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More than 40 years after its discovery, it shocks me to say that the number of reported cases of Legionnaires’ Disease in the United States has been rising since 2003. According to a recent report from the Centers for Disease Control and Prevention (CDC), the increase has accelerated in recent years (Barskey 2022).
This disease is a severe, often lethal, form of pneumonia. It is most often caused by the bacterium Legionella pneumophila. It is common for patients with Legionnaires’ Disease to be admitted to the intensive care unit, and some will suffer long-term, impaired health-related quality of life. Learn more from survivors of Legionnaires’ Disease at www.legionella.org.
Each year, an estimated 10,000 to 18,000 people are infected with the Legionella bacteria in the United States. The CDC speculates that the causes of the increase in Legionnaires’ cases could be due to weather changes, aging water system infrastructure, aging population and better case detection.
Where are these people being exposed to Legionella? We know that potable water is the primary source of transmission for these deadly bacteria — especially the warm water systems of large buildings such as hospitals. The next time you use a faucet or shower, sit next to a decorative water feature or hot tub at a hotel, or feel the mist coming off a cooling tower, you might wonder, “Could I have just been exposed to Legionella?”
If you experience a high fever, cough and have trouble breathing within two to 10 days, see your physician to rule out pneumonia caused by Legionella.
Some say our buildings are designed to grow Legionella bacteria. The warm temperatures in our hot water systems and cooling towers are ideal for microbial growth. Miles of pipe, often full of corrosion, scale and slime (biofilm), provide Legionella and other waterborne pathogens with all they need to grow. In fact, I say they are having a party in your piping!
How common is Legionella in water systems? About half of large buildings, including hospitals, are colonized by Legionella. Is your building in that half? Here’s how to assess and address risk:
1. Test for Legionella.
2. Determine what kind of Legionella is in your water system. Is it the deadliest type?
3. Act to prevent cases by creating and implementing a water safety and management plan, such as this one by the International Association of Plumbing and Mechanical Officials, the “Manual of Recommended Practice for: The Safe Closure and Reopening of Building Water Systems.”
It is important to select a testing method and laboratory to optimize testing accuracy. The CDC has guidance for selecting a laboratory; you can learn more about testing at Pace Labs.
Better Water System Management
According to the CDC, “the key to preventing outbreaks is good management of building water systems.” In a 2016 report, CDC states that outbreaks have occurred because of process failures (65 percent), human errors (52 percent), equipment failures (35 percent), external conditions (35 percent), or a combination of these (48 percent) (Garrison 2016).
The CDC recommendation is for building owners and managers to “determine if their building water systems are at increased risk for Legionella growth and spread. If so, they should develop and use a Legionella water management program, according to industry standards,” such as ASHRAE Standard 188-2021, Legionellosis: Risk Management for Building Water Systems, and ASHRAE Guideline 12-2023, “Managing the Risk of Legionellosis Associated With Building Water Systems.”
Successful water management requires at least one member of the program team to be knowledgeable about the building water systems as they relate to the risk of Legionnaires’ Disease. One way to become knowledgeable is to become certified in the ASSE/IAPMO/ANSI 12080 Standard: Professional Qualifications Standard for Legionella Water Safety and Management Personnel. This is a live virtual training over three days, or you can take a self-paced online course.
I wish I could tell you that simple maintenance and engineering controls will prevent Legionella from growing and spreading in your building and protect your building occupants.
Simple maintenance such as flushing hot water tanks, cleaning aerators or flushing or maintaining a hot water tank at 140 F does not prevent Legionella from happily growing downstream in the building water distribution system. Although often cited as a remediation approach, removing dead legs won’t solve your Legionella problems, either.
Smart Plumbing Design
What have we learned about faucets, showers and sink drains that contribute to the growth of waterborne pathogens and infections, particularly in health-care facilities?
Contributors to microbial growth include stagnation due to low use, water-saving measures such as low-flow fixtures and nontouch electronic sensor faucets, and drains that become reservoirs for pathogens. Certain materials within the faucet can also contribute to growth (Cullom 2023; Volling 2020; Yapicioglu 2012).
Future design considerations should minimize:
Surface area in contact with water;
Stagnant mixed hot and cold water volume;
Presence of plastic or elastomeric materials.
What if smart plumbing design teamed up with infection prevention to crash the Legionella and waterborne pathogen party in our piping systems? Smarter designs are already here to help manage the risk of infection due to Legionella and waterborne bacteria.
There are antimicrobial design features and materials. Showerhead design and flow can reduce aerosolization. Stagnation can be mitigated with automatic flushing faucets and draining shower systems. Flush cycles can be programmed and controlled via smartphones. Reduce water age, and you can improve water quality.
In health-care facilities, patients have been infected with the same bacteria inhabiting the sink drain via splash, aerosolization or leaking. These bacteria include Pseudomonas aeruginosa and antibiotic-resistant bacteria such as Klebsiella pneumoniae. New approaches to this problem include self-disinfecting sink drains and a drain barrier system with an internal washing system to prevent biofilm accumulation (BIOREC in Lauta, Germany, and Physiclean.com).
Can smart plumbing advances reduce infections? I am optimistic that innovative plumbing design will be an integral part of effective water management to prevent infections due to Legionella and waterborne pathogens. Now go out there and crash that party in the piping!
References:
Barskey AE, Derado G, Edens C. “Rising Incidence of Legionnaires’ Disease and Associated Epidemiologic Patterns, United States, 1992-2018.” Emerg Infect Dis. 2022 Mar;28(3):527-538. doi: 10.3201/eid2803.211435. PMID: 35195513; PMCID: PMC8888234.
Cullom A, Spencer MS, Williams MD, Falkinham JO 3rd, Brown C, Edwards MA, Pruden A. “Premise Plumbing Pipe Materials and In-Building Disinfectants Shape the Potential for Proliferation of Pathogens and Antibiotic Resistance Genes.” Environ Sci Technol. 2023 Dec 19;57(50):21382-21394. doi: 10.1021/acs.est.3c05905. Epub 2023 Dec 10. PMID: 38071676.
Garrison LE, Kunz JM, Cooley LA, Moore MR, Lucas C, Schrag S, Sarisky J, Whitney CG. “Vital Signs: Deficiencies in Environmental Control Identified in Outbreaks of Legionnaires’ Disease - North America, 2000-2014.” MMWR Morb Mortal Wkly Rep. 2016 Jun 10;65(22):576-84. doi: 10.15585/mmwr.mm6522e1. PMID: 27281485.
Volling C, Ahangari N, Bartoszko JJ, Coleman BL, Garcia-Jeldes F, Jamal AJ, Johnstone J, Kandel C, Kohler P, Maltezou HC, Maze Dit Mieusement L, McKenzie N, Mertz D, Monod A, Saeed S, Shea B, Stuart RL, Thomas S, Uleryk E, McGeer A. “Are Sink Drainage Systems a Reservoir for Hospital-Acquired Gammaproteobacteria Colonization and Infection? A Systematic Review.” Open Forum Infect Dis. 2020 Dec 8;8(2):ofaa590. doi: 10.1093/ofid/ofaa590. PMID: 33553469; PMCID: PMC7856333.
Yapicioglu H, Gokmen TG, Yildizdas D, Koksal F, Ozlu F, Kale-Cekinmez E, Mert K, Mutlu B, Satar M, Narli N, Candevir A. “Pseudomonas aeruginosa infections due to electronic faucets in a neonatal intensive care unit.” J Paediatr Child Health. 2012 May;48(5):430-4. doi: 10.1111/j.1440-1754.2011.02248.x. Epub 2011 Nov 16. PMID: 22085434.
Dr. Janet E. Stout, PhD, is the founder of Special Pathogens Laboratory, A Pace Laboratory. An infectious disease microbiologist, Dr. Stout is recognized worldwide for pioneering research in Legionella. Her expertise includes detection, prevention and control strategies for Legionnaires’ disease in building water systems. She initiated the development of the ASSE Standard 12080.