My only reply to the "possibility" of the "rage virus" is more on the logical angle.
While I firmly believe that it's chemically possible to turn human beings into rage-filled monsters (not sure about the 30-second results thing), I can't help but wonder - if it's RAGE... pure rage... then why would the infected only attack those who aren't infected? Wouldn't they tear each other apart - as rabid animals do? If you put two rabid dogs into a pen, they will attack each other - not look for a way out to attack other dogs. Logically speaking, rage would result in "any port in a storm" in terms of an outlet.
Sure - this theory kills a good movie plot, but it's worth mentioning, even if it's just to get someone to pull the covers from over their head.