Can bird flu be spread from people to birds? or only from birds to people?

Avian influenza: The ability of a strain of influenza to cross from animals to humans is always a concern. What is more significant is the ability, after crossing from birds to man whether it will then continue from man to man. Whether humans give it back to birds is not known and highly unlikely. The epidemiology of influenza is a major topic by itself and quite important in predicting human outbreaks. Keep at it.

Avian Flu: It's hard to answer your question but to the best that we know, it mutated to cross from avian reservoir to humans. The opposite has not been seen or proven.