What's the Problem With the Fleas?

I can't, i can't begin to understand this guy's thought process. Why wouldn't he just let them suck the blood of the people who had the plague? Cause he is too busy killing them right? But i don't know, i don'tknow. I mean, it worked. That's the thing. It was like, well, obviously they're not going to absorb the flea, the fleas aren'g t absorb the plague by getting soaked in blood, but they're going to drink it once it's right on them. Ing. Joe bthat that, that's what makes it so evil. If sers ish was a fucking super villain, all