(Reuters) The world has yet to see a form of the deadly bird flu virus that could spread easily between people and cause a global outbreak – but that doesn’t mean it won’t happen, scientists said on Thursday.

After studying 15 years of data on bird flu viruses in the wild, researchers said some strains were already part way along the road to acquiring a handful of mutations needed to change into a form that could cause a devastating human pandemic.

“The remaining… mutations could evolve in a single human host, making a virus evolving in nature a potentially serious threat,” Derek Smith of Britain’s University of Cambridge, who led the research, told reporters.

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