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Legionella reduction after conversion to monochloramine for residual disinfection
Author(s) -
Weintraub June M.,
Flannery Brendan,
Vugia Duc J.,
Gelling Lisa B.,
Salerno James J.,
Conroy Michael J.,
Stevens Valerie A.,
Rose Charles E.,
Besser Richard E.,
Fields Barry S.,
Moore Matthew R.
Publication year - 2008
Publication title -
journal ‐ american water works association
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.466
H-Index - 74
eISSN - 1551-8833
pISSN - 0003-150X
DOI - 10.1002/j.1551-8833.2008.tb09609.x
Subject(s) - legionella , chloramine , legionnaires' disease , outbreak , colonization , disease transmission , environmental science , waterborne diseases , disinfectant , water disinfection , medicine , chlorine , environmental engineering , environmental health , legionella pneumophila , microbiology and biotechnology , bacteria , chemistry , biology , virology , genetics , organic chemistry , pathology
Previous studies have shown that monochloramine disinfection of municipal water supplies is associated with decreased risk of healthcare‐associated Legionnaires— disease. A twoyear, prospective environmental study was conducted to determine whether converting from chlorine to monochloramine for water disinfection would decrease Legionella colonization of hot water systems. Water and biofilm samples were collected from 53 buildings. Prevalence ratios comparing Legionella colonization before and after monochloramine disinfection were adjusted for water system characteristics. Legionella colonized 60% of the hot water systems before monochloramine conversion versus 4% after conversion. The median number of colonized sites per building declined significantly with monochloramine disinfection. Increased prevalence of Legionella colonization was associated with water heater temperatures below 50oC, buildings taller than 10 stories, and interruptions in water service. Although no outbreaks of Legionnaires— disease were found, the study provides support that use of monochloramine in water supplies may reduce Legionella transmission and incidence of Legionnaires— disease.