CDC IDs Outbreak Trends Tied to Treated Recreational Water

Outbreaks with confirmed infectious etiology usually caused by <i>Cryptosporidium</i>, <i>Legionella</i>, <i>Pseudomonas</i>.
Outbreaks with confirmed infectious etiology usually caused by Cryptosporidium, Legionella, Pseudomonas.

HealthDay News — Outbreaks associated with treated recreational water with confirmed infectious etiology are usually caused by Cryptosporidium, Legionella, or Pseudomonas, according to research published in the May 18 issue of the US Centers for Disease Control and Prevention's Morbidity and Mortality Weekly Report.

Michele C. Hlavsa, MPH, from the CDC in Atlanta, and colleagues describe 493 outbreaks associated with treated recreational water reported during 2000 to 2014. 

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The researchers found that 58% of the 363 outbreaks with confirmed infectious etiology were caused by Cryptosporidium, 16% by Legionella, and 13% by Pseudomonas. Overall, 24,453 cases were identified in the 363 outbreaks; 89, 4, and 3% were caused by Cryptosporidium, Pseudomonas, and Legionella, respectively. Of the 8 reported deaths, at least 6 occurred in persons affected by outbreaks caused by Legionella. The leading setting was hotels, which were associated with 32% of the 493 outbreaks. The outbreaks had a bimodal temporal distribution: 56% started in June to August, and 9 percent started in March.

"Assessment of trends in the annual counts of outbreaks caused by Cryptosporidium, Legionella, or Pseudomonas indicate mixed progress in preventing transmission," the authors write. "Pathogens able to evade chlorine inactivation have become leading outbreak etiologies."

Abstract/Full Text