The Centre for Health Protection (CHP) of the Department of Health investigated a suspected norovirus outbreak on the cruise ship MS Westerdam, which made a brief stop at Kai Tak Cruise Terminal on Sunday.
The CHP's epidemiological investigation identified 76 individuals (38 males and 38 females, aged 24 to 92) who had successively developed acute gastroenteritis symptoms, including vomiting, diarrhea and fever, on board since Feb 15.
According to the ship's doctor, the vast majority of patients experienced mild symptoms and remained clinically stable.
"Given the current high activity levels of norovirus in some tourist destinations, particularly in neighboring regions like Japan and Korea where activity has been rising since late last year, I urge cross-border cruise passengers and operators to pay special attention to personal, food and environmental hygiene to safeguard individual health and public health," said Controller of the CHP Edwin Tsui Lok-kin.
Norovirus infection typically causes food poisoning and acute gastroenteritis with symptoms including nausea, vomiting, diarrhea, abdominal pain, low-grade fever and malaise. The symptoms are usually self-limiting and most people will get better within one to three days.
CHP staff members, including medical and nursing staff, immediately boarded the cruise ship after it arrived in Hong Kong at 4 am Sunday.
They conducted epidemiological investigations and environmental assessments, and inspected the ship’s environment and food hygiene.
The CHP also set up a temporary medical station at Kai Tak Cruise Terminal to provide health assessments for passengers, and instructed the cruise operator to conduct a thorough cleaning and disinfection of the cruise ship after passengers disembarked.
The cruise ship had approximately 2,000 passengers and 800 crew members when it arrived in Hong Kong. It operates a circular route and had called at ports including multiple cities in Japan, Busan in Korea, and Shanghai on the Chinese mainland since Feb 15.
The two passengers who fell ill first boarded the cruise ship in Japan on Feb 15 and developed symptoms on the same day. Other patients later developed symptoms and some of them vomited in public areas on board.
As of Sunday morning when the cruise ship arrived Hong Kong, only three individuals still exhibited mild symptoms and did not require hospitalization, the CHP said.
According to the preliminary testing by the cruise ship's laboratory services, the stool samples from seven patients tested positive for norovirus. The CHP's Public Health Laboratory Services Branch will conduct further testing.
"After inspecting the cruise ship, the CHP personnel briefed the affected individuals and the operator on health advice and necessary infection control measures, including thorough disinfection, proper handling of vomit, and attention to personal and environmental hygiene,” Tsui said.
He said the CHP also recommended enhancing training for the cruise ship’s frontline cleaning staff.
“After completing environmental hygiene inspections and epidemiological investigations onboard, and confirming that individuals preparing to enter Hong Kong were in good health, passengers and crew members disembarked this morning," Tsui added.
After the CHP confirmed that the cruise ship had undergone thorough cleaning and disinfection and the onboard hygiene conditions were deemed satisfactory, passengers and crew were allowed to board the cruise ship.
It was set depart Hong Kong for the Philippines on Sunday evening and the CHP said it will notify Philippine health authorities about the incident.
