Commercial HVAC Equipment

Legionnaires’ disease: A layman’s guide to what you need to know about the illness

Tuesday, September 1 2015 10:14 AM
By Jon Goering

Bacterium Legionella pneumophila on surrealistic space background, model of bacteria, microbes, microorganisms, bacterium causes Legionnaires disease. Elements of this image furnished by NASA


This summer's outbreak of Legionnaires’ disease in New York City and the most recent cases in Illinois and California - all leading to the death of 16 people and the sickening of many more – reminds us that better understanding the illness and inhibiting its ability to harm remains critical.

In this blog we will define Legionnaires’ disease and examine its history, environments, transmission and symptoms and review the recent outbreaks. In addition, we will outline ways to reduce Legionella growth at your building (the main focus being on cooling towers as they are more likely to be found in commercial and industrial settings) and include a sample letter to share with your employees if an outbreak or potential outbreak occurs at your workplace. Finally, we’ll look at ASHRAE’s newly-released standard addressing Legionnaires’ disease.

What is Legionnaires’ disease, and why the name?

Legionnaires’ disease borrows its name from the bacteria that causes it – Legionella. While the bacteria has existed for ages, the disease was named in 1976 to honor the more than 200 American Legion members and visitors who began suffering from a type of pneumonia after attending a convention in Philadelphia, where some eventually died. It wasn’t until after the outbreak, however, that health officials discovered Legionella bacteria’s existence in the affected people’s lung tissue.

What is Legionella and how do I get exposed to it?

Legionella bacteria lives in low levels in the natural environment in places such as soil, lakes, streams, and ponds. Unnatural environments most likely to harbor Legionella - and ideal for bacterial growth -include hot tubs, cooling towers, decorative fountains, drinking water systems and hot-water tanks, where water temperatures between 90 and 105 degrees F exist, although it can survive in a wide range of temperatures (61 degrees F to 147 degrees F).

Legionella potentially sickens people when they inhale water droplets containing the bacteria carried through the air in the form of a mist or vapor or drink water containing the bacteria. However, most people do not become ill after being exposed to Legionella, and there is no vaccine for it. Experts estimate between 8,000 and 10,000 cases of Legionnaires’ disease occur annually in the United States, with 10 percent being fatal.

Legionella also can lead to Pontiac Fever, which exhibits flu-like symptoms as well (fever, headache, fatigue, chills, nausea, muscle and joint pain). While no deaths have been reported from Pontiac Fever, experts say it will occur in about 90 percent of people exposed to Legionella but with a much shorter incubation period, i.e. exposure to appearance.

What are the Symptoms?

While not everyone infected with Legionella bacteria exhibits the same symptoms, a person infected at first appears to have the flu, and after several more days pneumonia-like symptoms may appear. It can take two days and up to two weeks for symptoms to begin after exposure. Symptoms include:

  • Cough
  • Shortness of breath
  • High fever (102 to 105 degrees F)
  • Muscle aches
  • Headaches
  • Chills
  • Chest pains

Factors increasing someone’s risk of getting Legionnaires’ disease include old age, organ transplants, heavy smoking, a weakened immune system, other diseases and the heavy alcohol consumption. Early treatment improves one’s chances of recovery and likely includes antibiotics.

What happened in New York City, Illinois and California this summer?

As stated earlier, 12 people died in New York City, and more than 120 became infected with Legionnaires’ disease in July and August. Experts say a cooling tower(s) appears to have caused the Legionnaires’ disease outbreak, as five out of the 17 towers tested contained Legionella bacteria. Most recently, in Quincy, Illinois, four patients at a veteran’s home died of the disease and 25 others have tested positive for Legionella. And at San Quentin State Prison in Northern California, six inmates have been infected with the disease, and another 73 inmates were being treated for respiratory illness but have not been diagnosed with Legionnaires’ disease.

How Do I Prevent It?

Experts say controlling Legionella’s growth in a cooling tower can be done through frequent cleaning, water treatment, minimizing stagnation and routine inspections. An HVAC system’s size dictates how frequently cooling tower inspections should be conducted in person, with larger systems requiring a daily check and smaller systems weekly or monthly. An added benefit of proper cooling tower maintenance can reduce energy and equipment costs. Experts recommend these steps:

Routine Inspections – these should be conducted daily, weekly or monthly, depending on your system size. Chemical and microbial tests should be conducted per your water treatment expert’s recommendations.

Cleaning – cooling towers should be drained, cleaned and disinfected at least once a year to remove dirt, sediment, scale and organic material, which can help Legionella grow and thrive. OSHA recommends this should be done at the beginning and end of the cooling season.

Water Treatment – a chemical treatment program should be ongoing in order to make your system inhospitable to Legionella. Experts recommend using a descaler in conjunction with biocides as the descaler removes scale, allowing the biocides to address Legionella more effectively.

Minimize Stagnation – identify areas where water can stagnate, such as storage tanks, unused pipe sections (dead legs) or faucets. If possible, eliminate dead legs, replace gaskets (bacteria receive nutrients from them) and flush lines frequently. Avoid exposing water-storage tanks to sunlight.

ANSI/ASHRAE Standard 188-2015

The new ANSI/ASHRAE Standard 188-2015, Legionellosis: Risk Management for Building Water Systems, was released this summer, intended for building owners and managers and those in the industry who work with building water systems. Some of the Standard’s requirements include:

  • Risk management requirements for buildings and building water systems
  • Building owners form a Program Team to address Legionella/Legionnaires’ Disease
  • Building owners form a Water Management Program to ensure they comply with the new Standard, to include specific control measures
  • Documentation of activities

A copy of the new ASHRAE 188-2015 Standard can be purchased here.

While Legionnaires’ disease should be respected, considering its ability to sicken and in some cases cause death, preventative measures exist that can help eliminate the disease’s opportunities to infect. Implementing these measures at your facility, understanding the environments in which Legionella bacteria thrives and recognizing the disease’s symptoms and the importance of early treatment will help you reduce the risk of legionella in your building’s water system and protect your employees from illness.

For a sample letter and additional information you can use to inform employees in the event of a Legionnaires’ disease outbreak, click here.

For more information, please email Jonathon Goering by clicking here or call 316-265-9655.

Knipp Services works with commercial and industrial building owners to identify building solutions that can reduce downtime and increase the efficiency of their building. We provide services that enable building owners to have a high performance building.

Topics: Legionella, Legionnaires’ disease, New York City Legionnaires’ disease outbreak

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Center for Disease Control and Prevention


The Legionnaires’ Lawyer


Legionella: Drinking Water Health Advisory


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