Varicella-zoster infection (chickenpox)

This document contains the case definitions for Varicella-zoster infection (chickenpox) which is nationally notifiable within Australia. This definition should be used to determine whether a case should be notified.

Page last updated: 06 March 2018

Surveillance case definition

Version Summary of changes Last reviewed Implementation date
1.2
  • Addition of IgG seroconversion as laboratory definitive evidence
  • Removal of IgM detection as laboratory definitive evidence
2017 1 January 2018
1.1

No Change

14 August 2008 14 August 2008
1.0 Initial case definition 2006 2006

Reporting

Both confirmed cases and probable cases should be notified.

Confirmed case

A confirmed case requires either:

1. Laboratory definitive evidence AND clinical evidence

OR

2. Clinical evidence AND epidemiological evidence

Top of page

Laboratory definitive evidence

1. Isolation of varicella-zoster virus from a skin or lesion swab. If the case received varicella vaccine between five and 42 days prior to the onset of rash the virus must be confirmed to be a wild type strain.

OR

2. Detection of varicella-zoster virus from a skin or lesion swab by nucleic acid testing from a skin or lesion swab. If the case received varicella vaccine between five and 42 days prior to the onset of rash the virus must be confirmed to be a wild type strain.

OR

3. Detection of varicella-zoster virus antigen from a skin or lesion swab by direct fluorescent antibody from a skin or lesion swab. If the case received varicella vaccine between five and 42 days prior to the onset of rash the virus must be confirmed to be a wild type strain.

OR

4. IgG seroconversion or a significant increase in antibody level, such as a fourfold or greater rise in titre to varicella-zoster virus (VZV) EXCEPT if the case has received a VZV-containing vaccine eight days to eight weeks prior to convalescent specimen collection.  (NOTE: paired sera must be tested in parallel)

Clinical evidence

Acute onset of a diffuse maculopapular rash developing into vesicles within 24–48 hours and forming crusts (or crusting over) within 5 days.

Epidemiological evidence

An epidemiological link is established when there is:

1. Contact between two people involving a plausible mode of transmission at a time when:

a. one of them is likely to be infectious

AND

b. the other has illness 10 to 21 days after contact

AND

2. At least one case in the chain of epidemiologically-linked cases is laboratory confirmed.

Probable case

A probable case requires clinical evidence only.

Note: Laboratory confirmation should be strongly encouraged for vaccinated cases. If positive, samples should be referred for identification as a vaccine or wild type strain.

In this section