Legionnaires' Disease Outbreak in Sydney: 1 Dead, 12 Infected - What You Need to Know

There are now 12 confirmed cases of Legionnaires' disease in people who spent time in central Sydney between March 13 and April 5, up from the six cases that had been diagnosed as of April 10, the department said. One of the confirmed cases has died in the hospital, and 11 have required hospitalisation.

NSW Health on Thursday urged anyone who spent time in central Sydney and surrounding areas in late March or early April to be aware of symptoms of Legionnaires' disease, including fever, chills, a cough, and shortness of breath.

"Outbreaks sometimes occur when bacteria from environmental sources such as cooling towers atop large buildings become contaminated," said Vicky Sheppeard, Director of the Southeast Sydney Local Public Health Unit.

"NSW Health continues to work closely with the City of Sydney to identify, inspect and sample any cooling towers in the CBD potentially implicated in the outbreak. To date, over 165 cooling towers have been inspected and tested," she added.

According to the World Health Organization, the Legionnaires' disease mortality rate can be as high as 80% in untreated immunosuppressed patients.

What is Legionnaires' disease?

Legionnaires' disease is a serious form of pneumonia caused by infection with Legionella bacteria, which are found naturally in freshwater. According to the U.S. Centres for Disease Control and Prevention (CDC), Legionella most commonly causes either Legionnaires’ disease or Pontiac fever — a milder respiratory illness.

Rarely, the bacteria can also cause infections in wounds or other parts of the body, including the heart. The condition was first identified after an outbreak in 1976 at a Philadelphia convention of the American Legion, which gave the disease its name.

Symptoms of Legionnaires' disease

According to the U.S. CDC, symptoms of Legionnaires' disease typically begin 2 to 14 days after exposure, but may take longer to appear. They are similar to those of other pneumonias and include:

• Cough
• Fever
• Headache
• Muscle aches
• Shortness of breath

Other symptoms like confusion, diarrhoea, or nausea may also occur.

Risk Factors of Legionnaires' disease

While most healthy people exposed to Legionella don’t get sick, certain individuals are more vulnerable. The U.S. CDC identifies risk factors such as age above 50, smoking, chronic lung disease, and a weakened immune system that can increase the likelihood of developing Legionnaires’ disease.

Causes and Spread of Legionnaires' disease

The U.S. CDC explains that Legionella bacteria spread primarily through inhalation of contaminated mist or water droplets — commonly from cooling towers, hot tubs, fountains, or large plumbing systems. Infection from drinking water or person-to-person transmission is rare.

Legionella can also grow in unusual places — like the windshield wiper fluid tank of a vehicle. The CDC advises using genuine windshield cleaning fluid and following manufacturer recommendations to prevent bacterial growth.

Testing and Diagnosis of Legionnaires' disease

A chest X-ray can confirm pneumonia, but further testing is required to identify Legionella. The U.S. CDC notes that diagnostic tools include a urine antigen test or laboratory testing of sputum or lung washing samples to confirm the bacteria as the cause of pneumonia.

Prevention of Legionnaires' disease

Prevention involves reducing the risk of Legionella growth in water systems, the U.S. CDC recommends. This includes implementing water management programs for large buildings, maintaining hot tubs and fountains, and avoiding the use of plain water in vehicle windshield tanks.

At home, the CDC suggests keeping water heaters at appropriate temperatures and cleaning shower heads to help reduce risk.