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What is Legionnaires' disease? (2015)
01:03 - Source: CNN

Editor’s Note: Dr. Anne Schuchat is the acting director of the US Centers for Disease Control and Prevention.

Story highlights

Researchers looked at Legionnaires' cases in 20 states and one city

Cases were linked to hospitals, long-term care facilities and outpatient clinics

"People should go to the hospital to get better, not to get a new infection," CDC director says

CNN  — 

Over forty years ago, a group of American Legionnaires returning from a convention in Philadelphia were sickened with a mystery respiratory disease. Sadly, some died, and many others were hospitalized. This sudden illness prompted the Centers for Disease Control and Prevention to launch the agency’s largest outbreak investigation to date, sending more than 20 disease detectives into the field to try to find the source and activating hundreds at headquarters to evaluate specimens in order to find the source of the severe pneumonia.

Their investigation ultimately identified a bacterium, Legionella, for the first time associated with the hotel’s air-conditioning system that triggered severe cases of pneumonia. Four decades have passed since Legionnaires’ disease was defined, yet it is increasing in incidence and now recognized that many infections in the United States can be prevented.

One 2016 study showed that, following hotels, long-term care facilities and hospitals are the most common types of buildings associated with Legionnaires’ disease outbreaks that CDC investigates. In CDC’s most recent Vital Signs report, our experts gathered case data from 20 states and one large city with the goal of learning more about Legionnaires’ disease infections associated with health care facilities and identifying ways to prevent new infections.

This is the first time CDC has looked at state and city level data on healthcare source for Legionnaires’ disease, and we found 76% of the areas that were analyzed had residents who definitely became infected with Legionnaires’ disease during a stay at a health care facility. Among cases with definite health care exposure, four out of five were associated with long-term care facilities, one out of five with hospitals, and some had stayed in both. Among cases with possible health care exposure, 13% were associated with long-term care facilities, 49% with hospitals, and 26% with outpatient clinics.

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    At CDC, we believe people should go to the hospital to get better, not to get a new infection. Because of the vulnerable population they serve, it’s especially important that health care facilities have a water management program in place, and a team to execute the program.

    Each part of the team has a role to play:

    • Doctors can “think Legionella” when treating patients at increased risk for Legionnaires’ disease who have health care-associated pneumonia.
    • Doctors can evaluate patients with pneumonia using tests that will detect Legionnaires’ disease.
    • Health care facility leaders can maintain a safe water program by building a team and executing a safe water plan.
    • Clinicians and laboratory staff can quickly alert local public health authorities if a Legionnaires’ disease case is identified, and work with them to identify the source of infection and other cases.

    Since 1976, we’ve learned a lot about the origin of a rare, mysterious disease. Now we must turn attention to applying what we’ve learned about how to prevent it.