Legionnaires’ disease in LTC facilities: A hidden threat

In the summer of 2013, the Wesley Ridge Retirement Community in Reynoldsburg, Ohio, experienced the largest and deadliest Legionnaires’ disease outbreak in state history. The assisted- and independent-living facility saw six people die and another 33 become seriously ill. The victims ranged in age from 63 to 99 and included residents, visitors and one employee.

For most people, Legionnaires’ disease is something from the history books, a vague memory of Philadelphia conventioneers falling ill in the 1970s. In fact, outbreaks of this often-fatal form of pneumonia, including in long-term-care (LTC) facilities, have been increasing for several years in the United States. In just the past three years, nursing home and senior living outbreaks have occurred in Baltimore; Pittsburgh; Cleveland; Clearwater, Fla.; Jacksonville, Fla.; and Florence, Ala. The worst outbreak in an LTC facility in North America occurred in 2005 at the Seven Oaks Home for the Aged in Toronto, Ontario, where 23 residents died and 112 other people fell ill.

A little background

Legionnaires’ disease—clinically known as legionellosis—is a form of pneumonia caused by waterborne bacteria of the genus Legionella. It carries a mortality rate of 40 percent when acquired in hospitals.

More than 50 species and subspecies of Legionella exist, several of which can infect people. By far the most common is Legionella pneumophila serogroup 1. The bacteria are ubiquitous and usually harmless in the environment, but they easily can grow in warm, stagnant water. In certain circumstances, especially in institutions housing the elderly or in those with chronic illness, Legionella can multiply and cause pneumonia when people aspirate tiny particles while drinking water or showering.

Since 2001, Centers for Disease Control and Prevention (CDC) surveillance reports have stated that Legionella is the single most commonly reported pathogen associated with drinking water outbreaks in the United States. Voluntarily reported cases of Legionnaires’ disease tripled from 2000 to 2009, to 3,522 annually. This amount, however, is now known to be a vast underestimate, and some estimates of incidence exceed 10,000 cases per year. As many as 70 percent of all water systems in buildings taller than three stories are contaminated with Legionella. Because it takes specialized laboratory testing to diagnose it, the disease is severely underdiagnosed in long-term care.

Special concerns for senior living

The increase in cases of Legionnaires’ disease is of particular concern for owners and managers of LTC facilities. Although anyone can become infected under certain circumstances, Legionnaires’ disease principally affects those who are susceptible due to age, illness or compromised immune systems.

Outbreaks usually are followed by lengthy, costly litigation. The aforementioned Toronto outbreak, for instance, resulted in a $600 million class action lawsuit. Under the right circumstances—detectable contamination of the water source, the right species of Legionella, a susceptible individual and sufficient intensity of exposure—victims of Legionnaires’ disease easily can establish the basis for a valid claim, according to Russell Nassof, JD, founder of RiskNomics, a Scottsdale, Ariz.-based risk management assessment firm and an expert in Legionella litigation. Negligence can be alleged if a responsible party “knew or should have known” that a problem existed with the water and failed to maintain and clean up the system, resulting in punitive damages, Nassof says.

The need to take action likely is soon to be a part of building codes. In mid-May, ASHRAE (formerly the American Society of Heating, Refrigerating and Air-Conditioning Engineers) announced the impending fourth public review of a draft of ASHRAE Standard 188P, Legionellosis: Risk Management for Building Water Systems. The organization says 188P would be the first set of standardized requirements specific to the building industry for management of the risks associated with amplified growth of and exposure to Legionella. The latest draft, which is expected to be approved and made available this summer, will recommend that nursing home facility managers implement stronger safeguards through risk assessment and risk management practices. ASHRAE is not indicating when it will finalize the standard, but finalized ASHRAE standards are the basis for many municipal building codes.

Central to the process that may be required by the standard will be assembling a team to be responsible and accountable for building water system safety. This team will conduct a complete survey of potential problems in the water system, such as dead legs where water has sat for a long period of time. If significant risk factors exist, then the team will need to prepare a plan that identifies and establishes control measures at critical points, verifies the control measures are implemented within specific performance limits and validates that the plan is effective in preventing Legionnaires’ disease.

The CDC doesn’t yet recommend routine environmental cultures for hospitals and nursing homes. In contrast, the World Health Organization and many public health agencies in Europe and Asia do recommend routine environmental surveillance for Legionella.

The good news is that compliance with ASHRAE Standard 188P, once it is finalized, will help protect facilities against negligence claims in Legionella-related lawsuits.

Another concern is that an outbreak of Legionnaires’ disease also can lead to media scrutiny, unsubstantiated rumors and even panic, causing widespread disruption of services. Residents, family members and facility staff members must be educated and reassured. An outbreak brings in public health officials, and the facility is closed to new residents in the interim.

Finding the problem

Legionnaires’ disease involves a significant degree of ambiguity, from whether and how to test to what level of Legionella constitutes a clear danger, to the means needed to remediate the situation. The authors of this article are longtime experts in the clinical pathology of this pathogen and have conducted advanced analyses of remediation solutions. Our evidenced-based work reveals that less-costly interventions, carried out under the supervision of infection control staff, are the most efficacious, least disruptive and the most economical to the facility. Particularly following an outbreak, many organizations waste resources on outside consultants with little experience in public health measures when they should rely on infection control staff who are trained to apply evidence-based medical practices for infectious disease outbreaks.

The amount of Legionella in the water may indicate risk, but how to assess the level is one of the many ambiguities. Although a common means is a measure of colony-forming units per milliliter of water in a sample, we and others have demonstrated it to be an inconsistent metric in terms of assessing risk of contracting Legionnaires’ disease.

The percentage of distal sites (samples taken at faucets and showerheads) with Legionella correlates with infection risk. Specifically, a prospective study of 20 hospitals found that when Legionella is present in more than 30 percent of distal sites, patients tended to contract Legionnaires’ disease. This is not an absolute indicator, so we recommend testing a minimum of 10 distal sites (with another site per 100 additional residents) in addition to all hot water tanks. Sample sites where the oldest and sickest nursing home residents are concentrated.

Perform routine cultures for Legionella at least once a year. If 30 percent of cultures come back positive, preventive measures are needed.

Another area of ambiguity is diagnosing the condition. Legionnaires’ disease symptoms are those of pneumonia: fever, cough, productive sputum. Treating this disease as pneumonia, however, is highly problematic. Antibiotics used for common pneumonia are ineffective against Legionnaires’ disease, and a fatality can occur in less than two weeks. A few clues may raise suspicion: A fever above 102 degrees F and diarrhea signal possible Legionnaires’.

The diagnostic test most used is the Legionella urinary antigen test. It is reasonably accurate but only detects L. pneumophila serogroup 1. That still accounts for 80 percent of Legionella infections, however.

Fixing the problem

If Legionella is found in the water supply and residents have contracted Legionnaires’ disease, disinfection of the drinking water is obviously needed. If Legionella is found in enough sites before a resident becomes ill, however, we recommend an innovative approach using intermittent disinfection with intensive monitoring. This approach is inexpensive, and long-term evaluation suggests greater efficacy.

Disinfection modalities can be categorized as either focal or systemic. Focal disinfection refers to disinfection directed at only a portion of a water system, usually the point of entry from the municipal water main or point of use, such as a faucet. Systemic disinfection refers to disinfection directed at the entire water system by providing a disinfectant residual throughout the water system, especially the distal sites.

Point-of-use disposable filters are a focal method to control Legionella in restricted areas in which bedridden residents are congregated. These filters can be applied to a faucet or showerhead quickly and can supplement long-term disinfection options. A focal approach might be applied if the distal site positivity is low and cases have not occurred. Facilities should ensure that the filters they use have been validated by reputable third parties.

A disinfection system installed in the water supply might be applied in facilities experiencing many cases and where the distal site positivity for Legionella is high. Two systemic disinfection methods have proven efficacious against Legionella in laboratory studies and in hospital water supplies: copper-silver ionization and chlorine dioxide.

Numerous investigators worldwide have documented the efficacy of copper-silver ionization in eradicating Legionella from hospital water distribution systems. In this system, a flow cell chamber containing sacrificial copper/silver electrodes is attached to the water supply. A direct current is applied across these electrodes to stimulate the controlled release of ions, which act to starve bacteria of life-sustaining nutrients.

The authors’ major 2011 review of all of the existing modalities for remediation of Legionella, published in Infection Control and Hospital Epidemiology, found that copper-silver ionization appears to be the best available technology today for controlling Legionella colonization in hospital water systems when both ion levels and Legionella cultures are monitored.

If a systemic disinfection system is installed because of occurrence of resident cases, then copper-silver ionization may be the preferred approach given its established track record, especially if the news media have reported the outbreak.

Chlorine dioxide, a synthetic gas, was first used for Legionella control in Europe, where it generally failed. The Special Pathogens Laboratory at the Pittsburgh Veterans Affairs Health System published the first successful controlled evaluation for L. pneumophila in the United States at Geisinger Medical Clinic in Pennsylvania, where it worked.

Maintaining a sufficient residual concentration of chlorine dioxide in the hot water system is challenging. Elevated temperature hastens the conversion of chlorine dioxide to chlorite, which may lead to deleterious health issues. An effective residual of the gas must be maintained throughout an extensive water distribution system.

The decay of chlorine dioxide depends on the water temperature and the distance from generation site to the distribution system. Given its rapid decay in hot water, a higher concentration of chlorine dioxide must be injected at the source to reach an effective concentration at the distal site. Thus, the efficacy of chlorine dioxide may be limited to only cold water supplies, not hot water recirculating lines. The advantage of chlorine dioxide is its lower cost compared to copper-silver ionization for the same capacity.

Conversely, the most prominently used solutions—hyperchlorination and heating and flushing the water distribution system—have significant drawbacks. The first three hospitals in the United States to try hyperchlorination discontinued the practice because it failed to control Legionella and corroded water pipes. Heat and flush is often an effective short-term fix in cases of an outbreak. Vendors experienced with this method should oversee the process, as it invariably fails if healthcare facility personnel oversee the process. Infection control practitioners need to document the temperature at the tap and duration of the flush.

Ineffective (and expensive) control measures

If a consultant suggests either of the following expensive control measures, management should think again, because the recommendations are not only ineffective but logistically tedious to implement and expensive.

  • Cleaning of distal outlets. Faucets and showerheads are disinfected by immersion in chlorine of high concentration or boiling water. Or these outlets are replaced with new ones. This method only eradicates the Legionella at the outlets, a small proportion of the total Legionella in an existing plumbing system. Legionella can reappear within days or weeks because it is still present throughout the plumbing system.
  • Removing dead legs (unused sections of water pipes). The concept of a “stagnant” aquatic environment in which Legionella readily propagates is an appealing one. Scientific evidence supporting this concept is lacking, however.


In summary, Legionnaires’ disease is under-diagnosed in nursing homes. When it is discovered, it may be in the context of an outbreak. If deaths occur, panic during the outbreak and exorbitant costs from litigation can occur.

A major benefit of infection control participation is the avoidance of poor decision-making during an outbreak. Inexperienced consultants and healthcare facility managers often make costly and useless recommendations to management. Prevention can be low-cost and effective. We now are applying a new approach for nursing homes and other LTC facilities that should be more effective, easier to operate and must less expensive than installing a permanent disinfection system.

The impending ASHRAE 188P standard and growing awareness among regulatory bodies may be the tipping point for LTC providers to take immediate steps to find out their risk exposure and act to prevent outbreaks in the name of resident safety.

Yusen E. Lin, PhD, MBA, is visiting professor of civil and environmental engineering at the University of Pittsburgh and a professor and director of the Center for Environmental Laboratory Services at the National Kaohsiung Normal University in Taiwan. Victor L. Yu, MD, is a professor of medicine at the University of Pittsburgh and medical director of the Special Pathogens Laboratory in Pittsburgh.

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