Introduction
Background
The varicella-zoster virus (VZV) is the etiologic agent of the clinical syndrome of chickenpox (varicella). Zoster, a different clinical entity, is caused by reactivation of VZV after primary infection. VZV is a double-stranded DNA virus included in the Alphaherpesvirinae subfamily. Chickenpox is largely a childhood disease, with more than 90% of cases occurring in children younger than 10 years. The disease is benign in the healthy child, whereas increased morbidity is seen in adults and in patients who are immunocompromised.
Pathophysiology
Chickenpox is usually acquired by the inhalation of airborne respiratory droplets from an infected host. The highly contagious nature of VZV explains the epidemics of chickenpox that spread through schools as one child who is infected quickly spreads the virus to many classmates. High viral titers are found in the characteristic vesicles of chickenpox; thus, viral transmission may also occur through direct contact with these vesicles, although the risk is lower.
After initial inhalation of contaminated respiratory droplets, the virus infects the conjunctivae or the mucosae of the upper respiratory tract. Viral proliferation occurs in regional lymph nodes of the upper respiratory tract 2-4 days after initial infection and is followed by primary viremia on postinfection days 4-6. A second round of viral replication occurs in the body's internal organs, most notably the liver and the spleen, followed by a secondary viremia 14-16 days postinfection. This secondary viremia is characterized by diffuse viral invasion of capillary endothelial cells and the epidermis. VZV infection of cells of the malpighian layer produces both intercellular edema and intracellular edema, resulting in the characteristic vesicle.
Exposure to VZV in a healthy child initiates the production of host immunoglobulin G (IgG), immunoglobulin M (IgM), and immunoglobulin A (IgA) antibodies; IgG antibodies persist for life and confer immunity. Cell-mediated immune responses are also important in limiting the scope and the duration of primary varicella infection. After primary infection, VZV is hypothesized to spread from mucosal and epidermal lesions to local sensory nerves. VZV then remains latent in the dorsal ganglion cells of the sensory nerves. Reactivation of VZV results in the clinically distinct syndrome of herpes zoster (shingles).
Frequency
United States
Chickenpox is a common disease, with most cases occurring in the pediatric population. Since the introduction of widespread pediatric immunization in the United States in 1995, the incidence of varicella has declined significantly, approaching up to 90% in one study. Mortality from varicella has also similarly decreased since the initiation of the US vaccination program, with the mortality rate decreasing by approximately 66% in one study.1
International
Countries with tropical and semitropical climates have a higher incidence of adult chickenpox compared with countries with a temperate climate (eg, United States, Europe).
Mortality/Morbidity
Chickenpox affecting a healthy child is usually a self-limited disease. Secondary bacterial infection of skin lesions, manifesting as impetigo, cellulitis, or erysipelas, is the most common complication in this population. Staphylococci and streptococci are the most commonly implicated bacterial pathogens. Bacterial superinfection may predispose to scarring. Localized bacterial superinfection may rarely result in septicemia, culminating in a secondary bacterial pneumonia, otitis media, or necrotizing fasciitis (see Complications).Congenital infection with the VZV is also a concern. Maternal chickenpox during pregnancy may produce latency of the VZV in the dorsal root ganglia of the fetus. These children may remain asymptomatic, or they may develop herpes zoster at a young age without previous history of primary chickenpox infection. Primary maternal chickenpox infection during the first 20 weeks of gestation may also rarely produce the congenital varicella syndrome, which is characterized by limb hypoplasia, muscular atrophy, skin scarring, cortical atrophy, microcephaly, cataract formation, and rudimentary digits (see Special Concerns).2,3
Race
Varicella has no racial predilection.
Sex
Varicella has no sexual predilection.
Age
Chickenpox is predominantly a pediatric disease.
Clinical
History
Chickenpox is usually diagnosed clinically on the basis of the characteristic rash and successive crops of lesions. Lesions may be found in all stages of development and healing in affected sites. A history of exposure to an infected contact within the incubation period of 10-21 days is also an important clue in the diagnosis.
- Childhood chickenpox is usually not heralded by a prodrome, but rather it begins with the onset of an exanthem.
- Chickenpox in adults and adolescents may be preceded by a prodrome of nausea, myalgia, anorexia, and headache.
- The typical patient is infectious for 1-2 days prior to the development of rash and for 4-5 days afterwards, which is usually the time at which the last crop of vesicles has crusted over.
- The triad of rash, malaise, and low-grade fever signals the onset of chickenpox.
- Small, erythematous macules appear on the scalp, the face, the trunk, and the proximal limbs, with rapid sequential progression over 12-14 hours to papules, clear vesicles, and pustules, with subsequent central umbilication and crust formation.
- New crops of lesions form, which subsequently progress to vesicles with crusting.
- Vesicles may appear on the palms and the soles and on the mucous membranes, with painful, shallow, oropharyngeal or urogenital ulcers.
- Intense pruritus commonly accompanies the vesicular stage of the rash.
Physical
- The characteristic chickenpox vesicle, surrounded by an erythematous halo, is described as a dewdrop on a rose petal (see Media Files 1-2).
Dewdrop on rose petal characteristic vesicle of chickenpox. Reprinted with permission from Cutis 65: 355, 2000.
Vesicular eruption on the trunk demonstrating papules, vesicles, and crusts. Reprinted with permission from Cutis 65: 355, 2000.
- Chickenpox is clinically characterized by the presence of active and healing lesions, in all stages of development, within affected locations.
- Lesions characteristically heal without scarring, though excoriation or secondary bacterial superinfection predispose to scar formation.
- Adults with chickenpox have a more complicated course than that occurring in children. Adults may experience a more widespread rash; prolonged fever; and an increased likelihood of complications, the most common being varicella pneumonia.
- Clinical variants of chickenpox infection also occur.
- Hemorrhagic lesions (see Complications) are rare and are most commonly associated with patients who are immunocompromised or immunosuppressed.
- Bullous chickenpox is a rare variant in which bullae appear instead of the characteristic vesicles.4 The possibility of bullous impetigo from Staphylococcus aureus must be addressed, especially in a child with persistent fever or relapse after he or she appeared to be improving. Bullous chickenpox may affect both children and adults and must be differentiated from other bullous disorders (eg, bullous pemphigoid, pemphigus).
- The course of the disease is believed to be unchanged, although a delay in diagnosis and treatment of elderly patients and patients who are immunocompromised may lead to serious morbidity.
- Chickenpox and other viral exanthems may appear concentrated in areas where intense sun exposure occurred during the incubation period. Patients with atopic dermatitis may show an atypical distribution of varicella, in which the characteristic eruption is primarily found on lichenified areas.5
Causes
Chickenpox is usually acquired by the inhalation of airborne respiratory droplets from a VZV-infected host. High viral titers are found in the characteristic vesicles of chickenpox; thus, viral transmission may also occur through direct contact with these vesicles.
More on Chickenpox |
 Overview: Chickenpox |
| Differential Diagnoses & Workup: Chickenpox |
| Treatment & Medication: Chickenpox |
| Follow-up: Chickenpox |
| Multimedia: Chickenpox |
| References |
| Next Page » |
References
Nguyen HQ, Jumaan AO, Seward JF. Decline in mortality due to varicella after implementation of varicella vaccination in the United States. N Engl J Med. Feb 3 2005;352(5):450-8. [Medline].
Forrest J, Mego S, Burgess M. Congenital and neonatal varicella in Australia. J Paediatr Child Health. Apr 2000;36(2):108-13. [Medline].
Auriti C, Piersigilli F, De Gasperis MR, Seganti G. Congenital Varicella Syndrome: Still a Problem?. Fetal Diagn Ther. May 27 2009;25(2):224-229. [Medline].
Schwartz RA, Jordan MC, Rubenstein DJ. Bullous chickenpox. J Am Acad Dermatol. Aug 1983;9(2):209-12. [Medline].
Hirota T, Hirota Y, Ichimiya M, et al. Atypical varicella seen in a woman with atopic dermatitis. Acta Dermatol Kyoto. 1998;93(1):65-8.
Nahass GT, Goldstein BA, Zhu WY, Serfling U, Penneys NS, Leonardi CL. Comparison of Tzanck smear, viral culture, and DNA diagnostic methods in detection of herpes simplex and varicella-zoster infection. JAMA. Nov 11 1992;268(18):2541-4. [Medline].
Harbecke R, Oxman MN, Arnold BA, et al. A real-time PCR assay to identify and discriminate among wild-type and vaccine strains of varicella-zoster virus and herpes simplex virus in clinical specimens, and comparison with the clinical diagnoses. J Med Virol. Jul 2009;81(7):1310-22. [Medline].
Dunkle LM, Arvin AM, Whitley RJ, et al. A controlled trial of acyclovir for chickenpox in normal children. N Engl J Med. Nov 28 1991;325(22):1539-44. [Medline].
Vinzio S, Lioure B, Goichot B. Varicella in immunocompromised patients. Lancet. Dec 23 2006;368(9554):2208. [Medline].
Safrin S, Berger TG, Gilson I, et al. Foscarnet therapy in five patients with AIDS and acyclovir-resistant varicella-zoster virus infection. Ann Intern Med. Jul 1 1991;115(1):19-21. [Medline].
Chartrand SA. Varicella vaccine. Pediatr Clin North Am. Apr 2000;47(2):373-94. [Medline].
Durrheim DN. Varicella vaccine: local convenience or global equity?. Lancet. Dec 23 2006;368(9554):2208-9. [Medline].
Kamiya H, Ito M. Update on varicella vaccine. Curr Opin Pediatr. Feb 1999;11(1):3-8. [Medline].
Vázquez M, Shapiro ED. Varicella vaccine and infection with varicella-zoster virus. N Engl J Med. Feb 3 2005;352(5):439-40. [Medline].
Wutzler P, Knuf M, Liese J. Varicella: efficacy of two-dose vaccination in childhood. Dtsch Arztebl Int. Aug 2008;105(33):567-72. [Medline].
Asano Y, Nagai T, Miyata T, et al. Long-term protective immunity of recipients of the OKA strain of live varicella vaccine. Pediatrics. Apr 1985;75(4):667-71. [Medline].
[Guideline] Centers for Disease Control and Prevention. A new product (VariZIG) for postexposure prophylaxis of varicella available under an investigational new drug application expanded access protocol. MMWR Morb Mortal Wkly Rep. Mar 3 2006;55(8):209-10. [Medline].
[Guideline] American Academy of Pediatrics Committee on Infectious Diseases. Prevention of varicella: recommendations for use of varicella vaccines in children, including a recommendation for a routine 2-dose varicella immunization schedule. Pediatrics. Jul 2007;120(1):221-31. [Medline].
[Guideline] Centers for Disease Control and Prevention, Advisory Committee on Immunization Practices. Update: recommendations from the Advisory Committee on Immunization Practices (ACIP) regarding administration of combination MMRV vaccine. MMWR Morb Mortal Wkly Rep. Mar 14 2008;57(10):258-60. [Medline].
[Guideline] American Academy of Pediatrics Committee on Infectious Diseases. Recommended childhood and adolescent immunization schedules--United States, 2009. Pediatrics. Jan 2009;123(1):189-90. [Medline].
[Guideline] Centers for Disease Control and Prevention, Advisory Committee on Immunization Practices. Recommended adult immunization schedule: United States, 2009*. Ann Intern Med. Jan 6 2009;150(1):40-4. [Medline].
Aebi C, Ahmed A, Ramilo O. Bacterial complications of primary varicella in children. Clin Infect Dis. Oct 1996;23(4):698-705. [Medline].
Higuchi S, Toichi E, Kore-eda S, et al. An adult case of Fournier's gangrene preceded by varicella. Acta Dermatol Kyoto. 1997;92(4):375-80.
Choo PW, Donahue JG, Manson JE, Platt R. The epidemiology of varicella and its complications. J Infect Dis. Sep 1995;172(3):706-12. [Medline].
LaRussa P, Steinberg S, Meurice F, Gershon A. Transmission of vaccine strain varicella-zoster virus from a healthy adult with vaccine-associated rash to susceptible household contacts. J Infect Dis. Oct 1997;176(4):1072-5. [Medline].
Lunghi F, Finzi M. Varicella bullosa in HIV+ adults. Chronica Dermatologica (Roma). 1997;7:557-60.
McCrary ML, Severson J, Tyring SK. Varicella zoster virus. J Am Acad Dermatol. Jul 1999;41(1):1-14; quiz 15-6. [Medline].
Miller HC, Stephan M. Hemorrhagic varicella: a case report and review of the complications of varicella in children. Am J Emerg Med. Nov 1993;11(6):633-8. [Medline].
Papadopoulos AJ, Schwartz RA, Janniger CK. Chickenpox. Cutis. Jun 2000;65(6):355-8. [Medline].
Snoeck R, Andrei G, De Clercq E. Current pharmacological approaches to the therapy of varicella zoster virus infections: a guide to treatment. Drugs. Feb 1999;57(2):187-206. [Medline].
Tsunoda T, Ogawa S. A consideration on the distribution of eruption of herpes zoster. Acta Dermatol Kyoto. 1986;81:95-8.
Further Reading
Keywords
chickenpox, chicken pox, primary varicella, primary varicella infection, varicella-zoster virus, varicella zoster virus, VZV, herpes zoster, shingles
