{
 "topic": "Varicella Zoster",
 "slug": "varicella-zoster",
 "category_id": 15684,
 "summary": "Primary varicella-zoster virus infection (chickenpox) in children \u2014 its classic centrifugal crop rash, complications, congenital and neonatal forms, isolation requirements, and treatment.",
 "written_by": "claude-sonnet",
 "references": [
  {
   "title": "MedStudy Pediatrics Core 11th Edition 2024-2025",
   "author": null,
   "pages": [
    790
   ]
  },
  {
   "title": "Zitelli and Davis' Atlas of Pediatric Physical Diagnosis: Expert Consult - Online",
   "author": null,
   "pages": [
    495
   ]
  },
  {
   "title": "Kliegman R. Nelson Textbook of Pediatrics 2-Volume Set 22ed 2024",
   "author": null,
   "pages": [
    1351,
    2007,
    2008
   ]
  },
  {
   "title": "Pediatric Clinical Practice Guidelines & Policies, 18th Edition",
   "author": "American Academy of Pediatrics",
   "pages": [
    896
   ]
  },
  {
   "title": "Red Book Atlas of Pediatric Infectious Diseases",
   "author": "American Academy of Pediatrics (AAP);Tan, Tina Q.;",
   "pages": [
    824
   ]
  },
  {
   "title": "Gomella's Neonatology: Management, Procedures, On-Call Problems, Diseases, and Drugs, Eighth Edition",
   "author": "Tricia Lacy Gomella, Fabien G. Eyal and Fayez Bany-Mohammed",
   "pages": [
    1244,
    1245
   ]
  },
  {
   "title": "CURRENT Diagnosis and Treatment Pediatrics, Twenty-Fourth Edition",
   "author": "Hay, William W., Levin, Myron J., Deterding, Robin R., Abzug, Mark J.",
   "pages": [
    443
   ]
  },
  {
   "title": "Netters Pediatrics (Florin \u0422., Ludwig St.)",
   "author": null,
   "pages": [
    636
   ]
  }
 ],
 "short": [
  {
   "title": "In short",
   "content": "- Varicella-zoster virus (VZV) causes a primary infection (varicella/chickenpox), establishes lifelong latency in sensory ganglionic neurons, and can later reactivate as herpes zoster (shingles).\n- Classic varicella presentation: brief prodrome of low-grade fever, upper respiratory symptoms, and malaise, then a pruritic exanthem appearing in crops (usually about 3, range 1-5) that spreads centrifugally \u2014 starting on the trunk and scalp, then spreading peripherally; scalp lesions in the first crop help diagnose early disease.\n- Lesions evolve rapidly: tiny erythematous papules enlarge into thin-walled superficial vesicles with a red halo (\"dew drop on a rose petal\"), the fluid clouds, then the lesion dries and umbilicates; different stages (papule, vesicle, pustule, crust) are present simultaneously \u2014 a total of roughly 250-500 lesions with a low-grade fever and possible other systemic symptoms.\n- Incubation period is 10-21 days by direct/airborne spread; a child with varicella is infectious and needs isolation until all lesions are crusted, or for a minimum of 5 days if crusting occurs earlier. In healthcare settings, an exposed susceptible person needs airborne/contact precautions in a negative-pressure room from days 8-21 after exposure (up to 28 days if they received varicella-zoster immune globulin).\n- Breakthrough varicella (in vaccinated children) is usually milder and more atypical, requiring a high index of suspicion.\n- Complications of primary varicella include bacterial superinfection (especially staphylococcal and group A streptococcal), pneumonia, encephalitis, bleeding disorders, and, in the fetus/neonate, congenital infection or life-threatening perinatal infection.\n- Fetal varicella syndrome (congenital varicella syndrome) follows maternal varicella in the first half of pregnancy (highest risk between about 8-20 weeks gestation, incidence roughly 1-2%); features include limb hypoplasia, cutaneous scarring, eye abnormalities, and CNS damage, and children infected in utero can develop zoster early in life without ever having extrauterine varicella.\n- Diagnosis is usually clinical, confirmed if needed by PCR or direct fluorescent antibody of vesicular fluid/scab, viral culture (3-4 days), or a fourfold rise in VZV IgG; expect early leukopenia followed by lymphocytosis and mildly elevated liver enzymes.\n- Acyclovir (or valacyclovir) is not routinely recommended for healthy children with varicella but is used for adolescents, unvaccinated children 12 years or older, those with chronic skin or lung disease, and immunocompromised children; supportive care suffices in the healthy host."
  }
 ],
 "long": [
  {
   "title": "Definition",
   "content": "Varicella-zoster virus (VZV) causes primary, latent, and reactivation infections. The primary infection manifests as varicella (chickenpox) and establishes lifelong latent infection of sensory ganglionic neurons; reactivation of that latent infection causes herpes zoster (shingles)."
  },
  {
   "title": "Epidemiology",
   "content": "Varicella was a common acute febrile rash illness in US children before universal childhood vaccination. Only about 5% of women of childbearing age remain susceptible to VZV. Varicella during pregnancy is estimated to occur in 1 to 5 per 10,000 pregnancies. Although varicella can rarely spread in settings like sports through airborne transmission, such reports are uncommon in the vaccine era. Breakthrough varicella occurs in some vaccinated children, generally presenting more mildly and atypically than wild-type infection."
  },
  {
   "title": "Etiology",
   "content": "VZV spreads by airborne transmission or direct contact, with an incubation period of 10-21 days. Although generally a mild illness of childhood, varicella can cause substantial morbidity and mortality even in otherwise healthy children, with higher morbidity and mortality in immunocompetent infants and adolescents, adults, and immunocompromised persons. Varicella predisposes to severe group A streptococcal and staphylococcal infection. Primary disease is prevented by the live-attenuated varicella vaccine."
  },
  {
   "title": "Clinical features",
   "content": "Varicella in a normal host is relatively benign but highly contagious. A brief prodrome of low-grade fever, upper respiratory symptoms, and mild malaise may precede a pruritic exanthem that appears in crops, evolving over several hours; most children have about three crops (range one to five). Early crops appear on the trunk and scalp, with later crops distributed more peripherally \u2014 a centrifugal spread pattern \u2014 and scalp lesions accompanying the first crop are a helpful early diagnostic clue. Lesions progress from tiny erythematous papules to thin-walled superficial vesicles surrounded by a red halo (\"dew drop on a rose petal\"), with vesicular fluid clouding before the lesion dries and umbilicates; papules, vesicles, pustules, and crusts are present simultaneously across the body. Overall, a generalized pruritic vesicular rash of about 250-500 lesions in different stages of development, plus low-grade fever and possible other systemic symptoms, is typical."
  },
  {
   "title": "Diagnostics",
   "content": "Diagnosis is usually made from the typical clinical picture together with an exposure history. When confirmation is needed, options include PCR or direct fluorescent antibody testing of vesicular fluid or scab scraping, VZV-specific viral culture (results in 3-4 days), or demonstrating a significant (fourfold) rise in serum VZV IgG between acute and convalescent samples. Laboratory findings often include an initial leukopenia followed by lymphocytosis, with mildly elevated liver enzymes. For suspected congenital VZV infection, proof includes detection of viral DNA by PCR in the infant, VZV-specific IgM, persistence of VZV IgG beyond 7 months of age, or the appearance of zoster in early infancy."
  },
  {
   "title": "Differential diagnosis",
   "content": "Varicella and herpes simplex lesions undergo the same evolution \u2014 papule, vesicle, pustule, crust, and sometimes a slightly depressed scar \u2014 so the two can resemble each other; varicella is distinguished by lesions appearing in successive crops with many stages present at once, in contrast to herpes zoster's grouped, dermatomal distribution, usually on the trunk or face, which may not be painful and typically follows a mild course in children."
  },
  {
   "title": "Complications",
   "content": "Complications of varicella include bacterial superinfection (especially staphylococcal and group A streptococcal), pneumonia, encephalitis, and bleeding disorders. Fetal varicella (congenital varicella) syndrome follows maternal VZV infection in the first half of pregnancy and is a recognized teratogenic effect \u2014 VZV crosses the placenta to cause a pattern of congenital malformation including limb hypoplasia, cutaneous scarring in a dermatomal distribution, eye abnormalities, and central nervous system damage. The incidence of embryopathy/fetopathy after maternal infection in the first 20 weeks is about 1-2%, with highest risk when infection occurs between 8 and 20 weeks of gestation; rare cases have been reported after infection as late as 28 weeks. Children infected with VZV in utero can develop zoster early in life even without a history of extrauterine varicella. Separately, maternal varicella occurring from 5 days before to 2 days after delivery can cause severe, often fatal neonatal disease. Some immunocompromised hosts can develop VZV disease causing pneumonitis, encephalitis, and CNS vasculitis, for which avoiding live viral vaccines and providing antiviral prophylaxis appear prudent, though a defined treatment protocol does not exist."
  },
  {
   "title": "Treatment",
   "content": "Supportive care is sufficient for varicella in a healthy child, and acyclovir is not currently recommended routinely for this group. Acyclovir (or valacyclovir) treatment is used for adolescents, unvaccinated children 12 years and older, children with chronic skin or pulmonary disease, and immunocompromised or chronically treated children; these antivirals reduce disease duration and, when used for zoster, reduce the risk of postherpetic neuralgia. A child with varicella is considered infectious and should remain in isolation until all lesions have crusted, or for a minimum of 5 days if crusting occurs earlier. In a healthcare setting, a susceptible person with a history of exposure requires airborne and contact precautions in a negative-pressure room from days 8 to 21 after exposure, extended to 28 days if they received varicella-zoster immune globulin."
  }
 ],
 "clinical": [
  {
   "title": "Recognizing and confirming varicella at the bedside",
   "content": "Suspect varicella in a child with a brief prodrome of low-grade fever and malaise followed by a pruritic rash appearing in successive crops \u2014 typically about three \u2014 spreading centrifugally from the trunk and scalp outward, with lesions at multiple stages (papule, vesicle with a red halo, cloudy fluid, crust) present simultaneously. Diagnosis is usually clinical with an exposure history; if confirmation is needed, use PCR or direct fluorescent antibody of vesicular fluid or a scab scraping. In a vaccinated child, keep breakthrough varicella in mind if the rash looks milder or atypical. Expect an initial leukopenia followed by lymphocytosis and mildly elevated liver enzymes if labs are drawn."
  },
  {
   "title": "Isolation, treatment, and high-risk exposures",
   "content": "Keep a child with varicella in isolation until all lesions have crusted, or a minimum of 5 days if crusting is earlier; in a healthcare setting, place an exposed, susceptible contact under airborne and contact precautions in a negative-pressure room from days 8-21 after exposure (up to 28 days if they received varicella-zoster immune globulin). Supportive care is adequate for a healthy child; reserve acyclovir/valacyclovir for adolescents, unvaccinated children 12 years or older, those with chronic skin or lung disease, and immunocompromised children, since these agents shorten disease duration. Ask about the timing of any maternal varicella exposure during pregnancy or around delivery: infection in the first half of pregnancy (especially 8-20 weeks) raises concern for fetal varicella syndrome (limb hypoplasia, dermatomal skin scarring, eye disease, CNS damage), while maternal varicella from 5 days before to 2 days after delivery risks severe, potentially fatal neonatal disease and needs urgent neonatal assessment."
  }
 ]
}