How they survived bubonic plague, just barely

Since April of this year, there have been 11 cases of plague in the United States. It's a frightening disease with a horrific history: It killed tens of millions in Europe between the 14th and 17th centuries. Today, the only treatment are antibiotics, invented in the 20th century, and they have a success rate over 80%. But without intervention, the death rate is between 66% and 93%.