Interesting idea

You've got a great synopsis there and it had some interesting twists. Though it reminded me a bit of The Happening (family running to the countryside and people being inflicted with self-destructive rage), it seemed to avoid the silliness that bogged down that movie and had a central theme of fear and mistrust which I think sets it far above the idea for that movie.

I'm glad you're leaving the cause for the rage ambiguous, that really needs no explanation and it probably would hurt the impact of your story if you tried to explain it. To that regard, I was wondering if the cure in your script was an actual cure or just a way of temporarily returning people back to normal?

Also maybe you could use a real world drug, something like Lithium. It's used to treat people with bi-polar disease, but since it's used to control manic mood swings you could make the case that a higher dosage of it can bring people back down from their rages.

Interesting

It would perhaps be helpfull if we (we not the viewers) have an idea how it spreads, by contact or by beeing in the area, how long you can carry it without problems.
I think that the easyest way is to let it speard by thouching the blood of an infected person, but you can carry it for a while before showing the symptones (explains why they don't think that it speads by blood). Further on I think that it shouldn't be a virus but a new kind of germ, that is completely invisible and not to track. It would create an unsolvable mystery but at least we know what we are talking about.
This whole theory fits in properly since the neighbor was infected and the girls of the family would be infected bacause of the blood on the knife and the other spilled blood that they touched.