The Department of Health & Human Services is advising the community to be alert for Legionnaires' disease, with the illness more common at this time of year.
Samples were taken from several cooling towers in Cranbourne today, following the detection of four cases linked to an area neighboring the Cranbourne shopping centre.
The towers, in the vicinity of the shopping centre, were then disinfected. There are no towers at the centre.
Victoria's Chief Health Officer, Professor Charles Guest, said the four cases had occurred since February.
Professor Guest said the illness is more prevalent at the change of seasons, when towers are either activated or deactivated.
"People who may be suffering from pneumonia or flu-like symptoms should visit their GP, who will assess and advise on the need for testing for Legionnaires' disease," he said.
Legionnaires' disease causes flu-like symptoms such as headache, fever, chills, muscle aches and pains, followed by respiratory problems and pneumonia developing over three or four days. The onset can be up to 10 days after the initial contact with the bacteria. Higher risk groups are people aged over 50, heavy smokers, heavy drinkers, people with diabetes or chronic lung disease and those with lowered immunity.
Legionnaires' disease infection is acquired through breathing in very fine droplets of water which contain the bacteria, such as spray drifts which are vented off from a contaminated cooling tower. Thorough management, decontamination and cleaning of towers is highly successful in eliminating risk.
The Legionella bacteria occurs naturally in the environment, mainly in water and soil. It is normally in very low concentrations but can increase markedly, particularly in man-made aquatic environments with warm recirculating water, such as air conditioning cooling towers.
Professor Guest said it could be up to 10 days before the results from the Cranbourne tower sampling were determined. People who have been exposed to the potential source could still develop symptoms over the next 10 days.
The four people affected, aged 45 to 78, required hospital treatment. Three have since been discharged.
So far this year 47 people have contracted Legionnaires' disease, with 28 notifications for the same period last year. In Victoria each year there are between 70 to 80 cases of Legionnaires' disease.
Reviewed 12 May 2017