Legionnaires' Disease

Legionnaires' disease is an infection caused by the bacteria Legionella pneumophila. It was first identified in 1976 following an outbreak of pneumonia among persons attending an American Legion convention in Philadelphia. Approximately 10,000 to 15,000 people in the United States get legionnaires' disease every year. More may be infected and either have mild symptoms or not feel ill. 5- 15% of known cases have been fatal.

The bacteria are commonly found in a variety of natural and man-made aquatic environments. The bacteria particularly like warm (95-115 ° F) stagnant water. These conditions can be met in some plumbing systems, hot water tanks, cooling towers and evaporative condensers of large air conditioning systems, whirlpool spas, showers, creeks, and ponds. Soil has been suspected as a reservoir also. Home air conditioning units generally use cool water and thus are not a major source of the bacteria. Legionnaires' disease is transmitted by inhaling aerosols containing the bacteria. This can occur at home, the workplace, hospitals, and public locations. There is no evidence of the infection being spread from person to person.

People of any age may get Legionnaires' disease, but there are some people who are at higher risk. Legionnaires' disease most often affects middle-aged and older persons. People who smoke cigarettes or have chronic lung disease are particularly at risk. Other high-risk groups include persons whose immune system is suppressed by diseases such as cancer, or suppressed by medications, patients on kidney dialysis, diabetics, or patients with AIDS.

Symptoms of Legionnaires' disease include fever, chills, and a cough that may be dry or produce sputum. Some patients have muscle aches, headache, tiredness, and loss of appetite. A chest x-ray may show pneumonia. Legionnaires' disease is diagnosed by special tests. These can include finding the Legionella bacteria in sputum, finding Legionella antigens in urine samples, and looking at antibody levels in blood samples.

Legionnaires' disease is treated with antibiotics. Usually erythromycin or rifampin is used. Other drugs are available if a patient can't take erythromycin.

Legionnaires' disease can be prevented through routine maintenance of cooling towers and air conditioners, chemical treatment with biocides, and minimizing water stagnation. Systems should be kept clean. High-efficiency mist eliminators on cooling towers will prevent proliferation of the Legionella bacteria.

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Questions regarding Legionnaire's disease may be address to Michelle Ferguson or call 831-6366.

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