Days after going camping in Colorado, 7-year-old Sierra Jane Downing was diagnosed with an extremely high fever and a very dubious cause.

Thinking that their daughter was sick with a serious case of the flu, the Downings took Sierra to the hospital. It was there that they learned that she was sick with a rare 14th century disease — the bubonic plague.

“I didn’t know what was going on. I just reacted,” her father Sean Downing said. “I thought she died.”

Along with an extremely high temperature, Sierra’s heart rate was alarmingly high, her blood pressure was low, and her left lymph node was swollen.

With the rare nature of the actual disease, the attending doctors didn’t initially suspect anything serious, until a pediatric doctor Jennifer Snow came up with a wild hypothesis based on the girl’s history and symptoms. Her colleague, Dr. Wendi Drummond, a pediatric infectious disease specialist ran tests that confirmed the diagnosis.

“I credit them for thinking outside the box,” explained Dr. Tracy Butler, the director of the hospital’s pediatric unit.

With a quick diagnosis and treatment, Sierra is now recovering and is expected to be discharged within a week.

Sierra may have been infected after going near a dead squirrel at the Colorado campground. She was leaning on the ground with her sweatshirt around her torso, which was the site of the insect bites.

There have been two confirmed cases of the plague this year in the United States. The disease is transmitted via infected fleas or through contact with infected animals. Back in the Middle ages, the bubonic plague is estimated to have killed over 25 million people in Europe. Luckily, with modern antibiotics, the plague is treatable when caught early.