Scientists have warned of a possible pandemic threat from a new strain of bird flu virus after a case was discovered in a young woman in Taiwan.

Researchers have reported that a 20-year old woman in Taiwan has been infected with the wild avian influenza A H6N1 virus.

They say said this highlights the need to be prepared for any possible future pandemic of avian flu.

The previously healthy woman presented to hospital with flu-like symptoms and shortness of breath in May of this year.

Tests on throat-swab samples of the woman indicated an unclassified subtype of influenza A virus, according to the report.

Genome sequencing established that the virus was a novel avian-origin H6N1 virus that closely resembled chicken H6N1 viruses that have been common in Taiwan for the past 30 years.

The patient was treated with the drug Tamiflu (oseltamivir) and has since recovered, according to a report in the Lancet Respiratory Medicine journal.

It was found that the virus had a mutation that enabled it to get into human cells and cause infection. Scientists believe this means the virus concerned could be more infectious to humans.

Further tests showed that the woman worked in a delicatessen, had not been abroad for three months prior to infection, nor had she been in close proximity to poultry or wild birds. The source of her infection remains unknown.

According to scientists from the Centers for Disease Control in Taiwan and the National Institute of Public Health and the Environment in the Netherlands: "H6N1 is a low pathogenic virus commonly found in wild and domestic birds across many continents. Our findings suggest that a unique group of H6N1 viruses with the human adaption marker G228S have become endemic and predominant in poultry in Taiwan."

"As these viruses continue to evolve and accumulate changes, they increase the potential risk of human infection. Further investigations are needed to clarify the potential threat posed by this emerging virus."

One of the researchers, Dr Marion Koopmans, said viruses of the type just discovered in a human in Taiwan are quite prevalent in wild birds and have often been identified in poultry, along with other influenza viruses, resulting in generation of an ever-expanding diverse set of influenza viruses through genetic re-assortment.

"What would it take for these viruses to evolve into a pandemic strain? And an overriding question is if it is time to review our approaches to influenza surveillance at the human-animal interface?"