More than 70 people aboard the cruise ship Horizon came down with diarrhoea last week, just one year after the vessel was hit with Legionnaire's Disease.

The Associated Press reported yesterday that the US Centers for Disease Control in Atlanta was investigating the outbreak which started last Tuesday -- one day after the ship arrived in Bermuda.

A Celebrity Cruises spokesman said some of the passengers required hospital care while others were treated by the ship's doctor.

He said that although none of the passengers were seriously ill, the high number of passengers affected meant Celebrity had to report the cases to the CDC in Atlanta.

The ship is due to arrive in Bermuda today after setting sail from New York on Saturday after a thorough cleaning in New York City last week.

Government Chief Medical Officer Dr. John Cann, who has been abroad, said he was not familiar with the details but expected that the ship would have contacted his office.

Ship's agent the Wor. Henry Hayward said he had also been away and did not know details of the case.

Hospital officials could not be reached for comment.

The outbreak marks the second time passengers have been affected by health problems on board the Horizon .

During nine Bermuda-New York trips between April and July last year almost 50 passengers were thought to have been infected by Legionnaires disease, which was later traced by doctors to have originated in the ship's hot tubs.

The ship was evacuated while in Bermuda and taken 15 miles offshore in order to chlorinate her water systems.

Meyer Agencies, the ship's agents, were forced to find rooms for the more than 1,000 passengers who had to disembark.

She was later taken out of service and put into dry dock for further inspections by the CDC.

Meyer Agencies sent Celebrity a bill of more than $1 million for putting up the passengers for two nights and other expenses.

The CDC said Legionnaire's spreads in water drops and people who were even walking near the hot tubs caught the germ from breathing spray given off by the tubs.

Although the tubs had been drained by the time investigators arrived the tubs were typically kept at 100 degrees, a perfect temperature for the bacteria to thrive.