Passengers who recently sailed aboard Royal Caribbean’s Symphony of the Seas are being notified that a fellow guest has been diagnosed with Legionella, the bacteria that causes Legionnaires’ disease.
The cruise line issued a letter alerting guests and outlining steps taken in response.
“Your health and safety are always our top priority, and we are reaching out for your awareness,” the letter from Royal Caribbean began.
“The CDC [Centers for Disease Control and Prevention] has advised that while they are unsure where exposed, a guest who recently sailed on Symphony of the Seas was later diagnosed with Legionella,” it continued.
Legionnaires’ disease, according to the CDC, is a serious type of pneumonia caused by inhaling droplets of water containing Legionella bacteria.
The CDC says outbreaks are often associated with large or complex water systems like those found in hotels, hospitals, and, yes, cruise ships.
The bacteria grow best in warm water and can be spread through showers, hot tubs, and decorative fountains. It does not, however, spread from person to person, says the CDC.
In response, Royal Caribbean has implemented heightened sanitation measures and is following CDC cleaning guidelines as a precaution.
The cruise line does not specify the date of the voyage the infected passenger had been on, but the 5,518-guest ship is currently sailing a series of 7-night cruises from its homeport in New York to Port Canaveral, Florida; Nassau, Bahamas; and its private island destination, Perfect Day at CoCo Cay.
People who are exposed to Legionella bacteria can take 14 days or longer to experience symptoms of Legionnaires’ disease. These include cough, fever, headaches, muscles aches, and shortness of breath, according to the CDC.
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Other symptoms may include confusion, diarrhea, or nausea, says the CDC.
But the CDC also notes that “most healthy people exposed to Legionella don’t get sick.”
For others, however, the risk increases. This includes people who are or were smokers, 50 years of age of older, or who have or had serious health issues like chronic lung disease, cancer, a weakened immune system, diabetes, or kidney or liver failure.
Anyone who recently sailed on Symphony of the Seas experiencing symptoms should see their doctor.
Outbreaks on the Rise
It is estimated that nearly 6,000 people a year develop Legionnaires’ disease, according to the Occupational Safety and Health Administration (OSHA).
However, that figure is considered low due to the similarities between Legionnaires and pneumonia.
The CDC says 9 of 10 outbreaks of the disease comes from “preventable” water management. This includes proper disinfecting of hot tubs, which are tested and checked regularly on Royal Caribbean vessels.
In fact, just last October and November 2024, Royal Caribbean sent out similar alerts that Legionella had been reported on two separate sailings on the 228,081-gross-ton Symphony of the Seas.
Around the same time, a CDC investigation revealed outbreaks of Legionnaire’s Disease connected to hot tubs aboard two unidentified cruise ships.
Following the review, the authority issued more rigorous standards for hot tub maintenance on cruise ships.
Read Also: Is it Safe to Go on a Cruise – All You Need to Know
The CDC has been busy in 2025 dealing with a banner year in cruise ship outbreaks.
While in 2024, there were only 18 illness outbreaks on US vessels during the entire year, there have been 17 outbreaks by May 29, 2025, indicating the year may be lining up to be a record year for passenger illnesses.
The majority of the outbreaks have been connected to norovirus, a highly contagious virus that leads to vomiting and diarrhea.
