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Legionella, legionellosis and Legionnaires' disease

Legionella are a class of bacteria found in the natural environment around the world. There are over 50 species of Legionella bacteria, some of which can cause disease in humans. The most common disease causing species are Legionella pneumophila and Legionella longbeachae.

Most Legionella species, including Legionella pneumophila, thrive in warm water, and need the presence of other organisms (e.g. amoebae) to multiply. They grow readily in man-made environments such as inside plumbing fixtures and pipes, where warm temperatures and the build-up of nutrients and microorganisms on surfaces (called biofilm) provide an ideal environment.

Legionella longbeachae is found in soils, compost and potting mixes.

Legionellosis is a collective term for diseases caused by Legionella bacteria including the most serious, Legionnaires’ disease, as well as the less serious condition of Pontiac fever.

Legionnaires’ disease is a type of pneumonia caused by the Legionella bacteria. Humans might contract this disease by inhaling microscopic/invisible droplets (aerosols) of contaminated water from man-made systems such as hot or warm water systems, showerheads, spa baths and fountains.

While most people are unlikely to get Legionnaires’ disease, some groups are more at risk than others.

Read more about Legionella and Legionellosis

Prevention and risk management

Information for clinicians

The following tools and resources provide more information to help clinicians with Legionella infection control.

Communicable disease control guidance - Find links to key guidelines and protocols, notification forms and process information.

Water contamination and endoscopic reprocessing – Module 6.5 (water quality)
Six training modules designed to provide healthcare professionals with education and training tools to minimise adverse patient outcomes associated with breaches in the reprocessing of flexible endoscopes and accessories. Module 6 relates to quality assurance and section 6.5 is about water quality.

It is recognised that hospital tap water may be contaminated with a variety of microorganisms. Pseudomonas and related species, atypical mycobacteria and Legionella are the most important.

Therapeutic Guidelines - read about antibiotic therapy for Legionnaires’ disease . Queensland Health staff can refer to the Therapeutic Guidelines available through CKN.

Patient management response guideline (PDF 98kB)- guidelines to assist in the patient management response if Legionella is detected in a facility's water supply.

Reducing risks around the home

Read about simple household precautions that can be taken to reduce the risk of infection by Legionella (particularly for vulnerable people) including correct installation and maintenance of hot water systems, plumbing fixtures and pools and spas.

Information for industry

Read workplace or industry guidelines and requirements which include references to reducing risks associated with Legionella.

2013 Legionella pneumophila outbreak investigation

A review by the Chief Health Officer of the prevention and control of Legionella pneumophila infection in Queensland was initiated at the request of Health Minister, the Honourable Lawrence Springborg, on 6 June 2013.

The purpose of the review was to:

  • investigate the circumstances surrounding the notification of and response to Legionnaires' disease in two patients, and the subsequent death of one patient, at The Wesley Hospital in Queensland in late May and early June 2013
  • make recommendations regarding the future management of Legionella pneumophila in Queensland.

Read the Chief Health Officer's findings, conclusions and recommendations (PDF 379kB).

2013 test results

On 7 June 2013, Queensland's 17 Hospital and Health Services were directed, and 103 private and day hospitals and health facilities were requested, to test their potable water systems for Legionella.

View the test results (XLS 87kB) which informed the Chief health officer’s review.

Last updated: 6 November 2014