Le gionellosis

Legionellosis is an infection that is caused by the bacterium Legionella pneumophila. The disease has two distinct forms: legionnaires disease is the more severe form of the infection, which may involve pneumonia; Pontiac fever is a milder illness that develops from some hours to two days after initial infection and resolves spontaneously.
Legionellosis infection occurs after persons have breathed mists that come from a water source (e.g., air conditioning cooling towers, whirlpool spas, showers) contaminated with Legionella bacteria.

People may be exposed to these mists in homes, workplaces, hospitals, or public places. Legionellosis is not passed from person to person, and there is no evidence of persons becoming infected from auto air conditioners or household window air-conditioning units.

Patients with Legionnaires disease usually have fever, chills, and a cough, which may be dry or may produce sputum. Some patients also have muscle aches, headache, tiredness, loss of appetite, and, occasionally, diarrhoea. Laboratory tests may show that these patients' kidneys are not functioning properly. Chest X-rays often show pneumonia.
The bacteria reproduce to high numbers in warm, stagnant water (32°-40° C), such as that found in certain plumbing systems and hot water tanks, cooling towers and evaporative condensers of large air-conditioning systems, and whirlpool spas.

Legionnaires disease is believed to occur worldwide. It is estimated that approximately 10 to 15 thousand people contract it in the United States each year. An additional unknown number of people are infected with the Legionella bacterium but have only mild symptoms or no symptoms at all.

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Sources:
http://en.wikipedia.org/wiki/Legionellosis
Picture:
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