The Centers for Disease Control has issued a no-sail recommendation for at least four full days for the Celebrity Mercury cruise ship to investigate recurring outbreaks of gastrointestinal illness, a CDC spokesman said Monday.

CDC spokesman Ricardo Beato said, “The CDC and the cruise line corporate staff have not yet determined why the controls that they were following have not been effective”. Beato said that a notification of the no-sail recommendation has been sent to Celebrity Cruises.

They will be required to be in port for a period of 4 days as a part of the recommendation in order for the cleaning procedures to be reviewed as well as to determine the source of the outbreak of the disease by inspecting the staff.

Daniel Hanrahan, President and Chief Executive Officer of Celebrity Cruises, issued an apology to the guests, saying, “I have made this decision to end the current sailing early and delay the next sailing because we want to maintain our high health standards on board our ships, while providing our guests with the best cruise experience possible”.

He also shared that the extra time that is being taken in order to sanitize the ship will help in prevention of any more travelers from becoming ill.