On his VDU's blog, Dr. Ian Mackay writes: Humans unlikely to infect poultry with H7N9? Data please! Excerpt (click through for the full post and links):
The United Nations Food and Agriculture Organization (FAO) has said that poultry is not at risk of being infected by humans carrying H7N9 virus.
In fact, we have no evidence that affected people could transmit the virus to other species, including birds. The highest risk of virus introduction is uncontrolled live poultry trade between affected and unaffected areas.
But absence of evidence is not evidence of absence. We have seen studies, like this one, that use a human H7N9 virus and use it to successfully infect chickens. So the virus is capable of replicating even if it is inefficient at spreading to other chickens or even ferrets ( a human surrogate of influenza infection). But then we do know that humans get infected from exposure to something in poultry markets.