Each year, between 8,000 and 18,000 people are hospitalized with
Legionnaires disease in the U.S. However, many infections are not diagnosed or reported.
Legionnaires Disease can have symptoms like many other forms of pneumonia, so it can be hard to diagnose at first. Signs of the disease can include: a high fever, chills, and a cough. Some people may also suffer from muscle aches and headaches. Chest X-rays are needed to find the pneumonia caused by the bacteria, and other tests can be done on sputum (phlegm), as well as blood or urine to find evidence of the bacteria in the body.
The likelihood of Legionella infection can be best reduced by good engineering practices in the operation and maintenance of air and water handling systems. Cooling towers and evaporative condensers should be inspected and thoroughly cleaned at least once a year. Corroded parts, such as drift eliminators, should be replaced. Algae and accumulated scale should be removed. These measures will not only control the growth of germs, but will also maintain operating efficiency. During cleaning operations in confined spaces, safety procedures for entry into confined spaces should be applied.
Cooling water should be treated constantly. Ideally, an automatic water treatment system should be used that continuously controls the quality of the circulating water.
The disinfectants commonly used in cooling towers are chlorine, dibromonitrilopropionamide, and ammonia derivatives called quaternary ammonium compounds. They appear to be effective in laboratory tests, but their value in practice has not been completely proven. It is important that any disinfectant used in a cooling tower water system be compatible with the tower's construction materials.
Fresh air intakes should not be built close to cooling towers since contaminated aerosols may enter the ventilation system. Air filters should be examined, cleaned and/or replaced periodically and tested for leaks. Cooling towers should be positioned so the drift or evaporate does not enter the fresh air intake. Hot water tanks, which might provide ideal conditions for the growth of Legionella, should be cleaned regularly. The water system should be flushed out on a regular basis to prevent the water from stagnating.