About 200 passengers have been confined to their cabins after the norovirus bug spread through the cruise ship while on a trip around New Zealand.
Dawn Princess arrived in Dunedin, from Akaroa, at 7.20am on Sunday and departed for Fiordland at 5.55pm the same day.
Health authorities were alerted to the outbreak when the ship was in Fiordland.
It is now on its way to Australia.
Canterbury Medical Officer of Health Dr Alistair Humphrey said Dawn Princess had its own doctor on board and the ship's crew were confident they could control the situation.
''The number of cases is declining. They're still seeing a few coming in but not as many,'' Dr Humphrey said yesterday afternoon.
''They stand at a little over 200 people altogether.''
The cruise line spokesman said most passengers were unaffected by the outbreak and it took relatively few cases for stringent sanitation levels to be implemented to contain any spread of the illness.
The containment response was timely and effective and the number of new cases declined significantly.
The proactive onboard response included disinfecting high-touch surfaces such as railings, door handles and lift buttons; isolating ill passengers in their cabins; closing all self-service food areas; and encouraging passengers to use their own cabin bathroom facilities, he said.
Although he would not confirm if any passengers visiting Dunedin had norovirus, if they did it was standard protocol for the relevant public health authorities to be notified and those passengers would remain isolated in their cabins.
The Southern District Health Board did not return calls last night. Dunedin City Council business development adviser Sophie Barker said neither the council nor Dunedin's iSite visitor centre was notified of any passengers with norovirus being in Dunedin.
''We would expect to be notified if anything like that happened.''
Norovirus was a notifiable illness so public health authorities should be informed if norovirus was onboard.
At a ''cruise action group'' meeting in Dunedin tomorrow, she planned to talk to tour operators about what to do if there was a norovirus outbreak.
''They are in contact with international visitors all the time. They always have to be very careful with hygiene.''
- Additional reporting NZME.
