Health alert
- Status:
- Resolved
- Alert number:
- 240729
- Date issued:
- 19 Aug 2024 - Update to alert issued 29 July 2024
- Issued by:
- Dr Clare Looker, Chief Health Officer
- Issued to:
- Health professionals and the Victorian community
Key messages
- The Department of Health managed an outbreak of Legionnaires’ disease (legionellosis) with cases notified across metropolitan Melbourne and surrounding areas. While some public health actions are still underway, this outbreak is under control with the source having been identified and public health risk removed.
- Between 26 July and 20 August there were 114 confirmed cases, mostly in adults aged over 40 years. Most cases required hospitalisation, with a number of admissions to intensive care. All cases visited or resided in metropolitan Melbourne.
- Legionnaires’ disease can cause a chest infection with symptoms of fever, chills, cough, headache and muscle aches and pains. Other atypical symptoms may include nausea, vomiting, diarrhoea and confusion.
- While the public health risk from the source of this outbreak has been removed, the bacteria that causes Legionnaires’ disease is commonly found in the environment and there is a low risk of infection from day-to-day life. The risk of Legionnaires’ disease can be decreased through various prevention measures.
- Operators of cooling towers are advised to ensure compliance with their cooling tower testing, servicing and auditing requirements.
What was the issue?
The Department of Health identified an outbreak of Legionnaires' disease (also known as legionellosis) with significant increase in the numbers of cases across multiple locations in metropolitan Melbourne between 26 July and 20 August 2024.
The cooling tower identified as the source of this outbreak has been found. This tower was tested on 30 July 2024 and disinfected within 24 hours of that visit. We are confident the source has been controlled with risk to the community now removed.
Test results indicate that the outbreak is caused by Legionella pneumophila serogroup 1, which can be detected through a Legionella urinary antigen test. This strain of Legionella is predominantly found in water systems and not in potting mixes.
Legionnaires’ disease is caused by Legionella bacteria which are widespread in the environment. Legionella is found in natural bodies of water such as rivers, lakes, creeks and hot springs. It is also found in spas, warm water systems and artificial systems that use water for cooling, heating or industrial processes such as cooling towers, as well as potting mix.
Recommendations
Please refer to the Legionellosis (Legionnaires’ disease) page and the Better Health websites for prevention strategies and more information about Legionnaires’ disease. Of note, operators of cooling towers are advised to ensure compliance with their cooling tower testing, servicing and auditing requirements.
Reviewed 20 August 2024