Feb 7 (Reuters) - About 90 passengers and crew on a

Royal Caribbean cruise in the Gulf of Mexico have fallen

sick with a gastrointestinal illness causing diarrhea and

vomiting, according to the U.S. Centers for Disease Control and

Prevention (CDC).

"Radiance of the Seas" departed Tampa, Florida, on Saturday

for a seven-day cruise around the western Caribbean, planning to

visit ports in Mexico, Honduras and Belize, according to

Cruisemapper.com. An outbreak of a gastrointestinal illness was

reported to the CDC's vessel sanitation program on Tuesday.

The Miami-based Royal Caribbean did not immediately return a

request for comment.

Some 89 people - about 4% of the cruise ship's 2,164

passengers - have reported being sick. Two members of the

910-person crew are also sick, the CDC said.

Royal Caribbean has increased cleaning on the ship,

collected stool specimens for testing and isolated sick people,

the CDC said. The ship is scheduled to return to Tampa on

Saturday, February 8, according to Cruisemapper.com.

The CDC has said that norovirus, a highly contagious virus

causing vomiting and diarrhea, is usually the cause of stomach

bugs on cruise ships. It is not yet known what caused the

illness on Radiance of the Seas.