Vital Signs: Health Care–Associated Legionnaires’ Disease Surveillance Data from 20 States and a Large Metropolitan Area — United States, 2015
Authors: Elizabeth A. Soda, Albert E. Barskey, Priti P. Shah, Stephanie Schrag, Cynthia G. Whitney, Matthew J. Arduino, Sujan C. Reddy, Jasen M. Kunz, Candis M. Hunter, Brian H. Raphael, Laura A. Cooley
Journal: MMWR Morbidity and Mortality Weekly Report (2017)

Background: Legionnaires' disease, a severe pneumonia, is typically acquired through inhalation of aerosolized water containing Legionella bacteria.Legionella can grow in the complex water systems of buildings, including health care facilities.Effective water management programs could prevent the growth of Legionella in building water systems.Methods: Using national surveillance data, Legionnaires' disease cases were characterized from the 21 jurisdictions (20 U.S. states and one large metropolitan area) that reported exposure information for ≥90% of 2015 Legionella infections.An assessment of whether cases were health care-associated was completed; definite health care association was defined as hospitalization or long-term care facility residence for the entire 10 days preceding symptom onset, and possible association was defined as any exposure to a health care facility for a portion of the 10 days preceding symptom onset.All other Legionnaires' disease cases were considered unrelated to health care.Results: A total of 2,809 confirmed Legionnaires' disease cases were reported from the 21 jurisdictions, including 85 (3%) definite and 468 (17%) possible health care-associated cases.Among the 21 jurisdictions, 16 (76%) reported 1-21 definite health care-associated cases per jurisdiction.Among definite health care-associated cases, the majority (75, 88%) occurred in persons aged ≥60 years, and exposures occurred at 72 facilities (15 hospitals and 57 long-term care facilities).The case fatality rate was 25% for definite and 10% for possible health care-associated Legionnaires' disease.Conclusions and Implications for Public Health Practice: Exposure to Legionella from health care facility water systems can result in Legionnaires' disease.The high case fatality rate of health care-associated Legionnaires' disease highlights the importance of case prevention and response activities, including implementation of effective water management programs and timely case identification.* Large or complex water systems, where Legionella has more opportunity to grow and spread, are most often found in commercial, institutional, multiunit residential, health care, and industrial buildings, often with multiple stories.ASHRAE Standard 188 recommends water management for these types of buildings in addition to those in which vulnerable populations, such as immunocompromised or elderly persons, live or are treated.FIGURE.Categorization of confirmed cases of legionellosis* , † reported to the Supplemental Legionnaires' Disease Surveillance System, 2015 Jurisdictions that reported ≥90% of NNDSS cases to SLDSS 2,809 LD cases CFR 7% (206 deaths) 21 jurisdictions Health care-associated 20% (553/2,809 LD cases) CFR 12% (66 deaths) De nite 3% (85/2,809 LD cases) CFR 25% (21 deaths) 16 of 21 jurisdictions (76%) Possible 17% (468/2,809 LD cases) CFR 10% (45 deaths) 20 of 21 jurisdictions (95%) Not health care-associated 80% (2,256/2,809 LD cases) CFR 6% (140 deaths) Jurisdictions that did not report ≥90% of NNDSS cases to SLDSS 650 LD cases CFR 6% (37 deaths) 30 jurisdictions 3,459 LD cases 57 Pontiac fever cases Total legionellosis cases reported to SLDSS 3,516 cases Abbreviations: CFR = case fatality rate; LD = Legionnaires' disease; NNDSS = National Notifiable Diseases Surveillance System; SLDSS = Supplemental Legionnaires' Disease Surveillance System.* Legionellosis cases include Legionnaires' disease and Pontiac fever, a mild influenza-like illness.† A total of 6,079 cases of legionellosis were reported to NNDSS in 2015.