For Americans planning cruise ship vacations this spring or summer, there could be reason to worry about more than rough seas, experts say.

Recent government cuts included top staff at the Vessel Sanitation Program, which is run by the Centers for Disease Control and Prevention and conducts inspections and investigates illnesses.

The reductions come amid a surge in cruise ship outbreaks fueled by a new strain of norovirus. So far this year, there have been 16 illness outbreaks reported on cruise ships in the CDC’s jurisdiction, mostly from norovirus, compared with 18 outbreaks in all of 2024 and 14 in 2023, VSP reports show.

“Certainly it’s something that would be on my mind if was getting ready to get on that cruise ship,” said Donald Schaffner, a food science expert at Rutgers University.

Here’s what travelers need to know about staying safe on board.

What happened to the CDC’s Vessel Sanitation Program?

U.S. Health Secretary Robert F. Kennedy Jr. launched a broad restructuring of the nation’s health agencies in April. The move eliminated the CDC’s Division of Environmental Health Science and Practice, which housed the cruise ship vessel program.

A CDC spokesperson said in a statement that the VSP work “has not stopped.”

How often do cruise passengers get sick?

About 18 million people board cruises in North America each year, part of nearly 32 million passengers worldwide, according to the Cruise Lines International Association. Cruise industry officials say the chance of contracting a gastrointestinal illness is far greater on land than on a ship.

Norovirus is the most common ailment tracked on ships, though other outbreaks do occur.

Of the 19 million to 21 million norovirus illnesses that occur each year in the U.S., less than 1% are tied to cruises, said Lee-Ann Jaykus, a North Carolina State University virologist who has studied norovirus.

But even that fraction of cases can mean misery for hundreds of people on ships who come down with symptoms that include sudden onset of vomiting, diarrhea and stomach pain that can last three days, according to the CDC.

Norovirus is highly contagious, often spread by food or on surfaces, particularly in crowded conditions. It can be dangerous for people with underlying health conditions, young children and those age 65 and older.

What about this new strain of norovirus?

There are many different types of norovirus, but typically one dominant strain causes illness outbreaks, Jaykus said.

This year, a new epidemic strain has emerged, called GII.17. This version has circulated at low levels for years, but it was behind a surge in U.S. norovirus outbreaks this winter.

Between Aug. 1 and April 9, more than 2,400 suspected or confirmed norovirus outbreaks were reported to a CDC monitoring system, roughly double for the same period a year earlier. The GII.17 strain has been responsible for nearly 80% of them, the CDC reported.

I booked a cruise. How can I keep from getting sick?

If people get sick on a cruise, they’re required to report the illness and isolate themselves, but many fail to do so, Schaffner said.

Passengers should be alert for signs of illness, even in others. Vomit, for instance, can spread norovirus particles into the air, he added. “If you’re in a situation where you see someone vomit, immediately walk away from them, ideally into the wind,” he said.

Wash hands often, especially after using the bathroom or before eating and drinking. Using soap and water is best; scrub for at least 20 seconds. Hand sanitizer alone won’t work well against norovirus, the CDC notes.