CHICKENPOX

A highly contagious viral infection. Patients are contagious from 2 days before onset of the rash until all lesions have crusted. An attack of chicken pox usually confers lifelong immunity. Disease is more severe and complicated in adults.

Causes

  • Varicella Zoster virus (VZV) by droplet infection

Clinical features

  • Incubation period is 14 days, but shorter in immunocompromised host
  • Mild fevers occur 10-20 days after exposure
  • Prodromal symptoms consisting of low fever, headache, and malaise occurring 2 to 3 days before the eruption
  • Eruptive phase: they appear as macules, papules, vesicles, pustules and crusts. The most characteristic lesion is a vesicle looking like a drop of water on the skin. Vesicles rupture easily and may become infected
  • The rash begins on the trunk and spreads to the face and extremities
  • Lesions of different stages (crops) exist together at the same time in any given body area
  • Complications may include septicaemia, pneumonia, fulminating haemorrhagic varicella, and meningoencephalitis

Differential diagnosis

  • Drug-induced eruption
  • Scabies
  • Insect bites
  • Erythema multiforme, impetigo
  • Other viral infections with fever and skin rash

Investigations

  • Virus isolation possible but not necessary
  • Diagnosis is practically clinical

Management

Symptomatic and supportive treatment

  • Apply calamine lotion every 12 hours
  • Cool, wet compresses to provide relief
  • Chlorpheniramine: Adult 4 mg every 12 hours
    Child <5 years: 1-2 mg every 12 hours for 3 days
  • Pain relief: paracetamol 10 mg/kg every 6 hours

In adults and children >12 years consider antivirals:

  • Oral aciclovir 800 mg every 6 hours for 7 days
  • Keep child at home/remove from school till healed to avoid spread

Prevention

  • Isolation of infected patient
  • Avoid contact between infected persons and immunosuppressed persons