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  • Pilar G. Burkhard

So, what's the deal with Legionella?

Legionella Background

Legionella was first discovered in 1976 after several attendees of an American Legion conference in Philadelphia died unexpectedly with pneumonia-like symptoms. The large outbreak was determined to be caused by Legionella pneumophila bacteria which was found in high concentration in the hotel’s cooling tower. The resulting infection, which caused 182 infections and 29 deaths at the conference, is now what we refer to as Legionnaires’ disease or Pontiac fever.

The Bellevue-Stratford Hotel, site of the fist known outbreak of Legionnaires' Disease.

Since 1976, Legionnaires’ disease has made headlines across the country. Some of the more notable instances include the 2015 outbreak in Bronx, NY from a cooling tower leading to 138 cases and 16 deaths, and the 2017 outbreak at Disneyland in Anaheim where dirty cooling towers infected 22 people, killing one.

Legionella bacteria is ubiquitous in freshwater such as lakes and streams at low concentrations. However, in human-made heating and cooling systems, Legionella has the potential to amplify to a point of public health concern. Legionella bacteria transmits through water aerosols such as mist or spray. Therefore, locations such as showerheads, sink faucets, cooling towers, hot tubs, and fountains are potential sources for human infection.

L.pneumophila serogroup 1 and serogroup 2-14 are responsible for most hospitalizations. However, there are over 100 species of Legionella which have the potential to cause harm. Therefore, any positive detection of Legionella should be taken seriously.

Why should we care about Legionella?

Legionnaires’ cases have been on the rise in the United States over the past few years. According to the CDC, over 10,000 cases were reported in 2018 alone, compared to just over 1,000 cases in 2002. With more testing capabilities and a higher focus on public health, these numbers are predicted to increase, along with stricter regulations.

Crude incidence rates of reported confirmed cases of Legionnaires’ disease by year—NNDSS United States, 2000–2017.

Immune compromised individuals, such as people over 50 years old, current or former smokers, cancer patients, or anyone with a chronic lung disease are most at risk from contracting Legionnaires’ disease. Legionnaires’ disease has an average mortality rate of 15% in these high-risk groups. Therefore, healthcare facilities need to take extra precautions in limiting the spread of Legionella throughout their large water systems.

For these reasons, the Centers for Medicare & Medicaid Services (CMS) and the Centers for Disease Control and Prevention (CDC) consider it essential that hospitals and nursing homes have a water management program that is effective in limiting Legionella and other waterborne pathogens from growing and spreading in their facility.

Water Management Plans

Because of increasing regulations and focus on public health, now, more than ever, having a water management plan (WMP) for any large facility is vital. A WMP identifies areas of risk (possible Legionella growth and transmission sites) and implements actions to minimize the risk to human health. The detailed plan is a multi-step and continuous process that is reviewed at least annually if no event triggers an earlier review.

For facilities, the WMP team should understand accreditation standards and licensing requirements, have expertise in infection prevention and infectious diseases, and should include personnel trained in risk and quality management. Building owners should always consult a trained professional with experience in WMPs to ensure all bases are covered and personnel are well trained.

Verification of the WMP is critical to ensure the facility is following the plan and has documentation to prove it. The best way to verify a WMP is by testing for Legionella regularly by an accredited lab. This not only proves your plan is effective, but it also protects a facility from future liability should anyone contract Legionnaires’ disease.

Chem Inc. Lab Certifications

Chem. Inc.’s analytical lab is both CDC Elite and EMLAP certified for Legionella testing.

CDC Elite is a certification, run by the Centers for Disease Control and Prevention, where laboratories can test their Legionella isolation technique against standardized samples. Labs must pass proficiency testing twice a year to maintain this certification.


The Environmental Microbiology Laboratory Accreditation Program, is specifically for labs identifying microorganisms. This certification is acquired through maintaining a comprehensive quality control measures and

documentation according to ISO 17025. Our lab is audited on an annual basis by ANAB (ANSI National Accreditation Board).

With these two certifications, Chem., Inc. can ensure our customers are receiving top quality testing and documentation.

Want more help?

Our team at Chem., Inc. has years of experience dealing with Legionella and are here to help. If you have questions or would like to get a testing quote, please don’t hesitate to reach out. Our goal is to make understanding and dealing with Legionella as easy as possible.

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