South Eastern Sydney Local Health District's public health unit director Professor Mark Ferson told the SMH that no patients had required hospitalisation.
The outbreak was under control and patients were being treated at the ship's medical centre, he said.
"The ship has instituted maximum control measures, including increased sanitation, and further cleaning and hygiene procedures will occur prior to passengers arriving on board this afternoon.
"Incoming passengers will be advised by the ship of the outbreak and about recommended hygiene measures."
Passengers told media an announcement about the outbreak had been made over the ship's loudspeakers.
"We were told that some people hadn't reported it for about four days," a passenger told Nine News.
Unwell people had been told to stay in their rooms and the pool had been drained, Nine News reported.
Two other cruise ships suffered from an outbreak of gastro in December last year.
About 182 passengers fell ill on the Explorer of the Seas, which had also docked in Sydney.
Later in the month, P&O's Pacific Eden was nicknamed "the floating disaster" after 60 passengers were struck down with the virus.
- nzherald.co.nz
