Royal Caribbean's Explorer of the Seas cruise ship is pictured in a 2007 file photo. Photo: CNN

According to Bernadette Burden, a spokeswoman with the Centers for Disease Control and Prevention, more than 600 people on the ship have become ill. Passengers and crew members reported vomiting and diarrhea.

"New reports of illness have decreased day-over-day, and many guests are again up and about. Nevertheless, the disruptions caused by the early wave of illness means that we were unable to deliver the vacation our guests were expecting," the cruise line said in a statement.

"After consultation between our medical team and representatives of the U.S. Centers for Disease Control and Prevention, we think the right thing to do is to bring our guests home early, and use the extra time to sanitize the ship even more thoroughly," the company said.

Explorer of the Seas left January 21 from Cape Liberty, New Jersey, and it has been in the Caribbean.

After returning to its home port on Wednesday, the cruise line said it would perform a "thorough 'barrier' sanitization program on the entire ship to make certain that any remaining traces of the illness are eliminated."

The cause of the illness was not immediately clear, though symptoms are consistent with norovirus, the cruise line said.

Noroviruses spread easily and are a common cause of gastroenteritis, which produces vomiting and diarrhea.

According to Burden, the CDC spokeswoman, 564 of the 3,050 passengers and 47 of 1,165 crew members reported being ill.

Joseph Angelillo was one such person. He said he thought, at first, he just had food poisoning.

"I started with upset stomach and vomiting, and that lasted all night and into the morning," he told CNN by phone on Sunday.

He said some entertainers were sick and shows had to be canceled.

"If I can get off (the ship), I will," Angelillo said.

See previous story published on January 26, 2014:

300 become ill on Royal Caribbean cruise ship

(CNN) -- More than 300 people on a Royal Caribbean cruise ship have become ill during a voyage, the Centers for Disease Control said on its website.

According to the statement, 281 of the 3,050 passengers and 22 of 1,165 crew members of Explorer of the Seas reported vomiting and diarrhea.

In a statement to CNN, Royal Caribbean International said those who fell sick have responded well to over-the-counter medication being administered on board the ship.

Janet Diaz, spokesperson for Royal Caribbean International, told CNN that the ship skipped a planned stop in Haiti on Saturday and sailed directly to San Juan, Puerto Rico, where it underwent an extensive sanitizing.

The agency said the cause of the illness was unknown.

Diaz told CNN the use of special cleaning products designed to kill norovirus will continue to be used throughout the voyage. All responses are being coordinated closely with the CDC, she said.

Noroviruses spread easily and are a common cause of gastroenteritis, which produces vomiting and diarrhea, according to the CDC.

A CDC health officer and epidemiologist will board the ship in St. Thomas, U.S. Virgin Islands, on Sunday to conduct an investigation, a health assessment and evaluate the response, the CDC release said.

Explorer of the Seas left Cape Liberty, New Jersey, on January 21 and is scheduled to make stops in St. Thomas and St. Maarten.