A teenager in Oregon has been diagnosed with bubonic plague, the illness that killed tens of millions of people in the 14th century but is treatable today.

Oregon health officials said the Crook County girl is believed to have acquired the disease from a flea bite during a hunting trip near Heppner in Morrow County. The trip started on Oct. 16, she fell ill five days later, and was hospitalized three days after that.

The unnamed girl is recovering but is still in intensive care, officials said.

During the 14th century, the plague, also known as the Black Death because of the symptom of oozing, blackened sores, killed tens of millions of people in Europe, Asia and Africa. An estimated 25 percent to 60 percent of the population of Europe — some 50 million people — died and some histories put the toll as high as 200 million throughout the world over the century.

The plague is treatable with antibiotics if caught early. Symptoms of the bubonic plague, the most common form of the bacterial infection, include high fever, lethargy and swollen lymph nodes.

According to the Centers for Disease Control and Prevention, an average of seven human plague cases are reported each year in the United States. In one week last year, four cases of the plague were reported in Colorado.

Eight human cases have been diagnosed in Oregon since 1995. No deaths have been reported.

“Many people think of the plague as a disease of the past, but it’s still very much present in our environment, particularly among wildlife,” Oregon public health veterinarian Emilio DeBess said in a statement. “Fortunately, plague remains a rare disease, but people need to take appropriate precautions with wildlife and their pets to keep it that way.”

The disease is caused by a bacteria spread by fleas that infect rodents. The most frequent advice is to avoid sick or dead rodents including rabbits, squirrels and rats. Officials also warn that pets must be protected from fleas.

There is no vaccine available.