Colorado authorities are investigating the death of a child linked to the plague.
The 10-year-old’s identity has not been released, but officials say the death was caused from the bacterial disease.
The state’s Department of Public Health and Environment says the death comes as confirmed cases of the plague were confirmed in animals and fleas in at least six counties.
The Centers for Disease Control and Prevention says humans can get the plague if they are bitten by rodents or animals who are infected.
Tens of millions of people in Europe died from the plague during the Middle Ages, but the CDC says now it can be treated with antibiotics if caught during the early stages.