Chickenpox Disease

BASICS

DESCRIPTION

A common, highly contagious, childhood exanthem characterized by the development of typical crops of vesicles on the skin and mucous membranes.

The virus is spread by respiratory droplets or direct contact with vesicles or indirectly through freshly soiled articles
Outbreaks tend to occur from January to May
The usual incubation period is 14-16 days (range 11-21). Patients are infectious from approximately 48 hours before appearance of the rash until the final lesions have crusted. Most people acquire chickenpox during childhood and develop long immunity.
System(s) affected: Skin/Exocrine, Nervous
Genetics: No known genetic pattern
Incidence/Prevalence in USA: Common
Predominant age: Peak incidence 5-9 years, but may occur at any age
Predominant sex: Male = Female

SIGNS AND SYMPTOMS

Prodromal symptoms - fever, malaise, anorexia, mild headache
Characteristic rash - crops of "teardrop" vesicles on erythematous bases
Lesions erupt in successive crops
Progress from macule to papule to vesicle, then begin to crust
Rash present in various stages of development
Pruritic
Usually begins on trunk, then spreads to face and scalp
Minimal involvement of the extremities
Lesions may be present on mucous membranes, oral and vaginal

CAUSES

Human (alpha) herpesvirus 3 (varicella-zoster virus, V-Z virus), a member of the Herpesvirus group; a double-stranded DNA virus. (Reservoir: humans.)

RISK FACTORS

No prior history of varicella
Immunosuppressed (especially children with leukemia/lymphoma in remission or on high-dose corticosteroids)

DIAGNOSIS

LABORATORY

Leukocyte count may be normal, low, or mildly increased
Marked leukocytosis is suggestive of secondary infection
Multinucleated giant cells on Tzanck smear from scrapings of vesicles
Isolated virus from human tissue culture

Drugs that may alter lab results: N/A
Disorders that may alter lab results:

Herpes zoster
Herpes simplex

PATHOLOGICAL FINDINGS

Skin lesions histologically identical to herpes simplex virus
In fatal cases intranuclear inclusions can be found in the endothelium of blood vessels and most organs

SPECIAL TESTS

For complicated cases and epidemiologic studies:

Visualization of the virus by EM
Serologic testing by FAMA or ELISA
Detection of viral DNA by PCR

IMAGING

N/A

DIAGNOSTIC PROCEDURES

N/A

TREATMENT

APPROPRIATE HEALTH CARE

Outpatient except for complicating emergencies

GENERAL MEASURES

Supportive/symptomatic treatment
Good hygiene to avoid secondary infection

SURGICAL MEASURES

N/A

ACTIVITY

As tolerated. Children may return to school when lesions have scabbed over, temperature is normal and sense of well-being has returned.

DIET

No special diet

PATIENT EDUCATION

Griffith: Instructions for Patients; Philadelphia, 1994, W.B. Saunders Co.

FOLLOW UP

PREVENTION/AVOIDANCE

Exposed, susceptible individuals considered infectious for 21 days
Isolation of hospitalized patients
Passive immunization with ZIG, VZIG, or the intravenous formulation of ZIP. Both ZIG and VZIG should be given within 96 hours (preferably within 72 hours) of exposure to ensure efficacy. ZIP can be given somewhat later. Recommended for persons exposed to chickenpox or shingles within 96 hours who are immunocompromised, ³15 years old without prior history of chickenpox, newborns of mothers with onset of chickenpox < 5 days before delivery or < 2 days after delivery. Exposure criteria: continued household contact, prolonged face-to-face contact (same room), or indoor playmate > 1 hour.
Varicella-Virus vaccine (Varivax) - a live attenuated vaccine approved by the FDA and recommended by ACIP for immunization of healthy individuals, 12 months and above, who have not had chickenpox. Duration of immunity is unknown
- 12m-12y: single dose 0.5 mL SC. Cumulative efficacy 70-90%
- 13y and above: two 0.5 mL SC doses 4-8 weeks apart. Efficacy 70%.
- Has been shown to prevent or significantly reduce the severity of varicella if given within 72 hours and possibly up to 5 days, postexposure in several studies.
- Maybe considered for a subset of HIV positive children in CDC Class I with CD4 > 25%
Vaccine recipients should avoid contact with immunocompromised people, and pregnant women who have never had chickenpox and their newborns, for up to 6 weeks after vaccination

POSSIBLE COMPLICATIONS

Secondary bacterial infection - cellulitis, abscess, erysipelas, sepsis, septic arthritis/osteomyelitis, staphylococcal pyomyositis
Pneumonia (20-30% of adults with chickenpox have lung involvement)
Encephalitis (the most common CNS complication)
Reye's syndrome
Purpura
Lymphadenitis
Nephritis

EXPECTED COURSE AND PROGNOSIS

In the healthy child, chickenpox is rarely a serious disease and recovery is complete
Confers long immunity
Second attack rare, but subclinical infection common
Infection latent and may recur years later as herpes zoster in adults (and sometimes in children)
Fatalities rarely occur from complications

MISCELLANEOUS

ASSOCIATED CONDITIONS

N/A

AGE-RELATED FACTORS

Pediatric:

Neonates born to mothers who develop chickenpox 5 days before or 2 days after delivery are at risk for serious disease. Must give VZIG.
Varicella bullosa seen mainly in children under two. Lesions appear as bullae instead of vesicles. Clinical course unchanged.
Case-fatality (in USA) 2/100,000
Most common cause of death: septic complications and encephalitis

Geriatric:

Infection more severe than in children
Latent varicella infection may reactivate and cause the exanthem shingles or zoster
Case-fatality 30/100,000
Most common cause of death: primary viral pneumonia

Others: N/A

PREGNANCY

Risk of transplacental infection following maternal infection is 25%. Congenital malformations are seen in 5% when the fetus is infected during the 1st or 2nd trimester. There is an increased morbidity for women infected during pregnancy (e.g., pneumonia)

OTHER NOTES

N/A

ABBREVIATIONS

ACIP = Advisory Committee on Immunization Practices
FAMA = fluorescent antibody to membrane antigen
ZIG = zoster immune globulin
ZIP = zoster immune plasma
DNA = deoxyribonucleic acid
EM = electron microscopy
PCR = polymerase chain reaction
VZIG = varicella-zoster immune globulin

Clinical Investigations

ROLE OF HOMOEOPATHY

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