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Outbreaks Associated with Treated Recreational Water — United States, 2000–2014
Citation:
Hlavsa, M., B. Cikesh, V. Roberts, A. Kahler, M. Vigar, E Hilborn, Tim Wade, D. Roellig, J. Murphy, L. Xiao, J. Kunz, L. Cooley, K. Yates, V. Hill, M. Beach, K. Fullerton, AND J. Yoder. Outbreaks Associated with Treated Recreational Water — United States, 2000–2014. MORBIDITY AND MORTALITY WEEKLY REPORT. U.S. Department of Health and Human Services, Washington, DC, 67(19):547-551, (2018). https://doi.org/10.15585/mmwr.mm6719a3
Impact/Purpose:
During 14 years of surveillance data, Cryptosporidium leads among among pathogens associated with treated recreational waterborne disease outbreaks; this may be primarily associated with the pathogen's resistance to disinfection. Legionella and Pseudomonas follow in frequency of occurrence. Legionella and Pseudomonas are two pathogens associated with biofilm formation and occur in improperly maintained treated recreational water venues. Waterborne disease outbreak reports are generally useful to the Office of Water as they seek to characterize the public health impact of waterborne contaminants.
Description:
Outbreaks associated with exposure to treated recreational water can be caused by pathogens or chemicals in venues such as pools, hot tubs/spas, and interactive water play venues (i.e., water playgrounds). During 2000-2014, public health officials from 46 states and Puerto Rico reported 493 outbreaks associated with treated recreational water. These outbreaks resulted in at least 27,219 cases and eight deaths. Among the 363 outbreaks with a confirmed infectious etiology, 212 (58%) were caused by Cryptosporidium (which causes predominantly gastrointestinal illness), 57 (16%) by Legionella (which causes Legionnaires' disease, a severe pneumonia, and Pontiac fever, a milder illness with flu-like symptoms), and 47 (13%) by Pseudomonas (which causes folliculitis ["hot tub rash"] and otitis externa ["swimmers' ear"]). Investigations of the 363 outbreaks identified 24,453 cases; 21,766 (89%) were caused by Cryptosporidium, 920 (4%) by Pseudomonas, and 624 (3%) by Legionella. At least six of the eight reported deaths occurred in persons affected by outbreaks caused by Legionella. Hotels were the leading setting, associated with 157 (32%) of the 493 outbreaks. Overall, the outbreaks had a bimodal temporal distribution: 275 (56%) outbreaks started during June-August and 46 (9%) in March. Assessment of trends in the annual counts of outbreaks caused by Cryptosporidium, Legionella, or Pseudomonas indicate mixed progress in preventing transmission. Pathogens able to evade chlorine inactivation have become leading outbreak etiologies. The consequent outbreak and case counts and mortality underscore the utility of CDC's Model Aquatic Health Code (https://www.cdc.gov/mahc) to prevent outbreaks associated with treated recreational water.
URLs/Downloads:
DOI: Outbreaks Associated with Treated Recreational Water — United States, 2000–2014