1) No disease, fungus, chemical, or anything else is going to get around the basic laws of physics or change human biology so significantly.
There's a reason that people die when you shoot them. It's because our bodies can't operate without consuming oxygen, and we need all of those organs in order for that process to happen. Without circulating blood, the brain will die in minutes. No virus is going to allow part of it to keep operating without the necessary chemical reactions needed to provide it with the energy to do so.
2) Even if there were a thousand zombies for every survivor, the survivors would have little trouble wiping them all out. It's basic math- if you can set aside an hour day to kill zombies, and kill even just 100 zombies an hour (easily and safely done with a spear-like weapon that extends your reach while you sit behind a defensive position), you can kill 1,000 zombies in ten days. A small group of survivors could clear an entire town's worth of zombies, put up a fence for the occasional stragglers, and not have to worry anymore.
You'd need Return of the Living Dead style zombies, which retained their intelligence and were nearly unkillable, to be an actual threat to humans.
There's a reason that people die when you shoot them. It's because our bodies can't operate without consuming oxygen, and we need all of those organs in order for that process to happen. Without circulating blood, the brain will die in minutes. No virus is going to allow part of it to keep operating without the necessary chemical reactions needed to provide it with the energy to do so.
2) Even if there were a thousand zombies for every survivor, the survivors would have little trouble wiping them all out. It's basic math- if you can set aside an hour day to kill zombies, and kill even just 100 zombies an hour (easily and safely done with a spear-like weapon that extends your reach while you sit behind a defensive position), you can kill 1,000 zombies in ten days. A small group of survivors could clear an entire town's worth of zombies, put up a fence for the occasional stragglers, and not have to worry anymore.
You'd need Return of the Living Dead style zombies, which retained their intelligence and were nearly unkillable, to be an actual threat to humans.