varicella-zoster%20virus%20infection%20(pediatric)
VARICELLA-ZOSTER VIRUS INFECTION (PEDIATRIC)
Varicella, also known as chickenpox, is a self-limited, benign disease caused by primary varicella-zoster virus (VZV) infection characterized by fever, malaise, and generalized pruritic vesicular rash.
The average incubation period is 14-16 days. It is transmitted via direct contact with vesicular fluid or inhalation of aerosolized respiratory secretions or via droplet route during face to face contact.
Hallmark sign is pruritic rash that begins in the scalp and face which eventually spreads to the trunks and extremities.

Pharmacotherapy

Symptomatic Therapy

Antipruritics

  • Calamine lotion, tepid baths, cool compresses

Antipyretics

  • Eg Paracetamol
    • Aspirin should not be used in children because of its association with Reye’s syndrome
  • Provide symptomatic relief of fever

Analgesics

  • Eg Paracetamol, nonsteroidal anti-inflammatory drugs (NSAIDs); opioids may be considered in severe pain
  • May be used for relief of pain in herpes zoster infections

Corticosteroids

  • Benefits include acute pain reduction & rapid early healing
  • Should be administered with antiviral therapy due to its immunosuppressive properties
    • Concomitant use does not reduce incidence of postherpetic neuralgia (PHN)

Local Therapy for Herpes zoster Lesions

  • Eg saline solution, mild antiseptics (Polyhexanide solution, Zinc oxide lotion)
  • May be used for acute vesicular or necrotizing herpes zoster lesions

Antivirals for varicella

  • In otherwise healthy children, varicella is often benign & requires symptomatic care only
  • Varicella in otherwise healthy adolescents & in immunocompromised patients tends to be more severe & they may be treated with antivirals preferably within 24 hours
  • Considering that varicella is a self-limited disease, antivirals are not recommended for immunocompetentchildren ≤12 years of age; benefits should be weighed against adverse events & treatment cost

Aciclovir (PO/IV)

  • Aciclovir is recommended in VZV infections in immunocompromised patients
    • May be considered in patients with chronic cutaneous disorders, in patients w/ diseases that can be exacerbated by VZV infection (eg cystic fibrosis), otherwise healthy patients >12 years old or secondary household contacts, adolescents & adults
  • IV therapy should be used in severely immunocompromised patients & in severe infections
    • High-dose oral Aciclovir may be sufficient for mildly immunocompromised patients
  • Aciclovir is a guanosine analogue that is a competitive inhibitor of viral DNA polymerase
    • Limits viral replication & stops further spread of the virus to other cells
  • Shortens the duration of viral shedding, halts the formation of new lesions more quickly, accelerates the rate of healing in both immunocompetent & immunocompromised patients
    • This improvement is modest in the healthy individual but can reduce life-threatening complications in high-risk individuals

Famciclovir/Valaciclovir

  • Have been used in place of Aciclovir in otherwise healthy adolescents

Antivirals for herpes zoster

  • Eg Aciclovir, Brivudin, Famciclovir, Valaciclovir 
  • Antiviral therapy is recommended in immunocompetent patients with the following:
    • Ophthalmic, head and/or neck involvement
    • Any localization with moderate to severe zoster-associated pain, hemorrhagic/necrotizing lesions, involvement of >1 segment, aberrant vesicles/satellite lesions, or mucous membrane involvement
    • Patients ≥50 years old
    • Severe dermatologic disease (eg atopic dermatitis)
    • Pediatric patients on chronic salicylic acid or glucocorticoid therapy
  • Also recommended for patients <50 years old at low risk or without complications but with trunk or extremities involvement
  • Intravenous (IV) Aciclovir is typically recommended in those with or at risk for complicated herpes zoster:
    • Head &/or neck involvement
    • Hemorrhagic/necrotizing lesions, involvement of >1 segment, aberrant vesicles/satellite lesions, or mucous membrane involvement
    • Immunocompromised patients
    • Visceral or CNS involvement
  • Primary goal of treatment in herpes zoster is to reduce acute pain & PHN
  • Therapy for herpes zoster should accelerate healing; limit the severity & duration of acute & chronic pain; reduce complications
  • When taken within 72 hours of symptom onset, oral antivirals have been shown to reduce severity & duration of symptoms
    • Most virus replication has ceased by 72 hours after the onset of rash but this may be substantially extended in immunocompromised patients
    • After 72 hours, antivirals should be considered if new vesicular lesions are continuing to appear 
  • Choice of agent depends on availability, cost, dosing schedule & patient preference

Aciclovir

  • Guanosine analogue that is a competitive inhibitor of viral DNA polymerase
    • Limits viral replication & stops further spread of the virus to other cells
  • Several studies have shown that high-dose oral Aciclovir accelerates resolution of acute lesions & may reduce the risk for prolonged pain

Alternative Treatment for Herpes Zoster

Brivudine (Brivudin)

  • Actions: A thymidine nucleoside analogue that competitively inhibits viral DNA replication by blocking DNA polymerases
  • Brivudine is a treatment option for immunocompetent patients with herpes zoster
    • Recommended alternative to intravenous Acyclovir for patients with renal function impairment
  • Effects: Several studies have shown that patients given Brivudine had shorter time to last new-lesion formation & full crusting, & with less experienced pain
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