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Understanding Legionella
10 to 15000
25000
people are affected by the disease annually in the United States (Centers for Disease Control and Prevention)
cases have been reported by OSHA (Occupational Safety and Health Administration)
4000
deaths have been caused by the disease (OSHA)
WHAT IS LEGIONELLA?
Legionella bacteria is found in water. It causes Legionellosis. Since its identification in 1977, Legionnaires’ disease has been the subject of many investigations, reports and recommendations on how it is transmitted and how to properly control it. Considered mysterious when it was first documented, this infection can still lead to tragedy, despite our greater understanding of it.
WHAT IS LEGIONELLOSIS?
Legionellosis is an infection of the respiratory system caused by Legionella bacteria. The bacterium most frequently responsible for the disease, in more than 90% of cases, is Legionella pneumophila, with serogroup 1 being involved in almost 85% of infections.
Legionellosis manifests itself in two clinical forms: Legionnaires’ disease and Pontiac fever. Pontiac fever is a mild form of Legionnaires’ disease. It heals on its own after three to six days and is rarely diagnosed as a Legionella infection.
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HOW DOES IT SPREAD?
When conditions are favorable, Legionella can grow in many artificial environments, including domestic water systems and cooling circuits..
However, the mere presence of Legionella in water is not enough to cause disease. Aerosols carry bacteria into the lungs. Infection occurs when an individual inhales contaminated aerosols (microdroplets less than or equal to 5 μm, which is small enough to penetrate alveoli).