As per Wikipedia, the only trueth in existance (sarcasm)
"After a bidding war with Leonardo Di Caprio production company Appian Way, Brad Pitt's Plan B Entertainment secured the screen rights to the novel in 2007.[28] The screenplay was written by Babylon 5 and Rising Stars creator J. Michael Straczynski, who identified the challenge in adapting the work as "creating a main character out of a book that reads as a UN Report on the zombie wars"."