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Seven people from Potts Point, an affluent inner-city suburb less than two km from the Sydney Harbour Bridge and Sydney Opera House, have contracted Legionnaires' disease since May, Xinhua News Agency reported.

The cases include a man aged in his 80s who became ill in late June and has since died.

The remaining six people were hospitalized for treatment. Five have been discharged and the sixth is recovering.

None of the patients, all of whom were aged between 45 and 95, were known to each other but may have been exposed to a common source of infection in the area, the SESLHD said.

Legionnaires' disease is caused by infection with the Legionella bacteria. It cannot spread between people but a person can become infected by inhaling water particles from a contaminated source.

The SESLHD in June advised anyone who had been in Potts Point to be vigilant for symptoms, including fever, chills, shortness of breath and a cough.

The district's public health unit director, Vicky Sheppeard, said on Thursday that health authorities and the City of Sydney are investigating and testing all potential contaminated water sources in the areas visited by the seven patients.

"The district has requested building owners disinfect their cooling towers on two occasions since the investigation began in June," she said in a statement.

Legionnaires' disease is a type of serious pneumonia caused by a type of bacteria called Legionella, according to the US Centers for Disease Control and Prevention (CDC).

The symptoms of Legionnaires' disease usually develop two to 14 days after exposure to Legionella bacteria, however, it can take longer. The symptoms of Legionnaires' disease are similar to other types of pneumonia. Symptoms include cough, fever, muscle aches, headaches and shortness of breath. Other symptoms like confusion, diarrhea, or nausea can also occur.

- IANS