You can lay it on them for bringing old controlled diseases back in.
This one has been there as long as anyone can remember and longer. No one has brought it back; it shows up after a wet cycle that causes population explosions of rodents, rabbits, and the like. My dad said it was the fleas, but not sure that is what the experts say now. I grew up in that area of Northern AZ where it shows so much red, but do not live there now.
There are things like TB and whooping cough that are being brought back in, but the plague has been there.