More than 70 people got sick in a norovirus outbreak on a Royal Caribbean International ship this month. The cases mark the 19th outbreak of gastrointestinal illness on cruises that met the Centers for Disease Control and Prevention’s threshold for public notification in 2025, surpassing 2024’s total.

Among the 1,874 passengers aboard the line's Serenade of the Seas ship, 71 reported being ill during a voyage that began on Sept. 19, along with one crew member, the CDC said. Their main symptoms were vomiting and diarrhea.

The ship left from San Diego for a cruise to Mexico, Costa Rica, the Panama Canal and Colombia, according to CruiseMapper. The cruise line increased cleaning and sanitation measures onboard and isolated sick guests and employees, among other steps, according to the CDC.

"The health and safety of our guests, crew, and the communities we visit are our top priority," Royal Caribbean Group, the cruise line's parent company, told USA TODAY in an emailed statement. "To maintain an environment that supports the highest levels of health and safety onboard our ships, we implement rigorous cleaning procedures, many of which far exceed public health guidelines."

Are outbreaks up on cruise ships?

The CDC has logged 19 gastrointestinal outbreaks on cruises so far this year, 14 of which were caused by norovirus. The illness caused 15 of 18 total outbreaks in 2024, and 13 out of 14 the year before.

"While the number of recent cruise ship outbreaks has been higher than in years prior to the pandemic, we do not yet know if this represents a new trend," the health agency told USA TODAY in late April. "However, CDC data show a newly dominant strain is currently associated with reported norovirus outbreaks on land. Ships typically follow the pattern of land-based outbreaks, which are higher this norovirus season."

A preliminary review also found a "possible overreliance on hand sanitizer on ships," which is not as effective against the virus as soap and water, the agency said.

There were 2,675 norovirus outbreaks reported by the 14 states that participate in the NoroSTAT network between Aug. 1, 2024, and July 31, according to the CDC’s website. Those are up from 1,478 during the same period in the prior seasonal year.

"The total number of outbreaks reported during the 2024–2025 seasonal year is above the range reported during the same period during the 2012–2020 and 2021-2024 seasonal years," the website reads.

Sarah R. Michaels, an assistant professor at Tulane University’s Celia Scott Weatherhead School of Public Health and Tropical Medicine, said while norovirus can spread quickly on cruise ships, most outbreaks aren’t happening there.

"They're often taking place within the community, and oftentimes we don't know that they're happening," she told USA TODAY. "Really when we have these areas where people … are in really close contact, things like daycare facilities, nursing homes and cruise ships, it’s more likely (to be) diagnosed, reported and brought to our attention."

In fact, cruise ships make up just 1% of all reported norovirus outbreaks.

How to protect yourself from norovirus

Michaels encouraged travelers to practice good hand hygiene.

"Hand washing is just such an important thing to do for a variety of infectious diseases, but for norovirus in particular, it's really important to wash your hands, especially after using the bathroom, but also before eating," she said.

If you start to develop symptoms – which can include vomiting, diarrhea and nausea – Michaels recommended self-isolation to help curb the spread. For travelers who haven’t left yet, that might mean postponing their cruise or staying in their cabins if they’re already onboard. Passengers should also report their symptoms to the ship’s medical staff.

The CDC also recommends disinfecting surfaces and washing laundry that may be contaminated.

"I wouldn’t necessarily not take that cruise, or not take that cruise for this reason," Michaels said. "But take precautions and report any illnesses."

Nathan Diller is a consumer travel reporter for USA TODAY based in Nashville. You can reach him at ndiller@usatoday.com.

This article originally appeared on USA TODAY: Cruise ship GI illness outbreaks surpass 2024 with new Royal Caribbean cases

Reporting by Nathan Diller, USA TODAY / USA TODAY

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