Melbourne Legionnaires’ disease outbreak tops 100 cases
In a follow-up on the Legionnaires’ disease outbreak affecting metropolitan Melbourne and surrounding areas, Chief Health Officer for the Victoria Department of Health, Dr Clare Looker says there have been 107 confirmed and 5 suspected cases notified since Friday 26 July, mostly in adults aged over 40 years.
All cases have visited or reside in metropolitan Melbourne. Those most at risk are adults aged over 40 years, especially people with other medical conditions or immune compromise, or who smoke.
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. While officials are confident the source has been controlled, there may be some individuals who are yet to develop symptoms or who are already symptomatic but are yet to seek testing.
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.
Legionnaires’ disease usually presents as a chest infection with symptoms such as fever, chills, cough, headache and muscle aches and pains. Other atypical symptoms may include confusion, nausea, vomiting and diarrhea. Some people with Legionnaires’ disease may also develop kidney impairment. Legionnaires’ disease can lead to serious illness and cases may require hospitalization.
Legionnaires' disease is spread by breathing in fine droplets of water that contain Legionella bacteria. It is not commonly spread from person-to-person or by drinking contaminated water.