Many medieval people believed in the existence of supernatural beings. One story of how the plague spread told of a beautiful witch called the Plague or Pest Maiden. The maiden was “born” as a blue flame from the mouth of a dying patient. She carried a red scarf and flew from house to house. When she waved the scarf through an open window or door, those within fell victim. According to legend, the plague was stopped in one Austrian village when a brave man chopped off the maiden’s scarf-holding hand.
Source: Epidemic! The Black Death by Stephanie True Peters