The plague rarely affects humans, though the US sees about 7 cases a year. Here's why

Colorado health officials have confirmed a human case of the plague, the rare bacterial infection infamously known for killing tens of millions in 14th century Europe. Today, it's easily treated with antibiotics.

The Centers for Disease Control and Prevention estimates there are seven human cases of plague per year in the U.S., and in February, Oregon officials reported it in a person who likely got it from their sick cat.

Surprised to hear the plague is still around? Here's what to know.