Two Outbreaks of Legionnaires Disease Associated with Outdoor Hot Tubs for Private Use — Two Cruise Ships, November 2022–July 2024
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Sooji Lee, MSPH1; Chris Edens, PhD1; Troy Ritter, PhD2; Luis O. Rodriguez, MS2; Kara Tardivel, MD3; Natalia A. Kozak-Muiznieks, PhD1; Melisa Willby, PhD1; Nancy Ortiz, PhD3; Adam L. Cohen, MD1; Jessica C. Smith, MPH1 (View author affiliations)
Legionnaires disease is a serious pneumonia caused by Legionella bacteria. Hot tubs can be a source of Legionella growth and transmission when they are inadequately maintained and operated.
Epidemiologic, environmental, and laboratory evidence suggests that private balcony hot tubs were the likely source of exposure in two outbreaks of Legionnaires disease among cruise ship passengers. These devices are subject to less stringent operating requirements than are public hot tubs, and operating protocols were insufficient to prevent Legionella growth.
It is important for cruise ship operators to inventory hot tub–style devices across their fleets, evaluate the design features that increase the risk for Legionella growth and transmission, and test for Legionella.
