about the zombie prepardness, what your forgetting about the human brain is thats it so absurdly complex that we cant even fully use it. all it would take was for a parastie to evolve to learn to use the "empty" spaces in our brains and work outword.
Also, your underestimating human stupidity/kindness. A person collapses, and they either take him to the hospital or someone trys to give him CPR. During CPR, the zombie revives and bites the person. People think its strange but not zombification, as he was given CPR. the zombie starts shambling towards the crowd and people would assume hes going to seek medical attention. by the time hes bitting several people, someone will have hit him and called the police. the people bitten go home. its the ultimate disease scenario. One person bites two people, they each bite two more, and so on and so on, eventually we have a worldwide pandemic.
At this point people would think, hey its over there, and we're over here, theres water in between us. For starters the gestation period could allow someone on board a plane, which would then release the zombie in that part of the world.
If facing Infection type zombies, baseball bats an knifes are useless BTW. Blood transmits it, and so you'd get Infected.