New testing technology for preventing Legionella outbreaks in hotels and casinos


by Paul Lem, M.D.

Legionnaires’ disease, a severe pneumonia with a death rate ranging between five and 20 percent, has long been associated with the hospitality industry.1 The first known Legionnaires’ outbreak was at the Bellevue-Stratford Hotel in Philadelphia, where the American Legion was holding its 1976 convention. The disease is caused by inhaling water vapor in the air that has been contaminated with Legionella bacteria. In hotels and casinos, sources of contamination include cooling towers, humidifiers, hot tubs, decorative fountains, and showers. The consequences of outbreaks are severe, including deaths, multi-million dollar lawsuits, and extremely bad publicity.

Highly-publicized outbreaks

According to the U.S. Centers for Disease Control and Prevention (CDC), people at higher risk of contracting Legionnaires’ are 50 years of age or older, smokers, and those with underlying medical conditions such as chronic lung disease or immunosuppression.2 These high-risk groups are common visitors to hotels, casinos, and tourist attractions. There have been many highly-publicized outbreaks in the past 12 months at destinations including Disneyland, Graceland, the Rio Hotel-Casino in Las Vegas, and the new $2.7-billion dollar Parisian Macao casino.3,4,5,6

To prevent outbreaks, it is worth considering the cautionary example of the Illinois Veterans Home in Quincy (IVHQ), where Legionnaires’ has contributed to the deaths of 13 people and sickened dozens more in the past three years. In response, the administration installed a $6.4-million water treatment plant and implemented a strict schedule of disinfection, flushing, and filtering, including a thermal eradication procedure known as “super heat and flush”.7,8 In addition, IVHQ spent more than $1 million on Legionella culture testing, which involves shipping a water sample to a laboratory and growing it on a petri dish.9 Despite these extraordinary measures, IVHQ continues to experience outbreaks. In desperation, a preliminary report has called for the construction of a new facility costing as much as $278 million.

Ineffective testing method

There are two major problems with IVHQ’s approach to preventing Legionella outbreaks. First, thermal eradication is one of the most difficult and least effective means of controlling the growth of Legionella bacteria.10 Second, and more importantly, Legionella culture is known to be inaccurate. For example, the CDC conducted a proficiency study of 20 ELITE-certified culture labs and found that, on average, they underestimated the actual amount of Legionella by 17-fold and results between labs differed by six-fold.11 Another problem is culture takes 10-14 days to get a result. This time lag is problematic because Legionella can grow to outbreak levels in as few as seven days.12,13 This is why testing regulations for New York City and Canadian government buildings require both weekly and monthly testing.14,15

New technology solves problem

To solve the limitations of culture, the first on-site Legionella DNA test was commercialized in November 2017.16 The test is called the Spartan Legionella Detection System and it consists of a coffee-cup-sized DNA analyzer and single-­use disposable test cartridges. It uses a Nobel-Prize-winning chemistry called quantitative Polymerase Chain Reaction (qPCR) to determine the amount of Legionella in a water sample in 45 minutes. The test is the 2018 winner of the HVAC industry’s top innovation award for Indoor Air Quality (IAQ), as judged by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE).

The Canadian government used the Spartan Legionella test for a 12-week study of 51 cooling towers. In the study, Spartan’s test detected levels higher than 10 bacteria/mL in 39 percent of towers, including levels higher than 100 bacteria/mL in 8 percent of towers.17 These towers were being tested monthly with culture, but the problem was that culture had a false negative rate of 62.5 percent due to bacterial degradation during shipping. In fact, one tower had levels higher than 1,000 bacteria/mL, but culture testing completely missed the contamination. To put these levels into perspective, the World Health Organization (WHO) has stated that Legionnaires’ disease outbreaks typically occur at levels higher than 100 bacteria/mL.1

Preventing Legionella outbreaks

The Petri dish for bacterial culture was invented by Julius Richard Petri in 1887. Culture testing takes weeks to get a Legionella result and has been proven to be inaccurate. This is a major reason why Legionnaires’ outbreaks continue to occur despite regular testing. Now there is a better solution: on-site Legionella DNA testing that provides results in minutes and is highly accurate. It is possible to identify sources of contamination on site and disinfect them before the bacteria grow out of control. This is great news for the hospitality industry and all of us who enjoy traveling.


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