LEGIONNAIRES' DISEASE

With the widely publicized outbreak of Legionnaire’s Disease in Minnesota, attributed to bacteria found in cooling towers, Owens felt it important to try to answer some of the commonly asked questions and explain what is really known about the disease. More importantly, this technical bulletin will point out how much is still unknown about this disease, its cause, and what can and should be done about it.

We approach this topic as a water treatment supplier and a service contractor involved in installing, operating, and maintaining cooling towers and other mechanical water systems which are potential sources of the bacteria identified as the cause of Legionnaires’ Disease. Any recommendations Owens makes with regard to the prevention of Legionnaires’ Disease are not to be construed as a guarantee that the disease will not occur.

Legionnaires’ Disease is a form of pneumonia caused by a bacterium called Legionella pneumophila. It was first identified in 1976 in Philadelphia with the outbreak of a strange pneumonia and several deaths among a group of American Legion members attending a conference—hence the name, Legionnaires’ Disease. The same bacterium was later traced back to a previously unknown pneumonia in 1947, and a second documented case of a legionella caused pneumonia in 1959. It is not a new disease. Speculation among researchers is that the proliferation of water cooled air conditioning systems beginning in the 1950’s has led to its increase.

Legionella is a freshwater, aerobic (oxygen-requiring) bacterium.  Believed to be widespread, nearly 100% of the lakes and rivers in the southeastern United States are contaminated according to one study.  However, there have been no known cases of Legionnaires’ Disease in that environment, most likely due to low concentration levels. In another study, 60% of hospitals surveyed were contaminated with legionella bacterium, but there was no correlated disease prevalence. Data such as these are what makes this disease so difficult to prevent. As with many common health problems, the mere presence of the bacterium does not necessarily indicate there will be a disease outbreak.

The most susceptible to the disease are the elderly and those with lower immunities. Typical symptoms include fever, chills, fatigue, diarrhea, headache, and muscle aches.  The disease is treated with antibiotics.  The average fatality rate is 15%. The disease is spread through the air via aerosol-producing devices. It has been associated with cooling towers, shower heads, whirlpool baths, and potable water systems. The bacterium has been found in ponds, creeks, soil, and standing water. In one instance it would found in standing water at a construction site. The incubation period for the disease is usually five to six days. There is no indication it is contagious.

So what can be done to prevent its occurrence? Unfortunately, often very little. Some researchers have advocated testing for the bacterium, but this can create a false sense of security. If the results are negative, the sampling could have missed the bacterium or it could develop between samples. If the tests are positive, it is not yet known what action can be taken to prevent further contamination or the chance of an outbreak of the disease.

The best advice from the experts is to try to minimize the bacterium’s ability to flourish and be transmitted. With cooling towers this means keeping them clean and using an effective biocide program. Locating outside air intakes away from the aerosol spray of cooling towers can help prevent its transmission. Also, standing water in air handling units or air streams should be eliminated. Finally, because of its widespread nature, people in susceptible categories should avoid working in and around these mechanical systems.

For answers to your questions or for addition information, please call your Owens representative or John Owens at (612) 854-3800.

Owens Companies Inc. 930 East 80th Street Bloomington, Minnesota 55420 Ph: 952.854.3800 Fax: 952.854.3769

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