NSW Health said there were now 12 confirmed cases of the disease, all in people who spent time in the Sydney CBD between March 13 and April 5.
Health officials gave their condolences for one of the patients, who had died in hospital last week.
Legionella bacteria have been found in a cooling tower in the CBD, and further testing is being conducted to see if it is the source of the disease outbreak
The tower is now being decontaminated.
People who were in the Sydney CBD between March 13 and April 5 have been advised to be aware of symptoms of Legionnaires’ disease, which include fever, chills, coughing, and shortness of breath.
Symptoms can appear up to 10 days after exposure to the bacteria, which is not spread from person to person.
Twelve people were infected, with 11 hospitalised and one person treated out of hospital.
“Legionnaires’ disease is caused by infection with Legionella bacteria,” NSW Health’s Doctor Vicky Sheppeard said.
“Outbreaks sometimes occur when bacteria from environmental sources such as cooling towers atop large buildings become contaminated.
“It is not spread from person to person.
“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.
“Most building owners have responded quickly to ensure that their cooling towers are operated and maintained in compliance with the NSW Public Health Regulation 2022.”
Anyone feeling unwell should seek medical advice from the GP or the emergency department.