Disease Toll Rises To 18
The Age
Tuesday November 3, 1998
Three more suspected cases of legionnaires' disease have been uncovered after publicity about Victoria's worst outbreak of the potentially fatal disease. There are now eight suspected cases along with the 10 confirmed.
The two most seriously ill patients remain in intensive care at the Northern Hospital. Another two have been discharged and the others are all improving.
The state's chief health officer, Dr Graham Rouch, said yesterday further cases could turn up but he was reasonably confident the outbreak was under control.
Health officers have tested all the cooling towers in the industrial estate north of Mahoneys Road, Thomastown, believed to be the source of the infection, but were yesterday widening their testing to the industrial areas east and west of the original site as a precaution. It will take several more weeks before the source of the outbreak is confirmed because of the testing and re-testing involved.
Owners or managers of cooling towers must completely clean and disinfect them every three to six months, do monthly inspections and testing under state regulations, and keep records.
Dr Rouch was confident self-regulation was working.
If a tower is implicated as the source of infection, the owner could be fined as well as face prosecution under occupational health and safety legislation and civil claims for damages from individuals if they have not complied with the regulations.
LEGIONNAIRE'S DISEASE
What it is: a lung infection caused by Legionella bacteria. Are more than 20 species of legionella but legionella pneumophila causes the majority of cases.
Where it occurs: The bacterium occurs naturally but usually in low levels in water and soil and can be found in rivers, creeks, hot springs and other bodies of water and soils. It can multiply rapidly however in systems which have warm, recirculating water such as the cooling towers of commerical airconditioners, spa pools or shower heads if the water is kept below 60 deg celcius.
Catching the disease: It can be acquired by inhaling aerosols (very fine droplets of water) which contain the bacterium. The normal operation of cooling towers produces aerosols which are dispersed outside through its air exhaust. Depending on wind conditions, the aerosols can travel about 200metres from the tower. The further it travels, the more the bacterium is diluted by the air. It is rare for these aerosols to be dispersed inside the building unless the system's intake is close to its air exhaust (equivalent to having a car airconditioner's intake next to the exhaust pipe).
It is not contagious (ie spread from person to person) and the risk of the bacterium causing disease depends on how virulent it is and the individual's immunity. Older people, smokers, those with respiratory illness and those who are immunocompromised are at higher risk.
Legionnaires' disease can not be contracted from domestic airconditioners because they do not use warm, recirculating water. In rare cases, the bacterium could multiply in an evaporative aircooler which used warm rather than cold water.
© 1998 The Age