Chickenpox (Varicella, Herpes Zoster)
Chickenpox (Varicella, Herpes Zoster): Excerpt from The 5-Minute Pediatric Consult
Barbara M. Watson, MB, CHB, DCH, MRCP
Chickenpox - BASICS
Chickenpox - description
Varicella-zoster virus (VZV) is a herpesvirus. Only 1 strain is recognized.
Chickenpox - general prevention
Since 1995 varicella has been a vaccine-preventable disease and it has been incorporated in the harmonized immunization schedule recommended by the American Academy of Pediatrics (AAP) and American Committee on Immunization Practices (ACIP) since 1995, and is covered by the Vaccines for Children Program.
- The vaccine is recommended for routine immunization of all healthy susceptible children, adolescents, and adults.
- 1 dose (0.5 mL subcutaneously) is required for children 12 months to 13 years of age.
- As of June 2007, this is changed to 2 doses, the 1st routine dose at 12–15 months of age and the 2nd at 4–6 years of age. Use of the new combination vaccine measles, mumps, rubella, varicella is preferred.
- Individuals >13 years require 2 doses, 1–2 months apart.
- The vaccine is safe, with a <4% rash rate from immunization. Postlicensure surveillance has documented 3 incidences of transmission in >25 million doses. Rashes are unusual with 2nd doses.
- Duration of immunity from individuals followed in the clinical trials has shown that both humoral and cell-mediated immune responses persist for at least 10 years (US data) and 20 years (Japanese data), respectively. However, active and passive varicella surveillance data have in the last 12 years as nationwide coverage of vaccination improved, and there is decreased circulation of the virus that with 1 dose of vaccine has ~80% efficacy and hence has proved inadequate and outbreaks of varicella in vaccinated individuals have continued in elementary and high schools.
- The vaccine is not currently recommended for immunocompromised individuals, but there are studies in process, and HIV-positive children whose CD4 level is 15% of normal value should get 2 doses of vaccine 1–3 months apart.
- Vaccine is available by protocol for acute lymphatic leukemia in remission (tel.: 215-283-0897).
- For those individuals who cannot receive VZV vaccine because of an immunocompromised state, varicella-susceptible pregnant women (until the VZV vaccine registry has data to make alternate recommendations), and newborns, VZIG has been discontinued, but Varicella Zoster Immune Globulin (VariZIG) can be obtained by calling the CDC VZV branch for use on an IND protocol from the FDA.
- Varicella vaccine is recommended for postexposure prophylaxis within 5 days of a household exposure, or if an outbreak in a school is identified, as soon as the local health authorities notify the parents. 2nd doses of Varicella vaccine should be given to susceptible children (who have only had 1 dose) in an outbreak setting.
Chickenpox - epidemiology
- Person-to-person transmission occurs by direct contact with varicella or zoster and respiratory secretions.
- Varicella is most common during late winter and early spring, but seasonality is now less pronounced.
- The introduction of an index case of varicella into a home results in transmission of the virus to susceptible persons and secondary cases of disease in 87–98% of susceptible persons:
- Secondary cases in this situation usually have more severe disease.
- Most reported cases occur between the ages of 5 and 9 years, although in areas of the US, where many 1–4-year-olds are in daycare, this age group predominates with an increase in complications. Since 2002, regions where vaccine coverage is >80% have experienced increasing numbers of adolescents and adults with varicella secondary to having not been vaccinated and remaining susceptible.
- Immunity from natural disease is usually lifelong, but symptomatic reinfections do occur; more common are asymptomatic reinfections, with a 4-fold boost in antibody level. The 2nd dose of vaccine boosts titers 12-fold to levels seen after natural disease.
- Immunocompromised individuals with either primary varicella or zoster are at risk for severe disease.
- Disease is also more severe in infants >3 months, adolescents, adults, persons on oral and/or IV steroids or long-term aspirin therapy, or persons with pulmonary disorders including asthma.
- Congenital varicella syndrome risk is about 2% and is greatest from the 12th to the 20th week of gestation.
- Incubation 10–21 days after contact; cases most contagious 2 days before the rash appears and until 5 days after lesions stop cropping (longer in immunocompromised patients)
- In varicella-active surveillance sites, breakthrough varicella or reinfection with varicella now represents 62% of all reported varicella cases. These rashes are atypical of varicella, are of shorter duration, usually have fewer lesions, are usually itchy, come in crops, and scab. Individuals with >50 lesions have been shown to transmit disease; however, it is less contagious (30%) than natural VZV (87%). When the diagnosis is in doubt; it may be verified by either polymerase chain reaction (PCR) of the lesion and/or acute and convalescent serum IgG showing a rise in titer. Only wild-type varicella has been identified from these confirmed cases of reinfection (breakthrough) VZV. Using these diagnostic tests, the Centers for Disease Control and Prevention (CDC) Varicella Active Surveillance Project in Philadelphia has demonstrated that 50% of what physicians thought might be a VZV reinfection is not.
Chickenpox - DIAGNOSIS
Chickenpox - signs & symptoms
Chickenpox - history
- Time of year: More common in winter and spring, but this seasonality is now less pronounced.
- Typical rash that has multiple stages identified: Classic finding
- Does a history of not previously having had varicella usually make the diagnosis? No: Recent studies have led the CDC to recommend that physicians disregard a history of varicella in US individuals born after 1980.
Chickenpox - physical exam
- The appearance of a typical rash that occurs in successive crops of macules, papules, and vesicles is distinctive; crops usually appear every 3 days.
- Vesicles may appear in the mouth, conjunctiva, vagina, and urethra.
- Some lesions may be secondarily infected.
Chickenpox - tests
Chickenpox - lab
- Immunofluorescence of the vesicular fluid
- Culture of the vesicular fluid
- PCR of any tissue of vesicular fluid (reference labs include Dr. Philip LaRussa, NY, and Dr. Scott Schmid, CDC National Viral Hepatitis, Atlanta, GA, dss1@cdc.gov).
- The complement-fixation test is not reliable in determining immunity and has been abandoned.
- Acute and convalescent sera for antibody testing by a number of assays, including enzyme immunoassay (EIA), immunofluorescence assay (IFA), latex agglutination (LA), fluorescent antibody to membrane antigen (FAMA), and, through the CDC laboratory group, ELISA (enzyme-linked immunosorbent assay), which is important in determining vaccine immunity:
- These tests can also be used to determine immunity.
- The whole-cell EIA is better for immunity from “wild/natural” diseases.
- The latex agglutination in commercial laboratories is not recommended for screening health care workers.
Chickenpox - differencial diagnosis
With limited or mild rash, the differential diagnosis includes other causes of vesiculation such as the following:
- Coxsackie virus infection with hand, foot, and mouth disease
- Rickettsial pox
- Mycoplasma
- Pseudomonas (in immunocompromised individuals)
- Eczema herpeticum
- Herpes zoster with dissemination
- Toxic epidermal necrosis and various noninfectious vesicular conditions of the skin
- Scabies
- Insect bites
- Impetigo
Chickenpox - TREATMENT
Chickenpox - general measures
Isolation of hospitalized patients:
- Strict isolation for the duration of vesicular eruption (usually 5 days, longer in immunocompromised patients)
- Patients should be in negative-pressure rooms if possible.
- Exposed susceptible persons should be in strict isolation for 8–21 days after the onset of the rash in the index patient.
- Persons who received varicella zoster immune globulin (VariZIG) should be kept in isolation for 28 days after exposure.
- Immunocompromised patients who have zoster (localized or generalized) and healthy patients with disseminated zoster should remain in strict isolation for the duration of the illness. For healthy patients with localized zoster drainage and secretion, precautions are recommended until all lesions are crusted. Do not send zoster patients back to school. Outbreaks of varicella have occurred secondary to zoster in school settings (publication pending).
- Anti-virals such as acyclovir, famvir, or valacyclovir may be prescribed to shorten the duration of the rash and shedding to others.
Chickenpox - medication
Acyclovir, vidarabine, famciclovir (Famvir), foscarnet, and a number of antiviral agents—pending licensure—have been shown in clinical trials to be effective against VZV.
- Acyclovir is the drug of choice in children (approved by FDA).
- Who benefits? Any child who is ill enough to warrant hospitalization and whose rash demonstrates new vesicle formation should be treated with acyclovir (IV dose is 1,500 mg/m2 divided into 3 doses q8h). Including in vaccinated children because of primary vaccine failure
- Consider oral acyclovir (80 mg/kg divided in 4 doses q6h) for children >12 years, those with chronic cutaneous or pulmonary disorders, persons on short or intermittent corticosteroids or aerosolized corticosteroids, newborn infants, and selected immunocompromised persons at risk for severe varicella.
- Children with varicella should not receive salicylates because of the association with Reye syndrome. Acetaminophen may be used to control the fever. NSAIDs may increase complications from bacterial superinfection.
- In the era of a preventable disease, acyclovir should be considered before complications of varicella warrant hospitalization.
Chickenpox - FOLLOW UP
Chickenpox - prognosis
- 50–100 previously healthy children used to die each year (1 or 2 each week) from varicella. The impact of the universal varicella vaccination program has been that this has now been reduced to 4 deaths in 2001 (the last complete year for which statistics are available).
- For most children, this childhood exanthem is a benign disease that lasts 6–8 days.
Chickenpox - complications
These complications are associated with significant morbidity and may occur regardless of the use of acyclovir:
- Secondary bacterial infection—especially virulent group A streptococcal infections and staphylococcal (drug resistance, an increasing problem)
- Varicella pneumonitis (more common in adults and infants)
- Gastrointestinal complications associated with viscous involvement, such as pancreatitis, appendicitis and hepatitis, idiopathic thrombocytopenia (ITP), and bleeding diathesis
- Nephritis
- Transverse myelitis
- Encephalitis, 60 cases per year pre–VZV vaccination
- Disseminated intravascular coagulation (hemorrhagic VZV)
- Individuals with AIDS may have chronic VZV.
- Arthritis, which can become superinfected usually with Staphylococcus aureus
- Congenital varicella syndrome that occurs in the first or second trimester of pregnancy, characterized by limb atrophy and scarring of the extremity. Central nervous system and eye manifestations also occur.
- Death: 1–2 deaths per week in the US; between 1990 and 1994 varicella was the most common vaccine-preventable cause of death in individuals <20 years. However, the impact of the universal immunization program has reduced this to 4 in the year 2001.
Chickenpox - patient monitoring
- In the postvaccine era, accurate diagnosis of “breakthrough/reinfection varicella” chickenpox varicella occurring >42 days after vaccine is crucial as it may point to lowered efficacy of improperly stored and administered VZV vaccine. Accurate diagnosis of VZV vaccine strain is made by sending a PCR specimen to the CDC (e-mail dss1@cdc.gov for instruction or telephone 404-639-0066).
- For normal healthy individuals, follow-up is not necessary.
Chickenpox - bibliography
- Arvin AM. Cell-mediated immunity to varicella-zoster virus. J Infect Dis. 1992;166(suppl 1):S35–S41.
- Meyer P, Seward J, Jumaan A, et al. Varicella mortality: Trends before vaccine licensure in USA 1970–1994. J Infect Dis. 2000;182:383–390.
- Seward JF, Watson B, Petersen C, et al. Varicella disease after introduction of varicella vaccination in the United States, 1995–2000. JAMA. 2002;287:606–611.
- Watson B. Varicella: A vaccine preventable disease—a review. J Infect. 2002;1–6.
ACIP recommendation Prevention of varicella June 22, 2007. http://www.cdc.gov/mmwr/preview/mmwr.html/rr5604a.htm.
Chickenpox - CODES
Chickenpox - icd9
- 052.9 Varicella without mention of complication
- V05.4 Varicella
Chickenpox - FAQ
- Q: What do you do for a patient on corticosteroids who has not had VZV and is exposed to VZV?
- A: These patients are immunosuppressed (if the dose of steroids is >0.2 mg/kg/d) and require VariZIG or treatment with acyclovir within 72 hours of developing VZV, if VariZIG had not been administered.
- Q: What about asthmatic patients on inhaled steroids? Can they be immunized safely, and are they at risk of more severe varicella if not immunized?
- A: Asthmatics on inhaled steroids can be immunized because the dose of inhaled steroids is not immunosuppressive. Recent data show that asthmatic children who are unimmunized do get more severe varicella.
- Q: Is there any patient who should not receive VZV vaccine?
- A: Yes. Immunosuppressed individuals, pregnant patients, and infants <1 yr old.
- Q: How contagious is breakthrough (reinfections) varicella disease?
- A: Surveillance studies have demonstrated that the secondary attach rate from breakthrough (reinfections) varicella is 30% in individuals with >50 lesions. Hence, when such individuals can expose high-risk susceptible patients in health care settings, infection control precautions should be observed. Public health investigation of outbreaks has also demonstrated transmission of varicella from vaccinated individuals to high-risk susceptible individuals (such as those with acute lymphocytic leukemia [ALL], transplant recipients, or students with HIV).
- Q: If a child gets zoster, with wild-type or vaccine strain, should she or he be treated with antiviral drugs?
- A: Surveillance studies have demonstrated that adolescents and children who develop herpes zoster have more pain and hospitalizations due to secondary infection than those with vaccine strain. In the future, laboratory testing for VZV strain is likely to be recommended. Also, treatment of herpes zoster in children (just as has been demonstrated in adults) shortens the course of illness and, more importantly, in school-aged children, decreases shedding. Since active surveillance has demonstrated that herpes zoster cases are the index cases in outbreaks, it makes public health sense to apply the lessons learned in adult herpes zoster to herpes zoster of children who are going back to school—i.e., put them on antivirals.
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Book Source Details
- Book Title: The 5-Minute Pediatric Consult
- Author(s): M. William Schwartz MD; et al.
- Year of Publication: 2008
- Copyright Details: The 5-Minute Pediatric Consult, Copyright © 2008 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: The 5-Minute Pediatric Consult
Authors: M. William Schwartz MD; et al.
Publisher: Lippincott Williams & Wilkins
Copyright: 2008
ISBN: 0-7817-7577-9
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