There has been a second outbreak of legionnaires disease in Sydney with a further three people hospitalised.
Two men, aged 64 and 76 and a woman, 85, are currently being treated for the bacterial lung infection at St George Hospital.
NSW Health and Kogarah Council investigators suspect a cooling tower in or near the St George Hospital may be responsible for the latest outbreak.
NSW Health confirmed that authorities began examining cooling towers in Sydney's south in late March.
A cooling tower that was tested on March 22 returned a positive result for legionella, but officials only received the results last week.
The tower was cleaned and decontaminated on March 29. The results of further testing will be available in the next couple of days.
The latest outbreak in Sydney's south follows the death of a man in his 80's last month who contracted the disease in Sydney's CBD.
In early march nine people were infected as a result of an outbreak near Town Hall station. It led to NSW Health and City of Sydney inspectors testing 1,400 cooling towers registered with the City of Sydney.
The source of both outbreaks has still not been identified.