World History 1 256 - 16.3.1 The Origins and Spread of the Bubonic Plague

The bubonic plague, the most common variant of the disease caused by the bacterium Yersinia pestis, raises egg-shaped swellings known as buboes near an afflicted person’s lymph nodes in the groin, underarm, and upper neck areas. Other symptoms include fever, nausea, vomiting, aching joints, and general malaise. For the vast majority in the Middle Ages, death generally occurred within three days. The bubonic plague pandemic, which had far-reaching economic, political, social, and cultural effects throughout Afro-Eurasia, came to be known as the Black Death. This name, inspired by the blackened tissue the disease caused on the body, also came to express the fear and awe brought by a disease with a mortality rate ranging from 30 to 80 percent. That is significantly higher than the deadliest smallpox, influenza, and polio pandemics of the modern era. Although in its bubonic form the plague could not be spread from human to human, the rat flea became a major plague vector, an organism that spreads plague from one organism to another.

The black rat was one of the most capable animal hosts for the plague-carrying fleas. It was highly susceptible to the disease itself and an especially inconspicuous stowaway on trade caravans and merchant ships. Cases of bubonic plague proliferated as rats spread through the international shipping and trades routes of the Silk Roads and the Mediterranean Sea, where they colonized crowded dwellings in towns and cities. The spread of the plague only increased owing to the increased movement of people. First it was the Mongol armies, traveling over enormous distances and unintentionally bringing small mammalian stowaways among their foodstuffs. Then, owing to the Mongols’ protection of merchants and others traveling great distances during the Pax Mongolica, the disease spread further and in new directions. Finally, those forced to leave their homes for survival amid famine and environmental change created yet another pathway for the disease to spread.

Plague-bearing fleas generally preferred to feed on small rodents such as rats and marmots, but when their rodent hosts succumbed to the plague, they secured their next meal from the nearest human. Two even deadlier variants of the disease eventually emerged during the fourteenth century: pneumonic and septicemic. The pneumonic form directly infected the lungs and was spread from person to person by coughing, with a mortality rate of 95 to 100 percent. The septicemic variant, which resulted from plague bacteria circulating directly into the bloodstream, was invariably fatal and, according to contemporary observers, seemed to kill within hours of the first onset of symptoms. While historians had surmised for many decades that the plague had spread in primarily one form (bubonic) and in one direction (east to west), new evidence increasingly suggests there was a far greater diversity of spread.

Although in many regions where it struck the plague was eventually understood to be contagious, at first the means of transmission were not recognized. Some saw the epidemic as a divine punishment from God, and others speculated that it was caused by a rare conjunction of planets creating noxious atmospheric conditions on Earth. Others blamed foreign travelers, minority religious communities, or vagrants. The desperation incited by the plague’s relentless assault often led to scapegoating of marginalized populations, particularly in Europe.

Dueling Voices

The Origins of the Black Death

In the following excerpts are two different historical interpretations of the origins of the Black Death. In the first, medievalist Philip Ziegler discusses the central Asian origins of the fourteenth-century bubonic plague pandemic, arguing that abnormally high death rates near Lake Issyk-Kul point to the pandemic’s beginnings. In the second selection, new research by medical historian Monica H. Green strongly suggests the disease first developed in the thirteenth century and was largely misunderstood amid the chaos of the Mongol conquests. Green argues that the plague outbreak of the mid-fourteenth century was actually one of four “explosive proliferations of Yersinia pestis into new environments” and that its origins go beyond a simplistic narrative of rats moving westward. As you read, consider what factors might have led each historian to take a particular point of view.

Though it is impossible to be categorical about the origins of the medieval pandemic, investigations near Issyk-Kul, a lake in Central Asia, show that there was an abnormally high death rate in 1338 and 1339. Memorial stones attribute the deaths to plague. Since this area is in the heart of one of the zones in which bubonic plague lies endemic, it is likely that this was the cradle of the Black Death. From there it spread eastward into China, south to India, and west to the Crimea some eight years later.

—Philip Ziegler, The Black Death

The combined approaches of evolutionary genetics—working from modern isolates of Yersinia pestis and the retrieved genetic fragments of the bacterium reclaimed from its premodern victims—have given new parameters to the history of plague. Currently, the biological archive, which has now yielded over three dozen complete Yersinia pestis genomes in evidence of Europe’s late medieval and early modern experience of plague . . . supports the idea that one specific strain of Yersinia pestis . . . entered the Black Sea and the Mediterranean, and from there into Europe, in 1347–1348. . . . The climate crises and grain shortages of the early fourteenth century may well explain the intensity of that outbreak. . . . But the (west Eurasian) Black Death, as traditionally defined, was preceded by the terrors experienced at the sieges in Song China and western Asia [by the Mongols] in the thirteenth century. . . . The historian, working with documentary sources, will need to track the humans who are now implicated in plague’s spread. In so doing, historians would do well to adopt epidemiologists’ neutral stance toward the task of tracking infectious disease: this is not about assigning ‘blame.’ It is about documenting humans doing what humans do.

—Monica H. Green, “The Four Black Deaths”

  • How do Ziegler and Green’s arguments about the origins of the plague differ?
  • Upon what sources is Green relying for her innovative conclusions?

Many historians have focused almost exclusively on the Black Death’s impact on Europe, assuming that other regions were only minimally affected. The Americas and Australia were, indeed, entirely spared due to their geographic isolation. Other areas such as the Indian subcontinent experienced relatively mild outbreaks. However, we now know that the disease’s spread affected much of Asia, the Middle East, Europe, North Africa, and possibly some regions of sub-Saharan Africa in what are now Ghana, Nigeria, Burkina Faso, and Ethiopia. And new scientific techniques such as genetic testing are strongly suggesting that the plague developed far earlier than modern historians had believed. In its most well-documented form, it ultimately spread along international sea and land trade routes in the 1340s and by 1409 had reached port cities of the Indian Ocean trade network in East Africa (Figure 16.13). Wherever it went, the Black Death left a trail of demographic destruction and long-term damage to social and economic networks, compounded by the combined effects of drastic climate changes, rebellions, and crop failures that preceded it in many parts of Afro-Eurasia in the early 1300s.

A map is shown. Water is highlighted in white and land is shown in gray. The Atlantic Ocean is located in the southwest, the Indian Ocean in the south, and the Pacific Ocean in the east. Europe is labelled in the west, North Africa in the southwest, Asia in the north, and the Middle East is labelled in the middle. Red dashed lines indicating “Trade routes” crisscross Europe, southern Asia and the Middle East from the Pacific Ocean to the western coast of Europe. In Africa they hug the east and northeast coasts. Black arrows are shown indicating “Spread of bubonic plague (Black Death).” Two arrows begin in eastern Asia and one heads northwest while the other one heads west, splitting into two – one heads west to Europe and the other heads toward the Middle East and splits into two, one north and one continuing west. The arrow heading to the west continues along the coast and heads south along the northeastern coast of Africa. An arrow begins northeast of the Indian Ocean in South Asia and heads northeast. Two arrows begin in eastern Europe and one heads north while the other heads southwest and then breaks off into three arrows heading west and into North Africa. One arrow begins in southern Europe and breaks into two, one heading north and the other west.
Figure 16.13 This map compares trade routes with the spread of the Black Death across Asia, the Middle East, North Africa, and Europe. (credit: modification of work “TNM Download (v2.0)” by National Land Cover Database (NLCD)/United States Geological Survey (USGS)/U.S. Department of the Interior, Public Domain)

The content of this course has been taken from the free World History, Volume 1: to 1500 textbook by Openstax