Knox county is quarantined. Though what if the infection hasn't spread out of Knox County; or it has, but hasn't had that much of an impact due to aforementioned strict quarantine. I'd think some people would love to do tests on the munchers. Also, considering the nature of the army, I'd expect some form of chain and command being adhered to, even if those in the military are essentially left to die. (I'm sure there'd be mass hysteria about Knox County if this was found out anyways, the military, and the government as a whole would go to drastic measures to make sure the infection stayed in Knox County at the very least.