There is no "zombie apocalypse" happening. What you're seeing is two things:
1) Connections between bizarre news stories that aren't there. This is partially because of sensationalist reporting, but also because people on the Internet are indulging in a bit of fun. See also, Summer of the Shark.
2) A major news fail. I get someone on Facebook tying a bunch of incidents together and joking about it, but why journalists lend it credence is beyond me. As far as I can tell, these are pretty serious attacks, at least some of which involve the use of a new designer drug whose long-term effects are largely unknown.
I don't know if these attacks really are happening more or if the reports are just out there in greater numbers, but I think that's worth looking into. If we do have a serious crisis on our hands, let's deal with the causes. No one should be chewing off someone else's face. If we're just gonna laugh that off, then maybe we're the zombies.