For this month’s episode of the ICC Pulse Podcast, the Code Council interviewed Dr. Janet Stout, a world-renowned expert on Legionella and Legionnaires’ disease. Dr. Stout, president and director of Special Pathogens Laboratory in Pittsburgh and a research associate professor at the University of Pittsburgh, talks about the dangers of Legionella, where it’s most prevalent and how those at risk can protect themselves. Click here to listen to the episode or subscribe on Apple Podcast or Google Play.


Whitney Doll, ICC Vice President of Communications: Can you give us a brief description of what Legionella is and some of the main issues surrounding it?

 Dr. Janet Stout:  Legionella is a bacteria that is naturally found in water. It has the capabilities of causing a life threatening pneumonia called Legionnaires’ disease. When I think of the main issues around Legionella, I think of the four D’s: discovery, diagnosis, denial and detection.

Discovery: Many may remember the case in 1976 where the American Legion delegates who stayed at the Bellevue Stratford Hotel in Philadelphia contracted a mysterious form of pneumonia. This was later determined to be a newly discovered disease with the newly identified bacteria, Legionella. After that, microbiologists tested and grew the organism at the Centers for Disease Control and Prevention (CDC).

Initially the outbreak at the Bellevue Stratford Hotel was linked to a cooling tower exposure; however, in 1982, we discovered that the water coming out of faucets and showers was the true source. Today, potable drinking water systems, particularly warm building water systems, are the most significant source of exposure for Legionella.

Diagnosis: The main issue with diagnosis is that many physicians don’t think about Legionella when they see a patient with pneumonia and often the diagnosis is missed.

Denial: People don’t think that there are any cases of Legionnaires’ disease or they believe that it’s very rare. Denial occurs because people prefer not to think about the fact that it could be coming from their own building water system.

Detection:  Whether it is within the patient or in the water, you have to go looking for it. Bruce Dixon, physician and former director of the Allegany Health Department, said, “If you don’t look for it, (Legionella) you won’t find it. If you don’t find it, you don’t think you have a problem. And, if you don’t think you have a problem, you don’t do anything about it.” That’s really the main issue about Legionella.

 Doll: How did you decide to go looking for it? How did you get involved in this research?

Stout: I was a graduate student at the University of Pittsburgh Graduate School of Public Health with a concentration in Infectious Diseases Microbiology. As a student, you go looking for a project. I was lucky enough to go to the Pittsburgh Veterans Affairs Medical Center. There I met Dr. Victor Yu and his team of researchers who were trying to figure out the source of the Legionnaires’ disease within their patients. Our work was published in the 1982 issue of The New England Journal of Medicine. With more than 30 years of infectious disease study and research in Legionella, I now consider myself a “Legionellogoloist.”

Doll: What is the connection between building safety and Legionella? How do building codes come into play?

 Stout: Potable water systems are the primary source of exposure, which are the building water systems. It’s important to know that many of us are exposed to Legionella bacteria. Its presence alone is not exactly a safety issue, rather a combination of factors threaten safety.

Within the family of Legionella, there are many members – more than 60 species. The one that caused the original American Legionella outbreak, Legionella pneumophila serogroup 1, continues to be the primary cause of Legionnaires’ disease. We are particularly concerned with this member of the Legionella family. It is found in the water and gets to the lungs of the individual, which happens by inhaling mist or drift from a cooling tower or aspiration of water by drinking it.

Finally, certain individuals are more susceptible to Legionella. Typically, people who have specific conditions, including smokers, diabetics, those treated for cancer and hospitalized patients (in particular transplant patients) are the most vulnerable.

People need to understand that this is problematic and not something to ignore. In 2015 in Bronx, N.Y., there was a huge outbreak with 138 cases of Legionnaires’ diseases, which resulted in 16 deaths. Also, in addition to the lead problems in Flint, Mich., there was an outbreak of 90 cases of Legionnaires’ disease that were associated with the changes in the water that served all of the buildings within Flint.

Due to the outbreaks, there have been new standards and regulations. ASHRAE developed a new standard in June 2015 for the building industry. The purpose of the standard was to help guide people through risk management and buildings assessment in order to help minimize the chance of Legionnaires’ disease occurring because of exposure to Legionella from devices such as cooling towers or the water distribution system.

While the ASHRAE standard is a voluntary standard, after the Bronx outbreak, New York City and New York state issued a public health law, which was the first requirement for Legionella testing in the United States. During the summer of 2017, the Centers for Medicaid and Medicare Services (CMS), issued a mandatory, effective immediately, memorandum requiring all health care facilities to assess the risk of Legionella and Legionnaires’ disease within their buildings.

Each of these standards are applicable to specific groups. There is a need for incorporating requirements into code. ASHRAE put in a lot of effort to make sure that the language of the standard was code language. There have been propositions to incorporate ASHRAE standards into building and plumbing codes. I strongly believe that it is necessary. When we think back to one of the four Ds, denial, people prefer not to address this risk. Nevertheless, they will if they have too ­– especially if there is that ‘you must, you shall’ language, which is code language.

Doll: What is the likelihood of an outbreak today?

 Stout: Sadly, for a person who has devoted their entire career to the prevention of this disease, I have to tell you that outbreaks continue to occur. In fact, in recent publications from the CDC, they investigated and reported various sources of outbreaks. 44 percent were from hotels and resorts, 19 percent from long-term care or nursing homes, 15 percent from hospitals, and 21 percent from senior living facilities, workplaces and the community.

There are many opportunities for prevention. One of the statistics from those CDC investigations was extremely problematic, making hospitals a major focal point of my research. Over 50 percent of the cases in the outbreak investigations were from hospitals, which accounted for 85 percent of the deaths – a formula or target for prevention.

Doll: What advice do you have for controlling the growth and spread of Legionella? What can we do on a daily basis that will help prevent an outbreak?

 Stout: Test for Legionella. Detection is necessary in order to assess the risk in the building, so testing is the first step. Then, you must determine whether or not you’re in the 50 percent of buildings that have Legionella. If you’re in the 50 percent that do have Legionella, the question is, What kind of Legionella is present? Is that Legionella pneumophila serogroup 1, which is causing the infection? If so, you move to the next D, which is disinfection.

For the last 20 years, we’ve evaluated every approach to controlling Legionella in building water systems. There are ways to control it. One piece of advice for people that visit hotels is to turn faucets on and let them run at the highest temperature for at least 10 minutes. In addition, decorative fountains have been associated with Legionella, so consider sitting near a fountain for only 10 minutes.

Within the ASHRAE standard and in the CMS Memorandum are stipulations that water management or a water safety plan can help a building owner understand the system as well as recommended control measures to reduce the risk as an ongoing approach to prevention.

Legionnaires’ disease is not something that is solved after a plan is created. The plan is a roadmap to prevention and controlling the risk. We’re not trying to get to zero Legionella in a building because it’s virtually impossible to achieve as this is a naturally occurring bacteria. We are trying to achieve zero cases of Legionella, and if you control the organism, you can control the risk.

Doll:  For those of us that want to learn more about this topic, what books, articles or other resources do you recommend?

 Stout: Many years ago we started an informational website called There are frequently asked questions available for different groups including physicians, laypersons and infection prevention engineers. We also provide papers and articles from our group that contain information about the disease and disinfection. Another website is, which has a lot of educational information and presentations. Our mission at the Special Pathogens Lab is to end Legionnaires’ disease. As a laboratory, we provide ways to detect Legionella and to help develop water management plans. We also focus on educating because we firmly believe that people who understand this disease will want to help prevent it.

Doll: I will be checking out those resources. Now, for the final question – we ask all our guests this one! If you could choose a favorite building, maybe due to style of architecture, type of materials used, fun story, or connection you have to the building, what would it be and why?

 Dr.Stout: It’s actually two buildings by the same architect, Frank Lloyd Wright. I was raised by an artist, so I have a great appreciation for art museums. One of my bucket list items was to go to the Guggenheim Museum in New York City, which I finally did a few years ago. It has an incredible, whimsical, spiral design. Then, of course, in Pennsylvania there is the classic Falling Water with its cantilever design and really unique architectural features.