Private Hot Tubs on Cruise Ships May Carry Legionnaires Risk

Private hot tubs on cruise ships may carry Legionnaires risk, but why? CDC researchers found that different cleaning protocols are often used for private hot tubs, contributing to a number of cruise ship Legionnaires disease outbreaks.

Two outbreaks of Legionnaires disease on cruise ships have been linked to private hot tubs on the cabin balconies of two different passenger liners, resulting in at least a dozen illnesses in recent years, according to a new report issued by federal health officials.

The U.S. Centers for Disease Control and Prevention (CDC) issued an update in the most recent edition of it’s Morbidity and Mortality Weekly Report, outlining the results of investigations into the outbreaks, which occurred between November 2022 and June 2024, suggesting that private hot tubs on some cruise ships may not be disinfected as thoroughly as public ones.

The CDC began investigating the two outbreaks after 12 cases of Legionnaires disease were reported among passengers on two different cruise ships, eight on the first ship and four on the second. The CDC report does not identify the two specific cruise liners involved in the Legionnaires outbreaks.

Testing determined the Legionnaires exposure came from private balcony hot tubs in passenger rooms. These cruise ship hot tubs are not subject to the same stringent operating requirements as hot tubs located in public areas, according to the investigators.

For example, private hot tubs are not subject to the same testing as public ones, and are not required to have automated continuous disinfectant dosing and monitoring or PH monitoring, which are standard for public hot tubs. Additionally, they only have to be drained and refilled weekly or between occupancies, whichever is first.

According to the CDC report, both cruise lines modified the operation and maintenance of the hot tubs by removing the heating elements and draining water between traveler uses. They also increased the frequency of chlorine treatment and cleaning to minimize Legionella growth. However, the report indicates the operating protocols taken by the companies for the private hot tubs are not sufficient to prevent infections.

CDC officials recommend that cruise ship operators inventory their hot tubs across the entire fleet and determine if some design features may increase the risk for Legionella growth and transmission. Every hot tub should be tested for Legionella, and the same protocols should be applied to both public and private hot tubs, CDC researchers concluded.

What is Legionnaires Disease?

Legionnaires’ disease is similar to other types of pneumonia. To help identify the presence of legionella bacteria quickly, your doctor might use a test that checks your urine for legionella antigens — foreign substances that trigger an immune system response. Other tests might include:

• Blood and urine tests
• Chest X-ray, which doesn’t confirm Legionnaires’ disease but can show the extent of infection in your lungs
• Tests on a sample of your sputum or lung tissue

Legionnaires’ disease is treated with antibiotics. The sooner therapy is started, the less likely the chance of developing serious complications. In many cases, treatment requires hospitalization. Pontiac fever goes away on its own without treatment and causes no lingering problems.

For more information about staying safe while on cruise ships and other important outbreak and recall information follow Make Food Safe.