Yeah, that could be a way to do it. But still it's not very contageous unless they handle animals and don't wash their hands afterwards.

Well, I guess they must have some mutated strain because bubonic plague is easy to treat with antibiotics and it is not very contagious. At least not in Syria where Muslims wash themselves 5 times per dayday. Or maybe that is why they choose bubonic plague? It only is contagious to the non-religious.