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Building owners throughout downtown Auckland are being urged to test and disinfect air-conditioning systems after high counts of potentially lethal bacteria were found in cooling towers on two neighbouring office blocks.
Both rooftop towers have been disinfected against legionella, and one of them given a clean bill of health, but a communication glitch over Christmas involving the second building means more time is needed before it can be re-tested.
Medical officials say that although there is only a small risk to people's health, everyone who works, lives or visits the central business district should be alert for possible symptoms of legionellosis.
Neither can the Auckland Regional Public Health Service rule out the possibility of cross-contamination between the two buildings and neighbouring properties in an area of central Auckland it was not prepared last night to identify.
The severity of the condition can range from a mild self-correcting respiratory illness called pontiac fever to full-blown legionnaires' disease, a form of pneumonia blamed for three deaths in Christchurch in 2005 and one in the Manukau City coastal suburb of Beachlands last year.
Attention focused after the Christchurch deaths on a cooling tower in a fertiliser plant as a possible source of bacteria which infected 19 people, and the Beachlands case prompted the public health service to call on residents to clean rainwater tanks.
Two police officers received compensation payouts in 2002 after contracting legionnaires' disease from their Counties Manukau headquarters in Otahuhu, which was evacuated the next year while its air-conditioning cooling tower was replaced.
Auckland medical officer of health Cathy Pikholz said last night that people should not be deterred from going about their normal business in downtown Auckland, but should visit their GPs if they developed symptoms suggesting legionellosis.
These included aching muscles, headaches, tiredness, loss of appetite and coughing, followed by high fever, chills and occasional diarrhoea.
People usually catch the infection by inhaling mists or spray from water containing legionella bacteria, rather than by contact with others or drinking contaminated liquids.
About 50 cases of legionellosis are reported to New Zealand health authorities annually, of which 4 per cent to 5 per cent prove fatal.
Those most at risk are elderly people and heavy smokers.
Dr Pikholz said "appropriate corrective action" had been taken at both affected cooling towers, the first of which was reported on December 17 as having excessive legionella bacteria, but had since been given a clean bill of health.
The second tower was reported to her organisation in an email on Christmas Eve. But the would-be recipient had left work for Christmas, so it was discovered only on Thursday, when immediate action was taken to disinfect the cooling tower and notify the Department of Labour.
Auckland City Council acting chief executive John Duthie said the high bacteria counts were reported from routine monthly testing of cooling towers by building owners, so the discovery was evidence of a system which was working.
He would not disclose the locations of the office blocks, but said they were "across the road from each other".
Mr Duthie said the council had enlisted the help of the Property Council in urging all building owners to take the precautionary step of testing for legionella ahead of a required monthly cycle, and to treat their cooling towers with extra chlorine.
"There are no reports of anyone having fallen ill with the diseases caused by legionella bacteria but we ask that this testing be done before the next due date."
Dr Pikholz would not speculate on the potential for cross-contamination of downtown Auckland buildings or how far the bacteria could spread in aerosol form, whether through air-conditioning intake systems or through the general atmosphere.
But she said: "Obviously our level of concern went up when we got [notice of] the second one.
"We think the risk is low, but if people suspect they may have symptoms of legionellosis they should go to their doctor."
Property Council chief executive Connal Townsend said his organisation was sending out emails last night to all its central Auckland members to alert them to the legionella discovery.
