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Legionnaire's Disease is a life-threatening form of pneumonia. It is caused by a bacterium called Legionella pneumophila that is commonly found in natural water sources -- rivers, lakes, etc. -- and may be found in cooling towers, condensers and whirlpool spas. In optimum conditions, the bacteria will multiply.
Legionnaires Disease received it's name when in 1976, many attendees of a convention of the American Legion in Philadelphia became sick with the same disease. Doctors now automatically screen for it whenever a patient presents with pneumonia systems.
Legionnaire's Disease is the most serious illness caused by this bacteria. Pontiac fever is a milder form and doesn't affect the lungs.
According to the CDC, Legionnaire's Disease hospitalizes between 8,000 and 18,000 people per year in the United States. It is expected, however, that the number of diagnoses is actually higher than this as many cases continue to undiagnosed or unreported. Five to fifteen percent of known cases have been fatal. Of those patients who contract the disease while in hospital, 50% die from it.
The Symptoms of Legionnaire's Disease
Because the symptoms of Legionnaire's Disease are so similar to pneumonia it is difficult to diagnose at first. Below is a list of symptoms that may not all occur at once and may not be experienced by all patients:
• High fever (104-105F);
• Chills;
• Dry cough (which may or may not include coughing up blood);
• Muscle aches;
• Headaches;
• General feeling of unwellness;
• Chest pain;
• Nausea;
• Vomiting;
• Diarrhea;
• Difficulty breathing;
• Pneumonia;
• Confusion;
• Disorientation;
• Hallucinations; and
• Loss of memory.
Symptoms tend to worsen during the first week or so, then improve after another week.
Risk Factors
Scientists and doctors have been able to determine that people can develop Legionnaire's Disease when they inhale small droplets of water that contain the Legionella bacteria. Since the vapor is inhaled, it goes into the lungs where the bacteria festers and infects.
Outbreaks happen when two or more people in an enclosed area contract the disease, for example, hospitals, office buildings, cruise ships and hotels.
So far there is no research to support that the disease is transferred from person to person.
Those over 65, who smoke or suffer from other chronic lung condition are at greatest risk, as are those who have weakened immune systems from cancer, diabetes, or kidney failure.
Diagnostic Tests and Treatment
A series of tests are conducted to try to confirm or deny the presence of Legionella pneumophila bacteria including:
• Arterial blood gases;
• Chest X-ray;
• Complete blood count;
• Liver function tests;
• Sputum culture; and
• Urine tests.
Treatment usually involves antibiotics which are started even before the tests come back with a result.
Prevention
To prevent the initial onset and potential spread of the disease, measures must be taken to kill the bacteria at the source before it can grow and fester and ingested. Cooling towers and condensers need to be inspected on a regular basis and thoroughly cleaned at least once per year. Cooling water should be treated regularly and, if possible, an automatic water treatment system installed to continuously control the quality of the water being circulated.
Any disinfectants must be compatible with the cooling water tower's systems. Fresh air intakes should not be built close to cooling towers to prevent aerosols from entering the ventilation system, and air filters should be inspected, cleaned and tested for leaks. Hot water tanks should also be cleaned regularly to avoid water stagnation -- a prime breeding ground for bacteria.
Sources: www.cdc.gov; www.hse.gov.uk (Health and Safety Executive); www.ccohs.ca (Canadian Centre for Occupational Health and Safety); www.nlm.nih.gov (U.S. National Library of Medicine and the National Institutes of Health.
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An effective way to combat Legionella growth in cooling towers basins is to continously clean and remove the suspended solids that settle in the basin, which prevents bacterial growth. Check out this article for more info -- http://blog.lakos.com/bid/32378/Recent-Legionella-Outbreaks-Stress-Need-For-Better-Prevention
January 5, 2010 - 9:58amThis Comment