That required the arrival of Yersinia Pestis, the actual causative agent of the disease itself.

FORBES: In Which We Gently Correct James Taylor

Now, whatever they call it these days, Yersinia pestis I think it is, just ignored everything we tried on Mr. Nez.

FORBES: Fact and Comment

The old Pasteurella pestis, as we used to call it in those glorious primitive days when drugs worked, was duck soup for a half dozen anti-biotics.

FORBES: Fact and Comment

The Yersinia pestis bacterium that is behind the plague is found mainly in rodents, particularly rats, and in the fleas that feed on them, the U.S. National Institutes of Health website says.

CNN: London rail excavation unearths suspected 'plague pit'

The Yersinia pestis bacteria that is behind the plague is found mainly in rodents, particularly rats, and in the fleas that feed on them, the U.S. National Institutes of Health website says.

CNN: London rail excavation unearths suspected 'plague pit'