The U.S. Centers for Disease Control and Prevention’s Vessel Sanitation Program recorded 16 stomach bug outbreaks in 2024, the most since 2012 when 17 such outbreaks occurred.

Norovirus was the most common ailment to strike cruise ships, at 13, with one Salmonella outbreak, one E. coli outbreak and one outbreak where the pathogen that caused it remains unknown. 

Norovirus is the cause of over 90% of all diarrheal outbreaks on cruise ships, the CDC said.

Gastrointestinal illnesses measured by the VSP all cause vomiting, as well as such other symptoms as diarrhea, muscle aches, headaches, fevers and abdominal cramps.

All five outbreaks in December involved norovirus, including two back-to-back outbreaks aboard the Cunard Lines ship Queen Mary 2 with sailing dates between Dec. 14 and Dec. 21 and Dec. 21 and Friday.

The first outbreak aboard the Queen Mary 2 struck 138 of 2,430 passengers and 12 out of 1,237 crewmembers, while the second outbreak affected 326 of 2,565 passengers and 65 of 1,233 crewmembers.

The Queen Mary 2 was the only ship with two outbreaks of the same ailment; the only other ship to be hit with two stomach bugs in 2024 was Royal Caribbean’s Radiance of the Seas, which saw the Salmonella outbreak from Sept. 20 to Sept. 27 and a norovirus outbreak from April 8 to April 22.

While norovirus outbreaks aboard cruises garner attention and lead people to associate the condition with cruising, only around 1% of all norovirus outbreaks happen aboard said ships. But controlling outbreaks on board is tough due to the shared dining areas and close living quarters for those aboard.

• Brad Matthews can be reached at bmatthews@washingtontimes.com.