CDC Confirms Norovirus Caused Nearly 700 To Fall Ill On Royal Caribbean Cruise

01/31/2014 03:35 pm ET | Updated Jan 31, 2014

Norovirus was in fact the cause of the gastrointestinal illness that sickened nearly 700 people on a Royal Caribbean cruise, the Centers for Disease Control and Prevention reported Friday, Jan. 31.

Fifty-four crew members and 630 passengers were sickened on the ship, called the Explorer of the Seas. The CDC reported that the source of the norovirus outbreak has still not been pinpointed, and "it's quite possible a source won't be identified."

The outbreak of norovirus is one of the largest in the last 20 years, the CDC said.

The Explorer of the Seas will be sanitized, with no one allowed on board for 24 hours or more, the Associated Press reported.

Norovirus is a virus that causes stomach flu symptoms; it's especially common on cruise ships and other areas where people are kept in close quarters. It's extremely contagious, and can spread by consuming food or drink contaminated with the virus, or touching contaminated surfaces or infected people.

Just today, the Associated Press reported that a more than 170 people aboard a Princess Cruises ship were sickened with norovirus; the ship had returned early to a port in the Houston area due to fog.