In an unexpected and especially nasty surprise, about a dozen cruise ship passengers fell ill to Legionnaires’ disease on two separate ships. Between November 2022 and July 2024, 10 individuals were hospitalized, and the CDC has traced each case back to private hot tubs on the ships.
The new report released by the Centers for Disease Control shows that private hot tubs — a luxury amenity offered to passengers, often located on private balconies — are the perfect breeding ground for the disease, which presents similarly to pneumonia.
Private hot tubs are not required to be cleaned and sanitized as frequently nor as precisely as public water features on cruise ships, which creates an opportunity for Legionella bacteria to grow to levels where infection is possible. The outbreak has caused the biggest investigation since 2008.
The hot tubs on the first ship “were found to be operating for months in a manner conducive to Legionella growth, which included maintaining a water temperature in the Legionella growth range (between 77 and 113 degrees Fahrenheit) for multiple days without draining and operating with no residual disinfectant,” the CDC says.
Even though the cruise lines claim they adhered to current CDC requirements for operating and maintaining private hot tubs — they must only be shock-chlorinated, drained, and refilled weekly or between occupancies — the measures taken did not prevent bacteria growth.
As a result, the recommended maintenance regimen for such hot tubs may be altered. The CDC concluded there’s a need for more in-depth assessments on private hot tubs. They advise “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.”
Thankfully, no fatalities have been reported in relation to the outbreaks. But passenger eagerness to use private hot tubs on their cruise vacations might take a dip for the foreseeable future.
