Smallpox case definition

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

Page last updated: 01 July 2019


Summary of changes

Last reviewed

Implementation Date


Initial case definition




  • Removal of ‘credible’ and addition of ‘syndrome consistent with’.
  • Addition of a footnote under clinical evidence.
  • Additional detail to epidemiological links.


1 July 2019


Both confirmed cases and probable cases should be notified.

Confirmed case

A confirmed case requires laboratory definitive evidence only.

Laboratory definitive evidence

1. Isolation of variola virus, confirmed at the Victorian Infectious Diseases Reference Laboratory;


2. Detection of variola virus by nucleic acid testing, confirmed at Victorian Infectious Diseases Reference Laboratory.

Probable case

A probable case requires either:

1. Clinical evidence and laboratory suggestive evidence;


2. Clinical evidence and epidemiological evidence.

Laboratory suggestive evidence

1. Detection of a poxvirus resembling variola virus by electron microscopy;


2. Isolation of variola virus at a non-reference laboratory[1];


3. Detection of variola virus by nucleic acid testing at a non-reference laboratory[1]

Clinical evidence

A clinical syndrome consistent with smallpox[2] as judged by a specialist physician[3].

Epidemiological evidence

1. Within 7 to 19 days prior to illness onset the case has:

a. An epidemiological link to a confirmed case;


b. An epidemiological link to a case in a chain of epidemiologically linked cases where at least one case is confirmed;


c. An identified mechanism of exposure to variola virus.

  1. In the absence of meeting criterion 1 of the laboratory suggestive evidence, if confirmatory testing at a reference laboratory subsequently confirms the specimen as not being variola virus, this criterion would not be considered to have been met as the laboratory suggestive evidence component of the case definition.
  2. Refer to the current Smallpox SoNG for clinical evidence (
  3. Such as an infectious diseases physician, clinical microbiologist or public health physician.

Archived version/s for reference:

2004 - Version 1.0 - ARCHIVED - Smallpox case definition - PDF 276 KB

2004 - Version 1.0 - ARCHIVED - Smallpox case definition - Word 25 KB

In this section