CDC: Hundreds Sickened on Ruby Princess Cruise The outbreak was likely a highly contagious norovirus, which can spread rapidly in enclosed environments.

Between February 26 and March 5, at least 284 passengers aboard Princess Cruises' Ruby Princess faced an unwanted stowaway in the form of a norovirus. Such viruses often last just 48 hours, but for sufferers faced with severe diarrhea and vomiting, that's two days too many.

In an "Investigation Update on the Ruby Princess" dated March 7, the Centers for Disease Control (CDC) reported that 34 out of 1,159 crew members were also stricken with the virus. The CDC said epidemiologists and environmental health officers with the agency's "Vessel Sanitation Program" boarded the Ruby Princess when it docked in Galveston, Texas, on March 5. Still, they could not determine the source of the infection.

The CDC said that once alerted to the outbreak, the crew reportedly implemented disinfection protocols and cleaned more often—in the process, they also collected stool samples for the CDC to analyze. A Princess Cruises spokesperson told CBS crew members told sick passengers to isolate themselves in their cabins.

Narrowing down the likely cause of the illness to the norovirus wasn't a stretch. After all, cruise ships are densely packed with people, thousands of passengers and crew members living in relatively close quarters. For a virus that can spread rapidly via food, water, or surfaces, it's an ideal breeding ground. There's also the unpredictability factor: one or more passengers may already have the virus when they board and not know it—norovirus can incubate up to 48 hours before an infected person becomes symptomatic.

Princess Cruises told CBS News that the Ruby Princess had already left for a new seven-day voyage to the Caribbean and that the passengers were informed of the outbreak.