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chickenpox

Etiology: 1) primary infection with Varicella zoster virus 2) immunosuppression (including systemic steroids) increases susceptibility [2] Pathology: 1) incubation 10-20 days 2) infectivity a) begins 48 hours prior to onset of symptoms b) persists through period of new lesion formation (3-5 days) Epidemiology: 1) no gender or race predilection 2) seasonal peak late winter, early spring 3) generally affects children 4) transmitted via airborne respiratory droplets or direct vesicle contact [8] Clinical manifestations: 1) prodrome of low-grade fever, malaise & pharyngitis [6] may precede rash by 24-48 hours 2) 1st lesions generally appear as erythematous vesicles on trunk &/or face 3) lesions appear in crops such that lesions in different phases of development are present at any one time 4) lesions spread centripetally to involve entire skin surface & possibly mucous membranes 5) rash is vesiculopapular a) new clear vesicles 3-5 mm in diameter on an erythematous base, described as dewdrop on a rose petal b) older cloudy vesicles may progress to pustules or crusted papules c) multiple stages of lesions present at the same time,* i.e. a mix of vesicles, papules, pustules, crusted erosions, scabs d) new lesions cease appearing in 3-7 days 6) lesions are pruritic 7) scratching may result in excoriations &/or cellulitis 8) constitutional symptoms occur at the same time as rash* a) low-grade fever (100-103 F) b) myalgias c) headaches 9) symptoms may be more severe in elderly or immunocompromised patients 10) images [7] * distinguishing features from smallpox Laboratory: 1) diagnosis generally clinical, no laboratory tests usually required 2) Varicella-zoster virus DNA is test of choice [3] 3) serology a) acute & convalescent varicella serum titers b) ELISA or DFA 4) Tzanck smear 5) tissue culture 6) skin biopsy 7) gram stain or bacterial cultures of superinfected lesions 8) see ARUP consult [4] Differential diagnosis: 1) atypical presentation of measles 2) impetigo 3) Herpes simplex virus 4) enterovirus, especially coxsackie A 5) smallpox: a) fever precedes rash by 2-3 days b) rash is in the same stage in different locations at any one time, i.e. all vesicles, all papules, all pustules, all scabs Complications: 1) aspirin use during varicella infection in children may result in Reye syndrome 2) complications more common in elderly & immunocompromised a) pneumonia b) nephritis c) myocarditis d) arthritis e) meningitis f) encephalitis g) transverse myelitis h) optic neuritis i) cellulitis j) thrombotic thrombocytopenic purpura (TTP) k) purpura fulminans Management: 1) symptomatic treatment generally sufficient a) good hygiene b) anti-pruritics - calamine or other topical anti-pruritic agents - oral antihistamines - diphenhydramine (Benadryl) - children: 5 mg/kg/day PO divided every 6 hours - adults: 25-50 mg PO TID-QID - hydroxyzine (Atarax) - children: 2 mg/kg/day PO divided every 6 hours - adults: 25-200 mg PO TID-QID c) control fever with acetaminophen (Tylenol): DO NOT USE ASPIRIN! 2) Antiviral therapy for patients with complications & high-risk patients a) children 2-12 years: acyclovir (Zovirax) 20 mg/kg QID for 5 days (max 800 mg/day) b) adults & children > 12 years of age: acyclovir 800 mg PO 5 times/day for 7 days c) immunocompromised: IV acyclovir 10 mg/kg IV every 8 hours for 7-10 days 3) Quarantine until all lesions heal to minimize transmission 4) patient education a) reassurance: chickenpox is generally benign & self-limited b) AVOID USE OF ASPIRIN! c) inform family & close contacts of probable secondary outbreaks of chickenpox, including incubation period 5) prevention a) consider prophylaxis for immunocompromised & others - VZV immune globulin for up to 96 hours after exposure - prevents or lessens severity of infection in otherwise healthy, non-pregnant, susceptible adults [3] b) isolation for hospitalized patients & for hospital workers through the infectious period c) Varicella immunization (Varivax) recommended for all individuals who have not had chicken pox - children 1-12 years of age: 0.5 mL Varivax SQ - children 12-15 months with a 2nd dose at 4-6 years [3] - adults & children > 12 years of age: two 0.5 mL doses of Varivax SC 4-8 weeks apart - vaccinated individuals can still develop chicken pox, but their clinical course is usually milder than in unvaccinated patients [6] 6) chickenpox is a reportable disease

Related

Herpes zoster (shingles) varicella virus vaccine (Varivax) Varicella [Herpes] zoster virus (VZV); human herpesvirus 3 (HHV3)

General

Herpes virus infection

References

  1. Saunders Manual of Medical Practice, Rakel (ed), WB Saunders, Philadelphia, 1996, pg 864-67
  2. Prescriber's Letter 10(10):56 2003
  3. Medical Knowledge Self Assessment Program (MKSAP) 14, 15, 16, 18, 19. American College of Physicians, Philadelphia 2006, 2009, 2012, 2018, 2021. - Medical Knowledge Self Assessment Program (MKSAP) 19 Board Basics. An Enhancement to MKSAP19. American College of Physicians, Philadelphia 2022
  4. ARUP Consult: Varicella-Zoster Virus - VZV The Physician's Guide to Laboratory Test Selection & Interpretation https://www.arupconsult.com/content/varicella-zoster-virus
  5. Bond D, Mooney J. A literature review regarding the management of varicella-zoster virus. Musculoskeletal Care. 2010 Jun;8(2):118-22. PMID: 20301227
  6. NEJM Knowledge+ May 12, 2015 - Heininger U, Seward JF Varicella. Lancet. 2006 Oct 14;368(9544):1365-76. PMID: 17046469 - Baxter R, Tran TN, Ray P et al Impact of vaccination on the epidemiology of varicella: 1995-2009. Pediatrics. 2014 Jul;134(1):24-30 PMID: 24913796
  7. Brady MP (images) Cutaneous and Mucosal Manifestations of Viral Diseases. Medscape. March 2017 http://reference.medscape.com/features/slideshow/viral-skin
  8. Grimm L 14 Rashes You Need to Know: Common Dermatologic Diagnoses. Medscape. October 19, 2017 https://reference.medscape.com/slideshow/skin-rashes-6004772 - Papadopoulos AJ, Elston DM Chickenpox. Practice Essentials. Medscape. April 14, 2017 https://emedicine.medscape.com/article/1131785-overview