Wellington, April 29 NZPA - The hunt for 18 people who arrived in New Zealand on flight NZ1 early last Saturday has become more urgent, with confirmation a group on that flight has tested positive for swine flu.

Health Minister Tony Ryall last night announced the World Health Organisation laboratory in Melbourne had returned positive swine flu results from three of the 11 Rangitoto College group who had previously tested positive for influenza A.

That was enough to assume all 11 were positive.

Health authorities had accounted for all but 18 people on the flight.

They had no way of contacting them because their arrival details were insufficient, and were relying on the media to get the message out that they needed to contact authorities.

However, Director of Public Health Mark Jacobs said last night's confirmation did not change New Zealand's approach to managing the issue.

The alert level would remain at yellow, despite the test results.

"Obviously we will continue to look out for potential cases of swine flu in returning travellers," he said

"The other important thing for us to look out for is any significant amount of spread within New Zealand.

"So if we start getting cases in people who haven't been out of the country and haven't been, for instance, household members of someone who has come back from overseas, that would be a concern for us.

"It would certainly indicate we needed to escalate our responses."

The general public was at no greater risk of contracting swine flu than any other type of flu and there was no indication it was any more or less contagious than any other form of influenza, Dr Jacobs said.

It was most contagious a day before symptoms appeared and up to seven days after. The greatest risk was in the early days.

No age group was any more or less at risk, Dr Jacobs said.

He urged people to keep the illness in perspective and said anyone not directly exposed to it was unlikely to contract it.

Auckland Regional Public Health has told those affected of the results. All 11 were recovering at home, and they and their families would stay in quarantine until they had completed a 72-hour dose of Tamiflu, an anti-viral medication that slows the spread of the virus.

All were holding up well, and Rangitoto College principal David Hodge told NZPA he had huge pride in them.

"... they're such an intelligent and well-educated group, that it was well-contained," he said.

Forty-three others who had displayed flu-like symptoms since completing recent international travel would also continue to be quarantined until they had completed the Tamiflu course.

The swine flu virus has killed close to 150 people in Mexico and infected dozens in the United States, Canada and Europe.

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