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Clinical features

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

Authoring team

Features include:

  • the incubation period is from 14 up to 21 days
    • chicken pox is infectious from a few days before the onset of rash develops and not more than six days after first lesions appear (1)
    • this period may be prolonged in immunocompromised patients (2)
    • chickenpox is very infectious - cases on a ward ought to be isolated to prevent cross infection
  • the rash begins as macular lesions which develop into papular, or vesicular lesions (filled with fluid) and later becomes pustular
  • chickenpox rash has a centripetal distribution - mostly on the face and trunk and sparsely on the limbs
  • there is erythema around the lesions and they are intensely itchy
  • usually the rash peaks at around 48 hours in immunocompetent people
  • vesicles dry and crust over, and sometimes scar if scratched to excess
  • oropharynx and genital tract mucous membranes may be involved as well
  • new lesions can emerge for up to 5 days (3)
  • a haemorrhagic rash may occur in immuno-suppressed patients

In children under 10 years, the disease is usually mild and self limiting, but a more severe infection can be seen in

  • adults - especially in pregnant women and in smokers since they are at an increased risk of developing fulminanting varicella pneumonia
  • neonates and immunosupressed individuals – there is an increased risk of developing disseminated or haemorrhagic varicella (2)

Signs of severe infections include:

  • respiratory symptoms (clinical respiratory signs are often absent).
  • densely cropping vesicles
  • haemorrhagic rash
  • bleeding from gums, haemoptysis, GI bleeding
  • any neurological changes - cerebellar signs, encephalopathy
  • persisting fever with new vesicles >6 days after onset (2)


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