New Zealand health officials are concerned by the apparent domestic transmission of swine flu in Australia.
Several Australian schools have been closed and hundreds of children's sports matches have been cancelled in the country which, by yesterday, had 12 confirmed cases but no deaths.
Several of the cases had nottravelled overseas, which suggests the disease, influenza A (H1N1), may be spreading within Australia. Internationally there were 12,022 laboratory-confirmed cases to yesterday, including 86 deaths.
New Zealand's tally remains nine, with no deaths.
The disease generally causes only mild illness, although authorities are concerned about the possibility it could mutate into a more virulent form.
Japan, which has had 321 cases, most of them domestic infections, has eased measures imposed to limit the spread of the disease. Last week more than 4800 schools and kindergartens were closed.
New Zealand's director public health, Dr Mark Jacobs, said: "The more countries getting cases and the more countries seeing local spread, the harder it is for us to delay the entry and spread around New Zealand of the virus."
He said Australian authorities were investigating two or three cases where they had found no links to overseas travel.
Dr Jacobs said that if Australia had increasing numbers of cases not linked to foreign travel, "it will be of more and more concern. If it gets to a point of lots of cases and sustained community spread, we will have to be thinking pretty hard what we can do at our borders to try and delay entry [of the virus] to New Zealand."
This did not mean restricting flights, but possibly increasing the number of health workers stationed at New Zealand airports to screen people arriving from Australia, in the way those from areas at higher risk for swine flu, like North America and Japan, were screened now.
The Ministry of Health is confident it has contained the virus so far.
"There remains no evidence of community spread of the virus in New Zealand," it said yesterday. "All of New Zealand's cases had recently returned from travel in affected areas or were close contacts of cases."
