PD's and ground squirrels that is.
The fleas on both are primary carriers of bubonic plague.
The flea has an interesting ability. It can immediately sense a drop in body temperature of it's host. Once it senses a drop it will jump to the next warm body that comes near it. Another PD, your dog, or YOU :shock:
Friend of mine got plague about ten years ago. They think it was from stopping along the road to skin a road kill (don't remember the species but probably not a PD, he has more class than that
)