It seems like nearly daily we hear reports of new public health crises. One of the top public health risks is a Legionella outbreak at a hospital, hotel, long-term care facility or similar type of building. It is critical to understand Legionella outbreaks are not isolated incidences but reflect predictable patterns of failure in building water system management. In nearly all cases the outbreak could have been prevented had a properly implemented water management plan been in place.

The origin story

The first documented Legionella outbreak was at the 1976 American Legion convention in Philadelphia, Pennsylvania, when 221 people attending fell ill and 34 died. Since then public health agencies have improved their surveillance and understanding of how people contract the disease. Legionella is a global public health concern, and the number of cases is rapidly on the rise.

“In Europe, Australia and the United States, there are about 10-15 cases detected per million population per year.”
- The World Health Organization (WHO)

A WHO Legionella fact sheet points out that the true rate of incidence worldwide is not known because many countries lack adequate diagnosis methods and surveillance systems. However, a U.S. Centers for Disease Control and Prevention (CDC) Legionella fact sheet says Legionnaires’ disease is likely underdiagnosed. In the United States, the CDC reports that nearly 7,500 cases of Legionnaires’ disease cases were documented in 2017, a nearly five-and-a-half-fold increase since 2000.

Understanding risk

The bacterium that causes Legionnaires’ disease is found in the environment and only poses a danger to public health when it proliferates in the warm water found in building water systems. It is then spread through aerosolized water droplets and inhaled as mist.

These mists are created by cooling towers, decorative fountains, hot tubs, shower heads and other sources. Inhaled, the contaminated mist can result in Legionnaires’ disease, a serious lung infection that causes pneumonia. Symptoms include cough, shortness of breath, high fever, muscle pains and headaches.

The elderly and those with suppressed immune systems are particularly at risk, and about 10 percent of people who get this infection will die, according to the CDC’s June 2016 Vitalsigns report. In a health care setting, 25 percent of those infected will die, according to the CDC’s June 2017 Vitalsigns report. No other waterborne illness in industrialized countries is associated with such a high rate of death.

Cooling tower outbreaks

Cooling towers in building water HVAC systems generate the most risk and greatest potential liability. Roughly 60 percent of outbreak-related fatalities are attributed to cooling towers, according to a 2018 study, “Outbreaks of Legionnaires’ Disease and Pontiac Fever 2006-2017,” published in the journal Current Environmental Health Reports.

Consider the following examples of large-scale outbreaks associated with cooling towers since 2000:

  • 2001, Murcia, Spain – more than 800 suspected or confirmed cases, 6 deaths

  • 2005, Toronto, Canada – 135 confirmed cases, 23 deaths

  • 2012, Edinburgh, Scotland – 92 suspected or confirmed cases, 3 deaths

  • 2014, Lisbon, Portugal – 377 confirmed cases, 14 deaths

  • 2015, New York City – 138 confirmed cases, 16 deaths

Cooling towers operate on the principal that water evaporation extracts heat from coils containing circulating water. Evaporation volatilizes the water droplets carrying Legionella bacteria and spreads the bacteria into the air as an inhalable aerosol.

Illnesses from Legionella have been documented as occurring even a mile away from the contamination source, according to a WHO Legionella fact sheet. Often located in dense urban areas, cooling towers provide a mechanism for widespread human exposure if Legionella risks are not controlled.

While there is no question that risks from cooling towers can be effectively managed, inconsistent management practices continue to be observed. These practices are largely driven by facility managers not requiring water treatment firms to manage their cooling tower systems in accordance with best practices. To help address inconsistent management practices, FMs should use detailed protocols to establish clear risk management expectations from the water treatment firms operating their cooling tower systems.

Poor maintenance of cooling towers is one of the biggest challenges for public health officials and building safety agencies. This is due to the absence of a unified, publicly accessible registry for cooling towers. A public registry of cooling towers could help health investigators pinpoint the source of an outbreak as they look for commonalities among those infected with Legionella. It could also be a tool to develop strategies to monitor management practices at the building level.

By incorporating routine maintenance and management information into the registration system, building owners and public health agencies can respond to risk prior to outbreaks. In North America, the State of New York, New York City, the Province of Quebec and the cities of Vancouver, Hamilton and Austin have each established cooling tower registration or maintenance requirements. More than 15 additional cities are currently engaged in discussions about establishing a standardized cooling tower registration.

Reaction to prevention

Legionella outbreaks can be consistently prevented through implementation of a properly designed water management plan, according to information published in the CDC’s June 2016 Vitalsigns. That year’s report also found that 9 out of 10 outbreaks could have been prevented.

Soon after this finding, the Centers for Medicare and Medicaid Services (CMS) in the United States directed all federally-funded health care facilities to implement water management plans to control Legionella and other waterborne pathogens.

Numerous jurisdictions around the world have established similar requirements for proactive management of cooling towers and other building water systems, according to a study titled “Overview and Comparison of Legionella Regulations Worldwide” published in the American Journal of Infection Control.

With scientific evidence that Legionella risks can be reliably and consistently controlled, civil and possible criminal liability questions arise. Years ago, it could have been argued that the relationship between engineered water systems and illness and death was neither known nor established. That argument cannot be made anymore.

Today we know Legionella is spread through contaminated aerosols in the form of mist or droplets. Further, we know cooling towers, decorative fountains and intermittently used showers are often the source. We know that if those systems are managed properly, risks of illness and death can be significantly reduced.

The safety of engineered water systems needs to be compared to boilers, escalators, elevators and other critical health and safety systems in buildings. These systems are mandated by well-established safety regulations because our society has a very low tolerance for engineered systems that have a potential to result in injury or even death. Facility managers must ask the critical question: Why shouldn’t building water systems be regulated in the same way as other building safety requirements?

Preventing Legionnaires’ Disease

Despite the diversity and complexity of the ecosystems within building water systems, it is possible to develop consistent risk management across a large portfolio. There are examples of enterprise solutions effectively managing risk in hospitality, health care, residential, commercial and industrial portfolios. What makes these enterprise solutions successful is the consistency with which the water safety plans are developed and implemented. Some key steps include:

  • Identifying building water systems where Legionella control measures are needed

  • Assessing how much risk the hazardous conditions in those water systems pose

  • Applying control measures to reduce the hazardous conditions

  • Documenting that the program is running as designed and monitoring risk factors for the various systems

  • Writing protocols for how to respond when elevation of risk is identified

  • Validation sampling that confirms the program is successfully managing Legionella exposure risks

Some of the issues that generate risk are driven by other goals such as water conservation. If water flows are greatly reduced without consideration for water age, temperature loss, stagnation and loss of disinfectant to control biofilm growth, some conservation efforts may result in the creation of a deadly hazard. Water conservation efforts must align with management of Legionella risks.

Other risk factors include nearby construction which can dislodge biofilm and free Legionella into the water distribution system. Water main breaks can introduce dirt and debris into the water system, using up the residual disinfectant in the water and leaving less to fight pathogens. In addition, temperature settings or other factors that impact water temperatures can lead to increased risk. Legionella grows best between 77 and 108 Fahrenheit.

The Water Research Foundation has developed an educational campaign to inform building owners about the shared responsibility between water suppliers and building managers and owners to control Legionella risks.

Years ago, we would respond to cases, conduct building-level mitigation and then move on. But the time has come to realize this disease can be managed from a prevention standpoint.

The confirmation of 7,500 Legionnaires’ disease cases last year in the United States is driving a hard look from state attorneys general, the insurance industry and plaintiffs’ lawyers. They are not going to continue to accept “I didn’t know” as a legitimate defense against risk and responsibility.