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Dec 13 2017

Are Your Cooling Towers Harboring Legionnaires’?


Like a zombie rising from the grave, Legionnaires’ disease, that menace of 70s cruise ships and hotels is rearing its hideous head in the 21st Century.  Legionnaires’ is a severe form of pneumonia caused by an infection of the bacterium Legionella.  Since 2000, reported cases of Legionnaires’ have grown by almost four and a half times according to the CDC.  The initial outbreak, which took place in 1976 at a Philadelphia convention, sickened 221 people and killed 34.  Many of those convention attendees were members of the American Legion, hence the name Legionnaires’ disease.

Cooling Tower Incubators
Cooling towers have been host to the more frequently publicized outbreaks of the disease, with periodic outbreaks originating in the water systems of domestic buildings.  The troublesome pathogen, Legionella pneumophila, centuries old and common in nature, has undoubtedly been infecting humans for a while.  In 2015, the CDC reported 6,000 cases alone, which, because the disease is often underdiagnosed could be a vast understatement. 
“Most well-publicized outbreaks have been in cooling towers.”
How It’s Contracted
Legionella is contracted by inhaling water aerosols that contain the bacteria. Exactly how much bacteria is needed to induce infection is unknown, but experts agree that the numbers vary according to an individual’s health status, age, and other predisposing issues. According to the Centers for Disease Control and Prevention (CDC) in the US alone, there are between 8,000 and 18,000 cases of Legionnaires’ disease annually, and more than 90 percent of cases go unreported. People with compromised immune systems, respiratory conditions, and cancer are more likely to become infected.  Of those infected, an estimated 10 to 20 percent will die of the disease, and for individuals with compromised immune systems, the fatality rate is even higher.

Where It’s Found
Because Legionella bacteria occur naturally in soil and various waterways such as rivers and streams, they can successfully colonize manmade water handling and storage systems where they often find the ideal nutrition and temperature conditions to flourish. Legionella bacteria can also hide inside scale and sediment where they find protection from hot water and chemical disinfectants.
The conventional water and air-conditioning engineering methods used in recirculating cooling towers, air-conditioning chill coils and humidifiers, aquatic, water storage and distribution systems offer the potential for legionella to harm large numbers of people.  While the most reported, widespread cases of Legionnaires’ disease have originated from cooling towers, the likelihood that hot and cold domestic water systems may harbor legionella should never be underestimated. 

Preventive Measures
While no water treatment or maintenance system can completely and permanently eradicate the organism, merely being aware of the bacteria and working with your HVAC and plumbing systems professional on a solid preventive maintenance schedule can help circumvent an outbreak.
For more information on how to ensure the health of your HVAC and plumbing and piping systems…>>(Visit) 
Domestically Acquired Legionnaires’ disease: Two Case Reports and a Review of the Pertinent Literature
CDC, Mayo Clinic, 

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