FIVE Australians suspected of carrying the deadly swine flu were in isolation last night and all Australia-bound flights from the Americas were under close watch.
NSW authorities said 17 possible cases of the new influenza strain had been traced and five people, including two children, had been tested.
Premier John Brumby said there were no reported cases in Victoria but the state was on high alert.
Health officials are preparing a national plan that would see nine million emergency anti-viral stocks sent to the worst-hit areas if the swine flu becomes a pandemic.
Planes bound for Australia from the Americas are required to report to the Australian Quarantine Inspection Service on the health status of passengers before landing.
As global fears grew:
DEATHS from the outbreak in Mexico rose to at least 103, with about 1600 affected.
HEALTH officials stressed the flu was not spread through food, so people shouldn't be afraid to eat pork.
ALERTS went out to all GPs and hospital emergency departments, warning them to look out for swine flu cases.
PHARMACISTS were inundated with requests for anti-influenza drugs, which are available only on prescription, and protective face masks.
VICTORIAN health officers joined a national crisis meeting in Canberra to decide how to respond to the threat.
The strain, believed to be a hybrid of human, bird and pig flu, is different to avian flu because it can be transferred from human to human.
The flu can take days to manifest and be contagious for up to two weeks.
Victorian health officials said the state had its own stocks of the two drugs that ease the symptoms of the flu.
Federal Health Minister Nicola Roxon said nearly nine million doses of Tamiflu and Relenza were on hand if the virus took hold in Australia.
But she called for calm, saying the threat of a pandemic was yet to be realised.
"The World Health Organisation has declared that this situation represents a public health emergency of international concern," she said.
"It has not, however, changed the pandemic phase to a higher level of alert."
A full-blown influenza pandemic could kill 25,000 Australians, according to Federal Government calculations.
Schools would be closed, footy games cancelled and workers urged to stay at home if it began spreading.
The Government's response plan sets out a staged response to a killer flu.
"The Australian Government's policy on the distribution of anti-viral medicines will focus on sustaining society and the economy," the plan says.
Victorian Chief Health Officer Dr John Carnie said there were enough stocks of the anti-viral drugs in Victoria to last for a significant period.
If the situation worsened and stocks ran low, he would issue a call to the Commonwealth chief health officer for national emergency stocks.
In the event of a serious pandemic hitting Australia, 10 per cent of Australians, or about 2.1 million people, could expect to get the illness over seven to 10 months.
Absenteeism could peak at 50 per cent in a massive blow to national productivity.
But Aussies bound for Mexico are unlikely to change their travel plans despite the deadly swine flu threat, travel officials said yesterday.
The Department of Foreign Affairs Trade has warned Australians against non-essential travel to the country.