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Chickenpox A004

Last amended 
6 July 2015
Current RMA Instruments:
Reasonable Hypothesis SOP 87 of 2015
Balance of Probabilities SOP  88 of 2015
Changes from previous instruments:

SOP Bulletin 184

 ICD Coding:
  • ICD-9-CM Codes: 052
  • ICD-10-AM Codes: B01
Brief description:

Chickenpox is an acute self-limiting viral infection by the Varicella-Zoster virus.  It manifests as a vesicular skin rash but can also produce systemic effects which can be serious such as pneumonia, or encephalitis.  The incubation period is between 10-21 days.  The virus is highly contagious.  Infectivity is generally considered to last from 48 hours prior to the onset of the rash until the skin lesions have fully crusted.  The condition can be more severe if contracted as an adult rather than as a child.

The reactivation of a quiescent latent infection is ‘Shingles’ and is not covered by this SOP but by the ‘Herpes Zoster’ SOP.  A claim of chicken pox should generally be determined as “Chicken pox – resolved”.

Confirming the diagnosis:

The diagnosis is typically made clinically, but can be confirmed by testing the vesicular fluid, or by serology.

The relevant medical specialist is an infectious disease physician.

Additional diagnoses covered by these SOPs
  • Varicella
Conditions not covered by these SOPs   
  • Herpes zoster*
  • Shingles*        (Herpes Zoster)

* another SOP applies  - the SOP has the same name unless otherwise specified

Clinical onset

The clinical onset is the earliest time prior to the confirmation of the disease, that the pathognomonic set of symptoms and signs could be documented.

Clinical worsening

There are no worsening factors except for inability to obtain appropriate clinical management.  Treatment is usually symptomatic only unless the patient is immunocompromised, or complications develop.  If clinical worsening is being considered an opinion from an infectious disease physician should be sought, on whether there has been a clinical worsening out of keeping with the natural history of the underlying pathology.