STOP reading now if you are about to go on a cruise holiday.
Around 182 passengers on board the Explorer of the Seas docked at Sydney have caught a nasty stomach bug while on board, according to New South Wales health authorities.
Public health director with the South East Sydney Local Health District, Dr Mark Ferson, told the ABC the outbreak started a couple of days after the ship left Sydney on December 2 and spread quickly.
"It's probably a highly infectious virus called norovirus which causes diarrhoea and vomiting," he said.
The ship, operated by Royal Caribbean, carries about 4,700 passengers and crew.
Dr Ferson said the company are very professional and have instituted extra cleaning.
"These outbreaks do occur from time to time and because the outbreak is so infectious it's quite hard to control."
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