Officials with the CDC boarded the Caribbean Princess early Friday and are overseeing sanitation of the vessel before it departs for its next journey on Saturday, Benson added. Crew will clean all surfaces of the ship — from elevator buttons to railings — with a special liquid disinfectant.
"To have people come on board when they are ill is, unfortunately, not a rare occurrence," Benson said. She said crew members confirmed the virus in a lab on board the ship and closely monitored everyone who reported to the infirmary, especially with gastrointestinal problems.
Jay Herring, a senior officer for Carnival Cruise Lines from 2002 to 2004, said norovirus spreads easily on a cruise ship where thousands of people travel together in a confined space.
"One time we had three consecutive cruises that had norovirus and it wasn't until we got serious about disinfecting that we got rid of it," said Herring, also the author of "The Truth About Cruise Ships."
"Every casino chip, every elevator button, every hand rail was disinfected," he added.
Herring doesn't believe having just over 3 percent of the passengers and crew ill was enough to cut short the voyage. But he doesn't recall fog ever ending a voyage when he worked for Carnival Cruises.
"I think the norovirus and the fog combined together is what ended this cruise early. I think the norovirus played a role," Herring said.
By and large, Hajewski said the cruise was fairly normal for those who didn't become sick. She said she and her traveling companion were not infected. The pools remained open, the food was good and, at first, the weather was pleasant. Unlike reports from the Royal Caribbean cruise of people vomiting in bags, buckets and even on the floor, she said she didn't see anyone get sick.
She said the crew handled the situation professionally and were strict about quarantining ill passengers.
"It's just a disappointment to miss a port," Hajewski said.
She added that "there are no guarantees that everything will go as planned no matter where you travel. Whether it's a cruise, whether it's land travel, you're always taking a risk."
Plushnick-Masti can be followed on Twitter at https://twitter.com/RamitMastiAP .
Associated Press writers Diana Heidgerd in Dallas and Mike Stobbe in Atlanta contributed to this report.