P&O Cruises Australia confirmed that two passengers on the Pacific Dawn, which arrived in Sydney on Monday, tested positive for H1N1 swine flu.
It was Sydney's second flu scare of the week: On Saturday, a Princess Cruises' ship, the Dawn Princess, was quarantined but yielded no cases.
This time, with the swine flu confirmed, local health authorities in Sydney requested that all 2,000 passengers from the Pacific Dawn quarantine themselves at home for one week.
According to a statement from the New South Wales Department of Health, four people who disembarked the Pacific Dawn in Sydney had tested positive for swine flu. P&O reported that four passengers had Influenza A, but only two tested positive for swine flu.
The health department said that anyone who disembarked the ship with respiratory illness would be contacted by NSW Health and should remain in isolation for at least seven days and until symptoms improve.
NSW Health also requested passengers without symptoms to remain in quarantine for seven days after leaving the cruise ship.
P&O said that ship departed Sydney on its next cruise at 10:30 p.m. local time last night after getting clearance from NSW Health to embark on a 10-day cruise to Queensland.
A small number of crew who had reported flu-like symptoms also disembarked, P&O said, as an extra precaution. The ship is also treating its onboard crew with anti-viral medication, which will be available at no cost to any passengers who display flu-like symptoms, the line said.