Norwegian Cruise Line is working with the Centers for Disease Control and Prevention after three passengers who previously sailed aboard Norwegian Prima were diagnosed with Legionnaires’ disease. The cruise line has begun additional testing aboard the ship and, as a precaution, has temporarily closed its public hot tubs and private heated balcony whirlpools while the investigation continues.
The important point for cruisers is that there is currently no confirmation that the passengers contracted Legionnaires’ disease aboard Norwegian Prima. According to a letter Norwegian Cruise Line sent to guests, the three cases involve passengers who sailed on the ship during May and July 2026, but investigators have not determined whether their exposure came from the ship’s water system or from another source during their travels.
The letter, dated August 29 and later shared by a passenger on Reddit, says NCL is working with the CDC as part of the agency’s standard investigation process. Norwegian says it has already tested equipment and fixtures that use water, including hot tubs, showers and faucets, and that all test results received so far have been negative. Additional testing is planned.
What Norwegian Prima Passengers Are Being Told
In its notice, Norwegian Cruise Line explained that Legionnaires’ disease is a serious form of pneumonia caused by Legionella bacteria. People generally become infected by breathing tiny droplets of water containing the bacteria rather than through normal person-to-person contact.
NCL says that while testing continues, all public hot tubs and private balcony heated whirlpools will remain closed. They will reopen only after sampling has been completed and any necessary remediation has been performed in accordance with CDC guidelines.
That precaution is notable because hot tubs have previously been associated with Legionnaires’ disease cases aboard cruise ships. A 2024 CDC investigation looked at two outbreaks involving two unnamed cruise ships and concluded that private balcony hot tubs were the most likely source of exposure. Across those two outbreaks, the CDC investigated 12 cases reported between November 2022 and June 2024.
Hot tubs can create particularly favorable conditions for Legionella because they combine warm water with jets that produce small airborne droplets. The CDC has also noted that potable water systems can occasionally be a source of the bacteria, which is why investigations typically include testing showers, faucets and other parts of a ship’s water system as well.
What Is Legionnaires’ Disease?
Legionnaires’ disease is a type of pneumonia caused by Legionella bacteria. Symptoms can include cough, shortness of breath, fever, muscle aches and headaches, generally developing within two to 14 days following exposure.
The illness can become serious, particularly for older adults and passengers with certain underlying health conditions including people 50 and older, current or former smokers, people with chronic lung disease and those with weakened immune systems as groups that can face a greater risk.
For most healthy passengers, however, the risk of developing Legionnaires’ disease remains relatively low. It is also important to distinguish this from outbreaks such as norovirus. Legionnaires’ disease generally does not spread from one passenger to another, so this is not a situation where simply being around someone who is infected would normally expose another cruiser.
This Isn’t Norwegian Prima’s First Legionnaires Investigation
There is another piece of history that makes the latest investigation worth watching. Norwegian Prima was involved in a similar situation shortly after the ship entered service.
In February 2023, Norwegian notified passengers after two guests who sailed aboard Prima on its November 19, 2022 voyage were diagnosed with Legionnaires’ disease after completing their travels. At the time, NCL also worked with the CDC and tested water-related equipment including hot tubs, showers and faucets. As with the current investigation, it had not been established whether either passenger contracted the illness aboard the ship.
More recently, Norwegian dealt with another investigation involving Norwegian Encore. Two passengers who traveled aboard Encore in December 2025 were subsequently diagnosed with Legionnaires’ disease. NCL confirmed in February 2026 that it was working with the CDC to investigate those cases, with testing again focusing on hot tubs, showers and faucets.
Should You Be Worried If You’re Sailing Norwegian Prima?
There are three reported cases involving passengers who sailed during two different months, and Norwegian says its testing aboard the ship has so far been negative. The CDC investigation is still trying to determine whether the passengers shared an exposure aboard Prima or whether the cases are coincidental and originated somewhere else during their travels.
That distinction matters. Cruise passengers visit hotels, airports, restaurants, pools, spas and ports before, during and after a cruise, all of which can complicate a Legionnaires’ investigation. The disease also frequently isn’t diagnosed until a traveler has returned home, making it more difficult to identify exactly where the exposure occurred. The CDC specifically notes that cruise-related clusters can be difficult to detect for this reason.
For anyone boarding Norwegian Prima in the immediate future, the most visible impact appears to be the closure of the ship’s hot tubs and heated balcony whirlpools while testing continues. Norwegian has not announced any cancellation or interruption of Prima’s cruises related to the investigation.
If you recently sailed aboard Norwegian Prima and develop symptoms such as a cough, shortness of breath, fever, muscle aches or headaches within the period following your trip, the CDC recommends seeking medical attention and telling your healthcare provider about your recent travel.
