A Focus on Legionella Testing
In the summer of 1976, an outbreak of pneumonia occurred among people who attended an American Legion convention in Philadelphia. These individuals who developed illnesses were said to have 'legionnaires’ disease. There were 182 documented cases, with 29 deaths. By early January 1977, the disease-causing microorganism was isolated and a new family of bacteria, the Legionellaceae, was discovered. In 1979, the bacterium that caused the Philadelphia outbreak of Legionnaires’ disease was classified as Legionella pneumophila.
Legionnaires' Disease in New Zealand
There were almost 250 notified cases of Legionellosis or Legionnaires' disease in New Zealand last year. However, the number of notifications in New Zealand is lower than the number of positive laboratory results and it can be safely assumed that the actual incidence of legionellosis is much higher than notified.
Legionella bacteria are common in the environment and can found in domestic hot water systems, swimming pools/spas, industrial cooling towers, potting mix or compost etc.
Legionella in Cooling Towers
WorkSafe New Zealand has recently released a fact sheet to provide advice on preventing Legionnaires' disease aimed at businesses or undertakings that have or operate cooling towers or evaporative condensers (cooling plant).
New Zealand has concentrated on the testing of cooling towers associated with air conditioning systems as the primary source of Legionella related illness and in April 2004 the Building Industry Authority (BIA) (now part of the Department of Building and Housing) amended the draft compliance schedule in the New Zealand Building Code handbook to specify more frequent testing. This more rigorous testing regime for cooling towers is based on the current Australian-New Zealand Standard, AS/NZS 3666.3. It expands on the current requirement of a monthly bacteriological testing of water in cooling towers, by also requiring a specific Legionella bacteria test each month.
Legionella in soil, compost and potting mix
Another species called Legionella longbeachae, which occurs in soils, composts and potting mixes, has recently been found to cause illness in some people.
WorkSafe NZ has also recently released a fact sheet that provides advice on how you can keep your workers healthy if their work involves handling soil, compost or potting mix.
Producers and sellers of potting mix and compost should strongly consider a regular testing program in order to monitor the risk your product is posing to you’re the purchasers of your product.
Other Common Sources of Legionella
Legionella species also live happily in warm water circulation systems found in retirement homes, hospitals, and swimming pool complexes. It can also live
in domestic and hotel spa pools, as well as hot water cylinders that are not set at the correct temperature.
We also urge the regular testing of warm water circulation systems in retirement homes and hospitals and for operators of swimming pools to consider this test also.
We routinely test Legionella in the following matrices:
| Cooling Tower water Recycled warm water systems Soils and compost Swimming Pools |
Please see our Industrial Water Testing page or refer to our Legionella brochure for more information
