Legionnaires' disease has been detected in Sydney -- here's what you need to know

Early symptoms are similar to that of a cold or flu. Photo: Shutterstock. Four men have been hospitalised in Sydney after being diagnosed with Legionnaires' disease.

The men are believed to have contracted the illness from an air conditioning system in Sydney's Town Hall.

Legionnaires’ disease is a type of pneumonia caused by a bacterial infection of the lungs.

It usually develops after a person breathes contaminated water vapour or dust containing Legionella bacteria, germs that thrive in warm water of the sort found in cooling towers, hot water tanks, spa baths and plumbing systems.

The spread of the bacteria is also thought to be transmitted from hand to mouth.

It's important to know that Legionella is not spread from person to person.

The time from exposure to the onset of symptoms is typically between two and 10 days.

Those most susceptible to contracting the disease include people aged 50 years and over, regular smokers and the immunosuppressed. It's extremely rare in children.

The symptoms

The first symptoms of Legionnaires’ disease are non-specific flu-like symptoms including fever, headache and muscle aches. There may also be a mild cough with or without phlegm. Some people may develop diarrhoea, vomiting and abdominal pain.

Illness usually progresses rapidly and the chest infection (pneumonia) symptoms become obvious, with high fever, shortness of breath and chest pain being typical symptoms.

The disease is also associated with a less serious condition of Pontiac fever, which only lasts a couple of days and people generally without treatment.

Legionella bacteria is usually spread by manufactured water systems. Photo: Shutterstock.

There are over 50 different species of Legionella bacteria. In Australia the most common species that are known to cause human disease are Legionella pneumophila and Legionella longbeachae.

In Australia, legionella infections are believed to account for 5–15 per cent of community-acquired pneumonia.

It is difficult to distinguish a Legionella infection from other types of pneumonia by symptoms alone and other medical tests are required to diagnose the disease. Such tests include sputum, blood and/or urine tests, which may need to be repeated to confirm the diagnosis.

An infected person usually needs to be admitted to hospital for appropriate antibiotic treatment and care. Because the progress of the infection can be rapid, it is important that antibiotics be given promptly once the diagnosis is suspected.

People who receive early effective treatment usually begin to improve within three to five days.

Without early treatment, the illness can progress to severe illness, kidney failure and death.

Legionnaires' in Australia

From 2003 to 2012, there were an average of 324 legionellosis notifications per year to State and Territory governments in Australia.

The most recent outbreak in Australia was in Melbourne in April, 2000.

It resulted in 125 confirmed cases, with 95 people hospitalised. Four people died from the outbreak.

The investigation traced the source of the infection to the cooling tower at the Melbourne Aquarium. All except one person had been at or near the Aquarium between the dates of April 11 and 21. One case had visited the Aquarium on 25 April.

The outbreak is the worst on record since ten people died in Wollongong in 1987 from the disease.

Since the Melbourne incident, legionella infection statistics are required to be reported by the state governments as a notifiable disease.

Town Hall in Sydney, the suspected source of the most recent outbreak. Photo: Shutterstock.

Currently, NSW Health and the City of Sydney have launched an investigation into the outbreak in Sydney.

They are checking cooling towers, starting in the Town Hall area, because outbreaks can be linked to air conditioning systems in large buildings.

The health department is urging anyone who has visited the Town Hall area and has symptoms such as fever, chills, a cough and shortness of breath to see their doctor.

For further information please see contact your local Public Health Unit on 1300 066 055 or visit the NSW Health website.

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