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Varicella-Zoster Virus (Chickenpox)

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Last Update: October 15, 2022.

Continuing Education Activity

Chickenpox or varicella is a contagious disease caused by the varicella-zoster virus. The virus is responsible for chickenpox (usually primary infection in nonimmune hosts) and herpes zoster or shingles (following reactivation of latent infection). Chickenpox results in a skin rash that forms small, itchy blisters that scab over. This activity describes the cause, presentation, and pathophysiology of chickenpox and highlights the interprofessional team's role in treating and preventing this infection.


  • Identify the etiology of chickenpox.
  • Evaluate the presentation of chickenpox.
  • Determine the treatment and management options available for chickenpox.
  • Communicate interprofessional team strategies for improving care coordination and outcomes in patients with chickenpox.
Access free multiple choice questions on this topic.


Chickenpox or varicella is a contagious disease caused by the varicella-zoster virus (VZV). The virus is responsible for chickenpox (usually primary infection in non-immune hosts) and herpes zoster or shingles (following reactivation of latent infection). Chickenpox results in a skin rash forming small, itchy blisters that scabs over. It typically starts on the chest, back, and face and then spreads. It is accompanied by fever, fatigue, pharyngitis, and headaches, usually lasting 5 to 7 days. Complications include pneumonia, brain inflammation, and bacterial skin infections. The disease is more severe in adults than in children. Symptoms begin ten to 21 days after exposure, but the average incubation period is about 2 weeks (see Image. Chickenpox [Varicella]).

Chickenpox is an airborne disease spread worldwide by coughing, sneezing, and contact with skin lesions. It may spread 1 to 2 days before the rash appears until all lesions are crusted over. Patients with shingles may spread chickenpox to those who are not immune through blister contact. The disease is diagnosed based on the presenting symptoms and confirmed by polymerase chain reaction (PCR) testing of the blister fluid or scabs. Tests for antibodies may be performed to determine if immunity is present. Although reinfections by varicella may occur, these reinfections are usually asymptomatic and much milder than the primary infection.

The varicella vaccine was introduced in 1995 and has significantly decreased the number of cases and complications. It prevents about 70% to 90% of infections and 95% of severe disease. Routine immunization of children is recommended. Immunization within 3 days of exposure may still improve outcomes in children.[1][2][3]


Chickenpox or varicella is caused by the varicella-zoster virus (VZV), a herpes virus with worldwide distribution. It establishes latency after primary infection, a feature unique to most herpes viruses.[4]

Chickenpox is acquired by inhalation of infected aerosolized droplets. This virus is highly contagious and can spread rapidly. The initial infection is in the mucosa of the upper airways. The virus enters the circulation after 2 to 6 days, and another bout of viremia occurs in 10 to 12 days. At this time, the characteristic vesicle appears. Immunoglobulin (Ig)A, IgM, and IgG antibodies are produced, but the IgG antibodies confer lifelong immunity. After the primary infection, varicella localized to sensory nerves and may reactivate later to produce shingles.


Varicella occurs in all countries and is responsible annually for about 7000 deaths. In temperate countries, it is a common disease in children, with most cases occurring in winter and spring. In the United States, it accounts for more than 9000 hospitalizations annually. Its highest prevalence is in the 4- to 10-year-old age group. Varicella has an infection rate of 90%. Secondary cases in household contacts tend to have more severe disease than primary cases. In the tropics, varicella tends to occur in older people and may cause more serious disease. Adults get deep pockmarks and more prominent scars.[5][6][7]


Exposure causes the production of host IgG, IgM, and IgA. IgG antibodies persist for life and confer immunity. Cell-mediated immune responses are important in limiting the duration of primary varicella infection. After primary infection, varicella is theorized to spread to mucosal and epidermal lesions to local sensory nerves. It then remains latent in the dorsal ganglion cells of the sensory nerves. The immune system keeps the virus in check. However, reactivation can still occur later in life, resulting in the clinically distinct syndrome of herpes zoster (shingles), postherpetic neuralgia, and sometimes Ramsay Hunt syndrome type II. Varicella zoster can harm the arteries in the neck and head, resulting in a stroke.

The United States Advisory Committee on Immunization Practices (ACIP) suggests that all adults older than 60 should get vaccinated to avoid herpes zoster. One in 5 adults who had chickenpox as children, especially those who are immune-suppressed, get singles. Shingles are most commonly found in adults over 60 diagnosed with chickenpox before age 1.[8][9]

History and Physical

The prodromal symptoms in adolescents and adults are aching muscles, nausea, decreased appetite, and headache, followed by a rash, oral sores, malaise, and a low-grade fever. Oral manifestations may precede the skin rash. In children, the illness may not be preceded by prodromal symptoms, and the initial sign could be a rash or oral cavity lesions. The rash begins as small red dots on the face, scalp, torso, upper arms, and legs. Over the next ten to 12 hours, it progresses to small bumps, blisters, and pustules, and eventually, umbilication and scabs formation. Of note is that the rash of chickenpox occurs in crops and is typically at different stages of evolution.

At the blister stage, intense pruritus is present. Blisters may occur on the palms, soles, and genital area. Commonly, visible evidence develops in the oral cavity and tonsil areas through small ulcers, which can be painful and itchy; this enanthem may precede the external exanthem by 1 to 3 days. These symptoms appear ten to 21 days after exposure. Adults may have a more widespread rash and longer fever, and they are more likely to develop pneumonia, the most important complication in adults.

Because watery nasal discharge containing live virus precedes exanthems by 1 to 2 days, the infected person is contagious 1 to 2 days before recognizing the disease. In most cases, the infection resolves itself within 2 to 4 weeks.

A common complication is a secondary bacterial infection that can present as cellulitis, impetigo, or erysipelas. Disseminated primary varicella is usually seen in immunocompromised individuals and carries high mortality. CNS complications are rare but may present as Guillain barre syndrome or encephalitis. Primary varicella infection during pregnancy can also affect the fetus, who may present later with chickenpox. In addition, the virus can potentially cause the varicella congenital syndrome.


The diagnosis of varicella infection is primarily based on the signs and symptoms. Confirmation is made by examination of the fluid within the vesicles, scraping of lesions that have not crusted, or by blood for evidence of an acute immunologic response. PCR has the highest yield and can be used for non-skin samples such as bronchoalveolar lavage and cerebrospinal fluid. Direct fluorescent antibody testing has largely replaced the Tzanck test. The vesicular fluid can also be cultured, but the yield is low compared to PCR. Blood tests identify a response to acute infection (IgM), previous infection, and subsequent immunity (IgG). Prenatal diagnosis of fetal varicella can be performed using ultrasound, though a delay of 5 weeks following primary maternal infection is advised. A PCR (DNA) test of the amniotic fluid can be performed. However, the risk of spontaneous abortion due to amniocentesis is higher than the risk of the baby developing fetal varicella.[10][11]

Treatment / Management

Treatment is symptomatic relief of symptoms. As a protective measure, those infected are usually required to stay home while infectious. Keeping nails short and wearing gloves may prevent scratching and reduce the risk of secondary infections.[12][13][1]

Topical calamine lotion may relieve pruritus. Daily cleansing with warm water helps avoid secondary bacterial infection. Acetaminophen may be used to reduce fever. Avoid aspirin as it may cause Reye syndrome. People at risk of developing complications and who have had significant exposure may be given intramuscular varicella-zoster immune globulin, a preparation containing high titers of antibodies to the varicella-zoster virus, to help prevent the disease.[14]

  • In children: Acyclovir decreases symptoms by 1 day if taken within 24 hours of the start of the rash. Still, it does not affect complication rates and is not recommended for individuals with normal immune function.
  • In adults, infection tends to be more severe, and treatment with antiviral drugs (acyclovir or valacyclovir) is advised if they can be started within 24 to 48 hours of rash onset. Supportive care, such as increasing water intake and using antipyretics and antihistamines, is important to management. Antivirals are typically indicated in adults, including pregnant women, because this group is more prone to complications. The preferred treatment is usually oral therapy, but intravenous antivirals are indicated for immunocompromised patients.

The varicella-zoster immunoglobulin is used to manage immunocompromised patients. In addition, a live attenuated vaccine has been available since 1995. There is high seroconversion following the vaccine, which is long-lasting. Adverse effects of the vaccine are rare.

Differential Diagnosis

The differential diagnoses for chickenpox include the following:

  • Insect bites
  • Impetigo
  • Smallpox
  • Drug eruptions
  • Dermatitis herpetiformis


The prognosis is excellent in healthy children. However, the infection has high morbidity in immunocompromised individuals.


Consultations that are typically requested for patients with this condition include the following:

  • Pediatrician
  • Infectious disease consultant

Pearls and Other Issues

Chickenpox is rarely fatal. Nonimmune pregnant women and those immunocompromised are at highest risk. Arterial ischemic stroke associated with childhood chickenpox is a significant risk. Varicella pneumonia is the most common cause of fatality in adults (10% to 30%), and in those requiring mechanical ventilation, this may reach 50%.

In pregnant women, antibodies from immunization or previous infection are transferred via the placenta to the fetus. Varicella infection in pregnant women could spread via the placenta and infect the fetus. If infection occurs during the first 28 weeks of pregnancy, congenital varicella syndrome may develop. Effects on the fetus can include underdeveloped toes and fingers, structural eye damage, neurological disorder, and anal and bladder malformation.

If maternal infection occurs 7 days before delivery and up to 8 days following birth, the baby may develop neonatal varicella with presentation ranging from mild rash to disseminated infection. Newborns who develop symptoms are at a high risk of pneumonia and other serious complications. Maternal herpes zoster, on the other hand, constitutes little risk of neonatal complications or congenital varicella syndrome, probably because of established circulating maternal antibodies.

Enhancing Healthcare Team Outcomes

Chickenpox is usually acquired after inhalation of aerosolized droplets from an infected individual. The majority of cases occur in children less than 10. The key to lowering the morbidity of chickenpox is education. Besides the primary caregiver, the nurse practitioner and pharmacist are vital in patient education. The parents of infected children should be told to trim the child's fingernails to avoid or minimize skin damage and associated bacterial infections. Further, parents should be told not to give aspirin to young children to control fever because of the risk of developing Reye syndrome. Finally, the parents should be told to apply cold compresses and moisturize the skin to prevent itching and dryness.[15][16][17] All clinicians should urge parents to get their children vaccinated because this can prevent the morbidity associated with the infection. The vaccine is safe and very effective. Immunocompromised children should be referred to an infectious disease specialist for further management. (Level V) Clinicians should also educate pregnant women who are seronegative for chickenpox to avoid contact with patients with an active infection. All pregnant women who develop chickenpox must be managed by a team of specialists who can make a treatment decision.


For most children who develop chickenpox, the outcome is excellent. However, in immunocompromised individuals, there is increased morbidity and mortality.[18][19][20]

Review Questions

Chickenpox (Varicella)


Chickenpox (Varicella). Chickenpox in an unvaccinated child. Public Health Image Library, Public Domain, Centers for Disease Control and Prevention


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Disclosure: Folusakin Ayoade declares no relevant financial relationships with ineligible companies.

Disclosure: Sandeep Kumar declares no relevant financial relationships with ineligible companies.

Copyright © 2024, StatPearls Publishing LLC.

This book is distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ), which permits others to distribute the work, provided that the article is not altered or used commercially. You are not required to obtain permission to distribute this article, provided that you credit the author and journal.

Bookshelf ID: NBK448191PMID: 28846365


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