Health authorities are investigating whether earlier cases of Legionnaires’ disease are linked to an outbreak in Sydney’s CBD.
Four people contracted legionnaires disease after spending time in the Druitt, Market, Sussex and Pitt Street areas, NSW Health reported on Wednesday.
Legionnaires’ disease explained
Expert in environmental microbiology Dr Harriet Whiley explains the symptoms and causes of legionnaires’ disease after an outbreak in Sydney.
Investigators suspected that an infected cooling tower near Town Hall Station was responsible for an outbreak.
Three men aged in their sixties and one in his 30s are receiving treatment for Legionnaires’ disease in hospital. Three of the patients work in the area and one was visiting.
The bacterial lung infection causes fever, chills, a cough and shortness of breath, and can be fatal.
On Thursday NSW Health said no new cases of the pneumonia-type infection had been detected, but health authorities were revisiting patients who had contracted the disease, including one person identified in February.
“As part of its investigation, NSW Health has been re-interviewing other cases of Legionnaires’ disease notified in recent months,” NSW Health said in a statement.
“A case identified in early February, who has now recovered, has reported visiting several locations in the CBD,” the statement read.
“This may be unrelated to the current outbreak and investigations are continuing”
Legionnaires’ occurs after a person breathes in contaminated water or dust, and outbreaks have been associated with the air-conditioning units used in large buildings.
Legionella bacteria get into the water supply that cools the system and multiply.
Passers-by can contract the disease from contaminated vapour drifting in the wind outside.
Those most at risk include middle-aged and older people, heavy smokers and those with chronic lung disease.
Legionnaires cannot be transmitted person-to-person.
NSW Health’s director of communicable diseases, Vicky Sheppeard, said people who developed the disease were diagnosed by X-ray or a urine test and usually required antibiotic treatment in hospital.
“The time from exposure to the onset of symptoms is typically between two and 10 days, so people who were exposed could have symptoms already or develop them over the next week,” Dr Sheppeard said on Wednesday.
Anybody who lived, visited or worked near Town Hall and developed those symptoms should visit their doctor.
NSW Health and City of Sydney inspectors are investigating cooling towers in the CBD, starting in the Town Hall area.
The City of Sydney council maintains a register of water cooler systems and can order that they be maintained or shut down if sampling finds evidence of Legionnella.
Business owners are expected to have the units inspected every month, cleaned every six months and certified annually.
The council released a statement on Wednesday evening confirming that inspections of the 1400 cooling systems on its register were up to date.
“The City is assisting NSW Health with the investigation and sampling of a number of cooling towers in the city centre,” the statement said.
“The City is also providing facilities and resources to enable the operation to be carried out as quickly as possible.
“Any samples will be sent for analysis to a state government-owned laboratory.”
Hospitals are required to confidentially notify public health officials of cases of Legionnaires disease in NSW.
Public health unit staff interview patients or their carers about their illness and possible exposures.
If two case are linked, staff investigate possible sources of infection, which are then assessed and cleaned if necessary.
Outbreaks of the disease have previously occurred in Sydney in 2011, 1995, 1994, 1993, 1992 and 1989.