Taking a look at Legionella bacteria and its sources, impact

twoLegionellosis is a respiratory disease caused by Legionella bacteria. Sometimes the bacteria cause a serious type of pneumonia (lung infection) called Legionnaires’ disease. The bacteria can also cause a less serious infection called Pontiac fever that has symptoms similar to a mild case of the flu. The bacteria can be found in most water systems, and is fairly common. Below are a few pieces that discuss the bacteria and the disease.

Legionnaires’ disease: Can it be found in water systems? says that “it is important to note that Legionella can be effectively controlled. When controlled properly, the bacterium represents a minimal health risk and emergency actions should not be required. The key to preventing an outbreak of Legionnaires’ disease starts with the municipal water system.  Additionally, a good building water management plan, responsibly implemented, should control the bacteria from colonizing to dangerous levels within individual building water systems.”

Monochloramine for controlling Legionella in biofilms: how much we know? concludes that “The presence of Legionella within a biofilm makes eradication from water system very difficult. Among the antimicrobial agents, monochloramine (MC) seems to be more effective for decreasing Legionella within the biofilms in vitro as well as in model plumbing systems. As of to date there are no published reviews on this topic, a critical and comprehensive update on the progress in the field is necessary.”

Legionella Control in Institutional Water Systems suggests that “a residual of chlorine-based disinfectant is indispensable because it is effective against the majority of bacteria and viruses and other germs that commonly cause waterborne disease, and it provides continuing protection as water journeys from the treatment plant to your glass.”


·         Relationship between antibiotic- and disinfectant-resistance profiles in bacteria harvested from tap water.

·          Water heater temperature set point and water use patterns influence Legionella pneumophila and associated microorganisms at the tap

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