Bubonic plague spread picked up speed over 300 years, study finds
The rate of infection during a plague outbreak in the 14th century doubled around every 43 days. This is a significant contrast from the 17th century, when the total doubled every 11 days.
By JERUSALEM POST STAFFA plague doctor and his typical apparel during the 17th Century Outbreak.(photo credit: Wikimedia Commons)
A new study documenting bubonic plague outbreaks in medieval Europe have found the disease spread approximately four times faster in the 17th century compared to the 14th century, Medicalxpress reported.The findings, published my McMaster University researchers in the academic journal Proceedings of the National Academy of Sciences, details how the initial infamous outbreak of the bubonic plague – the Black Death of 1348, which killed off an estimated one third of Europe – was surpassed in speed by later epidemics, which culminated in the Great Plague of 1665, according to Medicalxpress.According to the report, the rate of infection during a plague outbreak in the 14th century doubled around every 43 days. This is a significant contrast from the 17th century, when the total doubled every 11 days."It is an astounding difference in how fast plague epidemics grew," explained the study's lead author David Earn, a professor in the Department of Mathematics & Statistics at McMaster and investigator with the Michael G. DeGroote Institute for Infectious Disease Research, according to Medicalxpress.Earn's team included biologists, geneticists and statisticians. Together, they analyzed a number of different available data derived from three main sources: Last wills and testaments, parish registers and the London Bills of Mortality. The former source was especially crucial, as London lacked publish records of deaths prior to the year 1538, Medicalxpress reported."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," Earn explained."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."It isn't clear why this change in its spread occurred, which is hampered by how despite the Yersinia pestis pathogen being identified as the cause of the plague, its means of transmission remain unclear, according to Medicalxpress."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," said the study's co-author 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, according to Medicalxpress.What is hypothesized is that the plague did not spread primarily through human-to-human contact, but rather through other vectors such as fleas. However, a number of factors are believed to have contributed to the accelerated pace of spreading, such as population density, cooler temperatures and living conditions, Medicalxpress reported.The data compiled by Earn's team has been turned into a digitized archive, which provides a means of analyzing the spread of diseases in historic outbreaks, as well as analyzing what factors play a role. This could offer lessons in understanding pandemcis in the modern day, such as the coronavirus pandemic, Medicalxpess reported.
