An Australian piggery was quarantined after a swine flu outbreak, officials said Saturday, amid fears the virus could mutate and return to humans in a more deadly form.
An emergency team of vets and health officials shut down the farm and were tracing the movements of animals, people and equipment to determine where the infection started and contain further spread, said Nathan Rees, the premier of New South Wales state.
"There is no threat to pork products," said Rees. "All the appropriate measures are in place."
A sick farmer was believed to have infected the pigs, which began coughing at the 2,000-animal farm in Dunedoo, 360 kilometres (220 miles) west of Sydney.
No sick animals had entered the food chain and none would be slaughtered, officials said.
Experts warn of possible mutation
But experts warned the outbreak, which is Australia's first case of A(H1N1) influenza in pigs, could have other serious implications.
"The alarm bells that concern me most is that... it could mutate a little bit and come back slightly different to humans," said epidemiologist Andrew Jeremijenko.
"One of the concerns is that the virus could mutate, so that the medicines that we have don't work against it. Another concern is that it could mix with another virus like the bird flu virus... and come out as a stronger virus," Jeremijenko told public broadcaster ABC.
Latest government figures put swine flu-related deaths here at 61, with 21,668 infections and 108 people critically ill in intensive care.
Officials have warned the disease will peak this month and trials are underway for a vaccine, with mass immunisation of the population scheduled to begin in October.