With outbreaks of Legionnaires’ disease increasing, hospitals should establish water management teams that include infection preventionists and launch an investigation even if they detect only one confirmed case of Legionella, according to recently updated guidelines1 by the CDC.
The CDC analyzed 27 building-related outbreaks between 2000-2014, finding that 15% occurred in hospitals and 19% in long-term care facilities.2
“The outbreaks in long-term care facilities and hospitals affected more people and caused more deaths than outbreaks in other locations,” Tom Frieden, MD, director of the CDC, noted at a recent press conference. “They accounted for 85% of deaths, while hotel and resort outbreaks accounted for 6%. This reflects the higher rate of underlying illness in patients who are infected in healthcare facilities.”
In analyzing the outbreaks, the CDC determined that most are preventable by improving water management systems. Problems identified included inadequate water disinfectant levels and other maintenance and equipment breakdowns. As IPs are well aware, Legionella can proliferate in a water supply that is not sufficiently treated or allows reservoirs to back up and form. The pathogen can be aerosolized and inhaled in mist from showers, sinks, and other sources of the potable water supply.
The disease gets its name from an outbreak at a meeting of the American Legion in 1976 in Philadelphia. In one of its more famous investigations, the CDC cracked the case by tracing the then-novel pathogen to the air conditioning system in the hotel.
“Legionnaires’ disease is a serious lung infection,” Frieden said. “It causes pneumonia, and symptoms include cough, shortness of breath, high fever, muscle pains, and headaches. About 10% of people who get this infection will die from it, and it’s of particular risk to the elderly and those with suppressed immune systems or other underlying health problems.”
Sporadic Cases Under the Radar
As part of the analysis, the CDC looked at 415 cases of Legionnaires’ disease and 65 deaths. Although the analysis looked at outbreak-associated cases, it is thought that sporadic cases of Legionella are occurring under the proverbial radar.
“It’s just easier to identify the problem if you have many cases in an outbreak,” Frieden said. “While we still need to learn more about Legionnaires’ disease, it’s clear that people are unnecessarily getting sick and dying from preventable infections.”
Though some confounding factors may be at play, Legionnaires’ disease is increasing, with the number of cases quadrupling from 2000 to 2014. About 5,000 people are infected annually in the U.S. during an average of 20 outbreaks a year.
“We believe that the increase is real and it’s likely due to a combination of factors including the increasing number of people who are at risk for Legionnaires’ disease because of the aging of the population, the increase in chronic illness, and the increase in immune suppression through use of medications to treat a variety of conditions,” Frieden said.
Other factors include aging plumbing infrastructure, increased diagnostic tests, and more reliable reporting of infection.
“The outbreaks are costly — for one year alone, insurers paid an estimated $434 million in hospitalization claims for Legionnaires’ disease nationally,” he says.
While outbreaks in healthcare are usually traced back to the potable water system, community outbreaks can occur if Legionella is aerosolized in plumes from HVAC cooling towers atop buildings, decorative fountains, and hot tubs.
Healthcare providers should test for Legionnaires’ disease in people with pneumonia, especially those requiring intensive care or who recently stayed in a healthcare facility, hotel, or traveled on a cruise ship, Frieden said. The CDC recommends testing by culture of lower respiratory secretions or the Legionella urinary antigen test.
Hospital Outbreaks
Hospitals with frail patient populations may figure prominently in outbreaks in the community. For example, a Legionnaires’ disease outbreak in Flint, MI, in 2014 and 2015 totaled 91 cases.
“Fifty of those — so more than half — were linked to a single hospital,” says Cindy Whitney, MD, chief of the CDC respiratory diseases branch. “I want to emphasize that hospitals really are vulnerable to Legionnaires’ disease outbreaks. They have patients that are older and have susceptible conditions, so it’s really important for every hospital to have a water management plan and to be actively looking for Legionnaires’ disease among their patients.”
Hospitals should take a multi-faceted approach that includes testing periodically, checking water temperatures and chlorine levels.
“Testing can be a good adjunct to really make sure your water is clean, but we want to emphasize that you can’t rely too much on testing,” she says. “You really need all these other things that you’re checking to make sure your water is safe and you’re preventing Legionella growth.”
In that regard, hospital water management teams should identify areas where Legionella could grow and spread, including patient rooms, ICUs, dialysis, and hydrotherapy.
“Think about all of the places where patients can be exposed to contaminated water,” according to the CDC’s new guidelines. “Don’t forget about ice machines, heater-cooler units used on cardiopulmonary bypass, and respiratory therapy equipment.”
IPs and their colleagues should also be watchful for any signs of Legionella in immune-suppressed patients, such as those receiving bone marrow and other transplants, as well those in treatment for cancer.
The CDC recommends beginning a Legionella outbreak investigation if one or more cases of “definite” healthcare-associated Legionnaires’ disease is detected. That is defined as a patient who has spent at least 10 days prior to onset of illness in the facility, which accounts for the pathogen’s incubation period. Outbreak investigations should also be initiated upon detection of two or more “possible” cases of healthcare-associated Legionnaires’ disease. Possible cases are defined as patients who spent part of the 10-day incubation period before symptoms began at the same facility and are identified within six months of each other.
According to the CDC, key elements of a full investigation include the following:
- working with local and/or state health department staff,
- reviewing medical and microbiology records,
- actively identifying all new and recent patients with healthcare-associated pneumonia and testing them for Legionella,
- developing a line list of cases,
- evaluating potential environmental exposures,
- performing an environmental assessment and conducting environmental sampling,
- subtyping and comparing clinical and environmental isolates, and
- decontaminating environmental sources
REFERENCES
- CDC. Developing a Water Management Program to Reduce Legionella Growth & Spread in Buildings. A Practical Guide to Implementing Industry Standards. June 6, 2016.
- CDC. Vital Signs: Deficiencies in Environmental Control Identified in Outbreaks of Legionnaires’ Disease — North America, 2000–2014. MMWR 2016;65(22):576 – 584.
