Varicella

  • What is varicella?

    Varicella (commonly known as chickenpox) is caused by varicella-zoster virus. It usually occurs in childhood and is characterized by a generalized pruritic vesicular rash and fever.1

  • What are the symptoms of varicella zoster and its manifestations?

    Symptoms that develop prior to the onset of rash include malaise, pruritus, anorexia, and listlessness.1,2

    Skin manifestations in varying stages of evolution consist of maculopapules, vesicles, pustules, and scabs.1,2

    At first, the lesions contain clear fluid, pustulating and scabbing over a short period of time. Rash initially appears on the trunk and face, quickly spreading to other areas of the body. Successive crops of lesions generally continue over a period of 2 to 4 days. Crusts completely fall off within 1 to 2 weeks after infection begins and can leave a slightly depressed area in the skin.1,2

  • How is varicella transmitted?

    The most common mode of transmission of varicella-zoster virus is believed to be person to person from infected respiratory tract secretions2 containing the varicella-zoster virus that come into contact with the mucosa of the upper respiratory tract or the conjunctiva of the eye.3 The virus is believed to replicate at the site entry in the nasopharynx and in regional lymph nodes.1 Varicella is usually contagious from 1 to 2 days before onset of rash until lesions have formed crusts.1

  • What are the clinical features of varicella over time?

    Pathogenesis of varicella4

    • Day
      0
      1. INFECTION
      DAY 0

      Varicella-zoster virus infects the mucosa of the upper respiratory tract or the conjunctiva of the eye. The virus is thought to replicate in the nasopharynx and regional lymph nodes of the head and neck.1,5

      Clinical Features of Varicella Over TimeClinical Features of Varicella Over Time

    • Day
      4–6
      2. PRIMARY VIREMIA
      DAY 4–6

      Infected T-cells enter the blood stream causing a primary viremia characterized by malaise, fever, and aching back/extremities. Infected T-cells then move to the viscera and sensory ganglia. On the sensory ganglia, a second round of viral replication takes place.1,5,6

      Clinical Features of Varicella Over TimeClinical Features of Varicella Over Time

    • Day
      14
      3. SECONDARY VIREMIA
      ~DAY 14 (can range from 10–21 days)

      Varicella-zoster virus spreads to the skin by way of a secondary viremia, leading to a generalized, pruritic vesicular rash.5

      Clinical Features of Varicella Over TimeClinical Features of Varicella Over Time

    Day 0 Day 14
    14-day incubation (range: 10–21 days)
  • How is varicella diagnosed?

    A varicella diagnosis can be typically based on:

    Age of the patient1
    Exposure to someone with varicella or herpes zoster within the last 2–3 weeks7
    Season during which the rash occurs (In the United States, the incidence of varicella is highest between March and May.)1
    Rash that:
    • Is itchy (pruritic)1
    • Is accompanied by pain and low-grade fever1
    • Is characterized by lesions that are scattered vs clustered and are located initially on the face and head and then spread to the trunk, with possible sparing of the extremities.7
    • Progresses quickly from macules to papules, vesicles, pustules, and finally crusts1,7

  • What are the complications of varicella?
    Possible Varicella Complications
    CutaneousNeurologicPneumonic
    • Bacterial skin infections that can lead to more serious infections such as bacteremia, toxic shock syndrome, and necrotizing fasciitis7,8
    • Acute cerebellar ataxia and encephalitis7
    • Other rare neurologic complications include:
      • Reye's syndrome7
      • Aseptic meningitis1
      • Transverse myelitis1
      • Guillain-Barré syndrome1
      • Possible increased risk of stroke8,9
    • Varicella pneumonia occurs more frequently in healthy adults and is characterized by:
      • Cough
      • Dyspnea
      • High fever7
    • These symptoms may also be accompanied by pleuritic chest pain or hemoptysis7

    Populations at increased risk of severe varicella illness and/or complications1,10:

    • Healthy adults
    • Immunocompromised individuals
    • Children with lymphoma, leukemia, or HIV
    • Pregnant women
    • Developing fetuses
    • Susceptible infants and neonates
  • What happens if a pregnant woman contracts varicella?

    There is a risk of congenital varicella syndrome if the mother contracts varicella in the first 20 weeks of pregnancy. Infant abnormalities include low birth weight, hypoplasia of an extremity, localized muscular atrophy, chorioretinitis, encephalitis, brain atrophy, and death.1,11

    If the mother contracts varicella during the perinatal phase, varicella can infect the infant by transplacental viremia (intrauterine exposure), ascending infection during birth, or direct contact with infectious lesions after birth.11

    Varicella during the first 12 days of life is attributed to intrauterine exposure, whereas infection after 12 days of birth is attributed to postnatal infection, given a rough 12-day incubation period in the neonate.11

    Maternal disease between 20 to 6 days before delivery, or neonatal onset from 5 to 10 days post delivery have resulted in somewhat mild outcomes as infants have had a chance to acquire maternal antibodies to avoid long-term complications. However, maternal disease between 5 days before to 2 days after delivery, or neonatal onset from 5 to 10 days after delivery have resulted in fatal outcomes in 20%-23% of the cases reported.11

    Premature neonates aged <28 weeks gestation at birth have a high risk of severe varicella during the first 6 weeks after birth as there appears to be no protective maternal antibodies because of reduced gestational period.11

  • How does geography affect the disease epidemiology of varicella?
    In Regions With Warmer Summers and Cooler Winters, 90% of the Population Is Infected With Varicella Prior to AdolescenceTemperate Climates In regions with warmer summers and cooler winters, 90% of the population is infected with varicella prior to adolescence.12
    In Tropical Climates, It's Adolescents and Adults Who More Commonly Get VaricellaTropical Climates In tropical climates, it's adolescents and adults who more commonly get varicella.12
    • Peak incidence of varicella typically occurs in the cooler months of the year (ie, winter or spring).12
  • Has the prevalence of varicella changed since the introduction of the varicella vaccine?

    From 1995 to 2010 in the U.S. surveillance sites, there was a:

    • ~98% decline in the number of varicella cases at both surveillance sites since 1995.
    • >85% decline in the number of varicella-related hospitalizations in 2006-2010, compared with 1995-1998.13
Disease Information

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CDC Information

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VACC-1263237-0000 11/18
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1. Centers for Disease Control and Prevention (CDC). Varicella. In: Hamborsky J, Kroger A, Wolfe S, eds. Epidemiology and Prevention of Vaccine-Preventable Diseases. 13th ed. Washington, DC: Public Health Foundation; 2015:353–376. http://www.cdc.gov/vaccines/pubs/pinkbook/index.html. Accessed August 27, 2018.
2. Whitley RJ. Chickenpox and herpes zoster (varicella-zoster virus). In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases.
Vol 2. 8th ed. Philadelphia, PA: Elsevier Saunders; 2015:1731–1737.
3. McCary J. Herpes zoster (shingles). In: O'Connell JJ, ed. The Health Care of Homeless Persons. Boston, MA: Boston Health Care for the Homeless Program; 2004:47–51.
4. Gershon AA, Takahashi M, Seward JF. Varicella vaccine. In: Plotkin SA, Orenstein WA, Offit PA, eds. Vaccines. 5th ed. Philadelphia, PA: Saunders Elsevier; 2008:915–958.
5. Gershon AA, Silverstein SJ. Varicella-zoster virus. In: Richman DD, Whitley RJ, Hayden FG. Clinical Virology. 3rd ed. Washington, DC: ASM Press; 2009:451–472.
6. Grose C. Pathogenesis of infection with varicella vaccine. Infect Dis Clin North Am. 1996;10(3):489–505.
7. Schmader KE, Oxman MN. Varicella and herpes zoster. In: Fitzpatrick's Dermatology in General Medicine. 8th ed. New York, NY: McGraw-Hill; 2012:1–43.
8. deVeber G. Risk factors for childhood stroke: little folks have different strokes! Ann Neurol. 2003;53 (2):149-150.
9. Miravet E, Danchaivijitr N, Basu H, Saunders DE, Ganesan V. Clinical and radiological features of childhood cerebral infarction following varicella zoster virus infection. Dev Med Child Neurol. 2007;49(6)417-422.
10. Gnann JW Jr. Varicella-zoster virus: atypical presentations and unusual complications. J Infect Dis. 2002;186(suppl 1):S91–S98.
11. Sauerbrei A. Review of varicella-zoster virus infections in pregnant women and neonates. Health. 2010;2(2):143–152.
12. Heininger U, Seward JF. Varicella. Lancet. 2006;368:1365–1376.
13. Bialek SR, Perella D, Zhang J, et al. Impact of a routine two-dose varicella vaccination program on varicella epidemiology. Pediatrics. 2013;132:e1134–e1140.