I tried to download HL2's demo, but it was 3 gigabytes so I gave up.
I want the gloating rights, I'll check again here Mondayish.
Let's say for a moment, hypothetically that headcrabs were real, and they made people into zombies by attaching themselves onto their heads.
According to common sense and wikipedia, no medical procedure in the world will save anyone a headcrab has attacked. End arguement.
However, since headcrabs are adorable little fuckers and they are relatively more interesting than tedious "I GRAB TEH SHOTGUN AND BLOW DE ZSOMBE WAY DAN GET KTANA"s,
I think that zombies are actually possible. Let's take animals for example. Rather than being less intelligent than people, they resort to only a living being's most basic instinct : hunt, eat, survive.
Let's say through some electricity and and unnecessary brain surgeries, you could either make those instincts preceed all others, and or obliviate conscious thought.
Et voila, there is a generally mindless human who eats other humans and anything that moves with warm blood.
Now, the problem is, how is it spread..
Let's say that medicine had advanced far enough to make this an autoimmune disease, somewhat like a parasite that caused everything said above without the random methods. Then it would/could be possible, upon attacks from someones infected with this said autoimmune disease, an outbreak!
I have no clue what I just said. >_>