Varicella (Chickenpox)

Introduction

Varicella Zoster virus is Human Herpes Virus. Its transmission is by direct contact with the lesions and by the respiratory route.
Initial replication occurs in the nasopharynx and conjunctivae.
After the primary infection, the virus remains dormant in nervous tissue
Reactivation later in life is typically manifested as Herpes zoster.

Symptoms and clinical features of chickenpox

  • Incubation period is 10-21 days
  • Vesicular eruptions consist of delicate “teardrop” vesicles on an erythematous base
  • The eruption starts with faint macules that develop rapidly into vesicles within 24 hours
  • Successive fresh crops of vesicles appear for a few days, mainly on the trunk, face, and oral mucosa
  • New lesions usually stop appearing by the fifth day; the majority is crusted by the sixth day
    • Most disappear in less than 20 days without a scar, except larger and secondarily infected lesions
  • Low grade fever
  • Malaise
  • Headaches

The severity of the disease is age-dependent

  • Adults have more severe disease and a greater risk of visceral disease.

Differential diagnoses

  • Variola minor
  • Disseminated zoster in immunosuppressed patients
  • Widespread papular urticaria
  • Coxsackie and ECHO viruses eruption

Complications of chickenpox

  • Secondary bacterial infection
  • Pneumonia
  • Cerebellar ataxia and encephalitis
  • Reye’s syndrome

Investigations

  • Tzanck smear
  • Direct fluorescent antibody (DFA) staining
  • Polymerase Chain Reaction (PCR)

Treatment for chickenpox

 Treatment objectives

  1. Relieve itching and treat secondary bacterial infection
  2. Reduce severity and scarring

Drug treatment

Aciclovir

  • Adult: 10 mg/kg intravenously three times daily for 7 days in immunocompromised patients
  • Child: see Herpes zoster

Antihistamine for pruritus

Co-trimoxazole or erythromycin for
secondary infection

Adverse drug reactions, caution

Aciclovir

  • Ensure adequate hydration
  • Caution in pregnancy and breastfeeding
  • May cause nausea, vomiting, dizziness, fatigue pruritus and photosensitivity

Prevention of chickenpox

  • To prevent chickenpox from spreading, isolate patients from non-immune persons.