One passenger on the P&O Iona told Sky News “people have been dropping like flies”, with “a large number” of guests and staff experiencing symptoms.
“People [were] throwing up in restaurants, on decks, outside cabins,” the passenger said.
The P&O Iona, which can carry more than 5,000 passengers and 1,800 staff, is currently on a seven-day cruise across northern Europe, visiting Hamburg, Rotterdam and Zeebrugge. The current passenger numbers are unclear.
P&O Cruises has confirmed to Sky News some of its guests “have unfortunately reported gastrointestinal symptoms,” however, they said it is currently affecting fewer than 1% of the passengers on board.
A large number of families are understood to be on the cruise, which is taking place during the half-term break. It left Southampton on 15 February.
The captain of the ship is understood to have made a public announcement on Thursday informing passengers of the outbreak, and said that staff were doing their best to stop the spread of infection.
Some passengers who are isolating have said staff shortages have resulted in problems with having food delivered, as well as receiving new towels and bed linen.
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The passenger added: “Even the entertainment has been adversely affected with many of the scheduled acts unable to perform and replaced with a cobbled together entertainment programme to placate the guests.
“What was also incredulous was the inability to buy or get hold of any medication onboard to help with the symptoms. Not one shop or medical centre onboard could supply guests with gastrointestinal suspension medication or replacement salts/fluid sachets.”
P&O Cruises told Sky News any symptomatic guests who were unable to join shore experiences will receive a full refund.
They also said medication is “readily available through our onboard medical centre” and an emergency support number is available 24 hours a day.
“We are aware that some guests have unfortunately reported gastrointestinal symptoms recently on board Iona’s Northern Europe cruise,” P&O Cruises said in a statement.
“Gastrointestinal-related illnesses are very common in the UK and are predominantly spread by person-to-person transmission in environments such as hotels, schools and restaurants.
“P&O Cruises works with global, national and regional public health authorities on approved and proven protocols across our ships in order to protect the health and wellbeing of all on board.”