Scientists Find Medieval Plague Outbreaks Picked up Speed Over 300 Years

Related Articles

McMaster University researchers who analyzed thousands of documents covering a 300-year span of plague outbreaks in London, England, have estimated that the disease spread four times faster in the 17th century than it had in the 14th century.

The findings, published today in the Proceedings of the National Academy of Sciences, show a striking acceleration in plague transmission between the Black Death of 1348, estimated to have wiped out more than one-third of the population of Europe, and later epidemics, which culminated in the Great Plague of 1665.

Researchers found that in the 14th century, the number of people infected during an outbreak doubled approximately every 43 days. By the 17th century, the number was doubling every 11 days.

 

“It is an astounding difference in how fast plague epidemics grew,” says David Earn, a professor in the Department of Mathematics & Statistics at McMaster and investigator with the Michael G. DeGroote Institute for Infectious Disease Research, who is lead author on the study.

Earn and a team including statisticians, biologists and evolutionary geneticists estimated death rates by analyzing historical, demographic and epidemiological data from three sources: personal wills and testaments, parish registers, and the London Bills of Mortality.

It was not simply a matter of counting up the dead, since no published records of deaths are available for London prior to 1538. Instead, the researchers mined information from individual wills and testaments to establish how the plague was spreading through the population.

“At that time, people typically wrote wills because they were dying or they feared they might die imminently, so we hypothesized that the dates of wills would be a good proxy for the spread of fear, and of death itself. For the 17th century, when both wills and mortality were recorded, we compared what we can infer from each source, and we found the same growth rates,” says Earn. “No one living in London in the 14th or 17th century could have imagined how these records might be used hundreds of years later to understand the spread of disease.”

While previous genetic studies have identified Yersinia pestis as the pathogen that causes plague, little is known about how the disease was transmitted.

“From genetic evidence, we have good reason to believe that the strains of bacterium responsible for plague changed very little over this time period, so this is a fascinating result,” says Hendrik Poinar, a professor in the Department of Anthropology at McMaster, who is also affiliated with the Michael G. DeGroote Institute for Infectious Disease Research, and is a co-author on the study.

The estimated speed of these epidemics, along with other information about the biology of plague, suggest that during these centuries the plague bacterium did not spread primarily through human-to-human contact, known as pneumonic transmission. Growth rates for both the early and late epidemics are more consistent with bubonic plague, which is transmitted by the bites of infected fleas.

Researchers believe that population density, living conditions and cooler temperatures could potentially explain the acceleration, and that the transmission patterns of historical plague epidemics offer lessons for understanding COVID-19 and other modern pandemics.

This new digitized archive developed by Earn’s group provides a way to analyze epidemiological patterns from the past and has the potential to lead to new discoveries about how infectious diseases, and the factors that drive their spread, have changed through time.

MCMASTER UNIVERSITY

Header Image Credit : Walter George Bell – Wellcome Collection Gallery – CC BY 4.0

Download the HeritageDaily mobile application on iOS and Android

More on this topic

LATEST NEWS

Archaeologists Excavate 1,600-Year-Old Burial Containing Ornate Treasures

Archaeologists excavating a burial ground have discovered a grave containing ornate grave goods from the 5th century AD, a period of instability during the collapse of the Western Roman Empire.

Archaeologists Discover Ancient Settlements Associated With “Polish Pyramids”

Archaeologists conducting a detailed study of the area near the Kujawy megalithic tombs, dubbed the “Polish Pyramids”, have identified the associated settlements of the tomb builders.

Rocky Planet Discovered in Virgo Constellation Could Change Search For Life in Universe

A newly discovered planet could be our best chance yet of studying rocky planet atmospheres outside the solar system, a new international study involving UNSW Sydney shows.

Sungbo’s Eredo – The “Queen of Sheba’s Embankment”

Sungbo’s Eredo is one of the largest man-made monuments in Africa, consisting of a giant system of ditches and embankments that surrounds the entire ljebu Kingdom in the rain forests of south-western Nigeria.

Woolly Mammoths May Have Shared the Landscape With First Humans in New England

Woolly mammoths may have walked the landscape at the same time as the earliest humans in what is now New England, according to a Dartmouth study published in Boreas.

Prehistoric killing machine exposed

Judging by its massive, bone-crushing teeth, gigantic skull and powerful jaw, there is no doubt that the Anteosaurus, a premammalian reptile that roamed the African continent 265 to 260 million years ago - during a period known as the middle Permian - was a ferocious carnivore.

Noushabad – The Hidden Underground City

Noushabed, also called Oeei or Ouyim is an ancient subterranean city, built beneath the small town of Nushabad in present-day Iran.

10 British Iron Age Hill Forts

A hill fort is a type of earthworks used as a fortified refuge or defended settlement, located to exploit a rise in elevation for defensive advantage.

Popular stories

Noushabad – The Hidden Underground City

Noushabed, also called Oeei or Ouyim is an ancient subterranean city, built beneath the small town of Nushabad in present-day Iran.

Ani – The Abandoned Medieval City

Ani is a ruined medieval city, and the former capital of the Bagratid Armenian kingdom, located in the Eastern Anatolia region of the Kars province in present-day Turkey.

Interactive Map of Earth’s Asteroid and Meteor Impact Craters

Across the history of our planet, around 190 terrestrial impact craters have been identified that still survive the Earth’s geological processes, with the most recent event occurring in 1947 at the Sikhote-Alin Mountains of south-eastern Russia.

The Sunken Town of Pavlopetri

Pavlopetri, also called Paulopetri, is a submerged ancient town, located between the islet of Pavlopetri and the Pounta coast of Laconia, on the Peloponnese peninsula in southern Greece.