Updated: May 1, 2009
Herpes zoster (shingles) is 1 of 2 distinctive manifestations of human infection with the varicella-zoster virus (VZV), the other being varicella (chickenpox). Chickenpox is the primary infection, whereas herpes zoster represents reactivation of a previous infection. Herpes zoster has been known since ancient times and, in fact, still carries the name used by Hippocrates. Understanding the connection between herpes zoster, chickenpox, and VZV, however, is the product of more recent research done in the 19th and 20th centuries.
Chickenpox is a common and generally benign illness of childhood that is characterized by an exanthematous vesicular rash. Following resolution of this primary infection, VZV becomes latent in dorsal root ganglia until such time as a decrease in cellular immunity triggers the reactivation of the virus.
Herpes zoster typically manifests as a vesicular rash in a unilateral dermatomal distribution associated with pain. Without treatment, symptoms usually resolve over several weeks to a month. However, up to 20% of patients may experience prolonged and sometimes debilitating sequelae, chiefly postherpetic neuralgia.
VZV is an enveloped double-stranded DNA virus belonging to the Herpesviridae family. In humans, primary infection with VZV occurs when the virus comes into contact with the mucosa of the respiratory tract or conjunctiva. From these sites, it is distributed throughout the body via mononuclear cells in the blood stream. In tissue, VZV spreads from cell to cell via direct contact to produce its effects.
After primary infection, the virus migrates along sensory nerve fibers to the satellite cells of dorsal root ganglia where it becomes dormant. This dormancy may be permanent, or the virus may become reactivated by conditions of decreased cellular immunity, resulting in herpes zoster.
Prior to the advent of widespread vaccination, an estimated 4 million cases of primary VZV infection occurred annually in the United States alone. Infection was nearly universal by the end of the teenaged years, with studies showing less than 5% of adults aged 20-29 years remaining susceptible to infection. Cumulative over a lifetime, 15-30% of those with primary infections went on to experience episodes of herpes zoster. High-risk groups, such as elderly populations and immunocompromised people, might experience cumulative incidences as great as 50%. Estimated annual incidence of herpes zoster in the United States was at least 500,000 cases.
In 1995, a vaccine to prevent VZV infection was licensed in the United States and was thereafter added to the schedule of routine childhood vaccinations in the United States, as well in many other countries. Since the introduction of widespread vaccination, the incidence of primary infection has been reduced in certain populations by as much as 90%. However, the effect of childhood vaccination on the incidence of herpes zoster has yet to be adequately quantified. So far, various studies and surveillance data have failed to indicate any consistent trend in incidence rates.
Further complicating the issue of zoster frequency is the recently licensed (2006) adult vaccine (Zostavax) to prevent herpes zoster. A major study in adults aged 60 years and older demonstrated that a single dose of this vaccine reduced the incidence of herpes zoster by 51.3% over a median 3-year surveillance period compared with placebo.1 However, the effects of this vaccine on herpes zoster in the general population have yet to be quantified.
No accurate data are available, but incidence likely is similar to that in the United States.
Herpes zoster rarely causes fatalities in patients who are immunocompetent, but it can be life threatening in immunocompromised patients.
No clear predominance exists among any race or ethnic group.
No significant sex predominance has been observed in herpes zoster.
People of all ages can be affected, but incidence increases with age, presumably through the general decrease in immune function that occurs with aging. The following data are the incidence rates from 1996:
The clinical manifestations of herpes zoster can be divided into the pre-eruptive phase (preherpetic neuralgia), acute eruptive phase, and chronic phase (postherpetic neuralgia).
Presentation with a characteristic rash facilitates making the diagnosis of herpes zoster. Other findings can include lymphadenopathy and sensory changes.
Herpes Simplex
Impetigo
Smallpox
Atopic dermatitis
Atypical measles
Poison ivy
Acute herpes zoster
As described above, episodes of herpes zoster are generally self-limited and resolve without intervention. However, effective treatments do exist and can reduce the extent and duration of symptoms as well as the risk of chronic sequelae (ie, postherpetic neuralgia). Treatment is of most benefit in those patient populations at risk for prolonged or severe symptoms, specifically immunocompromised people and those older than 50 years. The benefit of treating younger and healthier populations is unclear.
Chronic herpes zoster (postherpetic neuralgia)
Primary treatments for postherpetic neuralgia include neuroactive agents such as tricyclic antidepressants, anticonvulsant agents such as gabapentin, and narcotic and nonnarcotic analgesics. No standard treatment plans or protocols exist for treating the pain associated with postherpetic neuralgia. Consultation with pain specialists may be required. Sample medications for treatment of postherpetic neuralgia are described below.
Surgical care is not generally indicated for treatment of herpes zoster. In cases of extreme intractable pain, rhizotomy (surgical separation of pain fibers) may be considered.
No specific dietary changes are recommended.
As stated above, the goals of drug therapy are to reduce the pain and other symptoms of herpes zoster episodes, and if possible, help to shorten the duration, prevent recurrence, and lower the risk of chronic sequelae.
Reduce pain and time to lesion resolution during the acute phase of shingles and may reduce risk or duration of postherpetic neuralgia.
Synthetic purine nucleoside analogue with inhibitory activity against HSV types 1 and 2 and VZV.
Adjust dosage in patients with renal insufficiency.
800 mg PO 5 times/d for 7-10 d
500 mg/m2 IV or 10 mg/kg IV q8h for 7 d
Immunocompromised children:
250-600 mg/m2 PO 4-5 times/d for 7-10 d
500 mg/m2 IV or 7.5-10.0 mg/kg IV q8h for 7 d
Concomitant use of probenecid or zidovudine prolongs half-life and increases CNS toxicity of acyclovir
Documented hypersensitivity
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Exercise caution in renal failure or when using nephrotoxic drugs
Prodrug rapidly converted to the active drug acyclovir. More expensive but has a more convenient dosing regimen than acyclovir.
1000 mg PO tid for 7 d
Not established
Probenecid, zidovudine, or cimetidine coadministration prolongs half-life and increases CNS toxicity of valacyclovir
Documented hypersensitivity
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Requires dosage adjustment in renal failure; caution in renal failure and coadministration of nephrotoxic drugs; associated with onset of hemolytic uremic syndrome; allogenic bone marrow transplant recipients and renal transplant recipients
After ingestion, the drug is rapidly biotransformed into the active compound penciclovir and phosphorylated by viral thymidine kinase. By competition with deoxyguanosine triphosphate, penciclovir triphosphate inhibits viral polymerase.
Adjust dose in patients with renal insufficiency or hepatic disease.
500 mg PO tid for 7 d
Not established
Coadministration of probenecid and cimetidine may increase toxicity of penciclovir; coadministration increases bioavailability of digoxin
Documented hypersensitivity
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Adjust dose in renal insufficiency or hepatic disease; not studied in immunocompromised patients or disseminated disease
Decrease pain associated with postherpetic neuralgia.
Derived from plants of the Solanaceae family. May render skin and joints insensitive to pain by depleting substance P in peripheral sensory neurons.
Apply to affected area tid/qid
<2 years: Not recommended
>2 years: Administer as in adults
None reported
Documented hypersensitivity; broken or irritated skin
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
For external use only; avoid contact with eyes, mucous membranes, wounds, or damaged skin; do not use tight bandage; discontinue use if condition worsens or symptoms persist for 14-28 d
Have anti-inflammatory properties and cause profound and varied metabolic effects. In addition, these agents modify the body's immune response to diverse stimuli. May help reduce pain, but reports are inconclusive.
Decreases inflammation by suppressing neutrophils and reversing increased capillary permeability. Also suppresses immune system.
10-50 mg PO qd
Not established
Coadministration with estrogens may decrease prednisone clearance; when used with digoxin, digitalis toxicity secondary to hypokalemia may increase; phenobarbital, phenytoin, and rifampin may increase metabolism of glucocorticoids (consider increasing maintenance dose); monitor for hypokalemia with coadministration of diuretics
Documented hypersensitivity; increased susceptibility to infection; peptic ulcer disease; hepatic dysfunction
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Abrupt discontinuation of glucocorticoids may cause adrenal crisis; hyperglycemia, edema, osteonecrosis, myopathy, peptic ulcer disease, hypokalemia, osteoporosis, euphoria, psychosis, myasthenia gravis, growth suppression, and infections may occur with glucocorticoid use
Have been shown to have a role in the treatment of postherpetic neuralgia.
Blocks reuptake of norepinephrine and serotonin. Decreases pain by inhibiting spinal neurons involved in pain perception.
10-150 mg PO hs; initially administer as smaller divided increments and gradually titrate up to an effective level with a maximum dosage of 150 mg PO qhs
Not currently recommended for children <12 y
Phenobarbital may decrease effects; coadministration with CYP2D6 enzyme system inhibitors (eg, cimetidine, quinidine) may increase amitriptyline levels; amitriptyline inhibits hypotensive effects of guanethidine; may interact with thyroid medications, alcohol, CNS depressants, barbiturates, and disulfiram
Documented hypersensitivity; administration of MAOIs in past 14 d; history of seizures; cardiac arrhythmias; glaucoma; urinary retention
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Caution in cardiac conduction disturbances, history of hyperthyroidism, and renal or hepatic impairment; avoid using in elderly patients
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.
Lyophilized preparation of Oka/Merck strain of live, attenuated varicella-zoster virus (VZV). Shown to boost immunity against herpes zoster virus (shingles) in older patients. Reduces occurrence of shingles in individuals >60 y by about 50%. For individuals aged 60-69 y, it reduces occurrence by 64%. Also slightly reduces pain compared with no vaccination in those who develop shingles. Indicated for prevention of herpes zoster.
<60 years: Not established
>60 years: Following reconstitution with entire vial of diluent supplied, use separate sterile needle and syringe to withdraw entire contents of reconstituted vial and administer SC; administer in upper arm
Not indicated
None reported
Documented hypersensitivity to vaccine or components (eg, gelatin, neomycin); history of primary or acquired immunodeficiency states (eg, leukemia, lymphomas, malignant neoplasms affecting bone marrow or lymphatic system, AIDS); immunosuppressive therapy including high-dose corticosteroids; active, untreated tuberculosis
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Common adverse effects include erythema, pain, tenderness, itching, and inflammation at injection site; may also cause headache; may cause extensive vaccine-associated rash or disseminated disease in individuals on immunosuppressive therapy (see Contraindications); defer vaccination if fever or acute illness present; do not inject intravascularly; administer within 30 min of reconstitution; not a substitute for varicella virus vaccine (Varivax) for children
The Advisory Committee on Immunization Practices (ACIP) recently issued updated adult vaccination scheduling guidelines for October 2007 through September 2008. These guidelines include changes for varicella and zoster vaccines.8
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herpes zoster, shingles, HZ, varicella-zoster virus, VZV, preherpetic neuralgia, postherpetic neuralgia, PHN, varicella, chickenpox, herpes zoster ophthalmicus, HZO, Ramsay-Hunt syndrome, herpes zoster oticus, geniculate neuralgia, herpes zoster auricularis
James E Moon, MD, Clinical Investigator, Department of Clinical Trials, Walter Reed Army Institute of Research and Assistant Professor, Department of Medicine, Uniformed Service University of Health Sciences
Disclosure: Nothing to disclose.
Duane R Hospenthal, MD, PhD, Chief, Infectious Disease Service, San Antonio Military Medical Center, Brooke Army Medical Center; Professor of Medicine, Uniformed Services University of the Health Sciences
Duane R Hospenthal, MD, PhD is a member of the following medical societies: Alpha Omega Alpha, American College of Physicians, American Society for Microbiology, American Society of Tropical Medicine and Hygiene, Armed Forces Infectious Diseases Society, Association of Military Surgeons of the US, Infectious Diseases Society of America, International Society for Infectious Diseases, International Society of Travel Medicine, and Medical Mycology Society of the Americas
Disclosure: Nothing to disclose.
Mark Raymond Wallace, MD, Infectious Disease Fellowship Director, Orlando Regional Healthcare; Clinical Professor of Medicine, Florida State University
Mark Raymond Wallace, MD is a member of the following medical societies: American College of Physicians, American Medical Association, American Society of Tropical Medicine and Hygiene, and Infectious Diseases Society of America
Disclosure: Nothing to disclose.
Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment
Gordon L Woods, MD, Consulting Staff, Department of Internal Medicine, University Medical Center
Gordon L Woods, MD is a member of the following medical societies: Society of General Internal Medicine
Disclosure: Nothing to disclose.
Eleftherios Mylonakis, MD, Clinical and Research Fellow, Department of Internal Medicine, Division of Infectious Diseases, Massachusetts General Hospital
Eleftherios Mylonakis, MD is a member of the following medical societies: American Association for the Advancement of Science, American College of Physicians, American Society for Microbiology, and Infectious Diseases Society of America
Disclosure: Nothing to disclose.
Burke A Cunha, MD, Professor of Medicine, State University of New York School of Medicine at Stony Brook; Chief, Infectious Disease Division, Winthrop-University Hospital
Burke A Cunha, MD is a member of the following medical societies: American College of Chest Physicians, American College of Physicians, and Infectious Diseases Society of America
Disclosure: Nothing to disclose.
The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting true views of the Department of the Army or the Department of Defense.
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