A cat in Colorado has tested positive for the Bubonic Plague.

You read that right. The same bacterial infection that was called the Plague of Justinian back in the 6th century BC, killed one out of every four people living in the Mediterranean, then flared up occasionally every century or two before returning with a vengeance in 14th century Europe, where it was called the Black Death and killed a third of the population on the continent.

That plague.

The kitty ranges near a public park and likely caught the infection from a rat, local health authorities told KUSA, an NBC news affiliate.

Like many infections, it was never completely eradicated, and WHO statistics show about 100 people die annually of plague.

“While plague is a serious disease, and cases of animal-borne disease in household pets is never something we like to see, it is normal and expected for some animals to contract plague in Jefferson County each year,” said Jim Rada, director of Environmental Health Services for the county. “The good news is that modern antibiotics are effective against plague, and as long as it is treated promptly, severe complications, illness or death can be avoided.”

When we think of outdoor dangers to cats, we tend to think of abusive humans, vehicle traffic or poisons, but this is a reminder that nature can be lethal as well.