Legionellosis case definition

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

Page last updated: 20 December 2012

(Effective 1 January 2013)

Reporting

Both confirmed cases and probable cases should be notified.

Confirmed case

A confirmed case requires laboratory definitive evidence AND clinical evidence.

Laboratory definitive evidence

Isolation of Legionella

OR

Detection of Legionella urinary antigen

OR

Seroconversion or a significant increase in antibody level or a fourfold or greater rise in titre to Legionella.

Clinical evidence for confirmed cases

Fever

OR

Cough

OR

Pneumonia

Probable case

A probable case requires laboratory suggestive evidence AND clinical evidence.

Laboratory suggestive evidence

Single high antibody titre to Legionella

OR

Detection of Legionella by nucleic acid testing

OR

Detection of Legionella by direct fluorescence assay.

Clinical evidence for probable cases

Fever AND Cough

OR

Pneumonia


Legionellosis changes

Confirmed case

Under Laboratory definitive evidence, Point 12, 'Presence of Legionella urinary antigen' has changed to 'Detection of Legionella urinary antigen'.


Probable case

Under Clinical evidence for probable cases, ‘Fever OR Cough OR Pneumonia’ has changed to ‘Fever AND Cough OR Pneumonia.’

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