Theories of The Black Death - Alternative Explanations - Counter-arguments

Counter-arguments

Historians who believe that the Black Death was indeed caused by bubonic plague have put forth several counterarguments.

The uncharacteristically rapid spread of the plague could be due to respiratory droplet transmission, and low levels of immunity in the European population at that period. Historical examples of pandemics of other diseases in populations without previous exposure, such as smallpox and tuberculosis transmitted by aerosol amongst Native Americans, show that the first instance of an epidemic spreads faster and is far more virulent than later instances among the descendants of survivors, for whom natural selection has produced characteristics that are protective against the disease.

Michael McCormick, a historian offering the idea that bubonic plague was indeed the source of the Black Death, explains how archaeological research has confirmed that the black or "ship" rat was indeed present in Roman and medieval Europe. Also, the DNA of Y. pestis has been identified in the teeth of the human victims, the same DNA which has been widely believed to have come from the infected rodents. He does not deny the point that there exists a pneumonic expression of Y. pestis transmitted by human-to-human contact, but he states that this does not spread as easily as previous historians have imagined. The rat, according to him, is the only plausible agent of transmission that could have led to such a wide and quick spread of the plague. This is because of rats' proclivity to associate with humans and the ability of their blood to withstand very large concentrations of the bacillus. When rats died, their fleas (which were infected with bacterial blood) found new hosts in the form of humans and animals. The Black Death tapered off in the eighteenth century, and according to McCormick, a rat-based theory of transmission could explain why this occurred. The plague(s) had killed a large portion of the human host population of Europe and dwindling cities meant that more people were isolated, and so geography and demography did not allow rats to have as much contact with Europeans. Greatly curtailed communication and transportation systems due to the drastic decline in human population also hindered the replenishment of devastated rat colonies.