I think Glenntaj is right?
I do know that my area newspaper reports under an 'animal update' any creatures who have been captured and reported with 'rabies, west nile, and other issues' on a weekly basis. I even called them about a rabies report which occurred in my neighborhood - all were helpful...
The dead bird thing is real and true - one can shovel up [NOT touch] and bag a creature and call for pick up...or you drop off...it's tested and you get feedback.
As for 'getting' West Nile from IVIG...purty durn hard! Here's a link to the FDA...Believe me, this stuff is gathered, registered, certified, processed and pedigreed well, better than MILK! Far, far better than any manufactured narcotics for sure.
This to me, is one of the SAFEST treatments [IF properly prepared and administered there is ever!
http://www.fda.gov/cber/blood.htmed by the pharmacy and infusion specialists]

Believe me, I checked all this stuff out thoroughly before I decided to TRY it, then commit to it!
More Hugs - j