eMedicine Specialties > Emergency Medicine > Pediatric

Pediatrics, Chicken Pox or Varicella

Author: Richard Lichenstein, MD, Associate Professor, Pediatric Emergency Department, University of Maryland School of Medicine
Contributor Information and Disclosures

Updated: Sep 17, 2008

Introduction

Background

Varicella, or chickenpox, is usually a benign, self-limited, primary infection that affects approximately 4 million children per year in the United States. Varicella also accounts for significant morbidity (4000 hospitalizations per year) and mortality (50-100 deaths per year) in otherwise healthy children; moreover, the annual cost of chickenpox has been estimated at $400 million in medical costs and lost wages in the past. Universal immunization against varicella was first recommended in 1995 and has lead to a reduction in mortality, varicella-related hospitalizations, and hospital-related charges for children and adults in the United States.

Pathophysiology

Primary varicella is caused by the varicella-zoster (V-Z) virus, a herpes virus. Inhalation of virus-infected respiratory secretions or direct contact with skin lesions can produce disease.

Infection usually occurs through the conjunctival or upper respiratory mucosa. Viral replication takes place in regional lymph nodes over the next 2-4 days and is followed by a primary viremia occurring 4-6 days after initial inoculation. The virus then replicates in the liver, spleen, and possibly other organs. This secondary viremia, featuring viral particles being spread to the skin 14-16 days after initial exposure, causes the typical vesicular rash. Encephalitis, hepatitis, or pneumonia also may occur at this time.

The usual incubation period is 10-21 days. The patient is contagious from 1-2 days before the appearance of rash until the lesions crust over, usually 5-6 days after the rash first appears.

Although most varicella infection confers life-long immunity, varicella clinical reinfections among healthy children have been described.

Frequency

United States

In the pre-universal vaccination era, national seroprevalence data for 1988-1994 indicated that 95.5% of adults aged 20-29 years, 98.9% of adults aged 30-39 years, and more than 99.6% of adults aged >40 years were immune to varicella. By 2000, vaccination coverage among children 19-35 months in 3 communities in Texas, California, and Pennsylvania had reached 74-84%, and reported total varicella cases had declined 71-84%. The majority of decline occurred among children aged 12 months to 4 years; however, incidence declined in all age groups, including infants and adults.

International

Varicella is almost universal; an estimated 60 million cases occur worldwide each year. A survey of 1473 cases in Japan demonstrated that 81.4% involved children younger than 6 years. In Japan, the annual prevalence peaked between March and May, with subsequent lower prevalence between August and October. The epidemiology of varicella differs between countries with temperate and tropical climates. In most countries with temperate climates, more than 90% of persons are infected by adolescence but in countries with tropical climates, a higher proportion of infections are acquired at older ages, which results in higher susceptibility among adults.

Mortality/Morbidity

In immunocompromised children, such as those with leukemia, mortality rates from varicella have ranged from 7-28%. The case-fatality rate in the general population is 6.7 case per 100,000.

• Morbidity is due to overwhelming viremia, encephalitis, bacterial superinfection, pneumonia, and Reye syndrome (which is associated with aspirin use). Common complications include secondary staphylococcal or streptococcal infections of the skin and upper respiratory tract, including otitis media. Central nervous system complications include aseptic meningitis and Guillain-Barré syndrome. Other complications include thrombocytopenia, arthritis, hepatitis, and glomerulonephritis.
• In pregnant women, varicella during the first 20 weeks of gestation can lead to multiple congenital anomalies including limb atrophy, neurologic and ocular abnormalities, as well as growth retardation.
• Infants born to women who have varicella 5 days or fewer before delivery or 2 days postpartum may develop disseminated varicella neonatorum. Hemorrhagic lesions of the liver and lungs characterize this potentially fatal disease.

Sex

Varicella has no sex predilection.

Age

Varicella is most commonly observed in children aged 3-6 years.

• Though most cases of varicella in the United States occur in children younger than 10 years, 5% of cases are in persons older than 15 years.
• In tropical climates, varicella is more common in older children.
• The majority of cases in Japan were in children younger than 6 years. Approximately 9.6% of cases involved children younger than 1 year, and almost one third of these were infants younger than 5 months.

Clinical

History

• The history should describe if a recent outbreak of chickenpox in the community has occurred and if any exposure to varicella at school, daycare, or among family members has occurred. It should also be noted whether the child has previously received varicella vaccine or if the child is immunocompromised.
• Ask parents whether their child had chickenpox previously.
• Prodromal symptoms
  • Fever
  • Malaise
  • Anorexia
  • Headache
• Lesions erupt in successive crops, usually beginning on the trunk and then spreading to the face and scalp.
• Lesions frequently involve the pharynx and tonsils.
• The rash is most often described as being very itchy.
• A careful history should investigate the possibility of immunodeficiency (including recent systemic steroid use) to help guide management.

Physical

The diagnosis is made with the characteristic rash. Ill appearance should raise concern for pulmonary or CNS complications or serious bacterial superinfection.

• The classic lesion has been described as an "oval teardrop on an erythematous base" or a "dew drop on a rose petal."
• Skin lesions initially appear on the face and trunk, beginning as red macules and progressing over 12-14 days to become papular, vesicular, pustular, and finally crusted.
• The lesions predominate in central skin areas and proximal upper extremities with relative sparing of distal and lower extremities but spread to other skin areas.
• A characteristic feature of the rash is that the lesions can be in all stages of development simultaneously.
• Vesicles may occur on mucous membranes and break down to form shallow aphthous ulcers.
• A patient's temperature can be as high as 39.5°C and can last 3-6 days after the development of the rash.
• Vesicles can be hemorrhagic.
• Dermatomal distribution of lesions is characteristic of reactivation rather than primary infection.
• Identify right upper quadrant pain with or without associated jaundice.
• Although tachypnea may be seen with fever alone, respiratory distress might represent pneumonitis.
• A careful neurologic examination can identify associated meningo-encephalitis.
• Cerebellitis, as noted by ataxia, is associated with varicella infection.
• Look for signs of bacterial superinfection.
  • Superficial infection with impetigo
  • Cellulitis
  • Necrotizing fasciitis
  • Arthritis, osteomyelitis

Causes

• Human (alpha) herpesvirus 3 (V-Z virus), a member of the herpesvirus group, is responsible for the development of varicella.
• Direct person-to-person contact with lesions and/or airborne droplets spreads the V-Z virus. Neonatal varicella is caused by maternal viremia, leading to spread of the virus across the placenta.
• Risk factors
  • No prior history of varicella
  • Unvaccinated status
  • Immunosuppression

• Search for CME/CE on This Topic »

• Syndrome of Inappropriate Antidiuretic Hormone Secretion (Pediatrics: General Medicine)
• Ellis-van Creveld Syndrome (Pediatrics: Genetics and Metabolic Disease)
• Pediatrics, Apnea (Emergency Medicine)
• Ethical and Legal Considerations in Pediatric Surgery (Pediatrics: Surgery)

• Chickenpox Causes
• Bacterial and Viral Infections Center
• Chickenpox Overview
• Chickenpox Symptoms
• Chickenpox Treatment
• Skin Rashes in Children Introduction

• American Academy of Pediatrics Updates Guidelines for Use of Rotavirus Vaccine
• PAS 2009: AAP Guidelines for Acute Otitis Media May Encourage Overtreatment
• Guidelines Issued on Management of Abusive Head Trauma in Infants and Children

• Essential Resources for Pediatrics
• Pacemaker and Defibrillator Therapy in Pediatrics and Congenital Heart Disease
• Improving Pediatrics Medication Safety Part I: Research on Medication Errors and Recommendations from the Joint Commission

• Pediatrics/Neonatal Care Nursing Resource Center
• Growth and Development