This is a tricky one because so much is still unknown about the bird flu. Plus, this essay can be written from many different perspectives: the health perspective, the political perspective (i.e. what will governments do when it hits), the environmental perspective, the cultural perspective, and so forth.
In addition, the "world point of view" is something even a whole book couldn't address.
Therefore, my first piece of advice would be to narrow the topic based upon the class for which this essay will be written as well as what your professor wants you to include. Once the topic has been narrowed, it should be relatively easy to write an outline and then research the different aspects contained therein.