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ResourcesPage content: Legionella Link Newsletter | DHS Supporting Legionella Research | Department of Human Services sampling of the water circulating in cooling tower systems | Fact Sheets | Legionella Program Articles | Trade journal articles | History of the Legionella Program & Legislative Reform | Legislative Reform - Managing the health risk associated with cooling towers | Links to related sites Legionella Link
DHS Supporting Legionella ResearchElevated water temperatures and nutrients from organic matter create an ideal environment for multiplication of micro-organisms inside cooling towers. Micro-organisms commonly found in cooling towers include, bacteria, algae, fungi, protozoa and viruses. Protozoa feed on bacteria through phagocytosis however some bacteria are not digested after internalization and are able to survive and multiply inside the protozoa whilst being protected from their environment. Legionella bacteria have been shown to have this ability to survive and replicate and when released from protozoa have been reported to have increased resistance to biocides and high temperatures. Understanding the effect biocides, chemical additives and temperature have on Legionella and protozoa is important for developing management strategies for cooling tower systems and protecting public health. Department of Human Services is supporting research which looks at the effectiveness of biocides in the control of protozoa in cooling towers. The two key players in this research are CSIRO Materials Science and Engineering and Flinders University, Environmental Health. The research objectives are to determine if the biocides commonly used in cooling towers are effective disinfectants to environmental isolates of protozoa; to assess whether cooling tower chemical additives enhance or inhibit biocide activity towards protozoa; and to determine if temperature plays an important role in biocide efficacy and proliferation of protozoa.
Department of Human Services sampling of the water circulating in cooling tower systemsThe Department’s Legionella Program incorporates targeted sampling of the water in cooling tower systems (CTS). Sampling may occur:
Samples are tested for the presence of Legionella and for Heterotrophic Colony Count. Results are now available for water samples taken by the Legionella Program during the period 1 January 2000 to 30 September 2008 (Graphs and figures shown below). It should be noted that the number of samples taken varies considerably from month to month. The initial 12 months of the program (starting from March 2001) saw an intensive sampling program with approximately 1500 samples being taken over the year. With the Department’s focus now on Risk Management Plans, auditing and renewal of registration, the numbers of CTS samples taken have decreased. The seasonal fluctuations are clearly shown in the positive Legionella results. It can be seen that in the warmer months, the number of Legionella positives are greater. It is important that in the warmer months maintenance and treatment of CTSs are greater to ensure compliance with the Health (Legionella) Regulations 2001, and minimise the risk to public health. Many businesses shut down for extended periods over the Christmas – New Year season, and start up processes should be implemented according to DHS guidelines. Since the introduction of the Health (Legionella) Regulations 2001, there has been a decrease in the numbers of cases being notified to the Department, specifically for Legionella pneumophila serogroup 1. This is the type of Legionellosis most commonly associated with outbreaks. The number of outbreaks has also decreased. Details for latest case statistics can be found on the table below titled "Notifications of Legionella pneumophila in Victoria 2000 – 21 October 2008". For daily reports of Legionellosis notifications including other Legionella species, use the following link: Daily reports of Legionellosis notifications including other Legionella species Documents for download
Fact SheetsEvaporative Coolers: An Operation and Maintenance Guide for Owners
Legionella Program Articles
Trade journal articlesHistory of the Legionella Program & Legislative ReformDuring late 2000 and early 2001 the Victorian Government strengthened the regulatory framework to improve the testing and maintenance standards for cooling towers, and to reduce the impact on the community of Legionnaires' Disease. In summary the key aspects of the strategy were to:
The strategy has been implemented by the Department of Human Services, Building Commission and the Plumbing Industry Commission. Legislative Reform - Managing the health risk associated with cooling towers Government response The Government's major commitment to improving the management and control of Legionnaires' disease is consistent with this policy. Whilst Legionella, the causative organism of Legionnaires' disease, is most commonly associated with cooling towers, there have been instances when it has been transmitted by other warm water systems, such as spas. In 1979, Legionnaires' disease was proclaimed as a notifiable infectious disease in Victoria, requiring all cases to be notified to the then Health Department Victoria. This requirement was continued under the Health (Infectious Diseases) Regulations 1990, which incorporates the Guidelines for the Control of Legionnaires' Disease (1989) referred to as the ‘Guidelines'. The Guidelines were written in a style which is not prescriptive and which was originally intended to provide guidance only. Registration of cooling towers is not required under the current Regulations and there is no requirement for audit and inspection of these systems. Findings & recommendations of the DHS working partyAlthough Legionnaires' disease has been relatively rare, notifications under the Health (Infectious Diseases) Regulations 1990 have risen significantly in recent years. Epidemic investigations implicate cooling towers and associated pipe systems, a proportion of which have been shown to not meet current best practice, and/or to be contaminated with the causative organism, Legionella pneumophila bacteria. Investigations indicate that improvements in maintenance are required, and that the minimum approach has often been shown to be inadequate. The existing incidence and potential impact of Legionnaires' disease justify a review of the arrangements in place, including those of regulation and interagency cooperation, for the enforcement of best practice for maintenance of cooling towers. For these reasons, the Legionella Working Party was established in December 1999 to advise the Minister on options for managing health risk associated with cooling towers. The Legionella Working Party considered a range of feasible options for enforcement of best practice for maintenance of cooling towers, including the roles and responsibilities of agencies and associated costs and benefits associated with the feasible options. Regulatory impact statement, health (legionella) regulations 2001The proposed Health (Legionella) Regulations 2001 form part of a larger package of measures being implemented by the Victorian Government to reduce the risks of contracting Legionnaires’ disease associated with the operation of cooling tower systems and warm water systems. The package of controls is based on the recommendations of the Legionella Working Party and on consultation undertaken with stakeholders during 1999-2000. Links to related sitesApproaches to Legionella Control in Other States of Australia
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Last updated:
30 December, 2009
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