{
 "topic": "Herpes Zoster",
 "slug": "herpes-zoster",
 "category_id": 15809,
 "summary": "Reactivation of latent varicella-zoster virus causing a dermatomal vesicular rash, generally milder and less painful in children than adults, with distinct risk factors for early-childhood and immunocompromised cases.",
 "written_by": "claude-sonnet",
 "references": [
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   "author": "A. Carlson Merrow Jr. MD",
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 ],
 "short": [
  {
   "title": "In short",
   "content": "- Herpes zoster (shingles) is reactivation of latent varicella-zoster virus (VZV) from a dorsal root or extramedullary cranial nerve ganglion, where it has remained dormant since the primary varicella infection.\n- It is uncommon in healthy children under age 10; the exceptions are children who acquired VZV in utero or in the first year of life, who have an increased risk of zoster in early childhood.\n- Zoster is not caused by exposure to a varicella patient \u2014 in fact, re-exposure to varicella boosts cell-mediated immunity to VZV and lowers the chance of reactivation.\n- The lifetime risk of zoster after varicella is at least 30%, with 75% of cases occurring after age 45.\n- Presentation: burning pain, itching, or paresthesia followed by grouped vesicles on an erythematous base in a dermatomal distribution (usually 1-3 dermatomes), most often thoracic, cranial nerve (especially ophthalmic, V1), or lumbosacral; lesions increase in number over 3-5 days and crust by about 1-2 weeks.\n- Herpes zoster in otherwise healthy children is milder than in adults \u2014 less acute pain, minimal neuritis, resolution usually within 1-2 weeks \u2014 and postherpetic neuralgia is unusual/rare in children, unlike in adults where nearly half develop complications.\n- V1 (ophthalmic) dermatome involvement warrants ophthalmologic examination because of possible corneal/eye involvement; recurrent or multidermatomal shingles suggests an underlying primary or secondary T-cell immune defect.\n- Zoster occurs about 10 times more often in untreated HIV-infected children than in age-matched healthy children, and is also more common in children who had varicella in infancy (under 1-2 years old) or whose mother had varicella during pregnancy (especially the third trimester); lesions can be more generalized with visceral involvement in immunosuppressed patients.\n- The live-attenuated varicella vaccine can itself cause herpes zoster in immunocompetent children, though this is usually mild and occurs infrequently."
  }
 ],
 "long": [
  {
   "title": "Definition",
   "content": "Varicella-zoster virus (VZV) causes a primary infection (varicella/chickenpox) that establishes lifelong latency in sensory ganglionic neurons. Herpes zoster (shingles) is the clinical disease that results when this latent infection reactivates, causing inflammation of a dorsal root or extramedullary cranial nerve ganglion."
  },
  {
   "title": "Epidemiology",
   "content": "Herpes zoster is uncommon in childhood and shows no seasonal variation. The lifetime risk of zoster in someone with a history of varicella is at least 30%, with 75% of cases occurring after age 45. It is unusual in healthy children younger than 10, with a notable exception: children who acquired VZV in utero or during the first year of life carry an increased risk of zoster in the first few years of life. Zoster occurs about 10 times more frequently in untreated HIV-infected children than in age-matched healthy children, and is a common problem generally in HIV-infected or otherwise immunocompromised children. It can also occur, infrequently and usually mildly, in children who received the live-attenuated varicella vaccine."
  },
  {
   "title": "Etiology",
   "content": "Zoster results from reactivation of latent VZV rather than from external exposure \u2014 exposure to a patient with active varicella actually boosts cell-mediated immunity to VZV in a previously infected person and decreases the likelihood of reactivation. Risk factors for zoster specifically in children include acquiring varicella in early infancy (under 1-2 years old), intrauterine VZV exposure, and maternal varicella during pregnancy (particularly the third trimester). Immunosuppression, including HIV infection and immunosuppressive therapy, is a major risk factor at any age. Recurrent or multidermatomal shingles in a child suggests an underlying primary or secondary T-cell immune defect."
  },
  {
   "title": "Clinical features",
   "content": "Zoster typically begins with burning pain, itching, or paresthesia along the affected dermatome \u2014 a prodrome that, especially in older children, precedes the rash and, per one description, can include malaise, fever, headache, and dermatomal tenderness lasting 3 days or more. This is followed by closely grouped vesicles on an erythematous base, confined to one to three sensory dermatomes and not crossing the midline; lesions resemble a localized version of varicella or herpes simplex and often coalesce. The most commonly affected sites are the thoracic dermatomes and cranial nerve distributions, especially the ophthalmic (V1) branch of the trigeminal nerve; lumbosacral involvement also occurs. New lesions appear for 3-5 days, and crusting occurs over roughly 7-10 days (up to about 2 weeks). Compared with adults, zoster in otherwise healthy children is milder, less often associated with significant acute pain, hyperesthesia, pruritus, or low-grade fever, and symptoms of acute neuritis are minimal; complete resolution usually occurs within 1-2 weeks. In immunosuppressed patients, lesions may be more generalized, and visceral involvement can occur. When the trigeminal nerve's maxillary or mandibular divisions are involved, the oral cavity can show erosions."
  },
  {
   "title": "Diagnostics",
   "content": "Diagnosis is clinical, based on the hallmark dermatomal distribution of grouped vesicles on an erythematous base, evolving from discrete vesicles to coalesced lesions to a crusted stage. Ophthalmologic examination should be performed whenever the V1 (ophthalmic) dermatome is involved, given the possibility of corneal or other eye involvement. A Tzanck smear was historically used but is now considered of only historical value."
  },
  {
   "title": "Differential diagnosis",
   "content": "The dermatomal, unilateral distribution distinguishes zoster from primary varicella (chickenpox), which is diffuse rather than dermatomal, and from herpes simplex, which the grouped vesicles can otherwise resemble. In an immunocompetent child, cranial or peripheral nerve palsies in dermatomes affected by skin lesions suggest zoster, in contrast to other causes of viral encephalitis such as enterovirus (hand-foot-mouth disease produces vesicles on the hands, feet, elbows, knees, and lips rather than a dermatomal pattern)."
  },
  {
   "title": "Complications",
   "content": "Unlike in adults \u2014 where almost half develop complications, most often postherpetic neuralgia \u2014 postherpetic neuralgia is rare or unusual in children, and complications generally are infrequent in children. Roughly 4% of patients overall suffer a second episode of zoster; three or more episodes are rare. Ophthalmic (V1) zoster carries a risk of corneal involvement. Recurrent or multidermatomal disease should prompt evaluation for an underlying T-cell immune defect."
  },
  {
   "title": "Treatment",
   "content": "Varicella and herpes zoster can both be treated with antiviral drugs. Vaccines exist to help prevent both primary varicella and, in older adults, herpes zoster itself."
  }
 ],
 "clinical": [
  {
   "title": "Bedside recognition",
   "content": "Suspect herpes zoster in a child with grouped vesicles on an erythematous base confined to one to three dermatomes and not crossing the midline, especially over the thorax or a cranial nerve distribution, sometimes preceded by burning pain, itching, or paresthesia in that area. Ask about risk factors that raise suspicion and prognosis: varicella acquired in the first 1-2 years of life, intrauterine VZV exposure, maternal varicella during pregnancy, or immunosuppression (including HIV infection, where zoster is about 10 times more frequent than in healthy age-matched children). Perform an ophthalmologic examination whenever the ophthalmic (V1) branch of the trigeminal nerve is involved, because of the risk of corneal involvement. Recurrent or multidermatomal shingles should prompt evaluation for an underlying T-cell immune defect."
  },
  {
   "title": "Management and reassurance",
   "content": "In an otherwise healthy child, herpes zoster typically runs a mild course \u2014 lesions crust within about 1-2 weeks, acute neuritis is minimal, and postherpetic neuralgia is rare, unlike the pattern in adults. Antiviral drugs can be used to treat herpes zoster. In an immunosuppressed child, watch for more generalized lesions or visceral involvement, which is more common in that population. When the varicella vaccine itself is the cause of zoster in an immunocompetent child, reassure that this is usually a mild illness."
  }
 ]
}