Reanimation of cadavers is not a far flung idea only worthy of science fiction.. even turning humans into "zombies".
Test trials deploying a variety of mixed biological agents in FL, CA and NY were successful in shutting down certain parts of the brain that controls typical and normal cognitive functions while retaining the most primitive behaviors..such as hunger, the need to feed but removing the ability to deduce what is edible and inedible.
The next step, is to make the affected.. vectors, to be human containers of various dangerous viral and bacterial bodies. Advances in engineering ("mutating") West Nile, H1N1, Ebola viruses to be more "mobile" and transferable rapidly within small, densely populated areas has been successful.