Black Death: The Most Devastating Pandemic?

FROM THE LECTURE SERIES: The Medieval Legacy

By Carol Symes, University of Illinois Urbana-Champaign

The influenza pandemic of 1918–19 was a tragedy true to its Greek etymology: affecting ‘all people’ within a very brief span of time, causing an estimated 50 to 100 million deaths and multiplying the miseries of the Great War, which had helped to facilitate its global spread. But was this modern plague really ‘the mother of all pandemics’?

Painting showing the devastation caused by plague.
Historically, there are documented influenza pandemics dating back to the late 9th century, and all of them were zoonotic diseases—just like the Black Death. (Image: Pieter Brueghel the Elder/Public domain)

Emergence of Plague

In 2018, the medical researchers David M. Morens and Jeffery K. Taubenberger commemorated the centenary of what they had earlier called ‘the mother of all pandemics’. However, in the past decade, interdisciplinary teams of historians, archaeologists, and scientists have been able to amass and analyze evidence to show that the medieval plague known as the Black Death is more deserving of this opprobrious moniker.

For example, as Dr. Monica H. Green has documented, the Black Death was actually caused by four separate but related strains of the organism Yersinia pestis, and still constitutes the most devastating global pandemic known to us—even though, at the moment, we think it only affected half of the world.

No Single Origin

This puts into wider context the similar findings of Drs. Morens and Taubenberger, who have rejected all known hypotheses as to any single place of origin for the influenza pandemic of 1918–19. Instead, they posited that “the virus had been silently seeded around the world”, possibly well before 1918, to be triggered almost simultaneously in numerous locales. DNA since retrieved from victims who perished between the spring of 1918 and winter of 1919, from a geography spanning Alaska to England, “show little variation” and are all equally virulent.

The name Spanish flu, then, is a xenophobic misnomer; it reflects the fact that the combatant nations of the Great War, which did not end until November of 1918, actively censored news reports of its spread. Only in neutral Spain was the reportage allowed, which gave rise to the erroneous narrative that it had emerged there.

This article comes directly from content in the video series The Medieval Legacy. Watch it now, on Wondrium.

Zoonotic Diseases

Historically, there have been documented influenza pandemics dating back to the late 9th century of our era, all of them zoonotic diseases—just like the Black Death. That is, they are caused by the transfer of germs from animals to humans.

Diagram showing the spread of Zoonotic diseases.
Zoonotic diseases are caused by the transfer of germs from animals to humans. (Image: Arcady/Shutterstock)

In both cases, the rapid spread of zoonotic diseases is traceable to multiple vectors, including the globally mobile population of wild waterfowl and shorebirds—which could, of course, travel widely and rapidly even in ages when humans could not.

Not surprisingly, scientific data show a marked surge in the truly global scope of influenza just when we would expect it—in 1510, when European colonization of the Americas was devastating indigenous peoples with no immunity to foreign diseases. We then observe a steady increase from there, until further marked upticks in the mid-19th century, when steamship travel fueled growing global trade and tourism industries, resulting in the pandemic of 1889.

Mortality Rates

Indeed, Morens and Taubenberger found that, in 1918–19, mortality disproportionally affected adults in the prime of life, with those aged 20–40 dying three times more often than their older and younger contemporaries—hence the number of tragically orphaned children.

Within this group, the highest mortality rate occurred around the age of 29—that is, among those who had been born during or just after the pandemic of 1889, and who had not benefited from any of its immunological effects. The same seems to be true of those who survived the Black Death; they had developed antibodies that could alleviate the effects of the successive waves of plague that continued to impact the Afro-Eurasian landmass for centuries thereafter.

To be sure, the much smaller global population of the 13th and 14th centuries could not make this medieval plague equally deadly in absolute numbers when compared to the 50 to 100 million fatalities ascribed to the great influenza pandemic. Yet the Black Death surpassed that catastrophe in the percentage of people eradicated—at least 40 and 60 percent of the total affected population, compared to between 2 and 5 percent of the global population in 1918.

Mortality of the Black Death

Moreover, if we look back at the data provided by Taubenberger and Morens, which maps influenza epidemics from the 9th century on, we see that the mortality of the Black Death was even worse, because it was compounded by the previous population loss of the preceding few decades, which had been caused by the rapid cooling of the Earth’s climate at the end of the Medieval Warm Period and a decade-long series of famines in the Northern Hemisphere.

We need to recognize that such episodes are inevitable; they are a feature, not a bug, of any civilization. All can be linked to increased human and animal mobility and commensality, or any changes that enable more widespread travel and the exchange of commodities—as well as the sharing of pathogens among animals, insects, and humans who, living together in close quarters, are com-mensa, ‘sharing a common table’.

Common Questions about the Black Death

Q: When was there a surge in the spread of pandemics?

Scientific data show a marked surge in the truly global scope of influenza in 1510, when European colonization of the Americas was devastating indigenous peoples with no immunity to foreign diseases. There can be observed a steady increase from there, until further marked upticks in the mid-19th century, when steamship travel fueled growing global trade and tourism industries, resulting in the pandemic of 1889.

Q: How did mortality affect adults in 1918-19 pandemic?

In 1918–19, mortality disproportionally affected adults in the prime of life, with those aged 20–40 dying three times more often than their older and younger contemporaries. Within this group, the highest mortality rate occurred around the age of 29—that is, among those who had been born during or just after the pandemic of 1889, and who had not benefited from any of its immunological effects.

Q: Why was the mortality of the Black Death bad?

The mortality of the Black Death was bad because it was compounded by the previous population loss of the preceding few decades, which had been caused by the rapid cooling of the Earth’s climate at the end of the Medieval Warm Period and a decade-long series of famines in the Northern Hemisphere.

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