Most records intrigue the fascination of the Yersinia pestis with the poor public health standards. Modern historians suggest that the public health in the medieval ages held public health efforts for waste control, sanitation, and medicine such as herbal remedies that worked. All this was not know then once previously imagined.
If Yersinia is not transmitted by what was once known of medieval hygiene, then one may consider the exact cause.
Despite this, both accounts include superstition as the root of the cause as medieval physicians were unable to treat the disease. Furthermore, during this time of the Golden Age of Microbiology, Yersin also discovered the mode of transmission where the disease spread through a cycle of fleas, rodents (rats) and humans.