Add to that a possibility of asymptomous infection. Not only that, but assuming this would be a parasitic or viral infection, them killing the host, especially before spreading, would not be beneficial for survival, so the infection would probably become nonleathal to majority, because the surviving strands would be the ones that stay hidden the longest.

In addition, if "the efficient erradication" missed a one zombie, what guaranties are there that it was JUST one zombie? Could you trust someone who has been in contact witha a zombie, but claims not being infected? Have you been in contact with a zombie recently, mayhaps? Are you sure you haven't been?

True, but in the Zombie fiction I've come across the incubation time is extremely short. That makes it more dramatic and scary in one sense, but would make the outbreak much easier to control. In particular, if you can spread it without knowing you're infected, the world is in real trouble.

That's another thing that makes typical Zombies so easy to control. The only "people" who can spread it are dead. You can safely care for someone until the moment they die. As long as you can avoid getting bitten once they're dead, you're safe. Real diseases are so much more dangerous because doctors and nurses have to weigh the risk of getting infected against the desire to help the patient.

I'd love to see a Zombie story involving a bored nurse who follows standard safety procedures and straps a standard Hannibal Lecter style mask on any possibly terminally ill patient.