What is Chicken Pox?
Chicken Pox is a highly contagious viral infection caused by Varicella Zoster Virus (VZV). It is usually a mild disease in childhood.
It can be contracted from others with either Chicken Pox or Shingles.
What is Varicella Zoster Virus?
Varicella Zoster Virus (VZV) is a type of human herpesvirus.
Primary infection causes Varicella Zoster (Chicken Pox).
Secondary (reactivation) infection causes Herpes Zoster (Shingles).
Reference: Nelson’s Paediatrics (18th Edition), p 1366.
What is the natural course of Chickenpox?
VZV is transmitted by airborne spread or direct contact with respiratory secretions or the fluid of skin lesions for infected individuals.
Infective from 1-2 days before appearance of rash until vesicles are crusted (usually 3-7 days after onset).
- Primary infection of upper respiratory tract and tonsils
- Incubation period of 10-21 days
- Subclinical viraemia with spread to reticuloendothelial system
- Secondary viraemia with widespread rash lasting 3-7 days
- Peripheral blood mononuclear cells carry the virus
- In immunocompromised individuals, uninhibited replication of the virus may cause disseminated infection (lungs, liver, brain)
- Retrograde transport of virus through sensory neurons to dorsal root ganglia
- Reactivation of the virus causes Herpes Zoster (Shingles).
Reference: Nelson’s Paediatrics (18th Edition), p. 1366.
How does Chicken Pox present?
Prodrome
- Fever
- Malaise
- Anorexia
- Headache
- Mild abdominal pain
- Rash (pruritic macule > papule > clear vesicle > clouding > umbilication > crusting)
- Rash typically starts on scalp/face/trunk*
- Ulcerative lesions in mouth/vagina are common*
- Fever
How is Chicken Pox investigated?
Chicken Pox often does not need investigation, however, the following may be found:
Leucopaenia
Mildly elevated LFTs
VZV IgG (to check immunisation status)
How is Chicken Pox managed?
Supportive Measures
d
