Warts seem to come from just about anywhere. Of a pen full of claves you might get one or 20 that get them and the rest aren;t bothered. They'll go away in time on their own or you can crush a couple of them and make them bleed, that may or may not accelerate them going away.
OR, you can tear some off and feed them back to them, or you can tear them off and feed them to the neighbors cousins dog or bury them by tyhe full moon under the neighbors brother-in-laws back steps. The whole pricinicle is to make them bleed and in theory starts the reaction in the animal to fight the virus that causes them.