A gastrointestinal illness has broken out this week on the Radiance of the Seas cruise ship, according to the US Centers for Disease Control and Prevention.

The CDC's Vessel Sanitation Program said it was made aware of the outbreak Tuesday, halfway through the ship's journey.

Cruise ships are required to report these outbreaks, the CDC said. The Rotterdam, a Holland America Line cruise ship, reported theirs on Feb. 7. This is the fourth outbreak reported to the agency this year.

A norovirus outbreak on a nearly two-week-long Holland America cruise ship sickened 152 passengers and more than a dozen crew members with symptoms like vomiting and diarrhea, health officials said. Just under 6% of the 2,