No. It's the water supply. The pig became sick and died, they purposely showed water when Patrick kicked the bucket at the end, AND, if you watched the comercials during the marathon, you would have seen the one clip where Carrol was leaning over to get a drink from the little stream out front of the prison, and Rick was screaming at here to not drink from it. Besides, if they could turn from someone's spit, Glen and Maggie would have died LONG LONG LONG ago. Lol.