Australian national notifiable diseases case definitions

Varicella-zoster infection (chickenpox)

This document contains the case definitions for Influenza which is nationally notifiable within Australia. This definition should be used to determine whether a case should be notified.

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Surveillance case definition

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

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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. Detection of varicella-zoster virus-specific IgM in an unvaccinated person.

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.