Melbourne, Nov 2 (IANS): A team of Australian researchers has developed a new test to distinguish between birds that have been vaccinated against the H5N1 strain of the avian influenza virus or bird flu and those which have been naturally infected with the virus.

"Outbreaks in birds are largely being controlled by vaccination and this is limiting human exposure to this virus. With this new, more sensitive, test we can identify vaccinated birds with live virus and prevent the escape of any mutant strains," said lead researcher Farhid Hemmatzadeh from the University of Adelaide in Australia.

The DIVA (differentiation of infected from vaccinated animals) test uses a viral protein called Matrix protein 2, which reacts differently with blood serum from vaccinated or infected animals.

Avian flu has caused a global concern because of its possible transmission to humans and the threat of a pandemic if it mutates to a form that can be easily passed from birds to humans and then human to human.

"These birds that have been vaccinated but still have live, naturally infected H5N1 virus in their systems are the main source of emerging strains of the virus - and these new strains may be even more dangerous to birds or humans," Hemmatzadeh concluded.

The research was published in the journal PLOS ONE.