And it still does. Ground squirrels, prairie dogs, and the enviro-weenies' favorite - the black footed ferret - all are flea bags. A veritable plague incubator, long recognized and consequently nearly eradicated. Also one of the reasons you don't hunt rabbits until after a good hard frost. Every few years a case of plague shows up NW Colorado; fortunately some old sawbones recognizes the symptoms in time.
Horrifying how all of the old scourges are returning! And that in no small part due to the environazis!!