The US Centers for Disease Control and Prevention (CDC) reported outbreaks of Legionnaires' disease on two cruise ships, affecting 12 individuals between November 2022 and July 2024.

The disease, a severe type of pneumonia caused by Legionella bacteria, was traced back to private-use hot tubs.

The cruise ships operated on European, Caribbean, and Mediterranean routes, though the ships' identities were not disclosed by the CDC.

The report highlights the risk of Legionella growth in inadequately maintained hot tubs.

Epidemiologic and laboratory data indicate that hot tubs on private balconies were the probable infection source.

The CDC advises cruise operators to evaluate and improve their water management and maintenance protocols for these devices.

Public health practices should focus on assessing and adapting maintenance operations for private hot tubs to mitigate health risks.