The Black Death is widely believed to have been the result of plague, caused by infection with the bacterium Yersinia pestis. Modern genetic analyses indicate that the strain of Y. pestis introduced during the Black Death is ancestral to all extant circulating Y. pestis strains known to cause disease in humans. Hence, the origin of modern plague epidemics lies in the medieval period. Other scientific evidence has indicated that the Black Death may have been in origin.
Doctor used these techniques to cure the Black Death ,bloodletting,boil balancing,surperstitious paretices, such as burning herbs and bathing in rose water and vinegar. Some people thought that this disease was a punishment from god, so they would punish themselves to say they were sorry .