MMWR Vol. 65 / Early Release

MMWR Early Release Vol. 65, Early Release June 07, 2016

PDF Vital Signs: Deficiencies in Environmental Control Identified in Outbreaks of Legionnaires’ Disease — North America, 2000–2014 Laurel E. Garrison, MPH; Jasen M. Kunz, MPH; Laura A. Cooley, MD; et al. MMWR Morb Mortal Wkly Rep 2016;65(Early Release) During 2000–2014, the rate of reported cases of Legionnaires’ disease increased from 0.42 to 1.62 per 100,000 persons. CDC evaluated and categorized maintenance deficiencies for building water systems in 23 investigations of Legionnaires’ disease outbreaks that occurred during 2000–2014. Of these, all had at least one deficiency and almost half had deficiencies in two or more categories. Properly implemented maintenance programs, as outlined in a new industry standard published in 2015, could reduce growth and transmission of Legionella, the bacterium that causes Legionnaires’ disease.

Vital Signs: Deficiencies in Environmental Control Identified in Outbreaks of Legionnaires’ Disease — North America, 2000–2014 | MMWR

MMWR Early Release Vol. 65, Early Release June 07, 2016

PDF

Vital Signs: Deficiencies in Environmental Control Identified in Outbreaks of Legionnaires’ Disease — North America, 2000–2014

Early Release / June 7, 2016 / 65

Laurel E. Garrison, MPH1; Jasen M. Kunz, MPH2; Laura A. Cooley, MD1; Matthew R. Moore, MD1; Claressa Lucas, PhD1; Stephanie Schrag, DPhil1; John Sarisky, MPH2; Cynthia G. Whitney, MD1 (View author affiliations)

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Key Points

• Legionnaires’ disease is a lung infection that is fatal for about one in 10 persons who become infected. Legionella, the bacterium that causes Legionnaires’ disease, grows well in warm water, but can be killed by disinfectants, such as chlorine. Persons can get Legionnaires’ disease when they breathe in small droplets of water contaminated withLegionella.

• Persons most likely to get Legionnaires’ disease are those aged ≥50 years, smokers, and persons with underlying medical conditions, such as chronic lung disease or weakened immune systems.

• Legionella grows best in building water systems that are not well maintained, especially where levels of chlorine or other disinfectants are low and water temperatures are optimal for its growth. Legionnaires’ disease outbreaks most often occur in hotels, long-term care facilities, and hospitals. The most common sources are potable water (e.g., drinkable water used for showering), cooling towers, hot tubs, and decorative fountains.

• The key to preventing outbreaks is good management of building water systems, according to new industry standards. Outbreaks have occurred because of process failures (65%), human errors (52%), equipment failures (35%), external conditions (35%), or a combination of these (48%). Building owners and managers should determine if their building water systems are at increased risk for Legionella growth and spread. If so, they should develop and use aLegionella water management program according to the new industry standards (http://www.cdc.gov/legionella/WMPtoolkit).

• Additional information is available athttp://www.cdc.gov/vitalsigns.

Abstract

Background: The number of reported cases of Legionnaires’ disease, a severe pneumonia caused by the bacterium Legionella, is increasing in the United States. During 2000–2014, the rate of reported legionellosis cases increased from 0.42 to 1.62 per 100,000 persons; 4% of reported cases were outbreak-associated. Legionella is transmitted through aerosolization of contaminated water. A new industry standard for prevention ofLegionella growth and transmission in water systems in buildings was published in 2015. CDC investigated outbreaks of Legionnaires’ disease to identify gaps in building water system maintenance and guide prevention efforts.

Methods: Information from summaries of CDC Legionnaires’ disease outbreak investigations during 2000–2014 was systematically abstracted, and water system maintenance deficiencies from land-based investigations were categorized as process failures, human errors, equipment failures, or unmanaged external changes.

Results: During 2000–2014, CDC participated in 38 field investigations of Legionnaires’ disease. Among 27 land-based outbreaks, the median number of cases was 10 (range = 3–82) and median outbreak case fatality rate was 7% (range = 0%–80%). Sufficient information to evaluate maintenance deficiencies was available for 23 (85%) investigations. Of these, all had at least one deficiency; 11 (48%) had deficiencies in ≥2 categories. Fifteen cases (65%) were linked to process failures, 12 (52%) to human errors, eight (35%) to equipment failures, and eight (35%) to unmanaged external changes.

Conclusions and Implications for Public Health Practice: Multiple common preventable maintenance deficiencies were identified in association with disease outbreaks, highlighting the importance of comprehensive water management programs for water systems in buildings. Properly implemented programs, as described in the new industry standard, could reduce Legionella growth and transmission, preventing Legionnaires’ disease outbreaks and reducing disease.