Three men have been diagnosed with legionnaires' disease in Sydney's northwest, sending the health department searching for a contamination source in the area.
All three patients developed the type of legionnaires' disease that develops after a person breathes in contaminated water droplets, NSW Health said in a statement on Tuesday.
The Hills Shire Council and public health units in the area have started precautionary inspections of cooling towers, as outbreaks can be associated with contaminated air conditioning systems.
The bacterial infection can not be spread from person to person.
"The bacteria that cause legionnaires' disease live in water and can multiply in the water used to cool air conditioning systems, so infection is prevented by routinely maintaining and treating these systems," NSW Health's communicable diseases director Dr Vicky Sheppeard said in a statement on Tuesday.
"People outside can be exposed to the bacteria when a water cooling system emits contaminated water particles into the air."
The disease causes fever, chills, a cough and shortness of breath.
The three men each spent time in the Castle Hill area when they contracted the infection and reported becoming unwell between February 3 and 5.
NSW opposition spokesman Walt Secord said the government needed to be vigilant and called for a comprehensive surveillance plan of air cooling tower systems.
"With the warm winters and extremely hot summers, the state government needs to be vigilant in monitoring air cooling towers and alerting the community," Mr Secord said in a statement.
"Legionnaires' disease can be deadly for the elderly - and those with compromised immune systems."
