How bad is AI? Could it affect my backyard chickens?

You are referring to avian influenza? I'm no expert but from what I have read it is usually transmitted to backyard chickens when they have contact with migratory waterfowl.

As far as signs and symptoms, in wild birds the symptoms range from none at all to death, there are many strains of AI so the lack or severity of illness is largely dependent on the strain involved. Just be aware that if you have your flock tested and they test positive the state may cull all your birds.

Personally since I don't live on a lake with wild waterfowl I am not even slightly concerned about it.

 

We've had 1 confirmed case here in UT and since we are on major migratory bird flight path, our local feed stores have had these pamphlets out. http://ag.utah.gov/documents/AvianInfluenzaStepsToProtectBrochure.pdf

While I'm not overly concerned, I guess it's always good to be aware.