Chicken pox

Chickenpox is a highly contagious viral rash caused by Varicella zoster virus, spready by airborne respiratory droplets or by contact with the vesicular fluid.

After contact with an infected individual, the incubation period lasts between 10 to 21 days, most commonly 14 days. It presents with a non-specific prodrome of flu-like symptoms, fever and lethargy. After 3 to 5 days crops of small papules develop that rapidly turn into vesicles and then crust over. At any one point the rash will have mixed papules, vesicles and crusting. Once all the lesions have crusted over (usually about 10 days) it is no longer contagious. The lesions typically present on the scalp, face and trunk, although it is possible to develop them anywhere on the body. Ophthalmic review is recommended if conjunctival lesions are suspected.

Generally a benign illness, some individuals are more at risk:

  • Pregnant women – serology (IgM and IgG is used to determine the need for immunisation and treatment)
  • Neonates
  • Immunocompromised children

Treatment algorithms are therefore in place for individuals in these groups who are either exposed or develop chickenpox to modify the illness.

  • Adolescents and adults are more likely to have a more severe illness course and develop complications and therefore may be treated with oral acyclovir if present early in the disease.

Complications include:

  • Bacterial superinfection
  • Viral pneumonia
  • Encephalitis
  • Cerebellitis
  • Hepatitis
  • Arthritis
  • Reye syndrome
  • Guillain-Barre syndrome
  • Thrombocytopenia

Treatment is supportive including oral / IV hydration, moisturisers and antihistamines plus consideration of acyclovir in adolescents over the age of 12.

Controversy exists around the use of NSAIDs in chickenpox. Read the DFTB blog below to find out more about this topic.

Once infected with varicella, generally an individual is immune for life, unless immunocompromised. Herpes zoster (shingles) is due to reactivation of the varicella virus from nerve roots. This rash presents in a dermatomal distribution in adults, but in children may spread over more than one dermatome.