The cause of plague infections is bacterial bacilli carried by fleas. ¹⁾

Fleas infected with plague on the body of rodents such as rats and mice, as these are the animals most often found in contaminated areas where basic hygiene is lacking. ²⁾

In the Middle Ages, the plague reached epidemic proportions, infecting many thousands of people, and thus leading humanity to death. ³⁾

The extraordinary popularization of the disease led to the plague being used as a biological weapon. ⁴⁾

Plague can also be contracted through the droplet route, in which case it is said to be the pulmonary variant of this dangerous disease. This type of disease attacks the lymph nodes. ⁵⁾

Plague hatches in the human body relatively quickly, from 2 to 10 days. ⁶⁾

Symptoms of plague include high fever (40°C), chills, headache, a rash of various shapes, petechiae, bloody eruptions, and septicemia. There may be bleeding from the nose, urinary tract, and digestive tract. Internal organs are damaged to a small degree. ⁷⁾

The most famous description of the plague comes from Boccaccio's Decameron. ⁸⁾

The most famous book about epidemic disease is The Plague, written by Albert Camus. ⁹⁾