Fourteen people in Auckland are now being treated as having swine flu with another 31 suspected cases nationwide.
At a press conference in Wellington this morning, health officials said there were now 12 people from Rangitoto College who had tested positive for Influenza A - one more than last night. They believed all 12 had swine flu.
It also emerged this morning that two Auckland travellers, who had returned to New Zealand on US flights, were also being treated for swine flu after testing positive for Influenza A.
Officials said while World Health Organisation swine flu tests in Melbourne had only been completed on three swabs sent from the Rangitoto College party – all three had come back positive. Therefore they believed the rest of the group, plus the two Auckland travellers, also had swine flu.
"We are assuming from the results of Melbourne that everyone in that group... were positive for swine flu,” said Auckland Regional Public Health Service (ARPHS) clinical director Dr Julia Peters.
"We just have to accept as if it is [swine flu]. We can't get all the results, we just have to prioritise," she added.
All those that have tested positive for Influenza A will be tested for swine flu. Tests are still being conducted in Melbourne, but it is likely swine flu testing will shift to ESR labs in Wellington in the coming days.
Health Ministry deputy director general Dr Fran McGrath said a new case definition had also been introduced, which reduced the time someone was considered susceptible after visiting Mexico or North America from two weeks to one.
Meanwhile, Dr Peters hit back at reports the Rangitoto party was to blame for bringing swine flu into the country.
"They should not be blamed for that. We should be thanking them and their families for co-operating..."
She said some of the infected Rangitoto College pupils - who had completed 72 hours of Tamiflu treatment - would be allowed out of isolation as they were no longer infectious.
"When they are released from quarantine, [we need to] accept that they are not infectious, they are cured. We need them to go back to school without questions being asked."
There were no other probable cases outside Auckland as yet but 31 people around the country had been tested for Influenza A and were suspected of possibly having the illness. They include 10 people in Nelson, eight in Christchurch, four in Hutt Valley, two in Taranaki, five in Waikato and another five in Auckland. At least 179 people are in isolation nationwide.
Meanwhile, two women with suspected flu symptoms were detained by health officials after arriving at Auckland Airport this morning.
An Auckland Regional Public Health Service official said the two arrived on a Qantas flight from Los Angeles early this morning.
They have been taken to Middlemore Hospital and will be tested for swine flu.
Thousands of New Zealanders may have been exposed to the deadly swine flu virus because of a three-day delay in alerting health boards to potentially infected people.
The swine flu virus has killed close to 150 people in Mexico and infected dozens in the United States, Canada and Europe. Spain's health minister has confirmed a second case of swine flu, while Israel also confirmed one case.
As confirmation of the outbreak emerged, the Government faced criticism for its response to the crisis.
Officials have admitted they did not send swabs taken from the 11 pupils for testing till Monday night, missing a flight to Melbourne because of delays in packaging the samples.
The Government has now moved from trying to contain the outbreak to attempting to minimise it.
Another member of the school group tested positive for influenza A yesterday.
Rangitoto College principal David Hodge said most of the school party, which visited Mexico on a three week trip, had recovered with only one student, who already suffered from asthma, still unwell.
He said he was shocked at the test results, "even though it was a possibility''.
But Auckland Regional Public Health officials said the families of the swine flu-infected had taken the news well.
Officials did not plan to update New Zealand's health alert code from "yellow" to "red" following the positive results. The result merely confirmed that it had been "sensible for us to have been cautious", Public Health Director Mark Jacobs said.
Dr Jacobs said the general public did not need to worry as officials were working to contain the spread and those with confirmed swine flu had so far experienced mild symptoms.
"There is no indication it is any more or less contagious than any other form of influenza,'' he said.
It was most contagious a day before symptoms appeared and up to seven days after. The greatest risk was in the early days.
All but 18 of the 356 people on board flight NZ1 have now been contacted, offered Tamiflu and been asked to stay in voluntary home isolation.
Auckland doctor Jim McVeagh, who works at a private accident and medical clinic, said everyone should have been contacted immediately it became apparent passengers had symptoms of the deadly swine flu.
Dr McVeagh treated a patient on Monday from the same flight as the infected pupils. She had rung Health Line and been told to visit her doctor "one of the most spectacularly bad pieces of advice" he had heard.
"I am hoping this isn't a big deal, because we've probably already missed the boat with containment. I think the Health Ministry has been a bit tardy, a bit relaxed."
Reports of the outbreak began emerging from Mexico on Thursday. But there were no plans to screen passengers arriving from North America till the Rangitoto pupils showed symptoms.
Auckland Regional Public Health clinical leader Julia Peters defended the response time, saying health authorities could not act till they knew what they were dealing with.
"As soon as we got a provisional diagnosis we swung into action and began contacting people ..."
She said test samples were not sent to a specialist lab in Melbourne before Monday because they required special preparation and packaging.
The Health Ministry's emergency planning co-ordinator, Steve Brazier, said initially Auckland authorities were doing all the contact tracing. "However, when the size of the task was appreciated on Monday a decision was made to refer potential cases from Flight NZ1 to regional public health units around the country to follow up in their area."
The Government has upgraded it travel advisory warning to Mexico, warning of a high risk to health and advising against all non-essential travel.
Health Minister Tony Ryall dismissed criticism yesterday, saying the initial response had been rapid, thorough and appropriate for the level of risk at the time.
"This is a threat New Zealand has planned for. Many of the best people in the health service are working night and day to protect the health of New Zealanders."
The World Health Organisation has raised its pandemic alert level to phase 4, indicating significant increased risk of a pandemic a global outbreak of a serious disease.
-By ANNA CHALMERS, MICHAEL FIELD, KERRY WILLIAMSON, and RUTH HILL
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