Nearly 200 people sick in norovirus outbreaks on Royal Caribbean, Princess Cruises ships

Nearly 200 people got sick in norovirus outbreaks on Princess Cruises and Royal Caribbean International ships.

The Centers for Disease Control and Prevention said 94 of the 2,532 guests on Sapphire Princess reported being ill during its April 5 cruise, along with 20 crew members. The round-trip cruise, which left from Los Angeles with stops in Hawaii and the South Pacific, will end on May 7, according to CruiseMapper.

On Royal Caribbean’s Radiance of the Seas, 67 of its 1,993 guests reported being ill in addition to two crew members during a cruise that ended April 22, according to the CDC. The two-week voyage sailed from Tampa, Florida to Los Angeles with stops in countries like Colombia and Panama, according to CruiseMapper.

In both outbreaks, the guests and crew members’ main symptoms were diarrhea and vomiting.

Princess, Royal Caribbean and the ships’ crews implemented heightened cleaning and disinfection measures and isolated those who were sick, among other steps, the health agency said.

"Onboard the most current sailing of Sapphire Princess, there have been a small number of cases of mild gastrointestinal illness among passengers, the cause likely is the common but contagious virus called Norovirus," a Princess spokesperson told USA TODAY in an emailed statement. "At the first sign of an increase in the numbers of passengers reporting to the medical center with gastrointestinal illness, we immediately initiated additional enhanced sanitization procedures to interrupt the person-to-person spread of this virus. Our sanitization program, developed in coordination with the CDC, includes disinfection measures, isolation of ill passengers and communication to passengers about steps they can take to stay well while onboard."

Royal Caribbean did not immediately respond to a request for comment.

The CDC has logged six outbreaks of gastrointestinal illness on cruise ships that met its threshold for public notification since the beginning of the year. Norovirus was listed as the causative agent in five, while one was unknown.

The illness is often associated with cruise ships but outbreaks occur in communities on land as well, according to Dr. Sarah E. Hochman, a hospital epidemiologist and the section chief of infectious diseases at NYU Langone Health’s Tisch Hospital.

“There's not something special or unique about cruise ships,” she said. “It's really any type of congregate setting, but it's also happening out in the community on a much smaller scale among households and household contacts. It just doesn't come to the attention of public health as much as it does for larger congregate settings.”

Hochman said the virus is “incredibly infectious” and congregate settings tend to have many shared surfaces, such as handrails in cruise ship stairwells or elevators. “And so, if you just have one person who's shedding the virus and touches the surface and then someone else touches it and then touches their mouth, that's how it can spread in those types of settings.”

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Alcohol-based hand sanitizer isn't as effective against norovirus, and Hochman emphasized that washing hands with soap and water “will do a lot to prevent the spread.”

The news comes after more than two dozen Silversea Cruises guests got sick in a gastrointestinal illness outbreak on the luxury line’s Silver Nova ship during a sailing that began in late March.

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