Actually a human case of avian influenza H5N1 was first identified in China twelve years ago in 1996. Since then, Indonesia and Vietnam have been by far the worst-hit countries for human infection, although rates peaked in 2006 and have declined significantly. There's a table of confirmed cases here and useful maps elsewhere on the WHO site.
At the moment, H5N1 seems very difficult to catch if you're human. "Officials" are far more worried about an influenza virus that needs no mutation to infect humans, as seems to have happened in 1918.
BTW there a lots of pathogens that can be caught from animals, or originally thought to come from them and can now circulate independently as a human disease; eg all seasonal influenza A, measles, toxoplasma, HIV, campylobacter, hepatitis E, ebola, salmonella, West Nile... to name a fraction.
BSE is one case where we appeared to give the infectious proteins a particularly nice helping hand.