuralgia). In addition, reactivation of VZV infection can cause a spectrum of atypical presentations, ranging from self-limited radicular pain without rash to spinal cord disease with weakness.

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Pathophysiology

The host immunologic mechanisms suppress replication of the virus. Reactivation can occur if host immune mechanisms are compromised. This may be caused by medications, illness, malnutrition, or by the natural decline in immune function with aging. Upon reactivation, the virus migrates along sensory nerves and produces sensory loss, pain, and other neurologic complications. If motor nerve roots are also involved, weakness can develop in addition to sensory changes. Leptomeningeal involvement is rare but may develop when the ophthalmic branch of the trigeminal nerve is involved.

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Frequency

United States

The rate of occurrence is about 5 persons per 1000 population. Immunosuppression increases this risk. The risk of postherpetic neuralgia increases with age. Approximately 50% of patients older than 60 years may have temporary or prolonged pain syndrome.

The frequency of VZV infection may decrease as the immunized children become adults.

International

VZV infection occurs with the same frequency in the United States and internationally.

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Mortality/Morbidity

Severe pain and insomnia are most bothersome to patients. About 95% of patients with zoster experience severe pain during the illness.

Other presentations of zoster, including ocular (keratitis) and spinal cord (myelitis) presentations, may result in additional morbidity.

Bacterial superinfection (impetiginization) of vesicular skin lesions can occur.

Race

The vesicular eruption of VZV infection may be more difficult to diagnose in patients with darker skin.

Sex

VZV infection occurs with equal frequency in males and females.

Age

After primary infection, zoster can occur at any age. However, the risk of zoster increases with age.

The risk of postherpetic neuralgia also increases with advancing age.

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