What is a unique fact about the Bubonic Plague?

One unique and interesting fact about the Bubonic Plague is that it is caused by a bacterium called Yersinia pestis. This bacterium is usually transmitted by fleas that have fed on infected rodents, such as rats. When an infected flea bites a human, the bacterium can enter the person's bloodstream and cause a variety of symptoms, including fever, chills, headache, weakness, and swelling of the lymph nodes (buboes). Additionally, the bacterium can spread to the lungs, causing a severe form of pneumonia known as pneumonic plague, which can be extremely deadly.