Health officers inspected a cruise ship yesterday after more than 90 holidaymakers and crew came down with gastroenteritis.
Eighty-eight passengers aged three to 83 and four crew members developed symptoms such as diarrhoea, vomiting and fever between May 21 and Tuesday.
Seventy have recovered, while the rest are in stable condition after receiving treatment on board the SuperStar Gemini. None required hospital treatment.
A statement issued by Star Cruises, the cruise operator, said the first cases were reported last Friday while the ship was in Ho Chi Minh City, Vietnam. They were treated by an on-board doctor and two nurses.
The Department of Health last night confirmed preliminary test results of eight stool samples collected from the passengers were positive for norovirus, a common cause of viral gastroenteritis.
It also warned that few more people who had been onboard may develop symptoms in the next few days as the incubation period for infection is 24 to 48 hours.
Carrying 639 passengers and 465 crew members, the ship left Singapore on May 20 for a 21-night cruise. It made stops in Ko Samui, Bangkok, Ho Chi Minh City and Danang before arriving in Hong Kong yesterday.
Health Department officers carried out an inspection of the ship and collected samples for laboratory tests.
'We inspected the ship with special attention to victims' bedrooms, toilets and public areas, restaurants and kitchens on board and disinfected these places thoroughly. We are quite satisfied with the hygiene standard of the vessel,' said Henry Kong, the department's chief port health officer.
'We have also dumped all the high-risk food such as salad, sandwiches and cheese, as these kinds of food are served as cold dishes.'
The department said the ship would be thoroughly disinfected before taking on further passengers. The crew had also been advised to observe good personal and food hygiene.
Star Cruises said extra precautions were being taken. These included the compulsory use of hand sanitisers and the constant cleaning of public areas and cabins.
Some passengers suspected seafood might be the source of the infection.
'We ate some clams with spaghetti [on Sunday] and I felt sick after eating the dish. I was sick for about two days. The food made me vomit,' said Mrs Lee, who joined the cruise with her husband.
Australian Doug Markey, 75, who boarded the ship in Hong Kong with his wife yesterday, said he was not worried about food poisoning. 'I always travel around Southeast Asia and I am not too worried about it.'
The ship left Hong Kong at 9pm and continued its voyage to Halong Bay, Vietnam.