Short answers, pulled from the story.
The bacterium that causes bubonic plague is named Yersinia pestis. This microbe was discovered in the late 19th century and acts as the invisible architect of the disease by turning a simple flea bite into a fatal journey through the human lymphatic system.
The Black Death lasted roughly six years from 1346 to 1352 and killed an estimated 50 million people. This pandemic originated in Central Asia and spread from Italy to the rest of Europe claiming one-third of the continent's population.
The Oriental rat flea transmits the plague by regurgitating a biofilm of bacteria from its blocked foregut into the human wound during a bite. This process seeds the wound with a microscopic army that multiplies beyond control and causes the infection to spread.
Untreated bubonic plague has a mortality rate that soars between 30% and 90% often claiming the victim within ten days. With immediate treatment using antibiotics like streptomycin or gentamicin the mortality rate drops to just 1% to 15%.
The countries with the greatest number of bubonic plague cases between 2010 and 2015 were the Democratic Republic of the Congo, Madagascar, and Peru. These nations continue to report over 1,000 cases annually to the World Health Organization.