CHARLESTON, South Carolina (AP) — A cruise liner hit by an outbreak of intestinal illness for a third straight trip from South Carolina returned a day early last week as operator Celebrity Cruises brought in extra crew to scrub the ship down for three days.

The Celebrity Mercury arrived early in the morning and passengers began disembarking as the sun rose over Charleston.

The cruise company reported 406 of the more than 1,800 passengers got sick after the ship's March 8 departure. Thirteen of 857 crew members also got sick.

Hundreds of passengers got sick with the norovirus on two previous Mercury cruises this year from Charleston.

The norovirus can spread quickly in closed quarters with symptoms including nausea, vomiting, diarrhoea and stomach cramps.

The Centers for Disease Control and Prevention said the cause of the outbreak on the latest cruise has not yet been determined, but passengers reported symptoms including diarrhoea and vomiting.