Victorians over 50, heavy smokers, drinkers and those suffering chronic diabetes, lung and immune illnesses have been told to be on alert after a number of legionnaires' disease cases in central Melbourne.
Three men, aged between 52 and 72, reported visiting the CBD's southeast before they contracted the potentially fatal bacterial infection in early to mid-February, the Department of Health and Human Services said.
The airborne disease possibly spread via a contaminated air-conditioning system between Queen and Spring streets, prompting the regulator to start scouring about 100 cooling towers on Friday.
"It'll take through the weekend and into early next week to make sure we can sample and disinfect all of the ones that we're most concerned about," deputy chief health officer Dr Brett Sutton told reporters on Friday.
Until the source is found, Melburnians should go about their business but contact their doctor if flu-like symptoms give way to pneumonia, Dr Sutton said.
"It's a rare disease and, for most people, they won't develop symptoms of legionnaires' disease," he said.
"(But) it is potentially fatal. That's why we've got a stringent process for overseeing cooling towers."
