COMMUNICATIONS

Media Release - 26/08/2005

Update on Legionnaires Disease

The spatial relationship of Legionnaires Disease cases in Christchurch suspected from the case control study carried out by the Canterbury District Health Board last weekend has now been supported by the second arm of the scientific study.

Medical Officer of Health Dr Alistair Humphrey said that the spatial relationship of the cases have been defined in five different ways and each time these have centred on the south west of the city.

“There are 35 cooling towers located within the most significant clusters but until we receive microbiological results from all of them we cannot exclude the fact that there may be more than one potential source.”

“Moreover, since cooling towers can infect each other no single tower can be identified as the root cause of this outbreak.” Dr Humphrey said.

The study had been analysed by a team of scientists in Wellington who had prepared a detailed report.

‘The report identifies that the clusters concentrate on an area emanating outwards in a funnel shape from the southwest in a north-easterly direction.’

‘The study has taken into consideration the prevailing wind direction over the course of the outbreak.”

Unfortunately, the small number of cases means that the clusters are still only supportive of the theory, as the cluster formation is not statistically significant.

Dr Humphrey said that he is satisfied that all companies with positive results so far have cooperated with the investigation team.

“I am satisfied that all of the cooling towers positively identified so far have taken appropriate action and do not constitute a public health risk.”

Some of these companies are working with the industry groups, Christchurch City Council, the District Health Board and others to develop stricter protocols to monitor and treat cooling towers.

“This is an essential step in preventing this kind of Legionnaires outbreak in the future,” said Dr. Humphrey.

Ends.

Vivienne Allan
Communications Manager
0275-314-796