The six folks, together with two ladies and 4 males aged between their 40s to 70s, visited areas on Elizabeth Avenue, Clarence Avenue, Park Avenue and Martin Place 10 days earlier than turning into symptomatic.
"All six folks have been admitted to hospital for remedy of their pneumonia, with one individual now discharged," NSW Well being stated.
No single supply for the circumstances has been discovered but however testing on cooling towers throughout the town is underway.
"NSW Well being environmental well being officers have labored with the Metropolis of Sydney to examine and pattern 124 excessive precedence cooling towers within the space," NSW Well being stated in an announcement.
Well being authorities have directed the house owners of six towers to repair defects.
These towers have undergone assessments to find out if they're the potential supply of the infections.
NSW Well being says signs of Legionnaires' illness, which incorporates fever, chills, a cough and shortness of breath, can develop as much as 10 days from the time of publicity.
It will possibly result in extreme chest infections corresponding to pneumonia and often requires antibiotic remedy in hospital.
The micro organism that causes Legionnaires' illness is usually related to contaminated cooling towers of enormous buildings.
Individuals might be uncovered to the micro organism if contaminated water particles are launched into the air by way of cooling methods after which breathed in.
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