Also known as the Black Death, this is the same bacterium (Yersinia pestis) that wiped out millions of people in the 14th century. While the disease is rare in the U.S., it's not defunct. On average, we'll see seven cases per year:
You can get infected from a flea bite or contact with infected tissues or fluids from handling an animal — such as a squirrel, chipmunk, or other rodent — that is sick with or died from the disease. You can also get it from inhaling droplets in the breath of infected cats or humans.
Most of the cases tend to crop up in the rural West, especially in southern Colorado, northern New Mexico, northern Arizona, California, southern Oregon, and western Nevada — places that rodents that carry the disease call home.
Comment: Rodents probably had very little to do with the spread of the Black Death. There is a growing body of evidence that the plague has a cosmic connection:
An infection causes flu-like symptoms such as high fever, chills, nausea, weakness and swollen lymph nodes in the neck, armpit, or groin.