The presence of swine flu in New Zealand has been confirmed, say health officials.
At a media conference on Tuesday evening in Wellington, director of Public Health Mark Jacobs said some of the Rangitoto College party who tested positive for influenza A on Sunday have also tested positive for swine flu H1N1.
Results from three of four samples were received earlier in Tuesday evening from a World Health Organisation-approved laboratory in Melbourne and all tested positive for H1N1. Testing continues on the fourth sample.
On the basis of these results, health authorities are assuming that all 11 people in the group who had tested positive for influenza A have swine flu.
The school group returned to New Zealand on Saturday from a trip to Mexico, the presumed source of the worldwide outbreak.
Staff from Auckland Regional Public Health are contacting those affected and informing them of the results. All are understood to be recovering at home.
Those affected will continue to receive the anti-viral drug Tamiflu and will remain in home isolation.
All 356 passengers on the flight into Auckland on Saturday with the Rangitoto College group had been urged to stay at home in quarantine. Officials says they have traced all but 18 passengers on the flight and they are being given Tamiflu.
Rangitoto College principal David Hodge says 20 more teachers and students are also off school because of contact with the group.
Mr Hodge says he has spoken to most of those who have been unwell and they are feeling much better.
Request to airlines
The Government has asked airlines to make sure a statement providing advice and information on swine flu is read out on all incoming flights to New Zealand.
Health Minister Tony Ryall Ryall says the measure is in response to the increasing international spread of the potentially fatal virus. In addition, the Health Ministry has requested that a travel health notice be given to all incoming passengers on arrival.
The Government has warned against non-urgent travel to Mexico.
No cause for alarm - Ryall
Mr Ryall told Parliament of the change in the Government's travel advisory on Tuesday afternoon. He told MPs there was cause for concern and caution, but not alarm.
The World Health Organisation has raised its pandemic alert level from phase three to four on a scale of six and is expected to lift it again, he says. The world body had indicated that work would begin on a vaccine, but it was six to eight months away.
Mr Ryall outlined the events that have led to its "code yellow" response, including the release of Tamiflu and the presence of doctors and nurses at international airports.
Mr Ryall said existing health measures were fully justified and that officials were ready for any escalation in the domestic or international swine flu situation.
The Government says a further 43 people with flu-like symptoms are being tested for influenza A, which may point to swine flu.
Mr Ryall says the world health body has asked countries to put their efforts into mitigating the effects of swine flu, rather than containing it.
Raising the level means the likelihood of a pandemic has increased, but is not inevitable, he says.
It does mean there is sustained human-to-human transmission.
Prime Minister John Key does not think New Zealand needs to follow the WHO and upgrade its response to the swine flu alert. Mr Key says a good plan is in place and he is confident health officials are doing everything they can.
Labour leader Phil Goff also says he is satisfied with the response from health officials, noting that stocks of Tamiflu are already in place.
The swine flu strain is a variant of influenza A. It is the same strain that causes seasonal flu outbreaks in humans, but the newly detected version contains genetic material from versions of flu that usually affect pigs and birds. It is spread mainly through coughs and sneezes.
Public health officials are still meeting all flights from Mexico and North America at Auckland international airport, but no passengers have so far had significant symptoms.
Officials say people who have travelled to Mexico or North America recently and have flu-like symptoms should phone their family doctor, but others with such symptoms have normal winter illnesses.
The Ministry of Health says people who have travelled to North and South America in the past fortnight should contact its healthline.
Flu is characterised by a sudden fever, muscle aches, sore throat and dry cough. Victims of the new strain have also suffered more vomiting and diarrhoea than is usual with flu.
The healthline number is 0800 611 116.