Maybe we are being hinted...
It seems to me that Palahniuk gives us hints in his writing ie: "I know this because Tyler knows this." and then i read above in the chuck palahniuk.net
"Rant takes the form of a (fictional) oral history of Buster "Rant" Casey, in which an assortment of friends, enemies, admirers, detractors, and relations have their say on this evil character, who may or may not be the most efficient serial killer of our time"
Well i just thought, you know how like serial killers who go out of there ways not to get caught and end up fooling everyone in the process? Like they can manipulate a strategically plan when they kill. Well what if Rant really is a serial killer purposely trying to kill/infect people? I don't know just thought, after all we never real hear Rants voice. I guess we got two more books till we find out. Can't wait.
(I don't know about your opinions, but while reading the book I felt that Rant was indeed trying to infect people, but not as a means to kill people. I don't know, thats just what I got from it)