Everyone is being urged to stock up on food and essential medicines to prepare for the disruption of normal life when swine flu hits New Zealand hard.

Health authorities issued this advice yesterday - and said that the P&O cruise ship Pacific Sun, which is due to dock in Auckland today, is carrying a Kiwi who had tested positive on board for influenza A.

They said the type of flu was not yet known, further tests would be done in Auckland and the woman now had no symptoms. She and more than 10 close contacts would be quarantined at home.

Swine flu has infected more than 17,000 people and killed 115 globally. So far in New Zealand, it has been confirmed in just 10 cases and has generally been a mild disease, but health authorities expect it will eventually infect more than half the population.

"It is rapidly spreading internationally, especially in Australia," said Dr Julia Peters, clinical director of the Auckland Regional Public Health Service. "In Australia, the number of cases is doubling every two days. With the amount of transtasman travel, it's almost inevitable we are going to get it in the community in New Zealand.

"When that happens, because it's more infectious than seasonal influenza. It's going to spread, and a large proportion of the community is going to get this virus. Even if it's relatively mild, people will be too sick to go to work or school."

Dr Peters said that based on modelling by the World Health Organisation, it was predicted that 60 per cent of people would become infected with the new virus, A (H1N1).

"We are promoting getting prepared, not getting panicky."

She said that with so many people sick - including workers - services or businesses such as schools, health clinics, banks and supermarkets might not be at full capacity.

It was possible the Government would invoke special regulations to prevent the spread of the virus. This would allow officials to close schools, restaurants and other facilities, and to prevent other public gatherings like weddings, funerals and movie sessions.

Parents needed to plan how they would care for their children if schools or early childhood centres were closed. Businesses needed to decide which essential parts of their operations they wanted to keep running when many staff were at home sick.

Dr Peters urged people to stock up on three to five days of long-lasting food, and to ensure they had supplies of medicines they needed personally and fever control drugs like paracetamol.

People who developed flu-like symptoms should stay at home and call a doctor for advice rather than turning up unannounced at a clinic and risking infecting others.

Ngaire Buchanan, a member of the northern regional health emergency group, said that when transmission of the virus was widespread, people would be told of their nearest community-based assessment centre.

Staff at these facilities would check patients and treat them with Tamiflu.

Four sites for these centres have been confirmed in Auckland City, five in the Waitemata health district, three in Counties Manukau, and 14 in Northland. In the Auckland region, they will mainly be at accident and medical centres.

The Ministry of Health said it would start an awareness campaign on Saturday about swine flu, advising people what preparations to make and what arriving travellers should do if they had flu-like symptoms.

* Advice from health authorities:

Stock up with 3 to 5 days' food.

Plan for your children's schools to be closed.

Firms should plan how to cope with many staff away sick.