Controlling Legionella Begins With an Effective Water Management Program

May 6, 2022

Recent instances of Legionnaires' disease in the United States emphasizes the need for water management administrators to implement more effective control strategies

About the author:

Ron Misiunas is director - upper Midwest for Microbac. Misiunas can be reached at [email protected].

Legionnaires' disease is caused by Legionella, a common waterborne bacterium, and is manifested in humans through severe pneumonia (lung inflammation). Individuals most susceptible to legionellosis are people with chronic lung disease, such as emphysema and chronic obstructive pulmonary (COP) disease, individuals who have a weakened immune system from diseases like cancer or diabetes, current and former smokers, and people over the age of 50.

Legionella Disease: By the Numbers

Annually, Legionnaries' disease is responsible for more deaths than any other reportable waterborne disease nationwide. From 2009 to 2010, 58% of all drinking water-related outbreaks were caused by Legionella. Over 7,000 people contracted Legionella in 2017, a more than five-fold increase in the number of cases since 2000. In 2018, the CDC, in a consolidation of state health data, reported that more than 10,000 cases of Legionnaires' disease occurred nationwide.

A number of scientific watchdog groups, however, believe that Legionnaires' disease is underdiagnosed in the U.S., causing its true incidence to be greatly underestimated. The National Academies of Sciences, Engineering and Medicine, a private and non-profit institution committed to advancing science worldwide, has stated that as many as 70,000 cases of legionellosis could be occurring annually in the U.S.

The financial toll of Legionnaires' disease on affected individuals can be considerable. For one patient alone, the estimated hospitalization cost for legionellosis is roughly $38,000. Each year in the U.S., medical insurers dispense over $140 million in hospitalization claims for Legionnaires' disease treatment.

Ripped from the Headlines

Intensive media coverage of Legionella outbreaks has played a significant role in educating the general public on the prevalence, impact and ramifications of this problematic organism. 

One of the most highly publicized outbreaks occurred in 2015 when more than a dozen U.S. veterans died and many more were sickened by Legionella at a Quincy, Illinois, veteran’s home. In 2018, three people died and 11 became ill due to Legionella outbreak at the University of Wisconsin Hospital (Madison). In 2014 and 2015, an outbreak of Legionnaires' disease killed 12 people and sickened at least 87 people in Flint, Michigan, making it one of the largest outbreaks of Legionnaires' disease in American history.

Where is Legionnella Typically Found?

Legionella are typically found naturally in freshwater environments, such as lakes, rivers and other bodies of water, but usually in low numbers. When left to grow and proliferate in human-made water systems, however, the outcomes of Legionella infection can be ominous. By far, the most common form of transmission of legionellosis is the inhalation of contaminated water aerosols.

Legionella outbreaks are most commonly associated with buildings or structures that have complex water systems, such as hospitals, long-term care facilities, hotels, senior living multiplexes, resorts and cruise ships. According to the Centers for Disease Control and Prevention (CDC), the most common sources of infection linked to the dispersion of aerosols include:

  • Decorative fountains;
  • Cooling towers (structures that contain water and a fan as part of centralized air cooling systems for building or industrial processes);
  • Showerheads;
  • Electronic and manual faucets;
  • Non-steam aerosol-generating humidifiers;
  • Ice machines;
  • Hot tubs that are not drained after each use; and
  • Large plumbing systems.

Centrally installed misting systems, which are widely used in retail grocery stores to enhance the appearance of fresh produce, have also been identified as a potential source of infection by a number of health agencies. 

Preponderance of Problems

To help protect the public from the health risks posed by Legionella contamination, water management authorities are urged to work closely with environmental groups, government regulators and public health agencies to mitigate occurrences. 

Many Legionella outbreaks, according to scientific experts, are caused by environmental deficiencies or gaps related to process failure, human error, equipment repairs or unmanaged external events, such as power outages. 

A preponderance of these problems, they contend, could be prevented by adhering to four basic principles:

  1. Maintain water temperatures outside the ideal range for Legionella growth.
  2. Prevent water stagnation.             
  3. Ensure adequate disinfection.
  4. Maintain devices to prevent sediment, scale, corrosion, and biofilm, all of which provide a habitat and nutrients for Legionella

Guidance and Standards

Last year, ASHRAE, a non-profit organization that develops standards for the design, manufacturer and maintenance of building systems, released an updated version of its “Managing the Risk of Legionellosis Associated with Building Water Systems” guideline. The standard provides water management teams with direction on how to control the spread of legionellosis, such as utilizing a risk management process, and guidance to develop elements that are essential in an effective water management plan (i.e., tracking water use). 

Seeking to provide builders with guidance to reduce the risk of Legionella growing and spreading within their water system and devices, the CDC released a revised publication of its “Developing a Water Management Program to Reduce Legionella Growth & Spread in Buildings” tool kit this past June. 

The extensive CDC kit employs illustrations, flow charts, surveys and other interactive tools to help users build and maintain an effective water management program. Achieving this objective entails a multi-step, continuous process consisting of the following steps:

  1. Establish a water management program team, including names, titles, contact information, and roles on the team.
  2. Describe the building water systems.
  3. Identify areas where Legionella could grow and spread (e.g., hot tubs, decorative fountains, cooling towers).
  4. Decide where control measures should be applied and how to monitor them.
  5. Establish ways to intervene when control limits are not met.
  6. Make sure the program is running as designed and is effective, including verification steps to show that the program is being followed as written and validation to show that the program is effective.
  7. Document and communicate all activities.

Due to their importance in assuring public health, controlling Legionella in the nation’s hospitals is given special consideration throughout the CDC guidance document. Since 2017, the Centers for Medicare and Medicaid have required hospitals and healthcare facilities to develop policies and water management plans to inhibit the growth of Legionella in water systems and deter healthcare-associated infections. 

In recent years, recommendations requiring hospitals and long-term health facilities to monitor Legionella in environmental water samples has been frequently and widely addressed at scientific forums and symposiums across the country. 

Positive Sign of Progress

As a constructive sign of progress in the fight against Legionella, water management programs have become an industry standard for large buildings in the U.S., according to the CDC. Building an efficient and effective program, however, is not an easy task. Without hesitation, scientific groups and regulatory agencies typically urge water management administrators to work closely with qualified and reputable organizations to help mitigate the growth and spread of Legionella in their systems. 

About the Author

Ron Misiunas