The Black Death was a pandemic of primarily bubonic plague that spread via trade links from modern-day southern Russia across Europe, the Middle East, and North Africa from approximately 1346 to 1353. Ole J. Benedictow argues that this pandemic killed around 60% of Europe’s population and was spread by black rats infested with fleas who served as vectors of transmission to humans. This outbreak devastated both densely populated cities and rural villages. Mortality rates were highest in the countryside due to a smaller number of human hosts for the rat fleas. Plague was not a new disease, but this episode was the most ruinous outbreak of plague in human history. Although plague returned to Europe in later years, outbreaks were smaller and more localized than in the 14th century. This pandemic was given the name “Black Death” several centuries later, not in reference to the dark hemorrhages that occurred on some victims’ skin, but in reference to the scope of the pandemic’s destruction.

Epidemiology is a field of medical study that examines the occurrence and spread of disease and the instances of other types of health outcomes, such as injuries and non-infectious diseases. Epidemiologists investigate the pattern by which illness may spread through communities and explain the associated outcomes.