China Bird Flu Evolved from Migratory Birds, Researchers Say

Researchers say the deadly new bird flu virus in China evolved from migratory birds via waterfowl to poultry and into people, and have identified a new flu virus lurking in birds that could potentially infect mammals.

The new research shows that the deadly H7N9 flu virus, which emerged in China in March, and likely to have originated in migratory birds and was transferred to domestic ducks,  according to the BBC News. 

For this study, researchers from the Shantou University Medical College and the University of Hong Kong collected samples from 1,341 sources, which included chickens, ducks, geese, pigeons, partridges, quail, fecal matter and water from live poultry markets. The research team were trying to trace the root of the outbreak.

The researchers looked at the genetic makeup of the viruses from each animal and compared them. The researchers concluded that, "domestic ducks seem to act as key intermediate hosts by acquiring and maintaining diverse influenza viruses from migratory birds."

There have been 133 human cases of the bird flu and 43 deaths.

Their report said: "Domestic ducks seem to act as key intermediate hosts by acquiring and maintaining diverse influenza viruses from migratory birds.

"This probably led to outbreaks in chickens resulting in the rapid spread of the [virus] through live poultry markets which became the source of human infections."

Although none of the additional H7 strains they detected has yet been found in humans, some are able to infect other mammals such as ferrets, the researchers said, suggesting a jump to humans may be possible.

"The discovery ... reminds us that even if H7N9 does not return, there are risks lurking amongst the great diversity of avian influenza viruses," said Peter Horby, a bird flu expert at the Oxford University Clinical Research Unit in Hanoi, Vietnam, who was not involved in the research.