 Good morning, everyone. I'm Sarah Free from the news office here at the National Academies of Sciences, Engineering, and Medicine, and I'd like to thank you for joining us this morning for our webinar on our new report, Management of Legionella in Water Systems. For those of you not familiar with the U.S. National Academies of Sciences, Engineering, and Medicine, we are private nonprofit institutions that provide independent objective analysis and advice to the U.S. to solve complex problems and inform public policy decisions related to science, technology, and medicine. For each requested study, panel members are chosen for their expertise and experience and serve pro bono to carry out the study's statement of task. The reports that result from this study represent the consensus view of the committee and must undergo external peer review before they're released, as did this report. I have with me several members of the committee to discuss the report, but before I introduce them, I just want to go over a few logistics. We'll start off with a presentation summarizing the report by the committee members, and then we'll open it up to any questions you may have. And to ask a question, you'll see that at the bottom of your screen there's a Q&A icon, which you can click to submit a question. Also, if you need technical support during the webinar for some reason, please also use the Q&A button, and we will try to solve it. And now I'd like to introduce the members of the committee that wrote the report who are here with us today. First of all, Joan Rose, who's the committee chair, who is Homer Nowlin Endowed Chair of Water Research at Michigan State University in East Lansing. Ruth Berkelman, who is Rollins Professor Emerita in Epidemiology at Emory University in Atlanta. Michelle Priveau, who is Industrial Chair on Drinking Water at the National Science and Engineering Council of Canada in the Department of Civil Engineering at Polytechnic Montreal, and Amy Pruden, who is W. Thomas Rice Professor of Civil and Environmental Engineering at Virginia Tech in Blacksburg. And now I will turn things over to Dr. Rose, who will offer an overview of the report. Thank you very much, Sarah. And I'm very pleased to be here to present the overview of the committee's work. The report is a comprehensive examination of the state of science of Legionella, along with the recommendations, and I will briefly go over some of these. Well, Legionella arrived on the scene in a very dramatic fashion. In 1976, a very large outbreak of 182 cases and associated 92 deaths occurred in Philadelphia. Once it was investigated, the culprit was identified as Legionella nemophila. And today, this same bacterium causes 80 to 90% of the reported cases. There are two syndromes associated with the infection. Legionnaires' disease, a pneumonia-like disease with this high mortality rate, anywhere from 3 to 33%. And Pontiac fever. It's a less well-known, less well-studied syndrome. It causes mild upper respiratory infection. And it often goes undiagnosed. We recognize that there are many individuals in the community who are susceptible to this particular disease. The risk factors include age, gender, smoking, and immunosuppression. Other underlying factors, such as diabetes and other types of pulmonary disease. Legionellanosis is increasing in the United States. In fact, the incidence, the cases per 100,000 population, have increased from year 2000 up to 2017 by about five-fold. And 96% of these cases are sporadic. They're not associated with any known outbreak or any known source. And 70% are community-acquired. The CDC has estimated that drinking water disease costs about $970 million a year. Legionnaires' disease is about half of this. And it's about 10 times the traditional enteric waterborne diseases, such as Giardiasis and Cryptosporidiosis. Here you can see in this graphic on the bottom right the etiology of drinking water outbreaks in the U.S. from 1971 to 2014. And you'll notice this black bar increasing in particular in the last decade. Legionella contributes to approximately 50% or more of the documented waterborne outbreaks in the United States currently. Now, we know Legionella is transmitted through the inhalation of aerosols, which carry the bacteria into the respiratory system. There are many sources in our community that create these aerosols. In buildings and homes, there's showers and faucets. There's cooling towers. There's hot tubs and decorative fountains. We have learned quite a bit about the transmission of the disease through the investigation of various outbreaks. Here's just a few that have been documented. They all demonstrate very high numbers of cases and demonstrate this high mortality rate. The Dutch flower show in 1999 associated with whirlpools and spas. There's been several outbreaks associated with cooling towers, including in Australia, in Portugal, and then, of course, the one in 2015 in the Bronx in New York City. There have been outbreaks associated with wastewater treatment, aeration ponds, associated with water supply changes, such as in Flint, Michigan in 2014 and 2015. And in addition, contamination of premise plumbing, as was seen with the Quincy Illinois State Venture and Home Outbreak in 2016. So we can jump forward 40 years since the discovery of Legionella. And we have learned quite a bit about the bacteria's biology and ecology. We actually now have methods for monitoring both the disease and the concentration of the bacteria in water samples. However, as the previous slides have demonstrated, much less progress has been made in preventing Legionella's disease. It is not well understood how to reduce colonization of water systems through treatment. In 2017, the National Academies of Sciences, Engineering, and Medicine were asked to convene an expert committee, the Committee on Management of Legionella in Water Systems, to review the state of the science with respect to Legionella contamination of water systems and issue a report. The committee's work focused on five major themes. Ecology and diagnosis, the transmission of Legionella via water systems, quantification of the bacteria as well as the disease, prevention and control, and policy and training issues. There were a number of questions under each of these themes that guided the committee's work, included understanding the microbial ecology, improving diagnosis, understanding primary sources of exposure. What are the characteristics of water systems that make them likely to support the growth of Legionella? How do we quantify Legionella in water systems? And how do we quantify the disease? What are the most effective strategies for preventing and controlling Legionella? And what policies, regulations, codes, or guidelines are there to better protect the public? And how might these be improved? So I'd like to introduce the full committee to you. And starting on the right-hand side at the top is Laura Ellers, our study director. Without her experience, her expertise, and her guidance, I don't think we really would have been able to get this report accomplished. Next to Laura is Michelle Travol, Chuck Haas, John Lettson, Ruth Berkelman, Steve Pergam, Mark Lechevalier, Amy Prudin, Lonci Weeks, Paul Vendor Villin, myself, Paul Gutilies, Michelle Swanson. And Nick Ashbalt is superimposed here as he was on the conference call the day we had the photo. And Raymond Cipera, who was the senior program assistant, and kept us all on task. Now, as already mentioned, these committee members, these 13 committee members were chosen for their expertise. And we had broad expertise represented on the committee. We had expertise in clinical diagnosis, microbiology and microbial ecology, engineering, public health, water treatment. We had experience in cooling towers and experience in hospital water systems. There were three MDs, three individuals from Canada, and one individual from the Netherlands that made up this committee. We had six committee meetings to develop this consensus report document. And it was a pleasure, I can say, to work with all of these experts. So I'm going to go over briefly the chapters in the report and give some of the highlights around the recommendations. This will be followed as Sarah has said with a Q&A. So chapter one really covered much of what was known and some of the early documentation on disease and outbreaks. I've presented some of this in the previous slides. It's clear that water and the built environment are major ecological niches for these bacteria to grow. And this includes water sources, soil, drinking water treatment systems, cooling towers, as already mentioned, wastewater systems, and all the way through to the wastewater systems. In the past, the major focus was on biocides for cooling towers and for hospitals. Chapter two focused on the diagnosis, ecology, and exposure pathways. There are now 61 species officially described within the genus legionella. Legionella pneumophila is the most dominant species isolated from patients. And there's a number of reasons for this, and we'll touch on this in a few more slides. Legionella has these 61 species. It also has sero groups and sequence types. There are other pathogenic species besides legionella pneumophila. There's legionella macadatei, bosomani, dumafi, and longbitchie. So the genetics are quite complex, and the organism is very diverse. The ecology is also very complex, and this is now being revealed. The bacteria can exist in numerous forms. This includes the transmissive form with the flagella, includes the replicative form, mature infectious forms, as well as viable but non-culturable-like cells. These are cells that are viable, but they are very difficult to culture in media and isolate from environmental samples. The primary growth habitat of legionella pneumophila is now known to be within amoeba or other free-living protozoa that are associated with biofilms in pipe systems. There are various forms of packaged legionella that are released. These cell forms may be free-living. They may be intracellular, or they may be packaged in vesicles. And why this is important is because these cell forms and these forms that are released differ in their infectivity and their virulence, and they differ in their resistance to treatment, including temperature and disinfection. The committee had several conclusions and recommendations. Protocols should be developed to generate, identify, enumerate, and report distinct legionella cell types. There is an urgent need to understand whether legionella pneumophila and some of the other pathogenic species enter into this viable but non-culturable state, which is both resilient and could be reversible. Ecological studies should be focused on other legionella species. As we've already mentioned, there are 61 other species. There are other pathogenic species. And there has been a focus on legionella pneumophila. So the other species need to be studied. We need direct observations and metagenomic studies to really understand the full microbial diversity and the niches, the habitats, the relationship of the pathogenic legionella with their protozoa. There are a number of questions and data gaps that arose as chapter 2 was written. How does legionella cause paniac fever? The mechanism has not understood. What is the role of aspiration in terms of disease? And how does legionella and how well does legionella survive in the various types of aerosols produced? Chapter 3 focused on the quantification of legionella and legionnaires disease. It covers disease surveillance and estimation of the rate of disease in the US, environmental monitoring, and examined data from across the world, and also explored the use of quantitative microbial risk assessment for legionella pneumophila. There are evolving methods for the quantification of legionella. And there are current methods which are in use. They are used for a whole variety of purposes, including diagnosis, outbreak investigation, some for routine monitoring, mitigation, and research. The urinary antigen test is used most frequently for the detection of the disease. But it only detects legionella pneumophila serogroup 1. So the other pathogenic species are not identified with this commonly used test. There are standard culture methods. But new culture methods are evolving that may offer some advantages. There's also quantitative PCR and quantitative digital PCR. These primer sets can distinguish the genus, legionella pneumophila serogroup 1, anisea, macadatei, lung BTA, and bosbani. With full genome sequencing techniques available now, it's likely that other primer sets and more methods will evolve. And there are also methods to look at how you can isolate or better isolate legionella and the associated amoeba. So the diagnosis disease caused by other legionella species is very difficult. There needs to be an investment in the new methods, modified culture techniques, and molecular tools. These need evaluation. They will need training. The labs will need to have proficiency testing. And these methods should be used for national approaches for surveillance, ultimately, as they are compared and adopted. Currently, the committee estimates that there are between 52,000 and 70,000 cases of disease in the United States. This estimate is about eight, maybe approximately 10 times higher than the current reported disease incidence. And this underestimation is supported by data from a variety of other studies. The committee also evaluated legionella concentrations in waters from around the world. Many of the studies only presented a present absence and did not have quantitative information. And much of the data was difficult to interpret. However, there were a number of studies which had investigations that did provide concentrations. Using culture techniques in a whole variety of community-based settings. This included residential properties, hotels, wastewater systems, recreational venues like spas, cooling towers, and wastewater treatment plants. The committee found that around 50,000 colony-forming units, there seemed to be a break between the levels found in waters during outbreaks. That's those in these red and orange lines. And those concentrations found during routine sampling. That's seen in this graphic in these green lines. 50,000 CFU per liter should be considered an action level. That is a concentration high enough to warrant serious concern and trigger remediation. An alarm bell, so to speak. It's clearly recognized that for sensitive populations, a lower level may be necessary for these at-risk populations. Chapter 3 recommends the need to develop better clinical tools that will capture more cases of Legionnaires' disease and identify more species that are responsible for the disease, beyond Legionella nemophila serogroup1. In order to just determine the sporadic sources of disease, this will require a well-funded population-based study. Recall that I mentioned that 96% of the cases were sporadic. And this should be a study or a set of studies that is done in multiple jurisdictions across the United States. There is a recommendation that regional centers of excellence be established. These could serve as a backbone to strengthen the capacity of the state health laboratories. But these centers could also provide training and education, assist with water safety plans, and oversee these multi-jurisdictional studies. There needs to be a systematic comparison of the new methods, the current methods, and some of the new molecular tools that are emerging. Finally, quantitative microbial risk assessment is a second way to set numbers. The examples of these are in the report. And this framework is ready to determine concentrations that could be used to set standards and targets for routine monitoring and for determining effectiveness of cleanup and for regulations. Chapter four focused on the strategies for Legionella control and their application in building water systems. The main control strategies are addressed, their application to different buildings and devices are discussed. There are confounding influence factors which are mentioned, including green buildings, water, and energy conservation. Finally, there are recognition that there is future issues, things like probiotic controls, and other opportunistic pathogens that would need to be considered as strategies are implemented for Legionella control. This graphic on this slide shows the four main strategies for control, elevated temperature and plumbing materials, disinfection, and hydraulic design, as well as several other controls, nutrient limitation, aerosol control, and the design of the distal system. The committee was able to put a table demonstrating the multi-strategic approaches that are needed to control Legionella in a variety of water systems. The control strategy is here on the left. You can see the check mark is evident where these strategies have been successfully implemented and shown to decrease Legionella colonization. Each of these are described in the report. The question marks we see here in several cells and boxes here in the table. Where there's potential for these strategies to be used in these various systems, and these would require further investigation and documentation. You can see there's quite a few blanks under some of the systems for various strategies, and here there was no data which supported that these strategies were able to effectively work in decreasing Legionella colonization. And finally, you see the X's here under green buildings. This is where there was some evidence that the strategies were counterproductive in terms of the growth of Legionella. Chapter 4 recommends that for all building types, hot water heater temperature should be maintained above 60 degrees C, 140 degrees Fahrenheit. And the hot water temperature to the distal points, not to the fixtures, should exceed 55 degrees and 131 degrees Fahrenheit. Compared to free chlorine, monochloramine as a secondary residual, both in distribution systems and in building systems, controls Legionella is superior in controlling Legionella. However, the reasons for this are not yet clear, so the mechanisms are not understood. There's clearly research needed to understand how the disinfectant works, how it persists through the distribution system and within the building plumbing. There's guidance that's needed for homeowners, in particular, about Legionella and especially consumers from at-risk segments of the population. Low fixtures should not be allowed in hospitals and long-term care facilities because of these buildings' high-risk occupant populations. New designs are needed to help advance the control of Legionella in cooling towers and humidifiers, particularly use of temperature control in cooling towers. Green buildings and other types of water and energy conservation may have worsened the problems with Legionella and this should be investigated. Chapter 4 summarizes the scientific data that supports both the strategies and the evidence. Chapter 5 focuses on regulations, guidelines for the control of Legionella in water systems. It should be noted that the safe drinking water act does not provide protection from Legionella. The role of the water utility today is really focused on delivering water with a disinfectant residual to the service connection, but what happens is the water moves into the building as uncertain. There are a number of differences between premise plumbing and main distribution system. This includes the length of the pipe, the surface to volume ratio, and water age. And these are all differences that can promote a difference in Legionella colonization and growth. Currently, there's no evidence that residuals persist within buildings. Currently, there's only a few regulations in the US that focus on the management of Legionella. These regulations may require water management plans and or monitoring. Now, water management plans capture what controls will be used in a building for a device type to prevent the growth of Legionella. One must establish a program team. This should be a multidisciplinary team. The water system should be described. The hazards should be analyzed. Where is it that Legionella can grow and propagate? And where are the exposure sites? There should be an identification of control measures and where these control measures should be applied. Certain parameters, including, in some cases, Legionella should be monitored. And there should be a determination if these control measures are working. There should be confirmation that the program has been implemented as designed and that the program effectively controls the hazards. This all has to be documented from the plan to the analyses. So as mentioned, there's only these current regulations, both in health care facilities in New York State, cooling towers in New York City, and the state and health care facilities within the VA system, which require water management plans and monitoring. Hospitals and health care facilities, receiving Medicare and Medicaid funds, currently only require water management plans. Now, there is a voluntary creation or guidance around the creation of water management plans for buildings. But at this time, it is currently voluntary. All other building and private residents may be potentially protected only through the application of building and plumbing codes, which the committee found to be inadequate. The committee evaluated selected international Legionella regulations from six countries in the province of Quebec. Many of these countries did develop regulations that addressed a number of water systems and building types and devices, cooling towers, wastewater treatment plans, recreational waters. Temperature was a consistent approach in terms of control. They did require monitoring in these regulations. And they did develop thresholds. Many of these thresholds, you can see here, are quite low. And some are higher than the action target that the committee found when evaluating concentrations in water systems. We should mention that none of these numbers, these monitoring numbers, have come from a quantitative risk assessment. Germany, Canada, and Quebec all have evidence of lower environmental concentrations since the regulations went into effect. The recommendations in Chapter 3 really focus on what's already there and adding to those guidelines to enhance the effectiveness nationwide for the control of the disease. First, expand the Centers for Medicare and Medicaid Services memorandum to require monitoring for Legionella in environmental water samples for all hospitals. Second, register and monitor in cooling towers. This is already done in key areas, as already mentioned in New York, and in key communities such as Garland, Texas. Require water management plans in all public buildings, including hotels, businesses, schools, apartments, and government buildings. There are ways that may perhaps insurance plans could be involved in this. Require temperature of 60 degrees, as already mentioned, at hot water heaters and 55 degrees to the distal points. That is at the point of connection to fixtures, including thermal mixing valves where required to prevent scalding, and require a minimum disinfectant residual throughout the public water system. In order to implement these recommendations, there's also other approaches needed. Guidance is needed on interpretation of monitoring results, including the setting of start targets, as described with QMRA in Chapter 3. The table to the right gives some examples of some critical concentrations found through the QMRA process. There's going to be a need for training and education as more water safety, water management plans, and more monitoring comes into play. And there is a need for a better cost estimate of the implementation as these recommendations may roll out, and the timing that these recommendations should be implemented. Finally, we should say that many different entities are going to be needed to address this problem. What is the role of testing labs currently, of federal agencies, of public health labs, researchers, insurance companies? So this will require a shared responsibility, and many players will have to be involved to implement the recommendations in this report. Many of you in attendance likely fall into some of these categories, and it will be all of our responsibilities to move forward with a national approach to decrease Legionnaires' disease, and in particular protect our sensitive populations in the future. Thank you for attending this webinar. We will now go to questions, and you are able to access and download the report for free at this website, www.nap.edu forward slash catalog forward slash 25474. Thanks, Dr. Rose. This is Sarah again. I just want to remind you all, if you have a question, please use the Q&A button at the bottom of the screen to submit it. We have one question from Khalid Mumanis, who asks, from which reference did you get the data about Quebec's critical concentration? Does one of the committee members want to answer that? Yes, I think Michel Provo can probably answer that specifically. Yes, thank you, John, for that question. The data, I'm not sure I'm getting the question clearly, the data about the critical concentration actually the data presented for the Quebec monitoring of cooling towers is data shared, as mentioned in the report, by RBQ and SQI, two organizations that allowed the sharing of their data of monitoring of cooling towers. They were not used to the best of my knowledge and to the in formulating the estimates for critical concentrations that Dr. Rose presented earlier. Thank you. Our next question is from Joseph Cotruvo, who asks, the Safe Drinking Water Act does not extend to private property. EPA's interpretation of consecutive systems would cause a building that wanted to install supplemental treatment to become a public water system. Did you suggest ways that supplemental treatment could be facilitated within the current SCWA, such as exempting hot water plumbing sites? Yes, the committee did have some discussion on this. And Amy, I believe there was discussion in Chapter 4 and on strategies and the role of water utilities. And maybe you are able to provide insight into that question. Sure, thank you, Joe, for bringing that issue up. For sure, the role of the Safe Drinking Water Act was central to the committee's consideration of options for controlling Legionella and on our minds in preparing this report. In Chapter 4 on the engineering controls, we took a scientific perspective focusing on what we know from the science works. And so we do know that adding some form of disinfection, typically to the hot water lines, often chloramines, that is something that's scientifically been demonstrated to reduce numbers of Legionella and is associated with reduction in disease transmission. So that's the science. And you're absolutely right that the Safe Drinking Water Act, at the time that it was crafted, there was not this awareness of the difference between Legionella and what we had dealt with in the past with the fecal pathogens. So fecal organisms, things like typhoid, Safe Drinking Water Act does a great job at addressing those in terms of filtration and disinfection. But the Safe Drinking Water Act only goes to the property line. And as we discuss in the report, it's within buildings, the inner pipe surfaces and fixtures. That's where Legionella resides and grows in biofilms. And so the Safe Drinking Water Act requirements do not directly address issues with Legionella. And further, if building owners do want to follow the science and include some sort of on-site disinfection, according to most interpretation of the Safe Drinking Water Act, and it does vary state to state and locality, that's in conflict because that building then becomes a public water system. So this is discussed in the report. But at this point, I think we bring that conflict to light. And if there's ways that in Congress that can be dealt with, that would be wonderful. In the meantime, there is research that's been recommended in how public systems can better monitor their water supplies and what can be done at the water supply level, as well as at the building level. But you're absolutely right that we need for our public policy to be in line with the practices that we know control Legionella. Thank you. We have a question from Victoria Griffin that I'm wondering if Dr. Berkelman wants to answer. Her question is, nursing homes are caring for high-risk residents with trachs, ventilators, et cetera. Why wasn't testing recommended for nursing homes? MIMO covers health care facilities. Certainly long-term care facilities are carrying the same risk of Legionella as high for their patients as they are in hospitals. So I would take a good look at the CMS MIMO, but I believe that that does cover long-term care facilities. If not, it's something CMS may really want to look at. Thank you. This question, I think, also for Dr. Berkelman. The most recent New York Legionnaires Disease Surveillance Report indicated increased incidence rates of Legionnaires Disease among those with high poverty levels and African-American Black race ethnicity. Are there specific recommendations or targeted interventions to address these disparities from a social determinants of health perspective? The question, it's important. We are seeing a higher risk. And those with lower socioeconomic status. And more research is needed to look at that. We did not make specific recommendations in the report regarding that, except to say more research really is needed in the area. There are a number of hypotheses around this. And they need to be explored, whether it's cooling towers in industrial areas or other things. Thank you. OK, thank you. We have a question. A listener wants to know what the acronym D-A-L-Y stands for and what it means. Dr. Rose, do you want to explain that? Oh, the dolly. Yes. So the dolly is disability-adjusted years loss. It is a metric that is used in the health profession to look at the burden of disease from various types of disease. It means that you could compare legionnaires with tuberculosis or with smoking. And in fact, the report does show that legionnaires disease has a very high health burden for both individual risks as well as population risks. So it's up there with more serious illnesses. OK, thank you. We have a question from Birgitta Bedford, who asks. And I think this question, Dr. Prevo, you might want to answer. You mentioned maintaining hot water temperatures at greater than 55 degrees Celsius at outlets. It's difficult to consistently maintain such high temperatures 24-7. Isn't this therefore dangerous to recommend? In my opinion, this could be energy wasting in places in undue burden on a state's department. It also could contribute to more contamination. What are your thoughts on this? Thank you for the question. Yes, absolutely. And the document chapter four reviews the evidence showing that temperature control across the system, as you mentioned, which is a challenge, can be achieved. All right, I'm intervening in the hospital or the large building hot water system. In the case of the issue of recommending these high temperatures versus the trade-offs with scalding, the committee carefully evaluated these trade-offs between the risk of scalding and the risk to be exposed to Legionella at the point of use. And from several large studies, some using tens of thousands of data points, we showed that high temperature were most effective. And as you said, especially when efforts were made to ensure that these temperatures were maintained across the premise plumbing or the internal systems of these buildings. OK, thank you. We have a question from Nikhil Sheff, who I think for Dr. Rose. You stated monocluoramine controls Legionella better compared to chlorine. Is that comment for use in primary disinfection or did research include supplemental disinfection use? Yes, this was research that focused on the chloramines as a secondary disinfectant, so use in the distribution system and use in the building itself. In both cases, this showed that it more effectively controlled the growth of Legionella. And I don't know, Amy, if you want to add any more to that, but the focus was on secondary disinfection and not primary disinfection at the water plant. Right, that's correct. The report cites field studies where the secondary disinfectant residual was switched to chloramines and numbers of Legionella decreasing and also at the building scale when chloramine disinfection units are installed. And we bring to light that scientifically it's not known exactly why chloramine has these advantages and it would be useful to know in terms of optimizing its use and application. OK, thank you. We have a question from Craig Boyce, I think, for Dr. Berkelman or Dr. Prevo. There's a conflict between scalding and Legionella control due to recommended temperature setting. Is there any data to support and compare the severity of each risk? Legionella deaths versus scalding deaths, et cetera. So, Michelle, you're still on mute. There we go. OK, so yes, this tradeoff between scalding and the control of Legionella was discussed abundantly within the committee. And as I mentioned previously, we looked at abundant data showing that the benefits of elevated temperatures to control Legionella in all kinds of large buildings. And more importantly, we came across documented evidence that when you actually went away from temperature control to conserve energy, several of the problems came back and temperatures had to be increased again. Now, this being said, obviously, scalding prevention is a primary objective, and this scalding risk is especially important for vulnerable populations. But it can be addressed by installing thermal mixing valves at when justified at points where, for example, showers or bathtubs where the risk is most acute. And these TMVs have been used widely in the US and Canada across Europe. And they are actually already prescribed in some of the regulations plumbing codes and guidance. So I believe there's a solution for this risk. And the tradeoff to minimize Legionella is what the science told us was the best approach. Thank you. We have a question from Charles Maddox that Dr. Rose, you may want to speak to this. The Safe Drinking Water Act surface water treatment rule assumes Legionella is controlled if Giardia and virus treatment requirements are met. What is the committee opinion of this? Well, we believe the Safe Drinking Water Act as currently written and the surface water treatment rule, which had been developed to address microbes, does not control Legionella. It does talk about a disinfectant residual. And as already mentioned, the monitoring of the residual and the assurance that the residual is entering the building really ends at the connection, at the service connection. So the recommendation is to better ensure residuals are entering the building and the building premise plumbing. We do think the water utility has a role to play in examining both the research needs on the type of disinfectant and the mechanisms as well as how one might deliver and monitor these residuals as they move into the building. Thank you. We have a question from Craig Boyce. And Dr. Prevo, you might want to speak to this. Was cold water considered in the research? Because this is also a concern. Yes, absolutely. Cold water was considered. And in chapter four, there is abundant information about the presence of Legionella in distribution systems, for example. And if you look at the data from several European countries, some Canadian data and some recent American data from one of the committee's member, Dr. Lechivalier, you see that these numbers in the distribution system range from 3% to 7%. So Legionella is there. It is present in surface water and soil in the environment in general. It is present in water. Now where the committee could not find really practical solutions to recommend is how to keep cold water colder, how to make cold water colder to keep as cold as possible to minimize the risk within building systems. It is recognized that below 25 degrees C, the risk is lower. So yes, we did look at it. The risk appears to be lower than hot water. But it could be a significant in the case of utilities with very warm climates. If I could add to that. So for sure we talk about keeping cold water cold to the extent possible, hot water hot, avoiding the growth range of Legionella. But we talk about the complexity of the control factors. So you have temperature as an overarching control. You have disinfectant as a barrier. You have your hydraulic regime and making sure that temperature and disinfectant is reaching your distal locations. So it's complex. It's interactive. So if you're in a situation in a warm climate, you know your building is vulnerable to warm water, then it becomes especially important to look at these other controls and consider adding disinfectant and watching your hydraulics. Thank you. We have a question from Brad Considine that Dr. Rose, you may want to speak to. He asks about your data on Legionella bacteria counts used in the report. Is it all cultured live bacteria data? Or does it include tests that identify both live and dead bacteria? So chapter three does summarize the studies that used PCR, quantitative PCR methods. However, the figure that was produced on the 50,000 colony forming units per liter, that all came from studies which were using similar culture-based methods. But quantitative PCR data was summarized in the report. And that would include both live and dead bacteria. OK, thanks. We have a question from David Schultz who asked, I'm not sure which committee member wants to speak to this, what are new laws or regulations needed most urgently right now in the US, the federal, state, or local level? Well, I'd say that the committee's recommendations were that this would be multiple entities would need to come together. And that may mean new committees or new approaches are developed so that you have these different layers. Because we do believe that to control Legionella ultimately, you will need both the federal, state, and the local individuals to be involved. Amy, I don't know whether you would like to add a bit to that. Right, I agree. Towards the end of your presentation, you emphasized the multi-stakeholder approach. So everybody from consultants to labs to local government, federal government, researchers, everybody has a role to play here. Now when you get into recommending regulations, again, as I spoke to with the Safe Drinking Water Act, that's a whole other challenge getting lawmakers involved. But I think we identified an opportunity with the CMS memo is one opportunity that we could require Legionella monitoring along with water safety plans. And I think a take-home message across the board was we need to require water safety plans for all public buildings, so not just the VA hospitals or hospitals covered by Medicaid and Medicare, but schools, hotels. Any kind of public building would benefit from having a water safety plan. And how that gets implemented and put in place, I think, involves all stakeholders. Michelle? Thank you. Have a comment. Yes, to add to what Amy just said, the committee also recommended to register and monitor cooling towers because there's evidence to show that once they are monitored, then registered that the actual concentrations in these towers decreases. And the number of towers at risk of causing outbreaks is much lower. The second reason behind that and why it was put forward is that it does help to investigate whenever there's a cluster or an outbreak. So such regulations was put forward because of these two reasons, really. OK, thank you. We have two questions from Anne Sealy on that Dr. Berkelman you may want to speak to. First of all, regarding the increase seen in Legionella incidents over time, do you have any comment on the extent to which this increase is likely a factor of greater awareness, more testing, better methods, versus an actual increase in incidents? Great question. And why is Legionnaires' disease increasing? Why are we getting more reported cases? We have a more vulnerable population in the United States today than we've had. We have more elderly. They are at increased risk. We have more people who are immunocompromised who are also at increased risk. On the flip side, we also have environmental factors that are contributing to the increase. We have an aging water infrastructure. We have water main breaks. We have corrosion in our pipes. We have more complex and more water features than we've had in the past. We also have more water conservation. And water conservation actually may decrease the flow and cause more stagnation. And also, we may have lowering of the temperature to increase efficiency. And that may contribute to more Legionnaires' disease. We also have global warming. And we have associated Legionnaires' disease with periods of heavy rainfall, which we have more of, and also increasing temperatures. The cold water in many of our states is getting warmer and above that 25 degrees that Michelle was talking about. So I think we have a lot of reasons to say we've got to treat this curiously and as an increase in awareness. OK, thank you. And a second question. Because an important public health goal seems to be to reduce severe illness and death, do you think it's important to focus on increasing awareness of public and health care providers to improve testing and medical treatment of patients? The answer from our committee would be yes, that health care professionals need to have more awareness of this disease and use available tests for the disease. And we do have tests now. And they are not used often. Instead, patients who come into hospitals, even the patient hospitalized with pneumonia, are not always getting tested for this disease. And one cannot tell the difference clinically between a patient with another cause of pneumonia and one with a degenerative disease without clinical diagnosis. And we know the majority of the patients that are hospitalized with pneumonia are not being tested today. Thank you. We have a question from Zoe Goodson that Dr. Pruden, you may want to speak to. Was copper silver ionization as a control technology evaluated? Was there any evidence that copper silver is an effective technology? Also a very good question. And yes, chapter four of the report goes into detail of several disinfectants, starting with chlorine, chloramine, chlorine dioxide, copper silver, as well as UV and others. And there's not a lot of information on copper silver. There are some studies and some that show that it can be beneficial. There's others that show that it doesn't work. And I think from what we saw of the literature, it's very situation dependent. So for it to work and for the antimicrobial copper and silver to be delivered to the Legionella cells and to kill them, you need to be aware of things like the water chemistry to make sure that they don't just precipitate out of solution or plate onto the pipes. And so I think it's an area of research that would be worthwhile to understand how to optimize copper silver for specific applications. Thank you. We have a question from Darren Klein that Dr. Rose, you may want to speak to. You recommended minimum levels of disinfectant in the water distribution system. What level do you recommend? Well, there wasn't a very specific number, although measurements at 0.1 are most reliable in terms of measuring out in the building systems. But again, this is where the recommendation on research was clear, because we don't have a lot of information on delivering disinfectant residuals to the fixtures and through the premise plumbing in the building. If I can add to that, so I think we've seen associations where if disinfectant residual is low, within the distribution system, then that can create vulnerabilities. So for example, in Flint, Michigan, because of the corrosive water, iron was released into the water that reacts with chlorine. So it was very, very low, so that might be one extreme. But work is needed to see if there is some target disinfectant level that enters the building. And work is also needed to understand once it enters the building, because for the most part, it's assumed that even if you have half a milligram per liter chlorine or even one milligram per liter, that the complexities in the building, the surface area, the temperature, are really going to lead to further decay and loss of that residual. Thank you. I'm going to. Oh. I didn't know if Michelle wanted to add to that. I may. And to add to what Amy just said, whatever the control measure you have going into a building, if the water stagnates, is not circulated throughout the building, then neither temperature or residual will get to these distal parts, to these different parts of the system. So the committee in Chapter 4 really talked about the hydraulics that we refer to. That is so important to address so that whatever control measure you have in place, it gets to every point in your building. Thank you. We have a question from Allison Chamberlain that Dr. Berkelman may want to speak to. In light of recent hotel-related outbreaks, should hotels be encouraged to include legionella bacterial counts as part of their WMP verification protocols of potable and non-potable water systems? One that the committee did grapple with, we went to health care facilities and for cooling towers. So that would apply to hotel cooling towers. We also said, let's focus on the water management plan and suggested a number of guidelines and hotels. We did not make a recommendation regarding monitoring of hotels and other public buildings at this time, other than hotels, but certainly to be considered. And Joan, you may want to add to that. Yeah, I think within the water management plans, there are approaches, especially during validation and verification stages, where larger hotels may want to do monitoring. And then it may not need routine monitoring, but may need monitoring as the water management plans are implemented. And so that was discussed. But the committee did not recommend routine monitoring in hotels at this stage. Just one follow-up. We also did not discourage it. Right. OK, thank you. We have a question from Jason Del Camp that Dr. Prudin, you may want to speak to. Have any studies been conducted to show if there's a difference of concentrations when using plastic piping as opposed to copper? Perhaps Amy, you would like to answer this one because you wrote this section on materials. How about I give it a shot and you fill in the blanks? So that is a very good question. And we do have a section on pipe materials, or materials in general, and their potential as a control. And I think what we saw in general is it was a bit lower on the hierarchy. We saw temperature and disinfectant and hydraulics as really dominating control measures, whereas pipe material is a secondary measure. And part of the issue is that they can be reactive. So for example, copper, we know that when it's dissolved and in solution, copper 2-ion can kill Legionella, right? Well, a copper pipe is zero-valent copper and it can corrode, which actually might be a good thing because it's releasing copper. But it can also get a layer that's blocking the release of copper ion. Now, plastic materials such as packs and other popular materials that have many benefits. One of the challenges is that they do tend to be a bit more vulnerable to microbial growth in many circumstances. So for example, they can leach organic carbon into the water. There have been studies of shower hoses in particular that certain types of plastics are more vulnerable to bacterial growth. But what was interesting and what we saw was it wasn't necessarily Legionella growing. And so that brings to light important work to be done just to understand the basic microbiology of premise plumbing systems and that not all bacteria are necessarily bad. You will have bacteria in your premise plumbing. And so I think there's work to be done on understanding how these materials foster different kinds of microbial communities and whether those encourage Legionella growth or not. Michelle, you want to jump in with that? No, I think you summarized it well. The challenges with the shower hoses is perhaps one of the most interesting bits in the report for all to read how important these materials at the point where you're probably the most exposed in the household, how important these materials are. OK, thank you. We have a question from John Lee that Dr. Rose, you may want to speak to this. And he writes, I have one question regarding action levels. I suspect what you really mean by this is that it's a level at which there is a real risk of infection occurring. What's more important, really, is that what level people should be reviewing their controls and maybe taking action. Your last slide is approaching this, I believe. I would suggest that it's too late when the level has already reached the action level you have identified. Yeah, so the committee really purchased values. One was based on monitoring data. And that is an alarm bill. That level that was presented as the action level is the alarm bill, an alarm bill going off. This is for community monitoring, community water systems, say, fountains and other things that people may monitor or may not monitor routinely, and then they get these high levels. The committee believes that those data weren't immediate concern, that they're reaching a level where you could have an outbreak. They're above where we might just see sporadic cases. Now, the second approach that looked at what kind of numbers might guide targets or remediation and routine monitoring information is using the QMRA approach. And in that case, the numbers are much lower. They're risk-based, and they're focused on probability of infection. So these were two separate approaches. One, based on what we know about current monitoring and a number in which, if you reach that, an alarm bill should go off and immediate action should occur. And then the second approach, which focused on using a QMRA framework. OK. Thank you. We have a question from Jessica Fullerton that Dr. Prudin, you may wish to speak to. She asks, there are challenges in older buildings with aging-forming infrastructure when it comes to superheating and hyperchlorination. Do you know if monochloramine is gentler on the system than other typical disinfection methods? That is a pretty good question. And I can say, I don't recall that the report direct address that directly. Michelle may have something to add. Yeah, there's limited information available, but some in the couple of documented studies on the implementation of chloramines and other solutions like chlorine dioxide and copper silver and the impact in chlorination with chlorine. And the conclusion is that it is, as compared to high temperature, easier in terms of potential damage to the old plumbing in older buildings. That is why Amy mentioned a bit earlier that there's quite a bit of evidence that chloramines coming from the distribution system or chloramine from a treatment unit at the entry of a large building has the potential to control Legionella. Now, is that enough without high temperature? That still remains to be seen. And there's evidence to the contrary that is available at this time. And related to that question, this is a huge issue that older buildings often have iron pipe. And iron pipe is addressed in detail in the report. It's problematic for many reasons, but it tends to be highly reactive. And it can be a sink for disinfectant, especially old corroding iron pipes. So there are cases discussed in the report where, for example, a hospital campus seeks to boost the disinfectant levels. And they're adding very high levels, but it's reacting with corroded iron pipes. So that's definitely a challenge as well. Thank you. We have a question from Rebecca Fugit that Dr. Rose, you may want to speak to. Many public water systems use above-ground storage of water to provide pressurization in their distribution system. Was this an aspect of public water system distribution considered with regard to Legionella risk? So the committee did have some data on occurrence where the investigations had looked at these storage tanks. And there was evidence of Legionella being able to replicate and accumulate in the sediments of these storage tanks. And that's potentially adding more Legionella into the system towards the buildings. And I'm not sure that beyond disinfection and hydraulics, the report in chapter 4 went beyond looking at these particular structures, these storage tanks. But there's data in chapter 3 on the occurrence. So they are a source. And then Michelle, in chapter 4, with the storage tanks further considered beyond hydraulics and disinfectant residual. No, I guess there's already quite a bit of guidance out there for utilities to use to clean their reservoirs. So when the various studies, Dr. Rose was referring to, showed that Legionella and their host were present in these sediments, it only strengthens the need to actually proceed to this periodical cleaning of the reservoirs to avoid the presence of these undesirable organisms in those reservoirs. Thanks, we have a question from Marcy Savage that Dr. Berkelman you may want to answer. With the announcement that 96% of Legionella's disease cases are single sporadic cases, can you speak to what is being recommended both to better understand the majority of cases and identify solutions to prevent them? Great question, and it's one that the committee spent a lot of time on and made recommendations in terms of the research to understand these cases. Right now, there's little capacity in the state health departments to investigate most of these cases for an environmental source, and we are recommending some very targeted population-based studies to really investigate sporadic cases. We don't know right now whether we can extrapolate from what we find in terms of an environmental source during the outbreaks to these sporadic cases. It's going to be very important that we get at this. Joan, do you want to add something? No, I think that the recommendation for both the Centers of Excellence and the multi-jurisdictional studies really kind of focused on the ability to handle more of these individual cases and better investigation and better tools where you could investigate. The sources of the aerosols and the contaminated aerosols. Thanks, we have a question from Russell Higbee. Dr. Rose, you may want to speak to this. He asks, I hope this report will help states and municipalities revise their control measures. Do you see this report as being their impetus to change their regulations? Well, we certainly see the state as a major player. That needs to be involved as these recommendations are implemented. And we talked quite a bit that these were part of the stakeholders that we felt the report would be of interest to. I'd say there are examples where some states and even local communities have already taken approaches. Garland, Texas was brought up and other examples where both the local community as well as the state moved forward. And so there are some examples which can be built upon by other states to address their problem, particularly those that are having concerns about the rising cases of disease as well as outbreaks. Ruth, would you like to add a bit more to that? You said it well. I just want to add that we did not take the tack of making explicit recommendations all the time, making them all mandatory. We chose some that we thought were very important, like cooling towers and health care facilities. But the report encourages much more action, including. And the states are often at the forefront of this. So they will need to look at this. And they are major stakeholders. But we're encouraging this direction. I think it's the best way I would put it from the report standpoint. Thank you. We have a question from Mary and Heyman that Dr. Rose, you may wish to speak to. Given what we know about increasing water temperatures in buildings for Legionnaires disease control, what can we as a group do to change national plumbing codes that would require a minimum of 140 degrees at specific points in the system, such as hot water storage tanks, and 130 degrees in order in distribution lines? If national codes are changed, states will typically adopt them. Yes. And the process for proposing changes and putting forward language was described to us. We do believe that the best science that can move into that process and into these committees that are involved. And I think even in that case, probably the recognition that multidisciplinary players should be involved as these are discussed, as the science is discussed and the language for change is moved in through the committee process. And maybe I don't know whether anyone else, one of the other panelists, would like to add to that comment. If not, we'll move on to the next question, which is from Paul Knechtius, who asks, and Dr. Prevo, you may want to speak to this. Did you find any data or information on the effectiveness of various inline or tapped filters for removing Legionella? Yes, we did. Actually, in the report, there's a section on distal points, which include in distal control. So point of use devices are discussed. And to summarize findings, they can be extremely efficient. But the issue of cost and clogging do come up depending on the water quality present in the building where they are used. OK, thanks. We have a question from Brad Considine. And again, Dr. Prevo, you may want to speak to this. Are there any examples where cooling tower regulations have reduced the rates of Legionnaires' disease in the jurisdiction? This is an excellent question. As Joan mentioned, 96% of cases are sporadic, and then 70% are community acquired. So at this point, although we have evidence of elevated Legionella in several cooling towers without an ongoing outbreak, we do not know if these concentrations cause sporadic cases. I think the only solution to really understand the relative contribution of these sources is to conduct the studies that Dr. Rose was referring to, which are studies that would identify the sources of these sporadic cases, which are the vast majority of cases. And the committee did look into whether there was evidence. Many of the regulations were relatively recent. And the committee looked into whether there was evidence that the regulations decreased disease. Thus far, we couldn't find that evidence. But they could find evidence that it decreased the concentrations of Legionella in the system. And I think that as time goes on, and as these regulations are in place longer, it will be important to try to develop that evidence, which is why the committee made some of the recommendations they did. Thank you. We have a question from Randy Earth-Pamer, and Dr. Pruden, you may wish to answer this. And he asked, does monocloramine or chloramines present any type of risk to human health for use as a secondary disinfectant? Well, I can say there's literature on that. But that's not something that we directly addressed in the report. I can say that within the US, they're used, they're required. And so yeah, I'd just say the report doesn't directly address that. Yeah, the committee did look at unintended consequences in some case, but it wasn't fully discussed. And so there's acknowledgment that there are in a number of places that there's a risk balance that needs to be addressed. But the committee did not focus on that issue. I would say that disinfectant byproducts are mentioned in terms of as it's being evaluated, whether to boost disinfectant levels that tradeoff is something that should be looked at. And yeah. OK, thank you. I think we have time for one more question. And we'll take a question from Carl Zebar, who asks. And Dr. Pruden, you may wish to speak to this. As Legionella increases in resistance to treatment modalities provided in the present, such as monochloramine, superheating, et cetera, is there any guidance on how to use multiple treatment modalities? Is there any research that exists demonstrating the effectiveness of multiple treatment modalities and is replacing piping the only resort once colonized? OK, that's a good question. So in terms of resistance of Legionella increasing to disinfectants, I am actually personally not aware of studies on that. I can say, as Dr. Rose covered, there are multiple species of Legionella, multiple strains, serogroups. And that, for sure, the strains of Legionella and their vulnerability to disinfectants does vary. And so it's plausible that certain situations could select for more tolerant or resistant forms. But again, I haven't seen that rigorously evaluated in the literature. I would say that this question, again, highlights the need for multiple barriers. So in developing a water safety plan, you wouldn't want to only rely on disinfectant, for sure. Only temperature, you want multiple barriers in place. Yes, and I think Chapter 2 very well describes this diverse ecology and different forms and how little we know about some of the other pathogenic Legionella and their forms and as they may be more resistant to our strategy. So this multiple strategic approach, depending on the building type or device or system, needs to be examined and included in the water management plans. OK, thank you. Unfortunately, it looks like that's all the time we have for questions today. So I'd like to thank very much our speakers for answering all these questions. I'd like to thank all of you for participating and for sending in so many good questions. And just a reminder that you can download a copy of the report and other supporting materials at the URL shown on the last slide. And again, thanks for attending. Bye-bye.